ECO/13/630314 LESS-WATER BEV.TECH

CIP Eco-innovation First application and market replication projects Call Identifier: CIP-EIP-Eco-Innovation-2013

www.lesswaterbevtech.com

Less-Water Bev.Tech Contract ECO/13/630314

Scientific paper redaction Deliverable D.11 – WP6

Reporting Date 31/03/2016

Project coordinator: A DUE DI SQUERI DONATO & C. S.p.A.

Project website: www.lesswaterbevtech.com

DISSEMINATION LEVEL PU Public PP Restricted to other programme participants (including the Commission Services) RE Restricted to a group specified by the consortium (including the Commission Services) CO Confidential, only for members of the consortium (including the Commission Services)

CIP-EIP-Eco-Innovation-2013: Pilot and market replication projects - ID: ECO/13/630314 LESS-WATER BEV.TECH.

LESS-WATER BEV.TECH D6.11.doc - ECO/13/630314 p. 2 of 2

Description of the Deliverable n. 11 of Work Package 6 This deliverable reports about the publication of the first two scientific reports, as scheduled,

on relevant scientific journals in the field of energy, water management and production

process design and optimisation.

These activities are particularly important for the dissemination of the new technology among

the international academic community.

The project outcomes are going to be presented and discussed at two international

conferences, as follows:

# Title of Paper Authors Conference Proceedings

1

Design of an innovative plant for the wastewater recovery and purification in the food & beverage industry

Marco Bortolini Mauro Gamberi Francesco Pilati Alberto Regattieri Riccardo Accorsi (Department of Industrial Engineering, Alma Mater Studiorum - University of Bologna, Italy)

4th International Conference on Sustainable Design and Manufacturing, April 26-28 2017, Bologna, Italy http://sdm-17.kesinternational.org/index.php

Published in a scientific book edited by Springer

2

A review of technologies and applications for water purification in the food & beverage industry

Riccardo Accorsi Marco Bortolini Emilio Ferrari Francesco Pilati (Department of Industrial Engineering, Alma Mater Studiorum - University of Bologna, Italy)

Summer School F. Turco, Industrial Systems Engineering, September 13-15 2017, Palermo, Italy http://www.summerschool-aidi.it

Published on the on-line academic channels of sharing scientific memoirs (Scopus database)

The last two scientific papers are going to be published at the end of work package, by

September 2017, and will be reported under the scheduled Deliverable 12 of WP6.

adfa, p. 1, 2011. © Springer-Verlag Berlin Heidelberg 2011

Design of an innovative plant for the wastewater recovery and purification in the food & beverage industry

Marco Bortolini1, Mauro Gamberi1, Francesco Pilati1, Alberto Regattieri1 and Riccardo Accorsi1

1 Department of Industrial Engineering, Alma Mater Studiorum - University of Bologna, Italy {marco.bortolini3, mauro.gamberi, francesco.pilati3,

alberto.regattieri, riccardo.accorsi2}@unibo.it

Abstract. The food & beverage (F&B) industry is among the most water inten-sive sectors with thousands of litres per hour of raw water requirement. Starting from the statement of this issue, an overview of the evidences from the field and a quick survey of the existing technologies for the raw water saving through its local collection and treatment before discharge, this paper investigates the design of an innovative industrial plant for the water closed-loop recovery, purification and local reuse. Actually, a prototype of such a plant is working within a mid-size F&B company operating in the Emilia-Romagna region, Italy. The plant nominal capacity is of about 45,000 l/h of discharged wastewater. It integrates water ultra-filtration and reverse osmosis technologies. Details of the functional module design and of the logic of control are in the present paper. Finally, few preliminary evidences from the plant field-test are provided.

Keywords: Water Saving, Food & Beverage Industry, Water Purification, Lo-cal Closed-Loop Water Chain, Sustainable Plant Design.

1 Introduction

Water is the key of life and its availability is crucial for the equal growth of communi-ties [1]. Human activities require millions of litres of pure water per year. At a global scale, the most of the water use occurs in the agricultural sector even if high water volumes are necessary, also, in industry [2]. Focusing on the European Union (EU) area, the highest amount of water consumption is from industrial production plants. In the last decades, many investments are on water technologies. As example, every year around $150 billion are spent, worldwide, on wastewater treatment (industrial, residen-tial and agricultural fields) and this figure is set to exceed $240 billion by 2020. In particular, in the wastewater treatment, $12 billion are spent every year for equipment for wastewater treatment, with an expected annual growth of 6% by 2020 and $4.2 billion are spent on membrane systems (+12% by 2020) [3]. Moreover, toward water

saving are moving all the new regulations and laws at any level, from EU, to the na-tional, regional and local Authorities. Among all the industrial activities, Food & Beverage (F&B) is a very water intensive sector. Both foodstuff and beverage production and related auxiliary activities, e.g. plant washing, sanitation activities, steam generation, etc., require large amounts of pure water and, at the same time, generate thousands of litres of wastewater per hour. Consequently, improvements and innovations in such a sector, leading to the reduction of the required primary water, save thousands of litres of such a crucial resource con-tributing to a relevant reduction of the environmental impact of the F&B processes. Possible interventions for the conservation of the water resources belong to two major groups. The former deals with innovations to reduce the amount of the required primary water, the latter focuses on actions to recover wastewater and to treat it so that it be-comes reusable within the creation of virtuous closed-loops. The F&B sector is critic, also, because of water is subject to very high quality standards even in the case such a resource is used, simply, for the plant and machinery washing. The actual standards specify that the process water must always equals the quality of the drinkable water. Finally, the costs connected to water management in the F&B sec-tor are out of being negligible. The main drivers include outcomes for water collection and/or purchase, the investments and costs for water treatment to guarantee the ex-pected quality, the investments and costs for wastewater discharge and/or post-treat-ment and regeneration, etc. Starting from this background, this paper focuses on the wastewater recovery and local treatment presenting the design of an innovative plant for the water collection, local purification and reuse leading to a significant saving of the extracted pure raw water. This system integrates a series of functional modules targeted to separate the typical pollutants from water, e.g. suspended and dissolved solids, bacterial charge, etc. A pro-totypal system, with a nominal capacity of about 45,000 l/h of input water, is described and actually works within a mid-size F&B company operating in the Emilia-Romagna region, Italy. According to the paper goals, the reminder sections are the followings: Section 2 pre-sents the state of the art in the field of water recovery and local reuse, Section 3 details the plant structure, size and target productivity, while Section 4 describes each plant functional module. Preliminary evidences from the plant run are in Section 5 before drawing the paper conclusions in the last Section 6.

