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Municipal Water and Waste Management
Membrane Technology for Waste Water Treatment
Institut für Siedlungswasserwirtschaft der RWTH Aachen
Municipal Water and Waste Management
Membrane Technology for Waste Water Treatment
Edited by:
Univ.-Prof. Dr.-Ing. Johannes Pinnekamp
Institute of Environmental Engineering
of the RWTH Aachen University
Dr. rer. nat. Harald Friedrich
Head of Department
Waste Management, Soil Conservation,
Water Management
Ministry for Environment and Nature Conser-
vation, Agriculture and Consumer Protection
of the federal state North Rhine-Westphalia
Edited by:
Univ.-Prof. Dr.-Ing. Johannes Pinnekamp
Institute of Environmental Engineering
of the RWTH Aachen University
Dr. rer. nat. Harald Friedrich
Head of Department
Waste Management, Soil Conservation,
Water Management
Ministry for Environment and Nature Conser-
vation, Agriculture and Consumer Protection
of the federal state North Rhine-Westphalia
Membrane Technology for Waste Water Treatment
Institut für Siedlungswasserwirtschaft der RWTH Aachen
Municipal Water and Waste Management
Volume 2
Preface
4
Preface
Membrane technology for the treatment of water and
waste water shows impressively how innovative, future-
orientated, and economically meaningful environmental
protection technology can be. In the past 100 years of
modern water and waste water treatment for households
and enterprises, no other new technology has been intro-
duced offering so many positive effects like the membrane
technology.
Numerous different problems in water treatment can be
solved, simultaneously resulting in significantly better
cleaning of the waste water.
Membrane technology allows the internal recovery and
reprocessing of solid and dissolved substances.
Due to the wide range of available membranes and
modules, technically suitable systems for nearly every
type of problem in water treatment can be found.
A large number of scientific institutions, industrial enter-
prises, water suppliers and waste water boards have parti-
cipated in the development and application of membrane
technology. The Federal Government as well as the
governments of the federal states support this technical
development.
In Germany, membrane technology today represents a
proven alternative to classical processes of municipal and
industrial waste water treatment. This pays off in terms
of ecology and economy because the usage of membrane
technology denotes fewer costs for water supply and
waste water disposal as well as industrial production, and
also results in significantly less environmental stress.
In municipal waste water treatment, certain types of
membrane installations – the biomembrane filtration
plants (membrane bioreactor process) – haven’t been
used often so far, both for historical and economical
reasons. But the application of membrane processes in
municipal waste water treatment may be proven to be
cost-effective, in particular if the following conditions
occur:
• the space for the new construction or the expansion
for waste water treatment plants is limited,
• the possibilities for subsequent recycling of the treated
waste water are to be used,
• advanced or additional standards for the effluent
quality of the waste water are required,
• toxic substances have to be removed,
• hygienically excellent waste water quality is demanded.
In Germany, the biomembrane filtration process has
become competitive already today in the field of domestic
and small waste water treatment plants as well as in ship
waste water treatment plants, and increasingly in muni-
cipal waste water treatment.
Membrane technology can be applied in diverse fields of
industry, which is proven by a large number of references.
In industrial waste water treatment, membrane technology
is used for production-integrated pollution control.
Preface
5
With the help of membrane technology, water – the sol-
vent most frequently used in industry – can be cleaned
to such an extent that it may be reused. The substances
filtered from the water may also be reused again for
industrial processes. Although it’s impossible to realize a
completely closed water circuit by membrane technology,
the waste water quantity may be significantly reduced by
multiplied usage of the water. Thus the enterprises save
costs.
This publication presents the membrane technology and
its application in municipal and industrial waste water
treatment in Germany according to the state of the art
and science. Examples of installations realized in an in-
dustrial scale in municipalities and industrial enterprises
demonstrate the range of application and the efficiency
of membrane installations – including planning, con-
struction and operation as well as the related costs. Thus
planners, municipalities responsible for waste water
disposal and licensing authorities are provided with a
fundamental basis for the decision whether membrane
technology might be a solution for their specific problem.
Eckhard Uhlenberg
Minister for Environment and
Nature Conservation, Agriculture
and Consumer Protection of the
federal state North Rhine-Westphalia
Sigmar Gabriel
Federal Minister for the Environment,
Nature Conservation and Nuclear
Safety
Prof. Dr. Andreas Troge
President of the Federal
Environmental Agency
imprint
6
This scientific elaboration was supported by
the Ministry for Environment and Nature Conservation,
Agriculture and Consumer Protection
of the federal state North Rhine-Westphalia.
Responsible
Dr. rer. nat. Harald Friedrich
Head of Department
Waste Management, Soil Conservation, Water Management
Dr.-Ing. Viktor Mertsch
Waste Water Disposal and Waste Water Technology
Ministry for Environment and Nature Conservation,
Agriculture and Consumer Protection
of the federal state North Rhine-Westphalia
Revising the contents of this 2nd updated edition
FiW at the RWTH Aachen University
M. Lange, Dr.- Ing. F.-W. Bolle, Dr.-Ing. S. Schilling,
S. Baumgarten (ISA, RWTH Aachen)
Revising the contents of the 1st edition 2003:
FiW and ISA, RWTH Aachen
M. Lange (chairperson), S. Baumgarten, F.-W. Bolle,
Dr.-Ing. T. Buer, J. Schunicht, Dr.-Ing. K. Voßenkaul
Team accompanying the 1st edition 2003:
Dr. V. Mertsch, I. Dierschke, K. Drensla, A. Kaste,
RBD A. Schmidt, Prof. Dr. W. Schmidt, S. Tenkamp,
Dr.-Ing. J. R. Tschesche, C. Wiedenhöft, T. Wozniak,
Dr. K. Zimmermann
Assessment of the 1st edition 2003:
Prof. Dr.-Ing. P. Cornel, Dr.-Ing. W. Firk,
Dr.-Ing. J. Oles, Dr.-Ing. T. A. Peters, U. Voss
Translation:
F. Pohl
German edition
A German edition titled
“Siedlungswasser- und Siedlungsabfallwirtschaft
Nordrhein-Westfalen: Membrantechnik
für die Abwasserreinigung”
is available with the following ISBN:
ISBN 3-939377-00-7
ISBN 978-3-939377-00-9
The translation was supported by:
Umweltbundesamt
Postfach 330022
D-14191 Berlin
FiW Verlag
Mies-van-der-Rohe-Straße 17
D-52074 Aachen
Phone: +49 (0) 241- 80 2 68 25
Fax: +49 (0) 241- 87 09 24
E-Mail: [email protected]
ISBN 3-939377-01-5
ISBN 978-3-939377-01-6
Layout
ID-Kommunikation
S 1, 1
D-68161 Mannheim
Phone: +49 (0) 6 21-10 29 24
Fax: +49 (0) 6 21-10 29 91
E-Mail: [email protected]
Cover photo
Erftverband
Greiserdruck GmbH & Co. KG
Karlsruher Straße 22
D-76437 Rastatt
Phone: +49 (0) 72 22 -105-129
Fax: +49 (0) 72 22 -105-137
www.greiserdruck.de
1
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List of contents
1 Basics of Membrane Technology 27
1.1 Basics of Material Separation by means of Membrane Technology 28
1.2 Membrane Processes in Waste Water Purification 29
1.2.1 Micro- and Ultrafiltration 32
1.2.2 Nanofiltration 33
1.2.3 Reverse Osmosis 34
1.3 Membrane Materials, Structure and Classification 35
1.3.1 Origin and Materials 35
1.3.2 Morphology, Structure and Manufacturing 36
1.4 Membrane Forms and Modules 38
1.5 Arrangement of Modules 46
1.6 Operating Modes 48
1.7 Formation of Covering Layers 50
1.8 Measures for Maintenance of the Filtration Capacity 52
1.9 Other Aspects Concerning the Use of Membrane Technology in Waste Water Treatment 55
2 Membrane Technology in Municipal Waste Water Treatment 61
2.1 The Membrane Bioreactor Process 66
2.1.1 Description of the Process and Fields of Application 66
2.1.2 Membrane Modules 70
2.1.3 Planning and Operation of Membrane Bioreactors 82
2.1.3.1 Design 82
2.1.3.2 Mechanical Design and Planning 87
2.1.3.3 Operation 89
2.1.4 Investments and Operating Costs 92
2.1.4.1 Investments 92
2.1.4.2 Operating and Maintenance Costs 94
2.2 Concrete Examples of Membrane Bioreactors 95
2.2.1 Waste Water Treatment Plants with Microfiltration Membrane Installations in Germany 98
2.2.1.1 Seelscheid Waste Water Treatment Plant and Training Centre 98
2.2.1.2 Büchel Pilot Plant 101
2.2.1.3 Richtheim Waste Water Treatment Plant 103
2.2.1.4 Eitorf Waste Water Treatment Plant (Commissioning) 104
2.2.1.5 Xanten-Vynen Waste Water Treatment Plant (Commissioning) 106
2.2.1.6 Piene Waste Water Treatment Plant (in Planning Stage) 107
2.2.1.7 Rurberg-Woffelsbach and Konzen Waste Water Treatment Plants (Commissioned) 108
2.2.1.8 Kohlfurth Waste Water Treatment Plant, Process Water Treatment 109
2.2.1.9 Dormagen Waste Water Treatment Plant, Process Water Treatment (Commissioned) 110
2.2.2 Installations Outside of Germany with Microfiltration Membranes 111
2.2.2.1 Glasgow Waste Water Treatment Plant, Scotland 112
2.2.2.2 Ebisu Prime Square Building Waste Water Treatment Plant, Japan 114
2.2.2.3 St. Peter ob Judenburg Waste Water Treatment Plant, Austria 115
2.2.3 Waste Water Treatment Plants in Germany with Ultrafiltration Membranes 116
2.2.3.1 Nordkanal Waste Water Treatment Plant 116
2.2.3.2 Monheim Waste Water Treatment Plant 118
2.2.3.3 Markranstädt Waste Water Treatment Plant 121
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2.2.3.4 Rödingen Waste Water Treatment Plant 123
2.2.3.5 Schramberg-Waldmössingen Waste Water Treatment Plant 125
2.2.3.6 Knautnaundorf Waste Water Treatment Plant 127
2.2.3.7 Simmerath Pilot Plant 128
2.2.3.8 St. Wendel Golf Course 130
2.2.3.9 Glessen Waste Water Treatment Plant (Planning Stage) 132
2.2.4 Installations Outside of Germany with Ultrafiltration Membranes 133
2.2.4.1 Pilot Plants at the Beverwijk Waste Water Treatment Plant, The Netherlands 134
2.2.4.2 Varsseveld Waste Water Treatment Plant, The Netherlands 136
2.2.4.3 Brescia Waste Water Treatment Plant, Italy 137
2.2.4.4 Säntis Waste Water Treatment Plant, Switzerland 139
2.3 Small Waste Water Treatment Plants, Mobile Installations and
Ships Waste Water Treatment with Membrane Technology 140
2.3.1 Busse-MF Installation from the Company Busse 140
2.3.2 UltraSept Installation from the Company Mall 142
2.3.3 Small Waste Water Treatment Plant for 4 PE in North-Rhine Westphalia 143
2.3.4 Kreditanstalt für Wiederaufbau (KfW), Service Water Treatment 143
2.3.5 Small Waste Water Treatment Plant MembraneClearBox™ and Huber HoneyComb™
from the Company Huber AG 144
2.3.6 Mobile Installations for the Use in Military Camps 146
2.3.7 Ships’ Waste Water Treatment Plants with Membrane Technology 147
2.3.8 Cruise Liner Queen Mary 2 148
2.3.9 Grey and Black Water Treatment on Ships 150
2.4 Downstream Membrane Stage for Waste Water Disinfection 152
2.4.1 Process Description and Fields of Application 152
2.4.2 Membrane Modules Used 152
2.4.3 Operating Experience 153
2.4.4 Large-Scale Applications in Germany for Waste Water Disinfection by Ultrafiltration 153
2.4.4.1 Geiselbullach Waste Water Treatment Plant 154
2.4.4.2 Merklingen Waste Water Treatment Plant 155
2.4.4.3 Bondorf-Hailfingen Waste Water Treatment Plant 157
2.4.5 Large-Scale Applications Outside of Germany for Waste Water Disinfection by Ultrafiltration 159
2.4.5.1 Torreele, Belgium 159
2.4.5.2 Katowice Treatment Plant, Poland 161
2.4.5.3 Bedok Waste Water Treatment Plant, Singapore 162
2.5 Example for the Design of a Membrane Bioreactor 163
2.5.1 Design Basis 163
2.5.2 Interpretation of the ARA-BER Calculation According to the Design Recommendations for
Membrane Bioreactors 164
2.5.3 Design of the Membrane Filtration Stage 165
2.5.4 Printout of the Design Results with ARA-BER 166
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3 Membrane Technology in Industrial Waste Water Treatment 167
3.1 Brief Overview 168
3.2 Objectives and Applications in Different Industrial Branches 170
3.3 Decision Criteria 172
3.4 Economic Efficiency of Membrane Installations in Industrial
Waste Water Treatment 174
3.5 Sample Applications of Plants in Germany 177
3.5.1 Food Industry 179
3.5.1.1 Potato Starch Production 180
3.5.1.1.1 Food Industry, Emsland Stärke GmbH 181
3.5.1.2 Malt Houses 182
3.5.1.2.1 Malthouse Durst Malz – H. Durst Malzfabriken GmbH & Co. KG 183
3.5.1.3 Food Industry, BEECK Feinkost GmbH & Co. KG 184
3.5.2 Printing Industry, Peter Leis 185
3.5.3 Paper Mills 186
3.5.3.1 Paper Mill Palm, Works Eltmann 187
3.5.4 Textile Industry 188
3.5.4.1 Textile Industry, Drews Meerane 189
3.5.4.2 Silk Weaving Mill PONGS 191
3.5.4.3 Textile Finishing Works Gerhard van Clewe GmbH & Co. KG 193
3.5.5 Fibre Industry, Vulcanized Fibre 195
3.5.6 Plastics Industry, Troplast 197
3.5.7 Laundries 198
3.5.7.1 Laundry Alsco 198
3.5.7.2 Textile Service Mewa GmbH 201
3.5.8 Metal Processing Industry 203
3.5.8.1 Metal Processing Industry, Rasselstein Hoesch GmbH 204
3.5.8.2 Metal Processing Industry, Faurecia Bertrand Faure Sitztechnik GmbH & Co. KG 205
3.5.8.3 Metal Processing Industry, Electroplating Enterprise Rudolf Jatzke 206
3.5.8.4 Metal Processing Industry, Wieland Werke AG 208
3.5.9 Treatment of Waste Water from Car Painting 210
3.5.9.1 Treatment of Waste Water from Car Painting, DaimlerChrysler AG 210
3.5.9.2 Treatment of Paint Waste Water from the Production of Spare Parts in the Ford Works,
Cologne 211
3.5.10 Pharmaceutical Industry, Schering 213
3.5.11 Miscellaneous 215
3.5.11.1 Landfill Leachate 215
3.5.11.1.1 Alsdorf-Warden Landfill 218
3.5.11.2 Fish Hatchery 220
3.5.11.3 Power Stations, Dresden Gas and Steam Turbine Heating Power Station (GuD) 221
3.5.11.4 De-oiling of Bilge Water 223
3.5.11.5 Swimming Pools 225
3.5.11.5.1 Swimming Pool, Aquana Freizeitbad GmbH & Co. KG 225
3.5.11.5.2 Swimming Pool, Freizeitbad Copa Ca Backum 227
3.6 Sample Applications of Plants Outside of Germany 229
3.6.1 Food Industry 230
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3.6.1.1 Muesli Production at the Kellogg Company, Great Britain 230
3.6.1.2 Primary Starch Production at Raisio Chemicals, Belgium 232
3.6.1.3 Dairygold Food Products, Ireland 233
3.6.1.4 Dairy Crest Limited, Great Britain 235
3.6.1.5 Malthouse Sobelgra n. v., Belgium 236
3.6.2 Laundry Massop, The Netherlands 239
3.6.3 Pharmaceutical Industry, Penicillin Production at the Company Sandoz/Biochemistry, Spain 240
3.6.4 Miscellaneous 242
3.6.4.1 Animal Carcass Disposal Plant of SARIA Bio-Industries, France 242
3.6.4.2 Mechanical-Biological Waste Treatment Plant 244
3.6.4.2.1 Waste Disposal at the Company TIRME, Spain 244
4 Instructions and Standards in Membrane Technology 247
5 Summary and Outlook 251
6 References 253
A Annex 263
A.1 Addresses (mentioned in the concrete examples) 264
A.1.1 Locations of the membrane systems in Germany 264
A.1.2 Planners and manufacturers of installations, membrane manufacturers, Consulting Engineers 268
A.1.3 Scientific assistance for the realization of this publication 272
A.1.4 Other institutions and persons having contributed to the contents 274
A.1.5 Other information sources in the field of membrane technology 275
A.2 Possibilities for promotion 276
A.2.1 Development programs and advisory service of the Federal Government 276
A.2.2 Development programs of the federal states 277
A.2.3 Development programs of the EU in the field of pollution control and water management 282
A.3 Short check lists for Figure 2-1 284
A.4 Short check lists for Figure 3-1 286
A.5 Work report of the ATV-DVWK working group
IG-5.5 “Membrane Technology”: Treatment of industrial waste water and
process water by membrane processes and membrane bioreactor processes 288
Part I Membrane processes 288
A.5.1 Introduction 288
A.5.2 Choice of a membrane process 291
A.5.2.1 Determination of the necessary molecular separation size 291
A.5.2.2 Determination of the membrane material 291
A.5.2.3 Determination of the membrane module 293
A.5.2.4 Determination of the operating mode of membrane installations 295
A.5.3 Examples for the use of membrane processes 296
A.5.4 Planning of membrane installations 296
A.5.4.1 Acquisition of basic data 296
A.5.4.2 Planning and design 296
A.5.4.2.1 Preliminary laboratory tests 296
List of contents 1
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A.5.4.2.2 On-site pilot tests 297
A.5.4.2.3 Planning of the installation 297
A.5.5 Assessment criteria for the choice of a membrane installation 298
A.5.5.1 Technical assessment of a membrane process concerning employment and completeness 298
A.5.5.1.1 Definition of the terms of reference 298
A.5.5.1.2 Material and mass fluxes during operation of a membrane installation 298
A.5.5.1.3 Utilization or discharge of the resulting products 299
A.5.5.1.4 Pretreatment 299
A.5.5.1.5 Technical realization 299
A.5.5.1.6 Redundancies 299
A.5.5.1.7 References/similar applications 299
A.5.5.2 Operating costs 299
A.5.5.2.1 Equipment 299
A.5.5.2.2 Auxiliaries 299
A.5.5.2.4 Service life and replacement of membranes 299
A.5.5.3 Change of the conditions during operation of the installation 300
A.5.5.4 Other items 300
A.5.5.4.1 Failures 300
A.5.5.4.2 Preliminary tests 300
A.5.6 Questionnaire for the acquisition of process data 300
A.5.6.1 Description of the separation problem to be solved with the help of a membrane process 300
A.5.6.2 Concerning the assessment or the integration of a membrane process into an
overall treatment concept 301
A.5.6.3 Sizing of the installation 301
A.5.6.4 Requirements for the construction of the membrane installation 301
Part II Aerobic membrane bioreactor processes 301
A.5.7 General information 301
A.5.8 Construction 302
A.5.8.1 Arrangement 302
A.5.8.1.1 Immersed membrane modules 302
A.5.8.1.2 Dry-arranged membrane modules 302
A.5.8.2 Control of the covering layer 303
A.5.8.2.1 Control of the covering layer in immersed systems 303
A.5.8.2.2 Covering layer control in dry-arranged systems 303
A.5.8.2.3 General facts 304
A.5.8.3 Cleaning strategies 304
A.5.9 Requirements for the influent 306
A.5.9.1 General information 306
A.5.9.2 Mechanical pretreatment 306
A.5.9.3 Mixing and equalizing tank 307
A.5.9.4 Calcium concentration 307
A.5.9.5 Iron and aluminium content 307
A.5.10 Instructions for the design of membrane bioreactors 307
A.5.10.1 General information 307
A.5.10.2 Space requirements 308
A.5.10.3 Elimination rates 308
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A.5.10.4 Aeration 309
A.5.10.5 Hydraulics 309
A.5.10.5.1 Flexibility 309
A.5.10.5.2 Recirculation 309
A.5.10.6 Influence of the temperature 310
A.5.11 Specific features of membrane bioreactors 310
A.5.11.1 Sludge features 310
A.5.11.1.1 Characterization of the sludge 310
A.5.11.1.2 Rheological properties 310
A.5.11.1.3 Excess sludge production 311
A.5.11.1.4 Sludge treatment 311
A.5.11.1.5 Foam development 311
A.5.12 Economic efficiency 312
A.5.12.1 Definition of economic efficiency 312
A.5.12.2 Investment/capital costs 312
A.5.12.3 Operating costs 313
A.5.12.4 Comparison of cost-relevant factors 314
A.5.13 Examples in the field of industrial waste water (Europe) 315
A.5.14 Literature 315
A.6 2nd Work report of the DWA Committee of Experts KA-7
“Membrane bioreactor process“ from 19th January 2005 317
A.6.1 Introduction 317
A.6.2 Description of the membrane bioreactor process 318
A.6.3 Instructions for planning and design 322
A.6.4 Sludge treatment 326
A.6.5 Chemical cleaning of the membrane modules 328
A.6.6 Energy demand 329
A.6.7 Upgrading of existing municipal waste water treatment plants 331
A.6.8 Instructions for start-up 332
A.6.9 Costs 333
A.6.10 Annual costs 336
A.6.10.1 Loan servicing and membrane replacement 336
A.6.10.2 Operating costs 336
A.6.11 Final remark 336
A.6.12 Advantages and risks of the membrane bioreactor process 337
A.6.12.1 General facts 337
A.6.13 Glossary 337
A.6.14 Literature 341
A.7 Large-scale membrane installations for drinking water treatment in Germany 343
A.8 Glossary 344
A.9 List of abbrevations 346
List of figures 1
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1 Basics of Membrane Technology 27
Figure 1-1 Operating principle of micro- and ultrafiltration membranes 28
Figure 1-2 The different fields of application of membrane processes 29
Figure 1-3 Size of typical waste water constituents and the pore size of membranes applied 30
Figure 1-4 Idealized representation of a pore membrane and a solution-diffusion membrane
[according to MELIN 1999] 31
Figure 1-5 Classification of membranes [according to RAUTENBACH 1997] 35
Figure 1-6 Scanning electron micrographs of cross-sections of different membranes 37
Figure 1-7 Top view of the active layer of a polyethylene membrane (MF/UF) [AGGERVERBAND 2002] 37
Figure 1-8 Top view of the broken edge of a polyethylene membrane (MF/UF), the active layer is visible
[AGGERVERBAND 2002] 37
Figure 1-9 Membrane and module forms 38
Figure 1-10 Tube modules [photo: WEHRLE WERK AG] 40
Figure 1-11 Capillary or hollow-fibre modules [photo: KOCH MEMBRANE SYSTEMS] 41
Figure 1-12 Spiral-wound modules [schematic drawing: N. N. 2001], [photo: NADIR FILTRATION GMBH] 42
Figure 1-13 Cushion module [schematic drawing and photo: ROCHEM UF SYSTEME GMBH] 43
Figure 1-14 Disc-tube module (DT module) [PALL 2001] 44
Figure 1-15 New Multibore capillaries from the company inge AG [photo: INGE AG] 45
Figure 1-16 From the membrane element to the membrane stage 46
Figure 1-17 Series connection of modules [according to BAUMGARTEN 1998] 46
Figure 1-18 Parallel connection of modules [according to BAUMGARTEN 1998] 47
Figure 1-19 Arrangement of several modules according to the fir tree structure
[according to RAUTENBACH 1997] 47
Figure 1-20 Schematic representation of a membrane in cross-flow- and dead-end filtration
[according to MELIN 1999] 49
Figure 1-21 Filtration intervals in dead-end operation [according to RAUTENBACH 1997] 49
Figure 1-22 Schematic overview of the filtration resistances on the membrane surface and inside the membrane
[KRAMER, KOPPERS 2000] 51
Figure 1-23 Effect of membrane cleaning on the flow at constant pressure 53
Figure 1-24 Molar masses of selected natural organic constituents in domestic waste water 58
Figure 1-25 Molar masses of selected organic trace substances 59
2 Membrane Technology in Municipal Waste Water Treatment 61
Figure 2-1 Background – planning – operation of a municipal membrane bioreactor, contents of the chapter
“Membrane technology in municipal waste water treatment“ 63
Figure 2-2 Conventional waste water treatment according to the activated sludge process and possibilities for
the arrangement of a membrane stage at municipal waste water treatment plants [OHLE 2001] 64
Figure 2-3 Flow sheet of a waste water treatment plant with membrane bioreactor process and downstream
membrane stage 65
Figure 2-4 Comparison of the germ load in the effluent of waste water treatment plants [BAUMGARTEN,
BRANDS 2002] 68
Figure 2-5 Schematic representation of the space requirements of a conventional activated sludge plant
(edged in blue) and of a membrane bioreactor (edged in red), example: Nordkanal waste water
treatment plant [ERFTVERBAND 2002] 69
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Figure 2-6 ZeeWeed®-module from the company ZENON 70
Figure 2-7 Arrangement of several ZeeWeed®-modules ZW 1000 in a cassette [photo: ZENON 2004] 71
Figure 2-8 Plate module from the company Kubota 71
Figure 2-9 Basic schematic of the plate module “double-decker” from the company Kubota
[AGGERWASSER GMBH 2004] 72
Figure 2-10 PURON module and module component [photo: PURON AG] 73
Figure 2-11 Membrane module from Martin Systems AG 74
Figure 2-12 Huber VRM® process [photos: HANS HUBER AG, MARTIN SYSTEMS AG] 75
Figure 2-13 Huber VUM® process [HANS HUBER AG] 76
Figure 2-14 Membrane element and membrane module from the company Mitsubishi [photo: ENVICARE®] 76
Figure 2-15 Plate module from the company A3 GmbH [photo: A3 GMBH] 77
Figure 2-16 Membrane module from US Filter Corporation [photo: US FILTER CORPORATION 2004] 78
Figure 2-17 Membrane module from the Keppel Seghers Belgium [photo: KEPPEL SEGHERS BELGIUM NV] 78
Figure 2-18 Membrane system from Weise Water Systems GmbH & Co. KG
[WEISE WATER SYSTEMS GMBH&CO. KG] 79
Figure 2-19 Ceramic plate membranes from the company ItN Nanovation [photo: ItN NANOVATION] 80
Figure 2-20 Membrane module and configuration of the modules in the rack with underlying aeration device
[photos: ItN NANOVATION] 80
Figure 2-21 Basic layout sketch of the rotation disc filter 81
Figure 2-22 Modules of the rotation disc filter in laboratory scale [photo: FRAUNHOFER IGB] 81
Figure 2-23 Specific excess sludge production in membrane bioreactors [ATV-DVWK 2000a] 83
Figure 2-24 Oxygen transfer coefficient (�-values) of the Rödingen and Markranstädt waste water treatment
plants with fine-bubble diffuser aeration [CORNEL ET AL. 2001] 86
Figure 2-25 View and principle of a screening facility for membrane bioreactors (Markranstädt waste water
treatment plant) [HUBER 2002, STEIN 2002a] 87
Figure 2-26 Energy demand of a membrane bioreactor (8,000 PE) with simultaneous aerobic sludge
stabilization [STEIN ET AL. 2001] 91
Figure 2-27 Development of membrane replacement costs [ISA 2002; CHURCHHOUSE, WILDGOOSE 2000] 94
Figure 2-28 Flow sheet of the Seelscheid waste water treatment plant [according to AGGERVERBAND 2004] 99
Figure 2-29 Membrane installation at the Seelscheid waste water treatment plant
[photos: AGGERVERBAND 2004] 99
Figure 2-30 Existing sand filter tanks, to be used for the training installations [photo: AGGERVERBAND 2004] 100
Figure 2-31 Flow sheet of the training installations [according to AGGERVERBAND 2004] 100
Figure 2-32 View of the Büchel pilot plant [photo: ISA RWTH AACHEN] 101
Figure 2-33 Flow sheet of the Büchel pilot plant [BAUMGARTEN 2001b] 101
Figure 2-34 Flow sheet of the membrane bioreactor [according to BAYERISCHES LANDESAMT FÜR
WASSERWIRTSCHAFT 2004] 103
Figure 2-35 Flow sheet of the Eitorf waste water treatment plant [according to GEMEINDEWERKE EITORF 2004] 104
Figure 2-36 Eitorf waste water treatment plant with covered membrane tanks between the buildings in the
foreground 105
Figure 2-37 Membrane installation in container construction for the Xanten-Vynen waste water treatment plant
[photo: A3 GMBH] 106
Figure 2-38 Flow sheet of the Xanten-Vynen waste water treatment plant, including the planned membrane
bioreactors [according to LINEG 2004] 106
Figure 2-39 Flow sheet of the membrane bioreactor [according to CITY OF GUMMERSBACH 2004] 107
Figure 2-40 Flow sheet of the Kohlfurth waste water treatment plant [according to WUPPERVERBAND 2004] 109
List of figures 1
15
Figure 2-41 Flow sheet of the Dormagen waste water treatment plant [according to CITY OF DORMAGEN 2004] 110
Figure 2-42 Aerial photograph of the Swanage waste water treatment plant [photo: AQUATOR GROUP] 111
Figure 2-43 Flow sheet of the Glasgow sludge treatment plant [according to AGGERWASSER GMBH 2004] 112
Figure 2-44 Top view of the sludge treatment plant and of a tank of the membrane installation
[photo: AGGERWASSER GMBH 2001] 113
Figure 2-45 Ebisu Prime Square Building [photo: AGGERWASSER GMBH 2004] 114
Figure 2-46 Waste water treatment plant in the basement of the Ebisu Prime Square Building
[photo: AGGERWASSER GMBH 2004] 114
Figure 2-47 Flow sheet of the waste water treatment plant [according to AGGERWASSER GMBH 2004] 114
Figure 2-48 Flow sheet of the St. Peter ob Judenburg waste water treatment plant
[according to ENVICARE 2002] 115
Figure 2-49 St. Peter ob Judenburg waste water treatment plant [photos: ENVICARE] 116
Figure 2-50 Rotary screen of the fine screen installation 117
Figure 2-51 Flow sheet of the Nordkanal waste water treatment plant [according to ERFTVERBAND 2004] 117
Figure 2-52 Membrane installation at the WWTP Nordkanal 118
Figure 2-53 Monheim waste water treatment plant [photo: BAYERISCHES LANDESAMT FÜR
WASSERWIRTSCHAFT (Bavarian Office for Water Management) 2004] 119
Figure 2-54 Flow sheet of the Monheim waste water treatment plant [according to BAYERISCHES
LANDESAMT FÜR WASSERWIRTSCHAFT 2004] 119
Figure 2-55 Module cassettes during in-air cleaning [photo: CITY OF MONHEIM 2004] 120
Figure 2-56 Process stages at the Markranstädt waste water treatment plant [STEIN 2002a]. 121
Figure 2-57 Process stages at the Markranstädt waste water treatment plant [STEIN 2002a] 122
Figure 2-58 Flow sheet of the Rödingen waste water treatment plant 124
Figure 2-59 View into the two filtration lines during fitting of the ZeeWeed™ cassettes [photo: ERFTVERBAND] 124
Figure 2-60 Schramberg-Waldmössingen waste water treatment plant [photo: STADTWERKE SCHRAMBERG
(municipal utilities) 2004] 125
Figure 2-61 Flow sheet of the Schramberg-Waldmössingen waste water treatment plant [according to
STADTWERKE SCHRAMBERG 2004] 126
Figure 2-62 Membrane installation at the Schramberg-Waldmössingen waste water treatment plant
[photos: STADTWERKE SCHRAMBERG 2004] 126
Figure 2-63 Flow sheet of the Simmerath demonstration plant [according to WVER 2004] 128
Figure 2-64 Membrane installation at the Simmerath waste water treatment plant [photos: PURON AG 2003] 129
Figure 2-65 Flow sheet of the golf course St. Wendel waste water treatment plant [according to ST. WENDEL] 130
Figure 2-66 Module rack at the golf course St. Wendel waste water treatment plant [photos: ItN NANOVATION] 131
Figure 2-67 Flow sheet of the Glessen waste water treatment plant [according to ERFTVERBAND 2004] 132
Figure 2-68 Aerial photograph and flow sheet of the Lowestoft waste water treatment plant [ZENON 2002] 133
Figure 2-69 Photos of the pilot installations and membrane modules at the test field of the Beverwijk waste
water treatment plant [DHV 2004] 135
Figure 2-70 Flow sheet of the Varsseveld waste water treatment plant [according to DHV 2004] 136
Figure 2-71 Flow sheet of the Brescia waste water treatment plant [according to ZENON GMBH 2004] 137
Figure 2-72 Aerial photograph of the Brescia waste water treatment plant [photo: ZENON GMBH 2004] 138
Figure 2-73 View and flow sheet of the membrane bioreactor according to the ZenoGem™ process on the Säntis
[ZENON 2002] 139
Figure 2-74 View of the Busse MF small waste water treatment plant (formerly BioMIR™) [BUSSE 2002] 140
Figure 2-75 Flow sheet of a Busse-MF installation [BUSSE 2002] 141
List of figures1
16
Figure 2-76 Schematic representation of the UltraSept installation from the company Mall [MALL 2002] 142
Figure 2-77 Grey water treatment plant at KfW 143
Figure 2-78 Membrane installation for the treatment of service water in the cellar of KfW
[WEISE WATER SYSTEMS GMBH] 144
Figure 2-79 Plot plan of a small waste water treatment plant with membrane technology installed in a
multicompartment septic tank [HUBER AG 2004] 145
Figure 2-80 Small waste water treatment plant MembraneClearBox™ from Huber AG [photos: HUBER AG 2004] 145
Figure 2-81 Transportation of the container plant by an emergency vehicle and schematic representation of
the plant [A3 GMBH 2004] 146
Figure 2-82 View of a MEMROD ship’s waste water treatment plant according to the membrane bioreactor
process for 250 persons [VA TECH WABAG 2002] 148
Figure 2-83 Ultrafiltration module Pleiade™ for waste water treatment on Queen Mary 2
[photo: ORELIS SA 2004] 148
Figure 2-84 Photo of the Queen Mary 2 149
Figure 2-85 Flow sheet of the waste water treatment plan of Queen Mary 2 [according to ORELIS SA 2004] 149
Figure 2-86 Flow sheet of waste water treatment according to the two-stream solution
[according to ROCHEM UF 2004] 150
Figure 2-87 Membrane bioreactor BioFilt with three lines at 4.5 m3 of permeate per day each [ROCHEM UF 2004] 151
Figure 2-88 Low-pressure reverse osmosis for grey water treatment for 600 m3 of permeate per day
[photo: ROCHEM UF 2004] 151
Figure 2-89 Flow sheet of the Geiselbullach waste water treatment plant [according to AMPERVERBAND 2004] 154
Figure 2-90 Treatment installation at the Geiselbullach waste water treatment plant
[photos: AMPERVERBAND 2002] 155
Figure 2-91 Flow sheet of the Merklingen waste water treatment plant [according to RP TÜBINGEN 2004] 155
Figure 2-92 Pressure tubes of the ultrafiltration plant at the Merklingen waste water treatment plant
[RP TÜBINGEN 2004] 156
Figure 2-93 Flow sheet of the Bondorf-Hailfingen waste water treatment plant [according to BONDORF-
HAILFINGEN WASTE WATER UNION 2004] 158
Figure 2-94 Membrane installation at the Bondorf-Hailfingen waste water treatment plant under construction
[photos: BONDORF-HAILFINGEN WASTE WATER UNION 2004] 158
Figure 2-95 Flow sheet of the Torreele treatment plant [according to ZENON GMBH 2004] 160
Figure 2-96 Flow sheet of the ultrafiltration installation for process water treatment in Katowice
[according to ZENON GMBH 2004] 161
Figure 2-97 Flow sheet of the treatment plant [according to ZENON GMBH 2004] 162
Figure 2-98 General view of the treatment plant [photo: ZENON GMBH 2004] 163
Figure 2-99 Ultrafiltration membrane installation [photo: ZENON GMBH 2004] 163
3 Membrane Technology in Industrial Waste Water Treatment 167
Figure 3-1 Motive – planning – operation of a membrane installation, overview of the contents of the chapter
“Membrane technology in industrial waste water treatment” 169
Figure 3-2 Objectives and economic interests for the use of a membrane installation in industrial waste water
treatment 170
Figure 3-3 How to proceed in the planning of an installation for industrial waste water treatment 173
Figure 3-4 Factors influencing the economic efficiency of membrane installations 175
Figure 3-5 Flow chart of potato starch production 180
List of figures 1
17
Figure 3-6 Flow chart of the treatment of process- and potato pulp water at Emsland Stärke GmbH
[according to LOTZ 2000] 181
Figure 3-7 Reverse osmosis installation at Durst Malzfabriken GmbH & Co. KG, Gernsheim [LINDEMANN 2001] 183
Figure 3-8 Flow chart of the waste water treatment at BEECK Feinkost GmbH [according to
KOCH-GLITSCH GMBH 2001] 184
Figure 3-9 Ultrafiltration installation at the Grafische Handelsvertretung Peter Leis [LEIS IN EFA 2000] 186
Figure 3-10 Nanofiltration installation at the paper mill Palm, works Eltmann (left) [SCHIRM 2001] and detail of
the tube module arrangement as feed-and-bleed structure (right) [according to SCHIRM 2001] 188
Figure 3-11 Flow sheet of the waste water treatment and processing plant [according to ZENON GMBH 2004] 190
Figure 3-12 Conversion of the waste water treatment plant at PONGS Textil GmbH 191
Figure 3-13 Flow sheet of the membrane bioreactor of the company PONGS [according to A3 GMBH 2004] 192
Figure 3-14 Ultrafiltration installation at the textile finishing plant van Clewe [BÖTTGER 2001] 194
Figure 3-15 Flow sheet of the process water treatment at the vulcanized fibre works GmbH & Co. KG
[AMAFILTER 2001] 195
Figure 3-16 Reverse osomosis installation at the vulcanized fibre works Ernst Krüger GmbH & Co. KG
[photo: AMAFILTER] 196
Figure 3-17 Ultrafiltration installation at the company HT Troplast AG [photo: HT TROPLAST] 197
Figure 3-18 Flow sheet of the waste water treatment process in the laundry ALSCO [according to
WEHRLE UMWELT GMBH 2004] 199
Figure 3-19 Membrane installation in the laundry Alsco [photos: WEHRLE UMWELT GMBH 2004] 200
Figure 3-20 Flow sheet of the treatment plant of Textile Service Mewa GmbH [according to ENVIRO CHEMIE 2004] 201
Figure 3-21 Ultrafiltration plant at Textile Service Mewa [photo: ENVIRO CHEMIE 2004] 202
Figure 3-22 Nanofiltration plant at Textile Service Mewa [photo: ENVIRO CHEMIE 2004] 202
Figure 3-23 Ultrafiltration installation at the company Rasselstein Hoesch [photo: MFT GMBH] 204
Figure 3-24 Ultrafiltration installation at the company Faurecia, Bertrand Faure Sitztechnik GmbH & Co. KG
[KASTEN 2001] 205
Figure 3-25 Mode of operation of the electrolysis membrane [SCHMIDT 2002] 207
Figure 3-26 Ultrafiltration installation at the works Werk Langenberg of Wieland Werke AG [MUNLV 2001] 209
Figure 3-27 Ultrafiltration installation in the DaimlerChrysler works at Düsseldorf [HARMEL 2001] 210
Figure 3-28 Flow sheet of paint-spraying [IMB +FRINGS WATERSYSTEMS GMBH 2004] 211
Figure 3-29 Nanofiltration plant at the Ford works Cologne [photo: IMB+FRINGS WATERSYSTEMS GMBH 2004] 212
Figure 3-30 Aerial photograph of the waste water treatment plant at Schering AG [photos: SCHERING AG 2004] 213
Figure 3-31 Flow sheet of the waste water treatment plant [according to SCHERING AG 2004] 214
Figure 3-32 Optical inspection of a membrane module [photo: SCHERING AG 2004] 215
Figure 3-33 Process combination according to the state of the art for the treatment of landfill leachate without
using membrane processes [ROSENWINKEL, BAUMGARTEN 1998] 216
Figure 3-34 Process combination according to the state of the art for the treatment of landfill leachate using
membrane processes with and without biological pretreatment [completed according to
ROSENWINKEL, BAUMGARTEN 1998] 216
Figure 3-35 Reverse osmosis installation at the landfill Alsdorf-Warden [MAURER 2001] 218
Figure 3-36 Structure of the composite membrane [MAURER 2001] 219
Figure 3-37 Flow sheet of a circuit installation for the treatment of waste water from fish hatchery
[UMWELTBUNDESAMT 2004] 221
Figure 3-38 Flow sheet of the RÖKU process [according to DPC 1997] 222
Figure 3-39 Ultrafiltration unit for the RÖKU process [photo: THERM-SERVICE] 223
Figure 3-40 Flow sheet of bilge de-oiling [according to DEUTSCH 2001] 224
List of figures1
18
Figure 3-41 Water recirculation and treatment at the Aquana Freizeitbad [according to DEGEBRAN®] 226
Figure 3-42 Water treatment at the Freizeitbad Copa Ca Backum [according to L. V. H. T. 2001] 228
Figure 3-43 Flow sheet of the waste water treatment plant at the Kellogg Company in Manchester
[according to WEHRLE UMWELT GMBH 2004] 231
Figure 3-44 Cross-flow ultrafiltration at the Kellog Company in Manchester [photo: WEHRLE UMWELT
GMBH 2004] 231
Figure 3-45 Flow sheet of the membrane bioreactor at Raisio Chemicals [according to HUBER AG 2004] 232
Figure 3-46 Huber VRM® process (rotating modules) [photos: HUBER AG 2004] 232
Figure 3-47 Flow sheet of the waste water treatment plant at Dairygold Food Products, Ireland
[according to WEHRLE UMWELT GMBH 2004] 234
Figure 3-48 Complete plant at Dairygold Food Products with the membrane installation in the foreground
[WEHRLE UMWELT GMBH 2004] 234
Figure 3-49 Flow sheet of the waste water treatment at Dairy Crest, Great Britain [according to
WEHRLE UMWELT GMBH 2004] 236
Figure 3-50 Aerial photograph of the malthouse Sobelgra in the Antwerpen harbour [photo: PURON AG] 237
Figure 3-51 Flow sheet of the company-owned waste water treatment plant of the company Sobelgra
[according to PURON AG] 238
Figure 3-52 Schematic representation of the membrane bioreactor (left) and membrane modules (right)
[photo: PURON AG] 238
Figure 3-53 Reverse osmosis installation at the laundry Massop, Kerkrade [ROTH 2001] 239
Figure 3-54 Flow sheet of the membrane bioreactor in Barcelona [according to AGGERWASSER GMBH 2004] 241
Figure 3-55 Membrane bioreactor and membrane modules under construction at the company Sandoz in Spain
[photos: AGGERWASSER GMBH 2004] 241
Figure 3-56 Flow sheet of the membrane bioreactor at SARIA Bio-Industries in Bayet [according to
ZENON GMBH 2004] 243
Figure 3-57 General view of the membrane bioreactor of the animal carcass disposal plant in Bayet
[photo: ZENON GMBH 2004] 243
Figure 3-58 Container with fitted modules at SARIA Bio-Industries in Bayet [photo: ZENON GMBH 2004] 243
Figure 3-59 Flow sheet of the waste water treatment plant at the company TIRME, Spain [according to
WEHRLE UMWELT GMBH 2004] 245
Figure 3-60 Waste water treatment plant at the company TIRME [photos: WEHRLE UMWELT GMBH 2004] 245
A Annex 263
Figure A-1 Schematic representation of the basic principle of a membrane process 289
Figure A-2 Classification of membrane and filtration processes 289
Figure A-3 Cross-section of a phase-inversion membrane, example: UF hollow-fibre membrane 292
Figure A-4 Composite membrane 292
Figure A-5 Front view of a tube module with 5.5 mm tubular membranes [photo: X-FLOW] 294
Figure A-6 View of a cushion module [type ROCHEM FM] 294
Figure A-7 Principle of a spiral-wound module 295
Figure A-8 Material and mass fluxes during operation of a membrane installation 298
Figure A-9 Schematic comparison of the conventional activated sludge process with the membrane
bioreactor process 302
Figure A-10 Arrangement of the immersed membrane modules in the aerobic section of the
activated sludge tank 303
Figure A-11 Arrangement of the immersed membrane modules in an external filtration tank 303
List of figures 1
19
Figure A-12 Membrane modules in dry arrangement 303
Figure A-13 Qualitative relationship between necessary membrane surface area, energy demand and flow 304
Figure A-14 Membrane filtration in dry arrangement 318
Figure A-15 Ways of configuring an immersed membrane filtration 319
Figure A-16 Schematic representation of different module constructions 320
Figure A-17 Typical operating modes of the membrane modules 321
Figure A-18 Influence of the solids concentrations on the �-value for fine-bubble pressure aeration installations 325
Figure A-19 Specific energy consumption of the Markranstädt WWTP [STEIN, KERKLIES 2003] 330
Figure A-20 Specific energy consumption of the KA Monheim WWTP [WEDI 2003] 331
Figure A-21 Example for the distribution of construction costs of a membrane bioreactor for approximately
300 m3/h [WEDI 2003] 334
Figure A-22 Orienting net cost guide values for the ready-for-use membrane filtration installation without
structural part [WEDI 2003] 335
List of tables1
20
1 Basics of Membrane Technology 27
Table 1-1 Pressure-driven membrane processes in waste water purification 31
Table 1-2 Characteristic features of micro- and ultrafiltration 32
Table 1-3 Characteristic features of nanofiltration 33
Table 1-4 Characteristic features of reverse osmosis 34
Table 1-5 Characteristic values, advantages and disadvantages of module types with tubular membranes 39
Table 1-6 Characteristic values, advantages and disadvantages of module types with flat membranes 39
Table 1-7 Formation of covering layers in membrane filtration [according to BAUMGARTEN 1998] 51
Table 1-8 Methods for reduction and removal of covering layers 52
Table 1-9 Examples of cleaning chemicals and their applications 54
Table 1-10 Molecular separation size and transmembrane pressure of pressure-driven membrane processes 55
Table 1-11 Data on the size of viruses and bacteria 56
Table 1-12 Molar masses of selected natural organic constituents in domestic waste water
[KOPPE, STOZEK 1999] 57
Table 1-13 Molar masses of selected organic trace substances [MUNLV 2004] 59
2 Membrane Technology in Municipal Waste Water Treatment 61
Table 2-1 Advantages of the membrane bioreactor process compared to the conventional activated sludge process 66
Table 2-2 Performance data of membrane bioreactor plants compared to conventional activated sludge plants
[DOHMANN ET AL. 2002] 67
Table 2-3 Cleaning methods 90
Table 2-4 Savings potentials and additional costs concerning the investments of membrane bioreactors
compared to conventional activated sludge plants 93
Table 2-5 Data of the large-scale membrane bioreactors treating municipal waste water in Germany,
as of December 2004 96
Table 2-6 Membrane bioreactors under construction or in planning stage in Germany, as of December 2005 97
Table 2-7 Minimum requirements, discharge consent and operating values of the Seelscheid waste water
treatment plant [according to AGGERVERBAND 2004] 98
Table 2-8 Input values for the design of the Eitorf membrane bioreactor [according to
GEMEINDEWERKE EITORF (municipal utilities) 2004] 104
Table 2-9 Demands on the effluent quality of the Rurberg-Woffelsbach and Konzen waste water treatment
plants [according to WVER 2004] 108
Table 2-10 Raw waste water and permeate quality [according to AGGERWASSER GMBH 2004] 114
Table 2-11 Influent and effluent concentrations of the waste water treatment plant 115
Table 2-12 Minimum requirements and discharge consent of the Nordkanal waste water treatment plant
[ERFTVERBAND 2004] 116
Table 2-13 Minimum requirements, discharge consent and operating values of the Monheim waste water
treatment plant [BAYERISCHES LANDESAMT FÜR WASSERWIRTSCHAFT 2004] 120
Table 2-14 Minimum requirements, discharge consent and operating values of the Markranstädt waste water
treatment plant [STEIN 2002a] 121
Table 2-15 Minimum requirements and discharge consent of the Rödingen waste water treatment plant
[according to ENGELHARDT ET AL. 2001] 123
Table 2-16 Discharge consent of the Simmerath waste water treatment plant [WVER 2004] 128
Table 2-17 Operating values of the membrane bioreactor in Simmerath [WVER 2004] 129
Table 2-18 Minimum requirements, discharge consent and operating values of the golf course St. Wendel
waste water treatment plant [CITY OF ST. WENDEL 2005] 130
List of tables 1
21
Table 2-19 Demands on the effluent quality of the Glessen waste water treatment plant
[according to ERFTVERBAND 2004] 132
Table 2-20 Key features of the individual pilot installations [DHV 2004] 134
Table 2-21 Raw waste water concentration, operating values and requirements of the Brescia waste water
treatment plant [ZENON GMBH 2004] 138
Table 2-22 Requirements for the effluent quality of small waste water treatment plants and measured effluent
values of the Busse-MF installation 141
Table 2-23 Characteristic values of different membrane modules for the filtration of effluents from the test
installations of Berliner Wasserbetriebe and the test installations at the Geiselbullach, Halfingen
and Merklingen waste water treatment plants 152
Table 2-24 Membrane installations for waste water disinfection in Germany 153
Table 2-25 Demands on the effluent quality and operating values of the Bondorf-Hailfingen waste water
treatment plant [BONDORF-HAILFINGEN WASTE WATER UNION 2004] 157
Table 2-26 Quality of the effluent of the Wulpen waste water treatment plant [ZENON GMBH 2004] 159
Table 2-27 Waste water quality at the inlet and outlet of the ultrafiltration installation for treatment of the
effluent of the Katowice WWTP after secondary clarification up to process water quality
[ZENON GMBH 2004] 161
Table 2-28 Design results according to the approach of the University Group (HSG) for a conventional waste
water treatment plant with TSBB = 12 g/l 164
Table 2-29 Determination of the necessary volumes, taking into account different requirements for the
design of membrane installations 164
3 Membrane Technology in Industrial Waste Water Treatment 167
Table 3-1 Objectives for the utilization of membrane technology in industrial waste water treatment 171
Table 3-2 Sequence of planning for a membrane installation [according to THEILEN 2000; PETERS 2001] 174
Table 3-3 Sample applications for the use of membrane technology in industrial waste water treatment
in Germany 178
Table 3-4 Quality of the recycling water 2 [ENVIRO CHEMIE 2004] 203
Table 3-5 Inflow values, effluent requirements and operating values of the plant [SCHERING AG 2004] 214
Table 3-6 Sample applications for the use of membrane technology in industrial waste water treatment
outside of Germany 229
A Annex 263
Table A-1 Contacts for development programs of the federal states and selected development programs
concerning “waste water avoidance, closed process water circuits“ 278
Table A-2 Membrane processes and their fields of application 291
Table A-3 Overview of the most current membrane materials for the different membrane processes 293
Table A-4 Features and fields of application of different module types 294
Table A-5 Membrane installations in West European industry 314
Table A-6 Characteristic data of designed membrane bioreactors [WEDI 2002a] 324
Table A-7 Studies on the dewaterability of excess sludge on a large-scale centrifuge 327
Table A-8 Membrane-specific annual cost shares 336
1
22
Introduction
23
What is membrane technology?
Membrane technology is a physical process for the sepa-
ration of material mixtures in which the membranes
function like a filter. The separated substances are neither
thermally nor chemically nor biologically modified. In
waste water treatment membrane technology is also used
in combination with other purification methods, e. g.
biological procedures.
Fields of application
World-wide the field of application of membrane techno-
logy is becoming more and more broad. While its begin-
nings lay in the field of water purification in the desali-
nation of sea and brackish water in arid zones, it is used
for decades also for the separation of valuable materials
from small water volumes, e. g. in biotechnology, in the
pharmaceutical and chemical industry, the metal-work-
ing industry and in the food and beverage industry.
In addition, membrane technology got accepted as effi-
cient and economic procedure for the treatment of high-
strength industrial waste water. Membrane technology
has been tested and applied for the last ten years for the
treatment of comparably low-loaded and big water volu-
mes in drinking water treatment as well as in municipal
waste water treatment (membrane bioreactor process).
Membrane processes are used in drinking water treatment
to improve the retention of particles and to remove micro-
organisms. Ultrafiltration is predominantly used in this
field because not only germs but also viruses are safely
retained. Membrane processes for drinking water prepara-
tion are not treated in detail in this publication. Existing
plants with membrane technology are listed in Annex A7.
The membrane processes microfiltration, ultrafiltration,
nanofiltration and reverse osmosis are classified accord-
ing to the size or molar mass of the separated substances.
Their different molecular separation sizes allow for the
choice of the suited process for the particular task. For
more complex tasks, the combination with other proces-
ses, e. g. biological or chemical processes, is a possibility.
In the same way, two membrane processes may be com-
bined.
Membrane processes in waste water treatment
Due to high efficiency and the possibility of saving costs,
membrane processes currently represent a proven alter-
native to classical procedures for many applications in
the waste water treatment.
The high purification efficiency of membrane processes,
in particular the combination of an activated sludge stage
with downstream micro- or ultrafiltration, makes it pos-
sible to meet the requirements of tertiary waste water
treatment that are legislated for the protection of surface-
and groundwater. Without membrane technology, these
requirements can often only be met by a combination of
different process stages (e. g. activated sludge stage, con-
ventional filtration, disinfection). By using membrane
technology, it is possible in certain cases to reduce the
costs of water supply and waste water treatment as well
as production costs.
Objectives in waste water treatment
In municipal and industrial waste water treatment, mem-
brane processes are applied to satisfy the following objec-
tives:
• retention
(e. g. of solid matter including biomass, of hazardous
material, of dissolved matter by reverse osmosis)
• purification
(e. g. for industrial water treatment, for disinfection by
retention of bacteria)
• concentration
(e. g. for the recycling of valuable substances)
• fractionation
(e. g. for separation into two or more components)
Introduction
Advantages of membrane technology in waste
water treatment
The membrane bioreactor process with immersed mem-
branes can be used for industrial as well as municipal
waste water treatment. Compared to conventional waste
water treatment processes (activated sludge stage, secon-
dary treatment, filtration, disinfection), it has many
advantages which also have economic effects:
• saving of the process stages secondary stage, sand filtra-
tion, UV disinfection,
• the very compact design; compared to the activation
process, the necessary activation volume is only
approx. 30 %,
• the higher purification efficiency by complete reten-
tion of particles and bacteria, and, depending on the
membrane process, also viruses,
• better removal of organic trace substances by a higher
sludge age and the establishing of special micro-orga-
nisms
• the possibility to arrange downstream an additional
membrane stage (nanofiltration or reverse osmosis) to
retain organic trace substances and possibly also dis-
solved substances.
Prospects
Further development and application of membrane tech-
nology in the field of water and waste water treatment
will continue in the next years. The growth forecasts
concerning world-wide application of membrane proces-
ses are approx. 10 – 15 % per year for waste water treat-
ment and about 20 % per year for drinking water treat-
ment (including sea water desalination). (Plants for drink-
ing water treatment existing in Germany are compiled in
Annex 7). Due to continuous development of membrane
materials and module constructions as well as process
design and process engineering, a still broader range of
applications is opened up.
Moreover, the cost-effectiveness of membrane processes
continuously improves compared to other waste water
treatment processes, since the water and waste water costs
generally rise and the specific membrane prices go down.
With view to possibly increasing requirements for the
waste water treatment technology, the attractiveness of
the membrane bioreactor process (micro- or ultrafiltra-
tion) combined with a downstream nanofiltration or
reverse osmosis installation will grow. Due to the high
attainable sludge age and the downstream membrane
stage, the membrane bioreactor process is also suited for
the removal of some organic trace substances.
Structure and contents of this publication
This publication gives an overview of the present use of
membrane processes in municipal and industrial waste
water treatment, in Germany in particular. Membrane
technology is still being developed and the number of
application possibilities continues to increase.
This publication is intended for both specialists and lay-
men. It is less a comprehensive textbook or manual for
the solution of all problems concerning design, building
and operation of a membrane installation than rather an
instrument, which sensitizes the reader to these ques-
tions and offers solutions. The reference to practice and
the relevance of membrane technology to waste water
treatment becomes clear by the description of installa-
tion examples from the municipal and industrial field in
Germany and outside of Germany. The locations of the
installations described are shown in the following figure.
24
Introduction
25
! municipal plants with microfiltration
! municipal plants with ultrafiltration
industrial plants with microfiltration
industrial plants with ultrafiltration
industrial plants with nanofiltration
Sites of the waste water treatment plants with membrane technology in Germany described in this publi-
cation
industrial plants with reverse osmosis
or the combination UF/RO
industrial plants with the combination
UF/NF
industrial plants with the combination
MF/UF/NF/RO
Introduction
26
The contents of this publication is subdivided into several
partial chapters, each of them representing a complete
unit. Therefore they can be read independently from each
other and allow the reader to orient himself according to
the focus of his interests. The following overview sum-
marizes the contents of the individual chapters and shows
the reader the way through the publication.
Annex: Contacts, possibilities for promotion
Guideline
Chapter 1: Basics
Chapter 2: Municipal waste water treatment
Chapter 3:Industrial waste water treatment
Chapter 4: Instructions and standards
Membrane technology in waste water treatment
Structure and contents of this publication
Basics of Membrane Technology 1
Basics of Membrane Technology1
1.1
Basics of Material Separation by means of
Membrane Technology
Material separation by means of membrane technology is
a physical separation process. Compared with other sepa-
ration technologies, this technology has the advantage
that the separated materials are neither thermally nor
chemically or biologically modified. The fields of applica-
tion of membrane processes stretch from simple filtration
of solids, e. g. separation of activated sludge in municipal
waste water treatment, up to the separation of materials
within the molecular range, e. g. retention of dissolved
salts in seawater desalination.
The operating principle of a membrane can be described
in the wider sense like that of a filter. As shown in Figure
1-1, a substance mixture, called feed or raw solution (e. g.
raw waste water) is separated by the membrane. The part
which passes through the membrane almost unhindered is
called permeate or filtrate. To waste water purification
the permeate represents the treated phase. The portion
retained by the membrane is the brine or concentrate.
The driving force for the separation process is the pres-
sure difference between the feed and permeate side, the
so-called transmembrane pressure difference or
transmembrane pressure. It is applied by overpressure on
the side of the feed or low pressure on the side of the
permeate. Dependent on the membrane employed, the
transmembrane pressure is between 0.1 bar and 70 bar,
in special cases it is up to 120 bar.
The characteristics selectivity and capacity are of deci-
sive importance for the economic efficiency of a mem-
brane process. The selectivity describes the ability of a
membrane to differentiate between the components of a
mixture and thus to separate one phase from the other.
By capacity of a membrane, we understand the flow
under specific operational conditions. The flow is defined
as the volumetric flow rate per unit surface area (unit:
L/(m2 · h)).
28
small particleslarge particles
raw solution,waste water, feed
brine,concentrate
membrane permeate,filtrate
Figure 1-1
Operating principle of micro- and ultrafiltration membranes
Basics of Membrane Technology 1
Another important feature of a membrane is described by
the parameter permeability. It is defined as the quotient
from flow and the accompanying transmembrane pres-
sure (unit: L/(m2· h · bar)). The permeability of a mem-
brane is influenced by the membrane condition and the
filtration characteristics of the waste water (see chapter
1.7). The latter depend on the material composition and
the characteristics of the waste water mixture, e. g. tem-
perature, particle-size distribution and viscosity.
1.2
Membrane Processes in Waste Water Purification
There are various membrane processes which differ in
their molecular separation size and the driving force
which has to be expended. Which process is employed
depends on the waste water composition and the separa-
tion goal.
The separation goal in municipal waste water purification
is above all the separation of the cleaned waste water
from the biomass in order to meet the effluent standards.
In an industrial company, the employment of a mem-
brane process for waste water purification may be fea-
sible, particularly if a useful integration into the produc-
tion process is possible. Besides the treatment of the
waste water, it is also frequently aimed at reusing the per-
meate and possibly the concentrate, so that these can be
recycled into the production process.
In municipal waste water purification, the membrane
processes microfiltration (MF) and ultrafiltration (UF) are
used. For industrial waste water purification, nanofiltra-
tion (NF) and reverse osmosis (RO) are also of impor-
tance. These four processes are therefore described in the
following.
Figure 1-2 indicates the molecular weight and the size of
the materials which can be separated by microfiltration
(MF), ultrafiltration (UF), nanofiltration (NF) and reverse
osmosis (RO).
The size of some waste water constituents and the pore
size of the membranes applied are presented in Figure 1-3.
29
nanofiltration
microfiltration ultrafiltration
reverse osmosis
filtration
aproximate sizelogarithmic scale
molecular weight[g/mol] or [Dalton]no scale
activated sludge flocs
organic acids
100 10 1 0,1 0,01 0,001
200.000 20.000 2001.000.000 10.000100.000500.000
bacteria viruses
diclofenac •
bisphenol A •nonylphenol •
benzo-a-pyren •EDTA •
saccharrose •amoxicilline •
mercury •simazine •
glycine •salt (NaCl) •acetic acid •
phenol •
poliomyelitis virus •
influenza virus •
herpes virus •bacillus subtillis •
escherichia coli •
mumps virus •
Figure 1-2
The different fields of application of membrane processes
polyvalent ion
low-molecular weightorganic substances
monovalent ion
influenza virus
macro-molecular weightorganic substances
activated sludge flocs
escherichia coli
Basics of Membrane Technology1
30
mem
bra
ne
typicalpore size:0,4 µm
ultrafiltrationpore size: 0,005 – 0,1 µm
microfiltrationpore size: 0,1 – 5 µm
mem
bra
ne
typicalpore size:0,04 µm
Figure 1-3
Size of typical waste water constituents and the pore size of membranes applied
Table 1-1 provides an overview of the membrane proces-
ses presented, with driving force and application possibil-
ities. Further details about the individual processes are
given in the following sections 1.2.1 to 1.2.3.
Two mechanisms are essentially responsible for the mass
transfer in membrane processes: transfer by pores and
transfer due to diffusion. In real membranes both trans-
fer modes can occur in parallel; however, the idealized
classification of membranes is as follows:
• pure pore membranes (“porous” membranes) and
• pure solution-diffusion membranes (“dense” mem-
branes)
Separation by pore membranes (MF, UF) is based on a
sieving effect, while differences in solubility and diffusi-
vity are responsible for the selectivity of solution-diffu-
sion membranes (NF, RO) [RAUTENBACH 1997].
The concentration process of a component to be separa-
ted by a membrane is represented in an idealized manner
for a pore membrane and a solution-diffusion membrane
in Figure 1-4. With the pore membrane, the component
to be separated is retained by the membrane due only to
its size. In the course of concentration, a sharp separa-
tion on the membrane surface can be recognized. When
entering into the membrane, the concentration of the
component in the feed drops down to the concentration
in the permeate.
However, with a solution-diffusion membrane a
reduction of the concentration also takes place within
the membrane due to the transportation mechanisms.
Basics of Membrane Technology 1
31
nanofiltrationpore size: 0,001 – 0,01 µm
reverse osmosispore size: 0,0001 – 0,001 µm
mem
bra
ne
typicalpore size:0,004 µm
mem
bra
ne
typicalpore size:0,0004 µm
Microfiltration liquid/solid pressure difference 0,1 – 3 bar separation of solid matter from suspensions
Ultrafiltration liquid/liquid pressure difference 0,5 – 10 bar separation of macromolecular or colloids, disinfection
Nanofiltration liquid/liquid pressure difference 2 – 40 bar separation of dissolved organic molecules and polyvalent inorganic ions
Reverse osmosis liquid/liquid pressure difference 5 – 70 bar separation of organic molecules and of all ions
in special cases up to 120 bar
Table 1-1
Pressure-driven membrane processes in waste water purification
Membrane process Phase separation Driving force Application
permeateside
feedside
wiP
wiF
pore membrane solution-diffusion-membrane
wiF concentration of the waste waterconstituents in the feed
wiP concentration of the waste waterconstituents in the permeate
feedside
wiF
wiP
permeateside
Figure 1-4
Idealized representation of a pore membrane and a solution-diffusion membrane [according to MELIN 1999]
Micro- and Ultrafiltration
Microfiltration (MF) and ultrafiltration (UF) belong to the
pressure-driven membrane processes. Concerning operat-
ing pressure and molecular separation size, they are cate-
gorized between nanofiltration and filtration (e. g. sand
filtration). The separation mechanisms of the Mf and UF
membranes are similar and the fields of application may
strongly overlap (Figure 1-2), so that both are described
in this chapter.
According to the principle of a porous filter, by MF
and UF all those particles that are larger than the mem-
brane pores are retained completely. The particles held
back can develop a covering layer on the membrane sur-
face. This layer then holds back smaller particles which,
without a covering layer, would pass through the mem-
brane (process controlled by the covering layer).
Characteristic features of micro- and ultrafiltration are
summarized in Table 1-2.
In waste water purification, micro- and ultrafiltration are
used for the separation and retention of particulate and
emulsified waste water constituents. Typical applications
include:
Municipal waste water treatment
• separation of activated sludge and water
• disinfection
• pretreatment prior to a reverse osmosis plant
• phosphate removal after precipitation
Industrial waste water treatment
• Waste water recycling and reuse as process water
for different purposes
• Treatment of landfill leachate combined with a
biological stage
• Recovery of water-based paint from spray booth
effluents by concentration
• e. g. in the metal-working industry:
· Prolongation of the service life of electro-dipcoat
bathes
· Concentration of water-oil emulsions
· Recycling of degreasing baths
Basics of Membrane Technology1
32
Table 1-2
Characteristic features of micro- and ultrafiltration
Mikrofiltration (MF) Ultrafiltration (UF)
Operation mode (see Chapter 1.6) cross-flow- and dead-end-operation cross-flow- and dead-end-operation
Operating pressure 0,1 – 3 bar (transmembrane) 0,5 – 10 bar (transmembrane)
Separating mechanism screening controlled by covering layer, if necessary screening controlled by covering layer, if necessary
Molecular separation size solids > 0,1 µm (see figure 1-2) colloids: 20.000 – 200.000 Dalton*,
solids > 0,005 µm (see figure 1-2)
Membrane types predominantly symmetric polymer or ceramic membranes asymmetric polymer composit or ceramic membranes
(see chapter 1.3) (see chapter 1.3)
Module types spiral-wound, hollow-fibre and tube modules, spiral-wound, hollow-fibre and tube modules,
plate or cushion modules plate and cushion modules
* [Dalton], numerically equivalent to the molecular weight (MW) in [g/mol]
MF UF1.2.1
1.2.2 NF
Basics of Membrane Technology 1
33
Nanofiltration
Nanofiltration (NF) is a pressure-driven membrane pro-
cess which is preferentially used for the recycling of
aqueous solutions. Concerning operational pressure and
separation size, nanofiltration is categorized between
reverse osmosis and ultrafiltration. By means of NF mem-
branes, the retention rate for particles with a molecular
mass greater than 200 g/mol is high; this corresponds to
a molecule diameter of approx. 1 nm.
Typical of NF membranes is their ion selectivity. The
retention of a dissolved salt is determined by the valency
of the anion. Therefore most salts with monovalent
anions (e. g. Cl-) can pass through the membrane, where-
as multivalent anions (e. g. SO42-) are retained [RAUTEN-
BACH 1997]. Characteristic features of nanofiltration are
represented in Table 1-3.
Up to now nanofiltration has not been used in municipal
waste water treatment.
Industrial waste water treatment
• Relief of ion exchangers or downstream reverse osmosis
units
• Removal of colour in the waste water of the textile and
the pulp and paper industry
• Demineralization of waste water containing surfactants
In general:
• Retention of multivalent ions (e. g. SO42-, Cd2+, Cr2+),
but permeation of monovalent ions (e. g. Cl-, Na+)
• Retention of organic compounds
• Separation of components with lower and higher mole-
cular weight in aqueous solutions
Table 1-3
Characteristic features of nanofiltration
Nanofiltration
Operating mode (see chapter 1.6) cross-flow-operation
Operating pressure 2 – 40 bar (transmembrane)
Separation mechanism solubility/diffusion/charge (ion selectivity)
Molecular separation size dissolved matter: 200 – 20.000 Dalton* solids > 0.001 µm (see Figure 1-2)
Membrane types asymmetric polymer or composite membrane (see chapter 1.3)
Module types spiral-wound, tube, and cushion modules
* [Dalton], numerically equivalent to the molecular weight (MW) in [g/mol]
Basics of Membrane Technology1
Reverse Osmosis
Reverse osmosis (RO) serves to separate components of a
solution. It is based on a pressure-driven process, the
driving force resulting from the difference of the electro-
chemical potential on both sides of the membrane. The
non-porous RO membranes can retain dissolved material
with a molecular weight of less than 200 g/mol com-
pletely, so that reverse osmosis achieves a higher separa-
tion efficiency than nanofiltration. Since dissolved salts
are retained to a very high extent, RO has a history
as a proven membrane procedure, which is already state
of the art for example in the desalination of sea- and
brackish water. Characteristic features of reverse osmosis
are compiled in Table 1-4.
Reverse osmosis has no importance in municipal waste
water treatment. Fields of application are [RAUTENBACH
1997]:
Industrial waste water treatment
• Concentration of drainage water from mines contain-
ing CaSO4
• Dewatering of flushing water from photo laboratories
for silver recovery
• Treatment of waste water from textile dyeing (cotton
and polyester dyeing)
• Concentration of cellulose washing water
• Recovery of phosphoric acid
• Treatment of waste water from bleacheries
• Treatment of landfill leachate
34
Table 1-4
Characteristic features of reverse osmosis
Reverse Osmosis (RO)
Operating mode (see chapter 1.6) cross-flow-operation
Operating pressure 5 - 70 bar (transmembrane), in special cases up to 120 bar
Separation mechanism solubility/diffusion
Molecular separation size dissolved matter: < 200 Dalton* (see Figure 1-2)
Membrane types asymmetric polymer- or composite membrane (see chapter 1.3)
Modul types spiral-wound, tube, plate, cushion or disc-tube modules
* [Dalton], numerically equivalent to the molecular weight (MW) in [g/mol]
RO1.2.3
Basics of Membrane Technology 1
35
1.3
Membrane Materials, Structure and Classification
Membranes are classified according to different features
(Figure 1-5), which are briefly explained in the following:
• Origin
• Material
• Morphology and structure
• Manufacturing process
Depending on waste water composition and characteris-
tics as well as operational requirements, different ma-
terials are used for membranes. Membrane materials are
organic (e. g. cellulose, polymer membranes) or inorganic
(e. g. ceramic membranes).
1.3.1
Origin and Materials
Membranes can be of biological and synthetic origin and
differ according to structure, functionality and material
transfer. While biological membranes, e. g. cell mem-
branes, are indispensable for human and animal exist-
ence, in waste water purification only synthetic, solid
membranes are used.
membrane
synthetic
solid
inorganic
non-porous
biologicalorigin
liquid
organic
porous porous
material
morphology
Figure 1-5
Classification of membranes [according to RAUTENBACH 1997]
Organic membranes
At present synthetic polymer membranes are used predo-
minantly because it is possible to select a polymer suita-
ble for the specific separation problem from the existing
huge number of synthetic polymers. Moreover, compared
to other materials, polymer membranes are often chea-
per.
For the separation of a constituent, the structural charac-
teristics of the polymers used, like thermal, chemical and
mechanical stability, and the permeability are decisive.
Examples of organic polymer membranes are for example
polysulfone (PS), polyacrylonitrile (PAN), polyethersul-
fone (PES), polypropylene (PP), polyvinylidene fluoride
(PVDF), acetylcellulose, and polyamide (PA) membranes.
Inorganic membranes
In the recent past inorganic membranes have gained
more and more importance. They are used especially if
the employment of polymer membranes is excluded
because of the characteristics of the raw waste water or
if the organic membrane surfaces have to be cleaned
frequently and intensively due to the waste water com-
position.
Inorganic membrane materials are ceramics, aluminum,
high-grade steel, glass and fiber-reinforced carbon, of
which ceramic membranes at present have the greatest
importance in waste water purification. Compared to
organic membranes, the advantages of ceramic mem-
branes are high resistance against heat and chemicals,
with correspondingly a high regeneration capacity, as
well as reduced aging and long service lives. Disadvan-
tages are above all the higher investments due to the
membrane material and more expensive module con-
structions.
1.3.2
Morphology, Structure and Manufacturing
Concerning the morphology of membranes, we distin-
guish between pore mem-branes and solution-diffusion
membranes (see Figure 1-5 and chapter 1.2). Inorganic
membranes are always pore membranes.
The structure of a membrane may be symmetric or
asymmetric. While symmetric membranes have a nearly
homogeneous structure all over the thickness of the
membrane, asymmetric membranes are made up of two
layers.
The layer on the side of the feed (active layer) determines
the separation behaviour of the membrane, while the
porous layer below serves as support. The supporting lay-
er ensures the mechanical stability of the membrane and
hinders the permeate flow only little. The aim of asym-
metric membrane design is to keep the active layer as
thin as possible and, with this, minimize the filtration
resistance of the membrane. With solution-diffusion
membranes it is therefore possible to obtain flows which
are 50 to 100 times higher than with comparable symme-
tric membranes [MELIN 1999].
Today asymmetric organic membranes are usually manu-
factured as phase inversion or composite membranes.
The active layer and supporting layer of the phase inver-
sion membranes are made from the same material.
However, in the case of composite membranes, the active
layer and supporting layer consist of different materials,
so that both layers can be optimized with a view to cus-
tomizing the characteristics required in each case.
Figure 1-6 shows scanning electron micrographs of phase
inversion membranes (a), (b) as well as of a composite
membrane (c). Figure 1-7 and Figure 1-8 represent the
active layer of a polyethylene membrane at different
resolutions.
Basics of Membrane Technology1
36
Basics of Membrane Technology 1
37
Figure 1-7
Top view of the active layer of a polyethylene
membrane (MF/UF) [AGGERVERBAND 2002]
Figure 1-8
Top view of the broken edge of a polyethylene
membrane (MF/UF), the active layer is visible
[AGGERVERBAND 2002]
denitrifica-tion
symmetricmembrane-layer
200 µm
symmetric polymer membrane (MF) [N.N. 2002a]
activelayer
supportinglayer
7 µm
asymmetric composite membrane(RO) [FRIMMEL, GORENFLO 2000]
activelayer
supportinglayer
7 µm
asymmetric polymer phase inversion membrane(UF) [N.N. 2001a]
Figure 1-6
Scanning electron micrographs of cross-sections of
different membranes
Basics of Membrane Technology1
1.4
Membrane Forms and Modules
Depending on the manufacturing process, we distinguish
two basic membrane forms:
• tubular membranes and
• flat membranes
These membranes are arranged in an engineered unit,
the module. Besides the membrane itself, the module is
of decisive importance for the efficiency of a membrane
stage. There are a huge number of different module con-
structions because the modules are adapted in their con-
struction to meet the requirements of the end use.
The basic membrane forms, which depend on the condi-
tions of production, are assigned to the module forms
represented in Figure 1-9. In some special cases this strict
allocation is not permissible, e. g. if some membranes
used in tube modules were manufactured by the tubular
processing of flat membranes. Concerning tubular mem-
branes, we distinguish as module constructions the tube,
capillary and hollow-fibre module. For flat membranes
we distinguish plate, spiral-wound, cushion and disc-tube
modules.
The different module forms can be characterized regard-
ing the arrangement of the separation layer, the compo-
nent density and, with the tubular diaphragms, regarding
the diameter (free flow cross-section) (Table 1-5, Table 1-6).
Due to the different characteristics related to performan-
ce and operation (e. g. operating mode, susceptibility to
blockage, simple backwashing etc.) and the surface-speci-
fic module costs, certain module types are preferentially
used depending on the waste water to be treated. A prere-
quisite for module selection is in each case the selection
of the membrane process and/or the membrane which is
suitable for the separation problem. Table 1-2 (MF and
UF), Table 1-3 (for NF) and Table 1-4 (for RO) can be used
to identify which module types are used in the different
membrane processes.
38
membrane form
module form
tubular flat
tube modul
capillary module
hollow-fibre module
spiral-wound module
cushion module
plate module
disc-tube module
Figure 1-9
Membrane and module forms
Basics of Membrane Technology 1
The following figures present module forms which are
used particularly in industrial waste water treatment.
They are described with the help of pictures and/or flow
sheets. Further examples and explanations concerning
e. g. the plate and capillary modules used in municipal
waste water treatment are given in chapter 2.1.2.
39
Table 1-5
Characteristic values, advantages and disadvantages of module types with tubular membranes
Tubular membranes
Tube module Capillary module Hollow-fibre module
Arrangement of the inside outside/inside outside/inside
separation layer
Inside diameter 5,5 ... 25 mm 0,25 ... 5,5 mm 0,04 ... 0,25 mm
Component density < 80 m2/m3 < 1.000 m2/m3 < 10.000 m2/m3
Operating mode cross-flow dead-end/cross-flow dead-end
Advantages hardly susceptible to blockage high component density extremely high component density
low pressure loss operation controlled cheap production backwashing possible favourable specific membrane costs
by covering layer is possible on the permeate side high pressure resistance
Disadvantages low component density low pressure resistance susceptible to blockage pressure loss
Table 1-6
Characteristic values, advantages and disadvantages of module types with flat membranes
Flat membranes
Plate module Spiral-wound module Cushion module
Arrangement of the outside outside outside
separation layer
Component density 40 ... 100 m2/m3 < 1.000 m2/m3 ca. 400 m2/m3
Operating mode cross-flow dead-end/cross-flow dead-end/cross-flow
Advantages membranes can be changed separately cheap production few seals little pressure losses on the permeate side
hardly susceptible to blockage high component density hardly susceptible to fouling
Disadvantages many seals long flow path on the permeate side low component density
low component density mechanical cleaning not possible many seals
risk of blockages
Basics of Membrane Technology1
Tube modules
Inside a jacket or a pressure tube, several supporting
tubes of smaller diameter which are perforated or perme-
able to the permeate, are combined. The tubular mem-
brane layer is applied on the inside of the tubes. The feed
is pumped through these tubes and is collected in the
outside space between the pressure tube and supporting
tubes and is then withdrawn at a connecting piece on
the pressure tube.
40
permeate collectorpermeate
feed
connectionthread
sealing ringsmembrane-supporting tube
membrane
brine
feed
permeate
Figure 1-10
Tube modules [photo: WEHRLE WERK AG]
Basics of Membrane Technology 1
41
Capillary or hollow-fibre modules
In a pressure tube, a large number of capillary and/or
hollow-fibre membranes are combined into a module.
Comparable to multichannel tube modules, the capilla-
ries and/or fibres can be fed with the feed stream so that
filtration takes place from inside to outside.
In addition there is a construction for which membrane
capillaries/fibres with an outer coating are used. In this
case, filtration takes place from outside to inside and the
permeate is withdrawn on the inside of the capillaries/
fibres.
More capillary module forms are described in chapter 2.1.2.
hollow fibre
feed: inside
permeate
feed: outside
feed
permeate feed
feed permeate
pressure tube bonding (resin)
Figure 1-11
Capillary or hollow-fibre modules [photo: KOCH MEMBRANE SYSTEMS]
Basics of Membrane Technology1
42
Spiral-wound modules
This module consists of one or more membrane bags
which are wound helically with one spacer each (feed
spacer) around the permeate collecting pipe. The mem-
brane bags are closed at three sides and at the open side
the bags are attached to the perforated permeate collec-
tion pipe. The inside of the membrane bags is filled with
a porous plastic textile (permeate spacer), which allows
the permeate to flow between the membranes. The cylin-
dric module resulting from the whirl is supplied to the
front with the feed, which flows through the module in
an axial direction. While the feed flows through the
space outside of the membrane bags resulting from the
feed spacer, the withdrawn permeate flows inside the
membrane bags helically to the permeate collection pipe.
feedspacer
feed flow
central tube
membrane
permeate in thepermeate chanal
permeate spacer
permeate-flow in thecentral tube
Figure 1-12
Spiral-wound modules [schematic drawing: N.N. 2001], [photo: NADIR FILTRATION GMBH]
Basics of Membrane Technology 1
43
Cushion modules
Cushion modules are constructed by analogy to spiral-
wound modules from membrane bags with intermediate
woven fabric fleece. In this case all sides of the bags are
closed and the permeate is withdrawn through one or
more openings, provided with round seals, in the cushion
provided.
