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Technische Universität Berlin
Engineering
Wastewater disposal in rural areas - An overview of options-
Prof. Dr.-Ing. M. Barjenbruch
TU Berlin, Department of Urban Water Management Gustav-Meyer-Allee 25, D - 13355 Berlin
Phone: +49 / (0) 30 / 314 72246; Fax: +49 / (0) 30 / 314 72248 e-mail: [email protected]
Technische Universität Berlin
The TU Berlin runs the Campus El Gouna
academically like a faculty in Berlin
30 International students per course
registered as students of the TU Berlin
4-semester master course German Master’s Degree
Teaching language: English
Studential fees, but scholarships
are offered
Interdisciplinary approach
Laboratories, experimental hall and lecture
rooms are designed according highest
standards
Page 2 Three Master’s degree programs at campus El Gouna
Technische Universität Berlin
Page 3 3. Master’s degree programs at campus El Gouna
Content
Technische Universität Berlin
Page 4 3. Examples of equipment at Campus El Gouna
Wastewater situation in Germany
Informations in a nutshell
Situation Wastewater
Wastewater amount 10 Billion m3/a; 115 l/(Ca·d)
Sewage fee: 2.6 €/m³; 115.6 €/(Ca·a)
Connection to the central treatment 96 %; 3,3 mio. need people
decentralized treatment
Public sewer system: Lenght: 540,723 km; 6,57 m/E;
about 1 mio.km private sewer
78,433 stormwater tanks with 658 l/Ca
9,632 central wastewater treatment plants
COD: In 548 mg/l Out 27 mg/l Nitrogen: In 51 mg/l Out 9,0 mg/l Phosphorus In 8 mg/l Out 0,72 mg/l
Characterizations of rural areas Requirements for wastewater disposal
Small, sometimes widely separated villages and districts; with
low population density, down to 20 P/ha of urban area
Large land areas, open spaces, individual farms, scattered
settlements; small percentage covered surfaces (about 20%)
Small connection ratios, possibly incomplete sewer networks;
Little existing drainage installations,
many small wastewater treatment plants
Often agricultural structure with generally little industry and
commerce
Mainly dominated by diffuse discharges into surface water
Often recreational facilities with widely fluctuating seasonal
wastewater
The main question
Decentralized or centralized connection According to ATV DVWK A 200
Decision-making process
in wastewater disposal (Stakeholder)
Decision
centrally,
semi-centralized
decentralized
Environment Citizens acceptance,
aesthetic
Manufactures
and supplies
Politics
Water
authorities
Health
care
Costs
and Fees Process engineering
Laws and
engineering
standards
Municipality
Involved actors
Free of deliverers, manufacturers and operators interests
Wastewater discharge systems Gravity Sewer
Separate System or combined System
Pressure drainage
A lot of small pumping station for all buildings
Vacuum drainage system
Collection in shafts and sucking to central vacuum station
Flat-System (Transport without solids)
Modern sanitary concepts (separation of urine and faeces
Options for wastewater discharge
and treatment
Wastewater Treatment Centralized or decentralised on-site treatment
Suspended solids (activated sludge system)
Biofilm
Main Priority: collecting and discharge the wastewater (Disease protection)!
Rainwater discharge in dependence of the pollution
Non-polluted rainwater can be percolated into the soil or drained off on the shortest way
Rain water harvesting
PK II
Todenhäger Strasse
To
de
nh
äg
er S
trasse
Centralized or decentralized Treatment Example of a small village 120 E
Central WTP
Centralized Treatment
Each house has connection to a main sewer
Wastewater-Treatment in a central plant
Discharge into rivers Irrigation
Saving potential of gravity sewers In rural area
Reduction of the nominal pipe sizes DN 150 for the usual slope 1/DN Theoretical connection of about 1,600 PE possible
Enlarging the manhole distances to about 100 to 150 (250) m TV inspection unproblematic, proven, medium cost saving potential
Laying the pipes in the land offsite the road on public (mainly) or private property
Reducing the installation depth e.g. from 1.70 m to 1.30 m Possibly individual lifting installations in the basement is required
large savings; additional costs for private lifting installations possible
Use of trench-digging machines Very high savings, proven in open space, environmentally friendly
Todenhäger Strasse
To
de
nh
äg
er S
trasse
Centralized or decentralized Treatment Example of a small village 120 E
Decentralized Treatment
Each house (site) has its own small treatment plant (on-site)
Building of groups is possible
Receiving water or re-use for all plants required Decentral WTP
Discharge into rivers Irrigation, Re-Use
On-site Treatment Small Sewage Treatment Plants SWTP
Plant for wastewater treatment of 8 m3/d or 50 PE (150 l/(PE·d) EN 1085
Septic Tank Biological Stage
(Ex: Trickling filter)
SWTP offer a relevant solution specially in rural context
Influent Effluent
Estimated about 1,85 mio. of SWTP are in operation in Germany
No rainwater must be treated!