2 Background

The overall purpose to locally recover, purify and reuse process wastewater in the F&B industry is forced by the following boundaries defining the area of influence and action of the adopted technologies. Particularly, the following two elements strongly influence the effectiveness and applicability of each water treatment plant:

─ Existing regulations and restrictions on the water and wastewater collection, treat-ment and reuse within the F&B sector;

─ Available technologies for water purification, their fit with the F&B process features and parameters, e.g. water flowrate, pollutants, level of automation and maintenance, etc.

The following sub-sections provide some details about such elements focusing, mostly, on the EU and Italian contexts because of the installation area of the prototypal plant under investigation.

2.1 Reference regulations on water and wastewater use

At the EU level, high attention is paid by the EU Commission and the central commu-nitarian institutions on the quality and quantity of water to use. This is particularly true for the most water intensive sectors, as F&B. The Regulation (Ec) No. 178/2002 of the European Parliament and of the Council pro-vides the general principles and requirements of food law. It further establishes the European Food Safety Authority as the institution demanded to promote, apply and control the complex set of procedures in matters of food safety. The aim is to assure a high level of protection of the human health and to strength the consumer interest in relation to food, taking into account the diversity in the supply of food including tradi-tional products. Despite this regulation provides an ordered framework of the F&B sector at the EU level, previous EU directives set restrictions and references to the quality of drinkable water. As example, the Council Directive 98/83/EC on the quality of water intended for human consumption, known as the ‘Drinking Water Directive’, clearly states the gen-eral obligation of protecting human health from the adverse effects of any contamina-tion of water intended for human consumption by ensuring that it is wholesome and clean. It further sets quality standards to achieve and forces the member states to follow the principles of planning, regulating, monitoring, informing and reporting toward the F&B stakeholders about the quality level of water for the human consumption they use. Finally, starting from the late 2015 Eurostat data stating that up to 40% of the EU water extractions goes to industry and that a same percentage of the industry wastewater is not treated at all before discharge, the EU is forcing the member states to decrease their water footprint. This is particularly true within the F&B sector that presents an overall water footprint among the highest in industry together with textiles, papers, oil and basic metals. At the Italian level, the following laws and decrees define the milestones and roadmap toward water quality and quantity control and saving:

─ Legge 36/94 ‘Disposizioni in materia di risorse idriche’ (Legge Galli) setting the

concepts of water saving, recovery and reuse; ─ D. Lgs. 152/99 ‘Disposizioni sulla tutela delle acque dall'inquinamento’ (Testo unico

sulle acque) transfering to regions the responsibility of setting rules for water saving, control and reuse;

─ GAB/DEC/93/06 ‘Norme tecniche per il riutilizzo delle acque reflue’ prohibiting the use of recovered and purified wastewater within F&B and pharmaceutical industries

except in the case of a local recover, i.e. water collection and treatment inside the industry perimeter through local closed-loop chain;

─ D. Lgs. 31/2001 ‘Attuazione della Dir. 98/83 del Consiglio Europeo relativa alla

qualità delle acque destinate al consumo umano’ actuating the EU Council Directive 98/83/EC and regulating the water quality control and responsibilities of industry and the control Authority.

The proposed wastewater recovery plant matches the regulations in force locally recov-ering and reusing the process water through the adoption of the purification technolo-gies shortly revised in the following sub-section.

2.2 Water purification technologies

The water purification technologies aim at separating specific pollutant categories from the water flow so that the final water quality matches the standard forced by regulations and the process technical features. Within the F&B industry, the key pollutant categories belong to suspended and dis-solved solids (e.g. silica, salt ions, fungi, silt, rust, floc), microbiological contamination (e.g. bacterial colonies, pyrogenic contamination), minerals, heavy metals (e.g. lead, arsenic, cadmium, selenium, chromium) and dissolved gases. Among them, the first and second categories are strongly relevant in F&B wastewater, while the others are less critic because of initial raw water purification and very low contamination during the process. A further element to consider when screening the water purification technologies to apply to the F&B sector is the continuity of the process and the standard flowrate to manage. This sector belongs to the process industry, i.e. continuous flow of water to feed the process, with an impressive water consumption, e.g. 30,000 to 80,000 l/h of raw water need. Consequently, the wastewater purification technologies to look for have to work coherently to the main process. As example, no batch processes are fea-sible despite of having uneconomic large tanks to store the water. Similarly, the purifi-cation speed, in terms of litres of purified water per hour of work, has to fit with the range of the wastewater production. Given such boundary conditions and with reference to the target plant described in the following, the investigated purification technologies belong to the membrane group and to ultraviolet (UV) steriliser. According to Wilf (2008) and Macedonio et al. (2012) [4, 5] membranes purify water according to the so called ‘mechanical sieve theory’ even if chemical reactions and

biological pollutant degradation become possible depending on the membrane materi-als. Membrane technologies include filtration and reverse osmosis (RO). Filtration is distinguished among micro-, ultra- and nano-filtration depending on the dimensions of the membrane pores. The target pollutants removed by such technologies are the sus-pended and dissolved solids until the dimensions of 1nm. The next Table 1 proposes the evidences of a short review of recent contributions about the application of the membrane technologies within the F&B industry.

Table 1. Membrane technologies, F&B application review.

Year Authors

Membrane technology

Mic

ro-fi

ltrat

ion

[0.1

-0.5

]µm

Ultr

a-fil

tratio

n

[0.0

05-0

.05]

µm

Nan

o-fil

tratio

n

[0.0

005-

0.00

5]µm

Reve

rse

Osm

osis

Ref.

2013 Kujawski et al. [6] 2013 Sudhakaran et al. [7] 2014 Sorlini et al. [8] 2015 Alkaya and Niyazi [9] 2015 Mahmoud et al. [10] 2015 Mohammad et al.