As can be seen in the figure, several cushions can be inter-
connected via the permeate openings. The cushion packa-
ges are then inserted into a pressure tube with modular
character. In its wall is the permeate collection pipe with
connections and seals for the corresponding permeate open-
ings of the cushion packages as well as for the following
components of the pressure tube.
permeate-drainage pin
membranecushion stack
permeate channel (permeate discharge)
pressure tube
spherical shell
spacer
raw water
membrane
drainage fleece onpermeate side
support plate
permeatechannel
spacer1 – 3 mm
(variable channel height)
membrane
permeate drainagepin
drainage fleece onpermeate side
Figure 1-13
Cushion module [schematic drawing and photo: ROCHEM UF SYSTEME GMBH]
Basics of Membrane Technology1
44
Disc-tube module (DT module)
The disc-tube module (Figure 1-14) is made of supporting
discs and membrane cushions which are alternately
stacked on a tie rod, so that open flow channels result
between the discs and the membrane cushions on the
side of the raw water. The supporting discs of the DT
module are provided at their outer edge with a sealing
ring which juts out evenly at both sides. An annular gap,
formed by ribs, through which the raw water flows
during operation, a slot for sealing between membrane
cushion and supporting discs, and a lead-through for the
tie rod with permeate discharge slots are arranged centri-
cally. The membrane cushions are made of flat mem-
branes with internal woven fabric fleece and are welded
at the outside.
The preassembled disc-membrane stack is fitted into a
pressure tube. The raw water is fed between the inside
wall of the pressure tube and the sealing rings at the edge
of the discs to the annular gap in the first disc of the
disc-membrane stack and filtered from outside to inside
through the membrane cushions.
The permeate is withdrawn via the round lead-through
in the center of the membrane cushions, the discharge
slots in the supporting discs and a drill-hole in the end
piece of the membrane stack. The open annular gaps and
the flow paths between the membrane cushions and the
discs also allow for the treatment of liquids with higher
colloids or solids loads.
Figure 1-14
Disc-tube module (DT module) [PALL 2001]
Basics of Membrane Technology 1
45
The membrane system from the company inge AG
Another development is the module from the company
inge AG with new, so-called, Multibore capillaries. As
Figure 1-15 shows, these capillaries have seven drillings
each, which have approximately the inside diameter of
conventional single capillaries. Thus, the mechanical
integrity of the membrane capillaries is increased and
capillary breaks occur more rarely than with single capil-
laries.
The Multibore capillaries are operated according to the
inside-outside principle, i. e. supplied from their inside
with the raw water to be filtered. Thus they are applica-
ble only in the case of small solid contents in the raw
water, comparable to the single capillary modules with
inside flow. In the case of capillary membranes with in-
side flow and small feed channel dimensions, higher
solid contents frequently cause blockages. Therefore, the
preferred field of application of the Multibore capillaries
is drinking water processing.
Figure 1-15
New Multibore capillaries from the company inge AG [photo: INGE AG]
Basics of Membrane Technology1
1.5
Arrangement of Modules
A membrane stage is a unit functioning in itself, which
consists of modules, pumps, valves etc. Besides the selec-
tion of a membrane or a membrane module suitable for
the waste water mixture to be separated, the arrangement
and/or connection of the modules is critical to the per-
formance of a membrane stage (Figure 1-16). In waste
water treatment, the volumetric flow to be separated and
the permeate quality or permeate yield to be obtained are
important.
We distinguish two basic connections of modules:
• series connection and
• parallel connection
Series connection is used if the permeate yield from one
module is not sufficient. Several modules are connected
in series, so that according to Figure 1-17, the concentrate
flow of a module serves as feed for the next module and
the permeate of the single modules is brought together.
With parallel connection (Figure 1-18), the feed is dis-
tributed to the individual modules connected in parallel.
The number of modules in parallel connection depends
on required the capacity of the membrane stage. The
modules in parallel connection are called a block. The
waste water-specific permeate yield or the concentration
within a block corresponds to the yield or concentration
that is attained with one module.
While in municipal waste water treatment pure parallel
connection dominates, combinations of both basic con-
nection types are used in industrial waste water treat-
ment in order to achieve the desired purification goal or
the maximum concentration:
46
feed
concentrate
permeate
Figure 1-17
Series connection of modules [according to BAUMGARTEN 1998]
desiredeffluentquality
feed
concentrate
membrane element module modul connection membrane stage
Figure 1-16
From the membrane element to the membrane stage
Basics of Membrane Technology 1
47
• fir tree structure (Figure 1-19)
• feed-and-bleed structure
Figure 1-19 shows an example of the fir tree structure
which is frequently used (e. g. in the seawater desalina-
tion). The modules within blocks one and two are con-
nected in parallel and all three blocks among themselves
in series. With this structure, the concentrate flow is con-
tinuously concentrated or minimized from block to block
and the permeate yield is correspondingly increased. Since
the permeate is withdrawn from each block, the volume-
tric flow to be treated reduces from block to block. There-
fore, the number of modules required in the following
block is reduced so that, e. g. with tube modules, the
overflow conditions are adapted to the requirements also
in the downstream membrane elements.
If the fir tree structure cannot be used because the feed
flow rate is smaller than is necessary for the module ap-
plied, the feed-and-bleed structure or the recircula-
tion cycle is used within each block. With this structure
the feed flow rate is increased by mixing the concentrate
with a part of the feed by internal recirculation. Thus a
higher concentration or higher permeate yield can be
achieved with one module. This is used for example in
landfill leachate treatment.
feed
concentrate
permeate1st block
2nd block
3rd block
Figure 1-19
Arrangement of several modules according to the fir tree structure
[according to RAUTENBACH 1997]
feed concentrate
permeate
Figure 1-18
Parallel connection of modules [according to BAUMGARTEN 1998]
Basics of Membrane Technology1
1.6
Operating Modes
In principle, we distinguish two filtration operating
modes:
• dead-end or static filtration and
• cross-flow or dynamic filtration
Cross-flow operation is used in nanofiltration and reverse
osmosis. In ultra- and microfiltration both operating
modes are possible.
In the cross-flow mode (cross-current filtration) the feed
is pumped parallel to the membrane surface and the per-
meate is withdrawn diagonally to it. In dead-end ope-
ration the membrane is fed orthogonally, comparable to
a “coffee filter”. Figure 1-20 illustrates the differences bet-
ween the two operating modes.
Due to the retention of suspended material, a covering
layer develops on the feed side, which diminishes the fil-
tration capacity. As a result, the permeate flow decreases
with progressive process duration. As preventive measure,
the entire module is submitted in intervals to backwashing.
Figure 1-21 shows the decrease of the permeate flow, VP,
at a constant feed pressure, pF, as set target (left) and the
increase of the feed pressure at a constant permeate flow
as set target (right) over the filtration interval. By remo-
val of the covering layer during the backwashing inter-
val, ideally the original filtration capacity will be reached
again.
In cross-flow operation the formation of a covering layer is
diminished because there is a continuous flow over and
parallel to the membrane. Thus, a state of equilibrium at
the membrane surface between development and remo-
val of the covering layer is achieved by the shear forces.
The overflow is typically generated by pumps. However,
other systems may also be used, such as generating the
overflow by introducing gas below the modules, i. e. by
the ascending gas-feed mixture, or the movement of the
membranes themselves (see chapter 2.1.2). A disadvan-
tage of cross-flow operation compared to dead-end opera-
tion is the higher energy demand as a result of the over-
flow energy which has to be continuously applied.
The term “semi-cross-flow” or “semi-dead-end pro-
cess” is also increasingly used. In this case, process ele-
ments of the two operating modes cross-flow and dead-
end are combined in order to reduce the energy con-
sumption in contrast to the pure cross-flow process. An
example of a semi-cross-flow operation is intermittent
overflow of the membrane according to the cross-flow
principle combined with backwashing intervals so that
the developing covering layer can be removed.
48
Basics of Membrane Technology 1
49
permeate
feed
feed
permeate
cross-flow operation dead-end operation
Figure 1-20
Schematic representation of a membrane in cross-flow- and dead-end filtration [according to MELIN 1999]
time t
filtrationinterval
backwashinginterval
set target :constant feed presure pF
feed
pre
ssur
e p
F
per
mea
te f
low
Vp
time t
filtrationinterval
backwashinginterval
set target :constant permeate flow Vp
feed
pre
ssur
e p
F
per
mea
te f
low
Vp
Figure 1-21
Filtration intervals in dead-end operation [according to RAUTENBACH 1997]
Basics of Membrane Technology1
1.7
Formation of Covering Layers
Municipal and industrial waste waters contain organic
and inorganic matter. During purification of these waste
water by means of a membrane, the constituents of the
feed concentrate and a separation of particles at the
membrane surface occurs due to the selective effect of
the membrane. With increasing operating time, this
results in the development of a covering layer. Covering
layers can be used to a certain extent in a beneficial way
for filtration (e. g. in order to increase the purification
degree), but often they are undesirable because they
diminish the permeate flow and thus the performance of
the membrane.
The reducing performance of the membrane is based on
an increase in the filtration resistance, which increases
the output membrane resistance (Rm) (Figure 1-22).
Concerning the micro- and ultrafiltration membranes,
the increased covering layer resistance results from ad-
sorption (RA), pore blockage (Rp) and the covering layer
formation itself (Rc). However, the increase of the filtra-
tion resistance of the tight nanofiltration and reverse
osmosis membranes is due to a concentration polarisa-
tion (RCP) of dissolved matter, the concentration of which
rises with increasing filtration duration.
Increased resistances due to adsorption (Ra) and pore
blockage (Rp) normally cannot be reduced by measures
such as backwashing or the like, so that during severe
pore blockage another membrane material should be
used. On the other hand covering layer formation can be
decreased or undone by increasing the overflow velocity
or backwashing the membrane with permeate in inter-
vals [PANGLISCH ET AL. 1996].
Measures against covering layer formation and thus for
maintenance of the filtration capacity are treated in the
following chapter.
The formation of covering layers can have different cau-
ses, which also determine the composition of the layer.
We distinguish [BAUMGARTEN 1998]:
• biological fouling (briefly: biofouling)
• colloidal1) fouling
• scaling
Biofouling
Biofilm formation on the membrane surface is caused by
adhesion and the growth of micro-organisms [FLEM-
MING 1995]. Biofouling means that the biofilm causes a
reduction of the performance of the membrane system
by decreasing the specific membrane flow [FLEMMING
2000]. Plant shut-downs should be treated with caution,
since under these conditions the number of bacteria on
the membrane surface may increase dramatically [BAKER
ET AL. 1998].
Colloidal fouling
From the accumulation of colloids results a kind of film
or mucus on the membrane surface, which leads to a
reduction of the filtration capacity.
Scaling
Scaling can be described as coatings on the membrane
formed by inorganic precipitations (crystallization). Usu-
ally they only occur with NF and RO membranes if, for
example, the solubility limit of dissolved salts is exceeded
by excessive concentration on the membrane surface.
Table 1-7 summarizes the substances which can cause the
three types of covering layer presented.
50
1) colloidal = finely spread out, finely dispersed
Basics of Membrane Technology 1
51
permeate sidefeed side
Rp
Ra
Rm
Rc
Rcp
Figure 1-22
Schematic overview of the filtration resistances on the membrane surface and inside the membrane
[KRAMER, KOPPERS 2000]
Table 1-7
Formation of covering layers in membrane filtration [according to BAUMGARTEN 1998]
Scaling (crystallization)
CaSO4
CaF2
BaSO4
SiO2
Mg(OH)2
Covering layer formation
Fouling
Biofouling
• germs
• bacteria growth due to nutrient supply in the feed
• formation of mucus by micro-organisms
Colloidal fouling
• colloidal silicic acid and silicates
• colloidal hydroxides (e. g. Fe and Mn)
• organic colloids (e. g. humic substances, proteins)
Basics of Membrane Technology1
1.8
Measures for Maintenance of the Filtration Capacity
The utilization of membranes in waste water treatment is
practically feasible only if the covering layer formation
(chapter 1.7) is controlled so that safe and economic ope-
ration can be ensured.
The development of covering layers due to fouling or
scaling can be avoided or reduced if the following aspects
Pretreatment measures
In municipal waste water treatment, the pretreatment for
the membrane bioreactor (chapter 2.1.3.2) takes place in
the mechanical stage (e. g. rake, grit chamber, primary
settlement tank). In this stage material which would
disturb the filtration process, such as coarse particles, fats
and fibres, are removed.
Material contents and composition of industrial waste
water vary considerably. The pretreatment measures for a
membrane plant have to be chosen according to the re-
quirements of the waste water composition. Mechanical,
physical, biological and chemical procedures can be used.
Examples are mentioned in Table 1-8.
Optimization of the process configuration
The formation of covering layers is determined essential-
ly by the operating mode – dead-end or cross-flow opera-
tion – and the process control. By operational measures,
such as increasing the backwashing volume or the back-
washing time in dead-end operation, or increasing the
overflow velocity in cross-flow operation, covering layer
formation can be reduced.
However, due to increased energy demand for higher
overflow velocity and because of the permeate loss due
to more frequent backwashing, these measures are not
very economical and can only be optimized during the
operation of a plant.
are considered during construction and operation of the
membrane plant (Table 1-8):
• pretreatment measures
• process configuration
• membrane and module characteristics
• cleaning
52
Table 1-8
Methods for reduction and removal of covering layers
pretreatment
sieve
prefiltration
cooling
neutralisation
preprecipitation
reduction, prevention, removal of covering layers
optimisation of the
process configuration
process design
overflow
flushing method
constructional design
membrane material
structure
module design
module conception
cleaning
cleaning agent
cleaning interval
concentration
Basics of Membrane Technology 1
Structural design
Membrane material and membrane structure have the
largest influence on the formation of covering layers
since the membranes interact directly with the covering
layer forming materials at the inlet. Depending on mate-
rial properties and the charge of a membrane, contami-
nation at the membrane is adsorbed less or more strongly.
The most important structural characteristics regarding
the covering layer formation are the roughness of the
membrane surface, the pore diameter, porosity (share of
the hollow space2)), and the pore size distribution. The
smoother the surface and the smaller the pore diameter,
the smaller the susceptibility to blockage. Also, the ten-
dency for membrane contamination is, in general, smal-
ler with a homogeneous pore distribution [KRAMER,
KOPPERS 2000]. In recent years numerous efforts have
been made to increase the efficiency of membranes by
modification of their characteristics [LINDAU ET AL.
1998; PIERACCI ET AL. 1998; LINDAU, JÖNSSON 1999;
AMANDA ET AL. 2000].
For example, the module configuration determines how
large a pressure increase can be applied to overcome the
filtration resistance caused by the covering layer. This
pressure increase is allowed only within the scope of the
module-specific maximum operating pressure. It must
also be considered in light of the economic operation of
the membrane stage.
Cleaning
If the desired permeate flow is no longer realizable eco-
nomically, a cleaning plan established by the membrane
manufacturer is applied. Restoration or increase of the
53
cleaning
time
flo
w
cleaning interval irreversiblefouling
withcleaning
withoutcleaning
constant pressure
Figure 1-23
Effect of membrane cleaning on the flow at constant pressure
2) Porosity in [%] is defined as the volume of the hollow space in a mem-brane layer compared to the total volume of the membrane layer
Basics of Membrane Technology1
permeate flow is brought about by cleaning with a mem-
brane-compatible cleaning agent. The course of the flow
over time at a constant transmembrane pressure with and
without chemical cleaning is represented in Figure 1-23.
Despite the significant improvement of the flow capacity
by the chemical cleanings, the flow decreases with in-
creasing filtration time. This phenomenon is explained
by irreversible fouling, which cannot be eliminated by
cleaning.
For membrane cleaning, chemical cleaning agents are
used in combination with backwashing (permeate side)
or flushing (feed side). In principle, we distinguish three
types of cleaning:
1. backwashing/flushing of the membrane
2. interim cleaning using chemicals in lower concentra-
tion, e. g. weekly
3. intensive cleaning using chemicals in higher concen-
tration, e. g. biannually
The cleaning agents used for intensive cleaning have a
higher concentration than those used for interim clean-
ing. The cleaning agent is chosen depending on the sub-
stances in the covering layer (Table 1-9).
The effectiveness of cleaning does not only depend on
the cleaning agents applied and their chemical activity,
but is also determined by factors such as temperature, pH
value, contact or reaction time, concentration of the ac-
tive substance, and mechanical forces. The cleaning result
improves with higher temperatures or longer cleaning
times. At higher temperatures the cleaning time can be
reduced, or the temperature can be lower with a longer
cleaning time. In order to adjust the pH value, it is neces-
sary to consider not only the compatibility with the
membrane- or the module material, but also the specific
effectiveness of the cleaning agent in dependence on the
pH.
For handling the cleaning chemicals, the references on
possible hazards of the respective safety data sheets must
be considered. This is of special importance in cases where
the personnel are not familiar (or only to a limited extent)
with the use of hazardous materials, e. g. at waste water
treatment plants.
Moreover it has to be considered that some cleaning che-
micals, after having been used for cleaning, may have
undesirable effects on the permeate quality. After clea-
ning these cleaning solutions have to be collected, if
necessary, and disposed of separately.
54
Table 1-9
Examples of cleaning chemicals and their applications
Covering layer substance
Calcium-, magnesium scaling
Metal hydroxide, inorganic colloids
Organic substances
Bacteria, germs
Cleaning agents applied
Acids, e. g. citric acid, acetic acid
Acids, e. g. citric acid
Anionic surfactants, oxidants, e. g. hypochlorite, hydrogen peroxide,
alkaline cleaning agents, e. g. caustic soda solution
Disinfectants, e. g. hypochlorite; biocides
Basics of Membrane Technology 1
1.9
Other Aspects Concerning the Use of Membrane
Technology in Waste Water Treatment
Molecular separation size and transmembrane
pressure
The choice of a membrane process depends on the waste
water composition and the separation task. In municipal
The driving force or the transmembrane pressure, which
is necessary for the filtration process, has to overcome
the resistance to filtration. It consists of the resistance of
the membrane, the resistance by adsorption and clogging
of the pores in the membrane, the covering layer at the
feed side and concentration polarization [KRAMER 2000].
The transmembrane pressure of immersed membrane
systems in municipal applications is between 0.05 and
0.2 bar in normal operation. The pressure is generated by
pumps installed at the permeate side. If the tanks with
the membranes are arranged above the permeate collec-
ting tank, it is possible to use the difference of the water
levels, i. e. the hydrostatic pressure, as transmembrane
pressure.
Influences on the filtration process and maintenance
of the performance of the filtration operation
In the filtration process, a covering layer is formed by
particles which are retained by the membrane and accu-
mulate on its surface. Thus the resistance to filtration
increases and the permeate flow is reduced, but the filte-
ring effect is normally improved, so that in some cases it
is possible to attain with a micro-filtration membrane the
separation result of an ultrafiltration process.
In many cases, the structure and thickness of the cover-
ing layer is of higher importance for material separation
than the membrane itself. In particular with microfiltra-
tion processes, the formation of a reversible covering lay-
er formation is even wanted, as long as the flow is not
too strongly reduced, because inside membrane clogging
by smaller particles is avoided. It is of importance that a
steady operation results in which covering-layer-forming
and covering-layer removing effects are compensated.
Even with microfiltration membranes, the covering layer
is able to retain, for example, a high percentage of viruses,
which are much smaller compared to bacteria, although
a retention by the membrane pores is not expected
[MELIN, RAUTENBACH 2004]. Since the size of bacteria
is approx. 0.2 µm up to 10 µm and of viruses approx.
0.02 µm up to 0.250 µm, viruses are retained completely
only by ultrafiltration membranes.
waste water treatment, pressure-driven immersed mem-
brane systems with micro- or ultrafiltration membranes
are predominantly used. The pore size of these mem-
branes ensures the retention of solids and of macromole-
cular or colloidal substances up to the size mentioned in
Table 1-10. The separation of smaller particles or substan-
ces with lower molecular weight requires nanofiltration
or reverse osmosis membranes.
55
Microfiltration solids > 0,1 µm 0,1 – 3 bar
Ultrafiltration 200.000 – 20.000 D * 0,5 – 10 bar
Nanofiltration 20.000 – 200 D * 2 – 40 bar
Reverse osmosis < 200 D * 5 – 70 bar
Table 1-10
Molecular separation size and transmembrane pressure of pressure-driven membrane processes
Membrane process Size of the particles, colloids or molecules to be separated Transmembrane pressure
* Dalton, numerically equivalent to the molecular weight in [g/mol]
Basics of Membrane Technology1
Table 1-11 gives an overview of the size of bacteria and
viruses.
To attain stable operation of a membrane installation,
not only coverin-layer-forming and covering-layer-remov-
ing effects have to be compensated, but the development
of fouling must also be limited.
Fouling results from bacteria producing extracellular
polymeric substances (EPS) which mainly consist of poly-
saccharides with incorporated proteins and accumulate
around the cells as mucous capsules. The manifold rea-
sons for the development of these mucous capsules are
not yet completely clarified. Bacteria species producing
mucous EPS are necessary for the development of the
activated sludge floc. By forming a mucous matrix on the
membrane, EPS have a negative effect on the filtration
process. Therefore the process control has to be designed
in such a way that the development of EPS is minimized
as far as possible.
In practice, chemicals are used to counteract the fouling
process. The utilization of an acid, e. g. citric acid, and a
cleaning chemical with oxidative effect, e. g. sodium
hypochlorite or hydrogen dioxide, has proven successful.
To realize chemical cleaning, it is necessary to install a
dosing station for chemicals which is correspondingly
equipped. Cleaning (in situ or on air) can be automated
to a great extent.
Preparation and realization of chemical cleaning require
increased staff employment. For cleaning of the modules
in a separate cleaning chamber, even more staff is needed.
The membrane modules under cleaning are not available
for the filtration process. This has to be considered in the
design of the installation (larger membrane surface area).
According to current knowledge, a precautionary opera-
ting and cleaning strategy, which is adapted to the hy-
draulic load, is technically and economically useful. This
includes planning of a sufficient membrane surface area
and operation of the membranes at moderate transmem-
brane pressure differences.
Within the scope of an optimized operating concept,
buffering of hydraulic peak loads in an upstream balanc-
ing tank may be useful to reduce the membrane surface
area.
56
Table 1-11
Data on the size of viruses and bacteria
Name Length [µm] Width [µm] Diameter [µm]
Bacteria [STARR ET AL. 1981]
Bacteriodes pneumosintes 0,2 < 0,1
Mycoplasma spp. 0,25 0,1
Bacillus subtilis 2,5 0,75
Escherichia coli 2 0,6
Achromatium oxaliferum 100 5
Cristipira pectinis 36 – 72 1,5
Viruses [SCHLEGEL 1976]
Smallpox virus 0,3 0,2
Influenza 0,1
Poliomyelitis 0,02
Basics of Membrane Technology 1
Performance of micro- and ultrafiltration membranes
The model for material transport in micro- and ultrafil-
tration membranes is based on the idealized pore model,
i. e. bigger particles, activated sludge flocs and bacteria,
substances with a molar mass of more than 20,000 g/mol
are not able to pass through the membrane capillaries
because of their size. Dissolved substances such as acetic
acid or urea cannot be retained, unless they are adsorbed
at substances which are retained. By ultrafiltration mem-
branes, substances with a molar mass of at least 20,000
g/mol can be retained.
In municipal waste water treatment, the membrane bio-
reactor process (a combination of activated sludge pro-
cess and membrane process) is used in order to remove
also dissolved, biodegradable constituents. Degradation
of organic matter with development of biomass and con-
version processes such as nitrification and denitrification
take place in the same way as in the conventional acti-
vated sludge process. The substances adsorbed at the acti-
vated sludge flocs are retained safely by micro- or ultrafil-
tration membranes.
Activated sludge flocs consist of colonies of different bac-
teria species. The species pseudomonas, archobacter, ba-
cillus, micrococcus, aerobacter and in particular zoogloea
are found most frequently. Indications on the size of acti-
vated sludge vary, e. g. with diameters of 50 to 200 µm
[HARTMANN 1983] or 5 to 30 µm [KRIEBITZSCH 1999],
i. e. sized which are also retained by microfiltration mem-
branes.
Performance of nanofiltration and reverse osmosis
membranes
To separate organic components from aqueous solutions,
a nanofiltration or reverse osmosis membrane has to be
used. Nanofiltration membranes achieve considerable
retention performances for substances with a molar mass
of 200 g/mol and more, while reverse osmosis membranes
also retain dissolved organic components with a molar
mass of 100 – 150 g/mol nearly completely. Table 1-12
and Figure 1-24 show the molar masses of some selected
waste water constituents.
57
Table 1-12
Molar masses of selected natural organic constituents in domestic waste water [KOPPE, STOZEK 1999]
Name Chemical formula Molar mass [g/mol]
Natural organic constituents
Makropollutants
Acetic acid C2H4O2 60
Citric acid C6H8O7 112
Sucrose C12H22O11 342
Glycine C2H5O2N 75
Urea CH4ON2 60
Mikropollutants
Estradiol C18H24O2 272
Toluol C7H8 92
Synthetic organic constituents
Trichloroethene C2HCL3 132
Dichloro benzene C6H8CL10 435
Sorbic acid C6H8O4 144
Basics of Membrane Technology1
A special feature of nanofiltration membranes is their ion
selectivity. Negatively charged ion groups on or in the
membrane retain dissolved salts with polyvalent anions,
while monovalent anions are able to pass through the
membrane nearly unhindered. In industrial applications
this feature is used to recover valuable material from the
process waste water (e. g. treatment of waste water from
car painting, recovery of dyes in paper mills or in the
textile industry).
For municipal waste water treatment, nanofiltration
membranes open a special perspective for the retention
of organic trace substances.
As resulted from investigations, it is useful to classify the
organic trace substances into three groups with view to
their concentrations in the waste water and their degra-
dation behaviour [MUNLV 2004].
• “Group 1: Substances present in low concentrations
in the waste water” (e. g. Atrazin)
• “Group 2: Substances which are detected in the
inflow and partly in the effluent above the detection
limit and whose concentrations are considerably re-
duced between inflow and effluent“ (e. g. naphtalin,
nonylphenols, bisphenol A)
• “Group 3: Substances which are detected in the
inflow and partly in the effluent above the detection
limit and whose concentrations are not or only slightly
reduced” (e. g. diclofenac)
In Table 1-13 and, some organic trace substances are
selected whose retention can be expected on account of
their molar mass. The real, quantifiable retention perfor-
mance has to be determined by practical tests. At present
intensive studies are realized concerning this subject.
58
reverse osmosis
• glycine• urea• acetic acid
• toluol
nanofiltration
400200 300 500100
molecularweight[g/mol]
• citric acid • trichloroethene • sorbic acid
• estradiol • saccharose • dichloro benzene
Figure 1-24
Molar masses of selected natural organic constituents in domestic waste water
Basics of Membrane Technology 1
59
reverse osmosis
nanofiltration
molecular weight[g/mol]
• clofibric acid • nonylphenol • bisphenol A
• polycyclic aromatic hydrocarbons • TCEP • EDTA • diclofenac • TCPP • trifluralin
200 300 400
• naproxen • carbamazepin
Figure 1-25
Molar masses of selected organic trace substances
Table 1-13
Molar masses of selected organic trace substances [MUNLV 2004]
Name Chemical formula Molar mass [g/mol]
Bisphenol A C15H20O2 228
EDTA C10H16N2O2 292
Trifluralin C13H16F3N3O4 335
Polycyclic aromatic hydrocarbons C22H12 276
Nonylphenol C15H24O 220
Organic trace substances of group 3
Organophosphates
TCEP C6H12O4P1Cl3 285
TCPP C9H18Cl3O4P 327
Pharmaceuticals
Clofibric acid ClC6H4OC(CH3)2CO2H 214
Carbamazepine C15H12N2O 236
Naproxen C14H14O3 230
Diclofenac C14H11Cl2NO2 296
Basics of Membrane Technology1
For operation with high sludge ages, membrane biorec-
tors need considerably smalller activation volumes, com-
pared to conventional plants. It can be assumed that
under these conditions an adaptation of the biomass
takes place which allows increased removal of hardly
removable waste water constituents (cf. e. g. substances of
groups 2 and 3). Complete removal of substances which
possibly are not removed in the membrane biorector
(e. g. substances of group 3) can be attained by direct
downstream arrangement of a nanofiltration stage or a
reverse osmosis. Interconnection of another treatment
stage, as required in conventional activated sludge
plants, is not necessary.
Demands on the operating personnel
A membrane bioreactor differs from a conventional acti-
vated sludge plant with view to operation and process
engineering. At present there is still need for training of
the operating personnel of membrane installations. Con-
cerning the membrane bioreactor process, the Erftver-
band offers a training series at the waste water treatment
plant Nordkanal. In cooperation with MUNLV NRW, the
Aggerverband currently installs a training facility on the
membrane bioreactor process at the site of the waste
water treatment plant Seelscheid.
60
Membrane Technology in Municipal Waste Water Treatment
2
Membrane Technology in Municipal Waste Water Treatment2
Membrane technology has been used for decades in
industrial waste water treatment. In municipal waste
water treatment, however, it has been applied only
for several years.
The main drivers for the recent increased application
of membrane technology in the municipal waste water
treatment market are the new engineering approach con-
cerning membrane modules which are directly immersed
into the activated sludge tank, and further development
of membranes (micro- and ultrafiltration membranes). It
is because of these developments that this technology is
now able to compete with well-established treatment
processes (e. g. the conventional activated sludge process)
and that the purification efficiency has clearly improved.
During the last decades considerable efforts have been
made in the field of waste water treatment, which has
resulted in a significant positive effect on the quality of
water bodies. However, further improvement in water
pollution control has to be realized in the future, specifi-
cally, measures for the removal of germs, bacteria and
viruses from waste water as well as for retention or degra-
dation of micro-pollutants (e. g. substances affecting the
endocrine system or residues from medicaments) must be
addressed.
The following pages provide an overview of the potential
of membrane technology in the municipal waste water
market. The drivers for existing plants to apply membrane
technology will be discussed. The following chapters deal
with these examples as well as with technical and econo-
mic conditions and aspects of planning and operation.
Figure 2-1 serves as guide to the chapter so that the
reader may choose directly the subjects in which he is
interested most.
In the beginning of the chapter the relevant process
engineering is explained in more detail. There exist two
ways of arranging the membrane stage in a municipal
waste water treatment plant (Figure 2-2):
• integration of the membrane stage into the
activated sludge plant, and
• downstream arrangement of the membrane
stage into the effluent of a conventional biological
waste water treatment plant.
In Germany, the integration of the membrane stage
as combination of activated sludge process and membrane
filtration – the socalled membrane bioreactor pro-
cess (chapter 2.1) – is of greatest importance. This pro-
cess is used
• in waste water treatment plants (chapter 2.2), as well as
• in small sewage treatment plants and ship’s sewage
treatment plants (chapter 2.3).
The membrane bioreactor process can be explained as
follows: The membrane stage is used inplace of a secon-
dary clarifier tank to separate the biologically treated
water from the biomass. Depending on the module
system applied, one can distinguish between internal
membrane modules (i. e. fitted into the activated sludge
tank, Figure 2-2, 2a) and external membrane modules
(i. e. installed outside tanks, Figure 2-2, 2b).
Membrane stages arranged downstream of bio-
logical treatment stages (Figure 2-2, 3) are used to obtain
complete retention of solids and farreaching disinfection
of the effluent (see chapter 2.4).
62
Membrane Technology in Municipal Waste Water Treatment 2
63
Figure 2-1
Background – planning – operation of a municipal membrane bioreactor, contents of the chapter
“Membrane technology in municipal waste water treatment“
Procedure
Motive
Target
p. 286
p. 66 ff.
Example
New construction, upgrading, extension of activated sludge stages
Further measures
Information
Concrete examples
Associations
Analysis of theactual situation
p. 286Purification requirements
Local situation
...
Study of variations
p. 286Integration of existing tanks
New construction of tanks
Membrane modules...
p. 70 ffMembrane modules
Economic efficiency
Planning,design,
configuration
p. 82
Design of the membrane bioreactor
Plant configuration
...p. 87 p. 270 ff.
p. 286 f. p. 163Concrete examples
Consulting engineers
Plant manufacturers
Operation
p. 287Cleaning
Energy consumption
Staff
p. 266 ff.
Concrete examples
Plant operators
p. 95 ff.
p. 95 ff.
p. 92 ff.
p. 270 ff.
p. 95 ff.
p. 266 ff.
Consulting engineers
p. 69
p. 64
p. 70 ff.
p. 89 f. p. 89 f.
Membrane Technology in Municipal Waste Water Treatment2
64
Figure 2-2
Conventional waste water treatment according to the activated sludge process and possibilities for the
arrangement of a membrane stage at municipal waste water treatment plants [OHLE 2001]
raw waste water
conventional process engineering in municipal waste water treatment
effluent
if nec. more far-reaching measurese.g.: NN, SF, UV1
RE/SFF VK BB BB NK
2a
2b
3
integration of the membrane stage in municipal waste water treatment
raw waste waterRE/SFF VK BB
effluent
If nec. FS optional
M
RE/SFF VK BB
If nec. FS optional
M
downstream arrangement of the membrane stage in municipal waste water
raw waste waterRE/SFF VK BB BB NK
effluentM
raw waste water effluentBB
RE⁄SFF screen, grit and grease trapVK primary settlement tankFS fine screen
BB activated sludge tankNK 2nd settlement tankSF sand filter
M membrane stageUV UV treatmentNN post-nitrification stage
Membrane Technology in Municipal Waste Water Treatment 2
With view to water pollution control, membrane techno-
logy represents a future-oriented solution. Thanks to the
high attainable sludge age and another downstream
membrane stage (nanofiltration or reverse osmosis), the
elimination of organic trace substances can also be
expected. Figure 2-3 shows such a process combination.
65
raw water inflow
rakefine screen(optional)
grit and grease
trap
denitrificationstage
nitrificationstage
membrane Stage I(MF/UF)
membrane stage II(NF/UO)
outflow
optionalprocess
supplement
excess sludge
recirculation
Figure 2-3
Flow sheet of a waste water treatment plant with membrane bioreactor process and downstream
membrane stage
Membrane Technology in Municipal Waste Water Treatment2
2.1
The Membrane Bioreactor Process
2.1.1
Description of the Process and Fields of Application
The membrane bioreactor process is a combination of
biological waste water treatment according to the activa-
ted sludge process and the separation of the sludge-water
mixture by membrane filtration. Waste water treatment
in the true sense takes place by metabolic and conversion
processes in the biological stage (activated sludge pro-
cess). Simplifying we can say that the carbon and nitro-
gen compounds present in dissolved form in the waste
water are converted to CO2 and N2 and integrated into
the biomass. This task is done by micro-organisms which
are found as suspended sludge flocs in the activated sludge
tank.
To separate the treated waste water from the suspended
biomass, membrane stages with pressure-driven micro-
or ultrafiltration membranes are used. The membranes
ensure a complete retention of solids and biomass, so
that a secondary settling tank for phase separation down-
stream of the activated sludge tank is not necessary. The
result is a treated waste water which is free of solids and,
to a far-reaching extent, disinfected. Therefore the em-
ployment of a membrane stage in municipal waste water
treatment is particularly interesting if higher demands on
the quality of the treated waste water are made.
For the membrane bioreactor process, one distinguishes
between internal and external arrangement of the mem-
brane modules. Internal arrangement means that the
membrane modules (Figure 2-2, 2a) are immersed within
the bioreactors into the mixed liquor (immersed system).
With external arrangement the mixed liquor is with-
drawn from the bioreactors and the membrane modules,
usually tubular modules, are fed in cross-flow operation
(Figure 2-2, 2b). For financial reasons only immersed
membrane systems are used in municipal waste water treat-
ment (chapter 2.1.2).
Since the efficiency of phase separation by the membrane
bioreactor process is to a great extent independent of the
settling characteristics of the mixed liquor, the aeration
stage can be operated at much higher biomass concentra-
tion than in conventional plants. With the latter, bio-
mass concentrations of MLSS < 5 g/l are typical, while the
membrane bioreactors working at present are operated at
MLSS concentrations of 9 – 16 g/l. Thus it is possible to
reduce the aeration tank volumes at equal sludge loading
by up to 75 % compared to conventional plants.
Table 2-1 summarizes the main advantages of the use of
the membrane bioreactor process in municipal waste
water treatment.
Considering the aspects mentioned in Table 2-1, today
the membrane bioreactor process proves to be, from the
economic point of view, an advantageous option com-
pared to other process techniques, under the following
general conditions:
66
• complete retention of solid matter:
- improved effluent quality concerning the parameters COD and BOD5
- far-reaching disinfection of the effluent, i. e. secondary settling, filtra-
tion and disinfection plant are replaced
- no influence on the effluent quality by floating or bulking sludge nor
scum formation (possibly lower demand for auxiliary agents)
• smaller aeration tank volumes due to higher biomass concentration
• existing plant components can be used for plant expansions
• less space required for the waste water treatment plant
• expansion of plants by addition of modules
Table 2-1
Advantages of the membrane bioreactor process
compared to the conventional activated sludge
process
Advantages
Membrane Technology in Municipal Waste Water Treatment 2
Demands on the effluent quality
If higher demands are made on the discharge parameters
(standard monitoring or hygienic parameters) (e. g. for
the discharge into “weak“ receiving waters, drinking
water protection areas or bathing water), membrane bio-
Studies on the hygienic quality of the effluent have shown
that by using membrane bioreactors it is possible to com-
ply with the standards of the EU Directive on Bathing
Waters without further treatment measures. To illustrate
the high effluent quality of membrane bioreactors,
the germ load of a conventional waste water treatment
plant [BAUMGARTEN, BRANDS 2002] is compared in
Figure 2-4 to that of the Büchel pilot plant (in each case
mean values from multiple sampling). Concerning the
hygienic effluent parameters, it is evident that the mem-
brane plant is superior to conventional plants.
reactors represent an economically interesting solution.
As shown by Table 2-2, the effluent quality is clearly better
than that of conventional waste water treatment plants.
67
Solids (filterable solids) mg/L 10 – 15 0
COD mg/L 40 – 50 < 30
Ntot mg/L < 13 < 13
Ptot (with simultaneous precipitation) mg/L 0.8 – 1.0 < 0.3
Microbiological quality hygienically alarming bathing water quality
Dry matter content in the g/L < 5 < 20
activated sludge tank
Specific energy consumption kWh/m3 0.2 – 0.4 0.7 – 1.5
Table 2-2
Performance data of membrane bioreactor plants compared to conventional activated sludge plants
[DOHMANN ET AL. 2002]
Parameter Conventional Membrane bioreactor
activated sludge plant
Membrane Technology in Municipal Waste Water Treatment2
Sewer system
If the catchment area is mainly drained by a separate
sewer system, the membrane surface area to be installed
into the aeration stage of the waste water treatment plant
is much smaller than in plants where waste water from
combined systems is treated. Thanks to lower hydraulic
fluctuations, the membrane stage is optimally used and
thus is competitive with alternative technical methods for
waste water treatment, even if no higher demands on the
effluent quality are made.
However, an increase in sewer infiltration water requires
more membrane surface area. Therefore, membrane pro-
cesses should be used preferentially in applications with
low amounts of sewer infiltration water compared to the
waste water volume.
Local situation
Due to higher biomass concentrations in membrane bio-
reactors, it is possible to reduce the aeration tank vol-
umes by 50 to 75 % compared to conventional plants. If
the surface area available requires compact construction,
a membrane bioreactor may represent suitable technical
solution. This is shown in Figure 2-5 by way of example
for the comparison of variations for the new construc-
tion of the Kaarst waste water treatment plant.
68
1.000.000
100.000
10.000
1.000
100
10
1E. coli
[MPN/100 ml]salmonellae
[MPN/100 ml]faecal streptococci
[MPN/100 ml]total coliforms[MPN/100 ml]
coliphagae[PFU/l]
total number of germs[colony-forming unit]
conventional WWTP membrane bioreactor EU guide value EU limit value
Figure 2-4
Comparison of the germ load in the effluent of waste water treatment plants
[BAUMGARTEN, BRANDS 2002]
Membrane Technology in Municipal Waste Water Treatment 2
Rebuilding or expansion of installations
Existing installations which have to be rebuilt or expanded
(e. g. because of higher demands on the effluent quality or
increased waste water volumes) can be readily converted
to membrane bioreactors. The membrane stage can be
integrated at low cost into existing components of the
plant, so that demolition or new construction of aeration
tanks is not necessary. This is especially advantageous if
an expansion of the surface of the plant to be upgraded is
not possible due to the local situation.
Since in future the costs for installed membrane surfaces
will decrease (chapter 2.1.4), it can be expected that the
economic efficiency of the membrane process will further
increase. The decision of the water boards (Aggerverband,
Erftverband, Kommunale Wasserwerke Leipzig (KWL)),
which have already gained experience with large-scale
application of membrane technology, to include membrane
technology in their efficiency calculations for new pro-
jects or even to give it priority in planning, clearly indica-
tes its competitiveness compared to conventional techno-
logy. According to KWL, even a change towards mem-
brane technology is expected which will not come out on
top because of enhanced purification requirements, but
only because of economic aspects – taking into account
further reductions of the membrane costs as well as pro-
cess optimizations [WALTHER 2001].
69
Figure 2-5
Schematic representation of the space requirements of a conventional activated sludge plant (edged in
blue) and of a membrane bioreactor (edged in red), example: Nordkanal waste water treatment plant
[ERFTVERBAND 2002]
Membrane Technology in Municipal Waste Water Treatment2
2.1.2
Membrane Modules
For a long time it has been known that membranes are
able to separate activated sludge from water. However,
during only the last ten years, module systems have been
developed which are a relevant process variation, com-
pared to sedimentation, in municipal waste water treat-
ment because of low capital and operating costs.
Until now the so-called low pressure processes using
immersed modules have been the most widespread. Micro-
or ultrafiltration modules are immersed directly into the
mixed liquor and withdraw the biologically treated water
as filtrate at transmembrane pressures of < 0,5 bar in low-
pressure or submergence operation (“gravity flow“). At
present, capillary modules from the company ZENON
and plate modules from the company Kubota have a high
share in the modules being used worldwide on an indus-
trial scale. These modules as well as the latest national
and international developments are presented in the fol-
lowing sections.
Capillary module from the company ZENON, Canada
The hollow fibre module presented in Figure 2-6 (product
name: ZeeWeed®) consists of hundreds of tubular mem-
branes with a diameter of 3 mm oriented vertically be-
tween two plastic blocks (top and bottom header). The
capillary tubes (pore size ~ 0.04 µm) are charged from
the outside with the mixed liquor; the permeate flows
into the interior of the capillary tubes and is discharged
by a collecting channel integrated into the top header.
To minimize the formation of a covering layer, coarse to
medium bubble air is introduced at the bottom header
which generates an up-flow movement of the mixed
liquor and causes the capillary tubes to move between
the headers. Additional covering layer removal is possible
by cyclic backwash of the modules at the filtrate side in
the so-called backpulse mode. Filtration of six minutes
and a backwash time of 30 seconds is a common operat-
ing mode.
70
top header with integratedpermeate collecting channel
membranebundle
rising mixed liquor
support frame with integratedair tube
bottom header
blower
permeate channel
permeatedischarge
supporting layer
membrane
support frame
backwash
air intake
Figure 2-6
ZeeWeed®-module from the company ZENON ,
left: schematic presentation from the operating principle of a module [OHLE 2001],
right: photo of the technical realization as module cassette [photo: ZENON]
Membrane Technology in Municipal Waste Water Treatment 2
During the last years, the module configuration from the
company ZENON has been continuously optimized. A
rather compact configuration has been obtained with the
current capillary module, ZW 500 d (Figure 2-6). The
module cassette presented in Figure 2-7, ZW 1000 (pore
size of the membranes: 0.02 µm), had been designed ori-
ginally for drinking water treatment, but is also used e. g.
for tertiary treatment or for the treatment of the effluent
of a final clarifier or a sand filtration unit.
Plate module from the company Kubota, Japan
The plate modules (Figure 2-8) consist of a support plate
on which the membrane sheet (pore size: ~ 0.4 µm) is
welded at both sides. A drainage and backing fleece is
fixed between the plate and the membrane. The support
plate is provided with drainage channels which come
together in a suction branch for permeate withdrawal.
The individual plates are combined vertically with a
distance of 6 mm parallel to each other to create a plate
package that is fitted into a support frame (Figure 2-8).
The sides of the support frame are closed. The support
frame is installed in an up-flow channel, at the bottom
71
membrane-package
drainage fleece
membrane
suspension
filtratefiltrate collectingchannel
up-flow-channel
pressureaerator
air
suction branch
collecting channels
membranesupport
Figure 2-8
Plate module from the company Kubota,
left: schematic presentation of the operating principle [according to KRAFT, MENDE 1997],
right: photo of the technical arrangement of the plate modules as plate package [photo: KUBOTA]
Figure 2-7
Arrangement of several ZeeWeed®-modules
ZW 1000 in a cassette [photo: ZENON 2004]
Membrane Technology in Municipal Waste Water Treatment2
of which is arranged a device for exhaustive pressure
aeration. Due to the injected air, the mixture of sludge,
water and air rises and flows over the membrane, en-
suring removal of the covering layer. The filtrate is dis-
charged by low pressure at the filtrate side or by the
hydrostatic pressure of the active water head (“gravity
flow") via the filtrate collecting channel which is connec-
ted with the suction branches of each plate. The covering
layer on the plate is not removed by backwashing on the
permeate side. Filtration is instead interrupted in inter-
vals while the modules are continuously aerated [KRAFT,
MENDE 1997]. The break interval for expansion of the
membranes and removal of the covering layer varies ac-
cording to the waste water composition. In some munici-
pal installations, filtration of nine minutes followed by a
break of one minute has proven to be efficient.
As a further development of the combination of up-flow
channel and plate package design, the so-called double-
decker is now offered for large-scale applications (Figure
2-9). Two plate packages are arranged on top of each
other, so that the air introduced, i. e. the activated sludge
mixture, can be used twice. Therefore the energy demand
for module aeration is considerably reduced
Module system from the company PURON AG
A new immersed module system consisting of capillary
membranes with a pore size of 0.1 µm was developed
about five years ago at the RWTH Aachen University and
is now available for application in water and waste water
treatment. Production and marketing of the new mem-
brane filters are realized by the company PURON which
belongs to the KOCH-GLITSCH group.
The patented basic idea of the PURON module is confi-
guring membrane fibres as bundles which are only fixed
at the bottom, while their closed top ends move freely in
the mixed liquor to be filtered (Figure 2-10).
In the centre of each fibre bundle of a module, a nozzle
is arranged to introduce air for movement and cleaning
of the membranes. The air flows up through the mem-
brane fibre bundle from the inside to the outside. Mem-
72
membrane package at the top
membrane package at the bottom
aeration device
Figure 2-9
Basic schematic of the plate module “double-decker“ from the company Kubota [AGGERWASSER GMBH 2004]
Membrane Technology in Municipal Waste Water Treatment 2
brane coatings or fouling material are discharged from
the module. Hair and fibrous compounds are also slipped
off to the top, which helps to prevent the problem of
their accumulation and sticking to the membrane even
with relatively coarse prescreening. Due to defined air
intake, the aeration time of the modules is reduced to
5 – 10 % of the filtration time, and thus the energy de-
mand for overflow is reduced.
In the technical module of PURON a multitude of these
module components are arranged in parallel. The total
membrane surface area of the PURON module is 504 m2.
The fittings and connections of the module are designed
to be compatible with existing module systems.
Pilot tests have been run since August 2001 at the Aachen-
Eilendorf waste water treatment plant within the scope
of a field study on membrane bioreactors promoted by
“Kompetenznetzwerk Wasser NRW“ (competence net-
work water North-Rhine Westphalia). This pilot study
allows individual components of the membrane module
to be operated under real conditions, i. e. with changing
loads. The experiences from this first pilot study were the
basis for the construction of a technical installation at
the Simmerath waste water treatment plant for 750 PE in
NRW. This technical installation has been operating since
the end of 2002 within the scope of a research and devel-
opment project.
73
filtrate
membrane fibres
filtrate
air
fibre holder
module row
air conduit
filtrate
air bubbles membrane fibre
PURON-module module component
• central air intake• single-sided fixation of membranes• assembly from single membrane bundles
Figure 2-10
PURON module and module component [photo: PURON AG]
Membrane Technology in Municipal Waste Water Treatment2
Module system from Martin Systems AG
The Martin Systems AG markets a new module system
called siClaro®. According to information from the manu-
facturer, the innovations of this system are the structure
of the filter and the operating mode of the system.
For the modules, flat membranes with a pore width of
35 nm are used. Each membrane is welded on a support-
ing scaffold with an open grate structure. A drainage
fleece is not necessary. The supporting scaffolds with the
spacers necessary for effective cleaning of the membrane
surface are welded to module blocks. Filtrate collectors
are welded on top and bottom of each module block
transversally to the supporting scaffold. Thanks to this
self-supporting construction, the material thickness of
the supporting scaffold is rather small. This allows for a
large number of variations in combining the module
blocks to a connectable module package. For technical
application, several module blocks are connected side by
side and on top of each other. For example, one siClaro®
membrane module of the type FM 643 ready for connec-
tion (see Figure 2-11, right) consists of 12 module blocks
with a total membrane surface area of 72 m2.
By using fine-bubble membrane tube aerators below the
module package, higher oxygen input is attained. Thus
the air input which is additionally necessary to supply
the micro-organisms is reduced. Backwashing with filtrate
is not necessary because the membranes are fixed trans-
versally to the cleaning water-air mixture.
Figure 2-11 shows a scheme of the module (left) and a
module package (right).
74
Figure 2-11
Membrane module from Martin Systems AG, left: schematic representation of a module block,
right: connectable module package [photo: MARTIN SYSTEMS AG]
Membrane Technology in Municipal Waste Water Treatment 2
VRM® process with rotation plate modules and VUM
process from Huber AG, Germany
The VacuumRotationMembrane system (Huber VRM®
process) has been used since 2001 already on an industri-
al scale at the Knautnaundorf, Saxony, waste water treat-
ment plant. The modules (pore size ~ 0.04 µm) consist of
plate segments (plate packages) arranged in parallel, each
of which is provided with a connection to draw off the
permeate (Figure 2-12). The structure of the plate seg-
ments is similar to that of the Kubota plates. The plate
packages are arranged around a rotating hollow shaft and
are connected by permeate collecting pipes by which the
permeate is withdrawn continuously at low pressure.
In the centre of the plate package, air is continuously
introduced radially and rises between the plates. Due to
the rotation of the plate package, the complete mem-
brane surface is overflown by the rising activated sludge
mixture, so that the covering layer is removed.
Huber AG markets the vacuum upstream membrane®
process (VUM® process) (Figure 2-13) primarily for small
and decentralized waste water treatment plants. In this
process, small plate modules with a membrane surface
area of few square metres are used. The individual filter
plates in the module are covered with ultrafiltration
membranes and arranged in parallel. The VUM® mod-
ules are submerged into the liquid to be filtered, and the
filtrate is drawn off directly across the flat membranes
with a pore size of 0.04 µm. The mixed liquor is generated
in a flush box below the module. It flows diagonally to
the filtration flow direction in order to remove the cover-
ing layers from the filtering surfaces. The modules can be
stacked and combined as a module package so that com-
pact filtration units can be easily adapted to each indivi-
dual case.
75
Figure 2-12
Huber VRM® process [photos: HANS HUBER AG, MARTIN SYSTEMS AG], left: view of a filtration unit,
right: filtration unit installed at the Knautnaundorf waste water treatment plant
Membrane Technology in Municipal Waste Water Treatment2
76
Figure 2-13
Huber VUM® process [HANS HUBER AG], left: view of a module package in two-storey arrangement,
right: view of a module
Figure 2-14
Membrane element and membrane module from the company Mitsubishi [photo: ENVICARE®]
Membrane Technology in Municipal Waste Water Treatment 2
Module system from Mitsubishi AG
Mitsubishi, known among other things for its car produc-
tion, also produces membranes for the filtration of water
and waste water and distributes them packaged in a
module under the designation Sterapore-SUN® (see Figure
2-14). The hollow-fibre membranes are made from poly-
ethylene with a pore size of 0.4 µm. They are fixed hori-
zontally between the permeate-collecting channels and
immersed into the activated sludge. Thus, the hollow
fibres are arranged perpendicular to the up-flow sense of
the activated sludge mixture. In practical operation the
membrane surface is kept free of fouling matter as far as
possible by an air flow which is constantly introduced. In
addition, periodic backwashing of the membranes with
permeate is provided. Up to three membrane modules can
be arranged on top of each other, the relative air require-
ments being lower for three modules than for two.
Membrane system from the company A3 Abfall-
Abwasser-Anlagentechnik GmbH
Another membrane development from NRW is from the
company A3 Abfall-Abwasser-Anlagentechnik GmbH/
Hese Umwelt GmbH. The system is based on the principle
of plate membranes (pore size ~ 0,4 µm) which can be
produced at rather low costs by choosing special material
and employing sophisticated construction principle.
Figure 2-15 shows the view of a prototype and a con-
struction example. Due to a new configuration of the
membrane plate, the membranes developed by the com-
pany A3, unlike the Kubota plate membranes, can be
backwashed on the permeate side. Experience with the
use of the membrane material has been acquired for
several years in the following fields:
• filtration of compost leachate
• filtration of liquid manure
• filtration of fermentation residues from biogas installations
• filtration of activated sludge from textile waste water
treatment plants
• filtration of activated sludge from municipal waste
water treatment plants
77
Figure 2-15
Plate module from the company A3 GmbH [photo: A3 GMBH],
left: photo of the one-storey construction, right: top view of a plate module
Membrane Technology in Municipal Waste Water Treatment2
Module system from US Filter Corporation
The company US Filter produces and distributes an
immersed membrane system with the product name
MemJetTM that is comparable to the systems from the
companies ZENON and PURON. The membrane modules
consist of bundled capillary membranes (pore size ~
0.2 µm) which are fixed at both ends (Figure 2-16). A
mixture of air and activated sludge is introduced by a
two-phase nozzle at the bottom of the module. Accor-
ding to information from the manufacturer, this arrange-
ment is especially designed to efficiently control the
reversible covering layer and to ensure good intermixing
in the membrane reactor so that deposits and fouling on
the membranes are counteracted. The permeate is with-
drawn at the top header of the module. Figure 2-16
shows a schematic presentation and a photo of the mem-
brane module.
Membrane system from Keppel Seghers Belgium
The membrane system produced and distributed by
Seghers Keppel under the product name Unibrane® is
comparable in form to that of the company Kubota.
The membrane module consists of plate membranes
with a nominal pore size of 0,1 µm manufactured by
the company Toray.
The modules can be installed as one- or two-storey con-
struction, adapted to the conditions of the respective
application. Figure 2-17 shows a top view of the modules
submerged in clear water.
78
Figure 2-16
Membrane module from US Filter Corporation
[photo: US FILTER CORPORATION 2004]
permeate
air
mixedliquor
Figure 2-17
Membrane module from the Keppel Seghers
Belgium [photo: KEPPEL SEGHERS BELGIUM NV]
Membrane Technology in Municipal Waste Water Treatment 2
Membrane system of Weise Water Systems
GmbH & Co. KG
The MicroClear filter module consists of immersed ultra-
filtration modules in which membranes with a pore
size of 0.05 µm are fitted. According to the concrete
application, the module consists of 26 – 40 single filter
plates (see Figure 2-18) arranged in parallel. The filter
plates are available with varying space, depending on the
raw water quality. Coarse to medium bubble air is intro-
duced periodically into the modules according to the
needs, so that the activated sludge mixture flows up.
Thus shear forces occur at the membrane surface which
help to control the reversible covering layer. To remove
the covering layer, filtration is interrupted in intervals
while the modules are continued to be aerated. The raw
water is filtered from outside to inside via the membranes
and the permeate is discharged using a vacuum at the
front side of the module by a collecting tube. Depending
on the necessary capacity, between 1 and 100 MicroClear
filters can be stacked in a frame on top of each other or
side by side (Figure 2-18).
79
Figure 2-18
Membrane system from Weise Water Systems GmbH & Co. KG [WEISE WATER SYSTEMS GMBH & CO. KG],
left: structure of a filter element, right: filter system in two-storey arrangement
spacer
filter plate
membrane
filtrate outlets
The aeration device consists of tube aerators provided
with slots.
To control the covering layer, the membrane modules are
aerated during the filtration of activated sludge from the
bottom with coarse-bubble air. As special advantages of
the ceramic membranes, the manufacturer expects high
thermal and chemical resistance as well as long service
life, thus a broader range of application.
Module system from Fraunhofer IGB, Stuttgart
The rotation disc filter from Fraunhofer Institut für Grenz-
Membrane Technology in Municipal Waste Water Treatment2
New membrane module developments in Germany
Module system from ItN Nanovation
The membrane system from the company ItN Nanova-
tion consists of immersed modules mounted from cera-
mic plate membranes (Figure 2-19). According to the
manufacturer, the membrane material is �-Al2O3 for the
supporting layer and �-Al2O3, TiO2 or ZrO2 for the active
separating layer. The membranes are available with dif-
ferent molecular separation sizes in the fields of micro-
and ultrafiltration.
One module comprises 86 membrane plates with a spac-
ing of 7 mm between the plates. The active membrane
surface area of a module is approx. 11 m2. Eight modules
can be combined maximally to a rack.
80
Figure 2-19
Ceramic plate membranes from the company ItN
Nanovation [photo: ItN NANOVATION]
Figure 2-20
Membrane module and configuration of the modules in the rack with underlying aeration device
[photos: ItN NANOVATION]
Membrane Technology in Municipal Waste Water Treatment 2
flächen- und Bioverfahrenstechnik (IGB) (Fraunhofer
Institute for Interface and Bioprocess Technology) con-
sists of a cylindric case in which a membrane disc stack is
fitted on a rotating hollow shaft (Figure 2-21). The rota-
tional speed varies between 200 and 500 revolutions per
minute, according to the type and the concentration of
the waste water constituents. The rotation disc filter can
be arranged dry or operated as immersed system.
The membranes are made from a ceramic material
and can achieve relatively high permeate flows. At pres-
ent ceramic discs with an outside diameter of 152 or
312 mm and in six molecular weight separation sizes are
commercially available. Figure 2-22 shows a dry-arranged
lab-scale module with pressure casing.
In immersed arrangement, the rotation disc filter is used
without the pressure casing. The permeate passes the
separating layer on the membrane disc from outside to
inside and is withdrawn by the hollow shaft. The cover-
ing layer is controlled by centrifugal force that causes the
laminar boundary layer sticking to the filtering disc to
flow radially to the outside. The result is continuous
renewal of the covering layer.
81
rotating hollow shaft
membrane filter discs
cylindric casing
inflow
solid outlet
filtrate
Figure 2-21
Basic layout sketch of the rotation disc filter
Figure 2-22
Modules of the rotation disc filter in laboratory
scale [photo: FRAUNHOFER IGB]
Membrane Technology in Municipal Waste Water Treatment2
The results from pilot plant operation have shown that
the rotation disc filter is insensitive to clogging and accu-
mulation and sticking of fibrous material which reduce
the performance of membranes. Therefore, it is also sui-
ted for the filtration of digested waste water sludge diges-
tion. At present a demonstration plant for filtration of
waste water sludge is operated at the Heidelberg waste
water treatment plant. In 2005, a large-scale installation
for sludge filtration will be built at the Tauberbischofs-
heim waste water treatment plant. At both plants, cera-
mic membranes with a pore size of 0.2 µm are used.
Other module systems for the separation of
activated sludge and water
Besides the module systems described in the previous sec-
tions, there are others that, like some of those mentioned
above, are not yet applied on a large scale in municipal
waste water treatment in Germany. However, some
manufacturers have references in Europe, America, and
Asia (e. g. the modules for immersed systems from the
companies Rhodia and Norit). For several years the num-
ber of manufacturers and new module developments has
been steadily increasing.
2.1.3
Planning and Operation of Membrane Bioreactors
The “new” membrane filtration process has important
design-specific, constructive and operational differences
compared to conventional waste water treatment. The
most important aspects are summarized in this section.
They are based on the findings from the first years’ of
operation of large-scale installations, a large number of
lab-scale and semi-technical studies, including findings
from The Netherlands (field test Beverwijk) [V.D. ROEST
ET AL. 2002], and the publications of the ATV-DVWK
committee of experts KA 7 – Membrane Bioreactor Pro-
cesses [ATV-DVWK 2000a, DWA 2005].
This committee with representatives of operators, manu-
facturers and scientists, elaborates a standard for mem-
brane bioreactors analogous to with the standard ATV-
DVWK-A 131, so that a binding regulation can be expect-
ed after some years. In anticipation of this standard, the
deviations from design, planning and operation of con-
ventional activated sludge stages are focused on in this
section. The following items are discursed:
• pretreatment of the raw waste water (mechanical waste
water treatment)
• process design and calculation of the biological and
membrane filtration stages (reactor volume and mem-
brane surface area)
• design of the aeration equipment
• design of sludge treatment
• operation of the membrane stage including membrane
cleaning and
• variations in boundary conditions and safety in the
case of disturbances
2.1.3.1
Design
The design of a membrane bioreactor can be realized
according to the design principles for conventional acti-
vated sludge stages, i. e. to the standard ATV-DVWK-A 131
[ATV-DVWK 2000c] or to the approach of the University
Group [DOHMANN ET AL. 1993]. In addition, the Insti-
tute for Environmental Engineering of the RWTH Aachen
University will author in the first half of the year 2005
an upgrade of the design tool “ARA-BER”, whose devel-
opment is financed by the Land North-Rhine Westphalia.
In conventional design, an iterative process is used to
design the volumes of activated sludge tanks and secon-
dary settlement tanks because of the interactions bet-
ween both process steps. This is not necessary in the case
of membrane bioreactors. Under the boundary condi-
tions listed in the following sections it is possible to
design the membrane stage and the activated sludge
tanks to a great extent independent from each other.
Chapter 2.5 contains an example for the design of a
membrane bioreactor based on the following recommen-
dations.
82
Membrane Technology in Municipal Waste Water Treatment 2
For sludge ages < 30 days, the activated sludge tanks
are designed according to the proven design method of
ATV or the University Group approach mentioned above.
For higher sludge ages, the recommendations of the ATV-
DVWK committee of experts KA 7 “Membrane Bioreac-
In Germany, up to now all existing and planned large-
scale membrane bioreactors for municipal waste water
treatment are designed for sludge loadings of BTS,BOD5
� 0,08 kg BOD5/kg ,TS·d. This design value is chosen to
achieve nitrogen removal at simultaneous aerobic sludge
stabilization (sludge age > = 25 d).
In the design of activated sludge tanks, the total solids
content (TSBB) and the sludge volume index (SVI) in the
activated sludge stage are considered in dimensioning
the volumes of the activated sludge and secondary settle-
ment tanks. For membrane bioreactors this is not the
case. In principle, the TSBB can be independently chosen
to determine the volume of the activated sludge tank.
However, in practice TSBB design values in the range of
10 – 15 g/l have proven to be well-suited to the opera-
tion of membrane bioreactors, because in this range the
mixed liquor has good filterability characteristics, and
the oxygen input can be managed in an economic way.
The sludge volume index, SVI, has no relevance for
membrane bioreactors.
As a result of the higher TSBB content of 10 – 15 g/l in
membrane bioreactors, according to module types and
recommendations of the manufacturers, at equal sludge
loadings, the activated sludge tank volumes are three to
four times smaller, compared to conventional activated
sludge stages, at equal sludge loadings. The smaller volume
tors” [ATV-DVWK 2000a], presented in Figure 2-23, have
to be considered since, due to the higher sludge age, the
usual approach for determining the excess sludge produc-
tion is not valid.
83
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
exce
ss s
lud
ge
[kg
TS/
kg B
OD
5]
0.001 0.01 0.1 1
sludge loading [kg BOD5/(kg·TS·d)]
1.2
1.0
0.8
0.6
0.4
design rangeTS0/BOD5
minimal excess sludge production nutrient removal tTS=15d
Figure 2-23
Specific excess sludge production in membrane bioreactors [ATV-DVWK 2000a]
Membrane Technology in Municipal Waste Water Treatment2
of the activated sludge tanks as well as the volume of the
final clarifiers which does not exist in the case of mem-
brane installations are relevant to the buffering capacity
and the degradation efficiency because of shorter hydrau-
lic retention periods.
In order to comply with discharge standards for nitrogen,
it is therefore necessary to maintain for the critical design
case a minimum retention period in the activated
sludge tank. The recommendation of a necessary minimum
retention period of 6 h (or 8 h for more far-reaching
demands) at a design temperature of 10 °C for the critical
design case can be undercut, if the necessary volume of
the membrane installation would be larger than the
volume of the activated sludge tanks which results in
conventional design with a volume allowance of up to
50 % (with a chosen TSBB = 10 – 15 g/l in the activated
sludge stage). It has to be considered absolutely that the
nitrification volume of the membrane installation (with
VDeni, MBR / VNitri, MBR = 1), due to the volume limitation
(VMBR, max = 1,5 · VBB, conventional, 10-15 g TS/l ), will not be smaller
than the necessary nitrification volume with conventional
design (at a chosen TSBB = 10 – 15 g/l in the activated
sludge stage). The necessary tank volumes can be provided
by designing larger activated sludge tanks or by designing
supplemental balancing tanks. The recommendations
concerning the necessary retention period, the relation
between nitrification and denitrification volume of the
membrane installation as well as the volume limitation
to the 1.5-fold volume of the activated sludge tanks with
conventional design (at a chosen TSBB = 10 – 15 g/l in the
activated sludge stage) are based on simulation studies
carried out at the Institute of Environmental Engineering
of RWTH Aachen University. The effluent concentrations
of a fictitious conventional waste water treatment plant
and a ficititious membrane bioreactor with a connection
size of 100,000 PE were modelled with varying membrane
bioreactor volume. Assuming that the standard parameter
set (e. g. BORNEMANN ET AL. for the Activated Sludge
Model No. 1) is also valid for membrane bioreactors and
considering a fluctuation factor of 1.7 and a given design
load, the resulting effluent concentrations of both simu-
lated waste water treatment plants were comparable, at a
membrane bioreactor volume which leads to a hydraulic
retention period of 6 h for the critical load case.
The critical load case may occur during combined water
flow as a result of flushing water hammers with NH4-N
peak concentrations occurring in parallel in the inflow.
However, if there are no such peak concentrations at
combined water flow, but only peak concentrations at
dry weather flow depending on the time of the day, the
critical load case has to be explained with the help of
concentration hydrographs recorded during a representa-
tive period.
The recommendation of a minimum retention time of
6 h for the decisive load case and at a design temperature
of 10 °C represents the current state of knowledge. With
the help of the knowledge acquired with the operation
of membrane bioreactors, the current recommendations
for the design of membrane bioreactors are further devel-
oped.
The smaller reactor volume of membrane bioreactors has
an effect not only on possible breaking through of peak
inflows, but also on the capacity of the denitrification
stage. In large-scale membrane bioreactors, typical facili-
ties are constructed up to now with upstream denitrifica-
tion tanks. As a result of the smaller activated sludge
tank volume, undesired effects may occur, e. g. increased
oxygen carry-over from the nitrification or filtration zone
to the denitrification zone. This effect is reinforced by
high recirculation rates from the filtration zone.
In order to reduce the effects of increased oxygen carry-
over, the volume of the denitrification zone has to be
equated with that of the nitrification zone (VDN : VN = 1),
in contrast to the design of conventional activated sludge
stages. In order to take different operating states into
account, part of the denitrification zone should be design-
ed as a variable zone. This zone with a size of approx.
30 – 50 % of the denitrification zone, must be arranged
in the activated sludge tank according to the require-
ments of operation. It is also possible to credit the filtra-
tion zone for the nitrification volume. In this case it is
necessary to consider the operating mode of module
aeration as well as the lower oxygen input value (refer to
section “Demand for aeration of the membrane modules”).
84
Membrane Technology in Municipal Waste Water Treatment 2
To avoid oxygen carry-over into the denitrification zone
and to optimize oxygen utilization in the nitrification
zone, relaxation zones should be provided upstream of
the sludge recirculation flow.
If the filtration zone is separated from the other zones, it
might be useful not to recycle the return sludge into the
nitrification tanks rather than the denitrification tanks.
In this configuration it is possible to control both inter-
nal cycles – recirculation sludge from the nitrification
stage into the denitrification stage and return sludge from
the membrane stage – independently from each other.
The measures mentioned may contribute to reduce the
VDN/VN ratio.
In order to obtain phosphorus effluent values according
to the discharge standards, phosphate precipitation
should be carried out according to the proven recom-
mendations (e. g. ATV-DVWK-A 131, N. N. 2000b]). Nor-
mally a precipitant is dosed into the activated sludge
stage, i. e. simultaneous precipitation takes place. The
increased specific excess sludge volume resulting from
simultaneous phosphate elimination by precipitating
salts can be determined according to the ATV standard
A 202 [OHLE 2001].
Design of the membrane filtration stage
By analogy with the conventional activated sludge pro-
cess, the phase separation, i. e. the membrane stage, has
to be dimensioned for membrane bioreactors. In con-
trast to conventional activated sludge stages, the typical
membrane bioreactor design total solids content TSBB of
10 – 15 g/l has a non-quantifiable influence on the
dimensioning of the membrane surface to be installed.
The following factors have to be taken into account in
dimensioning and calculation of the membrane
stage and the membrane surface area required:
• maximum inflow to the membrane bioreactor and the
maximum effluent flow
• the performance data of the membrane modules utilized
(surface-specific flow) depending on the features of the
medium to be filtered (temperature, viscosity, etc.)
The membrane surface should be dimensioned in such a
way that the surface-specific flows allow for a constant
operation of the membrane modules, even in the case of
peak flows. Short events, i. e. for a few hours, where the
maximum flow is exceeded, are possible but should be
avoided with a view to long-term maintenance of a
high permeability. With new or cleaned membranes,
the permeability rates are usually in a range of more than
150 – 200 L/(m2· h · bar). In-tensive cleaning is normally
necessary at a permeability < 100 L/(m2· h · bar).
If the design concept for the installation is that one or
more module cassettes or filtration lines are permanently
in a cleaning cycle (e. g. in larger installations), the sur-
faces being cleaned must be excluded when dimensioning
the membrane surface area.
When determining the necessary membrane surface area,
internal process water quantities, e. g. from screen clean-
ing, have also to be considered.
Experience acquired with membrane bioreactors in ope-
ration has shown that it is possible, with the membrane
modules commercially available, to apply a net design
flux of 25 L/(m2· h ) at temperatures of the mixed liquor
of 8° C, based on the effluent flow of the complete instal-
lation. With a design temperature of 10° C this range may
be higher by 15 % [ATV-DVWK 2000a].
Design of the aeration equipment
With the membrane bioreactor process, the higher TS
content in the activated sludge tank leads to higher
viscosity of the mixed liquor compared to conventional
activated sludge stages. This has an influence on the
material transfer and the oxygen transfer coefficient �,
as shown by Figure 2-24.
85
Membrane Technology in Municipal Waste Water Treatment2
This factor has to be considered in the design of the
aeration equipment for oxygen transfer. Oxygen transfer
measurement in the activated sludge stages of the Mark-
ranstädt and Rödingen waste water treatment plants have
shown a decrease in the �-value with rising solid matter
content (Figure 2-24). �-values of 0.75 have been measured
with a TS content of 7 g/l, they decreased to 0.4 with a
TS content of 17 g/l.
If TSBB = 12 g/l is selected as the basis for the calculation
of a membrane bioreactor, an �-value of 0.6 should be
chosen for the oxygen transfer. This corresponds approxi-
mately to the �-values of conventional installations with
fine bubble aeration [CORNEL ET AL. 2001].
The necessary blower power for the overflow of the
membrane modules can be estimated as 7.5 – 25 W
per m2 of membrane surface installed, depending on the
module. Since the demand for aeration as well as the
aeration strategies (coarse or medium bubbles, perma-
nent, intermittent) strongly depends on the concepts of
the module manufacturers, the design of the aeration is
normally realized by the manufacturers. Further reduc-
tions of the aeration demand of membrane stages can be
expected as a result of improved module concepts (see
chapter 2.1.2).
The oxygen transfer taking place together with the
aeration of the membrane modules can be credited for
the biological degradation. The respective �-value should
be assessed as 0.17 – 0.20 (TSBB = 16 – 10 g/l) [SEYFRIED
2002].
Sludge treatment
First experiences acquired with the treatment of sludge
from membrane bioreactors have shown that the sludge
qualities do not differ very much from aero-bically stabi-
lized sludge from conventional installations. Tests for
dewatering aerobically stabilized sludge at the Rödingen
waste water treatment plant and the Büchel pilot plant
have shown that dried solid matter contents of 25 – 30 %
can be obtained with the usual aggregates (chamber filter
press, centrifuge), under equal operating conditions and
with a comparable demand for flocculants [ENGEL-
HARDT ET AL. 2001; N. N. 2003c; DICHTL, KOPP 1999;
86
1.0
0.8
0.6
0.4
0.2
0
alp
ha
valu
e[-]
Markranstädt
5 10 15 20
TS content [g/l]
Rödingen
Figure 2-24
Oxygen transfer coefficient (�-values) of the Rödingen and Markranstädt waste water treatment
plants with fine-bubble diffuser aeration [CORNEL ET AL. 2001]
Membrane Technology in Municipal Waste Water Treatment 2
BRANDS ET AL. 2000; VAN DER ROEST 2001; DRENSLA
ET AL. 2001].
Concerning the digestibility of sludge from membrane
bioreactors, similar values as for sludge from conventio-
nal plants have been determined for simultaneous
aerobic sludge stabilization with the help of the specific
digester gas production [BRANDS ET AL. 2000; VAN DER
ROEST 2001].
2.1.3.2
Mechanical Design and Planning
Concerning mechanical design and planning, membrane
bioreactors do not differ considerably from conventional
activated sludge plants. This is also true for possible failure
scenarios which have to be considered e. g. for approval
planning. Therefore only those aspects that additionally
have to be taken into account compared to conventional
municipal waste water treatment plants are mentioned in
the following.
Mechanical pretreatment
For the membrane bioreactor process, mechanical treat-
ment of the inflowing waste water is especially important.
From experience with large-scale installations it is known
that the membrane modules used are susceptible to accu-
mulation and sticking of fibrous material and therefore
to clogging [BAUMGARTEN 2001a]. This results in an
insufficient flow across the membrane surface which leads
to a reduction of the performance or may even cause
damage of the membranes [ENGELHARDT ET AL. 2001].
Therefore all undesired material such as grease, hair or
other coarse matter has to be removed from the raw
waste water. This has to be done much more carefully
than in conventional activated sludge plants. The quality
of pretreatment does not only depend on the features of
the influent, but also on the membrane module used. For
capillary membranes, mechanical pretreatment consist-
ing of a fine screen in the inlet zone (3 – 5 mm), follo-
wed by a sand and grease trap as well as a fine sieve with
a slit width of < 1 mm is recommended [MEYER 2001;
DRENSLA 2001]. Experiences with plate membranes have
shown that pretreatment with a 3 mm screen as well as a
sand and grease trap is sufficient because they show less
tendency to accumulation and sticking of fibrous matter
[N. N. 2000c].
In order to meet the requirements for pretreatment for
membrane bioreactors, the screen manufacturers have
already developed new products. An example is the
membrane screen offered by the company Huber AG
(Figure 2-25) for finest screening of the raw waste water
in the inlet to a membrane bioreactor stage.
87
Figure 2-25
View and principle of a screening facility for
membrane bioreactors (Markranstädt waste water
treatment plant) [HUBER 2002, STEIN 2002a]
Membrane Technology in Municipal Waste Water Treatment2
Design of the installation with view to failure
scenarios
Compared to conventional activated sludge plants, in the
case of membrane bioreactors failures have to be consi-
dered which affect the performance of the membrane
stage. Total breakdown of the membrane stage is the worst
case scenario for these installations, similar to the failure
of the secondary settlement tanks in conventional plants.
Therefore the pretreatment stages (screen, sand and grease
trap and, if necessary, separator for light density material)
of membrane bioreactors, being critical to the long-term
functioning of the membranes, have to be designed with
careful attention to breakdowns caused by common failure
scenarios that can be excluded in the design of conven-
tional municipal plants. Accidents in the catchment area
of the waste water treatment plant must also be considered.
In the case of critical influents due to accidents in the
catchment area of waste water treatment plants, the inlet
of the membrane bioreactor stage has to be closed, if
necessary, to avoid intoxication of the biomass as well as
damage to the membranes. This can be realized by special
sensors (e. g. conductivity sensors) in the inlet zone of the
waste water treatment plant so that sewers with storage
capacity and overflow, and stormwater overflow tanks
(e. g. unused primary settlement tanks) can be activated
in the case of accidents. The storage volume should be
calculated in such a way that in the case of combined
waste water flow, the influent to the membrane bioreac-
tor can be stored for two hours. In this case the mixing
and equalizing tank volume mentioned in chapter 2.1.3.1
can be taken into account with a view to maintaining
the minimum retention period. However, the impound-
ment or storage volume which is necessary to comply
with the standards for combined water treatment (ATV
standard A 128) must not be set off with the buffer vol-
ume to be installed.
It is also possible to build scum-boards and discharge
devices so that in the case of critical and unauthorized
indirect discharges, e. g. oil, petrol etc., a direct charge of
the membranes can be prevented.
Design of the installation with view to the arrange-
ment of membrane surfaces and reactors
In the case of new constructions, the membrane stage
should be designed in principle in two lines which are
hydraulically uncoupled, i. e. separate tanks including the
peripheral equipment, in order to allow for separate opera-
tion of each line for the complete inflow from the activated
sludge tank. The system has to be dimensioned hydrauli-
cally for these inflow volumes. Allowances for the permeate
capacity of the membranes are necessary if the capacity
reserves of the membranes have already been completely
utilized in the design of the installation for Qmax.
The same is true for installations with three or four lines,
for which the operational breakdown of one line has to be
considered in planning. Concerning multiple-line (> 4)
installations, the membrane stages should be calculated
in such a way that the maximum water volumes can be
treated, under design conditions, by 80% of the membrane
surface area available.
The mechanical design of the membrane stages should be
realized in such a way that in the case of necessary mem-
brane replacement, the above mentioned minimum mem-
brane surface in waste water treatment plants < 10,000 PE
(corresponding to a combined water flow of Qm < approx.
246 m3/h, i. e. a daily in-flow of Qd < approx. 2,250 m3/d)
can be quickly removed and installed, replaced or cleaned,
if necessary. The membrane suppliers have to ensure that
the membrane surfaces required are available and ready for
installation within two or three working days. Concerning
single-line installations, it must be possible to install the
membrane surfaces during operation (filled tanks).
For plants with more than 10,000 PE (corresponding to a
combined water flow of Q m > approx. 246 m3/h or a daily
inflow of Q d > approx. 2,250 m3/d)1), both requirements
mentioned in the last sections are of secondary importance
because even with indirect discharges caused by failures,
damaging of the complete membrane stage is rather im-
probable as a result of dilution effects. Moreover, larger
installations can be designed with multiple lines if suffi-
cient capacity reserves are available.
88
1) Assumptions according planning standard ATV-DVWK-A 131 [ATV-DVWK 2000c]: xs = 14 h/d, xf = 24 h/d, specific infiltration water flow = 0.5·QS,
Qm = 2·QS+Qf
Membrane Technology in Municipal Waste Water Treatment 2
Measurement, control and regulation technique
Besides the measurement, control and regulation techni-
que applied today at municipal waste water treatment
plants, additional parameters to be measured have to be
considered when using membrane technology. In parti-
cular, the permeability of the membranes has to be ob-
served and recorded separately for each line. This is neces-
sary in order to ensure that cleanings are carried out in
time so that a sufficient permeate capacity is maintained.
Within the scope of these measurements, suction pressure
and flow have to be recorded online, considering con-
struction measures and hydrostatic influences on the
pressure measuring. Inhibiting influences in flow measure-
ment have to be excluded.
For operation and cleaning of the modules, the require-
ments according to the recommendations of the manu-
facturers (e. g. pause control, backwash periods and volume
flows, alarm in the case of module aeration failure) have
to be taken into account.
Power supply
For possible power failures, a stand-by power supply
should be provided similar to conventional plants, in
case a two-side current input to the waste water treat-
ment plant is not possible. Anyway the process control
technique as well as the permeation have to be supplied
with power, and the power demand for minimum module
aeration (about 25 – 30 % of the design value) has to be
ensured.
Buffer tanks or reserves in the freeboard height are also
possible which allow for impoundment operation during
a short period.
Membrane cleaning
To maintain the filtration capacity, regular cleaning of
the membrane modules is necessary, which may take place
either in the activated sludge tank/filtration tank or in
separate tanks. Depending on the concept of the mem-
brane manufacturers, heating for the separate tank or the
cleaning solution has to be provided.
Since the cleaning agents to be used have caustic, oxidiz-
ing or corrosive effects, requirements concerning the
choice of materials for tanks (e. g. plastic sealings) and
aggregates (e. g. high-grade steel, PE) as well as for safety
at work (e. g. discharge devices for gases (chlorine), accord-
ing to the recommendations of GUV or DVGW for MAC
values) have to be considered in planning.
Appropriate tanks or stockrooms have to be provided for
the storage of the chemicals necessary for the cleaning
solutions.