Pressure drainage
Pressure collection pipe
Gravity pipeline
Druckrohr-
spülstation
Pressure
flush
station
Schematic diagram of vacuum drainage
FLAT - main components
Collection chamber with special connector assembly
Gravity sewer of plastic pressure pipe
typical house connection with FLAT-system
Laying beside
the roads Depth only
1,2 to 2,0 m
Low Diameter and low depth
while using settlers Use of
existing pits
Removal of sludge
depending on climate
No
pumps
required
No problem
crossing inserted
siphon
http://www.mtmdrains.co.uk/tankempty.html
Centralized wastewater treatment plant (WTP) Differentiation according the process
Natural methods:
Reed beds (vertical or horizontal flow)
Settling ponds (only mechanical effect)
unaerated wastewater lagoons
aerated wastewater lagoons
Technical wastewater treatment method
Mechanical-biological wastewater treatment plant (compact design)
Mechanical-biological wastewater treatment plant in separate design
– Activation methods (SBR plants, oxidation ditches, compact plants, membrane
bioreactors)
– Biofilm technologies (Trickling filters, Rotating disc, submerged bed, fluidized bed)
– Tow stage treatment (anaerobic (UASB) + aerobic)
Reed beds Recommended range : 4 - 50 PE [Otto 2000]
Vorklärung
Pumpenschacht
Bodenfilter
Ablauf
Reed bed (horizontal flow)
effluent gravel
effluent
Inlet
Inlet
Septic tank
Septic tank
Pump with
shaft
Reed bed (vertical flow)
Compact-System
SBR-Technology (Sequencing Batch Reactor)
Excess-
sludge
Decantation
min. level
effluent
Reaction (circulation)
max. level
Influent
Charging
Reaction (aeration)
Sedimentation
Break
SBR-Technology (Sequencing Batch Reactor)
WWTP Lalendorf
2.500 PE
aeration-phase
side view
Rotating Biological Contactor (RBC)
Definition: Primary treated wastewater is
put in contact with discs colonized with
microorganisms
Rotation of discs provides aeration
Disc material: polythene, PVC, polystyrene
< 5,000 – 10,000 PE
Low Energy demand
Stable operation easy maintenance
A secondary settler is necessary
Shaft bearings and mechanical drive units
require frequent maintenance
Phosphorus elimination only with
chemicals
Source: Naylson M. Maciel, 2009
Example of efficiency comparison
Process stability (plants up to 5,000 PE;) COD-Elimination
0
10
20
30
40
50
60
70
80
90
100
0 100 200 300 400 500
COD-Effluent [mg/l]
Sta
y-b
elo
w-p
rob
ab
ilit
y [
%]
Sequencing-Batch-Reactor
Oxidation ditch
Classical activated sludge
Compact activated sludge
Trickling filter
(Adapted from US EPA)
Cost Comparison Investment
Source: Naylson M. Maciel, 2009
* Stabilisation (Halbach 2004)
0
50
100
150
200
250
300
350
400
Artificial Lagoon Trickling Filter Rotating Biological
Contactor
Constructed
Wetlands
Activated sludge*
Inv
es
tme
nt
[€/E
]
Summary and recommendations
Decision of drainage system
Central or decentralized treatment
Criteria: length of necessary sewer (< 12…15 m/PE)
Choice of treatment system
Natural-treatment system
Technical treatment system
Criteria
–Investment cost
–Operational costs
–Space requirements
–Knowledge and education of operators
Examples of No-Mixtoilettes Ecosan-Principle
Faeces
biogas
Urine
fertilizer
Water systems - Lübeck-Flintenbreite
Oldenburg 2004
Membrane Bioreactor
Zulauf
Permeat
Überschuss-schlamm
Belebungsbecken getauchteMembran
Activated Sludge reactor Submerged
Membrane
Excess
sludge
Inflow
Advantages
high content of biomass
high purification efficiency
Desinfection
Zenon ZeeWeed