[11] 2016 Ghimpusan et al. [12] 2016 Meneses & Flores [13]

Frequently, ultra-filtration and RO are coupled to remove the most of the suspended and dissolved solids from the water flow. Finally, because of the UV radiation inactivates the most of microorganisms, standard modular UV units are widely diffuse at highly competitive cost to tackle the water mi-crobiological contamination. The degree of inactivation depends on the UV dose and time exposure (in µW·s/cm2).

3 Plant overview and structure

The design of the plant to recover and purify wastewater starts from the analysis of the existing local water sources, the available flowrates and the level of the pollutants to remove. After that, the overall concept of the plant is figured out, sized and its integra-tion within the industrial operative environment is done. In this context, the case of a mid-size F&B company producing soft drinks, non-car-bonated beverages, juices and vegetable sauces is considered. The industrial plant is located in the Emilia-Romagna region, Italy and, actually, it supplies its water need by pumping underground pure water from five wells. The average annual consumption is of about 2.4 million m3 of water managed in an open loop, i.e. discharged after the use. The key water streams are toward the coolers of the steam heating plants, the channels feeding the production lines with fruit and vegetables and, mainly, the RO unit produc-ing the process pure water. Therefore, the stream of wastewater, in order of relevance, are from fillers (three lines per ~30,000 l/h, continuous), RO retentate (~15,000 l/h, continuous), cleaning in processes (~4,000 l/h, discontinuous), cooling towers (~2,000 l/h, continuous) and syrup room (~1,000 l/h, discontinuous). Among them, the first two streams are the most appealing in terms of quantity and continuity of the water so that the recovery and purification plant size is based on such two sources with a global flowrate of about 45,000 l/h. Pipes to connect the other streams to the input tank are

provided to increase the overall recovery rate. Concerning the input water quality, lab analyses on water samples highlight the presence of suspended and dissolved solids, e.g. conductivity 1,625 µS/cm, total suspended solids 1,280 mg/l and turbidity 134 NTU.

3.1 Plant functional structure

The following Fig. 1 proposes the overall block diagram of the plant functional struc-ture where Niagara is the nickname of the installed recovery and treatment plant. The RO unit (1) provides 15,000 l/h of retentate while the fillers (2-4) generate 6,000, 9,000 and 15,000 l/h of wastewater, respectively. Filler wastewater flows within the active carbon filter (5) removing the peracetic acid (hazardous for the membranes) before reaching the input tank (6). Such a tank collects eventual other wastewater flows (7). Units (8) and (9) are the pre-filtration and ultra-filtration modules, removing the most of the suspended solids. Their target efficiency is of about 4,000 l/h of waste per 45,000 l/h of entry water (~91%). After that, a tank (10) collects the filtered water, i.e. buffer, to decouple such a module from the RO unit (11) that removes the solutes (target effi-ciency of about 61%). Finally, the UV unit (12) reduces the microbiological charge before the water exits the system and it is collected in the output storage tank. Finally, the cleaning in place module (13) guarantees the periodic backwash of the pre-filtration, ultra-filtration and RO membranes according to the planned maintenance schedule. During cleanings, pure water flows backward through the membranes removing the collected impurities. The overall target plant efficiency is of about 25,000 l/h of recovered water starting from 45,000 l/h of input wastewater (~55.6%).

3.2 Supervising system

The supervising system allows the autonomous run of the plant managing both the up time and the periodic cleaning in place cycles. The local custom PLC acquires the sig-nals from the field, manages the plant and collects the run data to store and communi-cate via Ethernet. The sensors installed on the plant control the key parameters among flowrate, temperature, pH, redox, pressure drop and the turbidity. Finally, the quantity of the treated water and the overall efficiency are real-time updated.

4 Plant functional units

The following list is in accordance with the numbering of Fig. 1 and provides more details about the design features of the functional modules together with some pictures.

1. Recovery tank from RO retentate. Flowrate 15,000 l/h. Equipped with a collection tank, pump and level control;

2. Recovery tank from filler No.1. Flowrate 6,000 l/h. Equipped with a collection tank, pump and level control;

Fig. 1. Installed plant functional structure, block diagram.

3. Recovery tank from filler No.2. Flowrate 9,000 l/h. Equipped with a collection tank, pump and level control;

4. Recovery tank from filler No.3. Flowrate 15,000 l/h. Equipped with a collection tank, pump and level control;

5. Activated carbon filter tank to remove peracetic acid. Capacity 6.65 m3, active car-bon NCL 1240, flowrate 30,000 l/h. Flow control in input and temperature, pH, and redox control in output;

6. Raw water storage tank. Capacity 30 m3. Equipped with a pump, flowrate 45,000 l/h, and level control;

7. Other pollutant input flows. Max flowrate 2,000 l/h. Equipped with a level control; 8. Pre-filtration unit to pre-process the entry wastewater protecting the ultra-filtration

membranes. Two units of 25,000 l/h each equipped with 150 µm self-washing mem-branes. Flow control in input and pressure drop control to manage self-washings (see Fig. 2);

1 – REVERSE OSMOSIS

“CUSTOMER”

8 - PREFILTRATION

“NIAGARA”

5 – ACTIVATED CARBON

FILTER “NIAGARA”

30000 lt/h 15000 lt/h

6 – RAW WATER STORAGE TANK

“CUSTOMER”

7 - POLLUTION DOSING

“NIAGARA”

3 – FILLER PET 2

“CUSTOMER”

DRAINING

4000 lt/h

10 – ULTRAFILTERED

WATER TANK “NIAGARA”

11 - REVERSE OSMOSIS

“NIAGARA”

12 – ULTRA VIOLET

TREATMENT “NIAGARA”

30000 lt/h

45000 lt/h

41000 lt/h

STORAGE TANK “CUSTOMER”

41000 lt/h

25000 lt/h

25000 lt/h

2 – FILLER PET 1

“CUSTOMER”

4 – FILLER PET 3

“CUSTOMER”

6000 lt/h 9000 lt/h 15000 lt/h

45000 lt/h

9 - ULTRAFILTRATION

“NIAGARA”

DRAINING

16000 lt/h

13 – CLEANING IN PLACE

“NIAGARA”

Fig. 2. Pre-filtration modules.