2.1.3.3
Operation
Measures for maintenance of the filtration capacity
For safe operation of a membrane bioreactor, the mainte-
nance of a sufficient filtration capacity is of similar im-
portance as the maintenance of the settlement features
of activated sludge in a secondary settlement tank. While
in conventional plants the settlement features of the acti-
vated sludge can be influenced only to a limited extent
(e. g. floating sludge, bulking sludge or problems with
foaming), the filtration capacity of membrane bioreactors
can be maintained by regular operational measures, i. e.
membrane cleanings.
Cleaning is necessary for all membranes available on the
market, since in spite of sufficient pretreatment and module
aeration, the permeability of the membrane modules and
thus the flow performance at constant transmembrane
pressure, starting from a design flow rate of e. g. 25 L/(m2·h),
decreases continuously during operation. This reduction
of the performance is due to an increase in the resistance
to filtration by organic and inorganic covering layers on the
membrane surface and clogging of the membrane pores,
which cannot be avoided by operational measures such
as overflow and possible backwash of the membranes.
For maintenance or intensive cleanings, acid, alkaline
and oxidative cleaning agents are used which are suited
to restore the original filtration capacity.
In each case the instructions of the membrane or module
manufacturer have to be observed, since the cleaning
89
Membrane Technology in Municipal Waste Water Treatment2
methods may vary considerably according to the specific
module.
Maintenance cleanings are performed in situ in the
activated sludge. They take place regularly once or twice
a week using low concentrations of cleaning agents (e. g.
150 mg/L of active chlorine). They are used for example
for ZeeWeedTM and Puron modules. During an extended
backwashing phase, the cleaning agent is added to the
permeate and pumped into the modules which are
immersed into the mixed liquor.
Intensive cleanings with higher concentrations of
chemicals (e. g. 500 – 2,000 mg/L of active chlorine) have
to be performed every 3 to 6 months, depending on the
degree of contamination. By analogy to maintenance
cleanings, the modules are cleaned while they are im-
mersed (in situ) or in separate tanks (ex situ). With
At present the use of sodium hypochlorite as cleaning
agent provides the best results. However, high concen-
trations of cleaning agents may have negative effects
such as damage of the biomass and foaming of the acti-
vated sludge stage, so that overdosing must be avoided.
Especially in the case of in-situ cleanings, negative effects
on the effluent quality may occur due to e. g. increased
AOX concentrations in the permeate. But this can be pre-
vented by permeate recycling into the biological stage. In
the course of studies on the pretreatment of rinsing
waters from extensive external cleaning, pretreatment
methods are being developed which shall reduce the AOX
concentration in the rinsing waters and avoid foaming in
the waste water treatment plant [DRENSLA, SCHAULE
2004].
At present less critical cleaning agents such as hydrogen
peroxide or citric acid are being tested in some mem-
brane bioreactor installations, so that soon alternatives
for sodium hypochlorite will be available.
installed modules, cleaning takes place in the activated
sludge, in cleaning solution or on air. In this case the
filtration tanks are emptied so that the modules are
suspended freely.
External cleaning (ex situ) is realized at cleaning solution
temperatures of 30 – 35 °C. For better mixing, the mem-
brane can be aerated during the cleaning process, so that
the chemicals are distributed more evenly. External clean-
ing provides the best result, but this method requires
higher operating expense [DRENSLA, SCHAULE 2004].
Table 2-3 summarizes the cleaning methods for immersed
membrane systems.
Due to the high concentrations of chemicals, intensive
cleanings may damage organic membrane materials and
thus have negative effects on the membrane service life.
90
in the activated sludge The chemicals are dosed from the permeate side.
in the cleaning solution The tanks are emptied and filled with the cleaning Cleaning in a separate cleaning cell, the
solution, the cleaning solution is dosed from the chemicals are dosed from the feed side at
feed side. temperatures of 30 – 35 °C.
on air The water level is lowered, the chemicals are
dosed from the permeate side.
Table 2-3
Cleaning methods
Membrane modules installed (in situ) Membrane modules removed (ex situ)
Membrane Technology in Municipal Waste Water Treatment 2
Energy demand
In existing membrane bioreactors, specific energy con-
sumption rates of 0.8 to 2.0 kWh/m3 of permeate were
determined. Approximately 50 – 80 % of this value is
used for module aeration, which, however, provides most
of the oxygen transfer necessary for biological treatment.
The throughput of the installation, the TS content (oxy-
gen transfer coefficient) and the waste water temperature
have been identified as the main factors influencing the
specific energy demand. At present, the specific energy
demand of membrane bioreactors is still higher than that
of conventional waste water treatment plants, but the
effluent quality concerning hygiene-relevant parameters
is better. For the Markranstädt and Monheim waste water
treatment plants, the specific energy demand related to
the average inflow volume in the range of 0.8 kWh/m3 –
0.9 kWh/m3 [DWA 2005]. The fluctuation ranges for dif-
ferent parts of the specific energy demand (e. g. cross-flow
aeration, permeate/recirculation, additional demand for
aeration) are indicated in the DWA working report [DWA
2005] (see Annex 6).
Figure 2-26 presents by way of example the specific
energy consumption rate of the Markranstädt waste
water treatment plant as a function of the throughput.
The energy consumption rate of the membrane stage
(suction pumps and module blowers), the recirculation
pumps, the agitators, the fine-bubble blowers, and the
inlet structure have been considered.
While the energy consumption of recirculation pumps,
agitators and inlet pump station are nearly independent
of the throughput, clear dependencies exist for the opera-
tion of the membrane stage and the fine-bubble aeration.
It has been shown that with larger waste water flows
to be treated, the specific energy consumption rate of the
membrane stage is 22 % lower than for a smaller through-
put. The same tendency is observed for the specific ener-
gy demand of the fine-bubble aeration. In this case the
energy demand can be reduced by 48 %. Energy is saved
by increasing the performance of the fine-bubble aera-
tion and switching off the coarse-bubble aeration during
91
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
spec
ific
en
erg
y d
eman
d [
kWh
/m3 ]
membrane stage(suction pumps)and module aeration
recirculation pumps
agitators
fine-bubble aerators
inflow pumping station
1,000-1,500
plant throughput [m3/d]
2,000-2,500 > 3,000
0.12
0.21
0.05
0.16
0.88
0,090.01
0.14
0.85
0.1
0.11
0.69
0.01 0.010,01
Figure 2-26
Energy demand of a membrane bioreactor (8,000 PE) with simultaneous aerobic sludge stabilization
[STEIN ET AL. 2001]
Membrane Technology in Municipal Waste Water Treatment2
filtration pauses, or by reducing the performance of the
fine-bubble aeration at continuous coarse-bubble aeration
during filtration [STEIN ET AL. 2001].
Due to ongoing optimizations in plant operation as well
as module design and overflow, further reduction of the
energy consumption rate can be expected. Early develop-
ments such as the introduction of intermittent aeration,
two-storey arrangement of modules on top of the air
injection device, and operation of rotating membranes
has already resulted in a reduction of overflow-specific
energy costs by approx. 50 %. The Kommunale Wasser-
werke Leipzig (municipal waterworks) expect that the
energy consumption for MBR treatment will ultimately
be reduced to the range of conventional plants [STEIN
ET AL. 2001].
Manpower requirements and qualification
Besides training and sensitization of personnel for addi-
tional problems which result from the operation of a
membrane bioreactor (e. g. concerning membrane opera-
tion, cleaning, emergency operation in case the measure-
ment, control and regulation systems break down), there
are no extra demands on staff qualification.
Experiences from the Rödingen waste water treatment
plant (3,000 PE) have shown that the personal expendi-
ture after start-up, repair of faults and a training period is
at present approximately 0.5 man-days per day. This
value is in the range of conventional plants of comparable
size run by the Erftverband [DRENSLA 2001].
During the start-up period of the Markranstädt waste
water treatment plant (8,000 PE), the necessary working
time expenditure was assessed as unsatisfactorily high.
This was due in particular to failures of the peripheral
equipment of the membrane stage. After improvement of
the operational stability, the working time expenditure is
now in the range of conventional activated sludge plants
or only slightly greater with a maximum of one additional
working hour per day [STEIN 2002a].
2.1.4
Investments and Operating Costs
2.1.4.1
Investments
The investments for the construction of a membrane bio-
reactor consist of the costs for the components of mecha-
nical pretreatment, biological waste water treatment and
biomass separation and, if necessary, for excess sludge
treatment. From the experience acquired to-date, the
savings potentials and additional costs for the investments
compared to conventional waste water treatment techno-
logy can be summarized as follows in Table 2-4.
Starting from the typical costs for conventional waste
water treatment technology [BOHN 1993; GÜNTHERT,
REICHERTER 2001], the savings made in process engineer-
ing (smaller tank volumes, secondary settlement and pos-
sibly more tertiary treatment steps become unnecessary)
with the membrane bioreactor process can be divided
among the investments for additional expenditures as well
as for the membrane separation stage itself. According to
RAUTENBACH ET AL. [2000], the savings potential for the
components of a membrane bioreactor which are not part
of the membrane stage were 20 – 30 % for a plant size of
100,000 PE (compared to a conventional activated sludge
plant with secondary settlement and sand filtration).
Assuming a typical specific cost at that time of 200 euro per
m2 of membrane surface installed (including peripheral
equipment such as pipes, suction pumps, measurement,
control and regulation equipment), nearly the same total
investment for both variations were required.
The results of the tender process for the construction of
the Kaarst waste water treatment plant (80,000 PE) in 2001
have turned out favourably for membrane technology. The
offers submitted for membrane technology (20.3 – 22.1
million euro) were 1.7 – 3.4 million euro lower than those
for a comparable conventional plant without advanced
treatment (23.7 million euro) [ENGELHARDT 2002].
Based on the costs of membrane bioreactors built to-date
and on the results of tenders for new projects, the follow-
ing categories can be used to assess the investment:
92
Membrane Technology in Municipal Waste Water Treatment 2
The inhabitant-specific costs have to be assessed be-
tween 250 and 1,400 euro. This margin is mainly due to
different drainage systems. With combined systems, the
complete installation has to be dimensioned for the com-
bined waste water flow (usually 2·QT). Conversely, the
membrane stage of plants with separate systems only need
half of the membrane surface area compared to a com-
bined system. Moreover, the surface-specific costs of the
membrane modules decrease with increasing installation
size, and therefore have to be considered in direct depend-
ence on the total investments.
The share of investments for the membrane stage
(including peripheral equipment, machinery and piping)
in the total costs is in the range of 30 – 60 %. This wide
range also depends on the drainage system. Additional
influencing factors are the underlying membrane and
module costs, which during the last years have shown a
downward trend. Moreover, in the course of further tech-
nical development an increase in the performance of the
modules can be expected, so that the membrane surface
area to be installed, and thus the specific costs for the
membrane stage, will decrease.
At present, specific module costs for the first invest-
ment (including peripheral equipment) of 75 – 150 euro
per m2 of membrane surface can be assessed. These values
vary according to membrane manufacturers and the surface
used. Based on the developments made in the course of
the last years, an increase in the number of module system
suppliers can be expected. Rising sales as well as increased
competitive pressure will also have positive effects on the
module costs. Figure 2-27 shows the development of the
membrane replacement costs over the last decade and
a forecast for the year 2005 according to CHURCHHOUSE,
WILDGOOSE [2000]. In addition, the module-specific
costs on the basis of the tender results of different German
waste water treatment plants are listed. According to this
cost curve, more significant cost reductions can be expec-
ted in future. For the Monheim waste water treatment
plant, for example, membrane replacement costs of 58 or
50 euro/m2 after a membrane service life of 7.5 or 8 years,
respectively, have been assessed [RESCH 2002; STEIN
2002b].
93
Mechanical pretreatment
Biological treatment
Biomass separation/
advanced treatment
Sludge treatment
activated sludge tank volumes 3 to 4 times smaller because
of operation at increased TS content of 12 to 16 g/L
secondary settlement tank not necessary downstream
processes for further treatment of the biologically treated
waste water at higher demands on the effluent (sand
filtration, disinfection) not necessary
usually no anaerobic sludge stabilization (digester) because
the biomass is aerobically stabilized
finer mechanical pretreatment
• hollow-fibre membranes ≤ 1 mm
• plate membranes ≤ 3 mm
necessary to protect the membrane modules
costs for the membrane stage are higher than for con-
ventional secondary settlement tanks due on the one
hand to the costs of the membrane modules themselves
and on the other hand to peripheral equipment (measure-
ment, control and regulation equipment, piping, suction
pumps, compressors, cleaning facilities etc.)
higher energy costs due to aerobic sludge stabilization,
no utilization of digester gas from primary and secon-
dary sludge (with plants > 50.000 PE)
Table 2-4
Savings potentials and additional costs concerning the investments of membrane bioreactors compared to
conventional activated sludge plants
Process stage Savings potential Additional costs
Membrane Technology in Municipal Waste Water Treatment2
2.1.4.2
Operating and Maintenance Costs
The annual operating and maintenance costs related to
waste water volumes or the population connected consists
of different cost types. Compared to the costs of conven-
tional waste water treatment processes, the following dif-
ferences result for the membrane bioreactor process:
1. Energy costs:
Operation of a membrane stage requires more energy
than that of conventional plants. From the operation
of existing installations ≥ 3,000 PE, energy consump-
tion rates of 0.8 – 1,4 kWh per m3 of waste water treat-
ed have been determined. For the Nordkanal waste
water treatment plant, an energy demand approx. 60 %
(0.8 kWh/m3) greater than for conventional plants
(0.46 kWh/m3 with anaerobic sludge stabilization and
0.51 kWh/m3 with aerobic sludge stabilization) can
be expected [ENGELHARDT 2002].
2. Membrane cleaning:
To maintain the filtration capacity, the membranes
have to be cleaned regularly. Therefore, the costs for
chemicals (about 0.25 – 1.00 euro/(m3· a) and additio-
nal labour costs have to be taken into account.
3. Maintenance:
The typical cost for the maintenance of conventional
plants increases for membrane bioreactors due to the
additional expenditure for maintenance of the mem-
brane stage. The costs to be assessed result from the
real membrane service life (i. e. guaranteed by the
manufacturer; assumed up to now: 5 – 8 years, in
some cases 10 years [WOZNIAK 2002]) and from the
anticipated membrane replacement costs. The main-
tenance costs decrease with longer service life and
falling module costs.
94
450
400
350
300
250
200
150
100
50
0
mem
bra
ne
rep
lace
men
t co
sts
o/m
2
1990year
1995 2000 2005
1 Specific net costs for installed membrane surface area (without peripheral equipment, first installation), calculated back on the basis of theresults of the call for tenders; according to information from the manufacturers, low costs can be expected for membrane replacement.
2 Estimation of the operator [STEIN 2002b]
KA Monheim9.700 PE
KA Rödingen1
3.000 PE
GKW Nordkanal1
80.000 PE
KA Markkleeberg2
30.000 PE
KA Markranstädt1
8.000 PE
according to Churchhouse (2000) gathering ISA RWTH (2003)
Figure 2-27
Development of membrane replacement costs [ISA 2002; CHURCHHOUSE, WILDGOOSE 2000]
Membrane Technology in Municipal Waste Water Treatment 2
4. Waste water charges:
As a result of the treatment efficiency of membrane
stages, a reduction in the pollution load discharged
into water bodies can be expected.
The expenditure for the construction of a membrane
stage can therefore be cleared with the waste water
charges paid to-date, provided that the requirements
according to § 10 section 3 of the Waste Water Char-
ges Act are met.
Since the higher energy and maintenance costs exceed
the reduction in waste water charges, higher operating
costs of membrane bioreactors can be expected on the
whole. A comparison of operating costs has been realized
for the Nordkanal waste water treatment plant on the
basis of the offers [ENGELHARDT 2002]. According to
this study, the assessed waste-water-specific operating
costs of the membrane bioreactor (0.24 – 0.25 euro/m3)
were higher by approx. 15 % than that of the conventio-
nal solutions offered (0.20 – 0,22 euro/m3). Ranges for the
costs per year, related to energy demand and waste water
volume, for aeration and recirculation, the necessary
chemicals etc. are indicated in the DWA working report
“Membrane bioreactor process” (see Annex A 6 [DWA
2005]).
In this case it has to be taken into account that plants
with differing effluent qualities are compared in cost
determination. In order to obtain the same effluent qua-
lity with conventional activated sludge plants as with
membrane bioreactors, an additional treatment stage
(e. g. disinfection stage) has to be arranged downstream
of the conventional plant. Under this condition the ope-
rating costs of membrane bioreactors should be the same
or lower.
Moreover, further technical developments of the mem-
brane modules will lead in future to a reduction of the
energy costs and improvement of the performance, so
that the population-specific treatment costs will also
decrease.
2.2
Concrete Examples of Membrane Bioreactors
In the following chapters, membrane bioreactors for the
treatment of municipal waste water are described which
already have been realized or are under planning. The
concrete examples are arranged according to the loca-
tions (in or outside Germany) and the membrane process
applied (microfiltration or ultrafiltration). Large-scale
plants, pilot plants, small waste water treatment plants,
ship’s waste water treatment plants and mobile plants are
described.
In Germany, at present nine large-scale membrane biore-
actors with capacities between 700 and 80,000 PE are
operated. Five more installations will be put into opera-
tion by the end of 2005. Ten plants will then exist in the
state North-Rhine Westphalia (NRW). All installations
built in NRW have been promoted by funds from the state.
The state makes available additional funds for new appli-
cations and more far-reaching scientific studies which
especially aim at optimizing the treatment capacity and
the operating cost.
Table 2-5 gives an overview of the most important data
for the plants in Germany, which will be described in
detail in the following sections.
95
Membrane Technology in Municipal Waste Water Treatment2
96
Table 2-5
Data of the large-scale membrane bioreactors treating municipal waste water in Germany,
as of December 2004
Operator
Federal State
Plant
Capacity
Membrane
manufacturer
Module type
Process
Membrane
surface area
Bioreactorvolume
Maximum inflow
Sewer system
Start-up
Pretreatment
Special feature
Erftverband
North Rhine-
Westphalia
WWTP Nordkanal
80,000 PE
ZENON
capillary module
ultrafiltration
84,480 m2
9,200 m3
1,881 m3/h
combined system
December 2003
screen (5 mm)
grit and grease trap
rotary screen (0.5 mm)
Aggerverband
North Rhine-
Westphalia
WWTP Seelscheid
10,500 PE
Kubota
plate module
microfiltration
12,480 m2
2,310 m3
356 m3/h
combined system
August 2004
step screen (3 mm)
grit chamber
expansion at the site of
the WWTP
City of Monheim
Bavaria
Monheim WWTP
9,700 PE
ZENON
capillary module
ultrafiltration
12,320 m2
1,640 m3
288 m3/h
combined system
July 2003
fine screen (1 mm)
grit channel
Municipal Waterworks
Leipzig
Saxony
Markranstädt WWTP
at present 8,000 PE
up to 12,000 PE
ZENON
capillary module
ultrafiltration
7,360 m2
approx. 1.800 m3
180 m3/h
combined system
January 2000
two-stage screen
(up to 1 mm)
grit and grease trap
Erftverband
North Rhine-
Westphalia
Rödingen
3,000 PE
ZENON
capillary module
ultrafiltration
4,846 m2
480 m3
135 m3/h
combined system
June 1999
screen (3 mm) grit and
grease trap sieving of
the recirculation sludge
(0.5 mm) in partial flow
Operator
Federal State
Plant
Capacity
Membrane
manufacturer
Module type
Process
Membrane
surface area
Bioreactorvolume
Maximum inflow
Sewer system
Start-up
Pretreatment
Special feature
Municipal Services
Schramberg
Baden-Württemberg
Schramberg WWTP
2,600 PE
ZENON
capillary module
ultrafiltration
4,400 m2
730 m3
90 m3/h
combined system
May 2004
screen (5 mm)
fine screen (0.5 mm)
grit and grease trap
Aggerverband
North Rhine-Westphalia
Büchel WWTP
1,000 PE
Kubota
plate module
microfiltration
960 m2
190 m3
40 m3/h
combined system
August 1999
screen (3 mm) grit
chamber, optional
primary treatment
pilot plant
Municipal Waterworks
Leipzig
Saxony
Knautnaundorf WWTP
at present 900 PE
up to 1,800 PE
Martin Systems AG
plate module
ultrafiltration
756 m2
68 m3
23 m3/h
separate system
October 2001
two-stage screen
(3 mm, 1mm)
grit and grease trap
Wasserverband
Eifel-Rur (WVER)
North Rhine-Westphalia
WWTP Simmerath
700 PE
PURON
capillary module
ultrafiltration
1,000 m2
136 m3
being studied
combined system
2003
fine screen (3 mm)
pilot plant
Membrane Technology in Municipal Waste Water Treatment 2
The positive experiences acquired to-date with membrane
technology and the membrane bioreactor are the reason
for water boards and municipalities to take the membrane
bioreactor process into consideration when planning new
or up-grading existing plants as an alternative to conven-
tional waste water treatment processes. Especially those
operators (Wasserverband Eifel-Rur (WVER), Erftverband)
who have acquired experience with membrane technology
are planning or building more membrane bioreactors
(Table 2-6).
Moreover, the application of the membrane bioreactor
process is studied at a large number of other sites in
Germany. The waste water plants at the sites Xanten-
Vynen (LINEG) and Richtheim (Municipality of Richt-
heim in cooperation with Bayerisches Landesamt für
Wasserwirtschaft (Bavarian Office for Water Manage-
ment)) are mentioned here by way of example, which
will also be described in the following chapters.
97
Table 2-6
Membrane bioreactors under construction or in planning stage in Germany, as of December 2005
Operator
Federal State
Plant
Design capacity
Planned start-up
State
Membrane
manufacturer
Module type
Process
Membrane surface
area
Bioreactor volume
Maximum inflow
Pretreatment
Special features
WVER
North Rhine-
Westphalia
WWTP Rurberg
6,200 PE
2005
commissioned
Kubota
plate module
microfiltration
approx. 13,440 m2
approx. 750 m3 planned
349 m3/h
fine screen (3 mm)
grit chamber
finest screen (0.5 mm)
discharge into
Rurtalsperre (Rur valley
reservoir)
WVER
North Rhine-
Westphalia
WWTP Konzen
9,700 PE
2005
commissioned
Kubota
plate module
microfiltration
23,040 m2
approx.1,700 m3 planned
587 m3/h
fine screen (3 mm)
grit chamber
finest screen (0.5 mm)
City of Eitorf
North Rhine-
Westphalia
WWTP Eitorf
11,625 PE
2005
commissioned
Kubota
plate module
microfiltration
10,240 m2
1,200 m3
288 m3/h
fine sieve
grit and grease trap
partly industrial waste
water
Linksniederrheinische
Entwässerungs-
Genossenschaft
North Rhine-
Westphalia
WWTP Xanten-Vynen
2,000 PE (only
membrane installation)
2005
commissioned
A 3 GmbH
plate module
microfiltration
2,000 m2
40 m3/h
screen (3 mm)
expansion of the WWTP
at the site
Erftverband
North Rhine-
Westphalia
WWTP Glessen
9,000 PE
2005
planning stage
not yet determined
not yet determined
micro-/ultrafiltration
12,320 m2 planned
approx.1,700 m3 planned
268 m3/h
screen (6 mm)
grit-/grease trap
fine sieve (0.5 mm)
expansion of the WWTP
at the site
MF2.2.1
MF2.2.1.1
Membrane Technology in Municipal Waste Water Treatment2
Waste Water Treatment Plants with Microfiltration
Membrane Installations in Germany
Seelscheid Waste Water Treatment Plant and
Training Centre
From 1974 to 1976, the Seelscheid waste water treatment
plant had been designed for 3,000 PE. In a second stage,
from 1991 to 1992, it was expanded to a capacity of
7,500 PE. The design at that time provided a final expan-
sion up to 10,500 PE so that some structures, in particu-
lar the pipes, were designed for that size. Upgrading of
the waste water treatment plant to 10,500 PE according
to the activated sludge process would have been very
expensive due to limited space. In 2003, the membrane
bioreactor suggested itself as a more effective alternative
with lower space demand.
For the expansion, two fine screens (3 mm spacing) were
installed in the existing screen building in order to ensure
trouble-free operation of the waste water treatment plant,
especially of the membrane installation. Each of both
fine screens is able to treat the maximum waste water
flow of 99 L/s, resulting in a redundant system. The
aerated grit and grease trap, which existed before the last
upgrade, has a volume of V = 104 m3. The calculated
hydraulic retention time in this structure is more than
17 min. in the case of stormwater flow and more than
35 min. during dry weather flow. After having passed the
grit chamber, the waste water flows into the activated
sludge tank which is built as a circular tank with differ-
ent zones. The waste water flows centrally into an an-
aerobic zone (V = 500 m3) for increased biological phos-
phorus removal. The outside zone of the activated sludge
tank (V = 1.160 m3) is used for denitrification. Part of the
tank (500 m3) can be aerated and used for nitrification,
depending on time and load.
The intermediate settling tank was decommissioned to
build the new three-line membrane stage on this surface,
which was commissioned in July 2004. The three mem-
brane tanks with a total volume of approx. 800 m3 serve
for nitrification. In each of the three tanks, 13 plate
membrane modules (type EK 400) from the company
Kubota are installed. The total membrane surface area is
12,480 m2. The recirculation flows and the aeration are
controlled by fuzzy logic.
At present, the necessary transmembrane pressure differ-
ence is produced in gravity flow and can be supported
by permeate pumps. The filtrate is fed into a storage tank
(V = 100 m3). From there it is discharged by the existing
pipes into the Wenigerbach (a creek). Part of the treated
waste water is used as process water at the waste water
treatment plant. The concentrate is recycled into the
denitrification zone or optionally into the aerobic zone.
The minimum requirements, the values of the discharge
consent and the operating values after four months of
operation are listed in Table 2-7.
The investment for upgrading of the Seelscheid waste
water treatment plant was approx. 4.6 million euro,
supported by funds from MUNLV.
98
Table 2-7
Minimum requirements, discharge consent and operating values of the Seelscheid waste water treatment
plant [according to AGGERVERBAND 2004]
Parameter
CSB
BSB5
NH4-N
Ntot
Ptot
AOX
Unit
mg/L
mg/L
mg/L
mg/L
mg/L
µg/L
Minimum requirements
90
20
10
18
2
no information
Discharge consent
40
10
3
18
0.8
50
Operating values
< 20
no information
< 0.1
< 5
–
–
Membrane Technology in Municipal Waste Water Treatment 2
99
feed
alternative
recirculation
fine screen3 mm
fine screen3 mm
denitri-fication-tank
nitri-fication-tank
anaerobictank
sludge
permeatestorage
blowerinstallation
process water
gritchamber
membrane stage/nitrification
receivingwater
Figure 2-28
Flow sheet of the Seelscheid waste water treatment plant [according to AGGERVERBAND 2004]
Figure 2-29
Membrane installation at the Seelscheid waste water treatment plant [photos: AGGERVERBAND 2004],
left: membrane tanks, right: machine cellar of the membrane installation
Membrane Technology in Municipal Waste Water Treatment2
Training centre at the Seelscheid waste water
treatment plant
The Aggerverband (water board) will establish at the site
of the Seelscheid waste water treatment plant a modern
training centre for membrane technology. This will be
done in cooperation with the Ministry for Environment
and Nature Conservation, Agriculture and Consumer Pro-
tection (MUNLV) of the state North-Rhine Westphalia,
the Bildungszentrum für die Entsorgungs- und Wasser-
wirtschaft (BEW) (Training Centre for Water Management
and Waste Water Disposal), the Deutsche Vereinigung für
Wasserwirtschaft, Abwasser und Abfall (DWA) (German
Association for Water Management, Waste water and
Waste), the Deutsche Gesellschaft für Membrantechnik
(DGMT) (German Association for Membrane Technology)
and the RWTH Aachen University. The centre is supported
by funds from the state North-Rhine Westphalia. Besides
training rooms and eight laboratory working places, four
membrane bioreactors with upstream denitrification and
various membrane systems will be installed in the tanks
of the former sand filtration system in order to realize
practical training (see Figure 2-31 and Figure 2-30).
The training courses are intended for environmental
technicians, sanitation masters and future engineers from
universities. Completion of the training centre is scheduled
for the year 2005. The training centre is promoted by
funds of the federal state North Rhine-Westphalia.
100
raw wastewater
optionalinflow
fine screen3 mm
fine screen0,75 mm
to treatment plant
raw wastewater
denitri-fication
nitrification/membrane stage
recirculation
recirculation
recirculation
recirculation
blowerinstallation
blowerinstallation
blowerinstallation
blowerinstallation
Figure 2-31
Flow sheet of the training installations [according to AGGERVERBAND 2004]
Figure 2-30
Existing sand filter tanks, to be used for the trai-
ning installations [photo: AGGERVERBAND 2004]
Membrane Technology in Municipal Waste Water Treatment 2
Büchel Pilot Plant
Within the scope of a research project “Upgrading of the
Büchel waste water treatment plant using membrane
technology” promoted by the Ministry for Environment
and Nature Conservation, Agriculture and Consumer
Protection (MUNLV) of the state North-Rhine Westpha-
lia, the Aggerverband (water board) has operated from
1999 to 2001 a membrane bioreactor pilot plant. This
R&D project was realized on behalf of Aggerverband by
the Institute of Environmental Engineering of RWTH
Aachen University and ATEMIS (consulting engineers).
The reason for the project was the necessary expansion
of the Büchel waste water treatment plant from the
existing capacity of 12,000 PE to 25,000 PE. Besides the
limited space available, stringent demands on the effluent
quality made by the district government Cologne, due to
the situation of the plant in a nature reserve, had also to
be taken into consideration. Therefore, the Aggerverband
searched for an alternative to conventional waste water
101
nitrification and membrane container V=80m3 permeate
nitri-/denitrification-tank V=100m3
feed
membrane stage 1 membrane stage 2
RS
blowerstationmembranereactor
blower stationnitrification
Figure 2-33
Flow sheet of the Büchel pilot plant [BAUMGARTEN 2001b]
Figure 2-32
View of the Büchel pilot plant [photo: ISA RWTH
AACHEN]. Foreground: filtration container. Back-
ground, left: activated sludge tank of the pilot
plant. Background, right: primary settling tank of
the overall plant
MF2.2.1.2
Membrane Technology in Municipal Waste Water Treatment2
treatment technology. After detailed cost comparisons,
the membrane bioreactor process turned out to be the
most interesting alternative. The Aggerverband decided
to run a pilot plant within the scope of expansion plan-
ning in order to acquire experience with this technology.
The pilot plant was situated at the site of the Büchel
waste water treatment plant and is fed with a partial flow
of the mechanically pretreated waste water from the exi-
sting plant. Mechanical pretreatment consisted of a
step screen (3 mm), an aerated grit and grease trap and a
primary settling tank. To feed the pilot plant, the partial
flow could be taken either upstream or downstream of
the primary settling tank.
The waste water was pumped by a lifting pump into the
denitrification zone of the pilot plant. Nitrification took
place only in the zone of the downstream membrane
stage (Figure 2-33) because under normal conditions the
air injected for the overflow of the membranes is sufficient
for complete nitrification. If this was not ensured, single
zones in the upstream denitrification tank could be aerated
and used for nitrification.
The membrane stage consisted of two filtration lines
which could be operated independently from each other.
Each line is equipped with four plate packages contain-
ing 150 plate modules from the company Kubota. The
treated waste water was withdrawn by suction from the
filtration modules.
After a start-up period during which faults of the mecha-
nical installation were remedied, the plant was operated
nearly trouble-free. After a six-month operating phase
where each of the filtration stages was operated with net
specific flows of 27 L/(m3·h), the transmembrane pressure
increased from approx. 80 mbar to average values of
approx. 150 mbar due to fouling. Therefore, chemical
in-situ cleaning had to be carried out in order to ensure
the throughput of the plant. With this it was possible to
restore the original membrane capacity nearly completely
[WOZNIAK, BAUMGARTEN 2001, BAUMGARTEN
2001b].
After conclusion of the pilot tests, an expansion at the
site of the Büchel waste water treatment plant according
to the conventional activated sludge process was pre-
ferred for economic reasons. However, as a result of the
experience acquired with membrane technology, the
Aggerverband favoured under technical aspects the fur-
ther use of membrane technology for municipal waste
water treatment. Thus the experience acquired was in-
cluded in the meantime e. g. in the expansion of the large-
scale Seelscheid waste water treatment plant of the
Aggerverband (see chapter 2.2.1.1). For future new con-
structions or expansions of plants, too, this technology
will be included in the studies of technical processes.
102
Membrane Technology in Municipal Waste Water Treatment 2
Richtheim Waste Water Treatment Plant
In Bavaria, many decentralized waste water treatment
plants are situated in regions with stricter requirements
for water pollution control (e. g. karstland) or discharge
into sensitive receiving waters, so that advanced waste
water treatment may be useful or necessary, e. g. by sand
filtration and UV disinfection, ozonation or membrane
technology.
Within the scope of a research project promoted by the
Landesamt für Wasserwirtschaft (LfW) (State Office for
Water Management) in Bavaria, different processes for
the treatment of municipal waste water in decentralized
waste water treatment plants are studied at three sites.
The study focuses on the attainable effluent quality,
operational liability and expenditure.
The Richtheim waste water treatment plant is used to
perform the studies on the membrane bioreactor process.
It has a treatment capacity of 100 PE.
An inflow shaft, installed for the separation of coarse and
floating matter, serves as primary settling tank for coarse
and floating matter. The pretreated waste water then
flows by gravity into the membrane bioreactor. The plate
modules from the company Kubota (2 module packages
with 80 m2 membrane surface area each), which include
aeration, are installed in a prefabricated shaft which serves
as the membrane bioreactor. The oxygen demand is
covered completely by aeration of the membrane mod-
ules. Figure 2-34 shows the flow sheet of the installation.
103
feed
primary treatment
blowerinstallation
membrane stageflow
receivingwater
Figure 2-34
Flow sheet of the membrane bioreactor [according to BAYERISCHES LANDESAMT FÜR WASSERWIRTSCHAFT
2004]
MF2.2.1.3
MF2.2.1.4
Membrane Technology in Municipal Waste Water Treatment2
Eitorf Waste Water Treatment Plant (Commissioned)
The Eitorf waste water treatment plant receives municipal
waste water from the municipality of Eitorf, parts of the
city of Hennef and the waste water from commercial and
industrial enterprises. For expansion of the capacity of
the plant from 33,000 PE up to now to approx. 46,500 PE
(value prognosticated for the year 2010), process variants
using membrane technology were developed within the
scope of a study [NOLTING, KAZNER 2005]. Based upon
the comparison of the costs per year, the construction of
a membrane bioreactor turned out to be the most favour-
able solution for the expansion of the capacity for the
treatment of a partial waste water flow.
The installation was originally intended for the joint tre-
atment of a high-loaded waste water flow from textile
finishing with strong coloration and high AOX concen-
trations (see Table 2-8). In order to increase the treatment
efficiency concerning these parameters (effluent require-
ment for AOX: 50 µg/L), simultaneous addition of pulver-
ized activated carbon was tested successfully in the run-
up on an industrial scale for the conventional plant
[KAZNER 2003] and on pilot scale for a membrane bio-
reactor [BAUMGARTEN 2005].
104
feed
receivingwater
primary treatmentfine screen3 mm
gritchamber
fine sieve1 mm
75 %
25 %
biological reactor
sludge
clarifier
variabletank
denitrifi-cation
recirculation
4-linemembrane stagewith nitrification
Figure 2-35
Flow sheet of the Eitorf waste water treatment plant [according to GEMEINDEWERKE EITORF 2004]
Table 2-8
Input values for the design of the Eitorf membrane bioreactor [according to GEMEINDEWERKE EITORF
(municipal utilities) 2004]
Parameter Qd Qh QM COD BSB5 TKN NH4-N Ptot AOX
Inflow to the membrane bioreactor 1,800 145 288 1,152 486 108 62 13 0,4
m3/d m3/h m3/h kg/d kg/d kg/d kg/d kg/d kg/d
Membrane Technology in Municipal Waste Water Treatment 2
Due to operations-related closure of the dye-works, this
waste water flow will cease in future. A high-loaded waste
water flow from the food industry will be introduced
instead.
The membrane bioreactor consists of a denitrification
tank (V = 300 m3), a variable zone equipped with aerators
(V = 300 m3) for denitrification or nitrification and four
nitrification tanks (150 m3 each), in which immersed plate
modules from the company Kubota (type EK 400, double-
decker modules) with a total membrane surface area of
10,240 m2 are installed.
The investments for the construction of the membrane
bioreactor, which was commissioned in September 2005,
were 3.9 million euro, subsidized in part by the Ministry
for Environment and Nature Conservation, Agriculture
and Consumer Protection of the federal state North
Rhine-Westphalia (MUNLV NRW).
105
Figure 2-36
Eitorf waste water treatment plant with covered membrane tanks between the buildings in the foreground
Membrane Technology in Municipal Waste Water Treatment2
Xanten-Vynen Waste Water Treatment Plant
(Commissioned)
In 1972, the Xanten-Vynen waste water treatment plant
was designed, according to the design principles at that
time, for 6,000 PE and triple dry-weather flow. Today the
biological stage is approved for 3,300 PE. At present,
approx. 3,160 PE are connected. Thus, the degree of capa-
city utilization is more than 95 % and has to be expanded
to 4,989 PE, due to anticipated population growth. The
connected quarters Vynen and Marienbaum are drained
for the most part by a combined sewer system. Only one
modern estate is drained by a separate system. The inflow
to the waste water treatment plant is exclusively of muni-
cipal origin.
Within the scope of a three-year research project, a two-
line membrane bioreactor at the Xanten-Vynen waste
water treatment plant will be equipped with the plate
membrane system from the company A3 and operated in
106
feed
screen gritchamber
screen system3 mm
biological reactor
sludge
clarifier
recirculation
effluent polishingpond
blowerinstallationrecirculation
denitrifi-fication
membrane stagenitrification
denitrifi-fication
membrane stagenitrification
receivingwater
Figure 2-38
Flow sheet of the Xanten-Vynen waste water treatment plant, including the planned membrane
bioreactors [according to LINEG 2004]
Figure 2-37
Membrane installation in container construction
for the Xanten-Vynen waste water treatment plant
[photo: A3 GMBH]
MF2.2.1.5
Membrane Technology in Municipal Waste Water Treatment 2
Piene Waste Water Treatment Plant
(in Planning Stage)
The construction of a waste water treatment plant with a
treatment capacity of 170 PE according to the membrane
bioreactor process is being planned for the quarter Piene
of the city of Gummersbach.
Until now, the waste water of Piene is treated by three-
chamber septic tanks. The treated waste water is discharged
into a “weak” receiving water, The discharge consent
requires a COD effluent concentration of < 70 mg/L and
a BOD5 concentration of < 10 mg/L. Due to the situation
described above, a decision was made in favour of the
membrane bioreactor process. Figure 2-39 shows the flow
sheet of the membrane bioreactor.
It is planned to pretreat the waste water by a rotary
screen with a spacing of 3 mm. The following buffer tank
wih a volume of 40 m3 serves to buffer peak flows in the
case of combined water flow and to store the excess sludge.
From the storage tank the waste water is fed into the
activated sludge stage (V = 40 m3) in which the immersed
membrane modules are integrated. It is intended to use
plate membrane packages from the company Kubota
with a total membrane surface area of 320 m2.
107
parallel (see Figure 2-38). The total capacity of the two-line
membrane bioreactor will be approx. 2,000 PE.
Both membrane bioreactors will be operated under real
conditions in parallel to the existing activated sludge stage
to compare the cleaning efficiency of both systems. The
three-year test period has the following objectives:
• To prove evidence of the operational safety and capacity
of the installation
• To study the economic efficiency of the membrane
system
• To determine an optimum operating and cleaning
management program
Both membrane installations are manufactured identically
and fitted in one container each (Figure 2-37). For mecha-
nical pretreatment, a screen with an aperture size of 3 mm
is planned. The activation volume is 100 m3 each. Each
membrane installation is designed for a dry weather flow
of 12.5 m3/h and a stormwater flow of 40 m3/h and has a
membrane surface area of 2,000 m2. The membrane instal-
lation will be commissioned still in 2005.
feed
buffer tank
biological reactormembrane stage
fine screen3 mm
sludge
receivingwater
Figure 2-39
Flow sheet of the membrane bioreactor [according to CITY OF GUMMERSBACH 2004]
MF2.2.1.6
MF2.2.1.7
Membrane Technology in Municipal Waste Water Treatment2
Rurberg-Woffelsbach and Konzen Waste Water
Treatment Plants (Commissioned)
The Rurberg-Woffelsbach and Konzen waste water treat-
ment plants of Wasserverband Eifel-Rur (WVER) (water
board) are being expanded to a treatment capacity of
6,200 PE and 9,700 PE, respectively. At present, both
expansion measures are realized. The plants will be put
into operation at the end of 2005.
The current demands on the effluents of the Rurberg-
Woffelsbach and Konzen waste water treatment plants
are listed in Table 2-9. The Rurberg-Woffelsbach waste
water treatment plant discharges into the Rur reservoir
which is used for recreation purposes, and the Konzen
waste water treatment plant uses the Laufenbach (a
creek) as receiving water which is situated in the drin-
king water catchment zone. These were the reasons for
the use of a membrane bioreactor at both sites.
In future, the Rurberg-Woffelsbach waste water treatment
plant will be designed for a dry weather flow of 175 m3/h
and a stormwater flow of 349 m3/h. The Konzen waste
water treatment plant will treat a dry weather flow of
245 m3/h and a stormwater flow of 587 m3/h.
The process concept for both plants includes mechanical
pretreatment by a fine screen with a spacing of 3 mm,
followed by a grit and grease trap and a fine screen with
a spacing of 0.5 mm. The fine screen will be redundant.
At the Rurberg-Woffelsbach waste water treatment plant,
biological waste water treatment takes place in an upstream
denitrification tank and a combined nitrification/mem-
brane tank.
At Konzen, an activated sludge tank both for denitrifica-
tion and nitrification precedes the membrane chamber.
Additional nitrification volume is available in the mem-
brane chamber. Both installations are equipped with plate
membrane modules from the company Kubota. At the
Rurberg-Woffelsbach waste water treatment plant, a
membrane surface area of 13,440 m3 will be installed,
and of 23,040 m3 at the Konzen plant. For these mem-
brane surface areas, 42 and 72 membrane-modules,
respectively, of the type EK 400 are provided. In this
region, the membranes have to cope with a waste water
temperature in winter of less than 6 °C.
According to the submittal results, the investments for
the Rurberg-Woffelsbach plant are approx. 5.5 million
euro (without planned lake duct, pumping station and
engineering) and 7.5 million euro for the Konzen plant
(without combined water treatment and engineering).
Taking into account a subsidy of 50 % by the federal
state North Rhine-Westphalia for the membrane-specific
costs, the expansion of both waste water treatment
plants by the membrane bioreactor process is less
expensive than conventional upgrading.
108
Table 2-9
Demands on the effluent quality of the Rurberg-Woffelsbach and Konzen waste water treatment plants
[according to WVER 2004]
Parameter Unit Demands on the effluent of the Demands on the effluent of the
Rurberg-Woffelsbach WWTP Konzen WWTP
CSB mg/L 80 50
BSB5 mg/L 20 15
NH4-N mg/L 10 3
Ptot mg/L 0.5 0.2
MF2.2.1.8
Membrane Technology in Municipal Waste Water Treatment 2
Kohlfurth Waste Water Treatment Plant,
Process Water Treatment
The Kohlfurth waste water treatment plant has a design
capacity of 156,000 PE. It treats mainly municipal waste
water by the conventional activated sludge process with
following anaerobic sludge treatment (see Figure 2-40).
Concerning nitrogen removal, the Kohlfurth waste water
treatment plant was designed for a monitoring value of
18 mg Ninorg/L. In future, it has to comply with a monitor-
ing value of 13 mg Ninorg/L. With full capacity utilization
of the plant, at present it cannot be assured that this
requirement is met in the qualified random sample. This
was the reason in autumn 2003 to plan a new treatment
facility for the process water from sludge dewatering.
At the Kohlfurth waste water treatment plant, the daily
sludge liquor quantity from sludge dewatering is 300 m3
with a NH4-N concentration of 700 – 1,000 mg/L. As new
treatment concept, the membrane bioreactor process was
chosen. The potential for autotrophic deammonification
in the membrane bioreactor will be studied in particular.
The sludge liquor is stored temporarily in a buffer tank.
It flows for nitritation into the first aeration reactor with
a volume of 200 m3. Autotrophic deammonification will
take place in the second aeration reactor (V = 180 m3).
Two thickeners which are no longer used, serve as reac-
tors for the activated sludge stage.
The two-line membrane installation arranged downstream
of the activated sludge stage is installed in a separate
reactor. Each line contains two module packages (from
the company Kubota, type EK 400) with a total membrane
surface area of 720 m2. The permeate of the membrane
installation is fed into the return sludge pumping station
and, with this, into the activated sludge stage of the
Kohlfurth waste water treatment plant.
The plant is working since January 2005. After a test ope-
ration phase, the operating mode of autotrophic deam-
monification as well as of conventional denitrification
will be studied.
109
primary treatment biologicalreactor
sludge
clarifier
denitri-fication
nitrifi-cation
feed
screengritchamber
denitri-fication
carbon source
gritfiltration
coarse sludge
pre-thickening
digester digester
post-thickening
chamberfilter press
sludge liquor
filtrate
membranestage
storage
sludgeliquor
recirculation
flow
receivingwater
Figure 2-40
Flow sheet of the Kohlfurth waste water treatment plant [according to WUPPERVERBAND 2004]
MF2.2.1.9
Membrane Technology in Municipal Waste Water Treatment2
Dormagen Waste Water Treatment Plant,
Process Water Treatment (Commissioned)
The Dormagen waste water treatment plant has a design
capacity of 80,000 PE and treats predominantly municipal
waste water. After mechanical pretreatment, the waste
water is treated according to the activated sludge process.
The sludge is anaerobically treated (see Figure 2-41).
The process water from sludge treatment consists of the
sludge liquor from the digester and the post-thickener as
well as the centrate water from the centrifuges. It is stored
temporarily in a balancing tank. The NH4-N concentra-
tion of this process water is approx. 800 mg/L, which
corresponds to a waste water load of approx. 15,000 PE.
Due to this load, the waste water treatment plant reached
its capacity limits from time to time. This was the reason
in autumn 2003 to plan a new sludge water treatment
plant.
The concept using the membrane bioreactor for the treat-
ment of the sludge water turned out to be favourable in
terms of technology and economic efficiency. The mem-
brane installation is planned with two lines and will con-
tain eight module packages from the company Kubota
(type EK 150) with a total membrane surface area of 960 m2.
The existing grit chamber will be converted to a nitrifica-
tion and denitrification stage in which the process water
from the storage tank is fed. The membrane installation
will be fitted in a container on the existing grit chamber.
The permeate of the membrane installation will be fed into
the inflow of the activated sludge tank for treatment.
The plant is under construction and will be put into
operation in 2005.
110
recirculation
clarifier
feed
thickening digester digester
post-thickening
sludge liquor
... water
membranestage
storage
sludgeliquor
recirculation
flow
gritchamberscreen primary treatment
denitri-fication
nitrifi-cation
bio-P nitrifi-cation
denitri-fication
sludge
blowerinstallation
centrifuge
if nec.sludgeliquor
receivingwater
Figure 2-41
Flow sheet of the Dormagen waste water treatment plant [according to CITY OF DORMAGEN 2004]
MF2.2.2
Membrane Technology in Municipal Waste Water Treatment 2
Installations Outside of Germany with
Microfiltration Membranes
Membrane technology has been used in municipal waste
water treatment since the nineties. The first large-scale
plants were built mainly in North America and Japan.
About 90 % of these installations have a capacity of less
than 100 m3/d. A larger plant with a design capacity of
about 5,700 m3/d is situated in Powell River, Canada. The
installations in North America and Asia are used nearly
exclusively to treat waste water from separate systems, at
differing cleaning requirements in the individual coun-
tries. Therefore, the experience acquired at those plants is
transferable only to a limited extent to European condi-
tions.
However, since 1998 the use of membranes in the field of
municipal waste water treatment has increased worldwide.
Beyond many small installations, the first large-scale
waste water treatment plant in Europe (with a capacity
of 1,900 m3/d) was put into operation in 1998 at Porlock,
England. In 2000, the Swanage waste water treatment
plant (Figure 2-42) on the South coast of England follow-
ed, with a capacity of 13,000 m3/d and 23,000 inhabi-
tants connected. Until the end of 2001 this was the largest
membrane bioreactor treating municipal waste water.
The installation, equipped with the Kubota system, is
situated directly on the beach and is hardly visible as a
result of complete casing.
In Great Britain, the membrane bioreactor process is well
established not only with a view to technical but also to
economic aspects, so that a possible use of this process is
examined in the case of each new construction or expan-
sion of a plant.
In other European countries, e. g. in Italy/Lake Garda, or
in Belgium, the first membrane bioreactors are being
planned or are under construction.
111
Figure 2-42
Aerial photograph of the Swanage waste water treatment plant [photo: AQUATOR GROUP]
MF2.2.2.1
Membrane Technology in Municipal Waste Water Treatment2
Glasgow Waste Water Treatment Plant, Scotland
The Glasgow central sludge treatment plant treats sludge
of industrial as well as municipal origin. Between 7,800
and 12,800 m3 of sludge with an average TS content of
2 – 2.5 % are treated daily, consisting not only of sludge
quantities produced locally, but also of sludge from the
cities Shieldhall, Dulmuir, Paisley, Dalmarknock, Glasgow
Catchment and Daldowie.
Sludge dewatering takes place in 12 centrifuges operated
in parallel, following a 5 mm screen and storage tank of
30,000 m3. The sludge is thickened to a TS content of
30 % TS and then dewatered in six dryers to 90 – 92 % TS.
About 200 – 450 m3 of sludge water are produced per day,
80 % of this quantity resulting from the centrifuges and
20 % from the dryers. This sludge water has COD con-
centrations of 3,000 – 4,000 mg/L and NH4-N concentra-
tions of 200 – 300 mg/L, which corresponds to a load of
approx. 180,000 PE related to NH4-N.
The sludge water is treated by a three-line fine screen
(bar distance: 3 mm). Biological treatment takes place in
an upstream-arranged denitrification tank (V = 2,300 m3)
and four nitrification tanks operated parallel (Vtotal =
9,400 m3), in which the membrane modules are immersed.
The four-line membrane installation consists of 128 plate
membrane modules of the type EK 400 from the company
Kubota with a total membrane surface area of 20,480 m2.
Effluent concentrations of 40 – 60 mg/L COD and
0.1 – 0.4 mg/L NH4-N are reached. The NO3-N effluent
concentration is 30 mg/L on average.
The sludge treatment plant presented in Figure 2-44 has
been operated since the year 2002.
112
sludge water
recirculation
fine screen3 mm
fine screen3 mm
nitrification, membrane stage
fine screen3 mm
blowerinstallation
denitrification
receivingwater
Figure 2-43
Flow sheet of the Glasgow sludge treatment plant [according to AGGERWASSER GMBH 2004]
Membrane Technology in Municipal Waste Water Treatment 2
113
Figure 2-44
Top view of the sludge treatment plant and of a tank of the membrane installation
[photo: AGGERWASSER GMBH 2001]
footprint membranes
aeration device
Membrane Technology in Municipal Waste Water Treatment2
Ebisu Prime Square Building Waste Water
Treatment Plant, Japan
The Ebisu Prime Square Building is a tower block in Tokyo
where all office rooms, sales space and restaurants are
housed on a total surface of 70.000 m2 (Figure 2-45).
When the tower block was built, a membrane bioreactor
was installed in the basement. The waste water is treated
to a degree that the permeate can be used as process water
for a laundry and for toilet flushing.
Figure 2-47 shows the flow sheet of the waste water treat-
ment plant. The composition of the raw waste water and
the permeate is listed in Table 2-10.
The installation was put into operation in April 1997 and
is dimensioned for a permeate volume flow of 189 m3/d.
Equipment, maintenance and operation of the installa-
tion are realized by the company Kubota. Until now, the
plate modules have been cleaned chemically once or twice
a year. The TS content is kept between 15 and 20 g/L.
The transmembrane operating pressure is between 0.05
and 0.1 bar.
114
Figure 2-45 (left): Ebisu Prime Square Building
Figure 2-46 (right): Waste water treatment plant
in the basement of the Ebisu Prime Square
Building [photos: AGGERWASSER GMBH 2004]
feed
blower
membrane stage
fine screen
permeate for laundryand toilet flushing
concentratedisposal
Figure 2-47
Flow sheet of the waste water treatment plant [according to AGGERWASSER GMBH 2004]
Table 2-10
Raw waste water and permeate quality [according to AGGERWASSER GMBH 2004]
Parameter Unit Raw waste water Permeate
COD [mg/L] 60 < 3
BOD5 [mg/L] 40 < 2
Ptot [mg/L] – n. n.
Ntot [mg/L] – < 1
filterable solids [mg/L] 140 – 180 n. n.
MF2.2.2.2
MF2.2.2.3
Membrane Technology in Municipal Waste Water Treatment 2
St. Peter ob Judenburg Waste Water Treatment
Plant, Austria
With the waste water treatment plant of the municipality
St. Peter ob Judenburg (1,500 PE), the first experiences
with membrane technology in the treatment of muni-
cipal waste water in Austria have been acquired. For cost
reasons, the waste water treatment plant was initially
planned and approved by the authorities as water treat-
ment lagoons. Although the lagoons had been dimen-
sioned rather large, the plant did not meet the treatment
capacity required by the Austrian Emission Ordinance
(Emissionsverordnung (EmV) 210/1996) “Limitation of
waste water emissions from waste water treatment plants
in settlement areas“.
Within the scope of a research project realized in 2001
and 2002, it could be demonstrated and implemented in
the following that the existing plant can meet the legal
standards without important constructional alterations
by using new aeration and mixing concepts combined
with immersed membrane filtration in the nitrification
tank (Table 2-11).
By installation of a wooden partition, the lagoon was
divided into an activation zone and a secondary settle-
ment zone. Both zones are connected by two overflows
in the partition. In the secondary settlement zone, the
activated sludge settles and is discharged by the sludge
hopper at the bottom. Culvert siphons lead to a pump
shaft with a submerged pump which recycles the activa-
ted sludge into the activation zone or withdraws it from
the system.
To obtain complete nitrification, a separate nitrification
tank made of reinforced concrete is installed downstream
of the lagoon. The existing components for the growth
of biomass have been removed and replaced by immersed
membrane modules from the company Mitsubishi. A
total membrane surface area of 945 m2 is installed in
9 cassettes. Since the completion of the research project
in 2002, the St. Peter ob Judenburg waste water treat-
ment plant has been operated successfully according to
the process concept presented above (Figure 2-48). Figure
2-49 shows the membrane modules and the lagoon.
115
feed
blowerinstallation
membrane stage
fine screen3 mm
grit chamber BB
recirculation
NK
settling pond 1receivingwater
Figure 2-48
Flow sheet of the St. Peter ob Judenburg waste water treatment plant [according to ENVICARE 2002]
Table 2-11
Influent and effluent concentrations of the waste water treatment plant
Parameter Unit Influent Effluent lagoon Permeate
COD [mg/L] 300 – 700 100 – 300 < 30
NH4-N [mg/L] 25 – 45 25 – 35 < 1.0
UF2.2.3
Membrane Technology in Municipal Waste Water Treatment2
Waste Water Treatment Plants in Germany with
Ultrafiltration Membranes
Nordkanal Waste Water Treatment Plant
When the expansion of the Nordkanal waste water treat-
ment plant became necessary, the original site had to be
given up due to the spatial development of the City of
Kaarst. A new plant had to be built at another site. The
Erftverband decided on the membrane bioreactor process
because positive experience had been acquired with this
process at the Rödingen waste water treatment plant. The
waste water treatment concept was developed in close
coordination with the Ministry for Environment and
Nature Conservation, Agriculture and Consumer protec-
tion (MUNLV) of the state North-Rhine Westphalia. Due
to its size, this plant represents new planning dimensions
and has demonstration character throughout Europe.
The plant is designed for a capacity of 80,000 PE and a
combined water flow of 1,881 m3/h. It was commissioned
in 2003. The demands on the effluent quality are com-
piled in Table 2-12.
116
Figure 2-49
St. Peter ob Judenburg waste water treatment plant [photos: ENVICARE],
left: membrane module, right: lagoon
Table 2-12
Minimum requirements and discharge consent of the Nordkanal waste water treatment plant
[ERFTVERBAND 2004]
Parameter Unit Minimum requirements Discharge consent
COD mg/L 90 90
BOD5 mg/L 20 20
NH4-N mg/L 10 10
Ntot mg/L 18 18
Ptot mg/L 2 2
UF2.2.3.1
Membrane Technology in Municipal Waste Water Treatment 2
117
At the site of the old waste water treatment plant, the
waste water is pretreated by a coarse screen and pumped
to the new Nordkanal plant, situated a distance of 2.5 km
away, where the waste water is mechanically pretreated
by two step screens (5 mm spacing) operated in parallel
and two aerated grit and grease traps also operated in
parallel. Then the waste water is treated by two rotary
screens operated in parallel with an aperture size of 0.5 mm
(Figure 2-50) to protect the membranes in the nitrifica-
tion stage. The emergency circuit of the rotary screens is
made safe by a fine screen with an aperture size of 1 mm,
so that the membranes are protected from the input of
coarse material into the activated sludge tank. Figure 2-51
shows the flow sheet of the Nordkanal waste water treat-
ment plant.
The activated sludge stage has four lines, each of which
consists of upstream denitrification tanks, a variable tank
zone for either denitrification or nitrification, and of the
nitrification tanks with immersed membrane modules,
flow
recirculation
rotaryscreen0,5 mm
emergencybypassscreen 1mm
rotaryscreen0,5 mm
blowerinstallation
feed
gritchamber
screen
step screen5 mm
nitrificationmembrane stage
step screen5 mm
gritchamber
denitri-fication
variable-zone
denitri-fication
variable-zone
denitri-fication
variable-zone
denitri-fication
variable-zone
Figure 2-51
Flow sheet of the Nordkanal waste water treatment plant [according to ERFTVERBAND 2004]
Figure 2-50
Rotary screen of the fine screen installation
Membrane Technology in Municipal Waste Water Treatment2
designed as activated sludge tanks with circulating flow.
The nitrification tanks are cased. The total volume of the
activated sludge tanks is 9,200 m3. The sludge is stabilized
aerobically. As a result of flow simulations, agitators and
baffles were integrated into the activated sludge tanks
with circulating flow.
The membrane installation has been realized with eight
lines and equipped with capillary membranes from the
company ZENON (ZW 500c). A total filter surface area of
approx. 85,000 m2 has been installed because the District
Government Düsseldorf demanded to provide a reserve
of 25 % for the membrane filtration. For external chemi-
cal cleaning, a separate cleaning chamber is available.
The investment for the new construction of the Nord-
kanal waste water treatment plant was 21.5 million euro.
Approx. 6.6 million euro of this amount had been taken
over by the federal state North-Rhine Westphalia.
Monheim Waste Water Treatment Plant
The waste water treatment plant of the city of Monheim
is situated in the sensitive karstland of the district Donau-
Ries. It treats not only the waste water from the city of
Monheim, but also from the municipalities of Rögling
and Tagmersheim. The treated effluent is discharged into
the Gailach which infiltrates into the karst 6 km down-
stream of Monheim. In 1998 and 1999, first concepts for
the discharge of waste water into the karst subsoil were
developed.
Within the scope of the large-scale pilot project “Waste
water treatment Gailach valley“, the Free State of Bavaria
supported the financing of the construction of a mem-
brane bioreactor at the site of the Monheim waste water
treatment plant. The investment for the membrane bio-
reactor was approx. 7.6 million euro, of which 5.8 mil-
lion euro were granted as subsidy by the state Bavaria.
Figure 2-53 shows the Monheim waste water treatment
plant.
The Monheim waste water treatment plant is designed for
a capacity of 9,700 PE, based on a peak flow of 288 m3/h
and an average daily waste water flow of 2,400 m3/d.
As shown in the flow sheet of the Monheim waste water
treatment plant (Figure 2-54), the mechanical pretreat-
ment stage has two lines. Each line consists of a fine sieve
with an aperture size of 1 mm and a grit chamber. 75 %
of the maximum inflow can be treated by each line. The
mechanically pretreated waste water flows into the acti-
vated sludge stage with a total volume of 1,660 m3, which
is also built in two lines. Each line consists of an upstream
denitrification and a nitrification tank as well as two
membrane chambers which have been provided with a
coating resistant to chemicals to protect the concrete.
The tanks for denitrification and nitrification have a
volume of 340 m3 each, while each of the four membrane
chambers has a volume of 75 m3. The sludge is stabilized
aerobically.
118
Figure 2-52
Membrane installation at the WWTP Nordkanal
UF2.2.3.2
Membrane Technology in Municipal Waste Water Treatment 2
The membrane stage was designed for a specific filtration
capacity of 22–24L/(m3·h) of combined flow. This volume
can be increased at short notice up to 31 L/(m3· h) when
one membrane chamber is shut down. According to this
design, the membrane stage contains 28 module cassettes
from the company ZENON (type ZW 500c) with a total
membrane surface area of 12,320 m2 filter. Filtration takes
place at a TS content of 12 g/L. Since the filtration lines
are installed in four separate chambers, chemical clean-
ing of the modules can be realized by pumping off the
activated sludge without removing the modules (on air).
The specific energy demand of the waste water treatment
plant is about 1 kWh per m3 of waste water. The man-
power requirement corresponds to that of a conventional
plant.
119
feed
membrane stage
gritchamber
denitrifi-cation
nitrifi-cation
flow
sieve 1 mm
sieve 1 mm
gritchamber
recirculation recirculation
recirculation recirculation
receivingwater
blowerinstallation
Figure 2-54
Flow sheet of the Monheim waste water treatment plant [according to BAYERISCHES LANDESAMT FÜR
WASSERWIRTSCHAFT 2004]
Figure 2-53
Monheim waste water treatment plant [photo:
BAYERISCHES LANDESAMT FÜR WASSERWIRTSCHAFT
(Bavarian Office for Water Management) 2004]
Membrane Technology in Municipal Waste Water Treatment2
Using the membrane process at the Monheim waste water
treatment plant, the requirements for the effluent quality
are safely met, as can be taken from Table 2-13.
At present, the operation of the Monheim membrane
bioreactor is accompanied by a research program. Main
items of this study include testing and optimization of
the membrane bioreactor process and investigating the
effects of waste water discharge on the Gailach and the
groundwater.
120
Figure 2-55
Module cassettes during in-air cleaning
[photo: CITY OF MONHEIM 2004]
Table 2-13
Minimum requirements, discharge consent and operating values of the Monheim waste water treatment
plant [BAYERISCHES LANDESAMT FÜR WASSERWIRTSCHAFT 2004]
Parameter Unit Minimum requirements Discharge consent Operating values
COD mg/L 90 75 15
BOD5 mg/L 20 15 1.2
NH4-N mg/L 10 5 0,1
Ntot mg/L – 18 10
Ptot mg/L – 1 0.6
Membrane Technology in Municipal Waste Water Treatment 2
Markranstädt Waste Water Treatment Plant
The Markranstädt waste water treatment plant is situated
in the southwest of Leipzig. It is one of more than 30
waste water treatment plants of Kommunale Wasserwerke
Leipzig (Municipal Waterworks). It was designed for
12,000 PE; the actual degree of capacity utilization is
approx. 8,000 PE.
The reason for a new construction of this plant was the
planned closure of the obsolete waste water treatment
plant which no longer complied with the requirements.
The deciding factors for the construction of a membrane
bioreactor were the limited surface area of the site and
increased demands on the effluent quality (Table 2-14)
due to a “weak” receiving water.
121
Table 2-14
Minimum requirements, discharge consent and operating values of the Markranstädt waste water
treatment plant [STEIN 2002a]
Parameter Unit Minimum requirements Discharge consent Operating values
COD [mg/L] 90 50 35
BOD5 [mg/L] 20 10 5
NH4-N [mg/L] 10 5 1
Ntot [mg/L] 18 18 15
Ptot [mg/L] 2 2 1
Filterable solids [mg/L] no information no set target no information
Figure 2-56
Process stages at the Markranstädt waste water treatment plant [STEIN 2002a],
left: inflow chamber to the membrane bioreactor with overflow edge to combined water treatment,
right: combined water treatment tank
UF2.2.3.3
Membrane Technology in Municipal Waste Water Treatment2
122
Figure 2-57
Process stages at the Markranstädt waste water treatment plant [STEIN 2002a],
left: step screen, right: nitrification and denitrification tanks
The plant has a hydraulic capacity of 180 m3/h. From the
intercepting sewer of the combined sewer system, the waste
water is fed by a lifting pump via the inflow chamber
(Figure 2-56, left) to the mechanical pretreatment stage.
The two-line mechanical pretreatment stage consists
of a step screen (3 mm spacing) (Figure 2-57, left) and a
grit and grease trap. By a distributor the waste water
flows into the two-line activated sludge stage. It is
operated as upstream denitrification (VDN = 2 · 435 m3)
with downstream nitrification (VN = 2 · 435 m3). All tanks
are equipped with agitators. In addition, aggregates for
fine-bubble aeration are installed over the whole surface
area of the bottom of the nitrification tanks.
The membrane modules for biomass separation from the
company ZENON are arranged at the inner longitudinal
sides in the upper zone of the nitrification tanks with a
depth of 7 m. The total filter surface area of 7,360 m2 is
distributed in four lines, two each in both nitrification
zones. Between the longwise arranged nitrification tanks
a cleaning shaft for external module cleaning is installed.
The modules can be removed by a fixed crane.
Besides the waste water treatment plant, a combined
water treatment plant was built in parallel at the same
site. The waste water quantities which exceed the capacity
of the membrane stage during combined water flow are
stored temporarily and pretreated in parallel in two tanks
which serve as settling and storage tanks. These waste
water quantities are fed to the membrane installation
during periods with smaller inflow volumes. Thanks to
the combined water treatment plant, the necessary mem-
brane surface area could be considerably reduced because
it had not to be designed for the maximum inflow quan-
tity, but only for 1.1 · Q T.
Since the plant was commissioned in 2000, much knowl-
edge has been acquired concerning the optimization of
process engineering and control [MEYER 2001]. Improve-
ment of mechanical pretreatment was especially impor-
tant. The screen installed initially was replaced by a com-
bination of coarse screen (5 mm spacing) and fine sieve
with an aperture size of < 1 mm.
Membrane Technology in Municipal Waste Water Treatment 2
Rödingen Waste Water Treatment Plant
The waste water treatment plant is situated in the territory
of the municipality of Titz in the district of Düren in the
immediate vicinity of the opencast mining Hambach. Its
catchment area comprises a predominantly rural region
with smaller villages which do not discharge commercial
or industrial waste water. Groundwater depletion due to
mining prevents the contact of the receiving water with
the groundwater so that in dry periods the water level of
the receiving water is very low. Therefore, an important
portion of the receiving water is supplied by the effluent
from the Rödingen waste water treatment plant. On
account of this fact, the district government sets high
standards for the discharge of waste water into this re-
ceiving water (see monitoring values in Table 2-15).
For this reason, a new construction of the Rödingen
waste water treatment plant, which up to now consisted
of an activated sludge stage with intermittent denitrifica-
tion and simultaneous precipitation for phosphorus
removal, was indispensable. Upgrading by conventional
technology would have required investments of approx.
6.1 million euro for the construction of large activated
sludge tanks and a downstream floc filtration.
The Erftverband, as the responsible water board, decided
on the construction of a membrane bioreactor because in
1996 first knowledge on the operating mode, the effluent
quality to be attained and operational liability was ac-
quired in the course of successful operation of a pilot plant
using this technology. One million euro of the total costs
of 2.8 million euro for the first large-scale installation in
Germany, which was put into operation in the middle of
1999, were taken over by the state North-Rhine Westphalia.
The installation is designed for a daily waste water flow
of 450 m3. With combined water flow, up to 135 m3 per
hour are treated.
The inflow to the plant is mechanically pretreated by a
fine screen with a spacing of 3 mm, followed by an aerated
grit chamber (Figure 2-58). The waste water is then fed to
the two bioreactors which are operated with intermittent
nitrification/denitrification.
When the mixed liquor has passed the biological stage,
it flows into the two-line filtration stage, from where
the treated water is withdrawn by immersed microfiltra-
tion modules. The concentrated mixed liquor remaining
in the filtration zone, which has a TS content higher by
4 g/L than in the rest of the activated sludge tank is pum-
ped back into the bioreactors.
Each of the two filtration lines (Figure 2-59) consists of
six cassettes each with 8 modules from the company
ZENON. The total membrane surface area is 4,846 m2. A
combined specific water flow of approx. 28 L/(m3·h) has
been calculated as design capacity for the membranes.
The background for this higher than typical design speci-
fic flow rate were measures waiting to be done in the
sewer system in order to reduce the infiltration water
123
Table 2-15
Minimum requirements and discharge consent of the Rödingen waste water treatment plant
[according to ENGELHARDT ET AL. 2001]
Parameter Unit Minimum requirements Discharge consent Operating values
COD mg/L 110 35 < 25
BOD5 mg/L 25 8 < 3
NH4-N (at 5 °C) mg/L – 2 < 0,5
Ptot mg/L – 0.5 < 0.3 (simultaneous precipitation)
AOX µg/L – 50 < 50
UF2.2.3.4
Membrane Technology in Municipal Waste Water Treatment2
rate. Therefore, smaller inflow volumes are expected with
resulting flow rates < 28 L(m3 · h).
To maintain the filtration capacity, the modules are not
only submitted to normal backwashing (300 – 500 sec. fil-
tration, 30 sec. backwashing) and weekly intermediate
cleaning, but also to intensive chemical cleaning twice a
year. For this purpose the modules are removed from the
filtration tank and cleaned chemically, from inside and
outside, in a separate heatable container. With this, the
permeability of the membranes, and possibly necessary
capacity reserves, are restored.
Within the scope of a research project promoted by the
state North-Rhine Westphalia, the operation of the first
German large-scale membrane bioreactor was accompa-
nied by scientists. The aim was to acquire more far-
reaching knowledge for new constructions of membrane
bioreactors, in particular about the operating mode of
124
V= 200m3 V= 200m3
nitrification andmembrane containerV=80m3
nitri-/denitrifi-cation tank 1
blowerstationmembranereactor
feed
nitri-/denitrifi-cation tank 2
grit and oilchamber
screen3 mm
membranefiltration
membranefiltration
RS
recirculation
blower stationnitrification
partial flowtreatment
fine sieve0,5 mm
permeate
Figure 2-58
Flow sheet of the Rödingen waste water treatment plant
Figure 2-59
View into the two filtration lines during fitting of
the ZeeWeedTM-cassettes [photo: ERFTVERBAND]
Membrane Technology in Municipal Waste Water Treatment 2
the membrane modules in order to reduce the energy
demand of module aeration. The following measures
have been realized successfully:
• single filtration lines are switched on or off depending
on the water volume to be filtered
• discontinuous aeration of the membrane modules
• intermittent operation of the activated sludge stage to
get small recirculation flows
Moreover, it turned out that the waste water needs better
mechanical pretreatment because accumulation and
sticking of fibrous material occurred on the hollow-fibre
membranes. For this reason, a partial flow of the activa-
ted sludge is treated by sieving between the activated
sludge tank and the filtration tank (see Figure 2-58) to
remove fibres and coarse material which get into the acti-
vated sludge stage despite mechanical pretreatment
[ENGELHARDT ET AL. 2001].
Schramberg-Waldmössingen Waste Water
Treatment Plant
The Schramberg-Waldmössingen waste water treatment
plant had been operated from 1995 to 1998 at the limit
of its capacity. The consent for operation was limited to
31st December 1998. Since the effluent is discharged into
the „weak“ and sensitive receiving water Heimbach (a
creek), discussions with the supervising authority had
determined in 1996 that the operation of a conventional
waste water treatment plant without a tertiary treatment
stage would no longer be approved at this site. Before
expanding the plant, several alternatives were studied,
including connection to and upgrading of neighbouring
waste water treatment plants. However, in 2001 it was
decided to expand the plant at the same site with the
membrane bioreactor process, because this was the most
ecologically and economically favourable solution.
The waste water treatment plant (Figure 2-60) is designed
for 2,600 PE and a waste water flow of up to 90 m3/h.
As presented in the flow sheet of the plant (Figure 2-61),
mechanical pretreatment is carried out by a screen (5 mm
spacing) and a grit chamber. Two slot sieves (0.5 mm spa-
cing) operated in parallel are arranged downstream of the
grit chamber to protect the membrane stage. The activa-
ted sludge stage comprises an upstream denitrification
tank (V = 250 m3), a nitrification tank (V = 480 m3) and
the membrane bioreactor.
The two-line membrane stage is equipped with 10 module
cassettes (type 500 c) from the company ZENON (see
Figure 2-62). The membrane surface area of approx.
4,400 m3 in total treats an average permeate flow of
2,160 m3/d.
The investment for the waste water treatment plant
amounted to 2.8 million euro. The state Baden-Württem-
berg prioritized this project and provided a subsidy of
34 % within the scope of the general promotion of waste
water treatment projects, so that the plant could be com-
missioned in 2004. For one year the University of Stutt-
gart assists with and documents the operation of the
plant and determines its treatment capacity.
125
Figure 2-60
Schramberg-Waldmössingen waste water treat-
ment plant [photo: STADTWERKE SCHRAMBERG
(municipal utilities) 2004]
UF2.2.3.5
Membrane Technology in Municipal Waste Water Treatment2
126
feed
receivingwater
fine screen0,5 mm
nitrification,membrane stage
fine screen0,5 mm
blowerinstallation
denitri-fication
nitri-fication
gritchamber
screen5 mm
recirculation
Figure 2-61
Flow sheet of the Schramberg-Waldmössingen waste water treatment plant [according to STADTWERKE
SCHRAMBERG 2004]
Figure 2-62
Membrane installation at the Schramberg-Waldmössingen waste water treatment plant [photos: STADT-
WERKE SCHRAMBERG 2004], left: view of the membrane tanks, right: membrane module
UF2.2.3.6
Membrane Technology in Municipal Waste Water Treatment 2
Knautnaundorf Waste Water Treatment Plant
The Knautnaundorf waste water treatment plant of Kom-
munale Wasserwerke Leipzig (Municipal Waterworks) is
the newest membrane bioreactor put into operation in
Germany. With a capacity of 900 PE (expandable up to
1,800 PE) and a peak inflow of 23 m3/h, it is the smallest
“large-scale” membrane installation for municipal waste
water treatment. Although no increased demands on
waste water treatment were made at this site, the mem-
brane bioreactor process came out on top in the tender
results against conventional solutions because of lower
investment requirements. An important feature of this
site is the fact that it is fed by a separate sewer system.
As such, it was possible to reduce the investment for the
membrane stage compared to plants working with a com-
bined sewer system [WALTHER 2001].
The process engineering is comparable to that of the
installations described above. The following special fea-
tures have to be mentioned:
• For the first time the immersed system from the com-
pany Martin Systems was used in the membrane stage
(see chapter 2.1.2, figure 2-11). With a membrane sur-
face area of 756 m2, the performance of a German-
developed membrane can be proven on technical scale.
• The mechanical pretreatment stage is equipped with a
two-stage screen. The finest screen with an aperture
size of 1 mm in the second stage will retain all unde-
sired matter from the filtration zone.
• The bottom of the nitrification tank is fully equipped
with aerators for the plate membranes to ensure opti-
mal oxygen input.
After successful start-up in October 2001 and start of
regular operation for several weeks, the plant had to be
shut down due to a non-authorized discharge (diesel oil)
in order to settle claims for damages. At present, state-
ments on the operational behaviour of the installation
cannot be made because the plant has only been return-
ed to operation in April 2002.
127
Membrane Technology in Municipal Waste Water Treatment2
128
feed
fine screen3 mm
grit andoil chamber
fine screen1 mm
biological reactor
sludge
clarifier
membrane stage
recirculation
receivingwater
blowerinstallation
nitri-fikation
denitri-fikation
Figure 2-63
Flow sheet of the Simmerath demonstration plant [according to WVER 2004]
Simmerath Pilot Plant
The Wasserverband Eifel-Rur (WVER) (water board) opera-
tes a waste water treatment plants in the low mountain
region of Eifel. Since the plants are situated in drinking
water catchment areas, more stringent demands on their
effluent quality are made. Low waste water temperatures
in winter and a large amount of sewer infiltration create
additional challenges for waste water treatment. At the
Simmerath site, the WVER operates a waste water treat-
ment plant for 15,000 PE. Table 2-16 shows the demands
on the effluent quality of the membrane bioreactor.
Starting from these boundary conditions, a membrane
bioreactor pilot project was started in 2003 at the Simme-
rath waste water treatment plant, which is operated by
WVER and designed for 15,000 PE. The project is pro-
moted by the Ministry for Environment and Nature
Conservation, Agriculture and Consumer Protection
(MUNLV) of the state North Rhine-Westphalia.
Within the scope of the pilot project, a membrane biore-
actor was installed in a separate building on the site of
the Simmerath waste water treatment plant. It is equip-
ped with immersed capillary membranes from the com-
pany PURON which are tested in technical scale under
real conditions (Figure 2-64). The membrane bioreactor is
designed for a capacity of 750 PE. It treats a partial flow
of the effluent from mechanical pretreatment (rotary
screen with an aperture size of 3 mm) of the Simmerath
waste water treatment plant. Without further presieving
this partial flow is fed into the membrane bioreactor,
which consists of an activated sludge tank with a volume
of 136 m3, which is divided into an upstream denitrifica-
Table 2-16
Discharge consent of the Simmerath waste water treatment plant [WVER 2004]
Parameter COD BOD5 NH4-N Ntot Ptot AOX
Discharge consent 40 mg/l 10 mg/l 3 mg/l 18 mg/l 0.8 mg/l 50 µg/l
UF2.2.3.7
Membrane Technology in Municipal Waste Water Treatment 2
Knowledge on the clogging behaviour as well as on the
problems with fibrous matter in membrane installations
was acquired. Different treatment concepts were tested
concerning their efficiencies. The treatment results of the
plant were documented and evaluated. It was discovered
that the denitrification process was influenced by the
O2 load recycled from the membrane chamber. This prob-
lem was solved by changing the process configuration.
At present, a second research period is active to test, among
other things, further developed membranes and to opti-
mize the integration of the membrane modules into the
process engineering of the waste water treatment plant.
129
tion stage with subsequent nitrification and the down-
stream membrane stage with a volume of 20 m3. The TS
content in the tanks is between 10 and 14 g/L.
The membrane stage consists of two module cassettes with
a filter surface area of 500 m2 each, which are immersed
and operated in two separate chambers. The sludge from
the membrane stage is recycled either into the denitrifi-
cation or the nitrification zone. The permeate of the mem-
brane stage is fed into the in-flow of the Simmerath plant.
Over the course of the test period, the membrane modul-
es and their operation were continuously optimized so
that the operation of the membrane installation clearly
improved. The operating values of the membrane bio-
reactor are listed in Table 2-17.
Figure 2-64
Membrane installation at the Simmerath waste water treatment plant [photos: PURON AG 2003],
left: denitrification and nitrification tanks with the hall for the membrane installation,
right: membrane cassette
Table 2-17
Operating values of the membrane bioreactor in Simmerath [WVER 2004]
Parameter COD BOD5 NH4-N Ntot Ptot AOX
Operating values < 30 mg/L no Information < 1 mg/L < 8 mg/L < 2 mg/L – µg/L
Membrane Technology in Municipal Waste Water Treatment2
St. Wendel Golf Course
For several months, the City of St. Wendel has operated
at the site of the local golf course a new waste water treat-
ment plant according to the membrane bioreactor pro-
cess, which is currently treating the sanitary waste water
of the golf course and the restaurant. At present the waste
water flow is approx. 3 m3/d. Next year the hotel belong-
ing to the golf course will be finished so that the load
of the waste water treatment plant will reach the design
capacity of approx. 150 PE. 15 m3 of waste water will
then be treated per day. Currently approx. 3 m3 of waste
water per day are treated in the new waste water treat-
ment plant. This volume will increase to 15 m3/d, when
reaching the design capacity. The waste water treated in
this plant is infiltrated at the golf course. It is also possi-
ble to use it for golf course irrigation.
The construction and operation of the membrane biore-
actor are supported financially within the scope of a re-
search project promoted by the Ministry of the Environ-
ment of the federal state Saarland. A special innovation
represent the ceramic plate membranes (molecular sepa-
ration size ~ 0.1 µm) from the company ItN Nanovation
which are used for the first time in Germany for munici-
pal waste water treatment. Within the scope of the rese-
arch project, the performance and the service life of the
ceramic membranes will be examined. Especially con-
130
waste water
biological reactormembrane stage infiltrationpermeate
storage
buffertank
fine screen3 mmfine screen
3mm
Figure 2-65
Flow sheet of the golf course St. Wendel waste water treatment plant [according to ST. WENDEL]
Table 2-18
Minimum requirements, discharge consent and operating values of the golf course St. Wendel waste
water treatment plant [CITY OF ST. WENDEL 2005]
Parameter Unit Minimum requirements Operating values
COD mg/L 150 18
BOD5 mg/L 40 < 4
Total number of Bakteria coli cfu/100 mL < 100
UF2.2.3.8
Membrane Technology in Municipal Waste Water Treatment 2
cerning the service life, it is expected that the ceramic
membranes have a clear advantage compared to polymeric
membranes.