9. Ultra-filtration unit. Parallel of eight modules. Flowrate 45,000 l/h. 75nm PVDF membranes working both cross-flow and dead-end. Flow and turbidity control in input and output and pressure drop control to manage cleaning in place (see. Fig. 3);

Fig. 3. Ultra-filtration modules and membrane section.

10. Storage tank. Capacity 8 m3. Equipped with a pump, flowrate 45,000 l/h, and level

control and used for ultra-filtration backwash; 11. RO unit. Parallel of four modules. Flowrate 41,000 l/h to remove up to 15 mg/l of

solutes. Flow and conductivity control in input and output, temperature control in input to protect the membranes and pressure drop control to manage cleaning in place;

12. UV unit. Flowrate 25,000 l/h. Reduction of the microbiological charge, wavelength 253 mm, 40 mJ/cm. Temperature and irradiation control.

13. Cleaning in place. Flowrate 25,000 l/h. Capacity 1.5 m3, dosing of acid, caustic, an-tiscalant, sodium bisulphite, clorine. Flow, temperature and conductivity control.

5 Preliminary field-test

Despite a wide field-campaign to test the plant performances under different input wastewater quantity and quality is among the future activities, the evidences of a pre-liminary field-test after the plant installation and tuning are available to benchmark the adopted technologies against a typical wastewater produced within the considered F&B industry. The field-test goal is to purify a 0.1% sugar concentration wastewater coming from the syrup room. The water flowrate is limited to 35 m3/h due to primary plant operative contingencies so that the treatment plant works at a reduced power. The test

is ~2.5 hour long and the total input wastewater is of about 90 m3. The ultra-filtration unit works in cross-flow mode. Samples of the input and output water and of the process water after the ultra-filtration unit are collected and analysed by an independent lab. At this stage, field-tests validate the filtration technology so that the microbiological charge is not measured. The overall amount of recovered and purified water is of about 67 m3 with an overall efficiency of 74.4% (this value is in absence of any output pure water use for the plant cleaning in place). The following Table 2 proposes an extract of the physical and chemical proper-ties of the entry and purified water together with a reference benchmark for EU drink-able water. The water analyses confirm the effect of the filtration units to remove a very relevant percentage of the suspended solids and solutes making the output purified wa-ter of interest for use within the F&B industrial plant, e.g. steam boilers, process uses.

Table 2. Field-test results.

Input wastewater

Output purified water

Drinkable water limits

Total Hardness (CaCo3) [mg/l] 767 <2 150÷500 Oxidability (Kubel) [mg/l O2] 3530 2.1 5 Conductivity [µS/cm] 1625 20 2500 pH 4.1 5.9 6.5÷9.5 Redox potential [mV] 201 404 - Total Suspended solids [mg/l] 1280 20 250 Turbidity [NTU] 134 0.6 <1 Total Alkalinity (CaCo3) [mg/l] 281 18.7 <85 BOD5 (O2) [mg/l] 1741 <5 5

6 Conclusions

This paper tackles the challenging issue of reducing the water footprint of the food & beverage (F&B) industry, known as a very water intensive sector, presenting the design and preliminary field-test of an innovative plant to recover and locally purify the pro-cess wastewater, decreasing the raw water use. The plant integrates an ultra-filtration, reverse osmosis (RO) and ultraviolet (UV) unit with a target overall efficiency of about 55.6%. The nominal capacity is of 45,000 l/h coherently to the wastewater flow of mid-size F&B industries, as the Italian company considered within the present industrial research. The preliminary field-test highlights results of interest for process reuse of the purified water, e.g. steam boilers, while the output water analyses highlights conditions within or close to the EU drinkable water limits. The next steps have to fully validate the proposed solution through a multi-scenario analysis of the plant performances and water quality varying the input conditions. Furthermore, the plant life cycle cost and life cycle assessment are of interest to quantify the global benefit of introducing such a system instead of open loop water practice.

Acknowledgments. This work is developed within the CIP Eco-innovation Project No. Eco/13/630314/LESS-WATER BEV.TECH, co-funded by the Eco-innovation Initiative of the European Union, in partnership with A DUE S.p.A. and CVAR Ltd.

7 References

1. United Nations (UN), (2011). The Millennium Development Goals Report 2011. Lois Jensen ed., New York, USA.

2. United Nation (UN), (2009). The World Water Assessment Programme. Retrieved from: http://webworld.unesco.org/water/wwap/wwdr/wwdr3/pdf/WWDR3_Water_in_a_Changing_World.pdf

3. RobecoSAM, (2012). )Sustainable Asset Management Retrieved from: https://issuu.com/sam-group.com/docs

4. Wilf, M. (2008). Membrane types and factors affecting membrane performance. National Wa-ter Research Institute, Fountain Valley, CA.

5. Macedonio, F., Drioli, E., Gusev, A. A., Bardow, A., Semiat, R. and Kurihara, M. (2012). Efficient technologies for worldwide clean water supply. Chemical Engineering and Pro-cessing: Process Intensification, 51, 2-17.

6. Kujawski, W., Sobolewska, A., Jarzynka, K., Güell, C., Ferrando, M. and Warczok, J. (2013). Application of osmotic membrane distillation process in red grape juice concentration. Jour-nal of Food Engineering, 116(4), 801-808.

7. Sudhakaran, S., Lattemann, S. and Amy, G. L. (2013). Appropriate drinking water treatment processes for organic micropollutants removal based on experimental and model studies—a multi-criteria analysis study. Science of the Total Environment, 442, 478-488.

8. Sorlini, S., Gialdini, F. and Collivignarelli, M. C. (2014). Survey on full-scale drinking water treatment plants for arsenic removal in Italy. Water Practice and Technology, 9(1), 42-51.

9. Alkaya, E. and Niyazi, G. (2015). Resources, Conservation and Recycling Water recycling and reuse in soft drink/beverage industry: A case study for sustainable industrial water man-agement in Turkey. Resources, Conservation & Recycling, 104, 172–180.

10. Mahmoud, K. A., Mansoor, B., Mansour, A. and Khraisheh, M. (2015). Functional graphene nanosheets: the next generation membranes for water desalination. Desalination, 356, 208-225.