The waste water treatment plant consists of a buffer tank
with a volume of 7 m3, a rotary screen with an aperture
size of 3 mm, an activated sludge stage with a volume of
approx. 20 m3 and a downstream permeate storage tank.
The waste water flows from the buffer tank and the rotary
screen into the activated sludge stage in which the im-
mersed membranes are installed. The membranes are
aerated from below by slotted tubes. Thus the air is not
only used to control the covering layer on the mem-
branes, but also for aeration of the activated sludge stage.
Since the tanks are completely intermixed, sludge recy-
cling can be spared. Due to the small waste water volume
flow, the TS content in the activated sludge stage current-
ly is about 4 g/L. The design capacity has been calculated
with a TS content of 12 g/L.
The membrane stage consists of a rack with three mod-
ules. Each module has a membrane surface area of 11 m2,
so that a total membrane surface area of 33 m2 is install-
ed. For capacity expansion, the stage will be upgraded by
more modules.
The operating and cleaning concept of the membrane
stage using immersed ceramic membranes can be compa-
red with that of immersed membrane systems on poly-
mer basis. But due to the more solid ceramic membranes,
it is possible, among other things, to use higher trans-
membrane pressure differences, higher pressure levels
during backwashing and higher concentrations of clea-
ning chemicals.
The investment of the plant was approx. 400.000 euro,
75 % of which were taken over by the federal state Saar-
land. Besides the costs for the membrane bioreactor it-
self, this sum of 400.000 euro comprises, among other
things, the costs for connection, an appropriate building
for the site and a sludge mineralization plant.
131
Figure 2-66
Module rack at the golf course St. Wendel waste water treatment plant,
left: top view, [photo: ItN NANOVATION], right: side view [photo: ABWASSERWERK ST. WENDEL]
Membrane Technology in Municipal Waste Water Treatment2
Glessen Waste Water Treatment Plant
(Planning Stage)
The design capacity of the Glessen waste water treatment
plant (Erftverband) is currently 5,000 PE. The effluent is
discharged into a receiving water which infiltrates into
the groundwater of a drinking water catchment zone.
Therefore, the demands on the effluent quality are higher
than the minimum requirements for waste water treat-
ment plants of this size category (see Table 2-19).
In order to comply in future, too, with the demands on
the effluent quality, the waste water treatment plant is
expanded using existing plant components. In this con-
nection a waste water treatment plant with a pressure
pipe in a distance of 4 km will be also connected, so that
the design capacity of the plant at the Glessen site after
132
feed
gritchamber
fine screen5-6 mm
nitri-ficationtank
denitri-ficationtank
membrane stage/nitrification
recirculation
blowerinstallation
receivingwater
0.5 mm
screeningsystem
0.5 mm
Figure 2-67
Flow sheet of the Glessen waste water treatment plant [according to ERFTVERBAND 2004]
Table 2-19
Demands on the effluent quality of the Glessen waste water treatment plant
[according to ERFTVERBAND 2004]
Parameter Unit Minimum requirements for Discharge consent
WWTP of size category 3
COD mg/l 90 30
BOD5 mg/l 20 6
NH4-N mg/l 10 1.5
Ptot mg/l – 0.6
UF2.2.3.9
Membrane Technology in Municipal Waste Water Treatment 2
expansion will be 9,000 PE. With dry weather flow, the
daily waste water quantity is 2,394 m3.
The Glessen waste water treatment plant is in the plan-
ning stage. The concept (Figure 2-67) provides mechanical
pretreatment by a single-line screen with a spacing of
6 mm. The grit chamber, with a volume of 53 m3, is
planned with a single line, followed by the two-line fine
screen with a spacing of 0.5mm. The membrane bioreactor
will be operated with simultaneous denitrification and
aerobic sludge stabilization. The activated sludge tank with
Installations Outside of Germany with
Ultrafiltration Membranes
The largest membrane bioreactor in the world up to the
year 2004, and one of the most modern plants in Eng-
land, is the Lowestoft waste water treatment plant which
was put into operation in the beginning of 2002 with a
capacity of 46,000 PE (only for the membrane bioreactor)
(Figure 2-68). For this plant as well as for the Campbeltwon
waste water treatment plant (Scotland, 6,000 – 9,000 PE),
the ZenoGemTM system is used.
circulating flow for nitrification and denitrification has a
total volume of 1,680 m3.
Planning is based on membranes from the company
ZENON installed in four tanks with 7 modules each of the
type 500 c and a total membrane surface area of 12,320 m3.
The TS content will be 12 g/L. The membrane installation
was designed for a specific filtration capacity of 22 L/(m2 ·h),
which will have to be increased to approx. 30 L/(m2· h)
in case a membrane line has to be shut down on short
notice. The former secondary settling tank with a volume
of 560 m3 will be used as an equalization tank.
133
inflow
inletstructure
distributor lamellaseparator
membrane bioreactor 1
membrane bioreactor 2 permeatestorage tank
backflush pumps
to inletstructure
vacuum pumps
distributor
ZeeWeedTM
ZeeWeedTM
Figure 2-68
Aerial photograph and flow sheet of the Lowestoft waste water treatment plant [ZENON 2002]
UF2.2.4
UF2.2.4.1
Membrane Technology in Municipal Waste Water Treatment2
Pilot Plants at the Beverwijk Waste Water
Treatment Plant, The Netherlands
From 2000 to 2004, the consulting engineers DHV and
the Stichting Toegepast Onderzoek Waterbeheer (Stowa)
have realized at the Beverwijk waste water treatment plant
(capacity: 450,000 PE) the decisive research project con-
cerning the membrane bioreactor process in The Nether-
lands. Over the course of these four years, various module
systems (ZENON, Kubota, X-Flow, Mitsubishi, Memfis,
The research project at the Beverwijk waste water treat-
ment plant has been successfully completed [VAN DER
ROEST ET AL. 2002]. The large-scale plant at Varssefeld
has been planned and built on the basis of the results
from Beverwijk.
Toray and Huber) have been tested with a view to their
capacity and suitability in practice.
The tests have been carried out on a test field built espe-
cially for this purpose with separate membrane bioreac-
tors. The overview in Table 2-20 shows the important key
features of the individual test installations.
134
Table 2-20
Key features of the individual pilot installations [DHV 2004]
Manufacturer
Huber
Kubota
Memfis
Mitsubishi
Toray
X-Flow
ZENON
ZENON
ZENON
Type
plate
plate
plate
hollow fibre
plate
tubular
hollow fibre
(module ZW 500a)
hollow fibre
(module ZW 500c)
hollow fibre
(module ZW 500d)
Pore size
[µm]
0.038
0.4
0.05
0.4
0.08
0.03
0.035
0.035
0.035
Membrane surface
[m2]
360
240
112
314
137
220
184
55
90
Permeate flow
[m3/h]
15
10
5
7
5
9
8
3
5
Test period
10/03 – 07/04
05/00 – 07/02
05/02 – 06/03
05/00 – 03/02
02/03 – 02/04
05/00 – 04/02
03/00 – 10/02
03/01 – 03/03
11/02 – 08/03
Membrane Technology in Municipal Waste Water Treatment 2
135
Figure 2-69
Photos of the pilot installations and membrane modules at the test field of the Beverwijk waste water
treatment plant [DHV 2004]
From left to right: Huber, Huber
From left to right: Kubota, Kubota, Mitsubishi, Mitsubishi
From left to right: X-Flow, X-Flow, Zenon, Zenon
From left to right: Memfis, Memfis, Toray, Toray
UF2.2.4.2
Membrane Technology in Municipal Waste Water Treatment2
Varsseveld Waste Water Treatment Plant,
The Netherlands
The membrane bioreactor at the Varsseveld waste water
treatment plant is the first large-scale implementation of
this process in The Netherlands. It will be put into opera-
tion in the beginning of 2005. Since April 2004, a pilot
plant has been operated within the scope of a research
project at the site of the Varsseveld waste water treatment
plant with a permeate flow of 3.5 m3/h to study process
optimizations for the large-scale plant. In parallel, the
large-scale plant has been built. The project is realized and
assisted by the water board Rijn en IJssel, the Stowa, DHV
and other institutions. The research project is financed
by the Stowa and the EU LIFE program (see also possibili-
ties for promotion by EU in the annex).
The connection size of the Varsseveld waste water treat-
ment plant is 23,150 PE with a maximum waste water
volume flow of 755 m3/h. Waste water treatment plants
in The Netherlands are faced with a hydraulic load in the
case of stormwater flow which is greater by a factor three
compared to the average waste water load. This is also
true for the Varsseveld waste water treatment plant. An
average daily waste water volume of 5,000 m3/d was de-
termined. The supervisory authorities demand effluent
concentrations of < 5 mg/L for nitrogen and < 0.15 mg/L
for phosphorus.
The membrane installation was built with four trains
(Figure 2-70). A total membrane surface area of 20,160 m2
of the company ZENON (module type: ZW 500 d) has
been installed. The calculated specific stormwater flow is
37.5 L/(m3 · h) of permeate. The membrane installation
can be increased with additional modules, if necessary.
The investment for the Varsseveld waste water treatment
plant amounts to 10 million euro.
136
feed
recirculation
gritchamber
circulation tank with aerated zoneand upstream denitrification
fine screen6 mm
outlet
fine screen0,8 mm
membrane stage
Figure 2-70
Flow sheet of the Varsseveld waste water treatment plant [according to DHV 2004]
UF2.2.4.3
Membrane Technology in Municipal Waste Water Treatment 2
Brescia Waste Water Treatment Plant, Italy
The Brescia waste water treatment plant is an example for
the advantage of the membrane bioreactor process in the
case of necessary plant expansion at limited space available.
Since 1980, the Brescia waste water treatment plant existed
as three-line activated sludge plant. Each of the three
lines consisted of primary clarification, activated sludge
tank, secondary clarification and dosing station for chlo-
rine. Due to more stringent demands on the Ntot effluent
concentration (< 15 mg/L), the waste water treatment
plant had to be expanded in 2000. Upgrading the con-
ventional activated sludge process would have required
the construction of very large tank volumes for a denitri-
fication system which was not possible with the space
available. With the membrane bioreactor process, a plant
expansion has been achieved with alteration of only one
treatment line (Figure 2-71).
The secondary clarification tank was replaced by a four-
line membrane stage. 160 membrane cassettes of the type
500C (capillary membranes) from the company ZENON
with a total surface area of 70,400 m2 are installed. 50 %
of the waste water volume flow of the Brescia waste water
treatment plant (about 40,000 m3/d) is treated by the
137
membrane stage
clarifier
recirculation
sludge
flow
feed
primary treatment
fine screen3 mm
gritchamber
fine screen3 mm
gritchamber
primary treatment
nitrifi-cation
denitrifi-cation
nitrifi-cation
denitrifi-cation
recirculation
sludge
recirculation
nitrifi-cation
denitrifi-cation
clarifier
recirculation
receivingwater
existing plant expansion
Figure 2-71
Flow sheet of the Brescia waste water treatment plant [according to ZENON GMBH 2004]
Membrane Technology in Municipal Waste Water Treatment2
membrane bioreactor line. The remaining 50 % are treat-
ed by the two conventional lines. Today the Brescia
waste water treatment plant has a treatment capacity of
approx. 150,000 PE. Figure 2-72 shows an aerial photo-
graph of the Brescia waste water treatment plant.
Thanks to the conversion finished in 2002, the effluent
values of the plant improved considerably. The raw waste
water concentration for some parameters, the operating
values of the plant and the demands on the effluent qua-
lity are listed in Table 2-21.
138
Figure 2-72
Aerial photograph of the Brescia waste water treatment plant [photo: ZENON GMBH 2004]
Table 2-21
Raw waste water concentration, operating values and requirements of the Brescia waste water treatment
plant [ZENON GMBH 2004]
Parameter Unit Raw waste water Operating values Requirements
concentration
COD mg/L 505 20 < 125
BOD5 mg/L 255 10 < 25
TS mg/L 290 not detectable 2
TKN mg/L 50 2 < 15 (Ntot)
Turbidity mg/L >50 < 10 no data
Membrane Technology in Municipal Waste Water Treatment 2
Säntis Waste Water Treatment Plant, Switzerland
On the peak of the Säntis, a top station with restaurant
and telecommunication centre is situated. To purify waste
water and to treat waste water for non-potable drinking
water purposes, the existing small waste water treatment
plant was replaced in 2000 by membrane technology
according to the ZenoGemTM process. The installation is
operated by Swisscom and Säntis-Schwebebahn AG
(Funicular AG).
Thanks to the compact structure of the membrane tech-
nology, the installation could be integrated into the exist-
ing building with very restricted space. It distinguishes
itself by high cleaning efficiency (effluent values: COD
< 30 mg/L, NH4-N < 2 mg/L) at extreme temperatures and
a high inflow dynamics due to rapid load changes at up
to 8,000 visitors per day.
139
kitchen waste water
sludge storagesettlement
grease separator sieve screw
buffer tanks
other inflow
permeatetank
disinfectionrailtransportation
nitrificationwith ZeeWeedTM
denitrification
effluent
Figure 2-73
View and flow sheet of the membrane bioreactor according to the ZenoGemTM process on the Säntis
[ZENON 2002], situation of the membrane bioreactor on the Säntis and view of the modules [ZENON 2002]
UF2.2.4.4
MF2.3.1
Membrane Technology in Municipal Waste Water Treatment2
2.3
Small Waste Water Treatment Plants, Mobile
Installations and Ships Waste Water Treatment
with Membrane Technology
Small or domestic waste water treatment plants are used
in Germany as long-term solution depending on the regula-
tions of the water legislation of the individual states. In
North-Rhine Westphalia, § 53 section 4 Landeswassergesetz
(law on water) is decisive. According to this article, private
property-related waste water treatment is permissible only
for properties outside of coherently built-up areas.
According to an assessment by OTTO [2002], until the
year 2006 up to 4 million German citizens will remain
unconnected to a central sewer system and therefore are
responsible themselves for waste water disposal. In North-
Rhine Westphalia, at present about 580,000 inhabitants
are not connected to central sewer systems or waste water
treatment plants. They treat their waste water by approx.
130,000 small waste water treatment plants and cesspits
without outlet [MUNLV 2005].
With further technical development, membrane filtration
is becoming more and more accepted in the field of small
waste water treatment plants.
With membrane technology, small waste water treatment
plants are able to attain higher cleaning efficiencies at
high operational safety (Table 2-22). Besides ultrafiltra-
tion of the treated waste water, the operator can also use
the treated water as non-potable water for domestic pur-
poses, e.g. for toilet flushing or garden irrigation. In addi-
tion to ecological advantages, cost savings by reducing
the drinking water demand for non-potable water appli-
cations may be decisive to use this process concept.
In the meantime, several manufacturers offer or are devel-
oping corresponding systems. At present, the inhabitant-
related investments are between 1,000 and 1,500 euro
per inhabitant, depending on the size of the installation.
In addition, costs of 60 – 110 euro per inhabitant per year
arise for operation and maintenance.
In the following sections, the most fully developed systems
are presented which include numerous references.
Busse-MF Installation from the Company Busse
The company Busse Innovative Systeme GmbH produces
and sells an installation with membrane technology
which is the first small or domestic waste water treatment
plant with type approval (Z-55.3-60) by Deutsches Insti-
tut für Bautechnik (DIBt) (German Institute for Construc-
tion Engineering).
The production started in autumn 1999. In the meantime,
more than 250 installations (as of 2005) are operated
with this technology worldwide with connection capaci-
ties from 2 to 32 PE. They are used for the treatment of
waste water from detached houses and multiple dwelling
units, office buildings, restaurants and hotels in Germany
and 10 more countries [BUSSE 2005]. By using membra-
nes, the Busse-MF system is very compact, as can be seen
in Figure 2-74, which is typical for a Busse-MF installa-
tion fitted in the cellar of a residential building.
As shown by the flow sheet in Figure 2-75, the system
consists of two tanks. The first tank (primary settling) is
connected directly to the downpipe for waste water trans-
portation. It serves to separate coarse matter and to store
waste water and sludge temporarily. From the central
140
Figure 2-74
View of the Busse MF small waste water treatment
plant (formerly BioMIRTM) [BUSSE 2002]
Membrane Technology in Municipal Waste Water Treatment 2
tank zone, the liquid phase is pumped by a mammoth
pump, which is protected by a plastic network, into the
second tank (activated sludge tank) where biological
waste water treatment and phase separation take place
using immersed plate modules from the company Kubota.
The transmembrane pressure difference necessary for per-
meate discharge is generated by the hydrostatic pressure
of the water head between the permeate outlet and filling
level of the activated sludge tank. Thus there is no need
for a suction pump to withdraw the permeate.
The plant is usually installed in the cellar or the garage.
It is also possible to use an existing pit as an upstream
waste water storage tank and coarse matter separator. In
this case, only the downstream activated sludge stage has
to be upgraded with membrane filtration.
The treatment capacity is sufficient to meet the de-
mands according to the approval principles for small waste
water treatment plants of DIBt [N.N. 2002d], as was alrea-
dy proven by independent studies [ROSENWINKEL ET
AL. 2001; KRAUME ET AL. 2000]. Table 2-22 shows a
comparison of the limit values according to DIBt [N.N.
2002d] and the mean values of qualified random samples
and 24-h-composite samples taken each month over a
one-year test period [ROSENWINKEL ET AL. 2001]. It can
be seen that the effluent values remain below the stand-
ard values.
141
waste water frombathroom, kitchen,toilet
ventilation byexisting shaft
condenser
mammouth pumpwith coarse-matterseparator
intermediate storage ofwaste water and sludge
activated sludge stagewith filtration unit
permeate
Figure 2-75
Flow sheet of a Busse-MF installation [BUSSE 2002]
Table 2-22
Requirements for the effluent quality of small waste water treatment plants and measured effluent values
of the Busse-MF installation
Parameter Unit Minimum requirements Limit values according Effluent values
to DIBt 2000 for installations Busse-MF installation
with nitrification [N.N. 2002d] [ROSENWINKEL ET AL. 2001]
COD mg/L 150 90 39
BOD5 mg/L 40 20 2.4 *
NH4-N mg/L – 10 (at > 12 °C) 4.5
Filterable solids mg/L – 50 0.65 *
* higher effluent values are due to algae growth in the filtrate collecting tank
MF2.3.2
Membrane Technology in Municipal Waste Water Treatment2
UltraSept Installation from the Company Mall
Another system is the UltraSept installation marketed by
the company Mall GmbH (Figure 2-76). More than 50 of
these plants with a size of 6 to 40 connected inhabitants
are operated in Germany.
The installation consists of three compartments arranged
according to the principle of a three-compartment septic
tank. The first two compartments are used for the pretreat-
ment of the waste water according to the principle of a
multicompartment septic tank. The third compartment is
the largest. It contains the activated sludge stage and the
filtration unit for the discharge of the treated waste water.
For a membrane module, a module from the company
Weise is used.
The installation is usually lowered completely into a pit
excavated for this purpose. In case a multicompartment
septic tank already exists, it is possible to upgrade the
existing tank with membrane technology to improve the
effluent quality. This alternative is less expensive than a
new installation.
142
feed
emergency
overflow
Mall UltraSeptapplied for national technical approval
connection for outlet, aeration, control lead
mechanical stage
rubber seal (elastomer gasket)
biological stage
float switch
suction duct
aeration lead
membrane module (physical stage)
Figure 2-76
Schematic representation of the UltraSept installation from the company Mall [MALL 2002]
MF2.3.3
Membrane Technology in Municipal Waste Water Treatment 2
Small Waste Water Treatment Plant for 4 PE
in North-Rhine Westphalia
Within the scope of a pilot project for decentralized waste
water treatment and treatment of non-potable water for
domestic purposes, a small waste water treatment plant
according to the UltraSept process is operated in the nor-
thern Eifel (low mountain region in North Rhine-West-
phalia). The plant is installed at the part-time cattle breed-
ing farm of a four-member family.
The membrane bioreactor has a nominal capacity of
900 L/d and is fed with an actual waste water volume of
900 L/d. In addition to the waste water treatment plant,
two storage tanks for further utilization of the treated
waste water have been installed which buffer the differ-
ences between the production of and the demand for
non-potable water for domestic purposes.
Kreditanstalt für Wiederaufbau (KfW),
Service Water Treatment
At the Kreditanstalt für Wiederaufbau in Frankfurt (KfW),
a combination of a fixed-bed activated sludge stage and a
membrane stage is used for the treatment of grey water
in such a way that it can be reused as service water. The
grey water is composed of the shower water from the
employees’ apartments and the waste water from the tea-
houses and the kitchen of the board of management.
At first, the kitchen waste water is pretreated by a grease
trap, and hairs etc. are removed mechanically from the
shower waste water (Figure 2-77). Both pretreated waste
water flows are fed into an activated sludge stage.
The biological stage is realized as fixed-bed activated
sludge stage with special components for biomass growth
A small tank with a volume of 0.6 m3 is used to cover the
demand for non-potable water in the house. The tank is
installed below ground to prevent the new formation of
germs in the water during storage. The connections to the
domestic piping are realized according to the technical
principles of rainwater utilization.
The non-potable water which is not needed directly in
the house, is stored in a long-term storage tank which, in
the case of this pilot project, is constructed as a foil pond
with a volume of 36 m3. The water stored there is used to
clean the cow-sheds and to irrigate the garden [KLEMENS
2002].
143
shower waste water
processwaterstorage
ultrafiltration
kitchen waste water
sieve
greaseseparator
fixed bedactivation
toilets
buffertank
storage
Figure 2-77
Grey water treatment plant at KfW
UF2.3.4
Small Waste Water Treatment Plant Membrane
ClearBoxTM and Huber HoneyCombTM from the
Company Huber AG
The company Hans Huber AG markets the small waste
water treatment plant MembraneClearBoxTM and the
HoneyCombTM system, which are used in particular for
decentralized waste water treatment in rural areas. Both
systems can be installed as expansion kits in existing or
new multicompartment septic tanks (Figure 2-79). The
process consists of the three steps pre-treatment, activa-
tion and membrane filtration. The MembraneClearBoxTM
(MCB) can be used for up to 8 PE and the HoneyCombTM
system for 9 – 150 PE.
The first compartment serves for primary treatment and
the second serves for primary treatment or as buffer tank,
before the waste water is fed in free over-flow into the
third compartment, which is built as an activated sludge
tank. The assembly kit and an aeration system are install-
ed in this tank. Depending on the size of the plant, the
assembly kit consists of a varying number of plate mod-
Membrane Technology in Municipal Waste Water Treatment2
developed by the company ACO Passavant. After having
passed this stage, the waste water is fed into a storage
tank and then filtered by an ultrafiltration installation, a
MicroClear plant from the company Weise Water Systems
GmbH (Figure 2-78). The installation is equipped with
immersed plate modules with a total membrane surface
area of 44 m2. An average permeate volume of 500 L is
filtered per hour by the membrane stage. Compared to
other membrane bioreactors with suspended biomass, this
plant receives waste water with rather low TS content,
formed only by the sludge output from the components
for biomass growth. Therefore, the plate membrane mod-
ules have relatively small spacings between the plates of
2.5 mm.
The treated water is fed into a storage tank. As service
water it is used among other things for toilet flushing in
the administration building and in the apartments of the
employees.
ules, the so-called VUM modules (VacuumUpstream
Membrane), which are equipped with ultrafiltration mem-
branes. The clear water withdrawn by a vacuum pump
can either be used as non-potable domestic water, dis-
charged or infiltrated. The related aggregate and control
unit (Figure 2-80) can be installed close to the septic tank
in a heated control cabinet or in the cellar of the neigh-
bouring residential building. The MCB plants are equipped
with a remote control, which in case of a breakdown sends
an information via SMS, e-mail or fax.
According to information from the manufacturer, the
operation of existing small waste water treatment plants
has shown that the COD can be reduced by more than
95 % and ammonia nitrogen by approx. 98 %. The energy
consumption for a 4-PE plant is about 2 kWh/d. In some
plants, the excess sludge production has clearly decreased,
e.g. in one plant from initially approx. 0.09 kg TS/(m3 · d)
to only 0.015 kg TS/(m3 · d) after a longer operation period.
Even after more than one year of operation, excess sludge
removal was not necessary.
144
Figure 2-78
Membrane installation for the treatment of service
water in the cellar of KfW [WEISE WATER SYSTEMS
GMBH]
UF2.3.5
Membrane Technology in Municipal Waste Water Treatment 2
145
1. settling tank with overflowfor coarse desludging
2. settling tankwith overflow
emergencyoverflow
aeration 3. activated sludge tankmembrane filtration
permeate discharge
inflow
1. settling tank with overflowfor coarse desludging
inflow
2. settling tankwith overflow
3. activated sludge tank
membrane filtration
aeration
Figure 2-79
Plot plan of a small waste water treatment plant with membrane technology installed in a multicompart-
ment septic tank [HUBER AG 2004]
Figure 2-80
Small waste water treatment plant MembraneClearBoxTM from Huber AG [photos: HUBER AG 2004],
left: aggregate and control unit, right: MCB expansion kit, consisting of plate module and aerator
MF2.3.6
Membrane Technology in Municipal Waste Water Treatment2
Mobile Installations for the Use in Military Camps
Missions of the German Armed Forces take place at various
locations in Germany and abroad for limited periods of
time. As such, long-term planning is often impossible. In
most cases, local infrastructure cannot be used so that
water supply and waste water disposal structures have to
be mobile, easy to handle and usable all over the world.
Moreover, they have to comply with the legal prescrip-
tions and the requirements of the troops employed.
On account of these requirements, the Bundesamt für
Wehrtechnik und Beschaffung (Federal Office for Defence
Technology and Provision), Koblenz, has charged A3
Abfall-Abwasser-Anlagentechnik GmbH (process techno-
logy for waste and waste water), Gelsenkirchen, to design
and build a mobile waste water treatment plant which is
fitted into a 20-inch container (see Figure 2-81). The plant
is able to treat the waste water of 300 soldiers at ambient
temperatures between -32 °C and +49 °C to such an ex-
tent that it can be discharged or infiltrated in place. Thanks
to the containerized construction, the plant can be used
at any time and in any location worldwide and transport-
ed by nearly any means of transportation (Figure 2-81).
The waste water to be treated is pumped via a grinding
unit to the container. Feeding from outside takes place by
automatically heated and isolated tubes to ensure opera-
tion of the plant in cold areas. The membrane bioreactor
fitted into the container includes six immersed plate mem-
brane modules from the company A3 GmbH with a total
membrane surface area of 120 m2. The filtrate is withdrawn
by a frequency-controlled suction pump and pumped to
the discharge point. A plant of this construction type has
been running since the beginning of 2004.
146
Figure 2-81
Transportation of the container plant by an emergency vehicle and schematic representation of the plant
[A3 GMBH 2004]
MF2.3.7
Membrane Technology in Municipal Waste Water Treatment 2
Ships’ Waste Water Treatment Plants with
Membrane Technology
Waste water discharge from ships used for civilian or mili-
tary purposes is regulated by national and international
law. The governing body responsible for international
legislation is the International Maritime Organization
(IMO). The discharge of ships’ waste water is regulated in
Annex IV of the IMO rules and standards (MARPOL 73/78).
As defined in these standards, the direct discharge of
waste water is not permitted, unless it has been treated
and disinfected by an officially approved installation.
Annex IV has been put into force in September 2003, after
the necessary conditions had been fulfilled in 2002 (trans-
fer into national legislation by a sufficient large number
of countries).
For inland navigation ships, the regulation concerning the
discharge of waste water will change with Article 9.01 of
the Agreement on Collection, Handing over and Accept-
ance of Waste in Rhine and Inland Navigation of the
Zentralkommission für die Rheinschifffahrt (Central Com-
mission for Rhine Navigation) [ZKR 2000]. According to
this article, the discharge of domestic waste water will
not be permitted from 1st January 2005 for cabin ships
with more than 50 sleeping places and from 1st January
2010 for passenger ships which are licensed for the trans-
portation of more than 50 passengers. The contracting
countries therefore commit themselves to establish ade-
quate receiving stations until the dates defined above.
The prohibition of waste water discharge is not valid for
passenger ships which are equipped with a licensed ship’s
waste water treatment plant. This agreement has not yet
come into force (as of August 2005) because it has not yet
been ratified by each single member state.
Up to now, grey water (waste water from showers, hand
basins, floor inlets) and kitchen waste water has histori-
cally been fed directly (without biological pretreatment)
into the disinfection cell of the waste water treatment
plant. For biological treatment of black water (waste
water from toilets) on ocean ships, at present activated
sludge plants, often arranged as cascades, are used for
preliminary treatment prior to disinfection.
The waste water is usually fed to the conventional plants
in surges, depending on the moment of waste water pro-
duction. The waste water flows into the first aerated acti-
vation chamber. After a reaction time which results from
the plantspecific hydraulics, it flows as mixed liquor into
the second activation chamber. It is aerated again to en-
sure further degradation of the organic waste water pollu-
tants. The waste water is then fed to the secondary sett-
ling tank and finally to the disinfection cell.
The process technology described above has some weak
points in particular for the application on board of ships
because it has been directly copied from conventional
municipal waste water treatment. The specific boundary
conditions on ships were often neglected. Special prob-
lems occur in secondary settlement because sedimenta-
tion is considerably disturbed by the movement of the
ship and continuous low-frequency vibrations resulting
from the ship’s engines. The result is regular occurences
of sludge being discharged from the secondary settling
tank into the sea. Also, the development of organic halo-
genated compounds during the disinfection of the efflu-
ent by means of chlorine bleach liquor is another critical
issue related to water pollution.
Since enclosed space on board of ships is extremely expen-
sive, all systems to be installed – including waste water
treatment plants – must be as small as possible.
The use of installations with microfiltration membranes
for waste water treatment has been successfully tested by
some projects [BRÜSS, RICHTER 2001]. Figure 2-82 shows
an example of such a plant. Waste water treatment plants
with membrane technology have the advantage that the
activated sludge plant can be operated at a dry matter
content TS BB of up to 20 g/L so that the aeration tank
volume can be reduced to a quarter compared to a con-
ventional plant. Also, by using microfiltration in the bio-
logical reactor, it is no longer necessary to provide a secon-
dary settlement zone. Separation of the activated sludge
is ensured by the membranes independent of the settling
characteristics of the mixed liquor. In addition, the efflu-
ent quality is clearly better, and chlorination of the waste
water for disinfection becomes unnecessary because of
germ retention.
147
UF2.3.8
Membrane Technology in Municipal Waste Water Treatment2
Cruise Liner Queen Mary 2
With a length of 325 m, a capacity of 2,620 passengers
and a crew of 1,250 persons, the Queen Mary 2 is one of
the biggest passenger cruisers in the world. Figure 2-84
shows a photo of the passenger cruiser Queen Mary 2.
In the hold of Queen Mary 2, the grey and black waters
are treated by a membrane bioreactor according to the
current state of technology. Decisive factors for the choice
of this installation were its compact construction and
high treatment capacity with the possibility to reuse or
to discharge the treated waste water. Thus the ship is
allowed to navigate in protected waters.
The daily waste water flow to be treated is approx. 1,100 m3.
After mechanical pretreatment by a hydrocyclone and a
fine screen with an opening size of 1 mm, the waste water
is fed into the activated sludge stage, which consists of
two tanks for denitrification and nitrification with a volu-
me of 150 m3 each. Solid-liquid separation takes place in
cross-flow operation mode in an ultrafiltration installa-
tion. The total membrane surface area, consisting of two
modules with plate membranes (PleiadeTM) from the com-
pany Rhodia (see Figure 2-83), is 700 m2. The permeate
Waste water treatment with membrane technology for
inland passenger ships, which must be adapted to the
boundary conditions of shipbuilding and operation, is
being studied at present within the scope of a projects
promoted by the Ministry for Environment and Nature
Conservation, Agriculture and Consumer Protection of
the federal state North Rhine-Westphalia (MUNLV NRW).
After successful tests with pilot plants (in the years 2002
–2004), the operation of a large-scale membrane bioreactor
will be studied on board of the event ship RheinEnergie
of Köln-Düsseldorfer Deutsche Rheinschifffahrt AG.
148
Figure 2-82
View of a MEMROD1) ship’s waste water treatment
plant according to the membrane bioreactor pro-
cess for 250 persons [VA TECH WABAG 2002]
Figure 2-83
Ultrafiltration module PleiadeTM for waste water
treatment on Queen Mary 2 [photo: ORELIS SA 2004]
1) MEMbrane Reactor Operation Device
Membrane Technology in Municipal Waste Water Treatment 2
volume flow is approx. 50 m3/h. For further reduction of
organic matter and for disinfection, an activated carbon
filter and a UV installation are installed downstream of the
ultrafiltration system. It is planned to reuse about 50 % of
the waste water treated by this process combination as
non-potable water on the cruise liner.
149
Figure 2-84
Photo of the Queen Mary 2
feed
hydrocyclone
membrane system
fine filter1 mm
150 m3 UV-disinfection
sludge
activatedcarbon
150 m3
biological reactor
recirculation
sludge
outlet
Figure 2-85
Flow sheet of the waste water treatment plan of Queen Mary 2 [according to ORELIS SA 2004]
UF RO2.3.9
Membrane Technology in Municipal Waste Water Treatment2
Grey and Black Water Treatment on Ships
The concept for waste water treatment used today on ships
is the one-stream solution which consists of mixing grey
water (from showers, handbasins, laundry) and black water
(from toilets) and combined treatment by membrane bio-
reactors. Immersed membrane modules, which are also
used in municipal waste water treatment, are applied.
Ultrafiltration installations with externally arranged mo-
dules with open channels at the raw-water side have also
been designed.
For large waste water volumes, e.g. on cruise liners with
more than 1,000 passengers, the two-stream solution can
be more effective. The grey water is treated by low-pres-
sure reverse osmosis membranes. The permeate is availa-
ble for technical purposes. The black water, the concen-
trate from low-pressure reverse osmosis and the kitchen
waste water are treated by a membrane bioreactor. The
filtrate can be discharged or reused in applications with
lower quality demands. The development of the two-
stream solution was influenced by knowledge and ex-
periences from the treatment of industrial waste water
by membrane processes and the “do-not-mix rule“. The
“do-not-mix rule” says that, in general, it is easier and
more efficient to treat waste water with different compo-
sition and clear concentration differences by different
processes. Figure 2-86 shows the two-stream solution
which has been implemented on 25 ships.
The membrane technology from the company Rochem
UF, presented by way of example, is based on ultra-
filtration and ultrafiltration + low-pressure reverse
osmosis. It is shown in Figure 2-87.
150
grey water
process water
blowerinstallation
ultrafiltration
black water
reverse osmosis
membrane bioreactor
discharge/sullage
blowerinstallation
Figure 2-86
Flow sheet of waste water treatment according to the two-stream solution [according to ROCHEM UF 2004]
Membrane Technology in Municipal Waste Water Treatment 2
151
Figure 2-87
Membrane bioreactor BioFilt with three lines at 4.5 m3 of permeate per day each [ROCHEM UF 2004]
Figure 2-88
Low-pressure reverse osmosis for grey water treatment for 600 m3 of permeate per day
[photo: ROCHEM UF 2004]
Membrane Technology in Municipal Waste Water Treatment2
2.4
Downstream Membrane Stage for Waste
Water Disinfection
2.4.1
Process Description and Fields of Application
The use of a membrane stage at the outlet of a waste water
treatment plant is applied to achieve disinfection of the
effluent to comply with higher standards (e.g. EU Bath-
ing Water Directive) or to reuse the treated waste water.
Disinfection by a membrane stage has advantages com-
pared to conventional processes such as UV treatment,
ozonation or chlorination. Namely, no undesired bypro-
ducts develop and the formation of chemical resistance
of bacteria and viruses is not supported [DORAU 1999].
For the most part, the waste water from the outlet of the
waste water treatment plant is pre-sieved with a molecu-
lar separation size of 500 µm before it is fed into the
membrane stage. Additional pretreatment is not neces-
sary. Removal of dissolved phosphate compounds after
disinfection can be achieved by arranging a dosing sta-
tion for precipitants upstream of the separation stage
[DITTRICH ET AL. 1998] to retain the precipitation sludge
in the downstream membrane stage.
2.4.2
Membrane Modules Used
Test studies (test installations of Berliner Wasserbetriebe
at the Berlin Ruhleben waste water treatment plant
[DITTRICH ET AL. 1998], plant at the Geiselbullach waste
water treatment plant [SCHILLING 2001] and tests at the
Hailfingen and Merklingen waste water treatment plants
[MAIER, VOGEL 2003]) have proven the suitability of dif-
ferent micro- and ultrafiltration modules for secondary
effluent disinfection. Table 2-23 presents the characteris-
tic values of the modules used for large-scale operation.
152
Table 2-23
Characteristic values of different membrane modules for the filtration of effluents from the test installa-
tions of Berliner Wasserbetriebe and the test installations at the Geiselbullach, Halfingen and Merklingen
waste water treatment plants
Manufacturer
Membrane process
Material
Module type
Nominal molecular
separation size
Mode of operation
Operating pressure
(transmembrane)
Specific flow
Backwashing
WWTP
Berlin-Ruhleben
[according to
DITTRICH ET AL. 1998]
MemBrain
ultrafiltration
ceramics
multichannel tube
module
0.05 µm
dead-end
0.5 – 2.0 bar
approx. 63 L/(m2· h)
with filtrate
(filtrate side)
WWTP
Berlin-Ruhleben
[according to
DITTRICH ET AL. 1998]
Memtec
microfiltration
PP1)
capillary module
0.1 µm
dead-end
0.5 – 1.5 bar
approx. 70 L/(m2· h)
with compressed air
(filtrate side)
WWTP Geiselbullach
[according to
SCHILLING 2001]
ROCHEM
ultrafiltration
PAN2)
cushion module
50 / 200 kD
dead-end
0.5 – 2.0 bar
approx. 45 L/(m2· h)
with filtrate (filtrate
side) and compressed
air (feed side)
WWTP
Bondorf-Hailfingen
ZENON
ultrafiltration
PVDF3)
capillary module
0.02 µm
dead-end
0.05 – 0.3 bar
approx. 40 L/(m2· h)
with filtrate (filtrate
side) and compressed
air (feed side)
WWTP
Merklingen
X-flow
ultrafiltration
PES4)
capillary module
150 kD
dead-end
0.5 – 2.0 bar
approx. 60 L/(m2· h)
with filtrate (filtrate
side)
1) Polypropylen 2) Polyacrylnitril 3) Polyvinyldiflourid 4) Polyethersulfon
UF2.4.4
Membrane Technology in Municipal Waste Water Treatment 2
2.4.3
Operating Experience
The effluent quality measured at the test installations at
the Berlin Ruhleben waste water treatment plant proves
that the limit values of the EU Bathing Water Directive
can be readily met with membrane treatment [DITTRICH
ET AL. 1998].
According to first experiences with the modules applied
up to now, specific flows of 35 – 70 L/(m2 � h) can be ap-
plied as a basis [DITTRICH ET AL. 1998; SCHILLING 2001].
To maintain the filtration capacity, High personnel and
financial expenditure for chemical cleaning must be con-
sidered.
First information on the treatment costs was acquired
with the help of semi-technical tests at Berliner Wasser-
betriebe. According to this information, in 1998 the spe-
cific total net costs for two different plant configurations
were between 0.25 euro/m2 and 0.42 euro/m2 of filtrate
[DITTRICH ET AL 1998]. In comparison, the costs of con-
ventional processes, e.g. consisting of sand filtration and
subsequent UV treatment, are between 0.15 euro/m2 and
0.31 euro/m2 [DOHMANN 1997].
Large-Scale Applications in Germany for Waste
Water Disinfection by Ultrafiltration
In Germany, three membrane installations are operated
currently which serve for further treatment of the effluent
from a conventional waste water treatment plant (Table
2-24). A technical installation has been operated since
July 2000 at the Geiselbullach waste water treatment plant
(Bavaria) of the Amperverband (water board). It treats the
effluent from the conventional waste water treatment
plant up to process water quality so that it can be used as
process water at the waste water treatment plant. Thus it
is no longer necessary to use groundwater for this purpose.
In 2004, two more membrane installations for down-
stream tertiary waste water treatment have been commis-
sioned after preliminary tests at the Hailfingen waste water
treatment plant of the waste water union Bondorf-Hail-
fingen and at the Merklingen waste water treatment plant
of the municipality of Merklingen. They are described in
the following sections.
153
Table 2-24
Membrane installations for waste water disinfection in Germany
Operator Amperverband Municipality of Merklingen Waste Water Union of
Bondorf-Hailfingen
Federal state Bavaria Baden-Württemberg Baden-Württemberg
Installation Geiselbullach WWTP Merklingen WWTP Bondorf-Hailfingen WWTP
Capacity 250,000 PE 2,300 PE 9,000 PE
Membrane manufactur Rochem X-Flow ZENON
Modul typs cushion module capillary module capillary module
Process ultrafiltration ultrafiltration ultrafiltration
Membrane surface area 480 m2 420 m2 7.560 m2
UF2.4.4.1
Membrane Technology in Municipal Waste Water Treatment2
Geiselbullach Waste Water Treatment Plant
Up to now, groundwater has been used as process water at
the Geiselbullach waste water treatment plant. The conser-
vation of this resource and closure of the process water
cycle, combined with a reduction of the waste water quan-
tity, were the reasons for further treatment of the effluent
of the waste water treatment plant and its reuse as process
water. Moreover, it was necessary to find an alternative to
the use of groundwater for cooling of the district-heating
power stations because of continuous problems with the
development of coatings on the heat exchangers due to the
iron and manganese concentrations in the water. The safe
and hygienic quality of process water treated by a mem-
brane process, compared to UV disinfection, was the reason
to decide on this technology.
After mechanical pretreatment, the waste water is treated
in the activated sludge stage which consists of a denitrifica-
tion zone, increased biological phosphorus removal and
a nitrification zone. A sand filtration unit is arranged
downstream of the final clarification (Figure 2-89).
The raw water for process water treatment is withdrawn
after sand filtration by means of a submerged pump install-
ed in the outlet shaft of the waste water treatment plant,
which pumps the raw water into the storage tank of the
membrane installation. For pre-treatment, a filter with a
molecular separation size of 500 µm and a flocculant
dosing unit for iron(III) chloride sulphate is arranged up-
stream. The pretreated water is fed into the ultrafiltra-
tion installation. It consists of cushion modules from the
company Rochem with 480 m2 of membrane surface area
in total, installed as cushion membranes in 60 pressure
tubes (Figure 2-90). The permeate volume flow is approx.
(V = 60 m3). The storage serves to ensure a sufficient pro-
cess water quantity in order to cover the peak loads with
up to 120 m3/h for some minutes. The specific energy
consumption of the installation is indicated with 0.5 kWh
per m3 of treated process water [SCHILLING 2001].
The investment for the process water treatment plant was
410,000 euro. The specific operating costs amount to
approx. 0.65 euro per m3 of treated process water. The
installation was commissioned in July 2000. Start-up and
optimization of the process technology engineering cover-
ed the period up to the year 2002.
154
primarytreatment
anoxic
sludge
clarifier
feed
screen gritchamber
anaerobic
recirculation
excesssludge
aerobicvariable
Ringlacecords
sand filtration
ultra-filtrationprocess water for
cooling the CHP
flocculant
storagetank
filter
receivingwater
Figure 2-89
Flow sheet of the Geiselbullach waste water treatment plant [according to AMPERVERBAND 2004]
UF2.4.4.2
Membrane Technology in Municipal Waste Water Treatment 2
Merklingen Waste Water Treatment Plant
The Merklingen waste water treatment plant, designed for
2,300 PE, is situated in the mountain region of Swabian
Jura. In the case of dry weather flow, about 300 m3 of waste
water per day are treated. During wet weather flow, this
quantity may increase to 2,000 m3/d.
Due to the special geological conditions of the Swabian
Jura, the treated waste water is discharged directly by an
infiltration shaft into the subsoil. The discharge location
is situated in the zone III of a water protection zone, so
that further treatment of the effluent became necessary.
155
sludge
feed
screengritchamber
concentrate
membrane system
nitrificationsimultaneous denitrification
clarifier storage
sand filter
sand filter
activatedcarbon
permeatstorage
Figure 2-91
Flow sheet of the Merklingen waste water treatment plant [according to RP TÜBINGEN 2004]
Figure 2-90
Treatment installation at the Geiselbullach waste water treatment plant [photos: AMPERVERBAND 2002],
left: pressure tubes of the membrane installation, right: process water storage tank
Membrane Technology in Municipal Waste Water Treatment2
Since July 2004, part of the treated waste water from the
effluent of the plant has been treated by two different
process technologies (ultrafiltration and slow sand filtra-
tion). An accompanying scientific program serves to com-
pare both technologies for advanced waste water treat-
ment with specific consideration of their capacity to re-
move filterable solids, bacteria etc.
As presented in Figure 2-91, the waste water is fed into
the activated sludge tank with a total volume of 366 m3
after having passed a rake screen with a spacing of 5 mm
and a grit channel. Denitrification takes place simultane-
ously with nitrification, the sludge is aerobically stabilized.
Following secondary clarification, one part of the waste
water is treated by a slow sand filter, the other one by
ultrafiltration (Figure 2-92). The membrane installation
contains pressure-driven capillary membranes from the
company X-flow with a molecular separation size of
150 kD. The total membrane surface area in 12 pressure
tubes is approx. 420 m2. The membranes are operated in
a dead-end process with inside-outside filtration. The maxi-
mum specific filtration capacity has been calculated as
60 L/m2· h.
The investment for the ultrafiltration system was about
530,000 euro. The state Baden-Württemberg has support-
ed the installation with a subsidy of 70 %.
156
Figure 2-92
Pressure tubes of the ultrafiltration plant at the Merklingen waste water treatment plant [RP TÜBINGEN 2004]
UF2.4.4.3
Membrane Technology in Municipal Waste Water Treatment 2
Bondorf-Hailfingen Waste Water Treatment Plant
The Bondorf-Hailfingen Waste Water Union was estab-
lished in 1971 for the treatment of the waste water from
the Associated Municipalities Bondorf and of the district
Hailfingen of the city of Rottenburg on Neckar. In 1974
the mechanical-biological Bondorf-Hailfingen waste water
treatment plant was built. From 1995 to 1999 it was up-
graded to achieve nitrogen elimination. Today the waste
water treatment plant with a design capacity of 9,000 PE
is operated according to the activated sludge process with
upstream denitrification, nitrification, biological phos-
phorus removal and aerobic sludge stabilization.
The dry weather flow to the waste water treatment plant
is 36 L/s on average, the storm weather flow is 67 L/s.
The plant is equipped with a mixing and compensating
tank (V = 1.690 m3), a screen (6 mm spacing), a grit and
grease trap, activated sludge tanks (V = 2.330 m3) and two
secondary settling tanks with a total volume of 1,190 m3
(Figure 2-93).
The positive results of the tests with three different mem-
brane installations in July and August 2003 were the rea-
son for the construction of a large-scale membrane instal-
lation with modules from the company ZENON which was
commissioned in December 2004. The installation is built
in two lines, each equipped with membrane cassettes of
the type ZW 1000. The pore size of the membranes is
0.02 µm on average. The total membrane surface area of
approx. 6,700 m2 generates a permeate volume flow of
approx. 3,100 m3/d.
The investment for the complete plant including build-
ing and civil engineering was about 1.25 million euro.
The state Baden-Württemberg supported the installation
with a subsidy of approx. 50 %.
The treated waste water is discharged into the Kochhart-
graben (Kochhart ditch). In summer, the flow of the Koch-
hartgraben is very low or it carries water only downstream
of the waste water treatment plant, respectively. In the
further course of the Kochhartgraben, the water infiltra-
tes into the subsoil. The plant is situated in a water pro-
tection area of the zone II a.
Due to this special situation, the geological conditions
and the need for groundwater protection, the water
management authorities made special demands on the
effluent quality concerning phosphate content, filterable
solids and disinfection (Table 2-25).
157
Table 2-25
Demands on the effluent quality and operating values of the Bondorf-Hailfingen waste water treatment
plant [BONDORF-HAILFINGEN WASTE WATER UNION 2004]
Parameter Unit Effluent final clarification Effluent membrane Requirements
Operating values installation
COD mg/L 30 < 25 60
BOD5 mg/L 4 < 4 15
NH4-N mg/L – – 5
Ntot mg/L – – 13
Ptot mg/L 1.1 0.3 0.3*
Filterable solids mg/L 15 - 30 n. n. < 5
Hygienics bathing water quality disinfection
* 24 h composite sampler
Membrane Technology in Municipal Waste Water Treatment2
158
recirculation
feed
screengritchamber
bio-P deni-/nitrifikation tank clarifier
mixing andcompensating tank
blowerinstallation
receivingwater
membrane system
excess sludgestorage
sludge
clarifier
Figure 2-93
Flow sheet of the Bondorf-Hailfingen waste water treatment plant [according to BONDORF-HAILFINGEN
WASTE WATER UNION 2004]
Figure 2-94
Membrane installation at the Bondorf-Hailfingen waste water treatment plant under construction
[photos: BONDORF-HAILFINGEN WASTE WATER UNION 2004], left: building with membrane installation,
right: tank for membrane modules
UF2.4.5.1
Membrane Technology in Municipal Waste Water Treatment 2
Large-Scale Applications Outside of Germany for
Waste Water Disinfection by Ultrafiltration
At present, few experiences exist in Germany with large-
scale membrane filtration of the effluent of secondary
treatment. However, some large-scale installations have
been built worldwide, e.g. in the U.S.A., Great Britain
and Australia [N.N. 2001; N.N. 1996; N.N. 1992]. Some
examples are described in the following sections.
Torreele, Belgium
To ensure that groundwater is used as basis for drinking
water at the Belgian North Sea shore, the groundwater
must remain uninfluenced by seawater. For this purpose,
a concept was developed in 2000 which comprises the
processing of treated waste water and subsequent infiltra-
tion into the dunes. This water serves for ground water
recharge under the dunes and thus prevents the infiltra-
tion of salt water. After approx. 40 days of underground
passage, it is reused as raw water for drinking water pre-
paration.
The treated waste water from the Wulpen plant is used as
feed water for this process. At the waste water treatment
plant Wulpen, the waste water is treated according to the
conventional activated sludge process with upstream de-
nitrification. The effluent values are compiled in Table 2-26.
The waste water treated by the Wulpen plant is fed via a
channel into the ultrafiltration processing plant which
consists of mechanical pre-filtration, a five-line ultrafil-
tration installation and a three-line reverse osmosis
system with downstream UV disinfection (Figure 2-95).
The plant from the company ZENON has an average treat-
ment capacity of 250 – 400 m3 permeate volume flow per
hour. The ultrafiltration plant has five lines. 25 cassettes
of the type ZW 500c are installed which treat up to
9,000 m3 of waste water per day. One part of the treated
waste water from ultrafiltration (about 10 %) is infiltrated,
the other part is further treated by reverse osmosis. The
reverse osmosis membranes have been provided by the
company Dow. The concentrate from the membrane
stage is discharged into the sea via a brackish water chan-
nel, approx. 90 % of the permeate is infiltrated.
The total investment of the processing plant was about
4.5 million euro. The energy demand for operation is
currently about 0.9 kWh per m3 of permeate [VAN
HOUTTE ET AL. 2004].
159
Table 2-26
Quality of the effluent of the Wulpen waste water treatment plant [ZENON GMBH 2004]
Parameter Unit Mean Maximum
COD mg/L 54 162
Cl mg/L 340 1,140
Suspended solids mg/L 5 19
Turbidity NTU 2 11
TS mg/L 1,130 1,950
UF2.4.5
Membrane Technology in Municipal Waste Water Treatment2
160
outlet
membrane stage
fine screen
fine screen
clarificationof WWTPWulpen
storage storage
NaOCl
blowerinstallation
infiltration
storage
reverse osmosis
storage
UV-disinfection
pond
90 %
10 %
Figure 2-95
Flow sheet of the Torreele treatment plant [according to ZENON GMBH 2004]
UF2.4.5.2
Membrane Technology in Municipal Waste Water Treatment 2
Katowice Treatment Plant, Poland
In Katowice, the effluent from the Katowice waste water
treatment plant is treated up to process water quality and
then used as cooling water for the Katowice power plant
situated at a distance of 12 km. The treatment takes place
with the help of a three-line ultrafiltration installation
from the company ZENON (Figure 2-96). Table 2-27 shows
the waste water quality at the inlet and outlet of the mem-
brane installation.
The ultrafiltration plant consists of 18 cassettes of the
type ZW500 and prepares approx. 5,600 m3 of process
water in total per day is processed, which is used as
additional cooling water for the cooling tower of the
Katowice power plant.
161
powerstation
additionalwater
clarifier
feed
blowerinstallation
blowerinstallation
blowerinstallation
membrane system
Figure 2-96
Flow sheet of the ultrafiltration installation for process water treatment in Katowice
[according to ZENON GMBH 2004]
Table 2-27
Waste water quality at the inlet and outlet of the ultrafiltration installation for treatment of the effluent
of the Katowice WWTP after secondary clarification up to process water quality [ZENON GMBH 2004]
Parameter Unit Inlet Outlet
COD mg/L 35 - 51 27 - 34
BOD5 mg/L 2 - 32 < 2.0
Suspended solids mg/L 6 - 32 < 1.0
Turbidity NTU 10 - 50 < 0.1
UF2.4.5.3
Membrane Technology in Municipal Waste Water Treatment2
Bedok Waste Water Treatment Plant, Singapore
The Bedok NEWater is the first of four planned plants
which treat waste water to meet the local industrial water
demand. The plant purifies the treated final effluent from
a municipal waste water treatment plant. To ensure the
water quality for reuse of the waste water in industrial pro-
duction, a decision was made In December 2001 on an
overall process concept consisting of ultrafiltration,
reverse osmosis and UV disinfection (Figure 2-97).
Figure 2-98 shows the waste water treatment plant with
the buildings for ultrafiltration and reverse osmosis.
The treated effluent from the waste water treatment plant
flows through a 0.5-mm sieve and is then fed into the
five-line ultrafiltration installation. To prevent the devel-
opment of germs in the membrane tanks, chlorine is added.
The installation is equipped with 70 capillary modules of
the type ZW 500c and has a capacity of 42,500 m3/d after
a first upgrade. Two expansions are already in the plan-
ning stage, so that the total capacity after completion
will be 117,000 m3/d.
The filtrate is discharged by a pump at a low pressure of
0.05 – 0.4 bar and fed into a reverse osmosis installation
for demineralization. Finally it is submitted to UV disin-
fection as a security measure. The concentrate is recycled
into the waste water treatment plant.
The water produced according to the multi-barrier system
is called “NEWater”. It is used as process water for the
electronic industry, for semiconductor manufacture and
also as cooling water for service buildings. A small per-
centage of the NEWater is also used for drinking water
preparation.
162
outlet
treatmentplant
UV-disinfection
fine sieve0,5 mm
ultrafiltration system
chlorinereverse osmosis
to industry
concentrate toWWTP
blowerinstallation
blowerinstallation
blowerinstallation
blowerinstallation
blowerinstallation
Figure 2-97
Flow sheet of the treatment plant [according to ZENON GMBH 2004]
Membrane Technology in Municipal Waste Water Treatment 2
163
2.5
Example for the Design of a Membrane Bioreactor
2.5.1
Design Basis
The basis for the following calculation is the approach of the University
Group (HSG).
Design basis: Type of plant: simultaneous aerobic sludge stabilization
without pretreatment
Population equivalent = 100,000 PE
specific waste water volume ws = 130 L/(E·d)
Daily inflow Q d = 19,500 m3/d
Sewer infiltration water flow Q f = 6,500 m3/d
Combined water flow Q m = 2.128 m3/h
Peak flow factor waste water xs = 14
Pretreatment = none
Fluctuation factor = 1.70
Dry matter content in the activated sludge tank TSBB = 12 g/L
alpha value � = 0.6
Resolubility factor (part of TKN in excess sludge) rX = 0
Sludge age tTS = 25 d
Temperature in the activated sludge tank T = 10 °C
Simultaneous phosphate precipitation with Fe(III)Cl
The design of secondary settling tanks is not necessary for membrane
bioreactors.
Figure 2-98
General view of the treatment plant [photo: ZENON GMBH 2004]
Figure 2-99
Ultrafiltration membrane installation
[photo: ZENON GMBH 2004]
Membrane Technology in Municipal Waste Water Treatment2
A waste water treatment plant of the size class 5
(> 100,000 PE) has to comply with the following
monitoring values:
Ninorg. = 13 mg/l
NH4-N = 10 mg/l
Ptot. = 1 mg/l
Norg. = 2 mg/l
A printout of the calculation results of the activated
sludge stage with the design program ARA-BER is enclosed
as chapter 2.5.4. Moreover, interim results are given in
order to explain the progression of design (see Table 2-29).
2.5.2
Interpretation of the ARA-BER Calculation
According to the Design Recommendations
for Membrane Bioreactors
The basis for the design of membrane bioreactors are the
tank volumes determined for a conventional waste water
treatment plant either according to ATV-DVWK-A 131 or
to the approach of the University Group (HSG), consider-
ing already a TS content which is typical for membrane
bioreactors. The data determined for the exemplary in-
stallation are listed in Table 2-28.
Due to the smaller reactor volume of membrane bioreac-
tors, undesired effects may occur, e.g. increased oxygen
carry-over from the nitrification or filtration zone into
the denitrification zone. To reduce these effects, the di-
mension of the denitrification zone (VDeni, MBR) should cor-
respond approximately with the dimension of the nitrifi-
cation zone (VDeni, MBR / VNitri, MBR = 1). The bigger of these
volumes of the conventional design (VDeni, conv,12 g TS/L or
VNitri,conv, 12 g TS/L) has to be equated with the corresponding
volume of the membrane bioreactor, since a smaller nitri-
fication or denitrification volume of the membrane instal-
lation (VDeni, MBR or VNitri, MBR) has to be included, compared
to a conventional design. To take special operating state
into account, a variable zone (Vvario) in the dimension of
30–50 % of the denitrification volume should be designed,
which can be arranged in the activated sludge tank ac-
cording to the needs of operation.
Moreover, a minimum retention time thydraulic ≥ 6 h (with
increased demands: thydraulic ≥ 8 h) has to be observed in
the case of certain boundary conditions. It is possible to
undercut the recommended retention time if the volume
required to maintain the recommended retention time is
bigger than the volume of the activated sludge tank of
the membrane installation, which in conventional design
has been determined with TSBB = 12 g/L and enlarged in
addition by 50 %.
164
VDeni, MBR : VNitri, MBR = 1
VMBR, tot. ≤ 1,5 � VBB, conv, 12 g TS/l
thydraulic ≥ 6 h
8,770 m3 > 5,520 m3
=> 2 � 8,770 m3 = 17,540 m3
Here assumption: xQmax = xS
=> xQmax = 14 h/d
=> Qcritical load case = Qd/xQmax
VBB, MBR = 17,540 m3
VNitri, MBR = 8,770 m3
VDeni, MBR = 8,770 m3
VBB, MBR = 21,435 m3
VBB, MBR = 8,357 m3
Table 2-29
Determination of the necessary volumes, taking into account different requirements for the design of
membrane installations
Requirements for MBR Interim result MBR
Table 2-28
Design results according to the approach of the
University Group (HSG) for a conventional waste
water treatment plant with TSBB = 12 g/l
VBB, conv, 12 g TS/L = 14.290 m3
VNitri, conv, 12 g TS/L = 8.770 m3
VDeni, conv, 12 g TS/L = 5.520 m3
VDeni, conv, 12 g TS/L / VBB, konv, 12 g TS/L = 0.386
Membrane Technology in Municipal Waste Water Treatment 2
After determination of the necessary volumes consider-
ing the different design criteria for membrane installa-
tions, the interim results are compared to determine the
decisive volume.
The Table shows that for this example the resulting vol-
ume is bigger than the volume necessary to maintain the
minimum retention time, considering the maximum
volume allowance of 50 % for the volume of the activa-
ted sludge tank in conventional design (VBB, conv, 12 g TS/L).
For this reason, the criterion VMBR, tot < 1,5* VBB,conv,12 g TS/L
is not decisive in this case. Now it has to be examined
whether the nitrification or denitrification volume is suf-
ficient. Due to the criterion of maximum retention time,
the required volume in this example is much smaller
than would be necessary for the compliance with the cri-
terion VDeni, MBR / VNitri, MBR. Therefore the criterion of mini-
mum retention time neither can be decisive for the design
of the membrane installation.The volumes decisive for
the example are listed in the following Table.
VBB,MBR = 17,540 m3
of which VNitri,MBR = 8,770 m3
VDeni,MBR = 8,770 m3
contained in it: Vvario,30% = 2,631 m3
or: Vvario,50% = 4,385 m3
In this case it is not possible to arrange compensating
volume because the total volume is required for the bio-
chemical processes. The resulting total retention time
with critical design inflow of Q critical load case = Q d/xQmax
= 1,393 m3/h is 12.6 h.
2.5.3
Design of the Membrane Filtration Stage
The surface areas of membrane filtration stages are de-
signed according to the permeate flow.
The membrane modules available on the market at pre-
sent have a design flow (net flow) of 25 L/(m3 · h) at 8 °C.
At a design temperature of 10 °C, the design flow may be
increased by 15 % (" design flow = 28.75 L/(m3 · h).
Necessary membrane surface area for the example in-
stallation:
Necessary information:
Design maximum flow Q m = 2,128 m3/h (in contrast to
the design of the reactor volume, the combined water
flow is always decisive in the determination of the neces-
sary membrane surface area of municipal membrane bio-
reactors!)
Design specific flow of 28.75 L/(m3 · h)
In addition, 1 % of the membrane surface area installed
must be maintained as reserve for cleaning measures (on
approx. 200 working days per year, 1 % of the surface area
is cleaned, i. e. the total membrane surface area is cleaned
twice a year).
From this results a necessary membrane surface area of
74,758 m3.
165
Membrane Technology in Municipal Waste Water Treatment2
2.5.4
Printout of the Design Results with ARA-BER:
Waste water treatment plant: membrane installation 100,000 PE
Type of installation: simultaneous aerobic sludge stabilization
Total volume: 17,530 [m3]
Nitrification volume: 8,765 [m3]
Denitrification volume: 8,765 [m3]
VDeni / Vtot : 0.500 [-]
Design temperature: 10.0 [°C]
Mean TS concentration: 12.00 [kg/m3]
Aerobic sludge age: 15.35 [d]
Total sludge age: 25.00 [d]
Effluent values:
NH4-N (peak) (design value) 10.0 [mg/L]
NH4-N (mean) (design value) 2.0 [mg/L]
NO3-N (average) (design value) 6.6 [mg/L]
Dry weather flow Q t 1,199 [m3/h]
Combined water flow Q m 2,128 [m3/h]
Daily flow Q d 19,500 [m3/d]
Backcharges:
BOD5 0.0 [kg/d]
TKN 0.0 [kg/d]
Ptot. 0.0 [kg/d]
Part of TKN in excess sludge = rX 0.00 [-]
TKN backcharge from rX 0.0 [kg/d]
Precipitation with: iron(III) salt
Precipitant dosage 17.42 [g/m3]
Attainable P effluent value 1.00 [mg/L]
No calculation of secondary settling tanks
166
Membrane Technology in
Industrial Waste Water Treatment
3
Membrane Technology in Industrial Waste Water Treatment3
3.1
Brief Overview
The application of membrane processes in industry has
its origin in the field of production, with most references
in the beverage industry and in the pharmaceutical in-
dustry and for the production of ultra-pure water [BROCK-
MANN 1998]. Due to rising costs for process water and
for waste water discharge as well as increasing environ-
mental awareness in industry, membrane processes are
now used more frequently for the treatment of industrial
waste water.
In industrial production, waste water is often produced
discontinuously and its composition may vary signifi-
cantly. Joint treatment of high-strength industrial waste
water in municipal waste water treatment plants gives
rise to problems, especially when the treatment efficiency
of the municipal plant is limited or its biological treat-
ment capacity is not sufficient. In these cases separate
treatment or pretreatment of industrial waste water is
required for which membrane processes, as process- and
production-integrated measures, can make an important
contribution.
The following chapter deals with the use of membrane
technology in industrial waste water treatment. Motives,
objectives and decision criteria for the use of membrane
technology are discussed, cost-benefit analyses are made,
and successful examples from practice are briefly described.
Figure 3-1 on the next page shows the contents of the
chapter. It presents the most important steps from the
motives and planning stage to the operation of a mem-
brane installation. With the help of references to page
numbers and short check lists the reader is able to focus
on individual sections of the chapter according to his
interest.
For successful operation of a membrane installation,
detailed planning and pilot-scale testing by specialists is
necessary, taking into account the existing boundary
conditions. Therefore the annex contains a list of con-
tacts for concrete planning intentions.
168
Membrane Technology in Industrial Waste Water Treatment 3
169
Figure 3-1
Motive – planning – operation of a membrane installation,
overview of the contents of the chapter “Membrane technology in industrial waste water treatment”
Procedure
Motive
Objective
p. 288
p. 170 ff.
Examples
Reduction of costs
Compliance with the standards
Information
Analysis of the actual situation
p. 288Incoming material flows
Outgoing material flows
Selection of processes
p. 288Separation processes
Membrane technology...
p. 174 ff.
p. 279 f.
Economic analysis
Comparison of processesCost-benefit relationPossibilities for promotion
Planning and pilot-scale testing
p. 174
Preliminary tests
Laboratory tests
Choice of membranes
...p. 174 p. 270 ff.
p. 289ConsultantsIndustrialsPlant manufacturersCleaning agent producer Membrane producer
Operation and control
p. 289Operator model
Owner-operated enterprise
p. 280 ff.
Concrete examples
Internet portalwww.pius-info.de
p. 177 ff.
p. 280 ff.
Effizienz-Agentur NRW
PIUS®-Check
Independent consultants
p. 172
p. 172
p. 177
Membrane Technology in Industrial Waste Water Treatment3
170
Avoidance of waste water
• Closure of circulation systems• Recycling of process water from
waste water
Optimization of treatmentprocesses
• Utilization of processes for com-pliance with effluent standards
• Improvement of effluent parameters
Reduction of space or volumerequirements for waste water
treatment
• Protections of sites
Recovery of reusable material
• For reutilization in the productionprocess
• As secondary raw material for processing
• For marketing
Minimization of discharge costs
• By production of pure material (e.g.non-polluted water or solvents)
• By concentration of pollutants
Reutilization of biomass
• By separation in the production inbiotechnical processes
• In biological waste water treatmentby recycling into the aeration reactor
Objectives
Economic interests
Figure 3-2
Objectives and economic interests for the use of a membrane installation in industrial waste water treatment
3.2
Objectives and Applications in Different Industrial
Branches
Membrane processes in industrial waste water treatment
can be arranged downstream of or integrated into the
production process. Besides compliance with legal
standards (for discharge into public sewer systems or
into water bodies), this technology is also used for econo-
mic reasons (Figure 3-2). Typical objectives for the appli-
cation of membrane technology in industry include:
• separation of reusable material, auxiliary agents, by-
products and solvents directly at the source of origin
• recirculation of partial flows
• avoidance of large high-strength waste water flows
• reuse of the concentrates as raw material or as secondary
raw material, or low-cost discharge
Membrane Technology in Industrial Waste Water Treatment 3
171
Food industry
Tanneries
Paper mills
Fibre industry (e. g. vulcanized fibre)
Textile industry
Plastics industry
Laundries
Metal industry, electroplating
Printers, paint shops
Car production
Petrochemical industry
Power stations
Mining industry
Navigation
Various branches, e. g. tanneries, breweries,
paper and textile industry
• Treatment of waste water for use as process water
• Higher protein output (potato starch production)
• Separation of precipitated heavy metals from waste water and reuse as recycling water
• Compliance with effluent standards
• Treatment of waste water for use as process water
• Recovery of reusable material (ZnCl2)
• Process water treatment
• Recovery of size baths and indigo dyes
• Separation of colour pigments
• Treatment of waste water for use as process water
• Separation of softeners and reuse of the treated waste water as process water
• Treatment of the waste water and reuse as process water
• Separation of oil and emulsions [DRIESEN ET AL. 1998] and recycling
• Recovery of scouring baths
• Treatment of rinsing water
• Recovery of coloured pigments
• Separation and concentration of mixed pigments to reduce the discharge costs
• Process water treatment
• Recovery of coloured pigments
• Treatment of reaction- and washing water [THEILEN 2000]
• Treatment of boiler feed water [THEILEN 2000]
• Treatment of mine water and radioactive surface water [THEILEN 2000]
• Separation of oil and emulsions
• Biological waste water treatment using ultrafiltration and microfiltration processes for biomass
separation (membrane bioreactor process)
Table 3-1
Objectives for the utilization of membrane technology in industrial waste water treatment
Industrial branch Examples of objectives
These process objectives may lead directly to cost-saving,
e. g. by
• reduction of the waste water load and possible reduction
of waste water levies for indirect dischargers or the waste
water charge for direct dischargers,
• savings of water and reusable material, if e. g. process
water is recycled or recovered.
The treatment of small specific volume flows may also
be profitable in cases where reusable material is saved or
recovered. Various objectives for the use of membrane
technology in industrial waste water treatment are sum-
marized in Table 3-1.
Membrane Technology in Industrial Waste Water Treatment3
3.3
Decision Criteria
Due to continuously rising costs for drinking- and pro-
cess water as well as for waste water discharge together
with increasing environmental awareness, industrial en-
terprises more and more frequently implement internal
measures to minimize the waste water load and quantity.
Such internal measures can be realized by using various
processes and process combinations. The choice of a
technically and economically suitable process requires
• structured analysis of the existing conditions and
• clear definition of the objective.
Figure 3-3 shows the methods and criteria of decision-
making for the selection of a suitable process. Since
membrane technology in industrial waste water treat-
ment is the focus of attention, the decision tree presents
two alternatives – membrane technique or alternative
processes – from which only membrane technology is
studied in more detail.
Prerequisite for the selection of a successfully and econo-
mical membrane process is a comprehensive analysis of
the production processes, the water used and the waste
water produced. If after first assessment of the boundary
conditions the use of membrane technology proves to be
technically feasible in an enterprise, an adequate installa-
tion can be planned. Planning has to be carried out
step by step, so that the final result will be adapted
most favourably to the separation problem. The planning
stages for the realization of a large-scale installation are
presented in the flow sheet (Figure 3-3).
172
Each planning phase comprises other detailed decision
criteria which should be examined individually and coor-
dinated by the entrepreneur together with the membrane-
and plant manufacturer. As a rule, existing knowledge
about the waste water to be treated should be used, and
tests on different scales are imperative.
Table 3-2 summarizes the working steps which can be
carried out on the different scales. Careful planning is
critical for successful operation of each membrane instal-
lation.
Membrane Technology in Industrial Waste Water Treatment 3
173
separation ofsubstance mixture
production ofprocess water
separation ofbiomass
identification of the flow(s) to be treated
avoidance or reductionpossible?
realization ofmeasures
terms of reference/objective
yes
no
quality requirements
possibilities for reuse
raw waterquality (physical and chemical)
reusable and hazardous materialquantity produced
boundary conditions
concept of treatment strategy
alternativeprocesses
yes
under certaincircumstances
draft of the flow sheet
identification ofmembrane material
assessment of membraneperformance
is the processexpected to be profitable? no
yes
energy costsmembrane replacement
cleaning agentsnumber of cleanings
staff/service
choice of membrane (membrane material, membrane geometry)
positive test results ?
yes
preliminary tests (laboratory)
choice of module
pilot teststechnical optimizationmodule formpretreatment
hydraulic conditions
economic optimizationoperating costs
overall economic efficiency
technicallyoptimized ?
economicallyoptimized ?
no no
yesyes
large-scale installation
control of operation
benefitrecovery of reusable material
saving of discharge costssaving of water and waste
water costs
costsinvestments
operating costs
filtrate performance
retention rates
economic efficiency
cleaning and backwashingintervals
pressure conditionsdevelopment of covering layer
membrane techniquepossible ? no
hydraulic efficiency
pretreatment/combination with other processes
no
separation ofreusable material
…
Figure 3-3
How to proceed in the planning of an installation for industrial waste water treatment
Membrane Technology in Industrial Waste Water Treatment3
3.4
Economic Efficiency of Membrane Installations
in Industrial Waste Water Treatment
An important decision criterion for the choice of a waste
water treatment process is its economic efficiency. It can
be assessed, for example, with the help of a cost-benefit
analysis and requires knowledge or estimation of the
costs and the resulting benefits.
From the examples in chapters 3.5 and 3.6 it is clear that
membrane technology (membrane processes and mem-
brane bioreactors) is used in most different industrial
branches for the treatment of waste water. These concrete
examples contain information about investments and
operating costs as well as the resulting amortization period,
as far as these data are accessible to the general public.
These indications only apply to the individual case. In
general, transfer to other installations of the same type is
not possible because the specific boundary conditions
(e. g. production process and techniques) influence the
costs in a significant way.
Due to some important factors of influence on costs and
economic efficiency (Figure 3-4) of a membrane installa-
tion, this chapter can give only qualitative information
on the costs. These factors are explained below.
174
Laboratory
Pilot scale
Planning of the installation
Large-scale installation
• Complete analysis of the waste water to be treated
• Choice of the membrane in a test cell installation
• Approximate determination of the most important process-engineering parameters such as trans-
membrane pressure and flow velocity
• First tests on membrane cleaning
Operation of a pilot installation:
• Choice and test of the modules, module connection
• Process optimization
On-site under operating conditions:
• Cleaning intervals and demand for chemicals
• Energy demand
• Product quality in continuous operation
• Analysis of the test results
• Design of the installation
• Analysis of economic efficiency
• Control and optimization
– of the operating parameters
– of the energy demand
• Determination of the overall efficiency (cost-benefit relation)
Table 3-2
Sequence of planning for a membrane installation [according to THEILEN 2000; PETERS 2001]
Scale Working steps
Membrane Technology in Industrial Waste Water Treatment 3
End use, or tasks and objectives
• Membrane installations are designed for a specific task
or treatment objective. In many cases, treatment beyond
this objective is possible, but often involves additional
costs.
Boundary conditions
• The waste water characteristic determines the required
investment and operating costs of a membrane installa-
tion. The waste water treatment costs may significantly
differ, even for enterprises of the same branch. It is not
useful to give numerical values because this might lead
to inaccurate assessment of the economic efficiency of
a membrane installation.
• The cost-benefit relation of a membrane installation
may be positive or negative, depending on a large num-
ber of boundary conditions. These are for example the
water and waste water charges, the design capacity, pos-
sibilities and costs for waste disposal, etc. More exam-
ples for boundary conditions influencing the costs are
presented in.
175
tasks/objectives
boundary conditions
...freshwaterprice
waste watercharges
energy costshydraulicefficiency
waste waterquantity
qualityrequirement
location
planning and pilot tests
membrane bioreactor membrane process
investments
• membrane material• membrane surface• module form• peripherical equipment
operating costs
• operating mode• annual operating period• energy demand• cleaning• cleaning agent• cleaning interval• membrane replace- ment• discharge costs• personal mainte- nance• insurance• costs for the building
benefit
• protection of the plant location• compliance with limit values• reduction of waste water charges• reduction of discharge costs• recirculation• recovery of reusable material
Figure 3-4
Factors influencing the economic efficiency of membrane installations
Membrane Technology in Industrial Waste Water Treatment3
Planning, pilot tests and choice of the membrane
process
• Since each industrial enterprise produces a specific
waste water, a detailed planning and pilot test phase is
necessary to examine the possible use of a membrane
process and to assess the costs. The expense for pilot
tests, which may vary considerably, also belongs to the
costs for a membrane installation. Detailed planning
and comprehensive pilot tests contribute to avoiding
uneconomical design of the installation, to recognize
possible operating problems and to counteract them in
advance by corresponding design and operative
management.
• The type of the membrane process has an effect on the
investments and the operating costs. The membrane
bioreactor has been assessed since 1997 as an economic
treatment process for concentrated waste water, e. g.
some industrial waste waters [ROSENWINKEL ET AL.
1997], while up to now this is true only to a limited
extent for municipal waste water applications.
For each plant, investments and operating costs have to
be distinguished. Both categories can be subdivided into
more individual factors.
The amount of investments depends among others
on the membrane material, i. e. the module costs, and
the membrane surface area installed. This is especially
true for large installations. Membrane material, surface
and form are chosen for the individual case considering a
number of criteria. STROH ET AL. [1997] compared for
two applications – clarification of fruit juice and oil/water-
emulsion filtration – the amount of investment and ope-
rating costs resulting from the use of polymer and cera-
mic membranes. It turned out that the investment and
the power demand for ceramic membranes are higher,
but that the costs for replacement of the membranes at
the same time are lower because of their longer service
life. Related to a cubic meter of filtrate, the use of cera-
mic membranes may be more favourable in one case,
while the use of polymer membranes is more favourable
in another one. The authors therefore emphasize that
without exact relation to a concrete case, only general
assessment is possible. With further developments in the
field of membrane technology (membranes, modules,
energy demand, etc.) the costs for the different materials
and modules will also change. With view to the product
and market development, it is expected that the prices
for membranes in general will decrease.
To ensure profitability of a membrane installation, full
use of the membrane surface by an optimal operating
mode is essential because the costs rise with increasing
membrane surface area. However, doubling of the mem-
brane surface area does not result in a doubling of the
costs, since the expense for peripheral equipment of the
installation, such as measurement and control technique,
has larger impact on smaller installations [e. G. VOSSEN-
KAUL, MELIN 2001].
The operating costs comprise several components. An
important component is the energy cost which depends
on the annual operating period and the operating mode
(cross-flow or dead-end). The energy demand of installa-
tions working in dead-end mode is lower than that of
installations operated in classical cross-flow mode.
Depending on each single case, the costs for membrane
cleaning must not be neglected. Optimized cleaning
methods (chemicals, cleaning intervals) contribute to
minimize these costs and possibly extend the service life
of the membranes. The longer the service life of the mem-
branes, the lower the costs for membrane replacement.
The service life of membranes may significantly vary de-
pending on the membrane material, waste water compo-
sition, pretreatment, operating period and operating mode
(chapters 3.5 and 3.6, Concrete examples). In some cases
(e. g. treatment of landfill leachate), service lives of five
years and more are standard.
Moreover, the operating costs also include the discharge
costs, insurance, personnel and maintenance costs. Per-
sonnel and maintenance costs are assessed in most cases
as flat rate in percent of the investment costs, but they
also depend on the size of the installation. For example,
a study of the economic efficiency of installations for
sludge water treatment has shown that this value as a rule
should be corrected: for small installations it is higher, for
large installations it is lower [VOSSENKAUL ET AL. 2000].
176
Membrane Technology in Industrial Waste Water Treatment 3
The breakdown of investments and operating costs is not
necessary for the user of an installation run according to
an operator model, e. g. “BOO” (Build-Own-Operate).
With this accounting method, the user of the installation
reimburses the quantity of treated waste water according
to a volume-specific price which already includes all costs
of waste water treatment.
The expenditure for a membrane installation is always
seen in relation to the benefit and the savings expected.
The benefit may consist of the protection of the enter-
prise location, compliance with limit values or the reduc-
tion of waste water charges and discharge costs. Savings
can be made by recirculation (recycling of process water
or recovery of reusable material). In some cases these
savings are very high, so that the membrane installation
is amortized after a rather short time. But the amount of
savings compared to the expenditure and the amortiza-
tion time to be expected have to be examined for each
single case.
3.5
Sample Applications of Plants in Germany
In the following subsections the employment of different
membrane processes in various industrial branches in
Germany is presented with the help of exemplary instal-
lations which have been built on industrial scale and are
operating successfully or a in planning stage. Some of
these installations have been realized with the financial
backing of the Ministry for Environment and Nature
Conservation, Agriculture and Consumer Protection of
the federal state North Rhine-Westphalia (MUNLV NRW).
Examples from international practice are described in the
subsections of chapter 3.6.
Diverging from the sorting of the installations for muni-
cipal applications (see chapter 2.2), the examples are
sorted according to their use in industrial branches,
because combinations of different membrane processes
are also used in industrial waste water treatment. A short
introduction into the respective industrial branch prece-
des the description of the example installations. As intro-
ductory overview for each concrete example, the mem-
brane process applied, the objectives attained or the
benefit of the installation are indicated.
All examples described in the following sections are com-
piled in Table 3-3. The addresses of the companies and
enterprises are listed in the annex.
Statements on the total economic efficiency of the pro-
cesses described are made for the following concrete ex-
amples as far as information was available. For the total
economic efficiency of a membrane installation, besides
the construction, the choice of the operating parameters
is decisive above all and which can be optimized in detail
only when the installation is finished. Since some of the
examples described are rather new or in planning stage,
only limited operating experience exists for some of the
installations, especially concerning the service life of the
membranes. Only after a longer practical operating peri-
od, experience will show how successful and economic
membrane processes are in each single case.