11. Mohammad, A. W., Teow, Y. H., Ang, W. L., Chung, Y. T., Oatley-Radcliffe, D. L. and Hilal, N. (2015). Nanofiltration membranes review: Recent advances and future prospects. Desali-nation, 356, 226-254.

12. Ghimpusan, M., Nechifor, G., Nechifor, A. C., Dima, S. O. and Passeri, P. (2016). Case stud-ies on the physical-chemical parameters' variation during three different purification ap-proaches destined to treat wastewaters from food industry. Journal of Environmental Man-agement, in press.

13. Meneses, Y. E. and Flores, R. A. (2016). Feasibility, safety and economic implications of whey-recovered water in cleaning-in-place systems: A case study on water conservation for the dairy industry. Journal of dairy science, 99(5), 3396–3407.

A review of technologies and applications for water purification in the food & beverage industry

Riccardo Accorsi*, Marco Bortolini*, Emilio Ferrari*, Francesco Pilati*

* Department of Industrial Engineering, Alma Mater Studiorum - University of Bologna, Viale del Risorgimento 2, 40136 – Bologna, Italy

(riccardo.accorsi2@unibo.it, marco.bortolini3@unibo.it, emilio.ferrari@unibo.it, francesco.pilati3@unibo.it)

Abstract: Food & Beverage (F&B) industry is known as a water intensive sector. Thousands of litres per hour of pure water are necessary to produce the final drinks, for the line and backup process requirements of medium size production plants. Due to health restrictions and the F&B standard, the physical, chemical and biological quality of process water has to fit with high level of purity. To this purpose, all F&B plants require a dedicate water purification unit making raw water (both primary and recovered) ready-for-use. Such units are process plants based on mechanical and chemical purification technologies, mainly. This paper aims at revising the state-of-art of research and practice in this field. Starting from the process description and the expected water quality level, a matrix analysis, according to a panel of classification drivers, allows outlining the current research streams and the most popular technologies. The industrial sector, the fluid features and the adopted technology are among the investigated drivers. Results highlight a wide range of solutions, often combined in series to increase the final effect. Lacks are in applications dedicated to the wastewater purification, implementing local close-loops to decrease the overall F&B water intensity.

Keywords: Water purification, Food & Beverage, Process industry, Matrix analysis, Review.

1. Introduction

Water is the key of Earth’s life and lies behind all anthropic activities. The availability of pure water is essential for social, technological and economic progress. The FAO Aquastat database provides wide information about the origin, use and disposal of this basic resource (FAO, 2016). A scattered scenario appears. Water withdrawal ranges between <100m3/inhab/yr for Centre Africa and >800m3/inhab/yr for North America and the Western Europe. Furthermore, at global level, over 70% of the ~4 million m3/yr water withdrawal is for agricultural uses, 20% goes to industry and the remainder supplies municipal needs. Such balance is changing, progressively, due to industrialization. Starting from the developed countries, the incidence of the secondary sector on the water balance is increasing rapidly. Europe leads this transition. 2014 data states that industry water intensity is of about 57%, while agriculture is at 22% (Aquastat, 2014).

Industry is hungry of water and highly pure water. All the coded Eurostat industrial sectors require water within the production processes and/or incorporate water into the delivered final products. Multiple evidences fix ‘top six’ industrial sectors in terms of water consumption, i.e. food & beverage (F&B), textiles, paper and paper products, energy, petroleum and chemicals, basic metals, motor vehicles and transport equipment (Eurostat, 2015).

F&B industry uses pure water for washing, preparing, cooking and handling food produces, to clean the primary

packages containing food and drink with thousands of litres per hour of water need for a middle side F&B production plant. Water is pure if contaminants of any type, e.g. biological, chemical, etc., are below safety limits for the human health and the safe process assessment (Grimm et al., 1998). Raw water in input to the process has ground or underground origin and it is withdrawn, locally, by the process industry itself. Uses of the grid water are rare due to the required quantities and for economic reasons. Furthermore, wastewater at the end of the process is discharged, i.e. open loop, after post treatments to match the existing regulations about wastewater quality levels. The quality of raw water entering the F&B industry makes it not ready-to-use due to low purity. F&B production sites have local purification plants treating water before its use within the main process. Such industrial auxiliary units include mechanical and chemical functional modules, arranged in series, dedicated to specific contaminants, e.g. suspended solids, solutes, microbiological charge, etc. Wide research and applications exist about these units to increase performances, reduce stops and maintenance best fitting the industrial sector peculiarities. Both base research on new materials and technologies and applied research on customized plants exist.

This paper proposes a review and analysis of the existing literature, prototypal solutions and full-scale applications. Deep focus is on the F&B sector. Starting from the description of the standard water pollutants and overall plant structure a set of drivers allows classifying the current research trend stressing the most promising

streams and the existing open challenges driving the forthcoming efforts in this field.

According to the introduced topic and purpose, the reminder of this paper is organized as in the following: the next Section 2 introduces the groups of water pollutants and purification technologies. Section 3 provides the drivers to study and classify the existing literature. Section 4 presents a matrix analysis of the recent developments in the field drawing trends and action lines. Finally, Section 5 concludes this paper with operative suggestions and future research opportunities.

2. Water pollutants and key purification technologies

The origin and previous use of the F&B process water heavily affects its level of purity, the pollutants inside and it drives the choice of the purification technologies. Abstracting from local peculiarities, the following sub-sections provide an overview of the most common categories of impurities within ground and underground raw water entering F&B industry processes. Finally, widely adopted purification technologies are introduced.

2.1 Pollutant categories

Solids are the first group of water contaminants. Such large group includes both dissolved (DS) and suspended (SS) substances of organic and inorganic origin. Examples of organic DS are humic acid, tannin and pyrogens, while dissolved reactive silica and salt ions exemplify inorganic DS. On the other hand, algae, fungi and bacteria are organic SS, while silt, rust, floc and clays are inorganics. Conductivity/resistivity analyses allow estimating the total DS and SS, while chemical analyses allow identifying the concentration of dissolved minerals and organics (Alvarez et al., 1997; Brunner, 2014).