The installations described are examples for large-scale
realization of the membrane process. Normally they can-
not be transferred as a standard solution to another enter-
prise of the same industrial branch. The employment of
membrane technology has to be examined for each sin-
gle case concerning technical feasibility as well as econo-
mic efficiency.
177
Membrane Technology in Industrial Waste Water Treatment3
178
Potato starch
industry
Malthouses
Food industry
Printing industry
Paper mill
Textile industry
Textile industry
Textile industry
Fibre industry
Plastics industry
Laundry
Laundry
Metal proces-
sing industry
Metal proces-
sing industry
Metal proces-
sing industry
Metal proces-
sing industry
Table 3-3
Sample applications for the use of membrane technology in industrial waste water treatment in Germany
Branch of
industry
Emsland Stärke
Durst Malz -
H. Durst Malz-
fabriken
Beeck Feinkost
Peter Leis
Paper mill Palm
Drews Meerane
Silk weaving
mill Pongs
Gerhard van
Clewe
Vulcanized fibre
Troplast
Laundry Alsco
Textil Service
Mewa
Rasselstein
Hoesch GmbH
Faurecia, Bert-
rand Faure Sitz-
technik
Electroplating
Enterprise
Rudolf Jatzke
Wieland Werke
Company
Emlichheim
Gernsheim
Hamburg
Solms
Eltmann
Meerane
Mühltroff
Hamminkeln-
Dingden
Geldern
Troisdorf
Kaiserslautern
Groß Kienitz
Andernach
Stadthagen
Bielefeld-Senne-
stadt
Langenberg
Location
1997
1997
1994
1998
1999
2001
2004
UF/NF/RO: 1997
MF: 2001
1997
1998
2000
1998
1999
2000
1993
1998
Start-up
RO
RO
UF
UF
NF
UF
MF
MF/UF/
NF/RO
RO
UF
UF/NF
UF/NF
UF
UF
Membrane
electrolysis
UF
Membrane
process
Tube modules
Spiral-wound
modules
Tube modules
Ceramic tube
modules
Spiral-wound
module
Immersed capil-
lary modules
Plate modules
MF: tube modules
UF: ceramic
tube modules
NF/RO: spiral-
wound modules
Spiral-wound
modules
Ceramic tube
modules
UF: tube module
NF: spiral-wound
module
UF: ceramic
tube modules
NF: spiral-
wound modules
Ceramic tube
modules
Flat membranes
2 cells per dialy-
sator
Capillary modu-
les
Modules
5,000
1,333
100
2.4
15,000
2,200
320
MF: 225
UF/NF/RO: no
information
312
38
UF: 44
NF: 180
UF: 60
NF: 135
4.56
1.1
44
Membrane
surface area m2
3.5.1.1
3.5.1.2.1
3.5.1.3
3.5.2
3.5.3.1
3.5.4.1
3.5.4.2
3.5.4.3
3.5.5
3.5.6
3.5.7.1
3.5.7.2
3.5.8.1
3.5.8.2
3.5.8.3
3.5.8.1
Chapter
Membrane Technology in Industrial Waste Water Treatment 3
179
Treatment of
waste water
from car pain-
ting
Treatment of
waste water
from car pain-
ting
Pharmaceutical
industry
Landfill leachate
Fish hatchery
Power plants
De-oiling of bilge
water
Swimming pool
Swimming pool
Table 3-3
Sample applications for the use of membrane technology in industrial waste water treatment in Germany
DaimlerChrysler
Ford Werk
Schering
Alsdorf-Warden
landfill
Pilot installation
GuD Dresden
Aquana Freizeit-
bad
Freizeitbad
Copa Ca Backum
Düsseldorf
Köln
Bergkamen
Alsdorf
Dresden
Würselen
Herten
1998
2001
2003
1999
2004
1996
1989
1998
1998
UF
NF
UF
RO
MF
UF
UF
UF/RO
UF
Plate modules
no information
Capillary modu-
les
Disc-tube
modules
Plate modules
Ceramic multich-
annel elements
Tube modules
UF: capillary
modules
RO: spiral-
wound modules
Hollow-fibre
modules
30
no information
15,840
460
21
15.2
23.6
UF: 42
RO: 140
300
3.5.9.1
3.5.9.2
3.5.10
3.5.11.1.1
3.5.11.2
3.5.11.3
3.5.11.4
3.5.11.5.1
3.5.11.5.2
3.5.1
Food Industry
The generic term food industry is comprised of a large
number of branches, such as the milk or meat processing
industry, processing of vegetables, finished products, the
beverage industry etc. Correspondingly, the waste waters
of the individual branches vary in their composition.
They have in common only high organic loads.
In the following the use of membrane technology for the
treatment of waste water from the food industry is described
for three branches – potato starch production, delicatessen
production and malt production – and presented with
the help of concrete examples.
Besides waste water treatment, membrane technology is
also used in the food industry for other purposes, such as
concentration (e. g. of juice, milk, whey, egg whites), fil-
tration (e. g. of juice, wine, beer) and alcohol removal
from beer. The alcohol fraction resulting from alcohol
removal is a suitable substrate for denitrification in waste
water treatment (as a methanol substitute).
Branch of
industry
Company Location Start-up Membrane
process
Modules Membrane
surface area m2
Chapter
Membrane Technology in Industrial Waste Water Treatment3
3.5.1.1
Potato Starch Production
In the Federal Republic of Germany, starch is produced
from maize, potatoes, wheat and rice. Of these raw mate-
rials the potato has the highest water content. For starch
production, the potatoes are carefully prewashed and then
ground, separated from the pulp water (0,76 m3 of pulp
water per ton of potatoes) and washed out. The starch is
produced from the ground potatoes, and the pulp water
is generally used to produce potato protein (Figure 3-5).
The residual pulp water is used for irrigation of farmland
or evaporated. Potato pulp, which contains fine-ground
peelings, cell walls, starch residues and pulp water, is de-
watered. In Germany and the Benelux Countries, potato
pulp has been used for many years as fodder for dairy
cattle and young stock, and also partly for fat stock.
The entire production process results in sweeping and
washing water, pulp water and starch washing water. The
amount of washing water is about 1.8 to 2.8 m3 per ton
of starch. Characteristic constituents are potato pulp
water ingredients, fibres and mineral components (earth,
sand etc.).
Potato starch is only produced only during a certain sea-
son. The Fertilizer Ordinance (1996) dictates the storage
of potato pulp and irrigation water between 15th Novem-
ber and 15th January (even longer in the case of frost)
and limits the application in autumn to a maximum of
80 kg Ntot/ha.
The concentration of the pulp water and closing of the
internal water cycle are suitable measures to manage the
production limitations defined above. This can be obtained
with the help of different procedures (e. g. membrane
technology).
180
potatoes
fibres potato pulp water
protein precipitation
soluble matter
potato protein
potato pulp
grater fractionation (wet procedure)
starch
Figure 3-5
Flow chart of potato starch production
RO3.5.1.1.1
Membrane Technology in Industrial Waste Water Treatment 3
The company Emsland Stärke GmbH is the most impor-
tant producer of potato starch in Germany and is one of
the world’s leading manufacturers of finished starch pro-
ducts, potato protein, amino acids and sugar products
such as glucose syrup. The parent plant in Emlichheim,
established in 1928, has 405 employees. For the produc-
tion of potato starch, starch derivates and potato protein,
water with drinking water quality is used and ultimately
disposed of as waste water (sweeping and washing water,
derivate waste water).
In 1997, a reverse osmosis installation from the com-
pany Stork was commissioned in the Emlichheim plant
in order to reduce the quantity of waste water to be
disposed of, to conserve drinking water and to recover
more protein. The potato pulp water from starch produc-
tion is separated in the cross-flow mode at an operating
pressure of 40 bar. Tube modules with a total membrane
surface area of 5,000 m2 filter a feed volume flow of
140 m3/h. With daily backwashing and cleaning with
commercial enzymatic cleaning agents, the service life of
the membranes is about 6,000 hours. During the produc-
tion campaign (about 120 days per year), the installation
works 24 hours per day, so that the membranes have to
be replaced after approx. two campaigns.
181
potatoes
starch factory
evaporation
waste watertreatment plant
for fumes condensate
water supply
treatment
fibres
potato pulpwater reverse osmosis
protein production
potato pulp
permeate forpotato washing
potato protein
process water
fumes condensate
excess
brinefertilizer
feedmolasses
receiving water
process waste water
Figure 3-6
Flow chart of the treatment of process- and potato pulp water at Emsland Stärke GmbH
[according to LOTZ 2000]
Food Industry, Emsland Stärke GmbH
Start-up
Objectives
Membrane surface
Modules
Permeate volume flow
Pretreatment
Benefit
1997
Reduction of the waste water- and drinking water volume, higher protein yield
5,000 m2
Tube modules
62 m3/h
Separation of fibres and pulp water
Savings of energy, water, waste water, at the same time higher protein yield
Membrane process Reverse osmosis
Membrane Technology in Industrial Waste Water Treatment3
The permeate (about 62 m3/h) from the reverse osmosis
system is used to wash the potatoes, while potato protein
is produced from the brine. The remaining potato pulp
water is evaporated. The vapour condensates are fed to a
dedicated waste water treatment plant and recycled after
further treatment at drinking water quality into the pro-
duction process (see also Figure 3-6).
Thanks to the closed water cycle, more than 500,000 m3
of water are saved per year (250,000 m3 of washing water
by the permeate of the reverse osmosis installation and
more than 250,000m3 by closing the cycle with the vapour
condensates). Other advantages of the membrane instal-
lation are a drastic reduction in the waste water volume
and a higher protein yield.
3.5.1.2
Malt Houses
Malt is used as a raw material to produce alcohol from
starch-containing materials. Today a large number of brew-
eries get malt from commercial malthouses which pre-
dominantly use barley (about 2.5 million tons per year
[GUTSCH, HEIDENREICH 2001]) and partly wheat for
malt production. The malt production process can be
broadly subdivided into the steps cleaning, soaking, ger-
minating and kiln-drying [KRAFT, MENDE 1997]. Due to
high water consumption for washing and soaking, malt-
houses have to pay high costs for freshwater and waste
water disposal [GUTSCH, HEIDENREICH 2001].
For waste water whose pollution load comes mainly from
the production of malt from cereals and which is dis-
charged directly into a receiving water, the limit values
according to Appendix 21 of the Waste Water Ordinance
[ABWV 2002] are valid. Depending on the production
process applied, the waste water quantities and concen-
trations may vary significantly from one malthouse to
the other. Waste water constituents include suspended
substances (dust, earthy constituents, residues from cere-
als and husks), sugar, nitrogen-containing substances
(soluble proteins, vegetable fibrin), inorganic matter, and
possibly rubber and polyphenols.
For the treatment of malthouse waste water, membrane
technology can be used in various combinations which
have to be adapted to the specific case. Besides the exam-
ple described below, treatment by microfiltration in low-
pressure operation combined with a biological stage and
a closed process water cycle is also possible [KRAFT,
MENDE 1997].
182
RO3.5.1.2.1
Membrane Technology in Industrial Waste Water Treatment 3
Malthouse Durst Malz –
H. Durst Malzfabriken GmbH & Co. KG
The Heidelsheim company H. Durst Malzfabriken GmbH
& Co. KG is specialized in malt production for Pilsner
beer, but also furnishes special malt for other types of
brewing. 25 people are employed in the works in Gerns-
heim, one of the four plants which combined produce
about 230,000 tons of malt per year.
Large waste water quantities and disposal costs were the
motives for Durst Malz to cooperate with Schwander GmbH
at Bad Vilbel, which together with Frings Recycling-Anla-
gen GmbH (today: imb+frings watersystems gmbh) de-
veloped the patented FriSch-Verfahren® (FriSch process)
for the treatment of process water in the malt and bever-
age industry.
Promoted by Hessische Landes- und Treuhandgesellschaft
(HLT) Wiesbaden, today Investbank Hessen (IBH), an in-
stallation for the treatment of the malthouse waste water
was commissioned in 1997 at Gernsheim (Figure 3-7).
Since that time a daily amount of 700 m3 of water, con-
sisting of the barley soaking water and the washing water
of the production plants, is treated.
The malthouse waste water has a high COD content of
approx. 2,500 to 3,000 mg/l. By biological (SBR process1))
and physical-chemical (ferric chloride precipitation)
treatment, followed by fine filtration, this concentration is
reduced to 30 mg/l in the influent to the reverse osmosis
installation. Subsequently, spiral-wound modules in the
reverse osmosis installation (imb+frings watersystems
gmbh) with a total filter surface area of 1,333 m2 remove
all undesirable malting residues from the water at an
operating pressure of approx. 10 bar. The permeate com-
plies with the requirements of the Drinking Water Ordi-
nance and is recycled into the barley soaking process.
The remaining brine (about 25 – 30 % of the total inflow
to the membrane installation) is treated in the municipal
waste water treatment plant. In order to ensure the opera-
tion of the spiral-wound modules, an antiscaling agent is
used and the modules are backwashed daily with citric
acid.
The employment of the membrane installation led to a
reduction in the water demand and to considerable cost
savings concerning the waste water surcharge. Another
advantage is the modular construction of the installation,
as it can be adapted without causing problems to varying
production parameters.
183
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Benefit
1997
Reduction of waste water quantities and costs
1,333 m2
Spiral-wound modules
about 470 m3/d
Biological treatment (SBR), precipitation
Savings of freshwater and cost reduction in waste water treatment and disposal
Membrane process Reverse osmosis
1) SBR process: Sequencing-Batch-Reactor process. All phases of the treatment process run in succession in one reactor.
Figure 3-7
Reverse osmosis installation at Durst Malzfabriken
GmbH & Co. KG, Gernsheim [LINDEMANN 2001]
UF3.5.1.3
Membrane Technology in Industrial Waste Water Treatment3
The company BEECK Feinkost GmbH & Co. KG produces
delicatessen and salad dressings. More than 200 people
are employed at the site in Hamburg.
Tanks and equipment used in the preparation of delicates-
sen and salad dressings, tanks and equipment are regular-
ly cleaned using water and cleaning agents. During this
process solids as well as emulsified fats and oils get into
the waste water and give rise to high COD concentrations.
Treatment of the waste water by a grease trap was not suf-
Food Industry
BEECK Feinkost GmbH & Co. KG
ficient to comply with the COD discharge limit, and a sur-
charge for excess COD concentrations was paid by the
plant.
In order to reduce the waste water fees, an ultrafiltration
installation from the company KOCH-GLITSCH GmbH
was commissioned in 1994. First of all, the solids are se-
parated by prefiltration from the waste water (Figure 3-8).
The prefiltered water is fed to a tank from which the ultra-
filtration installation is charged. The installation is equipped
184
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Benefit
1994
Comply with the COD limit values and reduce the waste water fees (surcharge for heavy polluters)
100 m2
Tube modules
Depending on the production, 3.5 – 6 m3/h
Prefiltration
Saving of waste water fees
Membrane process Ultrafiltration
waste water
particles
100 %
pump shaft
prefiltration
tank 80 m3
disposal 1 %
collecting tank
ultrafiltration
sewer system 99 %
concentrate
measuring/monitoring
neutralisation
concentrate
filtrate
recirculationafter disconnectionof the inflow
Figure 3-8
Flow chart of the waste water treatment at BEECK Feinkost GmbH [according to KOCH-GLITSCH GMBH 2001]
UF3.5.2
Membrane Technology in Industrial Waste Water Treatment 3
with tube modules made of PVDF2) membranes with a
molecular separation size of 250,000 Dalton (KOCH-
GLITSCH GmbH), which are operated in cross-flow mode.
About 3.5 to 6 m3 of waste water per hour (depending on
the production) are filtered by 100 m2 of membrane sur-
face area at an operating pressure of max. 6.2 bar.
Depending on the production, the inflow to the tank is
closed so that the waste water is further concentrated by
recycling it to the ultrafiltration installation. The concen-
trate (1 % of the inflow) is disposed of, while the filtrate
(99 % of the inflow) is neutralized and discharged into
the sewer system.
The Grafische Handelsvertretung Peter Leis (graphical com-
mercial agency) at Solms, with five employees, supplies
printers with print drums and chemicals, e. g. cleaning
oils for printing machines.
One of the services of the company consists of voluntary
return of used adsorption oils from its clients. Therefore
a procedure has been developed which serves to convert
the polluted adsorption oils into a valuable reusable pro-
duct. This was done in cooperation with the companies
CARO Umwelttechnik GmbH (contact via NERAtec AG)
and Altenburger Elektronic GmbH.
Since autumn 1998, a membrane installation has been
operating to separate the components oil, water, dye par-
ticles and paper dust. The system consists of a micro-sett-
ling filtration step to remove coarse matter, an oil separator
and an ultrafiltration process to purify the oil phase.
Ceramic tube modules (from the company Tami) with a
total membrane surface area of 2.4 m2 produce about 30 L
permeate per hour at an operating pressure of approx. 3 bar.
On average, the ultrafiltration installation (Figure 3-9)
works 6 to 8 hours per day. Cleaning of the membranes
by removal and burning out becomes necessary after a
throughput of approx. 5,000 L. The service life of the
membranes ends on average after 20,000 L. The filtrate is
reused as recycled high-quality adsorption oil, the con-
centrate is recycled into the settling filtration stage.
The membranes are cleaned chemically once a week.
With this operating mode, the service life amounts to
4 – 5 years.
The installation has not only ecological advantages, but
is also profitable: By saving the surcharge for heavy pol-
luters, the investment for the installation is amortized
after three years.
185
Printing Industry, Peter Leis
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Benefit
Autumn 1998
To manufacture a reusable product from polluted adsorption oils
2.4 m2
Ceramic tube modules
30 L/h
Micro-settlement filtration to remove coarse matter, oil separator
Saving of waste water disposal costs and new adsorption oils
Membrane process Ultrafiltration
2) polyvinylidene fluoride
Membrane Technology in Industrial Waste Water Treatment3
Besides positive effects on the environment by closing
the product cycle, there are also economic advantages
from the use of this process combination. The yearly costs
for waste water disposal were halved, and the use of new
adsorption oils was reduced to only 25 % from which the
customers profit. Under the present operational condi-
tions, the amortization of the investment of 51,000 Euro
will be two years. These operational conditions were at-
tained about 1.5 years after start-up of the installation.
3.5.3
Paper Mills
Paper mills belong to the group of major industrial water
users. Water is needed for the production of printing pa-
per for the press to process the fibrous raw material as
well as for the production process in the paper machine
itself. The water is taken for the most part from rivers
and lakes and discharged after biological treatment. In
Germany the production of paper and cardboard is about
20 million tons per year, resulting in an average waste
water quantity of 10m3 per ton of final product [VDP 2004].
For the discharge of waste water from paper and cardboard
production into receiving waters, Appendix 28 of the
Waste Water Ordinance [ABWV 2002] is valid.
For the production of new printing paper form waste pa-
per, the applied printing ink has to be removed. Besides
water and air, auxiliary agents such as soap, sodium hydro-
xide, water glass, hydrogen peroxide and complexing agents
are needed. For the production of magazine paper it is
necessary to bleach the fibrous material.
In general, the waste waters from paper mills are highly
loaded organically. Their composition and other consti-
tuents, however, strongly depend on the raw material
used and the type of paper produced, therefore they may
differ considerably. Today membrane processes are still of
secondary importance in the treatment of waste water
from paper mills. In particular, the waste waters from
waste paper processing are nearly calcium-saturated which
leads to scaling. Moreover, they show high lignin contents
and a high percentage of fibrous material. Therefore the
use of membrane technology and of necessary pretreat-
ment measures have to be carefully examined and planned.
186
Figure 3-9
Ultrafiltration installation at the Grafische Handelsvertretung
Peter Leis [LEIS IN EFA 2000]
Membrane Technology in Industrial Waste Water Treatment 3
The paper mill Palm with its headquarters at Aalen-Neu-
kochen, Baden-Württemberg, belongs to the leading Euro-
pean manufacturers of newspaper printing paper and raw
paper for the production of corrugated cardboard. In the
works Eltmann in Bavaria, 250 employees produce news-
paper printing paper from 100 % waste paper.
From material processing and paper production results
waste water with COD and AOX loads, containing also
salts and dyes. In order to comply with the demands
for direct dischargers, the waste water is treated since
December 1999 by biological processes, followed by sand
filtration, and is then submitted to nanofiltration in
cross-flow mode by an installation from Wehrle Werk AG.
The installation has been promoted by the Deutsche Aus-
gleichsbank on behalf of the Federal Ministry for the Envi-
ronment, Nature Conservation and Nuclear Safety (BMU).
The polyamide-based spiral-wound modules (KOCH-
GLITSCH GmbH) used in nanofiltration are arranged in a
feed-and-bleed configuration (see chapter 1.5 and Figure
3-10). At an operating pressure of 3 to 7 bar, a total mem-
brane surface of 15,000 m2 treats a feed volume flow of
max. 195 m3 per hour. The output is 90 %, i. e. 175 m3 of
permeate per hour, which at present is still discharged
into the receiving water. Recycling of the permeate and
its use as process water are being planned. The concen-
trate is treated by lime milk and coagulants, an optimiza-
tion of this treatment is being planned, too.
At present, the modules are backwashed daily. Once a week
(depending on the operating pressure) they are chemical-
ly cleaned, so that the service life of the membranes is
estimated to be 2 – 3 years. These operating parameters of
membrane backwashing are still being optimized.
The membrane installation at the works Eltmann ensures
compliance with the discharge standards and thus serves
above all environmental protection. The planned closure
of the water cycle and utilization of the permeate as pro-
cess water will help to save freshwater, thus economic ad-
vantages are expected.
187
Paper Mill Palm, Works Eltmann
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Benefit
December 1999
Compliance with the standards for direct dischargers
15,000 m2
Spiral-wound modules
about 175 m3/h
Biological treatment, sand filtration
Compliance with the discharge standards; saving of process water after closure of the water cycle
Membrane process Nanofiltration
UF3.5.3.1
Membrane Technology in Industrial Waste Water Treatment3
3.5.4
Textile Industry
In Germany there are about 1,100 textile factories, approx.
150 of which are finishing works, which are, for the most
part, small to medium-sized businesses [GESAMTTEXTIL
2000]. From the different fields of production result pro-
cess waters whose composition reflects the diversity of
plant structures and production programs which vary
with the seasons of the year. The discharge of these pro-
cess waters gives rise to increasing costs.
The variety of processes in textile finishing hardly allows
general statements on the water consumption. However,
approx. 60 – 80 L of waste water, partly strongly coloured,
results from the finishing of 1 kg of textiles [MARZIN-
KOWSKI 1999]. Waste water from the cleaning of dye
preparation tanks is highly concentrated. On the other
hand, waste water from dyeing is loaded with dyes in
lower concentrations. With only a few exceptions, these
dyes are not biologically degradable or only partially de-
gradable under aerobic conditions [BRAUN ET AL. 1997].
Since many medium-sized textile finishing enterprises are
indirect dischargers, problems arise in municipal waste
water treatment due to the parameters COD and colour
[GUTSCH, HEIDENREICH 2001]. Direct dischargers have
to comply with the limit values according to Appendix 38
of the Waste Water Ordinance [ABWV 2002]. Besides pre-
cipitation, flocculation and chemical oxidation, membrane
technology can also be used to obtain further removal of
colour from textile waste water.
However, the great variety of waste waters from textile
finishing does not allow one to consider membrane pro-
cesses an economical and technically sound solution for
all applications in this field. Possible employment and
performance of membrane technology requires individ-
ual adaptation to each single case and location and should
be confirmed by detailed pilot tests. The treatment and
disposal of the brine are important considerations in the
overall economic efficiency of the process [MACHEN-
BACH 1998].
188
feed
concentrate
permeate
concentrate
permeate
concentrate
permeate
concentrate
permeate
concentrate permeate
1st circulation
2nd circulation
3rd circulation
4th circulation
Figure 3-10
Nanofiltration installation at the paper mill Palm, works Eltmann (left) [SCHIRM 2001] and detail of the
tube module arrangement as feed-and-bleed structure (right) [according to SCHIRM 2001]
Membrane Technology in Industrial Waste Water Treatment 3
Various process combinations for the treatment of textile
waste water are being tested or have been applied in
practice:
• To realize a closed water cycle in textile finishing, com-
bination of a biological stage (immersed biodisks),
cross-flow microfiltration and adsorption on activated
carbon (complete decolourization) have been tested
[WAIZENEGGER ET AL. 2000].
• Tests have proven the suitability of nanofiltration for
the treatment of waste waters from the textile industry.
Moreover, it was possible to close the water cycle by a
combination of ultra- and nanofiltration as well as to
The company Drews Meerane GmbH runs a textile finish-
ing plant from which high-strength waste water results.
The COD concentrations are between 1,000 and 1,500mg/L.
Moreover, the waste water is strongly coloured due to the
presence of by well water-soluble azo dyes.
The new concept for water and waste water management
intends separate treatment of partial flows with higher
and lower loads. A total of approx. 1,500 m3 of waste wa-
ter per day is treated by the waste water treatment and pro-
cessing plant. The share of the higher loaded waste water
is about 60 %. The COD concentrations in the higher
loaded flows are around 1,400 mg/L, in the lower loaded
flows approx. 1,100 mg/L.
The lower loaded waste water is treated by anaerobic and
aerobic processes, followed by sludge separation in a la-
mella separator (Figure 3-11). Finally the treated waste
water is discharged to the municipal waste water treat-
ment plant.
treat the concentrates in a biological fixed-bed reactor.
In Germany, this process combination has not yet been
realized on an industrial scale [SCHÄFER ET AL. 1997;
GUTSCH, HEIDENREICH 2001].
• In a large-scale plant, waste water from dyeing is treated
by a combination of a biological stage, adsorption, down-
stream reverse osmosis and activated-carbon filtration,
so that it can be directly discharged. The largest part of
the treated water is recycled into the production pro-
cess as all-purpose process water [BRAUN ET AL. 1997].
189
Textile Industry, Drews Meerane
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Benefit
2001
Reuse of the treated waste water
2,200 m2
Immersed capillary membranes
~ 34 m3/h
Bent-sieve screen
Reduction of fresh water consumption and of the waste water quantity, cost savings
Membrane process Ultrafiltration
UF3.5.4.1
Membrane Technology in Industrial Waste Water Treatment3
At first the higher loaded waste water is treated in an
anaerobic reactor to break down the azo dyes and other
dyes. The resultant products are much smaller and are
yellow up to colourless.
The waste water is then treated by an anaerobic process.
By means of the downstream lamellar clarifier, thickened
sludge is separated and recycled into the anaerobic reactor.
Complete separation of the solid and the liquid phase
takes place in the down-stream ultrafiltration system
with immersed capillary membranes from the company
ZENON. The membrane installation consists of six cas-
settes of the type 500c with a total membrane surface
area of 2,200 m2. Treatment of the higher loaded waste
water by this process combination achieves a reduction
of the COD concentration of 90 %. After final decoloura-
tion with ozone, part of the filtrate from the membrane
installation is used as recycled water with an average
COD concentration of 160 mg/L mainly in textile print-
ing processes for rinsing and cleaning purposes.
Thanks to this waste water treatment system, the COD
load to the nearby municipal waste water treatment plant
was reduced by approx. 500 kg/d. The economic efficien-
cy of the processing plant, compared to the conventional
waste water treatment plant operated in parallel, is achieved
at a recycling quote of approx. 26 %. The recycling quote
really achieved is much higher.
The project was promoted by Deutsche Bundesstiftung
Umwelt (German Federal Foundation for the Environ-
ment) and received in 2002 the Technology Promotion
Award of the Braunschweig Chamber of Industry and
Commerce.
190
flow to municipaltreatment plant
lamella separator
waste water treatment plant
lamella separator
waste water treatment plant
excess sludge
recirculationmembrane stage
ozonisation
well water
treated waste water
production
aerobicreactor
anaerobicreactor
aerobicreactor
anaerobicreactor
excess sludge blowerinstallation
Figure 3-11
Flow sheet of the waste water treatment and processing plant [according to ZENON GMBH 2004]
MF3.5.4.2
Membrane Technology in Industrial Waste Water Treatment 3
Since 1993, the PONGS Textil GmbH in Mühltroff pro-
duces and finishes large-dimensioned special clothes with
a width of up to 6,20 m, among other things. For this pur-
pose, sized warps and weft threads are used.
Before further processing, the raw material is washed to
remove sticking size baths as well as waxes and oils which,
in general, are hardly biodegradable. The washing tem-
perature is between 60 °C and 95 °C, depending on the
substances sticking to the raw material.
Due to increasing production and waste water quantities
and the resulting discharge costs, the textile company
was faced in 1999 with the decision either to relocate the
production to another site or to implement a process
concept that ensures waste water treatment in spite of
significant load variations and applies the reuse of a large
part of the treated waste water in the production process.
With the aim to lower the costs for the upgrading of the
existing waste water treatment plant, a concept was devel-
191
Silk Weaving Mill PONGS
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Benefit
2004
Reuse of the waste water/closure of water, circuits
320 m2
Double-decker modules/plate membranes
~ 2.5 m3/h
Vibrating screen
Expansion of the waste water treatment capacity Savings of costs for fresh water and waste water
discharge
Membrane process Microfiltration
Figure 3-12
Conversion of the waste water treatment plant at PONGS Textil GmbH, left: conversion of the existing
trickling filter to a membrane bioreactor [photo: A3 GMBH 2004], right: new membrane bioreactor
[photo: A3 GMBH 2004]
membran bioreactor
Membrane Technology in Industrial Waste Water Treatment3
oped in 1999 – 2000 that included converting the existing
trickling filter to a membrane bioreactor. Figure 3-12 shows
the conversion of the old trickling filter to a membrane
bioreactor (left) and the new membrane bioreactor (right).
This membrane bioreactor, realized as cascade, was run
until another capacity enlargement in 2004. It consisted
of two tanks arranged in series which were intensively
aerated. The second tank was equipped with immersed
membrane modules from the company A3. The filtration
capacity of the installation could be maintained for six
months without chemical cleaning of the membrane
modules. Depending on process needs, the treated waste
water was used as process water in the textile company
or discharged into the sewer system of the municipality.
The successful operation of the plant showed that the
treatment of waste water from desizing by membrane
bioreactor processes is technically feasible and also cost-
effective. Enlargement of the capacity, necessary due to
increasing production capacity, was realized in 2004 with
the membrane bioreactor process, too.
The daily waste water flow to this installation is approx.
60 m3 with COD concentrations from 8,000 mg/L to
15,000 mg/L. The waste water from the company PONGS
is buffered in a mixing and compensating tank and flows
via a vibrating screen with a molecular separation size of
100 µm to the membrane bioreactor stage. The activation
volume is 240 m3. The membrane installation consists of
four double-decker modules (plate membranes) from the
company A3. The pore size of the membranes is approx.
0.4 µm, the total membrane surface area is 320 m2.
A large part of the treated waste water is reused in the
production process. The company PONGS has set a treat-
ment target of COD concentrations < 200 mg/L for the
reuse of the treated waste water. This target is attained
with COD effluent concentrations of less than 100 mg/L.
192
processwaste water
blowerinstallation
membrane stage
vibrating screen100 µm
production
mixing andcompensatingtank
sewersystem
Figure 3-13
Flow sheet of the membrane bioreactor of the company PONGS [according to A3 GMBH 2004]
MF UF UF RO3.5.4.3
Membrane Technology in Industrial Waste Water Treatment 3
In 1954 the company Gerhard van Clewe has been estab-
lished at Hamminkeln-Dingden. In 1973 the enterprise
was expanded by a dye-works. Today, 190 employees in
total are occupied with the finishing of textiles of all types.
In textile finishing plants, different process waste waters
result from the production areas of pretreatment, dyeing,
dye preparation, washing machines, and finishing. Their
discharge gives rise to increasing costs. In order to reduce
these costs, the company van Clewe tried at first to reduce
as far as possible the water consumption in the finishing
process. As a result, the concentrations in the waste water
increased, and it was no longer possible to comply with
the limit values for AOX and heavy metals for the dis-
charge into the municipal waste water treatment plant.
Based on the results of a large number of tests with a pilot
plant, a large-scale membrane installation from the com-
pany CSM Filtrationssysteme GmbH & Co. KG, Bretten,
was commissioned in 1996. Following expansion of the
installation in 1997, which was promoted by Deutsche
Bundesstiftung Umwelt, Osnabrück, and scientifically as-
sisted by the University of Wuppertal, both partial flows
from the dye-house are fed separately to the membrane
installation. At operational pressures between 5.5 and 27
bar, the permeate output is max. 12 m3 per hour. The per-
meate is recycled to the pretreatment stage and the dye-
house.
The three-stage membrane installation which works in
the cross-flow mode serves to treat the partial flow con-
taining the waste water from cotton dyeing and mesh
finishing. It comprises the stages ultrafiltration (con-
struction and calculation by RIK, Dülmen), nanofiltra-
tion and reverse osmosis. To separate fluff and other
coarse matter, a screen (discotrainer) has been arranged
up-stream. In the ultrafiltration stage (Figure 3-14), cera-
mic tube modules from the company atech innovations
gmbh separate fine-particulate and dissolved polymeric
substances from the waste water. The filtrate passes a
downstream bag filter (protecting function) before it is fed
to the nanofiltration stage. In this stage, decolourization
and partial demineralization are obtained using spiral-
wound modules made from synthetic polymer from the
company Osmonics. The largest part of the salt and most
of the COD load are removed by reverse osmosis using
spiral-wound modules made from polymer membranes
(company Osmonics).
193
Textile Finishing Works Gerhard van Clewe GmbH & Co. KG
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Membrane process Microfiltration
Start-up
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Benefit
1997
no information
Ceramic tube modules (UF), spiral-wound modules (NF and RO)
12 m3/h in total
Screen filtration (discotrainer) upstream of the ultrafiltration to separate fluff and other coarse particles,
bag filter upstream of nanofiltration
Saving of process water and reduction of waste water costs
Membrane process Ultrafiltration, nanofiltration, reverse osmosis
2001
Reduction of the costs for waste water discharge and compliance with the requirements for indirect dischargers
225 m2
Tube modules
2.5 m3/h
Dosing of liquid polymer and clay minerals to increase the particle size (improvement of the separation capacity)
Membrane Technology in Industrial Waste Water Treatment3
The second partial flow has a smaller volume and is less
polluted. It consists of waste water containing pigment
dyes from dye preparation and dye coating, waste water
from the tenter driers as well as from the purification of
waste air from the tenter driers. Since the beginning of
2001, this partial flow is fed to a microfiltration stage
after dosing of clay minerals and coagulants to increase
the particle size and to improve the separation capacity.
The microfiltration has been designed by MDS Prozess-
technik GmbH and calculated by the company BKT Burg-
gräf GmbH. The installation is equipped with tube mod-
ules (Microdyn Modulbau GmbH) made from polymer
mebranes and works in the cross-flow mode. The mem-
brane surface with an area of 50 m2 in total processes a
permeate volume flow of 2.5 m3 per hour. The tube mod-
ules are backwashed periodically, and fully-automated
chemical cleaning takes place once a week.
After reverse osmosis, the permeate is colour-free and
contains only 3 % of the original COD load. This quality
is sufficient to reuse the permeate from the membrane
stage (single-stage and three-stage) as process water. Thus
a recycling rate of up to 50 % of the total waste water
amount is obtained. The concentrate from all stages is
evaporated, dried by film driers and discharged into an
incineration plant for household waste.
Only the membranes of the ultrafiltration stage have to
be backwashed every three minutes. With this operating
mode, the ultrafiltration membranes have been in service
for seven years without showing loss of capacity (as of
August 2005). The service lives of the nanofiltration and
reverse osmosis membranes are 1.5 years. They have to
be cleaned only on the weekend with special membrane
cleaning agents.
Besides compliance with the standards for indirect dis-
chargers, the membrane installation helps to save about
50 % of the waste water costs by a closed process water
cycle.
194
Figure 3-14
Ultrafiltration installation at the textile finishing
plant van Clewe [BÖTTGER 2001]
RO3.5.5
Membrane Technology in Industrial Waste Water Treatment 3
Vulcanized fibre is a versatile material produced from re-
newable raw material. It is manufactured from non-glued
cotton linters and pulp under the action of a zinc dichlo-
ride solution. The material is antistatic, elastic and of low
weight.
The 50 employees of the Ernst Krüger GmbH & Co. KG
at Geldern produce, among other products, seals, guides
for weaving machines and stamped parts from vulcanized
fibre for the car industry, electrical industry and textile
industry. An important production step is the washing
off of zinc dichloride by several baths connected in series,
from which results waste water containing a residual zinc
dichloride concentration.
Approx. 30,000 m3 of rinse waste water are generated per
year in the production process. The waste water was typi-
cally treated by conventional precipitation and floccula-
tion processes. The plant was interested in finding alter-
native treatment processes to reduce cost. In a prelimina-
ry study the Research Institute for Water and Waste Ma-
nagement (FiW) compared different processes and estab-
lished the contact with Amafilter Deutschland GmbH.
Since 1997 not only ultrapure water for rinsing purposes
but also a high-quality zinc dichloride solution for the
process bath have been recovered. This is made possible
by prefiltration and downstream reverse osmosis
(Amafilter Deutschland GmbH), which works continuously
195
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Benefit
1997
Cheap alternative for reduction of the rinsing water quantity and treatment of the zinc-dichloride waste water
312 m2
Spiral-wound modules
4 m3/h
Prefiltration
Saving of precipitation agents and flocculants, freshwater, waste water and zinc dichloride
Membrane process Reverse osmosis
equalization oflosses
5m3/h
concentrate1m3/h
permeate4m3/h
zinc dichlorideevaporator
water bath lye bath parchmentizing bath 70% ZnCl2
reverse osmosis
Figure 3-15
Flow sheet of the process water treatment at the vulcanized fibre works GmbH & Co. KG
[AMAFILTER 2001]
Fibre Industry, Vulcanized Fibre
Membrane Technology in Industrial Waste Water Treatment3
in the effluent of the water bath (Figure 3-15 and Figure
3-16). The spiral-wound modules with a total filter sur-
face area of 312 m2 treat a permeate volume flow of 4 m3
per hour, at an operating pressure of 25 bar. Practical
operation has shown that the service life of the mem-
branes is greater than three years (up to six years). When
the membranes had to replaced for the first time, another
type of membrane was chosen which resulted in an
increase of the capacity.
The permeate of the reverse osmosis installation has the
quality of fully demineralized water so that it can be re-
cycled to the water bath. The brine contains the zinc di-
chloride which is reused in the lye bath of the production
process.
Thanks to the financial backing of 50 % by a promotion
program3) of the federal state North-Rhine Westphalia, the
installation has been amortized after approx. four years.
The employment of the reverse osmosis installation in
continuous vulcanized fibre production as well as the
integration of other waste water flows and the cooling
water to reverse osmosis have economic and ecological
advantages. By closure of the water cycle the waste water
quantity was reduced by 80 % in total, and the freshwa-
ter demand by 90 % (about 18,000 m3 per year). Due to
this reduced demand, the costs for freshwater conditio-
ning (softening of well water) decreased.
Moreover, precipitation and flocculation agents are saved,
and through targeted recovery the zinc dichloride remains
in the production cycle, which minimizes the additional
demand for this chemical.
196
Figure 3-16
Reverse osomosis installation at the vulcanized fibre works Ernst Krüger GmbH & Co. KG [photo: AMAFILTER]
3) Promotion program (1997 – 1999) „Initiative ökologische und nachhaltige Wasserwirtschaft NRW“ (Action group Ecological and Sustainable Water
Management) [MURL 1996]
UF3.5.6
Membrane Technology in Industrial Waste Water Treatment 3
Since the beginning of the 20th century, special plastic
material has been produced by the company HT Troplast
AG in Troisdorf. Today the company has 1,500 employees
at this location, about 180 of them working in the Trosi-
fol branch, which produces safety-glass films for the car
industry and the building industry. In the course of the
production process, Trosifol, a flexible film on the basis
of polyvinyl butyral resin, is cooled. During this process,
undissolved plasticizers (oily) get into the cooling water.
To separate the plasticizers from the process water, the
company decided in 1998, after study of various proces-
ses and discussions with the company Amafilter Deutsch-
land GmbH, to commission an ultrafiltration installa-
tion with an upstream filter for the separation of coarse
matter (coarse filter, screen filter, cartridge filter). The
ultrafiltration installation is equipped with ceramic tube
modules fro the company atech innovations gmbh and
is completed with a heat exchanger for water cooling
(Figure 3-17).
The membrane surface area with a size of 38 m2 works in
cross-flow mode at an operating pressure of 4 bar and pro-
cesses a feed flow of 10 m3 per hour. 95 % of the inflow
are yielded as filtrate and fed back into the water cycle.
The concentrate is discharged by the waste water system.
The service life of the membranes is expected to be more
than 10 years.
Besides ecological advantages, the installation is also pro-
fitable. By reduction of the volume and the closed water
cycle, waste water costs and groundwater resources are con-
served, as the water consumption is reduced by 75 – 80 %.
Moreover, safe and low-maintenance process design has
contributed to the fact that the installation has been
amortized after 2.5 – 3 years, in spite of the rather high
investment of 348,000 Euro, which is due to full automa-
tion and corresponding control technology.
197
Figure 3-17
Ultrafiltration installation at the company
HT Troplast AG [photo: HT TROPLAST]
Plastics Industry, Troplast
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Benefit
1998
Recirculation of the cooling water which has come into contact with the product
38 m2
Ceramic tube modules
approx. 9.5 m3/h
Coarse filter, screen filter, cartridge filter
Saving of freshwater and reduction of waste water costs
Membrane process Ultrafiltration
Membrane Technology in Industrial Waste Water Treatment3
3.5.7
Laundries
Waste water from laundries can be loaded with danger-
ous pollutants. At present, laundry waste water is typical-
ly discharged with or without previous treatment into
municipal waste water treatment plants. There are still a
few laundries which discharge the waste water without
treatment into receiving waters [GUTSCH, HEIDENREICH
2001]. For the treatment of low-loaded waste water from
laundries (e. g. washing of hospital and hotel textiles),
which is then recycled, membrane filtration processes are
often used in addition to biological treatment systems
and their combinations with chemical precipitation
[MENGE 2001]. Installations for closing the water cycle
in laundries comprise either a combination of microfil-
tration and nanofiltration or a reverse osmosis system
[MENGE 2001].
Appendix 55 of the Waste Water Ordinance [ABWV 2002]
is valid for waste water which is discharged directly into
a water body and whose pollution load mainly results
from washing of dirty textiles, carpets, mats and fleeces
in commercial enterprises and public institutions. For
waste water from dry cleaning of textiles, carpets and
products made from fur and leather, Appendix 52 of the
Waste Water Ordinance [ABWV 2002] is valid.
198
Laundry Alsco
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Benefit
2000
Waste water treatment
44 m2
Tube modules
6.5 m3/h
Vibrating screen
Pretreatment prior to nanofiltration
Membrane process Ultrafiltration
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Benefit
2000
Waste water treatment
180 m2
Spiral-wound module
~ 6 m3/h
Ultrafiltration
Savings of costs for freshwater and waste water discharge
Membrane process Nanofiltration
UF NF3.5.7.1
Membrane Technology in Industrial Waste Water Treatment 3
Since May 2000, the company ALSCO has operated a
commercial laundry in Kaiserslautern. To separate the
partial flow, the laundry volume is allocated to special
engine groups which are connected by a pipeline system,
so that the waste water of the partial flows can be col-
lected and treated separately (Figure 3-18).
The waste water from the partial flow “mat cleaning/blue
laundry” consists of 30 m3/d of waste water from blue
laundry and 45 m3/d from mat cleaning. With a working
period of five days per week, the annual waste water quan-
tity from “mat cleaning/blue laundry” is 18,750 m3/a.
The partial flow “white laundry”, which comes from the
washing of work clothes, towels and flatwork, is about
95 m3/d. This waste water is collected and fed to a cooling
tower for temperature reduction, followed by neutralisa-
tion by means of CO2. The treated waste water of the
white laundry is discharged by the sewer system into a
municipal waste water treatment plant.
The waste water of the partial flow “mat cleaning/blue
laundry” is collected in an underground tank with a vol-
ume of approx. 5 m3. From there it is fed to a vibrating
sieve to separate fluff and other coarse particles. After
having passed the vibrating screen, the waste water is
cooled down to a temperature of 38 °C by a condensation
cooling tower and pumped into an aerated volume com-
pensating tank which holds approx. 65 m3. From there it
is fed into the activation reactor which also holds 65 m3.
After treatment in the activated sludge stage, the
waste water and the activated sludge are thickened in the
cross-flow ultrafiltration system to a solid matter content
of approx. 4 %. About 10 m3 of wet sludge per month are
discharged to a waste water treatment plant at a local
chemical industry.
The ultrafiltration plant (Figure 3-19) contains four
pressure pipes with 11 m2 of membrane surface area each
and two empty pipes for future expansion. The mem-
brane modules are equipped with organic tube modules
from the company Berghof with a free duct of 10.2 mm.
The permeate volume flow is approx. 6.5 m3/h.
199
blowerinstallation
washingwater neutrali-
sationwhitelaundry
recirculation
biologicalreactor
coolingtower sewer system
nano-filtration
ultra-filtration
wet sludgeconcentrate
concentrate tothe sewer system
process water recycling
tank
tankvolumecompensatingtank
coolingtower
blue laundryand mats
vibratingsieve
Figure 3-18
Flow sheet of the waste water treatment process in the laundry ALSCO
[according to WEHRLE UMWELT GMBH 2004]
Membrane Technology in Industrial Waste Water Treatment3
The COD concentration in the waste water from mat
cleaning/blue laundry is 2,800 mg/L on an average and
maximally 5,000 mg/L. The COD concentration in the
permeate from the ultrafiltration system is between 80
and 150 mg/L. AOX compounds do not occur because
chlorine bleach liquor is not used in the washing process.
The permeate from the ultrafiltration meets the require-
ments according to Annex 55 of the Waste Water Decree
and can be discharged into the local sewer system. The
specific energy consumption of the ultrafiltration is
approx. 4.0 kWh per m3 of permeate.
To reduce the fresh water and waste water costs at the
laundry, the waste water treated by ultrafiltration is further
treated by nanofiltration and reused as washing water.
The single-stage nanofiltration plant is equipped with
spiral-wound modules from the company Desal. The per-
meate is used again as washing water. The concentrate
flow (10 – 15 m3/d), which meets the requirements for in-
direct dischargers and those made by the local waste water
statutes, is discharged together with the waste water from
the white laundry into the municipal waste water treat-
ment plant.
The costs of membrane cleaning have been determined
as approx. 1 – 2 Cent/m3 of waste water.
The service life of the membranes has been calculated as
4 – 6 years. With a service life of four years, membrane re-
placement costs of about 0.15 Euro per m3 of waste water
will become necessary.
According to the supplier of the plant (Wehrle Umwelt
GmbH), the specific operating costs of the ultrafiltration
system as sum of energy-, membrane replacement- and
cleaning costs are approx. 0.40 Euro per m3 of waste
water.
200
Figure 3-19
Membrane installation in the laundry ALSCO [photos: WEHRLE UMWELT GMBH 2004],
left: ultrafiltration installation, right: complete installation
UF NF3.5.7.2
Membrane Technology in Industrial Waste Water Treatment 3
At the site Groß-Kienitz, the textile service Mewa cleans
very dirty work clothes from the industrial branches
metal industry, mechanical engineering firms, motorcar
repair shops, etc. On account of legal constraints, the
waste water treatment process had to be upgraded in
1997. According to Annex 55 of the Waste Water Ordi-
201
Textile Service Mewa GmbH
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Benefit
1998
Closed washing water circuits
60 m2
Ceramic tube modules
~ 4 m3/h
Prefiltration / fluff sieve
Reduction of the fresh-water demand and savings of detergents
Membrane process Ultrafiltration
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Benefit
1998
Closed washing water circuits
135 m2
Spiral-wound modules
~1,5 m3/h
Ultrafiltration
Reduction of the fresh-water demand
Membrane process Ultrafiltration
prefiltrationbuffer andprecipitation
ultra-filtration 1
1,5 m3/hrecycling water 1for preliminary andgeneral washing
concentrate toexternal discharge
concentratestorage
ultra-filtration 2
sewer system
nano-filtration
1,5 m3/hrecycling water 2for process water
feed
Figure 3-20
Flow sheet of the treatment plant of Textile Service Mewa GmbH [according to ENVIRO CHEMIE 2004]
Membrane Technology in Industrial Waste Water Treatment3
nance, heavy metals and hydrocarbons have to be re-
moved before the waste water can be discharged into the
public sewer system.
A treatment plant has been run since 1998 at the site of
the laundry. The treatment plant treats 100 m3 of laundry
waste water per day to such an extent that it can be re-
used in the washing process. Figure 3-20 shows the flow
sheet of the treatment plant.
After having passed a prefiltration and precipitation stage,
the waste water flows into the first ultrafiltration stage
which consists of six modules with 47 ceramic bars each
(Figure 3-21)
By filtration over the total membrane surface area of
approx. 60 m2, a permeate volume flow of approx. 4 m3/h
is attained. About 30 % of the permeate volume flow of
the ultrafiltration plant is reused as recycling water 1.
The quality required for the recycling water 1 is COD <
1,000 mg/l and a residual mineral oil content of < 20 mg/L.
Due to the residual organic load it can be used only to a
limited extent in the preliminary and main washing pro-
cesses. However, about 20 % of washing agents can be
saved thanks to the high detergent content in the recyc-
ling water.
The remaining permeate of the first ultrafiltration stage
further treated by a downstream nanofiltration stage con-
sisting of spiral-wound modules with a total membrane
surface area of 135 m2 (Figure 3-22)
About 1.5 m3 of permeate are produced per hour (recyc-
ling water 2). The recycling water 2 is treated to such an
extent (see Table 3-4) that it can be used for rinsing pur-
poses in the main washing process. Thus the freshwater
demand is lowered.
With this multi-stage waste water treatment process, the
total recycling efficiency of the waste water volume flow
is approx. 70 %.
202
Figure 3-22
Nanofiltration plant at Textile Service Mewa
[photo: ENVIRO CHEMIE 2004]
Figure 3-21
Ultrafiltration plant at Textile Service Mewa
[photo: ENVIRO CHEMIE 2004]
Membrane Technology in Industrial Waste Water Treatment 3
3.5.8
Metal Processing Industry
In the metal processing industry, metal surfaces and also
non-metal surfaces (as far as they become metallized) are
treated by aqueous solution, emulsions, slimes, and also
fused salts (mechanically, chemically, electrochemically
and thermally). The various waste waters resulting from
these processes are mainly loaded with inorganic pollu-
tants and characterized by their high metal content. In
addition, they contain organic substances such as mine-
ral oils (especially found in cutting fluids), varnish com-
ponents, mineral greases, chlorinated hydrocarbons and
other solvents.
For the discharge of waste water from the metal industry,
Appendix 40 of the Waste Water Ordinance [ABWV 2002]
as well as the requirements of the municipal statutes and
the Ordinance on Indirect Discharges are valid. Compli-
ance with the limit values is only possible after internal
treatment of the process waste waters, otherwise they
have to be discharged as hazardous waste, which is rather
expensive.
Lowering the costs for discharge and raw material is the
primary motive of an enterprise to buy an internal pro-
cess- or waste water treatment plant which at the same
time contributes to protect the environment. A possible
solution to reduce the waste water quantity to be dis-
charged and, with this, the discharge costs is the treat-
ment, i. e. concentration of the liquid waste by membrane
filtration and vacuum evaporation [SPECHT 1997]. The
resulting permeate may be recycled and used again in the
process. If permeate and concentrate are completely re-
used, the process is waste-water-free. However, it is not
possible to achieve waste-water-free operation “off the
peg”, because treatment techniques as well as auxiliary
material used in production, e. g. cleaning agents, have
to be coordinated and adapted to the production facili-
ties [SPECHT 1997]. Comprehensive preliminary tests
help to avoid mistakes and to save costs.
203
COD mg/L 100
Conductivity µs/cm 500
Bacteria colony-forming units/mL 100
Table 3-4
Quality of the recycling water 2 [Enviro Chemie 2004]
Parameter Unit Concentration
Membrane Technology in Industrial Waste Water Treatment3
The Rasselstein Hoesch GmbH with its headquarters at
Andernach and production works at Andernach and Dort-
mund holds a top position among the European tinplate
producers. Tinplate is cold-rolled blackplate with a thick-
ness between 0.12 mm and max. 0.49 mm, which is main-
ly used as packaging material.
In the cold-rolling process, palm oil is used which has to
be removed before further processing by a degreasing
process. The waste water from this process is organically
loaded due to the palm oil. This waste and the waste
water from the cleaning of the degreasing facility, which
is necessary in regular intervals, and the new preparation
of the degreasing bath require considerable quantities of
degreasing agents.
These were the reasons for commissioning in 1999 an
ultrafiltration installation (Figure 3-23), in cooperation
with the company Membran-Filtrations-Technik-GmbH
(MFT). Ceramic tube modules working at an operating
pressure between 6 and 8 bar remove the palm oil from
the degreasing baths. The ultrafiltration membrane with
a surface area of 4.56 m2 processes a feed flow of 1 m3 per
hour. It is cleaned automatically after 120 hours (using at
first alkaline, then acid products, followed by backwash-
ing with water). The installation has been operating now
for 1.5 years (as of June 2001); the service life of the
membranes is expected to be five years.
The filtrate (about 90 % of the feed) is recycled as clean
degreasing solution directly into the bath, while the con-
centrate is fed to rolling grease treatment and afterwards
discharged thermally.
After some initial operating problems, the advantages of
the installation became evident: With constant process
bath quality, the waste water quantity is reduced thanks
to recirculation of 9 m3 per hour. In addition, drinking
water and chemicals are conserved. Also, the COD load is
reduced by 24 % and with this the discharge costs. Accord-
ing to calculations, the total investment of 358,000 Euro
will be amortized after 1.5 years.
204
Metal Processing Industry
Rasselstein Hoesch GmbH
Start-up
Objectives
Membrane surface area
Modules
Feed volume flow
Pretreatment
Benefit
1999
Reduction of the palm oil load in the waste water, i. e. the number of cleanings of the degreasing
facility and of new preparations of the degreasing baths are reduced
4.56 m2
Ceramic tube modules
1 m3/h (approx. 90 % of the feed are yielded as filtrate)
none
Saving of freshwater and chemicals, reduction of the waste water quantity and of the discharge costs
Membrane process Ultrafiltration
Figure 3-23
Ultrafiltration installation at the company
Rasselstein Hoesch [photo: MFT GMBH]
UF3.5.8.1
UF3.5.8.2
Membrane Technology in Industrial Waste Water Treatment 3
The flat plastic membranes with a molecular separation
size of 30.000 Dalton are wound on supporting structures
made from high-grade steel. The total filter surface area is
1.1 m2 and processes a filtrate flow of 0.3 m3 per hour, at
an operating pressure of 2 bar. The membranes are cleaned
twice a week and replaced after approx. 12 months. Since
the filtrate is recycled into the production process, only
the concentrate has to be discharged. With this operating
mode, the service life of the degreasing baths was extended
from two weeks to six months.
205
Metal Processing Industry
Faurecia, Bertrand Faure Sitztechnik GmbH & Co. KG
Figure 3-24
Ultrafiltration installation at the company Faure-
cia, Bertrand Faure Sitztechnik GmbH & Co. KG
[KASTEN 2001]
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Benefit
October 2000
Saving of costs by extension of the service life of the degreasing baths and ensuring of a constant product
quality
1.1 m2
Flat membranes wound on support structures made from high-grade steel
0.3 m3/h
Grease and oil separation
Saving of freshwater, waste water and degreasing chemicals as well as reduction of waste water levies
Membrane process Ultrafiltration
The company Faurecia Autositze GmbH & Co. KG has de-
veloped into an international business group which sup-
plies the car industry. Today the Faurecia group has about
100 works in 25 countries. In the works Stadthagen, about
800 employees produce metal fittings and seat components
(seat- and seat back frameworks) for the car industry.
Cathodic dip coating of the frameworks requires upstream
degreasing by special chemicals. The impurities removed
from the metal surfaces enter the degreasing bath and con-
tinuously reduce the cleaning efficiency, until the clean-
ing effect is no longer sufficient. At this stage, the degreas-
ing bath has to be replaced.
In order to save costs by prolongation of the service life
of the degreasing baths and to ensure a constant product
quality, the company Faurecia decided to use a process
combination with membrane technology. The waste water
from the degreasing of the seat frameworks is pretreated
in a tank in which fats and oils float, and heavy pollu-
tants as well as metal sludges are collected and separated
weekly via a special discharger. After a retention time of
three hours, the oil content in the oil-water mixture drops
to 0.2 %. The mixture is then fed to the ultrafiltration in-
stallation built by the company Atec Automatisierungs-
technik GmbH (Figure 3-24).
Since October 2000, the ultrafiltration installation sepa-
rates more oil quantities by means of a patent-protected
cross-flow process using agitators (Atec-Overflow-System).
Membrane Technology in Industrial Waste Water Treatment3
Besides its ecological advantages, the ultrafiltration in-
stallation provides also economic benefit by saving de-
greasing chemicals, water and waste water. The demand
for chemicals was reduced by 85 %, the water demand by
water-free, as it serves to recover iron and to oxidize chro-
mium. Thanks to this installation by the company Ato-
tech, the service life of the chromium baths is theoreti-
cally unlimited.
In membrane electrolysis, a transport of charged parti-
cles through ion-selective membranes as well as electrode
reactions such as reduction or oxidation take place (see
Figure 3-25).
The ion-selective membrane separates the anolyte (chro-
mic acid) from the catholyte (polycarboxylic acid). Only
the cations, e. g. metallic impurities, are able to pass the
membrane. Due to the potential applied, the cations are
transported through the membrane to the cathode where
they are reduced and separated as metal. At the same time
the chromium (Cr3+) reduced during the chromizing pro-
cess is oxidized at the anode (Cr6+) and recycled. Since
this oxidation process goes faster than the ion transport
to the cathode, only a very small part of the chromium
passes the membrane.
In the electroplating enterprise Rudolf Jatzke at Bielefeld-
Sennestadt, managed since 1979 by the owner Klaus
Wickbold, 14 employees work in the field of hard chro-
mium plating. The work pieces, partly special models for
customers from all branches, are protected by chromium-
plating against wear and corrosion. During this process,
metal cations, especially iron and chromium(III), are
removed by etching from the surface of the workpiece
and get into the electrolyte. This has negative effects on
the quality and requires continuous cleaning or regular
discharge and new preparation of the highly toxic solu-
tions.
Up to now, a cation exchanger had been used to treat the
solutions, resulting in large quantities of waste water with
a heavy-metal load whose discharge required again large
quantities of chemicals. For this reason a membrane elec-
trolysis installation (called chromium dialysator) has been
developed in cooperation with the University of Bielefeld
and later with the University and Polytechnic of Pader-
born, promoted by Deutsche Bundesstiftung Umwelt, Os-
nabrück. This plant has been operating since 1993 waste-
90 %, and the discharge costs were reduced by 90 %, so
that the installation will be amortized after less than two
years, according to the calculation of the person respon-
sible for surface- and environmental technology.
206
3.5.8.3
Metal Processing Industry
Electroplating Enterprise Rudolf Jatzke
Start-up
Objectives
Membrane surface area 1)
Modules
Permeate volume flow
Pretreatment
Benefit
1993
Extension of the service life of the electrolytic solution and reduction of the demand for chemicals
approx. 0.25 m2
2 cells per dialysator (standard)
no information
none
Saving of freshwater, reduction of the demand for chemicals, reduction of the heavy-metal sludge quantity
Membrane process Membrane electrolysis
1) The output of the chromium dialysator is not a function of the membrane surface area, but of the current quantity (the current density being the limiting
factor). If the current becomes too great, the membrane is destroyed.
Membrane Technology in Industrial Waste Water Treatment 3
Compared to the cation exchange installation used be-
fore, the yearly water de-mand is reduced by 28,000 m3
and the demand for chemicals by 25,000 kg. Only 750 kg
of harmless citric acid are used instead of 10,000 L of sul-
phuric acid. Also, 7.5 t of heavy-metal sludge are avoided.
Besides these environmentally relevant advantages, a re-
duction of the annual power consumption by 10 % results
from the conversion to continuous coating processes,
which also results in improved product quality.
In 1997, a European patent was issued for the membrane
electrolysis process. Membrane electrolysis is not only
applicable for chromium baths, but also for a large num-
ber of other processes (chromatizing, pickling).
In addition to the membrane electrolysis installation, the
company Jatzke is equipped with a computer-controlled
water cycle and vacuum evaporation system for the rins-
ing water. In 2000, the company Jatzke received the first
price of the Effizienz-Agentur NRW (EFA) for production-
integrated environmental protection.
207
anode
chromium bath (anolyt)
met
allic
po
lluti
on
s
cathode
membrane
Fe3+
Cu2+
Zn2+
Ni2+
(Cr3+)
Cr6+
Cr3+
Figure 3-25
Mode of operation of the electrolysis membrane
[SCHMIDT 2002]
UF3.5.8.4
Membrane Technology in Industrial Waste Water Treatment3
The works Langenberg of the Wieland-Werke AG is a cold-
rolling mill where 361 employees are occupied with the
processing of rough-rolled belts from copper and copper
alloys to finished high-grade products (including for the
electronics industry).
After each rolling process, the belts are given the neces-
sary characteristics in annealing installations and acid-
treatment plants. Afterwards the surface of the belts is
cleaned mechanically by brushing machines. In the past,
the waste water from these brushing machines (about
80 m3/h) was treated jointly with other process waste
waters by neutralisation, precipitation/flocculation and
gravel filtration. A partial flow was recycled into the pro-
cess. In this configuration, 46 m3/h of waste water still
have to be discharged into the public sewer system and
have to be replaced by freshwater from a river.
In 1998, a concept for water saving was realized in the
works Langenberg which had been tested before in detail.
This was done in cooperation with the company Dr.-Ing.
Peters Consulting für Membrantechnologie und Umwelt-
technik (CMU), Neuss, and der RWW Wassertechnologie
GmbH, Nettetal, and with a financial subsidy from the
Land Nord-Rhine Westphalia4). According to this concept,
the waste water from the brushing machines is treated by
ultrafiltration in dead-end mode, after having passed a
paper belt- and a cartridge filter. Each of the four brushing
machines integrated into this concept forms an internal
“local” water cycle with an ultrafiltration installation
(Figure 3-26). The capillary modules from X-Flow have a
total filter surface area of 44 m2 and produce up to 6 m2
of filtrate per hour, at a transmembrane pressure of up to
max. 1 bar. The filtrate is reused in the brushing machines.
The particle-containing water (0.5 m3/h per installation)
from backwashing of the ultrafiltration is fed into the
internal water cycle. With this, the water quantity in this
cycle as well as the freshwater demand and the consump-
tion of neutralization and precipitation agents is reduced
by 60 %. The resulting sludge, which contains copper, is
used in the iron and steel industry.
208
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Benefit
1998
Water saving
44 m2
Capillary modules
up to 6 m3/h
Paper belt-, cartridge filter
Saving of freshwater and reduction of the waste water quantity
Membrane process Ultrafiltration
Start-up
Objectives
Modules
Permeate volume flow
Pretreatment
Benefit
2001
Water savings
Cushion modules
approx. 24 m3/d
Ultrafiltration
Savings of completely demineralized water and reduction of the waste water quantity
Membrane process Reverse osmosis
4) Development program (1997-1999) “Action group for ecological and sustainable water management NRW“
RO
Metal Processing Industry, Wieland Werke AG
Figure 3-26
Ultrafiltration installation at the works Werk
Langenberg of Wieland Werke AG [MUNLV 2001]
Membrane Technology in Industrial Waste Water Treatment 3
After successful conclusion of a pilot test for the demine-
ralization of the filtrate from these ultrafiltration installa-
tions by low-pressure reverse osmosis, which was assisted
by ROCHEM UF-Systeme GmbH, Hamburg, and CMU,
Neuss, the water cycles at the brushing machines were
expanded in 2001 by corresponding RO installations.
These are equipped with the FM (flat membrane) module
(cushion module). The permeate is deionized as far as
possible so that completely deionized water, which is
very expensive, for the rewashing process can be saved.
The enterprise described above is the first cold-rolling
mill for non-ferrous metals which uses ultrafiltration in
dead-end operation and low-pressure reverse osmosis.
The use of these methods represents an improvement in
the state of the art for this field.
The environmentally relevant investments (229,800 Euro,
with a subsidy of the Land NRW of 100,000 Euro) are
profitable: Besides the waste water quantity which now is
only approx. 4 m3 per hour, the water consumption, too,
was clearly reduced (by up to 90 %) by internal recircula-
tion. Moreover, by ultrafiltration as well as low-pressure
reverse osmosis the particular and dissolved substances
are removed as far as possible from the individual water
cycles, so that the surfaces of the final products are of
constant high purity.
209
UF3.5.9.1
Membrane Technology in Industrial Waste Water Treatment3
In the DaimlerChrysler AG plant in Düsseldorf, 5,400
employees are occupied with the production of goods
vehicles. The car bodies are painted by applying three
layers, each applied in a separate process. The second
paint layer, the so-called filler, absorbs rockfalls and
equalizes small anomalies in the bodywork.
In former times, the filler was sprayed on the car body
using a pressure-driven manual system. With this proce-
dure, half of the paint ended up as “overspray” beside
the car body and had to be discharged at high costs as
flocculated and dewatered paint sludge.
By conversion of the painting process, the percentage of
overspray was clearly reduced. At the same time, a water-
soluble paint was used which is applied in a closed cycle
and a paint recycling process.
The recycling installation from the company Eisenmann
Lacktechnik KG for water-soluble paint has been in ope-
ration since 1998. The ultrafiltration installation is an
important component of the process along with prefiltra-
tion and chemical conditioning (Figure 3-27). Plate mod-
ules made of polymer membranes (company Rhodia)
separate the paint particles from the water phase at an
operating pressure of between 3.5 and 4.5 bar.
Depending on the solid matter content, the membrane
surface area of 30 m2 processes a permeate flow of 1,060
to 1,400 L/h. The membranes are backwashed after one
or two weeks and cleaned chemically once a year. 10 % of
the membrane surface area is replaced per year. The fil-
trate is used to improve the quality of the circulating
water in the system, while the concentrate is reused as
recycled paint for the painting of car bodies.
The use of membrane technology for paint recycling
shows that ecological advantages may also be of econo-
mic benefit. Thanks to reprocessing, about 30 tons of
210
3.5.9
Treatment of Waste Water from Car Painting
Treatment of Waste Water from Car Painting, DaimlerChrysler AG
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Benefit
1998
Reduction of the discharge costs for paint sludges
30 m2
Plate modules
1.0 – 1.4 m3/h
Prefiltration, chemical conditioning
Saving of paint, reduction of hauls because paint sludge is no longer produced
Membrane process Ultrafiltration
Figure 3-27
Ultrafiltration installation in the DaimlerChrysler
works at Düsseldorf [HARMEL 2001]
NF3.5.9.2
Membrane Technology in Industrial Waste Water Treatment 3
paint are saved per year. Moreover, the discharge of the
50 tons of paint sludge (70 % of this paint line) produced
up to now is no longer necessary, which means that dis-
posal costs are saved. Besides the environmentally rele-
vant aspects, these savings are so great that the invest-
ment of nearly 358,000 Euro will be amortized probably
after 3.5 years.
211
Treatment of Paint Waste Water from the Production of Spare Parts in the Ford Works, Cologne
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Benefit
2001
Recycling of valuable substances, Reuse of the permeate and the concentrate in the production process
No information
No information
~ 2 m3/h
Fine screen
Reduced fresh-water consumption, lower waste water loads, reduced chemicals cost, lower total costs
Membrane process Nanofiltration
concentrate for discharge
car components to be painted
UF NFRO UF
rinsing bathsrinsing bathsrinsing bathsdegreasing phospating
1st step: degreasing 2nd step: phospating 3rd step: painting
cathodicdipcoat
Figure 3-28
Flow sheet of paint-spraying [IMB + FRINGS WATERSYSTEMS GMBH 2004]
Membrane Technology in Industrial Waste Water Treatment3
212
After degreasing, the car components are phosphated and
then flushed. The process waste water from flushing have
been treated since 2001 by a nanofiltration plant. One
objective is the recycling of heavy metals and phosphates.
Thus, the concentrate is used as replenisher for phosphat-
ing. The permeate is used with additives to flush the car
components after degreasing. Approximately 2 m3/h of
process waste water is treated by the nanofiltration plant
(Figure 3-29). The service life of the membranes is approx.
3 years.
Thanks to the operation of the nanofiltration plant, fresh-
water and chemical consumption were lowered and the
waste water load was reduced. The total costs of the pro-
cess were lowered by 15 %.
The process concept presented above comprises as a final
step the recirculation of the anolyte in paint-spraying
(cathodic dipcoat) by single- or multistage reverse osmo-
sis and the prolongation of the service life of the dipcoat
bathes by treatment of the liquid by means of an ultrafil-
tration plant. The realization of these measures for further
reduction of the fresh-water and chemical demand is in
the planning stage.
Especially in the car industry it is useful to treat and to
recycle single process water flows because small volume
flows can be treated effectively and valuable substances
can be recovered. These valuable substances are found,
among other places, in the process water flows resulting
from the paint-spraying of car components.
The company imb+frings watersystems gmbH has devel-
oped in cooperation with Henkel Surface Technologies a
process concept for the recycling of water and valuable
substances from paint-spraying for the Ford works in
Cologne. The concept provides separate treatment for
each of the process water flows from degreasing, phos-
phating and paint-spraying (Figure 3-28). The treatment
of waste water from phosphating by nanofiltration
has been already implemented.
The process waste water from the degreasing bath for
cleaning of the car parts are treated by an ultrafiltration
plant. The permeate is used for flushing. Thus the fresh-
water and chemicals consumption can be reduced. The
concentrate is discharged as waste water.
Figure 3-29
Nanofiltration plant at the Ford works Cologne
[photo: IMB + FRINGS WATERSYSTEMS GMBH 2004]
UF3.5.10
Membrane Technology in Industrial Waste Water Treatment 3
The foundations for the company Schering were laid in
1851 by Ernst Schering who opened the “Green Pharma-
cy” in the north of Berlin. Today Schering AG employs
approx. 26,000 people in 140 subsidiaries in the develop-
ment and production of drugs as a main field of activity.
At the Bergkamen site, active agents are made as a basis
of drug production. Due to changing batch production,
the composition of the waste water varies depending on
the production process. Until 2003, the waste water was
temporarily stored after pretreatment in a mixing and
equalizing tank and then discharged into the nearby
municipal waste water treatment plant.
To ensure waste water treatment according to the state of
the art and satisfying the quality requirements of the re-
ceiving water body, Schering AG tested the possibility of
an industrial waste water pretreatment plant with mem-
brane bioreactor technology. This process turned out to
be economically end ecologically efficient. The membrane
installation, which is nationwide the largest for the treat-
ment of industrial waste water, has been in operation since
2003 (see Figure 3-30). Since 1st July 2004, the treated
waste water has been discharged directly.
The membrane bioreactor at the Bergkamen site treats on
average 3,500 m3 of waste water per day. Its composition
is presented in Table 3-5.
213
Pharmaceutical Industry, Schering
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Benefit
2003
Optimized waste water treatment according to the state of the art
15,840 m2
Cassettes/capillary membranes
~ 150 m3/h
Primary settling
Reduction of waste water disposal costs
Membrane process Ultrafiltration
Figure 3-30
Aerial photograph of the waste water treatment plant at Schering AG [photos: SCHERING AG 2004],
left: general view, right: side view of the membrane installation
Membrane Technology in Industrial Waste Water Treatment3
Figure 3-31 shows the flow sheet of the waste water treat-
ment. The first stage consists of to primary settling tanks
connected in series with a volume of 1,000 m3 each. They
serve to neutralize the waste water, to dose precipitants
and flocculants and to separate solids and precipitation
products.
The three-line activated sludge stage with a total volume
of 9,000 m3 is realized with upstream denitrification and
nitrification, followed by the membrane installation with
four lines. The membrane installation consists of 36 mem-
brane cassettes of the type ZW 500c from the company
ZENON (Figure 3-32). It has a total membrane surface
area of 15,840 m2. After membrane filtration, the treated
waste water is discharged into the receiving water.
214
Table 3-5
Inflow values, effluent requirements and operating values of the plant [SCHERING AG 2004]
Parameter Unit Inflow (mean values) Effluent requirements* Operating values
COD mg/l 3,500 > 90 % reduction compliance with the requirements
BOD5 mg/l 1,500 below detection limit
Ntot mg/l 95 < 50 mg/l compliance with the requirements
Ptot mg/l 8 < 2 mg/l compliance with the requirements
* according to Annex 22 of the Waste Water Ordinance
waste water
recirculation
membrane stage
nitri-fication
denitri-fication
waste waterbuffer tank
neutralisationand primarytreatment stage
emergencycatchbasin
excess sludge
sludgestorage
receivingwater
Figure 3-31
Flow sheet of the waste water treatment plant [according to SCHERING AG 2004]
Membrane Technology in Industrial Waste Water Treatment 3
Two aerated sludge storage tanks with a total volume of
1,700 m3 have been built to manage the excess sludge.
Three tanks with a total volume of 20,500 m3 are available
as emergency catch basins.
The investments for the new construction of the plant,
which mainly comprised the activated sludge tanks and
the membrane installation, were approx. 10 million Euro,
1.6 million Euro of which had been granted as funds by
the state North-Rhine Westphalia.
Besides gas and odour, landfill leachate is one of the main
emissions from landfills for municipal waste. During the
amendment of the Federal Water Act in 1986, it has been
defined for the first time as “waste water which has to be
treated” [HENSS, OPITZER 1995]. In general it is highly
polluted by organic and inorganic matter, and the load
may vary considerably over the life of the landfill.
Various processes and process combinations exist for the
treatment of landfill leachate [ATV 1993, VDMA 1994] to
produce a permeate which can be discharged without
restriction (Waste Water Ordinance, Appendix 51 [ABWV
2002]). Often a single process is not sufficient to achieve
the desired result.
During the last years, two process combinations for the
treatment and processing of landfill leachate have domi-
nated [PETERS 1996]:
• the combination of a biological stage and oxidation or
activated carbon (Figure 3-33) and
• the combination of reverse osmosis, high-pressure re-
verse osmosis; if necessary nanofiltration and discharge
of the residues.
Besides these process variations, others are also used, e. g.
the extension of the biological pretreatment stage (from
the first bullet) by an integrated membrane stage.
The reverse osmosis process belongs to the state of the
art in leachate treatment [ATV 1993]. Many years of con-
tinuous operation of numerous large-scale installations
prove that the organic and inorganic constituents present
in dissolved form in the leachate can be separated by 98 –
99 % with the help of reverse osmosis, at relatively low
expense, if modules and installation systems are adapted
215
3.5.11
Miscellaneous
3.5.11.1
Landfill Leachate
Figure 3-32
Optical inspection of a membrane module
[photo: SCHERING AG 2004]
Membrane Technology in Industrial Waste Water Treatment3
216
biological pretreatmentraw leachate membrane process
(reverse osmosis/nanofiltration)
oxidation
activated carbon
recycling
controlled infiltration into the landfill body,for a certain time and locally limited
incinerationevaporation
dryingintegration
elimination
residue
treated leachate
concentrate
gravel filterraw leachate
residue
treated leachate
nitrogenremoval
incineration
integration
nitrogencompound
residue
membrane process(reverse osmosis)
evaporation
activated carbon
controlled infiltration into the landfill body,for a certain time and locally limited
recycling
concentrate
elimination
Figure 3-34
Process combination according to the state of the art for the treatment of landfill leachate
using membrane processes with and without biological pretreatment
[completed according to ROSENWINKEL, BAUMGARTEN 1998]
carbon source
biological pretreatmentraw leachate
oxidation (ozon)
treated leachate
regeneration
activated carbon
energyexcess sludge
Figure 3-33
Process combination according to the state of the art for the treatment of landfill leachate
without using membrane processes [ROSENWINKEL, BAUMGARTEN 1998]
Membrane Technology in Industrial Waste Water Treatment 3
to the specific problem [PETERS 1998, PETERS 2000].
Operating results obtained with semi-industrial and large-
scale membrane installations for leachate treatment have
been documented and analyzed by BAUMGARTEN [1998].
Studies realized by THEILEN [2000] have shown that a
combination of conventional filtration (bag or cartridge
filter) and one or two membrane stages is very well suited
for the treatment of raw leachate. By means of a first mem-
brane stage (e. g. cushion or tube modules) and a second
stage which is possibly required (cushion or spiral-wound
modules), a permeate is produced from the high-loaded
leachate which has nearly surface water quality. Figure
3-34 presents process combinations for the treatment of
landfill leachate using membrane processes (reverse osmo-
sis, nanofiltration) with and without biological pretreat-
ment according to the state of art.
However, in leachate treatment, too, membrane processes
meet with their limits due to the development of irrevers-
ible covering layers. Since the leachate matrix is very
complex, these process limitations cannot be determined
on the basis of analytical results, but have to be deter-
mined onsite for each individual leachate [ROSENWINKEL,
BAUMGARTEN 1998].
Using membrane technology, there are three alternative
strategies for managing the leachate concentrates
[PETERS 2000]:
• incineration of the concentrate in installations which
are especially equipped and certified for the discharge
of high-loaded liquids,
• integration of the concentrate into various materials,
followed by deposition of the dry residues on the land-
fill,
• controlled infiltration of the concentrate into the land-
fill body (for a certain period and locally limited) in
order to improve the biochemical degradation process
of the organic waste and to accelerate the immobilisa-
tion of the organic material.
The third alternative leads to an increase of the gas pro-
duction and, with this, to accelerated reduction of the
organic material in a landfill. Comprehensive studies as
well as knowledge acquired from many years of experi-
ence confirm that over the long term no noticeable
changes in the leachate quality are observed [PETERS
2000].
217
Membrane Technology in Industrial Waste Water Treatment3
The company Abfallwirtschaft Kreis und Stadt Aachen
GmbH (AWA) (Waste Management for the District and
the City of Aachen) operates the central landfill Alsdorf-
Warden (commissioned in 1976), where only inorganic
waste is deposited. Within the scope of its capacity, the
central landfill also accepts inert material from external
corporations.
For leachate treatment, two installations are used. One of
them is a two-stage reverse osmosis installation which is
described in the following.
The two-stage reverse osmosis installation (Figure 3-35)
for leachate treatment is owned and operated since 1995
by the company Pall.
Both stages are equipped with so-called DT modules (disc
tube modules) from the company Pall. To protect the
installation, a gravel filter for the separation of coarse
matter and a cartridge filter are arranged upstream. The
installation comprises 60 modules in total, 44 of which
are used in the leachate stage, 13 in the first concentrate
stage (120 bar) and 3 in the second concentrate stage
(150 bar). Each module has a membrane surface area of
approx. 7.6 m2, so that a total membrane surface area of
about 460 m2 is available. At present, 5 m3 of leachate are
treated per hour, 92 – 95 % of which is yielded as per-
meate. The permeate is fed to the waste water treatment
plant, and the brine is discharged externally.
The membranes used are composite membranes with an
active layer from polyamide (Figure 3-36). Cleaning of
the membranes is required once or twice a week. Replace-
ment of the membrane has not yet been necessary since
starting up the installation.
Landfill leachate is treated exclusively for ecological rea-
sons. Thus the benefit of the two-stage reverse osmosis
system is ensuring environmentally oriented operation
and possible aftercare of the landfill.
218
Alsdorf-Warden Landfill
Start-up
Objectives
Membrane surfacee area
Modules
Permeate volume flow
Pretreatment
Benefit
1999
Treatment of the leachate, and thus protection of the landfill
approx. 460 m2
Disc tube modules
approx. 4.8 m3/h
Gravel filter for separation of coarse matter and gravel filter
Ensuring of the leachate treatment
Membrane process Two-stage: reverse osmosis, high-pressure reverse osmosis
Figure 3-35
Reverse osmosis installation at the landfill Alsdorf-
Warden [MAURER 2001]
RO3.5.11.1.1
ultra-thin active layerfrom modified polyamide
microporous intermediate layerfrom polysulfone
0,2 µm
supportingfabric frompolyester
40 µm
120 µm
Figure 3-36
Structure of the composite membrane [MAURER 2001]
Membrane Technology in Industrial Waste Water Treatment 3
In North-Rhine Westphalia there are many other sites
(e. g. Essen, Cologne, Mönchengladbach) where landfill
leachate is treated by membrane technology and biologi-
cal treatment or other processes (e. g. adsorption on acti-
vated carbon).
219
MF3.5.11.2
Membrane Technology in Industrial Waste Water Treatment3
Since the middle of the seventies, considerable efforts
have been made in the field of fresh-water aquaculture to
develop innovative, non-polluting and resource-conserv-
ing technologies for economic and environmentally
compatible intensive fish hatchery The development of
so-called closed-circuit plants was of special importance.