Microbiological contamination is the second category of water pollutant. A distinction between viable and nonviable organisms indicates the possibility of this pollutant to proliferate within water. Bacterial colonies, pyrogenic contamination, e.g. endotoxins, are common microbiological compounds within raw water. LAL test to track endotoxins, total organic carbon (TOC), biochemical oxygen demand (BOD) and chemical oxygen demand (COD) are key indicators of the environmental health of process water. Large use of these indicators is done when analysing F&B process wastewater because of the high risk of water microbiological contamination during the process (Diná Alfonso and Bórquez, 2002).

The third group of contaminants includes minerals, from ions. Common mineral contaminants are iron, manganese, sulphates, carbonates, nitrates and nitrites, phosphates, silica, aluminium, sodium, potassium, etc. The detection of the level of such impurities is by concentration measures, water hardness and alkalinity measures. High differences occur in the quality and quantity of such impurities depending on the water origin and eventual previous use.

Heavy metals are the fourth harmful category of pollutants. Lead, arsenic, cadmium, selenium and chromium cause severe human health risks and badly interfere with the F&B processes.

Final pollutants of interest include dissolved gases, as carbon dioxide, hydrogen sulphide and radon, radioactive constituents, i.e. radionuclides, dissolved and volatile organic compounds (DOC and VOC, respectively). Depending on their nature, DOC and VOC may cause severe effect on human health. The most of them is carcinogen.

2.2 Purification technologies

Macedonio et al. (2012) provide an extensive survey about water purification technologies from different water sources stressing the crucial role of membranes in the current scenario. Basically, membranes purify water according to the ‘mechanical sieve theory’ (Wilf, 2008) even if chemical reactions and biological pollutant degradation become possible depending on the membrane materials.

Membrane technologies include filtration and reverse osmosis (RO). Filtration is distinguished, further, in micro-, ultra- and nanofiltration depending on the dimensions of the membrane pores. Figure 1 matches such dimensions to the detected pollutants.

Figure 1: membrane purification technologies

When the source water passes through the filter, under the so-called trans-membrane pressure provided by the gravity or a pump, the pollutants, e.g. bacteria, viruses, are held (Gao et al., 2011). After ultrafiltration, the water is generally ready to drink. For F&B industry use, RO is mandatory to remove the most of the solutes. In RO, the application of an external pressure to a concentrated solution forces the water molecules through a semi-permeable membrane retaining the contaminants (El-Manharawy and Hafez, 2000). The following Figure 2 presents the RO and filtration principles and the two most common filtration technologies, i.e. dead-end and cross-flow.

(a) (b)

Figure 2: RO (a) and filtration (b) technologies

The microbiological contamination removal is through an UV functional unit. UV radiation inactivates the most of microorganisms. The degree of inactivation depends on the UV dose and time exposure (in µW·s/cm2). Standard modular UV units are already widely diffuse at highly competitive cost.

Finally, in addition to such technologies, distillation, thermal processes and new frontiers adopting innovative principles, e.g. biotechnological reactors, are at a prototypal level of readiness.

3. Water technology classification drivers

To provide a comprehensive review and comparison among the existing contributions on water purification a set of classification drivers is introduced. They are the common metrics of analysis of the literature. Analytically:

- Study target. Both industrial applications and research papers are considered. Such driver directly refers to the technology readiness level of the proposed purification methodology.

- Industrial sector. Attention to the beverage and food sector is payed. Nevertheless, in presence of possible extensions to further industrial areas, the analysis highlights cross-sectorial applicability.

- Process fluid. This driver distinguishes among raw water, from ground or underground, wastewater, i.e. recovered process fluids at the industry site to implement local close-loops, and juices/water based fluids (with large percentage of water – highly diluted).

- Key investigated technology. According to the trends outlined in Section 2, deep attention goes to filtration and RO as the most immediately applicable technologies. Some frontiers are included as ‘other(s)’ if they are beyond the so-called experimental proof of concept. In addition, mandatory basic pre-treatments, e.g. chemical addition, pre-filtration etc., and post-treatments, e.g. UV, clean in place (CIP), etc., are neglected because they are common in practice.

4. Matrix analysis

Following the introduced classification drivers, a deep review of the literature, from 1992 to present, allows

drawing the matrix of Table 1 crossing the references to the metrics of analysis. Ticks indicate if the correspondent paper addresses or not the driver of analysis. Multiple ticks within the same driver indicate a combination of technologies and/or process fluid.

The global overview of the matrix shows the research trends in this research field. Some interpretative keys are in the following.

- Multiple examples of full-scale plants are proposed indicating an advanced technology readiness level of water purification technologies. This is particularly true for RO technology already widely adopted in both large and small-scale F&B plants.

- The frontier of the research, studied from different perspectives in a wide number of research papers, is on innovative materials for membranes, on the integration of multiple technologies for a low-maintenance, low-carbon and low-energy purification plant and on wastewater local recovery even under critic conditions in terms of water contaminants, e.g. meat, dairy and fruit industries.

- The integration of ultrafiltration and RO within the series of the plant functional modules is widely adopted in the F&B sector. This is to remove the suspended solids and, then, the solutes. UV is, generally, at the last stage.

- Wide interest is in water desalination, even from seawater, due to the large applicability of such solutions, worldwide.

- Despite deep studies applied to the beverage industry exist; research is more limited for the food industry mainly because of the lower attention to the water problems.

- Research on wastewater is still limited respect to raw water (including water within water-based products); it is concentrated in the most recent years even if the pioneering studies dated early ’90s state the water intensity of the F&B sector.

- Rising attention is on alternative purification technologies with very-low environmental impact. Good examples use bioreactors strongly reducing the need of chemicals. Weaknesses of such solutions are in the process time, the need of batches instead of continuous water flows and the maintenance activities on the active agents. Upgrades are mandatory before their use within the F&B industry.

Table 1: matrix analysis on water purification technologies and applications

Year Author(s)

Study target Industrial sector Process fluid Key investigated technology

Ind

ust

rial

Ap

pli

cati

on

Rese

arc

h

Pap

er

Bevera

ge

Fo

od

Mu

ltip

le/

Cro

ss-s

ecto

rial

Raw

wate

r

Wast

ew

ate

r

Juic

es/

Wate

r-b

ase

d

Mu

ltip

le/

Cro

ss-s

ecto

rial

Mic

rofi

ltra

tio

n

[0.1

-0.5

]µm

Ult

rafi

ltra

tio

n

[0.0

05-0

.05]µ

m

Nan

ofi

ltra

tio

n

[0.0

005-0

.005]µ

m

Revers

e

Osm

osi

s

Oth

er(

s)

1992 Capannelli et al.

1995 Al-Mazidi

1996 A1-Malack & Anderson

1996 Jiraratananon & Chanachai

1996 Snow et al.

1997 Alvarez et al.

1997 Jiraratananon et al.

2000 El-Manharawy & Hafez

2000 Mavrov & Bélières

2001 Al-Jayyousi & Mohsen

2001 El-Manharawy & Hafez

2002 De Bruijn et al.

2003 De Barros et al.

2004 Galambos et al.

2004 Uche et al.

Distillation

2005 Bohdziewicz & Sroka

2005 Mehta & Zydney

2005 Yazdanshenas et al.

2006 Baruah et al.

2006 De Bruijn & Borquez

2006 Cassano et al.

Distillation

2007 Cassano et al.

2007 Cassano et al.

2007 Rai et al.

2007 Rektor et al.

2008 Cassano et al.

2008 Frenkel

2008 Mirza

2008 Vourch et al.

2009 Di Giacomo & Taglieri

2009 Gokmen et al.

2009 Zularisam et al.

2010 Astudillo et al.

2010 El-Kamah et al.

Thermal

2010 Kanani et al.

2010 Onsekizoglu et al.

Distillation

2010 Yazdanshenas et al.

2011 Habibi et al.

2011 Razi et al.

2013 Kujawski et al.

2013 Sudhakaran et al.

2014 Mahmoud et al.

2014 Sorlini et al.

Thermal

2015 Alkaya & Demirer

2015 Raj & Murthy

Chemical

2016 Ghimpusan et al.

Biological

2016 Meneses & Flores

2016 Mohammad et al.

5. Conclusions

This paper presents a matrix analysis, based on relevant classification drivers, to review the literature about water purification technologies and applications for the food & beverage (F&B) industry. Starting from the introduction on the water purification issue, the pollutant categories and the most diffused technologies and methods to provide high standard water to the F&B main plant, the matrix analysis detects the research directions and open challenges.

The review of the literature, from 1992 to present, shows high attention to raw water and water based fluid treatment within the beverage industry. Minor studies are about wastewater recovery, especially for the food industry, to implement water saving local closed-loops. Base research on materials and the design of dedicated recovery functional modules are encouraged together with prototypal and full-scale plant set up to field test solutions to this challenging goal allowing strong water savings and decreasing the environmental impact, i.e. water footprint, of the F&B industry. Finally, base research and proof of concept for innovative non-mechanical green technologies are to be investigated further making such solutions ready to their industrial application.

Acknowledgements

This work is developed within the CIP Eco-innovation project no. Eco/13/630314/LESS-WATER BEV.TECH, co-funded by the Eco-innovation Initiative of the European Union, in partnership with A DUE S.p.A. and CVAR Ltd.

References

Al, H., Kochkodan, V. and Hilal, N. (2013). Hybrid ion exchange – Pressure driven membrane processes in water treatment: A review. Separation and Purification Technology ,116, 253–264.

Al-Jayyousi, O. R. and Mohsen, M. S. (2001). Evaluation of small home-use reverse osmosis units in Jordan. Desalination, 139(1), 237-247.

Alkaya, E. and Niyazi, G. (2015). Resources, Conservation and Recycling Water recycling and reuse in soft drink/beverage industry: A case study for sustainable industrial water management in Turkey. Resources, Conservation & Recycling, 104, 172–180.

Al-Malack, M. H. and Anderson, G. K. (1996). Formation of dynamic membranes with crossflow microfiltration. Journal of membrane science, 112(2), 287-296.

Al-Mazidi, S. M. (1995). Implementation of technology assessment investment techniques on water desalination. Desalination, 103(1), 39-47.

Alvarez, V., Alvarez, S., Riera, F. A. and Alvarez, R. (1997). Permeate flux prediction in apple juice concentration by reverse osmosis. Journal of Membrane Science, 127(1), 25-34.

Ang, W. L., Mohammad, A. W., Hilal, N. and Leo, C. P. (2015). A review on the applicability of integrated/hybrid membrane processes in water treatment and desalination plants. Desalination, 363, 2-18.

AQUASTAT (2014). Retrieved from http://www.fao.org/nr/water/aquastat/tables/WorldData-Withdrawal_eng.pdf

Astudillo, C., Parra, J., González, S. and Cancino, B. (2010). A new parameter for membrane cleaning evaluation. Separation and Purification Technology, 73(2), 286-293.

Baruah, G. L., Nayak, A. and Belfort, G. (2006). Scale-up from laboratory microfiltration to a ceramic pilot plant: Design and performance. Journal of membrane science, 274(1), 56-63.

Bohdziewicz, J. and Sroka, E. (2005). Integrated system of activated sludge–reverse osmosis in the treatment of the wastewater from the meat industry. Process Biochemistry, 40(5), 1517-1523.

Brunner, G. (2014). Properties of pure water. In Brauer A. (ed.), Supercritical Fluid Science and Technology, 9-93. Elsevier, Oxford (United Kingdom).

Capannelli, G., Bottino, A., Munari, S., Ballarino, G., Mirzaian, H., Rispoli, G., Lister D.G. and Maschio, G. (1992). Ultrafiltration of fresh orange and lemon juices. Lebensmittel Wissenschaft und Technologie, 25(6), 518-522.

Cassano, A., Figoli, A., Tagarelli, A., Sindona, G. and Drioli, E. (2006). Integrated membrane process for the production of highly nutritional kiwifruit juice. Desalination, 189(1), 21-30.

Cassano, A., Marchio, M. and Drioli, E. (2007). Clarification of blood orange juice by ultrafiltration: analyses of operating parameters, membrane fouling and juice quality. Desalination, 212(1), 15-27.

Cassano, A., Donato, L. and Drioli, E. (2007b). Ultrafiltration of kiwifruit juice: operating parameters, juice quality and membrane fouling. Journal of Food Engineering, 79(2), 613-621.

Cassano, A., Donato, L., Conidi, C. and Drioli, E. (2008). Recovery of bioactive compounds in kiwifruit juice by ultrafiltration. Innovative Food Science & Emerging Technologies, 9(4), 556-562.