Since the middle of the nineties, the membrane bioreac-
tor technology has been available as an innovative pro-
cess for the realization of closed-circuit plants. The suita-
bility of this process for the treatment of waste water from
fish hatcheries was confirmed by studies with a pilot plant
membrane bioreactor (see Figure 3-37) that was installed
on the test facility of the Umweltbundesamt at Berlin-
Marienfelde.
The pilot plant consists of a tank for fish hatchery, which
is approx. 4 m high and made from fibreglass-reinforced
plastic, and the treatment plant. A pump feeds the water
together with the settled sediment (throughput: 1.7 L/s)
in intervals from the tank into the denitrification stage,
which consists of three PE tanks equipped with agitators.
The volume of the denitrification stage can be adjusted
to satisfy the requirements of the test operation by a ver-
tically adjustable overflow. Thus, the volume in the deni-
trification stage can be varied between 0.4 and 1.4 m3.
Nitrification takes place in the membrane stage with a
volume of approx. 1 m3. This tank contains the membrane
module consisting of 35 filter plates with a total filter
surface area of 21 m2. The pore size of the membranes is
0.4 µm. Below the filter module, air exhaust devices are
arranged which serve to clean the filter surface area and
to supply the sludge with oxygen. A second module exists
which can be used to double the filter surface area.
To ensure an internal sludge circuit between nitrification
and denitrification, the circulation pump feeds sludge
from the filter tank into the denitrification stage.
The permeate pump sucks the treated water through the
membranes and recycles it into the fish hatchery tank.
The pump operates constantly, apart from regular pauses
serving for better cleaning of the filter surface areas. The
water exchange rate for the fish hatchery tank is deter-
mined by the turn-on and pause times of the pump and
on the volume flow which can be chosen between 1 and
8 m3/d.
The excess sludge and the waste water flow from the fish
hatchery tank which is not recycled are discharged into
the waste water treatment plant.
The work up to market maturity is continued in a project
of Deutsche Bundesstiftung Umwelt (DBU) (German Fede-
ral Foundation Environment).
220
Fish Hatchery
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Benefit
2004, pilot plant
Reuse of the waste water / closure of water circuits
21 m2
One-decker plate modules
~ max. 8 m3/h
Not necessary
Savings of costs for fresh water and waste water discharge
Membrane process Microfiltration
UF3.5.11.3
Membrane Technology in Industrial Waste Water Treatment 3
The Dresden gas and steam turbine heating power station,
Nossener Brücke, was built in 1995. It has an electric out-
put of 270 MW, a thermal output of 455 MW of heating
water and 25 MW of steam. Since 1997 the power station
belongs to the DREWAG. In the middle of the operating
year 1996, turbine oil got into the long-winded and
branched intermediate cooling water system of the power
station. This free oil has deposited at different heat-ex-
changing surfaces which resulted in deterioration of the
heat transfer and thus of the cooling performance of in-
dividual pieces of equipment.
221
tank
membrane stagenitrification stage
recirculation
DN 1 DN 2 DN 3
denitrification stage
recycling flowfresh water
blowerinstallation
waste water totreatment plant excess sludge
Figure 3-37
Flow sheet of a circuit installation for the treatment of waste water from fish hatchery
[UMWELTBUNDESAMT 2004]
Power Stations, Dresden Gas and Steam Turbine Heating Power Station (GuD)
Start-up
Objectives
Membrane surface area
Modules
Filtrate volume flow
Pretreatment
Benefit
1996
Cleaning of oil-contaminated cooling water or heating circuits by separation of emulsified oil from the
circuit water by means of ultrafiltration
15.2 m2
Ceramic multichannel elements
Up to 2.5 m3/h
Cartridge filter < 1 µm
Rehabilitation of the cooling or heating capacity of oil-contaminated cooling or heating circuits
without downtimes of the power station
Membrane process Ultrafiltration
Membrane Technology in Industrial Waste Water Treatment3
Exchange of the cooling water quantity of approx. 90 m3
and flushing of the cooling water system would not have
been sufficient to clean the cooling system because it con-
sists of pipes of various diameters and different aggregates
with hydraulic dead zones. Alternatively, it would have
been necessary to change out all components of the pro-
cess equipment separately and to flush them. Besides the
expenditure for cleaning of the individual aggregates,
temporary shut-down of the power station would have
been required.
In order to solve the problem, a process was developed
jointly by the THERM-SERVICE für Kraftwerke und Indus-
trie GmbH and the DPC, Dr.-Ing. Peters Consulting für
Membrantechnologie und Umwelttechnik, using the
module technology of atech innovations GmbH. This
patented process was introduced under the designation
“RÖKU (Reinigung ölkontaminierter Kühlwasserkreisläu-
fe mit Ultrafiltration und Emulgierung bei laufendem
Blockbetrieb – Cleaning of oil-contaminated cooling
water circuits by ultrafiltration and emulsification at
running block operation)”. Compared to the conventional
procedure, the costs are lower and cost-intensive down-
times are avoided. Figure 3-38 shows the flow sheet of
the RÖKU process.
A RÖKU plant is conceived as a mobile unit and can be
adapted with high flexibility to the local condition. It
consists of the main components prefiltration, raw water
storage tank, ultrafiltration unit (Figure 3-39) with four
modules connected in series with 3.8 m3 of membrane
surface area each, circulation tank, filtrate tank, and a
CIP device for cleaning of the membranes.
In the case of the Dresden gas and steam turbine power
station, the oil sticking to the surfaces of the cooling wa-
ter circuit was emulsified with the help of a specifically
chosen emulsifier which was added to the cooling water.
This emulsion was treated by the ultrafiltration unit con-
nected in bypass. It is equipped with ceramic membranes
and operated in cross-flow mode. The treatment took
place in batches. The permeate, which still contained
part of the emulsifier, was recycled into the circuit. The
concentrate, in which the oil micro-droplets separated
from the emulsion, was discharged. In this way, about
1,600 L of oil were removed from the intermediate cool-
ing water circuit of the Dresden gas and steam turbine
heating power station. After having attained the desired
residual oil content, the emulsifier is removed from the
circuit water, which is accordingly conditioned.
222
cartridge filter
ultra-filtration
raw waterstorage
cooling watercirculation oil-loaded cooling water
circulationtank
permeatetank
oil discharge
cooling water without oil
concentrate
emulsifier
Figure 3-38
Flow sheet of the RÖKU process [according to DPC 1997]
UF3.5.11.4
Membrane Technology in Industrial Waste Water Treatment 3
Other examples for the use of this ultrafiltration-based
process were the rehabilitation in the heating power sta-
tion Zolling of Isar-Amper Works in 1997 (separation of
approx. 1,000 L of lubricating oil from the intermediate
cooling water circuit with a content of 300 m3) and in
1998 the cleaning of an intermediate cooling water cir-
cuit with a content of 130 m3 and 400 heating elements
in a hospital at Rottweil (removal of 2,600 L of lubricat-
ing oil).
Various types of oily residues result from navigation (in-
land or other navigation), which accumulate in the bilge,
the deepest place in the machine room of a ship. This
oily waste water, called bilge water, is a mixture of oil,
lubricating grease, fuel residues, cooling water, condensed
water, antifreeze and anticorrosive agents, cleaning agents,
as well as river or sea water in unknown concentrations
[FURTMANN ET AL. 2001]. Therefore, the bilge water has
to be pumped out periodically, i. e. the oil-water mixture
from the bilge has to be eliminated. In the past, the bilge
water was pumped out into a water body, but this has
been prohibited since 1963.
223
De-oiling of Bilge Water
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Benefit
1989
Discharge of bilge water
23.6 m2
Tube modules
3 m3/h
Oil separation
Saving of volume on the ship, contribution to environmental protection
Membrane process Ultrafiltration
Figure 3-39
Ultrafiltration unit for the RÖKU process
[photo: THERM-SERVICE]
Membrane Technology in Industrial Waste Water Treatment3
In order to ensure the discharge of the bilge waters, the
riparian Federal States of river Rhine have established in
1965 the Bilgenentwässerungsverband (bilge drainage as-
sociation). This is a corporation under public law, which
is under legal supervision of the Land North-Rhine West-
phalia. To fulfil its duties, the association makes use ot
the Bilgenentölungsgesellschaft mbH (bilge de-oiling
company), which accepts and treats the bilge water free
of charge from all ships (independent of their country of
origin).
The Bilgenentölungsgesellschaft mbH was established in
1961 and employs 25 people. It is responsible for bilge
de-oiling of all inland navigation ships in the Federal
Republic of Germany south of Münster. (For Hamburg,
Bremen and Berlin, other institutions have taken over
this task.) The company operates several bilge de-oiling
boats which separate the oil from the water phase by
gravity separators and, in addition, since 1989, by ultra-
filtration.
The bilge water is sucked off and preseparated by a cas-
cade oil separator (see Figure 3-40). The oil phase is col-
lected in a tank and, according to the water content,
reprocessed or submitted to thermal treatment. The ther-
mal treatment is performed by other companies.
The water phase is fed to an ultrafiltration system (from
the company Berghof) operated in cross-flow mode. Tube
modules with polymer membranes and a molecular sepa-
ration size of 100,000 Dalton separate more oil from the
water phase at an operating pressure of 7 bar. The total
membrane surface area (23.6 m2) produces 3.0 m3 of fil-
trate per hour, which according to the permission of the
responsible water authority complies with the limit
values and is discharged directly into a water body.
The concentrate is fed again to the ultrafiltration system
and is further concentrated. After several passes, only a
few litres of oil-containing concentrate are left which are
also collected in the oil tank and either reused or dis-
charged. Depending on their operation, the membranes
are backwashed once or twice a week. Practice has shown
that the service life of the membranes is about 15,000
operating hours.
224
ultrafiltration
concentrate
recirculation after closingthe influent
separator
permeate
sucking-offfrom the bilge
oil phase
collecting tank forused oil
water phase
deliveryashore
Figure 3-40
Flow sheet of bilge de-oiling [according to DEUTSCH 2001]
UF RO3.5.11.5.1
Membrane Technology in Industrial Waste Water Treatment 3
3.5.11.5
Swimming Pools
In swimming-pool water, in addition to small pollutants,
also water-soluble and emulsifiable substances (e. g. sweat,
residues of skin cream and suntan lotions) accumulate
and must not exceed certain concentrations. In usual
swimming-pool operation, this is managed by dilution
with drinking water which is pumped into the filled pool.
Due to this pumping and water displacement by bathing
people, water – splash water – flows off via the overflow
launder into a splash-water tank. After having passed a
conditioning facility, the filtered water is fed back into
the swimming-pool.
From time to time the filter has to be cleaned by back-
washing (mostly with splash water). The sludge water
from backwashing is collected and discharged into the
public sewer system.
Between 30 L [DIN 19643] and 120 L of water per guest
are consumed by discharge of water into the sewer sys-
tem and addition of fresh drinking water.
Due to water evaporation and refilling, the water hard-
ness, consisting of lime and magnesium salts, increases.
From chlorination and correction of the pH, other salts
develop. Moreover, big swimming-pool companies with
brine pools face the problem that brine is carried over to
the normal swimming-pool water.
Established in 1998, the city of Würselen is 100 % respon-
sible for this leisure facility with 30 employees.
In order to reduce the large freshwater quantities which
are necessary in conventional filtration, an ultrafiltration-
and reverse osmosis installation (degebran® GmbH Anla-
genbau) was planned and commissioned in 1998 in the
course of the new construction of Aquana Freizeitbad.
The plant is not integrated into the pool-water cycle, but
serves to recover about 70 % of the large water quantity
which is necessary for backwashing of the sand filters.
For this purpose, two membrane filtration stages operate
in series to treat sludge water (from filter backwashing),
shower water, water from washbasins and rainwater. In
addition they remove substances such as organic chlorine
compounds, washing and cleaning agents and urine com-
ponents (Figure 3-41). The membrane systems operate in
cross-flow mode. After prefiltration, back-washable capil-
lary membranes with a total filter surface area of 72 m2
separate in the first ultrafiltration stage solid pollutants
and suspended substances. From this filter cycle, 10 % of
concentrate is continuously withdrawn and discharged as
waste water. The filtrate is fed to the second stage, the
225
Swimming Pool, Aquana Freizeitbad GmbH & Co. KG
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Benefit
1998
Reduction of the freshwater quantities needed
42 m2 (UF), 140 m2 (RO)
Capillary modules (UF), spiral-wound modules (RO)
In total (UF and RO) 5 m3/h
Prefiltration
Saving of freshwater and energy for heating
Membrane processes Ultrafiltration (UF), Reverse osmosis (RO)
Membrane Technology in Industrial Waste Water Treatment3
reverse osmosis installation, where spiral-wound
modules (140 m2 filter surface area) also reject dissolved
substances. The permeate of this second stage is recycled
via activated-carbon adsorption into the swimming-pool
water cycle, while the brine, which contains more salts,
is used as process water. The total capacity of the system
is 5 m3 per hour.
Thanks to this process, up to 80 % of the freshwater
quantity used before, needed as filling water, is saved.
In addition the energy demand is reduced because it is
possible to recycle the permeate in warm state into the
pool cycle without additional heating. The amortization
period of the investment of 383,000 Euro is calculated at
three years.
226
ultrafiltration
concentrate
reverse osmosis
brine as processwater
filtrate
activated carbonadsorber sludge water
showerwaste
splash water tank
rainwaste
raw water
swimming-pool
normal operation filter backwashing
permeate
prefilter
clean water
overflowchannel
Figure 3-41
Water recirculation and treatment at the Aquana Freizeitbad [according to DEGEBRAN ®]
UF3.5.11.5.2
Membrane Technology in Industrial Waste Water Treatment 3
The Freizeitbad Copa Ca Backum (leisure facility) is oper-
ated by the Hertener Stadtwerken GmbH (municipal ser-
vices). With the objective to reduce the freshwater de-
mand and to ensure a hygienic water quality, the Herte-
ner Stadtwerke GmbH and the L.V.H.T.-Institut5), Essen
(scientific assistance) developed a process for the treat-
ment of waste waters from public swimming-pools and
commercial plants. Since August 1998, this process com-
bination, which includes membrane technology, has been
used in the Freizeitbad Copa Ca Backum for the treatment
of pool water, sludge water and shower water.
The used water from bathing and part of the shower water
are collected in a raw-water tank, where particulate sub-
stances settle and are separated by a screen (Figure 3-42).
The downstream ultrafiltration installation serves for
pre-liminary treatment of the combined process water.
Polymeric hollow-fibre membranes (Pall system) separate
in dead-end mode undissolved particles and turbidity as
well as oils, fats and ointments, so that only dissolved
substances are fed to the following process stages. In
total, the six modules with a filter surface area of 50 m2
each process a permeate volume of 10 m3 per hour.
To remove the developing covering layer from the mem-
brane, backwashing every half hour (by reversing the flow),
combined with air cleaning (hourly), is necessary. Che-
mical (alkaline) cleaning of the membranes is performed
every four weeks. With this operating mode, the service
life of the membranes is expected to be five years.
After additional treatment stages (oxidation as well as
adsorption on activated carbon and final disinfection
with chlorine), the filtrate has drinking water quality. It
is collected in a storage tank and used as pure water for
filling of the swimming pool or for filter backwashing.
The sludge water from filter backwashing is discharged
into the raw-water tank and flows together with the used
pool water and the shower water through the treatment
cycle described above. Water losses resulting from the
treatment and through evaporation or carry over in the
bath are compensated for by feeding freshwater.
Although freshwater is regularly fed, the salt content in
the swimming-pool water may increase by up to 10 – 15 %
in a year, due to recirculation of the backwashing water
and evaporation losses. But this is not relevant since ac-
cording to DIN 19643 the complete pool volume must be
exchanged once a year.
227
Swimming Pool, Freizeitbad Copa Ca Backum
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Aftertreatment
Benefit
August 1998
Reduction of the freshwater quantity needed and ensuring disinfected water
300 m2
Hollow-fibre membranes
10 m3/h
Sedimentation, particle separation by screening
Oxidation, adsorption, disinfection
Saving of freshwater and energy
Membrane process Ultrafiltration
5) L.V.H.T.- Lehr- und Versuchsgesellschaft für innovative Hygiene-Technik mbH, Institut für angewandte Bau- und Bäderhygiene GmbH, Essen
Membrane Technology in Industrial Waste Water Treatment3
In the process combination presented above, the mem-
brane technology is only employed as an upstream treat-
ment stage. The economic advantages, such as savings of
freshwater and energy, are therefore related to the whole
system. With adherence to freshwater savings of 60 %
and the forecasted energy savings of 50 %, the plant will
be amortized after approx. 3 – 5 years.
228
oxidationultrafiltrationfiltrate
final disinfection
swimming-pool
adsorption
raw water storage tanksludge water frombackwashing
sludge water
shower water
backwashing water
filling water
Figure 3-42
Water treatment at the Freizeitbad Copa Ca Backum [according to L. V. H. T. 2001]
Membrane Technology in Industrial Waste Water Treatment 3
229
3.6
Sample Applications of Plants Outside of Germany
The use of different membrane processes in Germany is
described in the subsections of chapter 3.5. The subsec-
tions of this chapter deal with examples from internatio-
nal practice. The examples are sorted in the same way as
in chapter 3.5 according to the branches of industry in
which the installations are used. All examples described
in the following are listed in Table 3-6.
Food industry
Chemical
industry
Food industry
Food industry
Malthouses
Laundries
Pharmaceutical
industry
Animal carcass
disposal
Mechanical-bio-
logical waste
treatment
Table 3-6
Sample applications for the use of membrane technology in industrial waste water treatment outside of
Germany
Branch of
industry
Kellogg
Raisio Chemicals
Dairygold
Dairy Crest
Sobelgra n. v.
Laundry Massop
Sandoz/
BIOCHEMIE
SARIA
Tirme
Company
Manchester
(Great Britain)
Veurne
(Belgium)
Mitchelstown
(Ireland)
Davidstow Camel-
ford Creamery
(Great Britain)
Antwerpen
(Belgium)
Kerkrade
(The Netherlands)
Barcelona
(Spain)
Bayet
(France)
Mallorca
(Spain)
Location
2004
2004
2000
2003
2004
1998
2003
2000
2004
Start-up
UF
UF
UF
UF
UF
RO
MF
UF
UF
Membrane
process
Tube modules
Immersed
rotating plate
modules
Tube modules
Tube modules
Immersed capil-
lary modules
Spiral-wound
modules
Immersed plate
modules
Immersed capil-
lary modules
Tube modules
Modules
5 � 216
1,188
648
486
8,000
250
1,440
1,800
100
3.6.1.1
3.6.1.2
3.6.1.3
3.6.1.4
3.6.1.5
3.6.2
3.6.3
3.6.4.1
3.6.4.3
ChapterMembrane sur-
face area m2
Membrane Technology in Industrial Waste Water Treatment3
3.6.1
Food Industry
Muesli Production at the Kellogg Company,
Great Britain
Depending on the production batch, the waste water
may contain solids which are removed by a rotary screen.
However, cocoa powder cannot be separated by sieving.
In this case, the waste water containing cocoa powder is
detected by turbidimetry and is subsequently fed into a
decanting centrifuge for the separation of solid matter.
The liquid phase is fed to the biological treatment stage
where the dissolved organic constituents are degraded.
The biological treatment stage is realized according to the
activated sludge process, combined with externally arrang-
ed ultrafiltration for biomass separation according to the
BIOMEMBRAT® process from Wehrle Umwelt GmbH.
The five-line ultrafiltration installation (Figure 3-44) is
operated in cross-flow mode. It produces 60 – 80 m3 of
permeate per hour. Depending on the waste water quantity,
the individual UF lines can be connected or disconnected.
The resulting excess sludge is mixed with the cocoa-
containing waste water in the aerated storage tank of the
decanting centrifuge. The solids are subsequently separated
in the decanting centrifuge and discharged.
Today the Kellogg Company has 25,000 employees in
19 countries who make more than 50 different cereal
products in 19 countries.
At the Manchester site, considerable quantities of flush-
ing water and waste water with different constituents
(corn components, cocoa, sugar etc.) result from the pro-
duction of muesli. Up to 2003, the waste water was only
treated by a curved screen to separate the solid matter.
The main reason for the planning of an efficient waste
water treatment plant in 2003 construction was the con-
tinuously increasing waste water fees. It was put into
operation in 2004.
For expansion of the waste water treatment plant, a pro-
cess was to be chosen which had a low demand for space
and was able to cope with highly variable pollution loads
and water quantities. Moreover, it should be expandable
with the ability to recycle the treated waste water. Figure
3-43 shows the flow sheet of the waste water treatment
plant.
230
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Benefit
2004
Compliance with the requirements for indirect discharge and reduction of the costs for waste water treatment
5 x 216 m2
Tube modules
60 – 80 m3/h
Rotary screen and decanting centrifuge
Reduction of the effluent charge, expandable waste water treatment plant with low space requirement
Membrane process Ultrafiltration
UF3.6.1.1
Membrane Technology in Industrial Waste Water Treatment 3
and the energy costs for activated sludge separation by
the cross-flow ultrafiltration membranes. On top of that
there are the costs for membrane replacement (membrane
exchange every four years is prognosticated) and the costs
for the application of membrane cleaning agents (chemi-
cal cleaning every 6 – 8 weeks, according to empirical
values from other installations).
The energy consumption of the biological stage depends
on the incoming COD load. The energy uptake of the ex-
ternal cross-flow ultrafiltration is a function of the
specific filtrate capacity. The possibility to connect indi-
vidual ultrafiltration lines depending on the waste water
quantity and an automatic control of the aeration devices
allows for an energy-saving operation mode of the waste
water treatment plant.
The investment for the membrane installation was
930,000 Euro. The operating costs for the external cross-
flow ultrafiltration system amount to 0.36 s/m3 of perme-
ate, for the biological stage they are 0.38 s/m3.
The costs for waste water treatment mainly consist of the
energy costs for aeration of the biological treatment stage
231
buffer tankactivated sludgetank
storage tankdecanter
decanter
liquid phase
solids
solids
rotary screen
turbidi-metry
ultrafiltration
feed
recirculation
receivingwater
Figure 3-43
Flow sheet of the waste water treatment plant at the Kellogg Company in Manchester
[according to WEHRLE UMWELT GMBH 2004]
Figure 3-44
Cross-flow ultrafiltration at the Kellog Company in
Manchester [photo: WEHRLE UMWELT GMBH 2004]
Membrane Technology in Industrial Waste Water Treatment3
Primary Starch Production at Raisio Chemicals, Belgium
At the site Veurne/Belgium, the Finnish company Raisio
Chemicals, which was taken over in March 2004 by Ciba
Spezialitätenchemie, makes primary starch products from
starch for the food industry, photographic industry and
the pharmaceutical industry.
The processing of the primary starch products requires
large amounts of fresh-water, so that a closed water circuit
would be useful for both economic and ecological reasons.
A waste water treatment plant suited for the site Veurne
had to be not only efficient but also compact due to re-
stricted space. Figure 3-45 shows the flow sheet of the
membrane bioreactor.
232
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Benefit
2004
Efficient and compact waste water treatment
1,188 m2
Immersed rotating plate membranes
Max. 12 m3/h
No mechanical pretreatment
Reduction of the fresh-water demand and of the waste water, reduction of costs
Membrane process Ultrafiltration
waste water
blowerinstallation
membrane system
waste watercollector
production
permeatetank
Figure 3-45
Flow sheet of the membrane bioreactor at Raisio Chemicals [according to HUBER AG 2004]
Figure 3-46
Huber VRM® process (rotating modules)
[photos: HUBER AG 2004]
UF3.6.1.2
UF3.6.1.3
process is the rotating plate membranes immersed in the
waste water. By the rotating membrane plates, combined
with air input, optimized covering layer removal can be
attained. The membrane installation can be expanded
with up to two additional plate membrane modules of
the type VRM® 20/252.The treated waste water is fed into
the production process via a permeate storage tank.
Membrane Technology in Industrial Waste Water Treatment 3
The process technology for the installation, which was
commissioned in 2004, consists of a mixing and com-
pensating tank, the membrane bioreactor and a permeate
storage tank. The waste water from the production is
homogenized and fed into the activated sludge stage
(V = 1,800 m3) in which two plate membrane modules of
the type VRM® 20/198 from the company Huber are
immersed (Figure 3-46). A special feature of the VRM®
Dairygold Food Products is one of the biggest and lead-
ing dairies in Europe, with its headquarters in Michels-
town, Ireland. Dairygold Food Products produces milk
powder, cheese and butter and runs a meat and sausage
factory. At the site in Michelstwon, 5,000 m3 of waste
water are produced per day which is treated by a conven-
tional activated sludge plant. During the milk season
from March to November the waste water volume increa-
ses to 7,000 m3/d, due to whey processing. The increase
of the waste water volume and of the COD load exceeded
the treatment capacity of the existing activated sludge
plant so that in the milk season the biological treatment
stage was overloaded, which resulted in an exceedance of
the effluent limits. This situation was the reason to study
the technical and economic efficiency of separate treat-
ment of the waste water from whey treatment (approx.
2,000 m3/d) by a membrane bioreactor. In 2000, a new
installation according to the BIOMEMBRAT® process
from the company Wehrle Umwelt GmbH was built.
The concept provides the operation of the membrane
installation during the summer months with higher
loads and its shutting-down in winter. During winter
time, the membrane modules are preserved and stored.
The required short start-up phase in the beginning of the
season is of special importance. Especially in times with
peak loads, the membrane installation contributes to a
considerable improvement in the effluent concentrations
of the whole waste water treatment plant. Figure 3-47
shows the flow sheet of the waste water treatment plant.
233
Dairygold Food Products, Ireland
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Benefit
2000
Compliance with the demands on the effluent quality during the milk season
648 m2
Tube modules
80 - 90 m3/h
Relief of the existing activated sludge plant, compliance with the effluent standards
Membrane process Ultrafiltration
Membrane Technology in Industrial Waste Water Treatment3
The membrane bioreactor consists of an upstream deni-
trification tank (V = 400 m3), a nitrification tank (V =
2,000 m3) and four lines of ultrafiltration, which are oper-
ated in cross-flow mode and serve to separate the biomass.
Each of the four ultrafiltration lines has a membrane
surface area of 162 m2. They can be connected or discon-
nected individually depending on the waste water quan-
tity. The membranes are tube modules with an inner dia-
meter of the tubes of 8 mm. The mean transmembrane
pressure difference in operation is 0.8 bar. The individual
ultrafiltration lines have to be cleaned chemically in inter-
vals of approx. 4 – 6 weeks to ensure a constant filtration
capacity. During the last four years the membranes have
not been replaced. A service life of 5 – 6 years is expected.
The COD inflow concentration of up to 3,600 mg/L
(2,600 mg/L on average) is reduced to 50 mg/L in the
effluent. The effluent requirements of BOD5 < 12 mg/L,
TKN < 15 mg/L and Ptot < 10 mg/l are reliably fulfilled.
234
denitrification andnitrification tank
clarifier
feed membrane stage
seasonalactivity
recirculation
sludge
recirculation
recirculation
denitrification andnitrification tank
receivingwater
Figure 3-47
Flow sheet of the waste water treatment plant at Dairygold Food Products, Ireland
[according to WEHRLE UMWELT GMBH 2004]
Figure 3-48
Complete plant at Dairygold Food Products with
the membrane installation in the foreground
[WEHRLE UMWELT GMBH 2004]
UF3.6.1.4
Membrane Technology in Industrial Waste Water Treatment 3
From 2000 to 2003, the specific energy consumption was
approx. 5kWh/m3 on average, approx. 2.8kWh/m3 of which
was used for ventilation and recirculation and 2.2 kWh/m3
for membrane filtration. The energy consumption of the
biological treatment stage mainly depends on the COD
and notrogen loads.
The energy demand of the ultrafiltration and the mem-
brane replacement costs make up approx. 23 % of the
total operating costs. The specific operating costs of the
overall membrane bioreactor are approx. 0.90 Euro per m3
of permeate. However, it must be taken into account that
the membrane installation only works about 7 months
per year. The investment for the membrane installation
was approx. 700,000 Euro.
235
Dairy Crest Limited, Great Britain
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Benefit
2003
Expansion of the capacity of the waste water treatment plant
486 m2
Tube modules
~ 50 m3/h
Flotation
Increase of the production capacity at the same site
Membrane process Ultrafiltration
The company Dairy Crest, one of the leading dairies in
England, has increased its production capacity in the
Davidstow Creamery at the site Camelford. This resulted
in an increase in the waste water volume and load. Since
the Dairy Crest waste water treatment plant had no cor-
responding reserve capacities, it had to be expanded. The
waste water treatment process concept used at Dairygold,
Ireland, has also been implemented at the site of the
company Dairy Crest.
The existing conventional activated sludge plant had two
lines. During expansion, one of these lines was replaced
with a BIOMEMBRAT® installation (Figure 3-49). In addi-
tion, a flotation process was arranged upstream of the
biological stage to separate grease and suspended matter
and thus relieve the downstream treatment stages.
After flotation, the waste water flow is divided. The daily
waste water flow is approx. 2,000 m3/d, 1,200 m3/d of
which are fed into the new membrane stage and 800 m3/d
into the existing conventional plant. The effluents of
both installations, operated in parallel, are then com-
bined and discharged into the receiving water. The three-
line membrane installation is equipped with tube mod-
ules with a membrane surface area of 162 m2 per line. It
is possible to expand the installation by a fourth line.
The BIOMEMBRAT® installation in the Davidstow Cream-
ery at the site Camelford is able to reduce the influent
COD load by approx. 98 %, and the Ntot and Ptot loads by
approx. 90 % each. The demands on the effluent of BOD5
< 10 mg/L and NH4-N < 6 mg/l are met with reliability.
The investment for the membrane installation was
550,000 Euro.
UF3.6.1.5
Membrane Technology in Industrial Waste Water Treatment3
236
recirculation
denitrification and nitrification tank
sludge
clarifier
receivingwater
membrane stage
buffer flotationprocess
feed
denitrification and nitrification tank
recirculation
Figure 3-49
Flow sheet of the waste water treatment at Dairy Crest, Great Britain
[according to WEHRLE UMWELT GMBH 2004]
Malthouse Sobelgra n. v., Belgium
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Benefit
2004
Compact, space-saving and efficient waste water treatment plant, pretreatment upstream of a planned
reverse osmosis installation
8,000 m2
Immersed capillary membrane modules
80 – 100 m3/h
Curved screen
Expansion of the waste water treatment capacity without extensive site construction. In future,
part of the treated waste water will be reused.
Membrane process Microfiltration
Membrane Technology in Industrial Waste Water Treatment 3
The Belgian malthouse Sobelgra is situated in the Antwer-
pen harbour and belongs to the multinational Boortmalt
group. Sobelgra produces malt for breweries and is at pre-
sent increasing its production capacity from 110,000 to
250,000 t/a. This means that the works will become the
biggest independent malthouse in Belgium.
Within the scope of production increase, the capacity of
the existing company-owned waste water treatment plant
had also to be doubled. Due to limited space at the facto-
ry site (Figure 3-50), it was impossible to expand the plant
according to the conventional activated sludge process.
The reasons to install the membrane bioreactor process
were its compact size and the high volume-specific degra-
dation capacity.
The company-owned waste water treatment plant treats
the waste water from barley processing by a combination
of mechanical presieving, biological stage and membrane
filtration (Figure 3-51).
After removal of coarse impurities by two curved screens
(mesh size: 1.0 mm), the waste water flows into the acti-
vated sludge stage, which consists of two tanks for deni-
trification and nitrification connected in series. The
membrane stage serving for separation of the biomass is
arranged downstream of the activated sludge stage. The
16 membrane modules from the company PURON AG
(Figure 3-52) have been installed in two separate cham-
bers. A third chamber is available for future expansion of
the plant (represented as dotted line in Figure 3-51). The
chambers are fed from below so that the waste water flows
upward through the membranes modules. The permeate
is withdrawn from the membrane modules by means of
negative pressure. The concentrated activated sludge is
recycled into the activated sludge tanks. The membrane
surface area in the immersed modules is 8,000 m3, it is
able to treat the entire waste water of the company. With
this, the installation has a capacity of more than 2,000m3/d.
To maintain the filtration capacity of the membrane mod-
ules, backwashing with filtrate takes place in regular
intervals, combined with air rinsing of the membrane
modules. The chambers can be emptied independently of
each other for cleaning and maintenance purposes.
About 80 % of the treated waste water will be reused in
the production process after installation of the planned
reverse osmosis installation.
237
Figure 3-50
Aerial photograph of the malthouse Sobelgra in
the Antwerpen harbour [photo: PURON AG]
feed
recirculation
blowerinstallation
sieve bend 1.0 mmbiological reactor
membrane stage
recycling
sieve bend 1.0 mm
Figure 3-51
Flow sheet of the company-owned waste water treatment plant of the company Sobelgra
[according to PURON AG]
Membrane Technology in Industrial Waste Water Treatment3
238
Figure 3-52
Schematic representation of the membrane bioreactor (left) and membrane modules (right)
[photo: PURON AG]
RO3.6.2
Membrane Technology in Industrial Waste Water Treatment 3
Laundry Massop, The Netherlands
The waste water passes an (integrated) two-stage filter
(fluff screen), before it flows into the reverse osmosis in-
stallation, which is equipped with spiral-wound modules
from polyethylene membranes. With a membrane surface
area of 250 m2 and at an operating pressure of 10 bar, the
permeate flow is approx. 8 m3 per hour. The permeate is
reused as washing water. The brine is discharged into the
public sewer system.
The membranes are backwashed once a day and cleaned
with commercial chemicals every third month. Practical
operation has shown that under these circumstances the
service life of the membranes is two years.
The following example illustrates the employment of
membrane technology for the treatment of waste water
from laundries. The installation described is used in a
laundry in The Netherlands and is similar to two installa-
tions which will be commissioned in the near future in a
laundry at Lemgo and another one at Olsberg. The reali-
zation of these projects is supported by funds from a
development program6) of the Ministry for Environment
and Nature Conservation, Agriculture and Consumer Pro-
tection (MUNLV) of the Land North-Rhine Westphalia.
The company Massop at Kerkrade cleans laundry from
hospitals and hotels. The waste water from washing is
loaded with contaminants, surfactants, bacteria and salts,
so that it has to treated.
The reason for the employment of a membrane installa-
tion was the possibility to save water and energy. When
planning the installation, it was especially important to
consider the close interaction between the membrane
and the detergent applied. For parallel development of
the reverse osmosis (Figure 3-53) and the suitable deter-
gent, the company Henkel-Ecolab GmbH & Co. OHG
(production of detergents and washing agents) coopera-
ted with the company Wientjens, NL. The installation
has operated successfully since 1998 and treats the water
to a sufficient quality for reuse in the washing process.
239
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Benefit
1998
Conservation of water and energy
approx. 250 m2
Spiral-wound modules
8 m3/h
Integrated two-stage filter (fluff screen)
Saving of freshwater, energy and chemicals
Membrane process Reverse osmosis
6) Development program for production-integrated environmental protection: “Action group for ecological and sustainable water management NRW”
Figure 3-53
Reverse osmosis installation at the laundry Massop,
Kerkrade [ROTH 2001]
MF3.6.3
Membrane Technology in Industrial Waste Water Treatment3
The employment of reverse osmosis for waste water treat-
ment and the reutilization of the treated water as process
water offer ecological and economic advantages. Besides
reduced detergent consumption, water (80%), energy (50%)
and softening chemicals (80 %) are also saved. The instal-
lation at Kerkrade is leased, which is profitable for the
operator. The amortization period of such an installation
may vary depending on the location and the general con-
ditions, thus it has to be determined for each single case.
With approx. 13,000 employees all over the world, the
company Sandoz (formerly company Biochemie) works
in the fields of development and production of pharma-
ceutical, biopharmaceutical and industrial products. In
Barcelona, the company Sandoz makes penicillin for the
production of medicine.
Up to now, the waste water generated from the produc-
tion process at the site in Barcelona was treated by con-
ventional processes. The quality of the treated waste
water strongly varied. Moreover, an increase in the pro-
duction volume at Barcelona was planned which requir-
ed an expansion of the company-owned waste water
treatment plant. Since an expansion with conventional
process engineering was impossible because of limited
space, it was decided to build a membrane bioreactor.
The installation was commissioned in February 2003.
Within the scope of pilot tests at the site Kundl of the
company Sandoz, the membrane bioreactor process using
immersed plate membranes from the company Kubota
was compared to other membrane systems at the site of
the company Sandoz (formerly company Biochemie) and
implemented as a large-scale installation already in 1999.
The waste water treatment plant at Kundl was expanded
in 2002 to a membrane surface area of 1,440 m2.
Based on the experience acquired at Kundl and on account
of the comparable boundary conditions, the membrane
bioreactor at Barcelona was equipped with a membrane
surface area of 1,440 m2 without further pilot tests. Figure
3-54 shows the flow sheet of the membrane bioreactor at
the site Barcelona.
The development and employment of membrane proces-
ses for the treatment of laundry waste water is currently
being pursued intensely. Besides the described process,
there are other membrane solutions for the treatment of
laundry waste water that are being developed. In plann-
ing, it is critical to consider the interaction between the
membrane and the detergent applied, so that cooperation
between installation- or membrane manufacturer and the
detergent producer is imperative.
240
Pharmaceutical Industry,
Penicillin Production at the Company Sandoz/Biochemistry, Spain
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Benefit
2003
Expansion of the waste water treatment capacity at the site of the company-owned WWTP
1,440 m2
Immersed plate membranes
~ 400 m3/d
Protection of the site when increasing the production volume
Membrane process Microfiltration
Membrane Technology in Industrial Waste Water Treatment 3
After treatment in the existing high-load biological stage
with 3 reactors of 500 m3 each, the waste water volume
of approx. 400 m3/d flows into the membrane separation
stage. For operation of the membrane installation, the TS
content in the activated sludge tanks was increased from
approx. 6 g/L to 12 – 16 g/L. With this, the biological de-
gradation capacity of the waste water treatment plant is
approximately doubled. The two-line membrane instal-
lation consists of 6 plate membrane packages from the
company Kubota of the type EK 300. Filtering takes place
at a constant transmembrane pressure of 0.05 – 0.15 bar.
Chemical in-situ cleaning is done automatically twice a
year. The permeate is discharged into a municipal waste
water treatment plant for further treatment.
241
membrane stage
feed
biological reactor
1
2
3
recirculation
blowerinstallation
blowerinstallation
receivingwater
Figure 3-54
Flow sheet of the membrane bioreactor in Barcelona [according to AGGERWASSER GMBH 2004]
Figure 3-55
Membrane bioreactor and membrane modules under construction at the company Sandoz in Spain
[photos: AGGERWASSER GMBH 2004]
Membrane Technology in Industrial Waste Water Treatment3
3.6.4
Miscellaneous
Animal Carcass Disposal Plant of SARIA
Bio-Industries, France
The company SARIA Bio-Industries operates in Bayet, in
Central France, an aminal carcass disposal plant. Up to
240,000 t of slaughterhouse waste and perished animals
are processed per year at this site. About 1,100 m3 of pro-
duction waste water with a mean COD concentration of
16,000 mg/L are produced per day. Due to increasing de-
mands on the effluent quality and increasing operational
capacity, the waste water treatment plant at the site of
the animal carcass disposal plant at the site Bayet had to
be adapted to the state of the art.
The decision-maker of the animal carcass disposal plant
chose in 2000 to convert the existing waste water treat-
ment plant to a membrane bioreactor. After successful
two-year operation, the installation was expanded already
in 2002.
The individual waste water flows from the animal carcass
plant are pretreated in part by flotation, treated mechani-
cally by a fine screen and homogenized in a mixing and
storage tank. The pretreated waste water is pumped into
an activated sludge tank (V = 4,000 m3) where the orga-
nic substances are degraded (Figure 3-56). The activated
sludge flows through a curved screen with a mesh size of
750 µm to protect the membranes from coarse matter
before it is fed in free overflow into the membrane stage.
The membrane stage is realized with four lines (Figure
3-57). Each line is integrated in a filtration container and
contains capillary membrane modules from the company
ZENON (Figure 3-58). At present approx. 1,800 m3 of mem-
brane surface area are installed. The first membrane line
consists of four immersed modules of the type 500a, the
second line has two immersed modules of the type 500c.
By treatment of the waste water in the membrane biore-
actor it is possible to attain COD effluent concentrations
of < 300 mg/L. Thus, the COD load in the installation is
reduced by 98 %.
242
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Benefit
2000, expansion in 2002
Compliance with increasing effluent standards and adaptation to capacity enlargement
1,800 m2
Immersed capillary membrane modules
~ 40 - 50 m3/h
Fine screen
Economic expansion and adaptation of the waste water treatment plant to the state of the art
Membrane process Ultrafiltration
UF3.6.4.1
Membrane Technology in Industrial Waste Water Treatment 3
243
feed
biological reactor4.000 m3
fine sieve750 µm
recirculation
blowerinstallation
membrane stage
blowerinstallation
receivingwater
Figure 3-56
Flow sheet of the membrane bioreactor at SARIA Bio-Industries in Bayet
[according to ZENON GMBH 2004]
Figure 3-57
General view of the membrane bioreactor of the
animal carcass disposal plant in Bayet
[photo: ZENON GMBH 2004]
Figure 3-58
Container with fitted modules at SARIA Bio-Indus-
tries in Bayet [photo: ZENON GMBH 2004]
membrane containers
Membrane Technology in Industrial Waste Water Treatment3
3.6.4.2
Mechanical-Biological Waste Treatment Plant
Mechanical-biological waste treatment has become es-
tablished in Europe as a concept for the treatment of
municipal waste. Biological conversion can take place in
composting plants (aerobically) or in fermentation plants
(anaerobically). Biological conversion in mechanical-bio-
logical waste treatment plants aims at biodegradation of
the organic constituents to reduce the waste volume and
to get a stabilized final product. From biodegradation
and dewatering results complex, high-loaded waste water.
Depending on the treatment process, approximately half
of the treated solid waste results as waste water which
needs treatment. The composition of the waste water
mainly depends on the raw solid waste (water content,
organic part) and on the fermentation process (wet, dry).
The concentrations of the individual parameters may
strongly vary. In principle, intensive conversion during
fermentation means higher pollutant concentrations in
the process waste water.
244
Waste Disposal at the Company TIRME, Spain
Start-up
Objectives
Membrane surface area
Modules
Permeate volume flow
Pretreatment
Benefit
2004
Closed production water circuit
100 m2
Tube modules
5 – 6 m3/h
Fine screen
Savings of freshwater and waste water
Membrane process Ultrafiltration
Besides a waste incineration plant, the company TIRME
also runs a plant for material separation and mechanical-
biological waste treatment at Mallorca. At this site, approx.
45,000 m3 of high-strength waste water are produced an-
nually which mainly comes from the mechanical-biologi-
cal waste treatment plant. Additional waste water result
from the cleaning of yards and vehicles and from the treat-
ment of waste air. The complex waste water composition
requires a combination of treatment processes. At first
the solids have to be removed from the waste water.
For mechanical-biological waste treatment, nitrogen-free
process water is required. The new waste water treatment
plant installed by the company Wehrle Umwelt GmbH
treats the waste water to such an extent that part of it can
be used after treatment for this purpose. The installation
consists of a mechanical pretreatment stage, an activated
sludge stage and an ultrafiltration installation (Figure 3-59).
The plant is designed for a throughput of approx.
45,000 m3/a or 140 m3/d of waste water with a COD con-
centration of 7,300 mg/L and a NH4-N concentration of
2,500 mg/L. The effluent COD concentration has to be
below 1,500 mg/L, which corresponds to a reduction of
approx. 80 %. Ammonium is completely degraded in
order to reuse the treated waste water as process water in
the mechanical-biological waste treatment plant.
UF3.6.4.2.1
Membrane Technology in Industrial Waste Water Treatment 3
Mechanical pretreatment of the waste water takes place
by settling with subsequent filtration by a fine sieve with
a separation size of 200 µm. After mechanical treatment,
the waste water flows into the activated sludge stage
which consists of upstream denitrification with following
nitrification (Figure 3-60). The activated sludge is separat-
ed in the downstream two-line ultrafiltration stage
(Figure 3-60). The filtration lines consist of four tube
modules each which can be operated and cleaned inde-
pendently of each other. The membranes are operated in
cross-flow mode with a mean transmembrane pressure of
approx. 4 bar and a flow velocity of 5 m/s. The total mem-
brane surface area is approx. 100 m2. The excess sludge is
discharged via the biological stage of the mechanical-bio-
logical waste treatment plant.
245
feed
recirculation
ultrafiltration
fine screen200 µm
nitri-fication
denitri-fication
activated sludge tank
ultrafiltration
to mechanical-biological waste watertreatment
excesssludge
receivingwater
Figure 3-59
Flow sheet of the waste water treatment plant at the company TIRME, Spain
[according to WEHRLE UMWELT GMBH 2004]
Figure 3-60
Waste water treatment plant at the company TIRME [photos: WEHRLE UMWELT GMBH 2004],
left: membrane installation, right: bioreactors
Membrane Technology in Industrial Waste Water Treatment3
246
Instructions and Standards
in Membrane Technology
4
Instructions and Standards in Membrane Technology4
As shown in the preceding chapters, the fields of applica-
tion of membrane technology for waste water treatment
and the objectives pursued are manifold (see chapter 3.2).
The utilisation of a membrane installation has to be exa-
mined for each single case and must be adapted to the
specific task. This explains the lack of DIN standards and
the small number of existing instructions. There are no
standard solutions for the use of membrane technology
and for the design of a membrane installation. However,
for some applications it is possible to fall back on the
experience acquired to-date.
The demands on the construction of membrane installa-
tions are defined in the instructions for plant construc-
tion. The design of installations with a certain capacity
and the demands on the membrane depend on the defi-
ned aim and on the boundary conditions.
The primary aim in waste water treatment consists of the
compliance with limit values which are defined in the
conditions for discharge into water bodies [ABWV 2002]
and into the public sewer system (Ordinances on Indirect
Discharge of the federal states and stipulations in the
articles of associations). They are based on § 7a of the
Federal Water Act [WHG 1996]. To be able to comply
with these limit values, advisory leaflets give recommen-
dations for the treatment of the characteristic emissions
of single industrial branches. In some advisory leaflets,
the utilization of membrane processes is also mentioned,
e. g. for the treatment of emissions from the metal-wor-
king industry [ATV-DVWK 2000b]. However, they con-
tain no design instructions.
DWA has established two expert committees concerning
the subject “membrane technology in waste water treat-
ment“: the Expert Committee KA-7 „Membrane biore-
actor process“ and the Working Group IG-5.5 “Membrane
technology“.
The expert committee mentioned first has already pub-
lished two work reports “Membrane bioreactor process“
[ATV-DVWK 2000a; DWA 2005]. The reports deal with
the basics of the membrane bioreactor process, design
approaches and necessary pretreatment measures. The
design approaches are not related to the design of the
membrane used, but to the change in dimensioning the
activated sludge tank compared to the conventional acti-
vated sludge process. The change results from the possibly
higher dry matter content. It mainly consists of another
calculation approach for the excess sludge production
and the oxygen consumption as well as in the definition
of a minimum sludge age and a minimum excess sludge
production.
The DWA Working Group IG 5.5 „Membrane technology“
has elaborated a work report with the title “Treatment of
industrial waste water and process water by the membrane
bioreactor process“ [ATV-DVWK 2002]. This work report
consists of two parts. Part 1 deals with the membrane
process for the separation of undissolved, colloidal or dis-
solved substances. Part 2 addresses the membrane bioreac-
tor process. It indicates in particular the differences which
result from the application of the membrane bioreactor
process for the treatment of industrial waste water com-
pared to municipal waste water. Due to the great variety
of application cases and the differences between the
waste waters, these work reports cannot contain design
instructions. But they give information on suitable or
unsuitable applications and list examples.
Additional instructions dealing with the utilization of
membrane technology in water and waste water treat-
ment are described briefly described in the following.
The Verband Deutscher Maschinen- und Anlagenbau e. V.
(Association of the German Mechanical Engineering and
Plant Construction) has published a standard sheet con-
cerning the application of membrane technology in the
treatment of landfill leachate [VDMA 1994]. This standard
sheet is to be seen as a provisional instruction which can
be used during consultations on the standardization or
preciseness of European standards. It contains qualitative
information on the design of membrane installations.
Not only the parameters to be determined are mentioned
(necessary membrane surface area, quantitative evaluation
of the volume flows for permeate and brine/concentrate),
but also the necessary planning steps (laboratory tests,
pilot installation and on-site tests in technical scale, see
also chapter 3.3). It is emphasized in particular that values
known from practice or determined by tests should be
used to determine the operating parameters (e. g. operating
pressure, overflow velocity, process temperature, specific
248
Instructions and Standards in Membrane Technology 4
permeate flow), examining thoroughly the boundary con-
ditions under which these values have been determined
[VDMA 1994]. This procedure for the planning of mem-
brane installations can be transferred to all other fields of
application.
In addition, the working group „Membrane technology“
of the Bundesvereinigung der Firmen im Gas und Wasser-
fach e. V. (FIGAWA) (Federal Association of the Companies
of the Gas and Water Branch) has published some advi-
sory leaflets and Technical Information on membrane
technology in water and waste water treatment. In differ-
ent releases, electrochemical desalination [FIGAWA 1999],
reverse osmosis [FIGAWA 1996a; FIGAWA 1996b; FIGAWA
1985], cross-flow microfiltration [FIGAWA 1992], electro-
dialysis and diffusion dialysis [FIGAWA 1991] and mem-
brane processes (RO, UF, elektrodialysis) in freshwater and
waste water treatment [MARQUARDT 1988] are explained.
Besides the mode of functioning of the respective process,
the Technical Information and advisory leaflets also men-
tion the fields of application. However, concrete design
instructions are not given.
249
1) FIGAWA: independent technical-scientific expert association, established in 1926. Its main task is the promotion of technology and science in the field
of gas and water. The working group „Membrane technology“ was founded in 1975 within the specialist group „Water treatment“. It accompanies the
development of rules and standards in this field as well as the technical development of the corresponding plants and equipment [FIGAWA 1999].
Instructions and Standards in Membrane Technology4
250
Summary and Outlook 5
Summary and Outlook5
Membrane technology currently represents a proven alter-
native to classical processes for many applications in
municipal and industrial waste water treatment and may
contribute to reduce the costs for water supply and waste
water disposal, production costs and environmental pol-
lution. This publication gives an introduction to mem-
brane technology and its application in municipal and
industrial waste water treatment in Germany according to
the state of the art. Applicability and capacity of membrane
installations are illustrated with examples of large-scale
installation realized on a municipal and industrial level.
The share of membrane installations used on a municipal
level worldwide is still small due to economic aspects,
concerning especially membrane replacement and energy
demand. Under some boundary conditions, the use of
membrane processes in municipal waste water treatment
may turn out to be economical, e. g. in the case of more
stringent or additional demands on the effluent quality,
limitations in space for new construction or expansion of
plants and possible reuse of the treated waste water.
The utilisation of low-pressure processes has shown that
waste water treatment by membrane technology with high
biomass concentration in the activated sludge tank may
be technically feasible and profitable. The investment for
a modern conventional plant and the investment for a
membrane bioreactor currently are of the same order of
magnitude. However, the operating costs of a membrane
installation are a little higher. To reduce these costs,
which also make a membrane bioreactor compete with a
conventional plant under economic aspects, research and
development have to focus on the increase of the permea-
te flow, the reduction of the specific energy consumption
and the prolongation of the service life of membranes.
In contrast to the municipal field of application, the use
of membrane technology in industry is common and pro-
ven by a large number of references. In industrial waste
water treatment, the use of membrane technology is often
associated with production-integrated environmental pro-
tection (PIUS). Since water is the solvent used most, PIUS
aims at avoiding the partly dissolved substances or, if this
is impossible, to separate them from the water and thus
to make a closed water circuit possible. Even if the water
circuit cannot be completely closed, the waste water
quantity may be reduced significantly by skillful multiple
use of the water.
Besides the examples presented in this publication, there
are other fields of application for membrane technology.
Thanks to the availability of different membranes and
modules, it is possible to find for nearly each task a tech-
nically suited system, which then has to be examined
under economical and ecological aspects. An exact inven-
tory of the existing boundary conditions and an econo-
mic analysis in comparison to alternative processes
should precede the choice, independent of the field of
application of a membrane process. However, it must be
emphasized that in most cases no standard solution
exists, so that in each case detailed planning and pilot
tests by experts, considering the existing boundary condi-
tions, are necessary for successful operation of a membrane
installation. Tests in laboratory and semi-technical scale
contribute to plan a safe and practical system. Special
attention should be paid to the demand for energy and
cleaning chemicals as well as to the service life of the
membranes. Increasing water and waste water costs and
decreasing membrane prices lead to continuous improve-
ment of the economic situation of membrane processes
compared to other waste water treatment processes.
The development of membrane technology in the field of
water and waste water treatment has not yet ended. In
future, a still broader range of applications can be expect-
ed. By continuous development of membrane materials
and module constructions as well as process design and
process engineering, it will be possible to solve problems
for which, in the past, membrane processes were not suit-
ed due to the characteristic of the liquid to be treated.
Therefore it is important to always observe and examine
new developments, besides the assessment of working
plants. There is still need for research in the field of plant
design, operating parameters and in the control of fouling
effects.
252
References 6
References6
A3 GmbH (2004): Information and photos from the
company A3-Abfall-Abwasser-Anlagentechnik GmbH,
Gelsenkirchen.
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Peters, T. (1996): Reinigung von Deponiesickerwasser
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Peters, T. (2000): Kontrollierte Infiltration von Sicker-
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Vulkan-Verlag, Essen.
Peters, T. (2001): personal information, Neuss.
Pieracci, J.; Crivello, J. V.; Belfort, G. (1998):
Photochemical modification of 10 kD polyethersulfone
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PURON AG (2003): personal information from Mr. Dr.
Voßenkaul and photos from the company PURON AG,
Aachen.
Quaiser, J. (2001): personal information, photos from
Enviro-Chemie GmbH, Roßdorf.
Rautenbach, R. (1997): Membranverfahren – Grund-
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Rautenbach, R.; Voßenkaul, K.; Melin, T. (2000):
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Resch, H. (2002): Information on planning data of the
Monheim waste water treatment plant, personal informa-
tion, January 2002, Weißenburg.
Rochem UF (2004): personal information and photos
from the company Rochem UF-Systeme GmbH, Hamburg
Roest, H. van der (2001): Membranbioreaktor-Techno-
logie beim Einsatz zur Reinigung kommunaler Abwässer.
In: Melin, T.; Dohmann, M. (Hrsg.): Begleitband zur
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Rosenwinkel, K.-H.; Gigerl, T.; Baumgarten, G.
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Beachtung der Möglichkeiten zur Konzentratentsorgung,
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Roth (2001): personal information, photos of the mem-
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RP Tübingen (2004): personal information from
Mr. Vogel, Regierungspräsidium Tübingen.
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Schering AG (2004): personal information from Mr.
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Bergkamen.
Schirm (2001): personal information, Eltmann.
Schilling, S. (2001): Einsatz eines Membranverfahrens
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4. Aachener Tagung „Membrantechnik“, IVT und ISA
RWTH Aachen.
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Schmidt, R. (2002): personal information, documents
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Stadt Dormagen (2004): personal information from
Mr. Wedowski, City of Dormagen.
Stadtwerke Schramberg (2004): personal informa-
tion from Mr. Rosenboom and photos from the Schram-
berg Municipal Utilities, Schramberg.
Starr, M. P., Stolp, H., Trüper, H. G., Balows, A.
(1981): The Prokaryotes, Vol. 1 and Vol. 2., Springer
Verlag, Berlin.
Stein, S. (2002a): Information on planning data of the
Markranstädt, Knautnaundorf and Markkleeberg waste
water treatment plants, personal information, January
2002, Leipzig.
Stein, S. (2002b): Information on the failure (autumn
2001) at the Knautnaundorf waste water treatment plant,
personal information, June 2002, Leipzig.
Stein, S.; Walther, H.; Zastrow, P. (2001): Kläranlage
Markranstädt – Betriebsergebnisse einer Membranbele-
bungsanlage. In: Melin, T.; Dohmann, M. (Hrsg.): Begleit-
band zur 4. Aachener Tagung „Membrantechnik“, IVT
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Flandern (Belgien), Korrespondenz Abwasser, Jg. 51, Nr. 7,
S. 754 – 759.
VA TECH WABAG (2002): personal information and
photos of the installation on the Transeuropa; Fotograf:
Ulrich Metelmann.
261
References6
VDMA (Verband Deutscher Maschinen- und
Anlagebau e. V.) (1994): Anlagen zur Reinigung von
Deponiesickerwasser, VDMA-Einheitsblatt 24439,
October 1994.
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year 2000. URL: www.vdp-online.de.
Verbandsgemeinde Bondorf (2004): personal infor-
mation from Mr. Vogel, Regierungspräsidium Tübingen.
Voßenkaul, K.; Melin, T.; Rautenbach, R. (2000):
Perspektiven der Membrantechnik im Wasserkreislauf
Schwimmbad. In: Melin, T.; Rautenbach, R.; Dohmann,
M. (Hrsg.): Begleitband zur 3. Aachener Tagung „Membran-
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Textilfärberei, Korrespondenz Abwasser, Jg. 47, Nr. 9,
S. 1296 – 1305.
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technik im regionalen Abwasserentsorgungskonzept,
Korrespondenz Abwasser, Jg. 48, Nr. 8, S. 1092 – 1097.
Wehrle Umwelt GmbH (2004): personal information
from Mr. Wienands and photos from the company Wehrle
Umwelt GmbH, Emmendingen.
WHG (1996): Gesetz zur Ordnung des Wasserhaushalts
– Wasserhaushaltsgesetz, Fassung vom 12. November 1996,
BGBl I, S. 1690.
Weise Water Systems GmbH (2004): personal infor-
mation from Mr. Weise and photos from the company
Weise Water Systems GmbH, Langgöns-Oberkleen.
Wozniak, T.; Baumgarten, S. (2001): Zweijährige
Betriebserfahrungen mit der Membrantechnik auf der
Kläranlage Büchel. In: Melin, T.; Dohmann, M. (Hrsg.):
Begleitband zur 4. Aachener Tagung „Membrantechnik“,
IVT und ISA RWTH Aachen.
Wozniak, T. (2002): personal information, among
others on the failure at the Swanage waste water treat-
ment plant, June 2002.
WVER (2004): personal information from Mr. Rolfs,
Wasserverband Eifel-Rur, Düren.
ZENON (2002): several information from the company
ZENON, Hilden.
ZENON GmbH (2004): several information from the
company ZENON GmbH, Hilden.
ZKR – Zentralkommission für die Rheinschiff-
fahrt (2000): Übereinkommen über die Sammlung,
Abgabe und Annahme von Abfällen in der Rhein- und
Binnenschifffahrt vom 9. September 1996; Straßburg
2000.
262
Annex A
AnnexA
A.1
Addresses (mentioned in the concrete examples)
A.1.1
Locations of the membrane systems in Germany
Municipal waste water treatment
WWTP Büchel
WWTP Seelscheid
WWTP Kaarst
WWTP Rödingen
WWTP Glessen
WWTP Knautnaundorf
WWTP Markranstädt
WWTP Simmerath
WWTP Konzen
WWTP Rurberg-Woffelsbach
WWTP Geiselbullach
WWTP Monheim
Aggerverband
Postfach 340240
51624 Gummersbach
Mr. Dr. Scheuer
www.aggerverband.de
Erftverband
Paffendorfer Weg 42
50126 Bergheim
Mr. N. Engelhardt
Ms. K. Drensla
www.erftverband.de
KW Leipzig GmbH
Johannisgasse 7
04103 Leipzig
Ms. S. Stein
www.wasser-leipzig.de
Wasserverband Eifel Rur
Eisenbahnstraße 5
52325 Düren
Mr. T. Rolfs
www.wver.de
Amperverband
Verwaltung Eichenau
Bahnhofstraße 7
82223 Eichenau
Mr. T. Kopmann
www.amperverband.de
Stadt Monheim
Marktplatz 23
86653 Monheim
Mr. Wild
www.monheim.de
WWTP Schramberg-
Waldmössingen
WWTP Xanten-Vynen
WWTP Eitorf
WWTP Kohlfurth
WWTP Merklingen
WWTP Richtheim
Stadtwerke Schramberg
GmbH & Co. KG
Am Hammergraben 8
78713 Schramberg
Mr. Rosenbohm
www.stadtwerke-schramberg.de
Linksniederrheinische Entwässe-
rungs-Genossenschaft (LINEG)
Friedrich-Heinrich-Allee 64
47475 Kamp-Lintfort
Mr. Dr. Kühn
www.lineg.de
Gemeindewerke Eitorf
Ver- und Entsorgungsbetriebe
Auf dem Erlenberg 3
53783 Eitorf
Mr. Neulen
www.eitorf.de
Wupperverband
Untere Lichtenplatz Straße 100
42289 Wuppertal
Mr. Dr. Erbe
www.wupperverband.de
Gemeinde Merklingen
Hauptstraße 31
89188 Merklingen
Gemeinde Ursensollen
Rathausstraße 1
92289 Ursensollen
www.ursensollen.de
264
Annex A
265
Municipal waste water treatment (Continuation)
WWTP Hailfingen
WWTP Dormagen
WWTP Piene
Abwasserzweckverband
Bondorf-Hailfingen
Rathaus
Marktplatz 18
72108 Rottenburg am Neckar
Stadt Dormagen
Stadtentwässerung
Tiefbauamt
Mathias-Giesen-Straße 11
41540 Dormagen
Stadtwerke Gummersbach
Rathausplatz 1
51643 Gummersbach
Mr. Bock
WWTP Golf Course St. Wendel
German Armed Forces
Stadt St. Wendel
Rathaus IV, Abwasserwerk
Marienstraße 1
66606 St. Wendel
Mr. Schmidt
Bundesamt für Wehrtechnik
und Beschaffung
Ferdinand-Sauerbruch-Straße 1
56073 Koblenz
www.bwb.org
Industrial waste water treatment
Food industry
Malthouse
Potato starch production
Emsland Stärke GmbH
Emslandstr. 58, 49824 Emlichheim
Mr. Dr. M. Lotz
www.emsland-staerke.de
“Deutsche See” GmbH & Co. KG
BEECK Feinkost GmbH & Co. KG
Albert-Schweitzer-Ring 35
22045 Hamburg
Mr. L. Diederichs
www.beeck-feinkost.de
Mälzerei Heinrich Durst
Malzfabriken GmbH & Co. KG,
Betrieb Gernsheim
Mainzer Staße 15 – 16
64579 Gernsheim
Mr. M. Filip
www.durst-malz.de
Branch CompanyBranch Company
Printing industry
Paper mills
Fibre industry
Grafische Handelsvertretung
Peter Leis
Mühlweg 32
35606 Solms
Mr. P. Leis
Papierfabrik Palm
Werk Eltmann
Industriestraße 23
97483 Eltmann
Mr. R. Schirm
www.wellenwunder.de/
palm-gruppe/main.htm
Vulkanfiber Ernst Krüger
GmbH & Co. KG
Postfach 1262, 47592 Geldern
Nordwall 39, 47608 Geldern
Mr. Dr. M. Joseph
www.hornex.de
AnnexA
266
Industrial waste water treatment (Continuation)
Textile industry
Plastics industry
Laundry
Gerhard van Clewe
GmbH & Co. KG
Loikumer Straße 10
46499 Hamminkeln-Dingden
Mr. A. van Clewe
www.van-clewe.de/vanclewe.html
Drews Meerane GmbH
Äußere Crimmitschauer Straße 80,
08393 Meerane
Mr. Ellmer
www.drews-meerane.de
Pongs Textil GmbH
Boschstraße 2
48703 Stadtlohn
Mr. Wening
www.pongs.de
HT Troplast AG
TROSIFOL
Mülheimer Straße 26
53840 Troisdorf
Mr. U. Offermann
www.ht-troplast.de
Rentex Fortex B. V.
Locatie Massop
Grisenstraat 5
NL-6465 CE Kerkrade
Mr. P. Massop
www.fortex.nl
ALSCO Berufskleidungs-Service
GmbH
Niederlassung Kaiserslautern
Otto-Hahn-Straße 1
67661 Kaiserslautern
Mr. Winter
www.alsco.de
Branch CompanyBranch Company
Laundry (Continuation)
Metal-working industry
Paint processing
Textilservice MEWA GmbH
Hermann-Gebauer-Straße 1
15831 Groß Kienitz
Mr. Lehmann
www.mewa.de
Rasselstein GmbH
Koblenzer Straße 141
56626 Andernach
Ms. Dr. S. Arnold
www.rasselstein-hoesch.de/
deutsch/index.htm
Faurecia Autositze
GmbH & Co. KG
Werk Stadthagen
Industriestraße 3
31655 Stadthagen Ort
Mr. K. Kasten
www.faurecia.com
Wieland Werke AG
Werk Langenberg
Ziegeleiweg 20
42555 Velbert
Mr. H.-U. Koböcken
www.wieland.de
Galvanik Rudolf Jatzke
Edisonstraße 7
33689 Bielefeld
Mr. K. Wickbold
DaimlerChrysler AG
Werk Düsseldorf
Ratherstraße 51
40467 Düsseldorf
Mr. T. Bergmann
www.daimlerchrysler.com
Annex A
267
Industrial waste water treatment (Continuation)
Branch CompanyBranch Company
Paint processing (Continuation)
Pharmaceutical industry
Power stations
Landfill leachate
Deoiling of bilge water
Ford-Werke GmbH
Henry-Ford-Straße 1
50725 Köln
Mr. S. Baumeister
www.ford.de
Schering AG
Ernst-Schering-Straße 14
59192 Bergkamen
Mr. Dr. Neuhaus
DREWAG
Gas- und Dampfturbinen
Heizkraftwerk Dresden
Rosenstraße 32
01065 Dresden
www.drewag.de
Abfallwirtschaft Kreis und Stadt
Aachen (AWA) GmbH
Deponie Alsdorf-Warden
Postfach 1459
52243 Eschweiler
Mr. R. Koch
www.awa-gmbh.de
Bilgenentölungsgesellschaft mbH
August-Hirsch-Straße 3
47119 Duisburg
Mr. R. Deutsch
www.bilgenentoelung.de
Swimming pools
Fish hatchery
Aquana Freizeitbad
GmbH & Co. KG
Willy-Brandt-Ring 100
52146 Würselen
Mr. M. Dovermann
www.aquana.de
Hertener Stadtwerke GmbH
Schwimmbad COPA CA BACKUM
Herner Straße 21
45699 Herten
Mr. H. Kuhlmann
www.freizeitbad.de/deutschland/
copacabackum.html
Freizeitbad Bergische Sonne
GmbH & Co.
Lichtscheider Straße 90
42285 Wuppertal
Mr. G. Geier
www.bergische-sonne.de
Umweltbundesamt
Fachgebiet III 3.5
Postfach 33 00 22
14191 Berlin
Mr. Dr. Pluta
www.umweltbundesamt.de
AnnexA
A.1.2
Planners and manufacturers of installations,
membrane manufacturers, Consulting Engineers
A large number of planners and manufacturers of installa-
tions, membrane manufacturers and consulting engineers
are working in the field of membrane technology. Even for
Germany, it is hardly impossible to draw up a complete
list, partly due to high fluctuations in this branch. There-
fore, in the following only the addresses of those com-
panies and offices are listed which have been specially
mentioned in the previous chapters and have contributed
information, e. g. for the concrete examples. Thus, this
selection does not claim to be complete. Additional
sources of information and important institutions in
connection with the subject membrane technology are
compiled subsequently.
268
A3-Abfall-Abwasser-
Anlagentechnik GmbH
Aggerwasser GmbH
ACO Passavant GmbH
Altenburger Elektronic GmbH
amafilter Deutschland GmbH
ATEC Automatisierungstechnik
GmbH
atech innovations GmbH
Magdeburger Straße 16 b
45881 Gelsenkirchen
Mr. U. Brüss
www.3a-gmbh.de
AV Aggerwasser GmbH
Sonnenstraße 40
51645 Gummersbach
www.aggerwasser.de
Ulsterstraße 3
D-36269 Phillipsthal
www.aco-passavant.de
Schlossweg 2 – 5
77960 Seelbach
Mr. Dr. S. Siegfried
www.altenburger.de/index.html
Am Pferdemarkt 11
30853 Langenhagen
Mr. Dr. G. Baumgarten
www.amafilter.com
Emmi-Noether-Straße 6
89231 Neu-Ulm
Mr. G. Enderle
www.atec-nu.de
Am Wiesenbusch 26
45966 Gladbeck
Mr. P. Bolduan
www.atech.daw.com
ATEMIS GmbH
Atotech Deutschland GmbH
Berghof Filtrations- und
Anlagentechnik GmbH & Co. KG
BKT Burggräf GmbH
BUSSE GmbH
CSM Filtrationssysteme
GmbH & Co. KG
degebran GmbH Anlagenbau
Dennewartstraße 25 – 27
52068 Aachen
www.atemis.net
Industriestraße 69, 90537 Feucht
Postfach 12 40, 90532 Feucht
Mr. Dr. R. Schmidt
www.atotech.com
Harretstraße 1
72800 Eningen
Mr. H.-U. Roth
www.berghof.com
Zum alten Zollhaus 20 – 22
42281 Wuppertal
Mr. H. Burggräf
Zaucheweg 6
047316 Leipzig
Mr. R.-P. Busse, Mr. C. Belz
www.busse-gmbh.de
Gewerbestraße 32
75015 Bretten-Gölshausen
Mr. R. Verschaeve
www.guthgroup.de
Resser Straße 65
44653 Herne
Mr. K. Paulus, Mr. H.- J. Krein
www.degebran.de
Annex A
269
DHV Water BV
Dr. Dahlem –
Beratende Ingenieure
Earth-Tech GmbH
Eisenmann Lacktechnik KG
EnviCare
ENVIRO-CHEMIE
Abwassertechnik GmbH
Erftverband
Fraunhofer IGB
Henkel-Ecolab GmbH & Co. OHG
Hese Umwelt GmbH/A3 GmbH
Postbus 484
3800 AL Amersfort
Mr. H. F. van der Roest
www.dhv.nl
Bonsiepen 7
45136 Essen
www.drdahlem.de
Forumstraße 24
41468 Neuss
www.axeljohnson.de
Heinrich-Hertz-Straße 8
74351 Besigheim-Ottmarsheim
Mr. E. Neubauer
www.eisenmann.de
Wittekeweg 9
A-8010 Graz
www.envicare.at
In den Leppsteinswiesen 9
64380 Roßdorf
Mr. J. Quaiser
www.enviro-chemie.de
Paffendorfer Weg 42
50126 Bergheim
www.erftverband.de
Nobelstraße 12
70569 Stuttgart
Henkel-Ecolab Deutschland
Reisholzer Werftstraße 38 – 42
40554 Düsseldorf
Mr. R. Krack
www.ecolab.de
Magdeburger Straße 16 a
45881 Gelsenkirchen
www.hese-umwelt.de
Hans Huber AG
Hydro-Ingenieure GmbH
HST-Systemtechnik
iat-Ingenieurberatung für
Abwassertechnik GmbH
inge AG
Ingenieurbüro Dr. Resch
imb + frings water systems gmbh
I-T-G GmbH, Ingenieurgemein-
schaft für Umwelttechnologie
ItN Nanovation
Keppel Seghers Belgium NV
Maschinen- und Anlagenbau
Maria-Hilf-Straße 3 – 5
92334 Berching
Mr. Dr. O. Christ
www.huber.de
Stockkampstraße 10
40477 Düsseldorf
www.hydro-ingenieure.de
Sophienweg 3
59872 Meschede
www.systemtechnik.net
Taubenheimstraße 69
70372 Stuttgart
www.iat-stuttgart.de
Flurstraße 17
86926 Greifenberg
Mr. M. Hank
www.inge-ag.de
Lehenwiesenweg 31
91781 Weißenburg
Mr. Dr. H. Resch
Horbeller Straße 15
50858 Köln
Mr. Dr. J. Lindemann
www.imbfrings.de
Buchenstraße 24
72810 Gomaringen
Ms. J. Knödler
www.itg-gmbh.de
Untertürkheimer Straße 25
66117 Saarbrücken
www.itn-nanovation.de
Hoofd 1
B-2830 Willebroek
www.segherskeppel.com
AnnexA
270
Klapp-Müller GmbH,
Ingenieurbüro für Umwelt-
und Bautechnik
KOCH-GLITSCH GmbH
KOCH Membrane Systems
GmbH
Krüger-Wabag
(see Veolia Water)
Kubota
L. V. H. T.
Mall GmbH
Martin Systems AG
Rehwinkel 15
51580 Reichshof
Mr. Dr. S. Schilling
www.klapp-mueller.de
Membrane Systems Divisions
Neusser Straße 33
40219 Düsseldorf
Mr. J. Hadler
www.kochmembrane.com
Krantzstraße 7, Eingang D
52070 Aachen
Mr. Dr. S. Schäfer
www.puron.de
Baumeisterallee 13 – 15
04442 Zwenkau
Standort Ratingen
Lise-Meitner-Straße 4a
40878 Ratingen
www.wabag.com
Under licence Aggerwasser GmbH
Lehr- und Versuchsgesellschaft für
innovative Hygiene-Technik mbH
Am Zehnthof 191a
45307 Essen
Mr. Dr. D. Pacik
www.lvht.de
Hüfingerstraße 39– 45
78166 Donaueschingen
Mr. S. Klemens
www.mallbeton.de
Ackerstaße 40
96515 Sonnenberg
Mr. M. Grigo
www.martin-systems.de
Memcor Australia
(see Siemens AG)
Memtec
Membrain
MDS Prozesstechnik GmbH
MFT
MICRODYN-NADIR
Filtration GmbH
NERAtec AG
NORIT N. V.
OSMONICS
40 Blackman Crescent
South Windsor, NSW 2576
Mergenthalerallee 45 – 47
65760 Eschborn
Mr. Baur
Contact: ZENON GmbH
Bahnhofstraße 315
47447 Moers
Mr. Dr. D. Böttger
www.mds-prozesstechnik.com
Membran-Filtrations-Technik GmbH
Eupener Straße 150
50933 Köln
Mr. H.-U. Hübbel
www.mft-koeln.de
Kalle Albert Industriepark
Rheingaustraße 190
65174 Wiesbaden
Mr. W. Ruppricht
www.microdyn-nadir.de
Max-Planck-Straße 7b
52249 Eschweiler
Mr. U. Kolbe
www.neratec.de
P. O. Box 89
7620 AB Borne
The Netherlands
www.norit.com
230, rue Robert Schumann
Z. A. des Uselles
B. P. 85
F-77350 Le Mee sur Seine
France
www.osmonics.com
Annex A
271
Pall GmbH
PURON AG
Dr.-Ing. Peters Consulting
(CMU)
ROCHEM UF-Systeme GmbH
Rhodia
RWW Wassertechnologie GmbH
Schwander GmbH
Siemens AG Water Technologies
TAMI Deutschland GmbH
Pall GmbH
Philipp-Reis-Straße 6,
63303 Dreieich
Mr. Dr. H. Eipper, Mr. C. Maurer
www.pall.com
refer to KOCH Membrane Systems
GmbH
www.puron.de
Dr.-Ing. Peters Consulting für
Membrantechnologie und
Umwelttechnik
Broichstraße 91
41462 Neuss
Mr. Dr. T. A. Peters
Stadthausbrücke 1 – 3
Fleethof
20355 Hamburg
www.rochemuf.com
Stadelstraße 10
60595 Frankfurt
Mr. Hoffmann, Mr. Linz
www.rhodia.com
Heinrich-Haanenstraße 6
41334 Nettetal-Lobberich
Mr. B. Lang
www.rww-wt.de
Theodor-Heuss-Straße 38
61118 Bad Vilbel
Mr. Dr. T. Jäger
www.schwander.de
Nonnendammallee 101
13569 Berlin
www.siemens.com/water
Heinrich-Hertz-Strasse 2/4
07629 Hermsdorf
Mr. B. Ruschel
www.tami-industries.com
Toray Deutschland GmbH
Tuttahs & Meyer
Ingenieurgesellschaft
US-FilterMEMCOR Products
(see Siemens AG)
VA TECH WABAG AG
Veolia Water Deutschland GmbH
WEHRLE-WERK AG
Weise Water Systems
GmbH & Co. KG
Wientjens b. v.
X-Flow B. V.
(see NORIT N. V.)
ZENON GmbH
Hugenottenallee 175
63263 Neu-Isenburg
Bismarckstrasse 2 – 8
52066 Aachen
www.tuttahs-meyer.de
441 Main Streel
Sturbridge, MA 01566
www.usfilter.com
VA TECH WABAG
Siemensstraße 89
1210 Vienna
www.vatechwabag.com
Unter den Linden 21
10117 Berlin
www.veoliawater.de
Bismarckstraße 1 – 11
79312 Emmendingen
Mr. G. Streif
www.wehrle-werk.de
Steinbruchstraße 6b
35428 Langgöns
www.weise-water-systems.com
Im Sprokkelveld 9
NL-6596 DH Milsbeek
www.wientjens.com
Bedrijvenpark Twente 289
NL-7602 KK Almelo
Mr. B. Brocades Zaalberg
www.xflow.nl
Nikolaus-Otto-Straße 4
40721 Hilden
Mr. H. Möslang
www.zenonenv.com
MUNLV
(Ministry for Environment and
Nature Conservation, Agriculture
and Consumer Protection of the
state North-Rhine Westphalia)
LUA NRW
(Environmental Office of the
state North-Rhine Westphalia)
EFA NRW
(Efficiency Agency North-Rhine
Westphalia)
BEW
(Training centre for waste water
and waste disposal and water
management)
DGMT
(German Association for
Membrane Technology)
Forschungsinstitut für Wasser-
und Abfallwirtschaft an der
RWTH Aachen (FiW) e. V.
(Research Institute for Water
and Waste Management at the
RWTH Aachen University)
Ministerium für Umwelt und
Naturschutz, Landwirtschaft und
Verbraucherschutz des Landes
Nordrhein-Westfalen
40190 Düsseldorf
www.munlv.nrw.de
Landesumweltamt
Nordrhein-Westfalen
Wallneyer Staße 6
45133 Essen
www.lua.nrw.de
Effizienz-Agentur NRW
Mülheimer Straße 100
47057 Duisburg
www.efanrw.de
Bildungszentrum für die
Entsorgungs- und Wasser-
wirtschaft GmbH
Bildungsstätte Essen
Wimberstraße 1
45239 Essen
www.bew.de
Deutsche Gesellschaft für
Membrantechnik e. V.
Eupener Straße 150
50933 Köln
www.dgmt.org
Mies-van-der-Rohe-Straße 17
52056 Aachen
Ms. M. Lange
Mr. Dr. F.-W. Bolle
Mr. J. Schunicht
www.fiw.rwth-aachen.de
Institut für Siedlungswasserwirt-
schaft der RWTH Aachen (ISA)
(Institute of Environmental
Engineering of the RWTH
Aachen University)
Experts, consultants
Mies-van-der-Rohe-Straße 1
52056 Aachen
Mr. S. Baumgarten
Mr. Dr. S. Köster
Univ. Prof. Dr.-Ing. J. Pinnekamp
www.isa.rwth-aachen.de
Prof. Dr.- Ing. P. Cornel
(Head of the work group IG-5.5
“Membrane technology“ of ATV-
DVWK or DWA respectively)
Technische Universität Darmstadt
Institut WAR
Petersenstraße 13
64287 Darmstadt
www.iwar.bauing.tu-darmstadt.de
Mr. Prof. Dr.-Ing. F.-B. Frechen
(in place of the Committee of Ex-
perts KA-7 “Membrane bioreactor
process“ of ATV-DVWK or DWA
respectively)
Universität Kassel
FG Siedlungswasserwirtschaft
Kurt-Wolters-Straße 3
34125 Kassel
www.uni-kassel.de
Mr. Dr. Firk
Wasserverband Eifel Rur
Eisenbahnstraße 5
52353 Düren
www.wver.de
Mr. Dr. J. Oles
Mr U. Voss
Oswald Schulze GmbH & Co. KG
Krusenkamp 22 – 24
45964 Gladbeck
www.oswald-schulze.de
AnnexA
272
A.1.3
Scientific assistance for the realization of this publication
Annex A
273
Members of the work group
Membrane Book
Mr. Dr. T. A. Peters
Dr.-Ing. Peters Consulting für
Membrantechnologie und
Umwelttechnik
Broichstraße 91
41462 Neuss
Mr. Dr. V. Mertsch
Ministerium für Umwelt,
Naturschutz, Landwirtschaft und
Verbraucherschutz des Landes
Nordrhein-Westfalen (MUNLV)
40190 Düsseldorf
www.munlv.nrw.de
Ms. K. Drensla
Erftverband
Abteilung Abwassertechnik
(Division waste water engineering)
Forschung und Entwicklung
(Research and development)
Paffendorfer Weg 42
50126 Bergheim
www.erftverband.de
Ms. A. Kaste
Ms. C. Wiedenhöft
Ms. Dr. K. Dreher
Landesumweltamt
Nordrhein-Westfalen (LUA)
Wallneyer Straße 6
45133 Essen
www.lua.nrw.de
Mr. RBD A. Schmidt
Bezirksregierung Köln
(District Government Cologne)
Zeughausstraße 2 – 10
50667 Köln
www.bezreg-koeln.nrw.de
Prof. Dr. rer. nat. W. Schmidt
Fachbereich Versorgungs- und Ent-
sorgungstechnik (Department of
Water Supply, Waste and Waste
Water Disposal Engineering)
Fachhochschule Gelsenkirchen
(Gelsenkirchen University of
Applied Sciences)
45877 Gelsenkirchen
www.fh-gelsenkirchen.de/
fb03/ent/enthf.html
Ms. Dr. J. R. Tschesche
Ms. I. Dierschke
Effizienz-Agentur NRW (EFA NRW)
Mülheimer Straße 100
47057 Duisburg
www.efanrw.de
Mr. T. Wozniak
Aggerverband
Sonnenstraße 40
51645 Gummersbach
www.aggerverband.de
Mr. S. Tenkamp
Staatliches Umweltamt Krefeld
(StUA Krefeld)
(State Environmental Office)
St. Töniser Straße 60
47803 Krefeld
www.stua-kr.nrw.de
AnnexA
274
A.1.4
Other institutions and persons having contributed to the contents
BMU
(Federal Ministry of the Environ-
ment, Nature Conservation and
Nuclear Safety)
DBU
(German Federal Foundation
Environment)
DECHEMA e. V.
(Society for Chemical
Engineering and Biotechnology)
FIGAWA
(Federal Association of
Companies in the Field of Gas
and Water)
PIA e. V.
(Testing and Development
Institute for Waste Water
Engineering at the RWTH
Aachen University)
Ms. E. Brands
Prof. Dr. rer. nat. J. Marzinkowski
Prof. Dr.-Ing. habil. N. Räbiger
Tuttahs & Meyer
Universität Wuppertal
Bergische Universität,
Gesamthochschule Wuppertal
(comprehensive university)
Fachbereich 14, Sicherheitstechnik
(Department of safety engineering)
Gaußstraße 20
42097 Wuppertal
Prof. Dr. rer. nat. J. Marzinkowski
www.uni-wuppertal.de/FB14
Universität Bremen
Institut für Umweltverfahrens-
technik (Institute for Environ-
mental Process Engineering)
Postfach 330440
28334 Bremen
www.fb4.uni-bremen.de
Tuttahs & Meyer Ingenieur-
gesellschaft mbH
Bismarckstraße 2 – 8
52066 Aachen
www.tuttahs-meyer.de
Fachgebiet Sicherheitstechnik/
Umweltschutz der Bergischen
Universität Wuppertal (Department
of Safety Engineering/Pollution
Control)
Campus Freudenberg, Gebäude FF
Rainer-Gruenter-Straße 21
42097 Wuppertal
Frau D. Kunz
www.uws.uni-wuppertal.de
Bundesministerium für Umwelt,
Naturschutz und Reaktorsicherheit
Alexanderplatz 6
10178 Berlin
www.bmu.de
Deutsche Bundesstiftung Umwelt
Postfach 1705
49007 Osnabrück
www.dbu.de
Gesellschaft für Chemische
Technik und Biotechnologie e. V.
Theodor-Heuss-Allee 25
60486 Frankfurt am Main
Mr. Dr. L. Nick
www.dechema.de
FIGAWA Bundesvereinigung
der Firmen im Gas- und
Wasserfach e. V.
Marienburger Straße 15
50968 Köln
www.figawa.de
Prüf- und Entwicklungsinstitut
für Abwassertechnik an der
RWTH Aachen (PIA) e. V.
Mies-van-der-Rohe Straße 1
52074 Aachen
www.pia.rwth-aachen.de
Wasserverband Eifel Rur
Eisenbahnstraße 5
52352 Düren
www.wver.de
Annex A
275
A.1.5
Other information sources in the field of membrane technology
• DWA-Branchenführer Wasserwirtschaft Abwasser-Abfall 2005
(Trade directory water economy waste water – solid waste)
Edited by
Gesellschaft zur Förderung der Abwassertechnik e. V.
Theodor-Heuss-Allee 17
53773 Hennef
www.gfa-ka.de
• ENVITEC- Internationale Fachmesse
für Ver- und Entsorgung mit Fachkongress (International special fair for
water supply, waste water and solid waste disposal with specialist
conference)
www.envitec.de
• IFAT
Internationale Fachmesse für Wasser – Abwasser – Abfall – Recycling
(International special fair for water – waste water – waste recycling)
www.ifat.de
Conferences on membrane technology:
• AMK – Aachener Membran Kolloquium
(Institut für Verfahrenstechnik (IVT) an der RWTH Aachen)
(Aachen Membrane Colloquium, organized by the Institute for Process
Engineering of the RWTH Aachen University)
• ATSV – Aachener Tagung Siedlungswasserwirtschaft und Verfahrens-
technik (Institut für Verfahrenstechnik (IVT) und Institut für Siedlungs-
wasserwirtschaft (ISA) an der RWTH Aachen)
(Aachen Conference on Environmental Engineering and Process Engi-
neering, organized by the Institute for Process Engineering and Institute
of Environmental Engineering of RWTH Aachen University)
• Bremer Colloquium „Produktionsintegrierte Wasser-/Abwassertechnik“
(IUV – Institut für Umweltverfahrenstechnik, Universität Bremen und
GVC – VDI-Gesellschaft Verfahrenstechnik, Düsseldorf)
(Bremen Colloquium “Production-integrated Water and Waste Water
Technology”, organized by the Institute for Environmental Process
Engineering of the Bremen University and GVC-VDI Society Process
Engineering, Düsseldorf)
Information on the Internet
The Internet portal www.pius-info.de is a cooperation project of the
federal states North-Rhine Westphalia, Rhineland-Palatinate and
Schleswig-Holstein. It offers, among other things, information on the
projects realized, literature, software and possibilities for promotion. It is
continuously updated, extended and supported with contents from other
partners.
In January 2002 it received the Umwelt-Online-Award (Environment-On-
line Award) in silver, the seal of quality for modern environmental com-
munication.
Office of the PIUS-Internet-Portal:
c/o Die Effizienz-Agentur NRW
Mülheimer Straße 100
47057 Duisburg
Mr. H. H. Sittel, Ms. A. Schmitt
www.pius-info.de
AnnexA
A.2
Possibilities for promotion
Planning and implementation of measures contributing
to pollution control, such as the utilization of a membrane
system for waste water treatment, may be promoted and
funded in different ways. Comprehensive development
programs of the federal states, the Federal Government
and the EU promote consultancy and give financial sup-
port for innovations and investments, e. g. in the form of
cost sharing, loans, grants. In order to find the adequate
development program and to make the decision easier,
some development programs in the field of “waste water
avoidance, closed process water circuit” are compiled in
the following. The institutions and contact persons men-
tioned give additional information and advice (for the
most part free of charge) concerning the choice of an
adequate development program for each individual case.
276
Development programs of the Federal Government
KfW-Umweltprogramm (environmental program)
ERP – Umwelt- und Energiesparprogramm
(environmental and energy-savings program)
DtA – Umweltprogramm (environmental program)
BMU – Programm zur Förderung von Demonstrationsvorhaben
(program for the promotion of demonstration projects)
Different fields of promotion of DBU
(German Federal Foundation Environment)
Contact
Kreditanstalt für Wiederaufbau
Palmengartenstraße 5 – 9
60325 Frankfurt am Main
Information centre:
0 18 01/33 55 77 (at local rates)
www.kfw.de
Deutsche Ausgleichsbank
Ludwig-Erhard-Platz 1 – 3
53179 Bonn
Information line:
0 18 01/24 24 00 (at local rates)
www.dta.de
DBU – Deutsche Bundesstiftung Umwelt
Postfach 1705
49007 Osnabrück
An der Bornau 2
49090 Osnabrück
Tel.: 05 41/96 33-0
Fax: 05 41/96 33-190
A.2.1
Development programs and advisory service of the Federal Government
Annex A
The use of the promotion data base is only the first step.
The various advisory services of the Chambers of Industry
and Commerce, associations, of management consultancy,
tax advisers and banks help to clarify all questions con-
cerning concepts, taxes or legislation.
A.2.2
Development programs of the federal states
The institutions to be contacted for the development
programs of the federal states are the environmental
ministries or environmental offices of the respective
federal state. Their addresses are compiled in Table A-1.
In addition, a selection of well-known development pro-
grams concerning the subject “waste water avoidance,
closed process water circuit“ is listed together with the
institutions and persons to be contacted.
For the state North-Rhine Westphalia, the Effizienz-
Agentur NRW (EFA) (Efficiency Agency) must be men-
tioned in particular. It is an action group of the Ministry
for Environment and Nature Conservation, Agriculture
and Consumer Protection. Since the end of 1998, it has
been the first institution to contact for all questions con-
cerning production-integrated environmental protection
(PIUS).
The EFA gives advice and supports small and medium-
sized businesses with the introduction of integrated pol-
lution control measures. It establishes contacts to experts
and shows new ways and possibilities for future-oriented
economic structures. The first analysis of the production
by engineers of EFA shows potentials; the following con-
sultation in cooperation with external experts helps the
enterprises to use them (PIUS ®-Check) . The aim is reduc-
ing both the production costs and environmental pollu-
tion by increasing the efficiency of the raw material used.
277
Advisory service of the Federal Ministry of
Economics and Labour (BMWA)
In the information office, founders of businesses and small
and medium-sized businesses seeking advice get quickly
and unbureaucratically information on the development
programs of the Federal Government, the federal states
and the EU, including information on the procedures to be
followed for receiving development funds, on contact in-
stitutions and conditions of the development programs.
Founders of businesses and investors may also fix a date
for a personal conversation in order to get free-of-charge
information about promotion possibilities.
Promotion data base of the Federal Ministry of
Economics and Labour
The promotion data base of the Federal Ministry of Eco-
nomics and Labour is available as central information
source to private individuals, founders of businesses, enter-
prises and consultants. It addresses users without previ-
ous knowledge as well as experts in economic promotion
and allows the search for development funds and ade-
quate promotion programs.
The promotion data base of the Federal Government pro-
vides a complete and topical overview of the development
programs of the Federal Government, the federal states
and the European Union. The promotion activities are
summarized according to uniform criteria, independent
of the promotion level or the funding institution, and
represented consistently. The connections between the
individual programs are also explained, this is important
for the efficient use of government promotion.
The comprehensive cross-linkage on the Internet allows
to get more detailed information on the different pro-
viders of promotion information.
Advisory service of BMWA
Tel.: +49 (0)30/20 14-800
Fax: +49 (0)30/20 14-70 33
E-Mail: [email protected]
Promotion data base of the
Federal Ministry of Economics and Labour
www.bmwa.bund.de
1) PIUS® is a registered trademark of the Effizienz-Agentur NRW
AnnexA
In addition, the EFA informs about topical possibilities for
the promotion of small and medium-sized businesses and
helps in searching the adequate development program for
financing of projects in the field of production-integrated
environmental protection. The headquarters of the EFA is
the House of Economic Promotion in Duisburg. Since the
beginning of the year, four regional offices at Aachen, Biele-
feld, Münster and Siegen have ensured direct contact in
the different economic regions of North-Rhine Westphalia.
In addition, the publication “Förderprogramme für den
Produktionsintegrierten Umweltschutz“ (Development
programs for production-integrated environmental pro-
tection) gives an overview of the different promotion
278
EFA – Die Effizienz-Agentur NRW: “Förderprogramme für den Produk-
tionsintegrierten Umweltschutz“. Zielgerichtet planen. Effizient
umsetzen. Umfassend profitieren. (“Development programs for pro-
duction-integrated environmental protection”. Calculated planning.
Efficient implementation. Comprehensive profit.) As of 06/2000.
Baden-Württemberg
Bavaria
Berlin
Landesanstalt für Umweltschutz (LfU)
Baden-Württemberg
Griesbachstraße 1
76185 Karlsruhe
Postfach 21 07 52
76157 Karlsruhe
Tel.: +49 (0)7 21/9 83-0
Fax: +49 (0)7 21/9 83-14 56
www.lfu.baden-wuerttemberg.de
Bayerisches Staatsministerium für
Landesentwicklung und Umweltfragen
Rosenkavalierplatz 2
81925 München
Tel.: +49 (0)89 / 92 14-00
Fax: +49 (0)89 / 92 14-22 66
www.umweltministerium.bayern.de
Senatsverwaltung für Stadtentwicklung
Brückenstraße 6
10179 Berlin
Tel.: +49 (0)30/90 25-0
Fax: +49 (0)30/90 25-29 20
www.stadtentwicklung.berlin.de/umwelt
Development program for pollution control and
energy saving measures
Contact:
L-Bank; Wirtschaftsförderung II
Friedrichstraße 24
70174 Stuttgart
Telephone hotline: +49 (0)7 11/1 22-23 45
Fax call for information on the conditions:
+49 (0)7 11/1 22-26 74
www.l-bank.de
Additional program of LfA-Umweltschutz
Contact:
LfA Förderbank Bayern
Königinstraße 17
80539 München
Tel.: +49 (0)1 8 01/21 24 24 (at local rates)
www.lfa.de
Das Umweltentlastungsprogramm – UEP
(program for pollution reduction)
Contact: Beratungs- und Servicegesellschaft
Umwelt mbH (B & SU)
Hohenzollerndamm 44
10713 Berlin
Tel: +49 (0)30/3 90 42-84
www.uep-berlin.de
Table A-1
Contacts for development programs of the federal states and selected development programs concerning
“waste water avoidance, closed process water circuits“
Federal state Contact Development programs
possibilities. Besides much additional information on
production-integrated environmental protection, the
Internet portal www.pius-info.de offers information on
promotion possibilities. The Internet portal is a joint pro-
ject of the federal states North-Rhine Westphalia, Rhine-
land-Palatinate and Schleswig-Holstein, it is continuously
updated and extended.
Annex A
279
Brandenburg
Bremen
Hamburg
Hesse
Mecklenburg-Vorpommern
Ministerium für Landwirtschaft, Umweltschutz
und Raumordnung des Landes Brandenburg
Heinrich-Mann-Allee 103
14473 Potsdam
Tel.: +49 (0)3 31/8 66-0
Fax: +49 (0)3 31/8 66-70 68, -70 69, -70 71
www.brandenburg.de/land/mlur
Der Senator für Bau und Umwelt
Hanseatenhof 5
28195 Bremen
Tel.: +49 (0)4 21/3 61-21 36
Fax: +49 (0)4 21/3 61-60 13
www.umwelt.bremen.de
Freie und Hansestadt Hamburg
Behörde für Umwelt und Gesundheit
Fachamt für Energie und Immissionsschutz (I1)
Billstaße 84
20539 Hamburg
Tel.: +49 (0)40/4 28 45-0
www.hamburg.de/Behoerden/Umweltbehoerde
Hessisches Ministerium für Umwelt,
Landwirtschaft und Forsten
Bereich Umwelt und Energie
Mainzer Straße 80
65189 Wiesbaden
Tel.: +49 (0)6 11/8 15-0
Fax: +49 (0)6 11/8 15-19 41
www.mulf.hessen.de
Umweltministerium Mecklenburg-Vorpommern
Allgemeine Information und Koordinierung
der Förderprogramme
Schlossstraße 6 – 8
19053 Schwerin
Tel.: +49 (0)3 85/5 88-0, -8 20
Fax: +49 (0)3 85/5 88-87 17
www.um.mv-regierung.de
Development program for environmental technology
Contact:
see left
Freie und Hansestadt Hamburg
Behörde für Umwelt und Gesundheit
Innovation Foundation Hamburg
Alter Steinweg 4
20459 Hamburg
Tel.: +49 (0)40/4 28 41-17 59
www.hamburg.de/Behoerden/Umweltbehoerde
Table A-1 (Continuation)
Contacts for development programs of the federal states and selected development programs concerning
“waste water avoidance, closed process water circuits“
Federal state Contact Development programs
AnnexA
280
Lower Saxony
North-Rhine Westphalia
Rhineland-Palatinate
Niedersächsisches Umweltministerium
Postfach 4107
30041 Hannover
Tel.: +49 (0)5 11/1 20-0
Fax: +49 (0)5 11/1 20-33 99
www.mu.niedersachsen.de
Ministerium für Umwelt und Naturschutz,
Landwirtschaft und Verbraucherschutz des
Landes Nordrhein-Westfalen
Schwannstraße 3
40 476 Düsseldorf
Tel.: +49 (0)2 11/45 66-0
Fax: +49 (0)2 11/45 66-3 88
www.munlv.nrw.de
Landesumweltamt NRW
Wallneyer Straße 6
45133 Essen
Tel.: +49 (0)2 01/79 95-0
Fax: +49 (0)2 01/79 95-14 48
www.lua.nrw.de
Effizienz-Agentur NRW
Mülheimer Straße 100
47057 Duisburg
Tel.: +49 (0)2 03/3 78 79-58
Fax: +49 (0)2 03/3 78 79-44
www.efanrw.de
Ministerium für Umwelt und Forsten
Kaiser-Friedrich-Straße 1
55116 Mainz
Tel.: +49 (0)61 31/16-0
Fax: +49 (0)61 31/16 46 46
www.muf.rlp.de
“Action group Ecological and Sustainable Water
Management in North-Rhine Westphalia NRW“
Development area 1: Innovative or proved
production-integrated environmental protection
Contact:
see left, and in addition:
INVESTITIONS-BANK NRW
Zentralbereich der WestLB
Friedrichstraße 56
40217 Düsseldorf
Tel.: +49 (0)2 11/8 26-09
Fax: +49 (0)2 11/8 26-84 59
IISB loans for small and medium-sized businesses
within the scope of pollution control
Contact:
Investitions- und Strukturbank Rheinland-Pfalz
(ISB) GmbH
Holzhofstraße 4
55116 Mainz
Tel.: +49 (0)61 31/9 85-3 50
www.isb.rlp.de
Table A-1 (Continuation)
Contacts for development programs of the federal states and selected development programs concerning
“waste water avoidance, closed process water circuits“
Federal state Contact Development programs
Annex A
281
Saarland
Saxony
Saxony-Anhalt
Schleswig-Holstein
Thuringia
Ministerium für Umwelt
Keplerstraße 18
66117 Saarbrücken
Tel.: 06 81/5 01-00
Fax: 06 81/5 01-45 21
www.umwelt.saarland.de
Sächsisches Staatsministerium für Umwelt und
Landwirtschaft
Archivstraße 1
01097 Dresden
Tel.: 03 51/5 64-0
Fax: 03 51/5 64-22 09
www.smul.sachsen.de
Ministerium für Landwirtschaft
und Umwelt des Landes Sachsen-Anhalt
Olvenstedter Straße 4
39108 Magdeburg
Tel.: 03 91/5 67-01
Fax: 03 91/5 67-17 27
www.mrlu.sachsen-anhalt.de
Landesamt für Natur und Umwelt des Landes
Schleswig-Holstein (LANU)
Hamburger Chaussee 25
24220 Flintbek
Tel.: 0 43 47/7 04-0
Tel.: 0 43 47/7 04-12
www.umwelt.schleswig-holstein.de
Thüringer Ministerium für Landwirtschaft,
Naturschutz und Umwelt
Beethovenplatz 3
99096 Erfurt
Tel.: 03 61/37-9 00
Fax: 03 61/37-9 99 50
www.thueringen.de/de/tmlnu
Compilation of topical development programs in
the field of energy and pollution control
Contact:
Investitionsbank Schleswig-Holstein
Fleethörn 29-31
24103 Kiel
Tel.: 0431 / 900 3651
www.lanu.landsh.de
Table A-1 (Continuation)
Contacts for development programs of the federal states and selected development programs concerning
“waste water avoidance, closed process water circuits“
Federal state Contact Development programs
AnnexA
A.2.3
Development programs of the EU in the field of
pollution control and water management
Structural and regional promotion
Structural and regional promotion by the European
Union is based on the four European Structural Funds:
European Regional Development Funds (ERDF), European
Social Funds (ESF), The European Agricultural Guidance
and Guarantee Fund (EAGGF) and the Financial Instru-
ment for Fisheries Guidance (FIFG). Concerning measures
in the field of pollution control, the ERDF is the most
important Structural Funds of the EU.
• Structural Funds
The aim of European Regional Development Funds
(ERDF) is to promote economic and social cohesion by
correcting the main regional imbalances and partici-
pating in the development and conversion of the various
regions. The ERDF funds are provided for certain less-
favoured regions and mainly used to finance improvement
of the infrastructure, productive investments, local
development and protection of the environment.
For promotion, it is distinguished between Objective 1
and Objective 2 regions.
Objective 1 supports the development and structural
adaptation of underdeveloped regions. Among them are
those regions with a per capita gross domestic product
(GDP) lower than 75% of the Community average.
Five main actions are provided:
• Promotion of the competitiveness of the industry and
small and medium-sized businesses
• Development of the infrastructure
• Protection of the environment
• Development of the manpower potential
• Development of rural areas
Objective 2 supports the economic and social conversion
of areas experiencing structural difficulties. During the
period 2000-2006, it is distinguished between four types
of areas with structural difficulties:
• Industrial areas
• Rural areas
• Urban areas
• Areas depending on fishery
The measures within the scope of the Objectives 1 and 2
are co-financed. The maximal part of the EU for Germany
and Objective 1 is 75 %, for Objective 2 maximally 50.
Development programs in the field of environmental
protection
The main objectives of the development programs descri-
bed in the following are the protection of the environment
and the development of the environmental policy of the
Community.
LIFE III Program
The general objective of LIFE is to contribute to the im-
plementation, updating and development of Community
policy and legislation relating to the environment, in
particular, with regard to the integration of the environ-
ment into other policies, as well as to sustainable devel-
opment in the Community.
LIFE offers financial support for environmental measures
in the Community and certain third countries (Mediter-
ranean countries or littoral states of the Baltic Sea,
countries of Central and East Europe which have signed
association agreements with the European Union).
The following areas are promoted by LIFE:
• European Community, Central and East European
countries: nature conservation, promotion of
sustainable development in industrial activities, inte-
gration of environmental aspects in regional planning
policy, waste management, atmospheric pollution and
water management;
• other Third Countries: technical assistance in the
establishment of administrative structures, maintenance
and rehabilitation of habitats of endangered species,
promotion of sustainable development.
282
Annex A
The eligibility for promotion mainly depends on the
following points:
• The measures in the European Community have to be
of Community interest, they must be innovative,
reliable and feasible.
• The measures outside the Community must be techni-
cally and financially feasible and contribute to sustain-
able development and cooperation.
Die Aktion wird in den betreffenden fünf Jahren (2000 –
2004) auf drei wichtige Bereiche konzentriert:
Over the respective five years (2000 – 2004), the action
will focus on three important fields:
• Nature conservation (LIFE-Nature): actions aimed at
conservation of natural habitats and the wild fauna
and flora of European Union interest They support
implementation of the nature conservation policy and
the Natura 2000 Network of the European Union.
• Environment (LIFE-Environment): actions which aim
to implement the Community policy and legislation
on the environment in the European Union and candi-
date countries. This approach enables demonstration
and development of new methods for the protection
and the enhancement of the environment.
• Third countries (LIFE-Third Countries): actions con-
cerning technical assistance activities for establishing
administrative structures in the field of environmental
protection, actions for nature conservation and
demonstration measures for promoting sustainable
development in some Mediterranean countries and
littoral states of the Baltic Sea.
For actions financed by the LIFE program, a subsidy of
50 % of the total costs is given. Within the scope of LIFE-
Environment, demonstration projects are funded which,
however, must not be research, studies or investments in
infrastructure. The proposals must have for subject pilot
actions or actions concerning technical assistance which
are suited to improve the environmental conditions in a
quantifiable way and which can be reproducible at other
locations of the European Union.
In Germany, eight projects are being promoted by LIFE-
Environment in 2004, one of it in the field of waste
water with the subject “Nutrient removal by membrane
bioreactors“. This project called ENREM will run until
December 2006. It is realized by Kompetenzzentrum
Wasser Berlin GmbH.
EU contact:
General Direction Environment
LIFE-Program
Bruno Julien
General Direction Environment D. 1
BU 2/01
Rue de la Loi 200
B-1049 Brüssel
Instrument for structural policies for pre-accession
(ISPA)
This development program aims at preparing the countries
Estonia, Latvia, Lithuania, Poland, The Czech Republic,
Slovakia, Hungary, Slovenia, Romania, Bulgaria) for acces-
sion. Investment projects in the field of national trans-
port and environment are funded.
Community assistance under the ISPA is granted for the
period 2000-06. The total budget is 7 billion s . The rate
of assistance may be up to 75 % of the total costs in the
form of non-repayable subsidies for public administra-
tions and public enterprises.
Further information:
http://www.europa.eu.int/comm/regional_policy/
index_en.htm
EU contact:
General Direction Regional Policy
Rue de la Loi
B-1049 Bruxelles
E-Mail: [email protected]
283
AnnexA
284
Definition of the objective
Expansion/Upgrade of activated sludge stages
New construction
Upgrade in order to comply with more stringent demands
...
A.3
Short check lists for Figure 2-1
1 Reason and objective
Technical boundary conditions
Demands on the effluent (minimum requirements/more far-reaching requirements)
Capacity of an existing waste water treatment plant
Drainage system
Inflow features
Conversion/possible addition of membranes into existing tanks
...
Economic conditions
Investments, in particular specific membrane costs
Subsidies for investments
Operating costs (membrane replacement costs, cleaning, energy consumption)
Waste water charge
...
2 Analysis of the current situation
Utilization of existing tanks
New construction of tanks and membrane stage
Selection and arrangement of the membrane modules
Necessary pretreatment measures
Design and realization of membrane cleaning
3 Study of variations
Design
Sludge age, sludge loading, excess sludge production
Solid matter content in the activated sludge tank
Minimum retention time, mixing and compensating tank
Distribution of denitrification, nitrification and variable zone
Oxygen carry-over by recirculation
Necessary membrane surface area for constantly stable flow rates
Influence of the temperature on the permeability
Membrane surface area available in the case of cleanings
Module ventilation according to the manufacturer’s specification
Oxygen input depending on the solid matter content
Phosphorus removal
Sludge treatment: dewatering and digestibility
…
4 Planning, design and construction
Design of the construction
Pretreatment quality (screen, separator for light-density material)
Buffer tank in the inflow or the installation
Realization of two or more lines
Hydraulic decoupling of several lines
Short membrane replacement and delivery times
Devices for membrane cleaning
Power supply
…
4 Design of the construction (continuation)
Operating stability
Training/instruction of the staff
Guarantee of the filtration capacity
Control of the membrane state (sticking of fibrous material etc.) and permeability
Regular membrane cleaning (intermediate, intensive cleanings)
Operating costs
Energy consumption of tank and module aeration
Service life of the membranes
Costs of cleaning agents
Regular membrane cleaning (intermediate, intensive cleanings)
…
Safety at work
Handling of cleaning agents
…
5 Operation and control
Annex A
285
AnnexA
286
Compliance with the demands
Cost reduction
Saving of water
Saving of chemicals
Saving of energy
Recovery of valuable substances
Reduction of discharge costs
Reduction of the transport costs
Reduction of waste water charges
…
A.4
Short check lists for Figure 3-1
1 Reason and objective
Data recording
Production process
Input and output of resource flows
Determination of the material flows and place of their production
Waste water flows
Waste water volume, chemical and physical quality
Valuable and undesired substances in the flow to be treated
Processes limiting the process, and other restrictions
Costs for the current situation, i. e. without recovery and recycling under monetary and environmental-engineering aspects
…
Suggestions for improvements / potentials
Possibilities for avoidance in the production process
Treatment of residual matter
Is it possible to recover valuable resources from the material flow?
Utilization / whereabouts of the valuable material recovered
…
2 Analysis of the current situation
Definition of the objective
Possible separation processes
Is it necessary or possible to modify the production process?
Effectiveness of the processes?
Is it possible to attain the required objectives by this process?
Comparison of the economic efficiency
Laboratory tests, pilot tests
3 Selection of the process
Annex A
287
Comparison of the economic efficiency
Existing process, no change
Costs of water supply
Energy costs
Costs of chemicals
Costs of raw material
Discharge costs for liquid waste
Disposal costs for solid waste
Laboratory costs
…
Membrane process installed
Investments for new installation
Membrane replacement costs
Investments for peripheral installations, pumps, equalization tank …
Separated valuable material
Possibilities for promotion
…
3 Selection of the process (Continuation)
Tests on different levels
Preliminary tests
Laboratory tests
Choice of membranes
Pilot tests
Planning of the installation
…
Operator model or owner-operated
e. g. ”BOO Build-Own-Operate“
…
Contract regulation
Duration of the contract
Guarantee period, service life of the membranes
Price regulation
…
5 Operation and control
4 Planning and pilot phase
AnnexA
A.5
Work report of the ATV-DVWK working group
IG-5.5 “Membrane Technology”: Treatment of indus-
trial waste water and process water by membrane
processes and membrane bioreactor processes
This work report has been established by the ATV-DVWK
working group IG-5.5 “Membrane Technology” of the
ATV-DVWK Committee of Experts IG-5 “Industrial Waste
Water Treatment”. The report consists of several parts.
Part 1 deals with the membrane treatment process itself,
i. e. with its use for the separation of undissolved, colloidal
or dissolved substances.
Part 2 looks into the membrane bioreactor process. It
focuses on the process unit consisting of biological de-
gradation in the aeration tank and separation of the bio-
mass by membranes. It deals in particular with the requi-
rements and specific features of the membrane bioreactor
process compared to the conventional activated sludge
process. A third part is planned in which concrete exam-
ples, operating experience and design instructions will be
summarized.
The ATV-DVWK working group included the following
members:
Dr.-Ing. Goetz Baumgarten, Langenhagen
Dr.-Ing. Martin Brockmann, Hilden
Dipl.-Biol. Ulrich Brüß, Herten
Prof. Dr.-Ing. Peter Cornel, Darmstadt (speaker)
Dr.-Ing. Oliver Debus, Hamburg
Dipl.-Ing. Michael Kiefer, Stuttgart
Dr.-Ing. Angelika Kraft, Essen
Prof. Dr. Peter M. Kunz, Mannheim
Dr.-Ing. Otto Neuhaus, Bergkamen
Dr.-Ing. Thomas Peters, Neuss
Prof. Dr.-Ing. Karl-Heinz Rosenwinkel, Hannover
(deputy speaker)
Prof. Dr.-Ing. em. Carl Seyfried, Hannover (chairman)
Dr.-Ing. Jianming Shang, Hamm
Prof. Dr.-Ing. Ulf Theilen, Gießen
Dr.-Ing. Frieder Wagner, Heuweiler
With the cooperation of:
Dipl.-Biol. Annette Achtabowski, Bergkamen
Dipl.-Ing. Stefan Krause, Darmstadt
Prof. Dr. Winfried Schmidt, Gelsenkirchen
Dipl.-Ing. Jens Wagner, Hannover
Part I
Membrane processes
A.5.1
Introduction
Membrane processes are pure physical processes for
material separation, by which the waste water or the pro-
cess water to be treated is separated into purified water
(filtrate or permeate) and a concentrated phase (concen-
trate) (Figure A-1). The driving force for these separation
processes is the transmembrane pressure difference. These
pressure-driven processes differ in the extent of the pres-
sure difference. Membrane processes based on other
driving forces, such as an electrical field or a concentra-
tion difference, will not be discussed here because of
their insignificant practical importance in waste water
treatment. In contrast to conventional filtration techno-
logies, pressure-driven membrane processes allow for
separation up to the molecular range.
Two features are of special importance for the success of
a membrane process:
• the selectivity of the membranes, i. e. their capacity to
distinguish between the components of a mixture (e. g.
between oil and water or between ions and water). The
membrane hinders the transport of various components
in different ways.
• the performance of the membrane (often called mem-
brane flux), i. e. the permeate or filtrate (usually given
in L/(m2 �h) to be obtained under certain operating
conditions.
288
Annex A
Figure A-2 shows the classification of the membrane pro-
cesses as function of the particle or molecular size and
the pressure difference.
With membrane processes it is possible to separate waste
water constituents, such as:
• solids
• dissolved matter
• colloids and
• liquids of a second phase
289
waste water(feed)100 %
membrane process treated waste water(permeate/filtrate)e. g. 90 %
concentrated waste wateror reusable matter(concentrate)e. g. 10 %
Figure A-1
Schematic representation of the basic principle of a membrane process
1
0,1
0,0001
particle or molecular size [µm]
pre
ssur
e d
iffe
ren
ce [
bar
]
0,001 0,01 0,1 1 10 100
10
100
200
reverse osmosis
nanofiltration
ultrafiltration
microfiltration
filtration
common salts
metal salts
virus bacteria
coloured pigments
Figure A-2
Classification of membrane and filtration processes
AnnexA
Independent of the process or the separation goal, various
treatment objectives can be pursued which are of economic
interest, for example:
1.water purification e. g. for
• compliance with the discharge standards
• reuse
2.concentration of water constituents, e. g. for
• recovery of reusable material
• reduction of discharge costs
To understand the selectivity of membranes, models have
been developed which can be condensed, for a coarse
overview, into two borderline cases. One distinguishes
the so-called solution-diffusion membranes (reverse
osmosis, nanofiltration) and the pore membranes (micro-
and ultrafiltration).
• The solution-diffusion membranes have a homogeneous
interlayer, comparable to a gel. To pass the membrane,
the substance must dilute in the membrane material.
Consequently, the selectivity is based on the varying
solubility and the varying passage velocity of the sub-
stances to be separated through the membrane material.
Material transport through the membrane takes place
according to the principles of diffusion (Fick principle).
The driving force for the dissolved substances in all
diffusion-controlled membrane processes is the dif-
ference in the chemical or electrochemical potential
at both sides of the membrane, while the driving force
for the solvent, i. e. the water, is the pressure difference.
This model describes the separation effect of reverse
osmosis membranes. To describe the separation features
of nanofiltration membranes, electrochemical inter
actions with the membrane surface, which as a rule is
negatively charged, must also be considered.
• The pore membranes have a porous structure with
channels. The selectivity is based on a screening effect
which is determined by the pore size distribution of
the membranes. Material transport takes place in a
pure convective way according to the principles of the
laminar capillary tube flow (Hagen-Poisseulle principle)
as a result of the pressure difference between both sides
of the membrane. This model describes theoretically
the separation effect of micro- and ultrafiltration mem
branes. In practice, however, these processes are as a
rule controlled by a covering layer. This covering layer
(“secondary membrane”) develops from the substances
concentrated on the membrane surface.
Due to the concentration of the water constituents taking
place at the raw-water side of the membrane, the follo-
wing effects may occur on the membrane surface as well
as on components of the membrane elements or the
membrane modules which have negative effects on the
performance of a membrane installation:
scaling
deposition of inorganic water constituents after precipi-
tation by supersaturation, crystal formation
fouling
formation of a covering layer by organic water constituents
biofouling
formation of a biofilm by microorganisms
These effects can be avoided or at least minimized by cor-
responding measures. It is for example possible to avoid
the precipitation of inorganic components such as CaSO4
or CaCO3 by shifting the pH value (and, with this, the
solubility limit) and/or dosing of anti-scaling agents
(complexing agents, e. g. phosphonic acid, polycarboxylic
acid). The formation of a biofilm can be avoided or mini-
mized by corresponding pretreatment of the raw water
as well as backwashing and cleaning of the membranes
adapted to the special case.
290
Annex A
291
A.5.2
Choice of a membrane process
When choosing a membrane process, at first four impor-
tant decisions have to be made:
• determination of the necessary molecular separation
size of the membrane to be chosen
• determination of the membrane material
• decision on the module type
• decision of the process
The criteria for this choice are described in the following.
A.5.2.1
Determination of the necessary molecular
separation size
The type of the components to be separated from a waste
water or a process water, i. e. the necessary selectivity,
determines the type of the membrane to be used. Some
examples in Table A-2 illustrate the classification of the
separation of water constituents with the membrane
types. For the pore membranes, the pore size, utilized by
majority in practice, is indicated. The units and separa-
tion sizes used in the Table correspond to the terms ap-
plied normally by the membrane manufacturers. The
unit (g/mol) for the molecular weight corresponds to the
unit Dalton which is used in other publications.
A.5.2.2
Determination of the membrane material
Today nearly the whole membrane technology in the field
of water and waste water treatment is based on synthetic
polymer membranes, briefly described in the following.
In spite of high investment costs, ceramic membranes
recently have become established in special fields of ap-
plication (high temperatures, aggressive media, solvents).
From the general material transport principles (convection,
diffusion) it is known that the permeate flow [L/(m2 � h)]
is inversely proportional to the length of the transport way.
For this reason, the membrane manufacturers have tried
to make available rather thin separating layers. Yet the
mechanical strength of the membrane has to be ensured.
While in microfiltration, as a rule, symmetric membranes
are used, asymmetric membranes have gained acceptance
in ultra- and nanofiltration as well as in reverse osmosis.
In this case, one distinguishes between phase-inversion
and composite membranes, depending on the production
process. Active layer and substructure of the phase inver-
Abtrennbare Trenngrenze Verfahren Betriebsdruck
Wasserinhaltsstoffe (Porengröße) [Membran-Typ] kPa (bar)
Table A-2
Membrane processes and their fields of application
Partikel > 0.1 µm 0.1 – 1 µm Microfiltration (MF) 50 – 300 kPa
emulgierte Stoffe (pore membranes) (0.5 – 3 bar)
Kolloide, Makromoleküle 2,000 – 200,000 g/mol Ultrafiltration (UF) 50 – 1,000 kPa
Molmasse > 2,000 g/mol (0.004 – 0.1 µm) (pore membranes) (0.5 – 10 bar)
emulgierte Stoffe
Organische Moleküle > 200 g/mol Rückhaltung Nanofiltration (NF) 500 – 4,000 kPa
mehrwertige, anorganische Ionen MgSO4 > 90 % (solution-diffusion (5 – 40 bar)
(0.001 – 0.005 µm) membranes with integrated
ionogenic groups)
Organische Moleküle und alle Ionen < 200 g/mol Rückhaltung Reverse osmosis (RO) 500 – 7,000 kPa
für NaCl > 95 % High-pressure reverse osmosis (5 – 70 bar)
(solution-diffusion membranes) up to 12,000 kPa
(up to 120 bar)
AnnexA
sion membrane are made from the same material, while
composite membranes have a thin, homogeneous poly-
meric layer cast on a support back-up structure which
enables separate optimization of the layers. The Figures
A-3 and A-4 show the general structure of phase-inver-
sion and composite membranes.
The membranes produced from cellulose derivates often
applied in the past have been replaced to a great extent
by membranes from completely synthetic polymers (poly-
sulphone, polyether sulphone, polyamide, polypropylene,
polyacrylonitrile etc.). These membranes offer the particular
advantage of being more resistant to the various media.
Table A-3 gives an overview of the most current membrane
materials used for the different membrane processes.
292
Figure A-3
Cross-section of a phase-inversion membrane,
example: UF hollow-fibre membrane
microporous backing materialup to a thickness of 50 µm
porous polyester networkup to a thickness of 125 µm
active layer up to 2500 Å= 1/4000mm thickness barrier layer
2500 Å
Figure A-4
Composite membrane, left: general structure of a composite membrane, right: cross-section of a composite
membrane
Annex A
293
A.5.2.3
Determination of the membrane module
The main element of each membrane installation is the
module in which the membrane surface area is arranged
as an engineered system. The ideal module ensures the
following aspects:
• good and constant flow over the membranes without
dead-water zones
• low pressure losses
• high packing density
• low-cost production
• easy cleaning
• easy replacement of the membranes
• low disposition for clogging
Since no module is capable of meeting all these contra-
dictory requirements in an optimal way, various module
types have been developed, including some designs for
Microfiltration polypropylene (PP)
polyvinylidene fluoride (PVDF)
polysulphone (PSU)
�-aluminium oxide
high-grade steel, titanium dioxide
zirconium oxide
Ultrafiltration polysulphone (PSU)
reg. cellulose
polyacrylonitrile (PAN)
polyether sulphone (PES)
titanium oxide, zirconium oxide
polyvinylidene fluoride (PVDF)
Nanofiltration polyamide (PA)
(zirconium oxide), PES
cellulose acetate (CA)
Reverse osmosis polyamide (95 %)
cellulose acetate (5 %)
Table A-3
Overview of the most current membrane materials for the different membrane processes
Process Active layer
specific applications. Disregarding constructive details,
the modules can be subdivided into two groups:
modules with tubular membranes
• tube module
• capillary module
• hollow-fibre module
modules with flat membranes
• plate module
• spiral-wound module
• cushion module
• rotating module
AnnexA
The size and investment and operating costs of a mem-
brane installation are closely related to the specific per-
meate performance and the membrane surface area to be
installed. It has to be arranged as favourably, i. e. as com-
pact as possible, without endangering the operational
safety.
In waste water engineering, this means that the type and
concentration of the solid matter fed to a membrane
installation and the solid matter formed in the course of
the process decisively influence the module system to be
chosen. Table A-4 gives an overview of the features and
fields of application of the different module types.
The structure of the different modules is represented in
Figures A-5 – A-7.
294
Type (examples) Packing density [m2/m3] Specific costs per m2 Covering layer control Fields of application
Table A-4
Features and fields of application of different module types
Rotating module 10 – 50 – – – + + + MF and UF
Tube module 20 – 90 – – + + MF, UF, NF, RO
Plate and cushion module 100 – 250 – + + MF, UF, NF, RO
Capillary module 600 – 1,200 0 + MF, UF, NF
Spiral-wound module 700 – 1,000 + – RO, NF, UF
Hollow-fibre module > 1,000 ++ – – RO, UF
– negative 0 average + positive
Figure A-5
Front view of a tube module with 5.5 mm tubular
membranes [photo: X-FLOW]
Figure A-6
View of a cushion module (type ROCHEM FM)
permeate collecting tube(central tube)
tube water
permeate outlet afterpassage through themembrane concentrate
membrane
permeate spacer
feed spacer
feed
wrap
permeate
permeatespacer
membrane
Figure A-7
Principle of a spiral-wound module
A.5.2.4
Determination of the operating mode of
membrane installations
Like the choice of the module, the operating mode of a
membrane process is determined by the load or the con-
centration of the dissolved and/or the undissolved
constituents of the respective waste water or process
water. The specific energy demand of the operating mode
influences the economic efficiency and, with this, the
feasibility of the individual applications.
As a rule, membrane processes are operated in cross-flow
mode, also called tangential flow. Tangential flow to the
brine or concentrate side of the membrane attempts to
limit the development of a covering layer on the mem-
brane and to maintain a constant permeate flow at the
highest possible level.
Annex A
295
The dead-end operation stands in contrast to the cross-
flow mode. Like in classical cake-forming, static filtration,
the filtration capacity decreases with increasing thickness
of the covering layer. Combined with an effective back-
washing technique, this operating mode is used success-
fully in microfiltration and ultrafiltration applications.
The combination of both operating modes is called semi-
crossflow mode.
Both operating modes, dead- end and cross-flow, differ
considerably in their energy demand. Pure cross-flow
processes need between 2 kWh/m3 and 10 kWh/m3 (for
MF and UF) or between 0.5 and 5 kWh/m3 (for NF and
RO), while pure dead-end processes operate with an ener-
gy consumption of between 0.1 and 0.3 kWh/m3.
AnnexA
A.5.3
Examples for the use of membrane processes
Pressure-driven membrane processes have proved their
suitability in many fields. The following list does not
claim to be complete.
• filtration of pickling acids (MF, UF)
• treatment of waste water from a CP plant in
electroplating (RO)
• treatment of landfill leachate (NF, RO)
• extension of the service life of degreasing baths
(MF, RO)
• recovery of reusable material from dyeing waste
water (UF)
• treatment of waste water from flexographic
printing (MF)
• treatment of waste water from spark erosion (MF)
• treatment of waste water from slide grinding (MF)
• treatment of grey water on ships (RO)
• water recycling from solid matter-containing waste
water from the production of semiconductor
elements (CMP, grinding, sawing) (UF)
• reutilization in the semiconductor industry (RO)
• oil separation from compressor condensates (MF)
• concentration of cutting oils (UF)
• treatment of lyes (MF, UF, NF)
• reutilization in the food industry (RO)
• treatment of rinsing water from degreasing in the
metal-processing industry (RO)
• treatment of recirculation water in non-metal
processing (UF)
• separation of biologically hardly degradable organic
components (NF)
• treatment of waste water from flue gas cleaning (MF)
• treatment of acids (NF)
• treatment of sludge water (filter backwash water) (UF)
• treatment of sludge water in swimming-pools (RO)
• concentration before thermal treatment (RO)
• pretreatment of waste water for further treatment by
reverse osmosis (MF, UF)
• closing of water cycles (UF, NF, RO)
• recovery of reusable material from water-based paint
(UF)
• reduction of germs in the effluents of waste water
treatment plants (MF, UF), see Part 2 of the work report
• retention of sludge in membrane bioreactors
(MF, UF), see Part 2 of the work report
A.5.4
Planning of membrane installations
A.5.4.1
Acquisition of basic data
As a basis for the planning of a membrane installation,
all relevant data on the waste water or process water to
be treated has to be collected for the longest possible
period and documented in an adequate way. This data con-
cerns volume flow or batch quantity, chemical/physical
parameters and other process-specific dissolved and undis-
solved water constituents (see chapter A.5.6 “Questionnaire
for the acquisition of process data”).
Besides the waste water situation of the present-day oper-
ating state, the water balance of the whole enterprise
also has to be determined in order to get the basis for the
specification of the objective and a rough assessment of
the effects of a new process concept on the operation.
The assessment of the potential for savings and the results
expected should be completed by examinations of partial
flows and of changes concerning upstream process steps.
A.5.4.2
Planning and design
When the acquisition of basic data has shown that a certain
membrane process can be used, the procedure described
below should be followed because it has proved successful
in planning such installations. As a rule, successful opera-
tion can only be ensured by the procedure described.
A.5.4.2.1
Preliminary laboratory tests
The preliminary tests serve for first orientation and are
usually carried out with reference to the following aspects:
• selection of membranes and modules with determina-
tion of the general suitability of a medium to be
treated by the membrane process chosen
296
Annex A
• preselection of potentially necessary pretreatment
measures, assessing at the same time the scaling,
fouling and biofouling potential, and preliminary tests
on membrane cleaning
• approximate determination of the most important
process parameters such as pressure, temperature,
overflow velocity and attainable output
A.5.4.2.2
On-site pilot tests
The pilot tests to be outlined on the basis of the laboratory
tests serve to establish the specific design basis, the purifi-
cation strategies and other process-engineering and installa-
tion-specific conditions. The pilot installation has to be
planned in such a way that the hydraulic conditions (over-
flow conditions of the membrane, module connection)
of the membrane elements, i. e. of the modules, can be
transferred to the large-scale installation. Only in this way
will up-scaling be possible without problems. The pilot tests
should be carried out with the following considerations:
• on-site operation of a semi-technical pilot plant in con-
tinuous operation under practical conditions, taking
down all data relevant for calculation including pre-
treatment
• determination of the permeate efficiency as function of
the process section and the time
• of the membranes: determination of the cleaning
intervals, optimization of the cleaning processes, deter-
mination of the demand for chemicals
Optimal chemical cleaning of the membranes is impor-
tant for their continuous functioning. Depending on the
type of contamination, different chemicals have to be
used. A cleaning strategy has to be developed for each
single case, but in principle the following chemicals are
used for the different types of contamination:
membrane contamination by scaling: cleaning by
acids, e. g. citric acid, hydrochloric acid; if necessary,
complexing agents
membrane contamination by fouling: cleaning by
oxidizing agents, e. g. hydrogen peroxide, peracetic acid,
sodium hypochlorite
membrane contamination by biofouling: cleaning by
oxidizing agents or by lyes, e. g. caustic-soda solution
Between the individual cleaning steps, the installation
has to be rinsed with water to avoid interactions between
the chemicals used.
The following cleaning strategy is described by way of
example:
1. displacement of the process water from the installation
2. cleaning by citric acid/hydrochloric acid at pH 3 to
detach inorganic layers, duration about 1 – 4 hours at
slightly increased temperature
3. intermediate rinsing with water, i. e. displacement of
the cleaning solution used in step 2
4. treatment by NaOCl/NaOH at pH 11 to oxidize
bacterial depositions, duration about 5 – 8 hours at
slightly increased temperature
5. final rinsing with water for complete displacement of
all chemicals from the system
6. the installation is again put into operation with
process water
The duration of the individual steps may vary depending
on the degree of contamination. It may also be necessary
to repeat one of these steps several time.
A.5.4.2.3
Planning of the installation
The installation is now planned based on the results of
the pilot phase. The working steps are as follows:
• analysis of the test data, determination of the perme-
ability [in L/(m2 �h�bar)] at the end of the expected
membrane service life at each point in the membrane
process, as the most important design parameter
• design of the installation considering the real operating
conditions of the membranes and modules used
• integration of the membrane process into the complete
process
297
AnnexA
A.5.5
Assessment criteria for the choice of a membrane
installation
After having followed the working steps described above,
the selection procedures carried out should be assessed
again before the installation is realized. The following
sections will serve the future operator as check list for his
own work and for the assessment of offers.
A.5.5.1
Technical assessment of a membrane process
concerning employment and completeness
A.5.5.1.1
Definition of the terms of reference
• Have the waste water constituents been sufficiently
specified and documented?
• Have the variations in quality and quantity of the
waste water been defined?
• Have rare or cyclically appearing conditions in the
production process been considered in the specification
of the waste water data?
A.5.5.1.2
Material and mass fluxes during operation
of a membrane installation
• Are the mass fluxes logical, i. e. is the total balance
exact? (sum influents = sum effluents! Figure A-8)
• Are the measuring devices available which are necessary
for balancing the operation of the installation?
• Is it possible to bridge periods of chemical cleanings by
internal measures or buffering tanks?
• Is the installation sized in such a way that it can cope
in adequate time with the additional amount of waste
water resulting from these cleanings?
• Are there problems with waste disposal (replaced
membranes, prefilters?)
• If yes, how high is the expense?
298
membrane installationwaste water inflow
treated water (permeate or filtrate)
concentrate
chemicals for operating
chemicals for chemical cleaning
resources (electric power, compressed air)
other consumables (filter substitute etc.)
waste water from chemical cleaning
waste water from backwashing
Figure A-8
Material and mass fluxes during operation of a membrane installation
Annex A
A.5.5.1.3
Utilization or discharge of the resulting products
• Does the treated water (permeate or filtrate) comply
with the standards for discharge into the sewer system
or the receiving water, or the standards for reuse?
• Is the quality concerning this aspect continuously
controlled?
• Can the concentrate stream be used internally, or does
it comply with the standards for discharge into the
sewer system or a receiving water?
• Does the recycling of waste water have effects on the
existing waste water discharge or on the existing waste
water installation (increase of the concentration)?
• Which method is used for the discharge of the waste
water from chemical cleaning of the installation?
A.5.5.1.4
Pretreatment
• Do the membrane modules/the membranes need a
pretreatment?
• Does this pretreatment consider the required
technology and costs?
• What happens if pretreatment breaks down
(emergency measures to protect the membranes)?
• Have precautions (measuring methods, safety filters)
been taken in case of insufficient pretreatment?
A.5.5.1.5
Technical realization
• How high is the degree of automation of the installation?
• Is it sufficient for operation?
• Is the installation offered capable of reacting to varying
quantities and compositions of the waste water to be
expected?
A.5.5.1.6
Redundancies
• What are the consequences to the operation of a break-
down of the complete installation for some hours/some
days? (discharge costs/discharge safety/production los-
ses/follow-up costs)
• Are the considered redundancies sufficient in light of
the costs arising from a breakdown of the installation?
A.5.5.1.7
References/similar applications
• Have examples already been realized which are similar
to this case?
• Does the offering company have references for the
membrane technology chosen, perhaps for similar
applications?
A.5.5.2
Operating costs
A.5.5.2.1
Equipment
• How high is the input power/the power consumption?
• How high is the consumption/the cost of compressed
air?
• How high is the consumption of additional water
(e. g. for chemical cleaning, backwashing)?
• Is the water available for these measures sufficient in
quantity and quality?
• Which chemicals are necessary for normal operation?
• Are these chemicals available in the company?
• Is the amount of chemical consumption known?
• How high are the annual costs for analyses?
A.5.5.2.2
Auxiliaries
• Service life/annual costs for possible prefilters (offer for
wearing parts available)
A.5.5.2.4
Service life and replacement of membranes
• How long is the service life of the membranes used?
Expected/guaranteed service life (guaranteed value at least
two thirds of the expected value?)
• Is a longterm offer for spare membranes available?
• Does it include the costs for the amount of work involved
in the replacement of the membranes?
299
AnnexA
300
A.5.5.3
Change of the conditions during operation of the
installation
A membrane process has not only to be assessed concern-
ing completeness, costs and process safety, but some
boundary parameters have also to be considered during
operation. Neglecting them may partly give rise to pro-
blems or damages. With existing installations, the follow-
ing observations have been made:
• corrosion of some components due to the change of
cleaning chemicals
• change of the composition of cleaning chemicals, e. g.
by change of the supply source
• change of the succession of cleaning steps
• change of the temperature during the cleaning process
• hydraulic changes in the inflow or inside the
installation, e. g. by decreasing pumping performance
• change of the inflow quality, e. g. by change of the load
or by additional constituents (use of process chemicals
from other suppliers or change of the production
process)
• change of the membranes (change of the membrane
supplier)
• insufficient maintenance of the measuring or analytical
instrumentation (e. g. pH electrodes)
This list of operating problems observed in the past
clearly shows that maintenance of a membrane installa-
tion is of high importance. Of course, changes to the
inflow quality cannot always be avoided because changes
in the production process are always possible. Slight
changes normally will not influence the treatment instal-
lation. Nevertheless, it is recommended to keep close con-
tact with the manufacturer of the membrane installation,
since important changes to the water inflow can often be
managed by slight modifications to the installation. Pre-
requisite is that the operator is informed immediately
about these changes by internal measures.
The pages 315 – 316 contain the bibliography of Annex A.5.
A.5.5.4
Other items
A.5.5.4.1
Failures
• Are spare membranes or modules available at short
notice in the required quantity, if necessary?
• Is this time acceptable for operation (possible break-
down of the installation for this period)?
A.5.5.4.2
Preliminary tests
• Have preliminary tests been carried out for this case or
application?
• If yes, are the indications of the offer in accordance
with the data from the preliminary tests?
A.5.6
Questionnaire for the acquisition of process data
A.5.6.1
Description of the separation problem to be
solved with the help of a membrane process
• What type of waste water will be treated? Origin?
Composition? Results from physical and chemical
analysis (among others temperature, pH value, electric
conductivity, disposition for fouling, solid matter
content, type of solid matter)
• Which components have to be removed from the
medium?
• What requirements are there for permeate quality?
• Does the medium contain substances which may
damage the membrane? (see list in the annex) If yes,
which substances?
• Is the medium microbiologically conspicuous?
Annex A
A.5.6.2
Concerning the assessment or the integration
of a membrane process into an overall treatment
concept
• Is there a possibility to reuse the permeate/filtrate and
the concentrate (e. g. reuse in operation, recovery of
reusable material)
• Which possibilities exist for the treatment of the con-
centrate, if necessary? Assessment of discharge paths
and costs?
• How important are the cost savings which possibly
result from the use of a membrane process? (chemicals,
water and waste water levies etc.)
• Which processes competing with the membrane
process have to be considered?
A.5.6.3
Sizing of the installation
• What waste water quantity is to be expected? How is it
produced? Are there mixing and equalizing possibilities,
if necessary? Future development? (graphs of quantities
and concentrations of the constituents, given in
m2/h, m2/d and m2/a)
• What is the minimum permeate output (= % related to
the treated water quantity) that should be obtained?
• Are there possibilities to influence the process
temperature?
A.5.6.4
Requirements for the construction of the
membrane installation
• What demands are made of the material to be used?
Are there materials which cannot or must not be used?
• What other demands are made of the membrane
installation? (e. g. flame protection, sanitary execution,
operation under food conditions, CIP capacity)
• Are there instructions for the degree of automation of
the installation or for the type of control device?
• How much space is available for a possible membrane
installation?
Annex
Depending on concentration and operating mode, the
following substances may have negative effects on the
performance of the system and have to be examined in
a more detailed way:
oxidizing agents [e. g. chlorine, peroxide, chromium(VI)],
cationic detergents, flocculants, defoamers, polymers,
silicones, organic solvents, silicates, calcium, barium,
strontium, iron/manganese, tin, acids/lyes (pH value),
gypsum, lime, abrasives.
Part II
Aerobic membrane bioreactor processes
A.5.7
General information
This work report addresses operators, planners and plant
manufacturers who deal with industrial waste water treat-
ment. It is the second part of the work report “Treatment
of industrial waste water and process water by membrane
processes and membrane bioreactor processes”, based on
the work report “Membrane bioreactor processes” for
municipal plants which presents the most important
basics and definitions.
In membrane bioreactor installations, the final clarifica-
tion stage is replaced by microfiltration or ultrafiltration.
From this result two important advantages:
• the effluent is free of solid matter,
• the biomass concentration is independent of the
sedimentation behaviour.
Therefore, membrane bioreactors are capable of reaching
much higher TS concentrations than conventional acti-
vated sludge plants. Tank volume can be saved to the
same extent, if the same design principles are applied.
Figure A-9 shows the flow sheet of a membrane bioreactor
compared to a conventional activated sludge plant.
301
AnnexA
This work report is divided into the description of the
construction of membrane bioreactors (chapter A.5.8),
and the quality requirements for the effluent (chapter
A.5.9). In chapter A.5.10, instructions for design are given,
and chapter A.5.11 deals with some special features of
membrane bioreactors compared to conventional activated
sludge processes. Chapter A.5.12 contains information on
the economic efficiency of membrane bioreactors. A list
of exemplary installations in the field of industrial waste
water treatment in Europe completes the report.
A.5.8
Construction
Membrane bioreactors consist of an aeration tank in
which the waste water is biologically treated with the
help of activated sludge and a filtration unit which serves
to retain the activated sludge by means of membranes
integrated into modules, so that the effluent is free of
solid matter.
A.5.8.1
Arrangement
The membranes and membrane modules available on the
market differ with regard to the module construction, the
molecular separation size (micro- or ultrafiltration mem-
brane), the membrane structure (flat, tubular and capillary
membranes), the filtering sense (inside-out or reverse),
the place of installation (dry-arranged or immersed
systems) and the operating mode. Because of the high
solid matter content of the activated sludge process, the
filtration unit of a membrane bioreactor is generally ope-
rated in cross-flow mode, i. e. the mixed liquor is fed
tangentially across the membrane surface; a partial flow
passes through the membrane and is withdrawn as filtrate.
The development of a covering layer can be influenced by
varying the overflow conditions. Compared to membrane
modules in a dry arrangement, immersed systems have a
lower specific energy demand for the generation of the
cross-flow, but larger membrane surfaces are necessary
because the flow rate [L/(m2 �h)] is also lower.
A.5.8.1.1
Immersed membrane modules
Immersed membrane modules are installed in the aerobic
part of the aeration tank or in a separate “filtration tank”
(Figures A-10 and A-11). The necessary cross-flow is gene-
rated by coarse-bubble aeration arranged below the mem-
branes and/or mechanical movement. The filtrate is with-
drawn by means of a vacuum of approx. 0.05 - 0.6 bar (as
low as possible).
A.5.8.1.2
Dry-arranged membrane modules
In dry arrangement of the membrane modules, the mixed
liquor is taken from the aeration tank and pumped
through the module. The cross-flow is generated by a
pump. Due to high pressure loss in the common modules,
the energy demand is higher than that of immersed sys-
tems. However, the covering layer control is very effective
so that a higher specific flow is obtained. Figure A-12
shows a diagram of this arrangement.
302
BB = activated sludge tank
NK = secondary settling tank
effluent
ÜSS = excess sludge
BBeffluent
ÜSS
inflow inflowBB NK
Figure A-9
Schematic comparison of the conventional activated sludge process with the membrane bioreactor process
Annex A
A.5.8.2
Control of the covering layer
A.5.8.2.1
Control of the covering layer in immersed systems
Immersed systems are installed directly in the aeration
tank or in an external filtration tank (cf. Figure A-10 and
Figure A-11). The covering layer is controlled by coarse
bubble aeration at the bottom of the modules. The rising
air bubbles generate innumerable small turbulences. By
pressure differences in these turbulences, particles attached
to the membrane surface are detached.
In hollow-fibre membranes, extensive movements of the
hollow fibres are generated by the large number of turbu-
lences. These movements can be supported by intermittent
aeration; the resulting pumping effect induces a cross-flow
inside the fibre bundle. This improved covering layer con-
trol has the additional advantage of minimizing the energy
consumption for air intake.
Concerning flat membranes, it is possible to generate a
forced air flow along the membrane by means of a fitting
(the membrane is cased in a box) or a mechanical move-
ment. With some systems, e. g. plate membranes, the re-
sulting air lift pumps the activated sludge in an effective
way only if a free up-flow channel is arranged below the
membrane to accelerate the air-sludge mixture.
A.5.8.2.2
Covering layer control in dry-arranged systems
In dry-arranged systems, filtration by the membrane
bioreactor process is carried out in cross-flow mode. By
tangential flow across the membrane surface on the side
of the solid matter, the development of a covering layer
is limited by deposition of filtered particles to obtain a
constant, high-level filtrate flow. The more permeable,
i. e. the thinner the filtering cover layer of the membrane,
the higher is the flow rate. To control the covering layer
as effectively as possible, several times the flow (feed) is
recycled. The typical velocity in cross-flow filtration is
approx. 1 – 4 m/s, depending on the module construction.
303
Figure A-12
Membrane modules in dry arrangement
Figure A-10
Arrangement of the immersed membrane modules
in the aerobic section of the activated sludge tank
Figure A-11
Arrangement of the immersed membrane modules
in an external filtration tank
AnnexA
A.5.8.2.3
General facts
The generation of the cross-flow is the main contributor
to the specific energy demand of membrane filtration.
The objective of a large number of process developments
is the reduction of energy consumption by minimizing
the cross-flow, while maintaining the same high flow
rate. Therefore, the membrane surfaces required, and
thus the investments and costs for membrane replace-
ment, are reduced.
Figure A-13 presents the theoretical relationship between
membrane surface area, energy demand and flow for the
membrane bioreactor processes.
A.5.8.3
Cleaning strategies
Cleaning of the membranes is necessary to take precau-
tions against a reduction of the flow [more exactly: of the
permeability, expressed in L/(m2 �h�bar) or to increase
the permeability in case of reduced throughput.
Permeability losses may have the following causes:
• deposition of (colloidal) organic and inorganic particles
• deposition and precipitation of salts (see scaling)
• deposition of organic macromolecules
• biofouling, i. e. penetration and growth of micro-orga-
nisms and/or their excretions such as enzymes, EPS
(extracellular polymer substances) in and at the
membrane
According to the diversity of causes, the cleaning strate-
gies have to be adapted to the waste water composition,
to the operating mode of the activated sludge stage and
to the membranes and membrane modules used.
One distinguishes between process-controlled integrated
backwashing, periodic in-situ maintenance cleanings, e. g.
by backwashing using chemicals, and irregular, disconti-
nuous main cleanings with chemicals for which the fil-
tration unit has to be shut down.
All cleaning processes proceed more quickly at higher
temperatures. Moreover, the same effect is obtained with
a lower chemical concentration, i. e. the cleaning process
is more gentle. Experience from large-scale testing of orga-
nic membranes has been acquired at cleaning temperatures
of 35 – 40 °C.
Since cleaning processes strongly depend on the type of
membrane and module and new cleaning processes are
continuously being developed, it is only possible to pro-
vide general information on membrane cleaning practices.
Rinsing/backwashing
Backwashing refers to a periodic reversal of flow in the
membranes to detach the particles adsorbed during the
filtration process (covering layer). In principle, the filtrate
is used for backwashing.
A typical operating regime for a commercially available
hollow-fibre module is a filtering duration of 5–8 minutes,
followed by a backwashing interval of approx. 30 – 40 sec.
[Remark: With this operating mode, one has to distinguish
between cross flow (flow during the filtration phase) and
net flow (i. e. the flow obtained from a complete sequence
of filtration and backwashing, taking into account the
backwashing volume)].
304
spec
ific
mem
bran
e su
rfac
e [m
2 /(m
3 ·h)
]
flow
[l/
(m2 ·
h)]
energy demand (kWh/m3)
surface
flow
immersedmembrane modules
dry-arrangedmembrane modules
Figure A-13
Qualitative relationship between necessary mem-
brane surface area, energy demand and flow
Annex A
Rinsing refers to shortterm operation with clear water
without flow reversal in order to wash away and to dis-
charge the covering layer. This procedure is used for dry-
arranged membrane modules.
Maintenance cleaning (chemical enhanced backwash)
For this (intermediate) cleaning, chemicals such as citric
acid or oxidizing chemicals (e. g. hypochlorite) are added
to the rinsing or backwash water. Cleaning is done in situ,
i. e. the membrane remains in contact with the mixed
liquor (the mixed liquor can also be drained off). The inter-
val between two rinsing cycles and the type of chemicals
and their concentration depends on the respective appli-
cation.
Typical intervals for maintenance cleanings, e. g. with
sodium hypochlorite (NaOCl) or acid, are from a few days
up to several weeks.
Rinsing is done with a very low backwash flow rate (often
in a cycle of short rinsing – leaving on – rinsing, which is
repeated several times) to minimize the introduction of
chemicals and undesired formation of pollutants (AOX).
Intensive cleaning
Depending on the application, an intensive cleaning may
be necessary from between once a month up to twice a
year. For an intensive cleaning the membrane modules are
put into a separate cleaning tank or the mixed liquor is
withdrawn and substituted by cleaning solutions.
The type of cleaning chemicals used depends on the appli-
cation. The cleanings should be carried with hot water. A
typical cleaning sequence may comprise the following
steps:
• rinsing of the membranes with water
• treatment by acids, e. g. citric acid (250 – 2,000 ppm)
with addition of hydrochloric acid or sulphuric acid to
adjust the pH value to 2 – 3, in order to detach/remove
inorganic depositions
• intermediate rinsing (neutralisation) to avoid salt depo-
sitions and heat development in the membrane (neutra-
lisation heat), if the following cleaning step takes place
at alkaline pH values
• cleaning by oxidizing chemicals to oxidize organic and
bacterial depositions, e. g. by a solution of 0.05 %
(weight percent) (= 500 ppm (500 mg/L) related to active
chlorine), i. e. a NaOCl solution of approx. 0.4 %
(= 4,000 ppm NaOCl) at pH 11 for an exposure time of
5 – 20 h; if necessary, at high temperature.
• final rinsing with water to wash out the caustic soda
solution (NaOH). This reduces the scaling potential and
the risk of saponification (reaction of NaOH with grease
and oil to glycerol and Na salts of the fatty acids, which
might lead to undesired foam development).
In general, the cleaning solution should be purged from
the system, depending on the degree of contamination of
the membranes.
Cleaning – instructions and experiences
Given the large number of membrane applications and the
variety of membranes and membrane modules, it must be
stated that cleaning concepts and experiences cannot be
transferred from one case to another. However, the follow-
ing general instructions should be considered:
• Cleaning chemicals, especially when concentrated, may
affect membranes, back-up tissue of the membranes,
components of the membrane modules, and tank walls
and instruments.
– This is especially true for low and high pH values. It
has to be considered that due to chemical reactions,
higher pH values may locally occur than measured/
calculated in the reactor (example: increase of the
pH due to the oxidation of organic matter by sodium
hypochlorite).
• Oxidizing chemicals attack organic membranes and
lead to accelerated aging. The more aggressive the che-
micals, the higher the concentration, and the longer
the expo-sure time, the more acute is the damage to
the membrane. Some membrane manufacturers give
chemical-specific maximum values for the product of
chemical concentra-tion and exposure time. Example:
250,000 ppmh of free chlorine mean 500 h with a solu-
tion concentration of 500 ppm, or 100 h with a solu-
tion concentration of 2,500 ppm.
305
AnnexA
• Due to chemical reactions, cleaning chemicals themselves
may give rise to disturbances or may form harmful
substances. Examples:
– saponification, by reaction of NaOH with greases and
oils " intense foam development. Measure: sufficient
rinsing with water
– salt deposition in the membrane by neutralisation
reactions. Measure: sufficient intermediate rinsing
with water
– AOX formation by reaction of OCl– with organic
constituents. Measures: utilization of drinking water
(instead of filtrate) to prepare the cleaning solution;
utilization of halogen-free oxidants such as H2O2,
peracetic acid (the cleaning effect has to be examined!)
• Cleaning solutions have to be duly stored; if necessary,
they can be processed and reused several times. All safety
regulations concerning the handling of chemicals have
to be observed.
• The cleaning solutions have to be duly discharged.
(In principle, they can be fed into the activated sludge
stage – to be examined!)
• During planning it has to be assessed whether the
necessary intensive cleanings shall take place in situ or
in an external tank. This has consequences for the costs,
for the material choice (e. g. tank coatings, fittings) as
well as for the logistics of removal and transport of the
membrane, feasibility of cleaning at higher temperature,
flexibility in the choice of chemicals, etc.
• The concentrations of cleaning solutions should be
indicated as exactly as possible. Especially when using
hypochlorite, it must be indicated whether the concen-
tration value is related to NaOCl, HOCl, OCl–, the
calculated Cl content or the free (active) chlorine. For
the conversion from litres into kg, weight percent or
ppm, it is necessary to consider the density of the
commercial NaOCl solution (chlorine bleaching lye)
of � = 1.2 kg/L. The solution contains maximally
12 – 13 % of effective (free, active) chlorine.
• It is useful to coordinate the details of the cleaning
processes with the membrane supplier (manufacturer)
and to record the results of each cleaning. Membrane
guarantees should include agreement about cleaning
concepts, intervals and parameters to be recorded.
A.5.9
Requirements for the influent
A.5.9.1
General information
Before feeding waste water to a membrane bioreactor, it
is necessary to remove undesired material such as long
fibres and filamentous or strongly abrasive, sharp-edged
substances because they may clog the modules or mecha-
nically destroy the membranes.
In addition, it must be considered that dissolved waste
water constituents may also damage the membranes. If
necessary, membrane-typical specifications (limit values)
have to be taken into account. This concerns not only
the organic (non-degradable) solvents contained in the
waste water, but also substances which are added in waste
water treatment, e. g. defoaming agents (have to be free
of silicone!) and organic polymers. For the specific appli-
cation, the experiences of manufacturers and suppliers
should be used.
A.5.9.2
Mechanical pretreatment
Screens
Fibrous, sharp-edged and agglomerating material has to
be prevented from entering from membrane bioreactors.
The composition of the waste water from different indus-
trial branches may vary considerably as to the content of
those substances. Large quantities of fibres, as present in
municipal waste water, only occur in the waste water of
few branches. Screens with an aperture size of 0.5–2 mm
or slot sieves with a slot size of 0.5 –1 mm are normally
sufficient. If a pretreatment stage is arranged upstream, a
screen mainly has a protecting task.
Separator for grease and light-density material
Undissolved, hardly degradable greases and oils have to
be removed from the waste water before it is fed into the
membrane bioreactor because they may have a negative
effect on the filtrate performance. Well degradable greases
and oils do not give rise to problems.
306
Annex A
Primary treatment
Primary treatment should be planned in the case of high
solid matter contents in order to maintain a sufficient frac-
tion of active biomass in the activated sludge, so that the
biological treatment capacity is not negatively influenced.
A.5.9.3
Mixing and equalizing tank
With membrane bioreactors, hydraulic compensation is
of importance. The membrane surface area has to be de-
signed, proportionately to the secondary treatment, for
the maximum water quantity. Since large membrane sur-
faces are very expensive and an increase in the through-
put rate in the case of larger waste water volumes is pos-
sible only to a rather limited extent, it is useful to equal-
ize the waste water flow. For this purpose, volume-equal-
izing tanks are suited, independent of considerations
concerning the equalization of concentrations.
If the waste water volume varies only slightly, the necessary
storage volume can be made available in the tank itself,
since impoundment is also possible in the aeration tank
to a limited extent.
A.5.9.4
Calcium concentration
Increased Ca2+ concentrations (> 200 mg/L), either from
the use of calcium in the production process, from up-
stream precipitation processes, or from neutralisation of
acid waste water by lime milk, may be problematic for the
membranes. Due to the high air intake which provides
turbulent flow for immersed membranes, a large part of
the CO2 formed in the aeration tank is stripped out. As a
result, the pH value rises (keyword: lime-carbon dioxide
balance, solubility product), which may lead to a reduc-
tion in the filtration capacity. Consequently, the mem-
branes have to be cleaned more frequently.
A.5.9.5
Iron and aluminium content
Partial flows of various industrial branches may contain
iron and aluminium salts. They are frequently used as
precipitants to support primary treatment, and they may
also be present in the process waste water flow itself.
Oxidized forms and particular compounds have no in-
fluence on the membrane and the filtration characteris-
tics. Dissolved compounds, which under aerobic condi-
tions are oxidized in an activated sludge stage, may give
rise to depositions. Oxidation partly takes place directly
on the membrane so that the undissolved precipitation
product sticks to the surface. The resulting visible colora-
tion can be removed, if necessary, by acid cleaning.
A.5.10
Instructions for the design of membrane bioreactors
A.5.10.1
General information
The biological degradation of organic matter in membrane
bioreactors does not differ fundamentally from the pro-
cess in conventional installations, i. e. these substances
oxidize to CO2 and are used for cell growth. The biomass
developed accumulates as excess sludge together with the
input of non-degradable and insoluble particulate sub-
stances (chapter A.5.11.1.3).
However, membrane bioreactors differ from conventional
installations in particular by the high TS content in the
aeration tank (usually 10 – 20 g/L, conventional instal-
lations: 3 – 5 g/L) and the resulting change in the sludge
characteristics. While aeration tank volumes are calculated
according to the load to be degraded, the membrane sur-
face area is determined, correspondingly to the secondary
settlement tank, according to the hydraulic throughput.
Because of higher expense for the filtration unit, hydrau-
lic design has to be performed with the utmost care
(cf. chapter A.5.12).
307
AnnexA
Comparisons of operating results of membrane bioreac-
tors by theoretical models have shown that the sludge
yield can be assessed rather well, especially by detailed
models such as the Activated Sludge Model of the Inter-
national Water Association, but also with simpler ap-
proaches, provided that the specific boundary conditions
of the respective industrial waste water are sufficiently
considered. With high sludge ages, it is recommended to
perform the calculation on the basis of the maintenance
metabolism [WICHERN AND ROSENWINKEL 2002].
The references available show that the current engineering
design based on semi-technical preliminary tests is the
basis for a large number of well-functioning installations.
A.5.10.2
Space requirements
In industrial waste water treatment, the space requirement
of an installation is often a decisive criterion. For new
industrial settlements, space requirement for waste water
treatment can often be alloted. However, for industrial
enterprises which have grown for decades it is often im-
possible to integrate waste water treatment on their fac-
tory sites.
Compared to a conventional activated sludge plant, the
required aeration tank volume can be reduced to approx.
one half or even one quarter; moreover, secondary treat-
ment is no longer necessary. Therefore, the space require-
ment for the waste water treatment plant is significantly
reduced. This is often a decisive advantage for industrial
enterprises and enables them to treat their waste water
on their facilities.
A.5.10.3
Elimination rates
An operating mode with low excess sludge production
requires attention to the considerably higher oxygen re-
quirement, the effluent quality, and the possible accumu-
lation of harmful and inhibitory substances in the acti-
vated sludge.
The specific oxygen requirement increases with decreas-
ing sludge loading, i. e. with decreasing specific excess
sludge production. This is because in this operating mode,
the organic matter has to be oxidized to CO2 to a greater
extent [CORNEL 2000].
The increased operating TS concentration in a membrane
bioreactor results in one of two design scenarios relative
to conventional activated sludge treatment:
• smaller aeration tank volumes with equal sludge
loading and equal excess sludge production, or
• equal aeration tank volumes and lower sludge loading
with less excess sludge, but higher energy costs.
It is not possible to realize all “positive” features – low
energy demand, reduced excess sludge production and
smaller aeration tank volumes – in the same installation,
because these features, in part, are mutually exclusive.
The impact of an operating mode with low excess sludge
production, i. e. low sludge loading rate, on the effluent
quality (“refractory substances”) has to be determined for
each case. The extent of removal of refractory compounds
depends on the waste water constituents and the operating
conditions (sludge age). Ultra- and microfiltration mem-
branes do not reject low-molecular weight substances.
However, increased degradation of slowly degradable sub-
stances is possible at high sludge ages along with possible
retention of macromolecules by the covering layer. Con-
stituents attached to particles, e. g. adsorbed AOX com-
pounds, are rejected by the membrane installation.
Compared to conventional activated sludge plants, load-
peaks have a stronger effect on the effluent quality. This
is due to reduced dilution because of the smaller aeration
tank volume. In general, it is true that loadpeaks are
more difficultly to manage at very low sludge loading
rates [F/M < 0.03 kg BOD5/(kg TS �d)], due to the lower
biomass activity.
Inhibited degradation due to the accumulation of heavy
metals in the activated sludge is observed in some indus-
trial branches. In cases where there exists increased heavy
metal concentrations in the waste water, the sludge age
in membrane bioreactors has to be carefully controlled
especially.
308
Annex A
Phosphorus elimination in membrane bioreactors can be
realized very easily by simultaneous precipitation with
iron salts. Since ultrafiltration is able to absolutely reject
very small particles, better effluent quality can be obtained.
In this case, the molar ratio can be set more favourably.
By adaptation of the cleaning strategies and the cleaning
agents, it is possible to counteract the adsorption of pre-
cipitant residues on the membrane surface. Membrane
filtration itself is not normally influenced by regular pre-
cipitant dosing. If the installation is correspondingly de-
signed, biological phosphorus removal is also possible
when the sludge age is designed in the appropriate range.
Membrane filtration produces solidsfree water which is
disinfected to a great extent. With conventional mecha-
nical-biological processes it is not possible to reach
comparable effluent quality, even if a conventional filtra-
tion process, e. g. sand filter, is arranged downstream.
A.5.10.4
Aeration
The mass transfer of oxygen from the gas phase into the
liquid phase is influenced by, among others, the parameters
salt concentration, viscosity of the medium, surface-active
substances, surface tension, solid matter content, aeration
system, turbulence, and pressure (water depth). A general
guide value of oxygen input and �-values cannot be
given for industrial (membrane) bioreactors. In industrial
waste water treatment plants with conventional biological
processes, �-values of > 1 may also occur due to various
waste water constituents, and, above all, because of high
salt concentrations (> 5 g/l). These have positive effects
on the oxygen transfer due to their coalescence-reducing
effect. However, the oxygen input also depends on the
dynamic viscosity which itself is strongly dependent on
the sludge concentration. Therefore, lower �-values than
in conventional activated sludge plants have to be expected
with high TS concentrations. Relatively high �-values
compared to municipal applications can be expected
with higher salt concentrations.
The transfer of air or pure oxygen is also possible by
means of injector systems. In the case of waste water
which tends to deposits, it should be taken into account
that the pH value will increase in intensely aerated zones.
This is due to stripping of CO2, which on the contrary,
may enrich during aeration with pure oxygen and conse-
quently resulting in reduced CO2 discharge.
When transferring the results of oxygen transfer measure-
ments in semi-technical or laboratory scale to large-scale
installations, it has to be considered that the fluid-dynamic
parameters can be represented and transferred only to a
limited extent. Oxygen transfer measurements should be
carried out at test installations with the waste water to be
treated, the design sludge concentration, and the design
liquid depth.
A.5.10.5
Hydraulics
A.5.10.5.1
Flexibility
The modular construction of membrane installations allows
adaptation to flow variations by switching on or off single
modules. In low flow events, it is more energy-efficient
to switch off single modules than treating the entire flow
through the complete membrane system. If the waste water
volume is consistently higher than designed, the modular
construction facilitates easy upgrading and adaptation to
the new requirements. In planning as well as during oper-
ation, great importance has to be attached to distribute
the flow as uniformly as possible to both modules.
A.5.10.5.2
Recirculation
The activated sludge concentrates on the membrane due
to filtrate withdrawal. If immersed membranes are
directly installed in the aeration tank, concentration distri-
bution by a mixing device is a sufficient compensating
measure.
If the membranes are installed in separated tanks or
arranged dry, sufficient recirculation has to be ensured.
In general the recirculation rate should be four or five
times the filtrate quantity which is being discharged. In
filtration tanks with immersed modules, the mixed liquor
feed and recirculation discharge should be at opposite
ends of the tank in order to avoid short-circuit flows.
309
AnnexA
In the case of immersed membranes, the recirculation flow
is oxygenated. This has to be taken into account if this flow
is to be recycled directly into the denitrification reactor.
A.5.10.6
Influence of the temperature
As a result of biological degradation in waste water treat-
ment, the bulk liquid temperature rises by approx. 2–3 °C
per gram of COD degraded per litre. This rise in tempera-
ture has to be taken into account, if necessary, in the
treatment of high-strength industrial waste water. How-
ever, with low organic loads this does not give rise to
problems. For dry-arranged systems, a rise in temperature
in the aeration stage may also be expected due to the
energy input of the mechanical equipment, e. g. the
pumps for cross-flow generation.
Concerning the flow characteristics, higher temperatures
are quite favourable for the use of membranes. For acti-
vated sludge plants the temperature has to be limited to
37 – 39 °C.
A.5.11
Specific features of membrane bioreactors
A.5.11.1
Sludge features
A.5.11.1.1
Characterization of the sludge
Due to an increased solid matter content, the sludge fea-
tures differ considerably from those of activated sludge
from conventional plants. The strong shear forces occur-
ring in cross-flow installations are responsible for an in-
crease in the abundance of single bacteria in microscopic
analysis. According to the biotic community, which de-
pends on the waste water quality, the sludge can be vis-
cous or thick, but may also have the consistency of a gel.
With high solid matter content, inclusion of oxygen bub-
bles may occur. As a rule, the viscosity is higher com-
pared to conventional activated sludge. The solid matter
contents are
• with immersed modules:
10 – 15 g TS/L and
• with dry-arranged modules:
up to 30 g TS/L
The dry matter content cannot be correlated directly
with the viscosity and the filterability. However, within
an installation it can be used as indicator.
A.5.11.1.2
Rheological properties
Activated sludge shows a more or less distinct shear thin-
ning, i. e. the viscosity decreases with increasing shear
load. The viscosity of the activated sludge which devel-
ops in the membrane bioreactor depends on many fac-
tors, including the size and structure of the sludge flocs,
composition of the waste water, the TS concentration as
well as the organic part of the TS concentration, and the
physiological properties of the biology [e. g. formation of
extracellular polymeric substances (EPS) under certain
operating conditions], e. g. floc stress due to forced circu-
lation. Therefore, simple correlation between viscosity
and TS concentration of activated sludges from different
installations is not possible.
If the relationship between the viscosity and the TS con-
centration of the biology shall be used as an auxiliary
parameter for the description of mass transfer (i. e. of the
oxygen intake), it has to be determined individually for
each installation/each waste water and, if necessary, also
for each sludge loading. Moreover, due to the more or
less distinct shear thinning properties of the activated
sludge, the viscosity in the settling tank is not homoge-
neous, but appears dependent on the local shear stress
condition. Thus, each statement on “the” viscosity of an
activated sludge is useful only if the respective shear load
(shear rate D in s-1) is defined.
Consistency, number of free bacteria, floc structure, inert
fraction etc. have a great influence on the filterability of
the activated sludge. Although the filterability within one
installation may possibly correlate with the TS concentra-
tion, this parameter is too inexact for the design of the
required membrane surface area. For this purpose tests
have to be carried out.
310
Annex A
The survey of rheological properties by continuous
measurement of the viscosity at a certain shear load or
the measurement of flow curves, may represent for mem-
brane bioreactors – combined with TS determination and
the regular assessment of the biocenosis by microscopic
analyses – a useful completion of the process parameters
for the control of the installation (cf. GÜNDER 1999;
KRAUSE ET AL. 2001).
A.5.11.1.3
Excess sludge production
Sludge production results from the growth of heterotrophic
and autotrophic biomass as well as from the biologically
inert fraction of the solid matter inflow and the inert
material resulting from the death of the biomass. While
the organic part at infinitely high sludge age may be nearly
completely biodegraded (at least in theory), the insoluble,
particulate, mineral part remains in the aeration tank and
has to be withdrawn as excess sludge. Since with usual
system settings the growth rates are higher than the death
rates, the excess sludge contains an organic part.
The same principles as for all activated sludge processes
are valid, i. e. the sludge output decreases with
• decreasing sludge load, i. e. increased sludge age
• decreasing solid matter input and
• rising temperature
Industrial waste water often has high temperatures and
low solid matter contents. For this reason the excess
sludge production rate, related to the treated load, is
often lower in the treatment of industrial waste waters
than in municipal applications. This tendency is reinforced
by the use of a low-loaded membrane bioreactor design.
For the activated sludge process, the excess sludge with-
drawn represents an accumulation medium for non-
degradable, but sorbable substances. If this withdrawal
does not take place, the substances are either found in
the filtrate or they accumulate – as far as they cannot
pass through the membrane – in the system. Several non-
degradable substances have a biologically inhibiting
effect or are toxic for bacteria when they exceed certain
threshold concentrations. For this reason regular excess
sludge withdrawal should be integrated into the design.
A.5.11.1.4
Sludge treatment
In principle, all systems available on the market can be
used for sludge dewatering. Optimal mixing of the poly-
mers, due to the increased viscosity of the excess sludge
at high TS concentrations, has to be considered in the
design.
According to the waste water situation, it may be useful
not to treat the excess sludge separately, but to dewater it
in a mixture together with the primary sludge. In this
manner the consumption of conditioning agents may be
reduced. It could be observed that the addition of e. g.
used activated carbon, which has to be discharged any-
how, may have positive effects on the dewatering beha-
viour. This is possibly also true for other structure-for-
ming additive substances.
In each case, attention should be paid to using membrane-
compatible polymers for sludge dewatering. They should
be tested on laboratory and technical scale.
A.5.11.1.5
Foam development
The pressure differences necessary for dry-arranged mem-
branes as well as the flow conditions may lead to consid-
erable stress on the biocenose and, with this, to increased
EPS development. In combination with intensive aeration,
this may result in considerable foam development.
Construction measures to control foam are, for example,
flat tanks with a large surface area (more advantageous
compared to slim tanks), and mechanical or physical
destruction of the foam. When using defoaming agents,
their membrane compatibility has to be ensured.
311
AnnexA
A.5.12
Economic efficiency
A.5.12.1
Definition of economic efficiency
Although the term “economic efficiency” is always used
in technology and economy, there is no general definition
that can be applied. It is necessary to define economic
efficiency for each single case. However, membrane bio-
reactors will be applied in all probability in the case of
corresponding demands on the effluent quality. Therefore,
a reference value related to other waste water treatment
processes can be defined: “The membrane bioreactor pro-
cess is more profitable than a conventional process if the
cash value (or capital value) of the discounted expense
after X years is similar to or higher than the cash value of
the alternative processes at comparable treatment results.”
ATV-DVWK recommends calculating the cash value; in
industrial practice, calculation of the capital value is more
frequent. However, both methods only differ in the fact that
in the first case one considers the time of commencement
and in the other case the end of the respective period.
Calculation of the cash value requires knowledge of the
expense for financing the investment (interest and amor-
tization) as well as the operating costs for one year and the
following years. The type of financing of the acquisition
and the expected service life (of installations, machines and
spare parts) have an effect on the part of fixed costs. The
operating costs mainly comprise energy and cleaning costs,
costs for membrane replacement as well as for manpower,
auxiliaries, etc. The costs avoided may possibly be included
into the assessment (e. g. for saved space, further treatment
steps, improved effluent quality, etc.). The process engi-
neering determines not only the amount of fixed costs,
since type and size of the installation determine the invest-
ment volume and thus the size of annual charges, but also
the variable costs. The membrane surface area chosen, the
number of modules (and the reserve supply), and the re-
sulting reactor volume required determine the amount of
investments. The operating mode determines the energy
consumption, personnel and cleaning costs. The follow-
ing aspects have an effect on the costs:
A.5.12.2
Investment/capital costs
The working life and the depreciation time of the indivi-
dual components have an important impact on the capital
costs of membrane bioreactor processes. The planner has
to elaborate suggestions according to the information from
the membrane manufacturer; the client has to make the
decisions.
The greatest influence on the capital costs include the
tank volumes, and the membrane surface area. The mem-
brane surface area required (and the surface area kept in
reserve) is determined by the choice of the process. In
general, the choice of a smaller separating surface area
leads to higher energy and cleaning costs (see also Figure
A-13). With immersed modules, larger membrane surface
area is necessary than with dry-arranged ones, since the
specific flow rate [L/(m2 �h)] is lower.
While the specific costs of aeration and final sedimentation
tanks rise only in a degressive way with increasing plant
size, the costs for the filtration unit of the membrane
process increase nearly in a linear way (costs per module).
The space requirement is often a decisive criterion for the
use of a membrane installation. Reduction of the necessary
aeration tank volume to approx. half or a quarter compared
to a conventional activated sludge plant, and due to the
fact that final sedimentation becomes unnecessary, the
space requirement, and thus the capital costs, are consider-
ably minimized. In spite of space reduction for activation,
one must not neglect that in some cases space is required
for mixing and compensation tanks, and possibly also for
cleaning tanks.
312
Annex A
313
A.5.12.3
Operating costs
Energy costs
The generation of a flow across the membrane is the main
contributor to the specific energy demand of membrane
filtration plants. The objective of numerous process de-
velopments is the minimization of the energy consumption
by reducing the amount of energy necessary for control
of the covering layer (flow across the membrane), while
maintaining high specific flow rates to minimize the ne-
cessary membrane surface area (examples: rotating modu-
les, oscillating modules etc.).
Compared to dry-arranged membrane modules, the gene-
ration of a cross-flow with immersed systems requires less
energy; about 0.5 – 1.5 kWh/m3 are required for covering
layer control of immersed modules and 1 – 4 kWh/m3 are
needed for dry-arranged systems.
Cleaning costs
The type of cleaning and the cleaning intervals strongly
depend on the waste water quality, but also on the type
of membranes and modules. Therefore, no generalized
specific costs can be given. Besides the chemicals required,
inclusive of their storage, the personnel costs, the energy
costs for heating of the cleaning solutions and, if neces-
sary, the discharge costs have to be taken into account.
According to the type of cleaning, additional investments
for separate cleaning tanks, including the necessary lifting
and transport facilities, or special chemical-resistant coat-
ings of the filtration tanks may become necessary.
Membrane replacement and membrane disposal
costs
The service life of membranes depends on different factors,
such as:
• type of the waste water
• type and frequency of cleaning
General service lives or disposal costs cannot be indicated.
However, membrane replacement and membrane dispo-
sal costs have to be taken into account.
AnnexA
314
Branch/application Total number Number of Number of dry- Flow rate m3/d
immersed installations arranged installations
Table A-5
Membrane installations in West European industry
Solid waste treatment ≥ 1 ≥ 1 – 140
Car industry ≥ 1 ≥ 1 – 230
Chemistry ≥ 15 ≥ 7 ≥ 8 50 - 1,400
Landfill for municipal waste ≥ 48 ≥ 9 ≥ 39 10 - 900
Print shops ≥ 1 – ≥ 1 25
Groundwater rehabilitation ≥ 1 – ≥ 1 20
Cosmetics industry ≥ 3 ≥ 3 - 120 - 700
Laboratory water ≥ 1 – ≥ 1 10
Food industry ≥ 9 ≥ 4 ≥ 5 100 - 480
Leather production/tanneries ≥ 5 ≥ 3 ≥ 2 30 - 820
Malthouse ≥ 1 ≥ 1 ≥ 1 100
Pharmaceutical industry ≥ 15 ≥ 14 ≥ 1 50 - 1,500
Ships’ waste water ≥ 15 ≥ 5 ≥ 10 4 - 740
Tank cleaning ≥ 1 ≥ 1 – 200
Textile industry ≥ 5 ≥ 3 ≥ 2 100 - 1,500
Animal waste processing ≥ 4 ≥ 3 ≥ 1 427 - 960
Laundries ≥ 5 ≥ 1 ≥ 4 30 - 820
A.5.12.4
Comparison of cost-relevant factors
The following factors improve the economic efficiency
compared to conventional plants:
• high influent concentrations
• low concentration of substances causing scaling
and/or fouling
• high costs for the building site
• constant hydraulic load
• high demands on the effluent quality
• reutilization of the treated waste water
Compared to conventional activated sludge plants, mem-
brane bioreactors may be more cost-effective if the influent
concentration is high, and the volume flow is small and,
in particular, very constant.
A membrane bioreactor process will always be considered
if the demands on the effluent are high or if the water
shall be reused, e. g. as process water.
If the filtrate can be reused, saved waste water charges
– for indirect dischargers: saved effluent charges –
according to the waste water statutes and saved freshwater
costs have to be included in the economic analysis.
Annex A
315
A.5.13
Examples in the field of industrial waste water
(Europe)
Without claiming to be complete, Table A-5 summarizes
exemplary applications of membrane bioreactors in
Western Europe. The examples come from the reference
lists of the manufacturers and plant contractors, complet-
ed by the knowledge of the work group members. Test
installations have been or are being operated in a large
number of other branches.
Pages 315 – 316 contain the bibliography of Annex A.5.
A.5.14
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der Wasseraufbereitung und Abwasserbehandlung – Pers-
pektiven, Neuentwicklungen und Betriebserfahrungen im
In- und Ausland, Begleitbuch zur 4. Aachener Tagung
Siedlungswasserwirtschaft und Verfahrenstechnik.
Peters, Th. (1998): Wasseraufbereitung mit Membranfil-
trations-Verfahren. Umwelt Bd. 28, Nr. 4, S. 34 – 39.
Peters, Th. (2001): Möglichkeiten und Grenzen der Mem-
branverfahren aufgezeigt an internationalen Beispielen.
Handbuch Fachveranstaltung „Membranverfahren in der
industriellen und kommunalen Abwassertechnik“, Haus
der Technik, 22. – 23. November, Berlin.
Annex A
317
A.6
2nd Work report of the DWA Committee of
Experts KA-7 “Membrane bioreactor process“
from 19th January 2005
This second working report has been prepared by the
DWA Committee of Experts KA-7 “Membrane bioreactor
process“. The committee includes the following people:
Dipl.-Ing. Eberhard Back, Ulm
Dipl.-Biol. Evelyn Brands, Düren
Dr.-Ing. Elmar Dorgeloh, Aachen
Dipl.-Ing. Kinga Drensla, Bergheim
Prof. Dr.-Ing. Franz-Bernd Frechen, Kassel (chairman)
Dr.-Ing. Werner Fuchs, Tulln
Dipl.-Ing. Regina Gnirß, Berlin
Dipl.-Ing. Karl-Heinz Greil, Kundl
Prof. Dr.-Ing. Karl-Heinz Rosenwinkel, Hannover
Dr.-Ing. Wernfried Schier, Kassel
Prof. Dr. rer. nat. Dirk Schoenen, Bonn
Dipl.-Chem. Simone Stein, Leipzig
Prof. Dr.-Ing. Ulf Theilen, Gießen
Dipl.-Ing. Helle van der Roest, Amersfort
Dr.-Ing. Klaus Voßenkaul, Aachen
Dipl.-Ing. Detlef Wedi, Braunschweig
Dipl.-Ing. Thomas Wozniak, Gummersbach
Dipl.-Ing. Petra Zastrow, Merseburg
and guests.
A.6.1
Introduction
Since the publication of the 1st working report on the
membrane bioreactor process [ATV-DVWK 2000b], the
knowledge of this technology has increased due to further
operating experience with large-scale installations and
research projects. This 2nd working report takes the con-
tents of the first report, completes them and describes
the findings from the operation of large-scale installations.
It is now possible to specify design parameters such as
oxygen input with the help of data from large-scale ap-
plications. The following subjects are covered:
• pretreatment of the raw waste water,
• chemical cleaning,
• sludge treatment,
• energy consumption,
• commissioning,
• membrane bioreactor process for the upgrading of
waste water treatment plants and
• reference information on the costs of membrane
bioreactors.
It must be noted that at present membrane technology is
developing at a high speed, in particular in the field of
municipal waste water treatment. This is reflected not
least by the high frequency of meetings of the Committee
of Experts. Therefore the content of this second work
report, too, will certainly soon be supplemented by new
findings.
The next document of the Committee of Experts will be
an advisory leaflet which will probably be published in
2006.
AnnexA
318
A.6.2
Description of the membrane bioreactor process
Principle
The combination of an activated sludge tank and mem-
brane filtration for the separation of the activated sludge
is called the membrane bioreactor process. The membrane
filtration takes over the separation of the activated sludge
in place of the conventional final clarification. While in
secondary settling tanks only the part of the activated
sludge that is settleable is separated, i. e. forms setlleable
flocs, during membrane filtration all parts of the activated
sludge are separated which are larger than the molecular
separation size of the membrane. Thus, the separation of
the activated sludge from the treated waste water becomes
independent of the settling characteristics of the activated
sludge and depends only on the membrane applied.
To separate the activated sludge with its micro-organisms
and particles from the treated waste water, microfiltration
membranes with a molecular separation size of maximally
0.4 µm are used for the membrane bioreactor process.
Concerning the arrangement of the modules, two varia-
tions can be distinguished for the membrane bioreactor
process.
• Membrane bioreactor process with dry-arranged
membrane filtration
Membrane filtration takes place downstream of the acti-
vated sludge tank in an external, closed filtration unit.
The modules (e. g. tube modules) are set up in a dry ar-
rangement (see Figure A-14). The activated sludge is
pumped through the modules, which results in higher
pressures (more than 1 bar) with this process.
Up to now, this external membrane filtration is not found
at municipal plants and therefore not a subject of this
work report. Information is available in the work report
IG 5.5 Part 2 [ATV-DVWK 2002].
feed permeate
activated sludge tank
excesssludgeconcentrate (return sludge)
membrane filtrationin dry arrangement
Figure A-14
Membrane filtration in dry arrangement
Annex A
319
• Membrane bioreactor process with immersed
membrane filtration
In this variation, the membrane modules are placed in the
mixed liquor. The membrane modules can be installed
either in the activated sludge tank or in a separate filtra-
tion tank. Figure A-15 shows both configurations.
For proper functioning of the membrane bioreactor pro-
cess, the following basic requirements have to be fulfilled:
• Oxygen supply to the activated sludge,
• circulation and thorough mixing of the activated sludge
tank,
• transmembrane pressure difference as a driving force
for the filtration process,
• control of the development of a covering layer.
With immersed arrangement, the overflow necessary for
covering layer control is typically generated by coarse-
bubble aeration. For this purpose, a blower with air inlets
under the immersed membrane modules and a suited flow
control to generate the overflow are necessary. Separate
aeration in the activated sludge tank is required besides
module aeration.
The transmembrane pressure difference can be generated
by a permeate pump or hydrostatically. In principle, the
lowest possible transmembrane pressure is favourable in
operation.
feed permeate
activated sludge tank
excesssludge
cross-flowaeration
membrane filtration
feed permeate
activated sludge tank
filtrationtank
cross-flowaeration
membrane filtration
excess sludge
concentrate(return sludge)
A) immersed membrane filtrationin the activated sludge tank
B) immersed membrane filtrationin a separate filtration tank
Figure A-15
Ways of configuring an immersed membrane filtration
AnnexA
320
Constructional forms and operating modes
Up to now, the following membranes have been used in
large-scale applications of the membrane bioreactor
process:
• plate membranes and
• hollow-fibre membranes
Membranes are used as modules in different construc-
tional forms.
Plate modules are assembled from membrane plates
which are arranged in parallel. They consist of a support-
ing plate with a drainage device. The plate membrane is
fitted for the most part on each side of the membrane.
The flat membranes are overflown by the mixed liquor
and filtration takes place from outside to inside.
The permeate is withdrawn from the inside of the plate
by a suction duct.
Hollow-fibre modules consist of membrane hollow fibres
which may be reinforced by an in-side supporting tissue.
Filtration takes place from outside to inside. For module
assembling, a larger number of fibres are combined to form
a bundle, and are potted with resin at one or both ends.
A permeate collecting tube connects all of the individual
fibres. Depending on the manufacturer, the hollow-fibre
membranes are installed horizontally or vertically into
the module.
The module aeration device is for the most part integrated
into the module. Other module constructions are in dif-
ferent testing stages.
permeate
module aeration
A) Plate module
flat membrane onsupporting plate
module aeration
flexible hollow-fibremembrane
lower fittingwith resin
upper fittingwith resin
(depends onprovider)
permeate permeatelateral fittingswith resin
vertically arranged horizontally arranged
B) Hollow-fibre module
Figure A-16
Schematic representation of different module constructions
Annex A
321
Membrane modules are operated discontinuously. Depen-
ding on the module construction, periodic filtration pau-
ses or backwashing with permeate are performed to mini-
mize the covering layer. Therefore, it is necessary to dis-
tinguish gross and net permeate flow (see Figure A-17).
Additional chemical cleaning is required for further re-
generation of the modules and to remove the membrane
fouling (see chapter A.6.5).
To adapt the filtration capacity to the volume of inflow,
two operating modes are possible:
• The permeate flow of all modules is changed equally.
• Certain modules are disconnected such that the remain-
ing modules work with the flow permissible for conti-
nuous operation. A constant operating time of the in-
dividual modules has to be respected. Moreover, this
operating mode ensures that sufficient recovery phases
(phases without operation) for the individual modules
are kept. As a rule, this operating mode is more energy-
efficient than the first mentioned.
pause
per
mea
te v
olu
me
time
net fl
ux
filtration
cycle
gros
s flu
x
backwashing
per
mea
te v
olu
me
time
net fl
ux
filtration
cycle
gros
s flu
x
Figure A-17
Typical operating modes of the membrane modules
AnnexA
322
Capacity of the membrane bioreactor process
The advantages of the membrane bioreactor process result
from the possible higher MLSS contents in the activated
sludge tank and complete separation of all solid matter
by the membranes. From this results an improved elimi-
nation of nutrients and micro-organisms. Therefore, nitro-
gen, phosphorus and carbon in the effluent of membrane
bioreactors are reduced by the fraction which in conven-
tional plants results from solid matter in the effluent.
Membrane filters are able to retain micro-organisms to
a very large extent. The permeate complies with the
hygienic requirements of the EU Directive on Bathing
Waters 76/160/EWG [COUNCIL OF EC 1976] concerning
the microbiological parameters total number of Bacteria
coli, faecal coliforms and streptococci. Studies at the Rödingen
and Markranstädt waste water treatment plants during the
first months of operation (in 2000) have shown that the
concentrations of all micro-organisms mentioned in the
EU Directive on Bathing Waters were reduced to values
close to the detection limit, independent of the weather
conditions (dry weather, storm, continuous rain). The
limit values and guide values of the EU Directive on
Bathing Waters were met in all cases. Studies at the Rödin-
gen waste water treatment plant carried out after several
years of operation (in 2002 and 2003) have shown that
the germ reduction continues to be at a high level, but
indicate that with increasing operating time, the removal
rate may possibly decrease. This aspect has to be studied
in more detail.
Even virus, the smallest pathogenic organisms which theo-
retically may pass through the membrane pores, are re-
tained by the membrane bioreactor process. The viruses
typically accumulate with particles and micro-organisms
so that they are removed from the waste water by the
elimination of larger particles. During the studies men-
tioned above, it was possible to significantly reduce the
concentrations of intestinal viruses. However, safe com-
pliance with the limit values of the EU Directive on Bathing
Waters cannot be ensured.
Prerequisite for the high removal of pathogenic micro-
organisms in the membrane bioreactor process is that no
short-circuits between treated and non-treated waste water
exist and that membranes and connections are always
secure. This requirement seems to be trivial. In practice,
however, appropriate controls are necessary.
The elimination of micro-pollutants, e. g. residues from
drugs and substances with endocrine effect, requires bio-
logical processes or adsorption on at the sludge because
the membranes used with the membrane bioreactor pro-
cess do not retain dissolved substances.
A.6.3
Instructions for planning and design
Pretreatment of the raw waste water
Sufficient pretreatment of the waste water is an essential
prerequisite for the operation of membrane bioreactors.
Especially hair and grease may accumulate and stick to
the modules and thus cause considerable operating pro-
blems. In principle, a grit and grease trap is necessary.
Coarse matter can be removed by single-stage or two-stage
devices. Screens with spacings used up to now are not
sufficient as the only measure for the removal of coarse
matter. Therefore, screens have to be combined with sieves
or with primary treatment.
Sieves should have a mesh size of ≤3 mm and should be
preferably configured with flow reversal. The mesh size
of sieves should be chosen considering the following
boundary conditions:
• of drainage system (combined or separate system,
emptying and cleaning of stormwater tanks, etc.),
• sensitivity of the membrane module construction
concerning fibrous matter,
• other pretreatment installations, especially the spacing
of the screen, if existing.
Therefore, sieve mesh sizes of ≤1 mm may be required.
If primary treatment is used in place of a sieve, special
measures are necessary to avoid the passage of floating
matter into the activated sludge stage. Experience has
shown that primary treatment realized as so-called coarse
desludging is not sufficient to effectively retain undesired
substances.
Annex A
323
To protect the membrane effectively against coarse matter,
it is strongly recommended to install redundant screens
and sieves and not to equip the mechanical treatment
stages with an emergency circuit.
Design and construction
The design data for biological treatment in a membrane
bioreactor have to be determined according to the proce-
dure for conventional waste water treatment plants laid
down in the standard A 198 [ATV-DVWK 2003]. In general,
the loads, the inflows and the waste water temperatures
have to be determined for the design load period.
The size of the activated sludge tanks can be calculated
according to the ATV-DVWK standard A 131 [ATV-DVWK
2000a]. For determination of the volumes, a higher solids
content has to be considered which in current practice is
not chosen higher than 12 g/L. Possibly existing filtration
tanks can be added to the volume VBB minus the volume
displaced by the built-in components. For the load cases
to be fully assessed, it is necessary to consider the down-
times of filtration tanks.
Compared to conventional activated sludge plants (acti-
vated sludge tank, secondary settling tank), the total
volume of membrane bioreactors is significantly smaller
which in the case of peak loads, this results in increased
peak concentrations in the effluent for hydraulic reasons.
Experience acquired up to now with the operation of test
plants and large-scale installations suggests that non-de-
graded waste water components give rise to fouling of
the membranes and thus accelerate the reduction of the
permeability. Therefore it is recommended to bring the
waste water to the membrane only after a time which is
sufficient for biodegradation of the waste water consti-
tuents. This can be realized by adequate hydraulic design
of the tank volumes (cascading, plug-flow). Short-circuit
flows of the waste water to the membrane modules have
to be avoided at any rate.
The separate installation of the membrane stage in a fil-
tration tank is normally also advantageous for cleaning
and maintenance.
To avoid that the activated sludge in separate filtration
tanks is overconcentrated, it is required to maintain a
sufficient return sludge flow from the filtration tank back
into the activated sludge tank. Depending on the system,
the maximum solid matter content at the membrane may
be up to 18 g/L. The necessary return sludge flow is cal-
culated from the solid matter content in the activated
sludge tank and in the completely mixed filtration tank.
Attention must be paid to constant mixing of the filtration
tank to avoid deposits and to ensure optimal membrane
functioning.
The waste water flowing into the waste water treatment
plant has to be filterable at any time by the available
membrane surface area. Therefore, the design basis for
the membrane surface area is the combined water flow
QM at the lowest temperature over the course of the year
because the permeate flow depends on the temperature.
In contrast to the standard A 198 [ATV-DVWK 2003],
mean daily values of the waste water temperature are
essential.
The net permeate flow of designed installations (design
flow in constant operation) as a quotient of the combined
water flow QM and the membrane surface area AM in-
stalled is between approx. 8 L/(m2 �h) and 30 L/(m2 �h)
depending on the module type. The design has to con-
sider necessary shut-downs because of chemical cleaning,
failures, module replacement, etc. During such shut-
downs, the remaining membrane surface has to be able
to filter the maximum waste water volume QM. Depen-
ding on the membrane system, it is possible to attain, for
a limited period, significantly higher permeate flows.
To manage hydraulic peaks, a buffer volume in the form
of upstream tanks, storage capacities or as variable level
in the activated sludge tank may be useful instead of
keeping membrane surface area in reserve.
AnnexA
324
Membrane material PVDF, mod. PVC,
PES, PAN or PE1)
pH resistance 2 - 11
Filter surface area per module m2 240 - max. 2,880
Net permeate flow (QM/AM) L/(m2 �h) 8 - 30
Permeability L/(m2�h�bar) 100 - 400
Maximal working pressure mbar 300 - 400
Mean working pressure mbar 20 - 200
“Footprint“ (modules in fitted state) m2/m2 70 - 165
(filter surface area per tank floor area)
Package density (modules in fitted state) m2/m3 40 - 100
(Filter surface area per module volume)
Injection depth module aeration m 1.5 - 5.5
Energy demand module aeration2) kWh/m3INFLOW 0.25 - 0.80
Energy demand permeate pump kWh/m3INFLOW 0.06 - 0.07
Reference data on membrane systems from information
of manufacturers and operating results available up to now
are compiled in Table A-6 [WEDI 2002a]. Together with
the progress of knowledge and module development,
these data are also subject to changes.
Typical cycle times are in the range of minutes. But there
are also installations with continuous filtration during
several hours.
Information on the service life (years until the membranes
have to be replaced) cannot yet be given.
Oxygen input
With membrane bioreactors, we distinguish between the
coarse-bubble aeration of the modules and the typical
fine-bubble aeration in the activated sludge tanks necessary
for the biological processes. For the design of the activa-
ted sludge tanks, it has to be considered that the �-value
to be assessed for the air input into the activated sludge
tank must be significantly lower because of the higher TS
content of the sludge.
The tendency of the reduction of the �-value as a result
of increased solids concentrations is consistent in all
studies.
Table A-6
Characteristic data of designed membrane bioreactors [WEDI 2002a]
Nominal pore size mm < 0,1 – 0,4
1) PVDF: polyvinylidene fluoride; PVC: polyvinylidene chloride; PES: polyethersulfone; PAN: polyacrylonitrile; PE: polyethylene
2) depending on the operating mode of the modules
Annex A
325
The �-value also depends on other variables. In addition
to the aeration system, other factors include the measure-
ment method (measurements with or without waste water
inflow), the salt content, the surfactant concentration, and
the specific air flow or the flow in the tank. Measurements
at the Rödingen waste water treatment plant suggest that
the characteristics of the activated sludge or substances
of biogenic origin which are retained in the process have
effects on the oxygen input in the membrane bioreactor
process (e. g. EPS).
It is recommended to use a reduced �-value of 0.5 for the
design of fine-bubble aeration systems in membrane bio-
reactor applications. This �-value is based on a typical
solids concentration of 10 – 12 g/L. If there are specific
findings about further �-value reduction at lower TS con-
centrations, a reduction should be made.
If the cross-flow aeration of the membranes is considered
in the design to cover the biological oxygen demand, the
designer has to prove this separately, taking into consid-
eration the specific situation and the load cases. According
to the arrangement of the membranes in the system, this
oxygen input can be assessed to reduce the operating costs.
For the installation of the membranes in the nitrification
tanks, KRAUSE/CORNEL [2003] quote mean energy savings
of 15 %. If the membranes are arranged in separate filtra-
tion chambers, the energy savings are lower. However,
the instructions in section A.6.3 concerning the reactor
form and the retention time behaviour have to be ob-
served in any case.
1,00
0,75
0,50
0,25
0
alp
ha
201510 25
TS in g/L
5
Beverwijk
1st work report KA-7, only pilot plants (2000)
Markranstädt/Cornel et al. (2001)Rödingen/Cornel et al. (2001)
Rödingen/Wagner, Krause (2003)
Figure A-18
Influence of the solids concentrations on the �-value for fine-bubble pressure aeration installations
AnnexA
326
Nitrogen removal
Nitrogen removal is designed according to the ATV-DVWK
standard A 131 [ATV-DVWK 2000a].
As a result of module aeration, a considerable quantity of
oxygen is entrained with the mixed liquor recycled from
the separate filtration tank or from the filtration zone, in
particular in the case of combined water flow. This has to
be considered in the design of the process.
Phosphorus removal
With the membrane bioreactor process, phosphorus elimi-
nation can take place by pre-precipitation in the primary
treatment stage or by simultaneous precipitation in the
activated sludge stage.
For pre-precipitation, all common precipitants can be used.
There is no difference compared to the conventional acti-
vated sludge process. A disadvantage of pre-precipitation
is significantly higher sludge production in the primary
treatment stage which has to be considered in the design
of the sludge treatment facilities.
In the activated sludge stage, phosphorus removal can take
place by means of simultaneous chemical precipitation
or increased biological phosphorus removal, in principle
combined with simultaneous precipitation. With the mem-
brane bioreactor process, lower total phosphorus concen-
trations in the effluent can be attained than with a con-
ventional activated sludge process because
• the particulate phosphorus compounds can be
separated completely, and
• orthophosphate cannot be redissolved in a secondary
settling tank.
The cleaning agents used for membrane cleaning have to
be adapted according to the use of precipitants. Up to now,
no signs of increased cleaning expenditure for the mem-
branes by the use of precipitants have been observed. A
spatial distance between the dosing point and the mem-
brane modules is recommended. Additives into the waste
water treatment plants, including precipitants, generally
have to be approved by the membrane manufacturers.
Up to now, increased biological phosphorus removal in the
membrane bioreactor process has been only used within
the scope of research and development [GNIRß 2003],
[DICHTL ET AL. 2004].
Excess sludge production
The design of a membrane bioreactor typically considers
a sludge age in the range that for of simultaneous aerobic
sludge stabilization. Therefore, in principle it must be as-
sumed that the biological metabolic rates in membrane
bioreactors do not differ significantly from those in con-
ventional activated sludge plants [among others ROSEN-
WINKEL/WAGNER 2000]. Concerning the treatment of
municipal waste water, no significant reduction of the
excess sludge production can be expected compared to
conventional systems.
According to GÜNDER [1999], the excess sludge produc-
tion can be reduced by operating with an extremely high
sludge age. However, the BOD5 sludge loadings of less
than 0.01 kg/(kg d) required to achieve this are, as a rule,
are not economic.
The excess sludge production can be determined follow-
ing the ATV-DVWK standard A 131 and the ASM models
[HENZE ET AL. 1987; HENZE ET AL. 1999; GUJER ET AL.
1999].
A.6.4
Sludge treatment
General facts
The excess sludge from the large-scale membrane bio-
reactors at Rödingen, Markranstädt and Monheim are
stored in a stacking container. They are either transported
periodically to a collecting place at a central waste water
treatment plant for joint treatment with sludge from
conventional plants or they are still used for agricultural
purposes. Therefore, in Germany there is up to now no
experience with the operation of large-scale sludge treat-
ment plants.
Annex A
327
The sludge from the large-scale plants, particularly from
the Rödingen waste water treatment plant, have been sub-
ject to extensive studies which are described in the follow-
ing section.
Dewaterability
As a rule, sludge from membrane bioreactors has a small
floc size (about 50 µm, in part only 10 µm). Despite the
increased specific floc surface area of the small flocs, no
deterioration of the dewaterability has been observed.
Table A-7 shows characteristic values of large-scale studies.
In a large-scale test with a high-performance centrifuge, a
dried solid content of nearly 30 % was attained with the
sludge from the Rödingen waste water treatment plant.
Laboratory tests proved this dewaterability with results of
27 % on annual average and maximum values up to 31 %
at an organic content of the sludge (ignition loss) of
61 – 48 %. With lower organic content, the sludge showed
an improved dewaterability. The polymer demand of
2.9 gWS/kg dried solid content on average was signifi-
cantly below the polymer demand of 5.9 gWS/kg dried
solid content from 15 different conventional activated
sludge plants with aerobic stabilization.
The studies to-date show that the demand for flocculation
agents is comparable to that of conventional plants or even
lower.
The experience acquired up to now indicates that no
additional expenditure for sludge dewatering compared
to conventional sludge has to be expected. Screening in
mechanical pretreatment removes structural substances
that may affect the dewaterability.
A special solution was chosen for the waste water treat-
ment plant on the Säntigs peak (Switzerland) [MÖRGELI
2001]. The excess sludge is filled into special bags. The
water drains off and the sludge compacts. Then the sludge
is ready for dispatch by the cableway. By means of this
method, a dried solid content of approx. 20 % is attained.
This system has also been installed also at the Schwägalp
waste water treatment plant.
Digestibility
Despite the typically low sludge loading rate, which is
similar to or less than that of a simultaneous aerobic sta-
bilization plant, the organic total solids content of the
excess sludge from large-scale installations and from pilot
plants varies between 46 % and 69 %. This high organic
content was the reason for an examination of the digesti-
bility or the residual gas potential respectively according
to DIN 38 414 S8 [N. N. 1999].
Another reason to examine the digestibility is that the
membrane bioreactor process is also a possible variation
for the upgrading of existing plants with aerobic sludge
stabilization.
In literature, 200 to 300 standard litres of gas produced
per kg of organic dry solids (Nl/kg oTS) are given for the
digestion of excess sludge [BAHRS ETAL. 1994]. During the
Device/method Installation Dried solid content of the excess sludge Dried solid content after dewatering
Ignition loss of the excess sludge
Table A-7
Studies on the dewaterability of excess sludge on a large-scale centrifuge
centrifuge Markranstädt 2.4 % dried solid content
65 % ignition loss 24.5 %
Rödingen 3.8 % dried solid content
46 % ignition loss 29.9 %
Monheim 1.0 % dried solid content
54 % ignition loss 28 %
AnnexA
328
study, the excess sludge from membrane bioreactors
attained this value reported in literature.
The results show that the sludge from membrane bioreac-
tors has a (residual) gas production comparable to sludge
from conventional plants.
A.6.5
Chemical cleaning of the membrane modules
To maintain and increase the permeability and to disinfect
the permeate tubes, chemical cleaning of the membranes
is required from time to time. There is no uniform recom-
mendation for cleaning. Optimization takes place conti-
nuously based on experiences from large-scale operation.
Oxidizing chemicals serve to remove organic deposits. To
avoid AOX formation, chlorine-free chemicals should be
used, if possible, e. g. hydrogen dioxide. However, the
best cleaning results up to now have been attained with
sodium hypochlorite solution as oxidizing agent, inde-
pendent of the membrane.
Depending on the requirement and particularly to remove
inorganic deposits, more cleaning steps are added. The
following chemicals can be used: citric acid, organic per-
oxide compounds, oxalic acid, acetic acid, mineral acids,
surfactants, detergents and manufacturer-specific combi-
nation products.
As a rule, two-step cleaning by means of an oxidizing agent
and an organic acid is used.
The load on membranes from cleaning should be as low
as possible. This has to be considered in the choice and
dosage of the cleaning chemicals. The cleaning method
has to be approved by the manufacturer.
At present, the following cleaning processes are used:
• in-situ cleaning (in fitted state)
– in the activated sludge
During chemical cleaning, the membrane modules
remain immersed in the activated sludge. The chemi-
cals are added from the permeate side. The quantity
of the cleaning solution passing into the activated
sludge depends to a high degree on the concept of
the cleaning process.
– in the cleaning solution
The activated sludge is pumped off from the tank.
The tank is then filled with cleaning chemicals until
the modules are submerged.
– in the air
As a rule, the level of the activated sludge is lowered
to the bottom edge of the modules. The membrane
modules suspend freely in the air. The chemicals are
added from the permeate side. The contact time is
5 – 10 minutes.
• external cleaning
The membrane modules are withdrawn from the
membrane bioreactor tank and put into an external
“cleaning cell“.
In-situ cleaning in a cleaning solution or in the air are
particularly suited for installations with separate filtra-
tion tanks.
Up to now, we distinguish between intensive cleaning
and intermediate cleaning, depending on the chemical
concentration and the cleaning interval.
As a rule, intensive cleaning is required at least once a year
to significantly increase the permeability. It can be real-
ized, for example, with high concentrations of oxidizing
agents (e. g. NaOCl – 1,000 mg/l Cl or H2O2 – 2,000 mg/l),
followed by acid cleaning (e. g. by citric acid). The clean-
ing cycles should preferably be timed in such a way that
the maximum hydraulic performance is reached in the
beginning of the cold season.
Intermediate cleaning, typically by means of low oxidant
concentration (e. g. NaOCl – 150 mg/L Cl), serves to pro-
long the interval between intensive cleaning events. It is
carried out in intervals of 2 – 7 days. In order to realize
longterm successful intermediate cleaning, it is necessary
to apply this cleaning method during the first operating
period with a relatively contaminant-free membrane.
Annex A
329
Intermediate cleaning is not used for all module construc-
tion types.
In-situ cleaning can be used for intensive cleaning or inter-
mediate cleaning. External cleaning is used exclusively for
intensive cleaning.
The operational expenditure of external cleaning is very
high. Therefore, it has been replaced in some installations
by the in-situ cleaning method described above.
If cleaning takes place directly in the cleaning solution,
the effect at the membrane surface is far better because
the solution is not diluted by the activated sludge. More-
over, it is possible to increase the temperature of the clean-
ing water to 30 – 35 °C. To improve the mixing of the
chemicals applied in the cleaning tank, the membrane is
aerated during cleaning.
The operator of a membrane bioreactor process should
demand a detailed instruction for proper membrane clean-
ing and the necessary cleaning intervals from the plant
manufacturer or the membrane manufacturer, respectively.
In the planning of membrane bioreactors, adequate stock-
rooms, dosing devices, adequate materials for tanks and
tubes as well as safety have to be considered (Wedi, 2002b).
Since cleaning processes are being continuously developed
and may be optimized for an individual case, as many
options as possible should be kept open for the chemical
stock-room and the dosing devices in compliance with the
relevant safety requirements. In Germany, besides the in-
structions according to the Federal Water Act, also aspects
of work safety, fire protection and emission control have
to be observed depending on the combination of chemi-
cals. The following instructions can or have to be applied
in particular:
• Technical Regulations for Hazardous Substances
(TRGS), in particular TRGS 515,
• instructions and advisory leaflets of the Statutory
Accident Insurance Institutions,
• Ordinance on the Workplace (ArbStättV),
• plant identifications according to the Ordinance on
Hazardous Substances (GSV),
• if necessary, Ordinance on Flammable Liquids (VbF),
• if necessary, VCI concept for joint storage of chemicals,
predefinition of the dangerous groups for storage,
• if necessary, Ordinance on the Retention of Fire-
fighting Water (LöRüRL),
• if necessary, leak detection according to DVGW,
• if necessary, other ordinances specific to the individual
federal state.
Planning and approval of the installations should be car-
ried out in coordination with authorities and specialized
institutions such as industrial inspection boards, TÜV or
occupational health services.
A.6.6
Energy demand
The operating cost of a membrane bioreactor system is
influenced significantly by the energy demand for cross-
flow aeration in addition to the energy demand for oxy-
gen input for biological waste water treatment.
The aeration energy depends on the specific aeration de-
mand of the membrane used and the immersion depth
of the corresponding aeration devices. For the membrane
modules currently applied, these values vary in a wide
range for the specific air demand from 0.2 Nm3/(m2 �h)
to 0.45 Nm3/(m2 �h) and immersion depths of 2 metres
to 5 metres.
Current experience with large-scale operation shows a
specific energy demand for cross-flow aeration of approx.
0,25 kWh/m3INFLOW to 0.8 kWh/m3
INFLOW (mean annual
value).
Thus, the potential energy savings are to be found main-
ly in the reduction of the specific air demand and in the
increase of the filtration capacity of the membrane system
(e. g. connection or disconnection of individual modules
depending on the inflow).
AnnexA
330
If the permeate is withdrawn by pumps, a specific energy
demand of 50 W/m3 to 70 W/m3 can be assumed. Depend-
ing on the system configuration, recirculation of the
concentrated activated sludge from separate filtration
chambers has to be considered with approx. 15 W/m3 to
20 W/m3. As a result of the lower �-value, also the energy
consumption for fine-bubble aeration devices increases
by the factor �konv./�Membran.
Concrete data on the energy demand and its distribution
exists for the membrane bioreactors at Markranstädt and
Monheim. Both installations are equipped with hollow-
fibre membranes. From the figures below it can be seen
that as the waste water throughput approaches maxi-
mum capacity, the specific energy demand decreases.
The specific energy demand normalized to the mean
inflow (approx. 43 % or 35 % of Qmax) is in the range of
0.8 kWh/m3 to 0.9 kWh/m3 for both installations. Com-
pared to conventional activated sludge plants with an
average specific energy consumption of 0.3 kWh/m3 to
0.5 kWh/m3 and additional expansions for e. g. space
filtration and radiation plants with approx. 0.15 kWh/m3
to 0.25 kWh/m3 altogether, the energy demand of mem-
brane bioreactors is still high. For this comparison it has
to be taken into account that the capacity of the mem-
brane bioreactor is greater, in particular concerning the
hygiene-relevant parameters.
2.0
1.5
1.0
0.5
spec
ific
en
erg
y co
nsu
mp
tio
n [
kWh
/m3 ]
0
inflow [m3/d]
5,0001,000 2,000 3,000 4,000
microfiltration 500 Awithout air-cycling(Jun – Jul 2001)
microfiltration 500 Awithout air-cycling(Jan – Nov 2002)
microfiltration 500 Cwith air-cycling(Jan – Jun 2003)
Figure A-19
Specific energy consumption of the Markranstädt WWTP [STEIN, KERKLIES 2003]
Annex A
331
A.6.7
Upgrading of existing municipal waste water
treatment plants
In future, the main focus of necessary investments in
waste water treatment will move from new constructions
of waste water treatment plants to rehabilitation and up-
grading measures combined with expansion projects. For
these tasks, too, the membrane bioreactor process may be
a technically and financially viable solution [SCHIER 2003].
Favourable conditions for MBR treatment arise when in
the course of plant upgrades large new tank volumes would
have to be built, where problems exist as a result of in-
sufficient capacity of the secondary settling tanks, but
especially in those cases where both problems have to be
addressed. Prerequisite is that the structural condition of
the existing activated sludge tanks and secondary settling
tanks allows further utilization.
For the conversion of phase separation from settling to
membrane filtration, the utilization of the existing secon-
dary settling tank volume as additional activated sludge
tank volume is possible. In this way it is not only unne-
cessary to build new activated sludge tanks but a TSBB
concentration results which is below the TSBB concentra-
tion typical with membrane bioreactor processes. De-
pending on the degree of undercapacity of the existing
plant, the guarantee of the aerobic sludge age has to be
considered in the design of the TSBB concentration be-
sides the available activation volume. TSBB concentrations
of 4 g/l – 7 g/l usually result [FRECHEN, SCHIER, WETT
2001 and 2003]. If it were possible to realize such a con-
cept, the usual disadvantages of membrane bioreactors
(sensitivity to peak loads, unfavourable �-value) could be
largely compensated.
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
spec
ific
po
wer
co
nsu
mp
tio
n [
kWh
/m3 ]
inflow [m3/d]
500 1,000 1,500 2,000 2,500 3,000 3,500 4,000
future median of the inflow, 35 % of Qmax
start-up, non-optimized operation in July/August 2003
min. consumption filtration
Figure A-20
Specific energy consumption of the KA Monheim WWTP [WEDI 2003]
AnnexA
332
Besides the higher effluent quality of the permeate, more
process- and expansionspecific advantages of this upgrad-
ing concept have to mentioned:
• significant biological reserve capacities in the case of
future demand for expansion,
• economical handling of space resources.
Up to now this upgrading concept has not yet been im-
plemented on an industrial scale. In a first research pro-
ject, different membrane systems have been examined for
operating and design parameters by semi-technical tests
[UNI KASSEL 2004]. Besides the general technical feasibility
and technical suitability of the membrane bioreactor pro-
cess for upgrading of the waste water treatment plants
studied, it was stated that concerning the hydraulic capa-
city, the hollow-fibre systems studied attained flow rates
which were in the range of or even slightly above the
operating or design flow rates of large-scale plants. Thus we
cannot start from a reduced hydraulic capacity for the
operation of a membrane bioreactor with process-specific
low TSBB concentrations. If a higher capacity is desired, it
is recommended to carry out preliminary tests. The studies
concerning this are still ongoing (Kassel University).
A further process solution is to upgrade existing plants
with partial flow treatment with the membrane bioreac-
tor process.
A.6.8
Instructions for start-up
Principles
For the start-up of a membrane bioreactor, the principles
concerning the biological characteristics and the treatment
capacities are similar to those of conventional plants. In
the following section some specific aspects of the start-up
of a membrane bioreactor are discussed.
Performance test
Membrane bioreactors are complex technical installations,
for which functional capability and the concurrence of
the individual components are particularly important in
order to ensure long-term processstable operation.
Extensive performance tests of the individual components
and the complete process- and electric measurement and
control equipment are indispensable. The programs used
for the control of the membrane installation are sized to
the specific system of the respective project.
The functional capability of the membrane-specific pro-
cess components such as mechanical pretreatment stage
and chemical treatment is of special importance.
Leak detection
To detect defects of the membranes and their installations
due to their production or which may result from the con-
struction of the plant, it is necessary to carry out a per-
formance test to examine for leaks. The following measu-
res are possible for this purpose:
• air pressure holding test on the filtrate side
(low pressure) with an empty tank,
• air pressure holding test on the filtrate side (over-
pressure) with constant clean water level or with a
clean water level which rises during measurement.
The pressure applied for the leak test has to be adjusted
to the respective membrane system (capacity for back-
washing, e. g. with plate modules).
Start-up operation
After successful performance and leak testing, the instal-
lation is filled with activated sludge. If no adapted sludge
from a municipal membrane bioreactor is available, it is
possible to use return sludge from a conventional plant.
It is necessary to remove fibrous material from this acti-
vated sludge (e. g. by sieving).
During start-up of the installation, the TS content increases
to the level of the design values (cf. chapter A.6.3). From
this may result a change in the floc structure. At TS con-
tents of approx. 8 g/l – 10 g/l, strong foaming may occur
which can be treated for example by defoamers. When
this process is finished, the tendency for foaming decreases.
Experience has shown that the development of a foam
layer in the range of < 10 cm can be expected.
Annex A
333
A.6.9
Costs
General facts
Cost comparisons have to consider the annual costs re-
sulting from operation and capital costs. In general, cost
estimates and comparisons for a rather new process tech-
nology have the disadvantage that they typically become
inaccurate after a short time, because developments in
process optimization and free-market regularities influence
the costs to such an extent that new processes increasingly
gain competitiveness. Such estimates and comparative
calculations indicate that membrane technology may
become economically interesting, depending on the respec-
tive boundary conditions [RAUTENBACH ET AL. 2000].
For purposes of evaluating the costs of membrane biore-
actors, the increased capacity for germ reduction of waste
water compared to “conventional” processes must be
considered. For this reason, too, a simple comparison of
membrane bioreactors with activated sludge plants accord-
ing to ATV-DVWK-A 131 without germ reduction is use-
ful only to a limited extent and should be left to special
cases. As a rule, membrane installations are at present
still more expensive compared to conventional activated
sludge plants.
Since membrane bioreactors only consist of a few struc-
tures, they are advantageous under special boundary con-
ditions, e. g. sites with restricted space, complicated sub-
soil conditions or in the case of special architectural de-
mands. This is increased in particular for demands on
germ reduction in waste water due to special conditions
of the receiving water.
On account of the higher total solids content in the acti-
vated sludge, it is useful to examine for the membrane bio-
reactor process the possibility of simultaneous aerobic
sludge stabilization. From this result significant liberties
in planning. The size of the activated sludge tanks is con-
siderably reduced, settling devices and possibly necessary
filtration units can be spared as well as downstream germ
reduction installations. Depending on the possibility, sepa-
rate sludge stabilization processes and primary treatment
may be dropped.
However, the effects of increased pollution loads flowing
into the activated sludge stage and of possibly no diges-
ter gas production have to be considered in the overall
energy balance.
Investments
Additional expenses arise from the purchase of the mem-
brane installation, including the necessary mechanical
pretreatment (cf. chapter A.6.3), which has to be equip-
ped very carefully, high-performance aeration equipment,
the chemical storage room and the dosing stations as
well as the electrical and control technology.
In the case of a new construction, the additional invest-
ments for a single-stage sieving or screening installation
are limited in spite of significantly increased requirements
concerning screenings removal, redundancy and process
stability. They are in the range of 2 – 4 % related to the
construction costs of a new membrane bioreactor. A two-
stage screening/sieving installation including the enclosed
volume results in additional construction costs.
Compared to a conventional plant, smaller activated sludge
tank volume has to be kept in reserve. The reduced costs
are not as high as the pure volume comparison would
lead one to believe, especially if filtration tanks are built.
Figure A-21 shows a distribution of the investments in
the case of a new construction of a membrane bioreactor
(Monheim WWTP) for a maximum flow of approx.
300 m3/h. Concerning the mechanical equipment, the
membrane installation is clearly dominant with approx.
34 %. The expenditure for sieving installations and acti-
vated sludge tanks are of less importance.
The orienting guide values represented in Figure A-22
take into account costs for plate and hollow-fibre module
systems available on the market in Germany from 1999
to 2002, which were designed for comparable flows for
“typical“ conditions (municipal waste water, temperatures
of 8 – 12 °C) of approx. 22 L/(m2 �h) to 30 L/(m2 �h)
[WEDI 2003].
AnnexA
334
If the costs of the ready-for-use membrane installation
are normalized by the maximum inflow of the installa-
tion, the inflow-specific system price of the membrane
installation only results. This normalized cost allows mem-
brane systems with different specific filtration capacities
to be compared.
In these specifications, the ready-for-use filtration unit
with pumps, blowers, connecting tubes, dosing installa-
tions for chemicals and the necessary controls are con-
sidered. Costs for equipment engineering, start-up and,
as a rule, a five-year guarantee on the membranes are
also included. With increasing size of the installation, the
relative fraction of these services decreases significantly.
Structural parts of a waste water treatment plant or equip-
ment for mechanical pretreatment are not included.
construction engineering39 %
all data related to the total building costs
mechanical equipment44 %
electric equipment13 %
ventilation/sanitation3 %
others1 %
(filtration chamber: 4 %)(activated sludge tank: 5 %)
(total membrane filtration installation incl. electric,measure and control equipment: 34 %)
(2 compact installations sieving/grit chamber: 5 %)
Figure A-21
Example for the distribution of construction costs of a membrane bioreactor
for approximately 300 m3/h [WEDI 2003]
Annex A
335
The share for the membranes only is approx. 50% to 65%
and rises with increasing size of the installation or with
increasing maximum inflow. Currently the surface-speci-
fic prices for membranes used for large-scale applications
in Germany vary between 60 euro/m2 and 100 euro/m2
(initial investment). But membranes with lower specific
filtration capacities and correspondingly lower prices are
available on the market.
The investments resulting from Figure A-21 and those
for mechanical pretreatment have to be considered
against the savings for plant components which may no
longer be necessary, such as secondary settling tanks,
sand filtration, UV disinfection, possibly primary settling
or separate sludge stabilization facilities as well as the
site-specific cost advantages. Since the tank construction
costs are low at the moment, there are limited possibili-
ties for cost savings concerning the activated sludge
tanks, in particular in the case of systems with filtration
tanks. The additional expenses for special installations,
coatings or additional mechanical equipment are often
comparable with the cost for larger activated sludge tanks.
Due to the worldwide demand for membrane installa-
tions, additional reduction in the specific costs is expect-
ed during the next years. Also, technical simplifications
are expected in the field of mechanical equipment.
spec
ific
co
sts
[o/(
m3 /
h)]
design inflow [m3/h]
300 600 900 1,200 1,500 1,800 2,100 2,400
as of 1999 –200210,000
9,000
8,000
7,000
6,000
5,000
4,000
3,000
2,000
1,000
0
Figure A-22
Orienting net cost guide values for the ready-for-use membrane filtration installation without structural
part [WEDI 2003]
AnnexA
336
A.6.10
Annual costs
A.6.10.1
Loan servicing and membrane replacement
In principle, the cost structure for a waste water treatment
plant changes if a membrane bioreactor process is instal-
led. While with new conventional activated sludge plants
the structural equipment clearly dominates the machinery
in terms of investment cost (in a ratio of 2:1 approxima-
tely), this ratio at least reverses for membrane bioreactors,
due to the elimination of the secondary settling tank and
the smaller activated sludge tank as well as the increased
expense for machinery. This ratio may move further still
if it is not a matter of a new plant building, but of a plant
upgrading for which existing tank volumes are used (see
chapter A.6.7).
The investments for the membrane stage have to be
divided into those parts which are subject to the usual
depreciation periods for machinery, and the membrane
itself which is replaced after the end of its service life.
The membrane replacement costs have to be covered by
the loan service. For definition of a depreciation period,
the service life of the membrane has to be estimated, which
is normally shorter than the depreciation period of the
machinery.
Table A-8 underlines the influence of the membrane replace-
ment on the annual costs of membrane bioreactors. From
this, it is clear that internal measures aiming at extending
the service life of the membranes are of importance.
A.6.10.2
Operating costs
Compared to conventional activated sludge plants, mem-
brane bioreactors have higher operating costs due to the
energy- and chemical demand. An essential cost factor is
the energy demand for cross-flow aeration.
The demand for chemicals of the various membrane sys-
tems may differ significantly. Depending on the necessary
intervals of intermediate and main cleanings as well as
the chemicals to be applied, specific costs of approx.
0.2 euro/(m2 � a) to 1.1 euro/(m2 � a) have been deter-
mined. This wide range indicates that there is still need
for optimization in membrane cleaning.
A.6.11
Final remark
A comparison of cost-effectiveness has to be made exclu-
sively on the basis of the annual costs (sum of loan service
and operation costs). A comparison based only on the in-
vestment is not serious.
Costs [Ct/m3] Field1)
Table A-8
Membrane-specific annual cost shares
Cross-flow aeration 0.20 – 0.75 kWh/m3 2.0 – 7.5 B
Permeate/recirculation 0.08 – 0.10 kWh/m3 0.8 – 1.0 B
Additional demand for aeration 0.08 – 0.10 kWh/m3 0.8 – 1.0 B
Chemicals 0.20 – 1.10 euro/m2 a 0.3 – 1.8 B
Membrane replacement 10 – 5 a 13.3 – 26.6 K
1) B = operating costs; K = loan service
electric current: 10 Ct/kWh; waste water production 90 m3/(PE �a), specific membrane surface area: 1.5 m2/PE,
current chemical costs for H2O2, acids and alkalis, membrane costs: 80 euro/m2
Annex A
337
A.6.12
Advantages and risks of the membrane bioreactor
process
A.6.12.1
General facts
From the comments above it is clear that the membrane
bioreactor process has important advantages compared to
the conventional activated sludge process. However, this
process also has several risks and disadvantages. For the
individual case, an assessment of advantages and dis-
advantages has to be carried out in order to make a con-
scientious decision on the optimum process. Therefore,
the most important arguments are given again in the
following section.
Advantages
The special advantages of the membrane bioreactor process
can be summarized as follows:
• less space required because the higher TS content
allows smaller activated sludge tank volumes and
secondary settling can be eliminated,
• it is easier to enclose the waste water treatment plant,
thus higher acceptance in densely populated areas,
• the process produces hygienically perfect effluent
quality because no filterable solids are found in the
effluent, and therefore the number of germs is signifi-
cantly reduced,
• improvement in the operational reliability by avoidance
of negative effects on the effluent quality by bulking or
floating sludge or sludge carry-over,
• reduction in the residual organic pollution.
Risks and disadvantages
For each case, the risks and disadvantages that may be
relevant for the installation of a membrane bioreactor
must be assessed. In the following section, critical issues
that should be examined, depending on the existing bound-
ary conditions, are summarized:
• increased sensitivity to peak loads as a result of
reduced tank volumes,
• increased total energy demand, in particular for
module aeration,
• membrane modules may silt up or clog in the filtra-
tion zone by fibrous material, too high biomass con-
centration or poor intermixing; for this reason correct
functioning of the module aeration is critical,
• membrane damaging waste water constituents, which
may get into the waste water treatment plant e. g. as a
result of failures, may lead to considerable and irrever-
sible reduction of the filtration capacity,
• increased technical expense and additional demands
on the process control,
• input/production of pollutants by cleaning chemicals
(e. g. AOX by chlorine-containing oxidizing agents),
• building of adequate chemical stock-rooms.
A.6.13
Glossary
The terms which are of special importance for the mem-
brane bioreactor process are briefly defined in the follow-
ing section.
AnnexA
338
Backwashing
Short-term reversal of the flow direction through the mem-
brane in intervals to remove the “particles“ accumulated
during the filtration process (covering layer), usually with
permeate.
Biofouling
Development of a biofilm on the membrane surface or in
the membrane due to the growth of micro-organisms; bio-
fouling causes a reduction of the performance or the per-
meability (see also fouling and scaling).
Concentrate
Partial flow of the material mixture in which the activated
sludge retained by the membrane is concentrated. It is
usually recycled as return sludge into the activated sludge
tank (see Figure A-15).
Covering layer
Accumulation of the components retained by the mem-
brane surface.
Cross flow
The term cross flow comes from the configuration of the
dry-arranged membrane systems operated in a pressure
vessel. During this process, the membranes are overflown
(transverse flow = cross-flow) in order to limit the devel-
opment of a covering layer on the membrane surface. In
membrane bioreactors with submerged membrane filtra-
tion, a transverse flow develops at the membrane surface
by the air injected (usually coarse bubbles), which is also
called cross flow and serves to control the covering layer.
As a result of the two-phase flow, the effective mechanisms
clearly differ from the principle of classical cross-flow
operation of pressure tube systems with inside flow.
Cycle
Temporal sum of filtration phase and following back-
washing phase or shut-down phase (see Figure A-17)
Filtrate
Part of the material mixture which passes the membrane
in micro- and ultrafiltration (see also permeate).
Flow
Volume per time unit
Flux (or permeate flux)
specific filtrate volume flow per unit surface area- and
time unit (per m2 of membrane surface area, per hour),
unit [L/(m2�h)]
with: VF = permeate flux (L/(m2�h)
QF = permeate volume flow (L/h)
AM = membrane surface area (m2)
With stationary conditions, the permeate flux is calculated
from the permeate volume flow (QF) related to the mem-
brane surface area (AM). With variable conditions, only
a mean permeate flux can be given. It is determined by
choosing a sufficient time interval (∆ t) and the accompa-
nying permeate volume (∆VF).
Fouling
In general: deposition of material on the membrane, at
or in the pores. According to the material which causes
fouling, we distinguish organic fouling, inorganic fouling
and biofouling. Fouling always results in a reduction of
the performance or the permeability of the membrane
(see also biofouling and scaling).
Gross permeate flux
Current permeate flux during the filtration phase of a
cycle (see Figure A-17 and net permeate flux).
Membrane
Barrier which causes the retention of particles in mem-
brane bioreactors.
�F =QF
AM
=1
AM
�∆VF
∆ t
L
m2 � h[ ]
Annex A
339
Membrane surface area AM
The membrane surface available for the filtration process:
systems with internal flow: inner surface, for tube-
shaped systems defined by the inner diameter
systems with external flow: external surface, for tube-
shaped systems defined by the external diameter
Module
Plant component ready for connection and operation,
consisting of
• membranes or membrane elements,
• internal piping,
• module aeration,
• fittings and valves, joints,
• other holding devices
Net permeate flux
The specific permeate flux that is actually attainable in
continuous operation and which is achieved in one cycle
of the membrane installation [L/(m2�h]; the following
points have to be considered:
• filtration pauses,
• backwashing times, switching times and
• the permeate volume required for backwshing.
Operating pauses required for cleaning as well as permeate
volumes have to be considered in conceptual planning.
Operating pressure
The operating pressure is necessary to attain filtration.
The operating pressure consists of:
• transmembrane pressure and
• feeder losses.
The operating pressure is usually described as the pressure
difference between the suction side of the pump/control
instrument and the ambient pressure considering the
water level situation (see also transmembrane pressure).
Permeability
Parameter for the description of the hydraulic perfor-
mance of a membrane. Quotient from the gross permeate
flux and the transmembrane pressure; unit:
[L/(m2�h � bar)]. The permeability should be corrected to
a reference temperature in order to allow accurate com-
parison of values.
with: VP = gross permeate flux [L/(m2�h)]
∆pTM
= transmembrane pressure (bar)
Permeate
Part of the material mixture which passes the membrane
in nanofiltration and reverse osmosis (see also filtrate).
Lp =Vp
∆pTM
L
m2 � h � bar[ ]
Net permeate flux =L
m2 � h[ ]Permeate volume during one cycle [L] – backwashing losses [L]
time of the cycle [h] � membrane surface area [m2]
AnnexA
340
Remark: Although the membrane bioreactor process in
municipal waste water treatment is micro- or ultrafiltra-
tion, according to the membrane pore diameteres used,
the term permeate has become established – contrary to
the formal definition – in practice, in literature and in
the specialist discussions. This will not be changed in this
2nd work report.
Pore diameter
As a rule, the pores of pore membranes are not uniform,
i. e. they show a more or less strong pore size distribution.
The pore diameter with a maximum in pore size distribu-
tion is called nominal pore diameter (unit as a rule [µm])
(according to RAUTENBACH, “Membranverfahren“,
Springer-Verlag). The maximum pore diameter can be
determined with the help of the bubble point method
according to DIN 58 355, part 2, which is used to deter-
mine what pressure is required to press the first air bub-
bles through the membrane. The maximum pore diameter
is then calculated by means of a formula.
Scaling
Accumulation of inorganic water constituents at the
membrane after precipitation (see also fouling and bio-
fouling).
Transmembrane pressure ∆pTM
Pressure difference or pressure loss by the membrane
(between outside and inside of the membrane); abbrevia-
tion: TMP (see also operating pressure)
Annex A
341
A.6.14
Literature
ATV-DVWK (2000a): Arbeitsblatt A 131, Bemessung von
einstufigen Belebungsanlagen, GFA, Hennef
ATV-DVWK (2000b): Membranbelebungsverfahren,
1. Arbeitsbericht des ATV-DVWK-Fachausschusses KA-7,
Korrespondenz Abwasser, Nr. 10
ATV-DVWK (2002): Arbeitsbericht der AG IG-5.4 :
Endokrin wirksame Substanzen in Kläranlagen – Vorkom-
men, Verbleib und Wirkung. Deutsche Vereinigung für
Wasserwirtschaft, Abwasser und Abfall e. V., Hennef,
ISBN 3-936514-18-6
ATV-DVWK (2003): Arbeitsblatt A198, Vereinheitlichung
und Herleitung von Bemessungswerten für Abwasseran-
lagen, GFA, Hennef
Bahrs, et al. (1994): Stabilisierungskennwerte für bio-
logische Stabilisierungsverfahren; Arbeitsbericht der
ATV/BDE/VKS-Arbeitsgruppe 3.1.1, Korrespondenz
Abwasser, 41. Jg., Heft 3
Böhnke, B.; Bischofsberger, W.; Seyfried, C. F.
(Herausgeber), (1993): Anaerobtechnik, Handbuch der
anaeroben Behandlung von Abwasser und Schlamm;
Springer-Verlag, Berlin und Heidelberg, 1993,
ISBN 3-540-56410-1
Churchhouse, S; Wildgoose, D. (2000): Membrane Bio-
reactors Hit the Bid Time – From Lab to Fulls Scale Appli-
cations, 3. Aachener Tagung Siedlungswasserwirtschaft
und Verfahrenstechnik, B12, ISBN 3-921955-24-6,
Aachen
Cornel, P.; Wagner, M.; Krause, S. (2001): Sauerstoffein-
trag in Membranbelebungsanlagen; 4. Aachener Tagung
Siedlungswasserwirtschaft und Verfahrenstechnik,
ISBN 3-921955-25-4, Aachen
Dichtl, N.; Kopp, J. (1999)
Entwässerungsverhalten von Klärschlämmen aus Anlagen
mit Membranfiltration, WAP, Nr. 1
Engelhardt, E., Rothe, J. (2001): Sind großtechnische
Membrankläranlagen wirtschaftlich? Erkenntnisse aus
Anlagenbetrieb und Planung, 4. Aachener Tagung Sied-
lungswasserwirtschaft und Verfahrenstechnik, Ü3,
ISBN 3-921955-25-4, Aachen
Erftverband (2001): Weitergehende Optimierung einer
Belebungsanlage mit Membranfiltration; Zwischenbericht
über das Pilotprojekt an das MUNLV
Frechen, F.-B.; Schier, W.; Wett, M. (2001): Membran-
filtration zur Ertüchtigung von Kläranlagen in Hessen;
Begleitbuch zur 4. Aachener Tagung Siedlungswasserwirt-
schaft und Verfahrenstechnik, A3, ISBN 3-921955-25-4,
Aachen
Frechen, F.-B.; Schier, W.; Wett, M. (2003): Ertüchtigung
kommunaler Kläranlagen durch den Einsatz der Mem-
branfiltration; 5. Aachener Tagung Siedlungswasserwirt-
schaft und Verfahrenstechnik, A2, ISBN 3-921955-28-9,
Aachen
Universität Kassel, Fachgebiet Siedlungswasserwirt-
schaft (2004): Membranfiltration in Hessen, Teil 1;
Schriftenreihe des Fachgebietes Siedlungswasserwirtschaft
der Universität Kassel, Band 23 (in Druck)
Gnirß, R.; Lesjean B.; Buisson H.; Adam C.; Kraume M.
(2003): Enhanced biological phosphorus removal with
postdenitrification in membrane bioreactor. Proceedings
of the Membrane Technology Conference of the AWWA
in Atlanta, 3 – 5. March, 2003.
Gnirß, R.; Lesjean B.; Buisson H.; Zühlke S.; Dünnbier U.
(2003): Kosteneffektive Abwasserreinigung mit dem
Membranbelebungsverfahren für dezentrale Standorte.
Proceedings für Wasser Berlin 2003, Veranstaltung KWB
– ”Forschung für die Zukunft“
Gujer, W.; Henze, M.; Takahashi M.; van Loosdrecht, M.
(1999): Activated sludge model No.3., IWA Scientific and
Technical Report No. 1, IWA Task Group on Mathematical
Modelling for Design and Operation of Biological Waste-
water Treatment, Water Science and Technology, Vol.39 (1),
pp 183 – 193.
AnnexA
342
Hegemann W.; Busch K.; Spengler P. und Metzger J. W.
(2002): Einfluss der Verfahrenstechnik auf die Eliminie-
rung ausgewählter Estrogene und Xenoestrogenen in
Kläranlagen – ein BMBF Verbundprojekt; GWF Wasser
Abwasser 143 Nr. 5
Henze, M.; Grady, C.P.L.; Gujer, W.; Marais, G.v.R.;
Matsuo, T. (1987): Activated sludge model No. 1,
IAWPRC Scientific and Technical Report No.1, IAWPRC
Task Group on Mathematical Modelling for Design and
Operation of Biological Wastewater Treatment
Henze, M.; Gujer, W.; Mino, T.; Matsuo, T.; Wentzel, M.C.;
Marais, G. v. R.; van Loosdrecht, M. (1999): Activated
sludge model No. 2d, Water Science and Technology,
Vol. 39 (1), pp 165 – 182
Mörgeli, B. (2001): Die Sensation ist perfekt; 4. Aachener
Tagung Siedlungswasserwirtschaft und Verfahrenstechnik,
A7, ISBN 3-921955-25-4, Aachen
N. N. (1999): Deutsche Einheitsverfahren zur Wasser-,
Abwasser- und Schlammuntersuchung; Herausgeber:
Fachgruppe Wasserchemie der Gesellschaft Deutscher
Chemiker, Normenausschuß Wasserwesen (NAW) Deut-
sches Institut für Normung e. V., 45. Lieferung 1999,
Verlag VCH, Weinheim
ÖWAV (2002): Informationen zum Membranbelebungs-
verfahren, ÖWAV-Arbeitsbehelf Nr. 30
Arbeitsbehelfe des Österreichischen Wasser- und
Abfallwirtschaftsverbands, Wien
Rat der Europäischen Gemeinschaft (1976): EG-Richt-
linie 76/160/EWG über die Qualität der Badegewässer vom
08. Dezember 1975
Rautenbach, R.; Voßenkaul, K.; Melin, T.; Ohle, P.
(2000): Perspektiven der Membrantechnik bei der Abwas-
serbehandlung; Begleitbuch zur 3. Aachener Tagung Sied-
lungswasserwirtschaft und Verfahrenstechnik, A25,
ISBN 3-921955-24-6, Aachen
Rosenwinkel, K.-H.; Wichern, M. (2002): Bemessung
von Sauerstoff- und Überschussschlammanfall für die
Membranbelebung auf Basis des ATV-DVWK-A 131
(2000); Wasserwirtschaft · Abwasser · Abfall 05/2002,
S. 640 – 647
Schier, W. (2003): Ein exemplarischer Ansatz zur Einbin-
dung neuer Bemessungswege und neuer Reinigungstech-
nologien bei der Ertüchtigung von Kläranlagen; Schrif-
tenreihe des Fachgebietes Siedlungswasserwirtschaft der
Universität Kassel, Band 22
Stein, S.; Kerklies, G. (2003): Betriebserfahrungen mit
unterschiedlichen Membrantechniken ZeeWeed® und
VRM®; 5. Aachener Tagung Siedlungswasserwirtschaft
und Verfahrenstechnik, A6, ISBN 3-921955-28-9, Aachen
Wagner, J.; Rosenwinkel, K.-H. (2001): Einfluss gelöster
Stoffe auf den Sauerstoffeintrag in Membranbelebungsan-
lagen, 4. Aachener Tagung Siedlungswasserwirtschaft und
Verfahrenstechnik, A15, ISBN 3-921955-25-4, Aachen
Wedi, D. (2002a): Pilotprojekt Abwasserentsorgung Gai-
lachtal, Technisch-wissenschaftliche Begleitung der Mem-
branfiltration Kläranlage Monheim, 3. Zwischenbericht,
Bay. Landesamt für Wasserwirtschaft, unveröffentlicht
Wedi, D. (2002b): Membrananlagen zur kommunalen
Abwasserreinigung, Verfahren, Auslegungen und Kosten,
13. Magdeburger Abwassertage, 10./11. Oktober 2002,
Verlag Mainz, ISBN 3-89653-978-7
Wedi, D. (2003): Wirtschaftlichkeit des Membranbele-
bungsverfahrens, ATV-DVWK Membrantage, 1./2. Juli
2003 in Bonn
Annex A
343
Location Capacity m3/h Raw water Start-up Manufacturer Membrane process
A.7
Large-scale membrane installations for drinking water treatment in Germany
Neckarburg 70 Karst spring 9’1998 Aqua-source UF
Hermeskeil 140 Spring and Prims dam 2’1999 X-Flow UF
Sundern 250 Sorpe dam 3’2001 X-Flow UF
Marmagen 45 Karst spring 3’2001 Zenon UF
Denkingen 15 Karst spring 6’2001 X-Flow UF
Neustadt, Saale 70 River 7’2001 X-Flow UF
Olpe, Elspetal 80 Creek/spring 8’2001 X-Flow UF
Calw, Hirsau 50 Spring 3’2001 X-Flow UF
Jachenhausen 72 Karst spring 8’2002 Inge UF
Partenstein 35 Karst spring 11’2002 Inge UF
Olef 750 Olef dam 1’2003 X-Flow UF
Regnitzlosau 27 Well 1’2003 Zenon UF
Bad Herrenalb 36 Spring 2’2003 X-Flow UF
Kandern 50 Spring 3’2003 X-Flow UF
Lauterhofen 90 Well 5’2003 X-Flow UF
Miltenberg 80 Well 6’2003 Zenon UF
Waldberg 210 Spring 6’2003 Zenon UF
Burglauer 30 Well 7’2003 Inge UF
Bad Kissingen 120 Well 11’2003 Inge UF
Heinrichsthal 13 Well 11’2003 Inge UF
Sulzbach-Lauf. 36 Spring 12’2003 X-Flow UF
Bad Ditzenbach 22 Spring 12’2003 X-Flow UF
Günterstal 60 Spring 1’2004 PALL UF
Fellen 18 Spring 1’2004 Inge UF
Gaggenau 15 Spring 4’2004 Inge UF
Bad Herrenalb 18 Spring 4’2004 X-Flow UF
Roetgen 6,000 Dam under construction X-Flow UF
AnnexA
344
Key word Explanation
A.8
Glossary
Backwashing Short-term reversal of the flow direction in intervals to remove the particles accumulated during the filtration
process (covering layer), normally with filtrate.
Brine/concentrate Partial flow of the substance mixture which is retained by the membrane.
Capacity Surface-specific permeate flow rate of a membrane under defined operating conditions.
Concentrate Partial flow of the substance mixture which is retained by the membrane, i. e. separated from the feed respectively.
Covering layer Accumulation of the components retained by the membrane at the feed side of the membrane surface area.
Cross-flow filtration/ Operating mode: the feed flows in parallel of the membrane surface area.
dynamic filtration
Dalton [D] Unit for the molecular weight.
Dead-end filtration/ Operating mode: the membrane surface area is supplied orthogonally with the feed.
static filtration
Dynamic filtration See cross-flow filtration.
End-of-pipe measures Measures for the reduction of emissions at the end of a process chain.
Feed Material mixture to be treated in the influent (raw solution in the case of liquid substance mixtures).
Feed-and-bleed structure Variation in the connection of modules:
The concentrate of the upstream module is used as feed of the downstream module.
Filtrate, permeate Part of the substance mixture that passes the membrane.
Filtration controlled Height and thickness of the covering layer can be influenced by the pressure applied and the overflow velocity so
by the covering layer that the filtering characteristics of the covering layer can be used in a calculated way.
Fir-tree structure Variation in module connection: The modules within the blocks connected in series are connected in parallel. The
concentrate volume flow is continuously concentrated from one block to the other, i. e. minimized, the permeate
yield is increased accordingly. The permeate is discharged from each block so that the volume flow to be treated is
reduced from one block to the other.
Flow (surface-specific) or flux Filtrate or permeate volume flow related to the membrane surface area. Throughput through the membrane.
Unit [L/(m2 � h)].
Flushing Short-term operation with clear water without reversal of the permeation direction.
Fouling Development of a covering layer on the membrane by organic components which leads to a reduction of
the filtration capacity.
Intermediate cleaning Chemicals such as citric acid or oxidizing chemicals (e. g. hypochlorite) are added to the backwashing or
flushing water.
Irreversible fouling Fouling which can no longer be removed by backwashing or flushing and chemical cleanings.
Membrane Selective barrier between two phases of different concentration [RAUTENBACH 1997].
Module Connectable, operable plant component consisting of membrane or membrane elements, pressure reservoir and
module-specific apparatus parts [MARQUARDT 1998].
Molecular separation size The separation size of a membrane is indicated by the so-called cut-off molecular weight. This is the specific mass
of a macromolecule which is retained by 95 % by the respective membrane.
Nominal pore diameter Pore size which occurs as maximum in the pore size distribution (of a membrane).
Nutrient removal Degradation or elimination of nitrogen and phosphorus compounds.
Parallel connection Module connection: the feed is distributed to two or more modules.
Permeability Parameter for the description of the permeability of a membrane.
Quotient of the surface-specific flow and the transmembrane pressure. Unit: [L/(m2 � h � bar].
Permeate, filtrate Part of the substance mixture that passes the membrane.
Annex A
345
Key word Explanation
Pore membranes Separation of these membranes is based on a screening effect which can be improved by the development of a
covering layer, microfiltration and ultrafiltration membranes.
Recirculation Recycling of the concentrate or part of it into the feed.
Scaling Layer on the membrane formed by inorganic precipitations (crystallization).
Selectivity Capability of a membrane to differentiate between the components of a substance mixture to be separated.
Semi-cross-flow or Combination of dead-end and cross-flow process, e. g. by dead-end filtration with discontinuous flow in parallel
semi-dead-end process tothe membrane.
Series connection, Module connection: the concentrate of one module serves as feed of the following module. The permeate of the
cascade connection individual modules is combined.
Solution-diffusion membranes Membranes which use the different solubility and diffusivity of the substance components for separation, reverse
osmosis and nanofiltration membranes.
Stage (pressure stage) Unit of a membrane installation functioning in itself, consisting of modules, pumps, valves etc.
Static filtration See dead-end filtration.
Tertiary waste water treatment Originally: treatment steps which go beyond the separation of settleable substances and carbon elimination.
Today this term often summarizes measures which go beyond nutrient removal, zusammengefasst (e. g. sand
filtration, disinfection, material separation and treatment by membrane technology).
Transmembrane Pressure difference or pressure loss across the membrane (from the feed or concentrate side to the
pressure difference permeateside).
Waste-water-free operation Closure of the circuit so that means that no waste water emissions develop. This means in the case of membrane
processes that permeate as well as concentrate can be reused.
Yield, output Ratio of permeate (filtrate) and raw water quantity fed.
AnnexA
346
Abbreviation Sense
A.9
List of abbrevations
VBB volume of the bioreactor
BOD5 biochemical oxygen demand within five days
COD chemical oxygen demand
PE population equivalent
MF microfiltration
NF nanofiltration
Ptot totality of phosphorus compounds (unit: mg/L)
Qd daily waste water inflow at dry weather
Qt maximum waste water inflow as 2 h mean value at dry weather
RO reverse osmosis
TS Trockensubstanz: der TS-Gehalt entspricht der Biomassekonzentration (Einheit: g/L)
UF ultrafiltration
WHG Wasserhaushaltsgesetz
VN volume of the nitrification tank
VDN volume of the denitrification tank
Vvario volume of the variable zone
MW combined water flow
WWTP waste water treatment plant
ISBN 3-939377-01-5
ISBN 978-3-939377-01-6