De Barros, S. T. D., Andrade, C. M. G., Mendes, E. S. and Peres, L. (2003). Study of fouling mechanism in pineapple juice clarification by ultrafiltration. Journal of Membrane Science, 215(1), 213-224.

De Bruijn, J., Venegas, A. and Borquez, R. (2002). Influence of crossflow ultrafiltration on membrane

fouling and apple juice quality. Desalination, 148(1), 131-136.

De Bruijn, J. and Bórquez, R. (2006). Analysis of the fouling mechanisms during cross-flow ultrafiltration of apple juice. LWT-Food Science and Technology, 39(8), 861-871.

Di Giacomo, G. and Taglieri, L. (2009). A new high-yield process for the industrial production of carrot juice. Food and bioprocess technology, 2(4), 441-446.

Diná Alfonso, M. and Bórquez, R. (2002). Review of the treatment of seafood processing wastewaters and recovery of proteins therein by membrane separation processes – prospects of the ultrafiltarion of wastewaters from the fish meal industry. Desalination, 142, 29-45.

Echavarría, A. P., Torras, C., Pagán, J. and Ibarz, A. (2011). Fruit juice processing and membrane technology application. Food Engineering Reviews, 3(3-4), 136-158.

El-Kamah, H., Tawfik, A., Mahmoud, M. and Abdel-Halim, H. (2010). Treatment of high strength wastewater from fruit juice industry using integrated anaerobic/aerobic system. Desalination, 253(1), 158-163.

El-Manharawy, S. and Hafez, A. (2000). Technical management of RO system. Desalination, 131(1), 173-188.

El-Manharawy, S. and Hafez, A. (2001). Water type and guidelines for RO system design. Desalination, 139(1), 97-113.

Eltawil, M. A., Zhengming, Z. and Yuan, L. (2009). A review of renewable energy technologies integrated with desalination systems. Renewable and Sustainable Energy Reviews, 13(9), 2245-2262.

Eurostat (2015). Energy, transport and environment indicators. Publications Office of the European Union, Luxembourg.

FAO (2016). Retrieved from http://www.fao.org/nr/water/aquastat/main/index.stm.

Frenkel, V. S. (2008). Membrane in water and wastewater treatment. In Proceedings of the World Environmental and Water Resources Congress (pp. 316-324), May 12-16, 2008, Honolulu, Hawaii.

Galambos, I., Molina, J. M., Járay, P., Vatai, G. and Bekássy-Molnár, E. (2004). High organic content industrial wastewater treatment by membrane filtration. Desalination, 162, 117-120.

Gao, W., Liang, H., Ma, J., Han, M., Chen, Z. L., Han, Z. S. and Li, G. B. (2011). Membrane fouling control in ultrafiltration technology for drinking water production: a review. Desalination, 272(1), 1-8.

Geise, G. M., Lee, H. S., Miller, D. J., Freeman, B. D., McGrath, J. E. and Paul, D. R. (2010). Water

purification by membranes: the role of polymer science. Journal of Polymer Science Part B: Polymer Physics, 48(15), 1685-1718.

Ghaffour, N., Missimer, T. M. and Amy, G. L. (2013). Technical review and evaluation of the economics of water desalination: current and future challenges for better water supply sustainability. Desalination, 309, 197-207.

Ghimpusan, M., Nechifor, G., Nechifor, A. C., Dima, S. O. and Passeri, P. (2016). Case studies on the physical-chemical parameters' variation during three different purification approaches destined to treat wastewaters from food industry. Journal of Environmental Management, in press.

Girard, B., Fukumoto, L. R. and Sefa Koseoglu, S. (2000). Membrane processing of fruit juices and beverages: a review. Critical reviews in biotechnology, 20(2), 109-175.

Gökmen, V., Açar, O. C., Serpen, A. and Süğüt, I. (2009).

Modeling dead‐end ultrafiltration of apple juice using artificial neural network. Journal of food process engineering, 32(2), 248-264.

Grimm, J., Bessarabov, D. and Sanderson, R. (1998). Review of electro-assisted methods for water purification. Desalination, 115(3), 285-294.

Habibi, A., Aroujalian, A., Raisi, A. and Zokaee, F. (2011). Influence of operating parameters on clarification of carrot juice by microfiltration process. Journal of Food Process Engineering, 34(3), 860-877.

Hinkebein, T. E. and Price, M. K. (2005). Progress with the desalination and water purification technologies US roadmap. Desalination, 182(1), 19-28.

Jiraratananon, R. and Chanachai, A. (1996). A study of fouling in the ultrafiltration of passion fruit juice. Journal of Membrane Science, 111(1), 39-48.

Jiraratananon, R., Uttapap, D. and Tangamornsuksun, C. (1997). Self-forming dynamic membrane for ultrafiltration of pineapple juice. Journal of Membrane Science, 129(1), 135-143.

Kanani, D. M., Fissell, W. H., Roy, S., Dubnisheva, A., Fleischman, A. and Zydney, A. L. (2010). Permeability–selectivity analysis for ultrafiltration: Effect of pore geometry. Journal of membrane science, 349(1), 405-410.

Kujawski, W., Sobolewska, A., Jarzynka, K., Güell, C., Ferrando, M. and Warczok, J. (2013). Application of osmotic membrane distillation process in red grape juice concentration. Journal of Food Engineering, 116(4), 801-808.

Macedonio, F., Drioli, E., Gusev, A. A., Bardow, A., Semiat, R. and Kurihara, M. (2012). Efficient technologies for worldwide clean water supply. Chemical Engineering and Processing: Process Intensification, 51, 2-17.

Mahmoud, K. A., Mansoor, B., Mansour, A. and Khraisheh, M. (2015). Functional graphene

nanosheets: the next generation membranes for water desalination. Desalination, 356, 208-225.

Mavrov, V. and Bélières, E. (2000). Reduction of water consumption and wastewater quantities in the food industry by water recycling using membrane processes. Desalination, 131(1), 75-86.

Mehta, A. and Zydney, A. L. (2005). Permeability and selectivity analysis for ultrafiltration membranes. Journal of Membrane Science, 249(1), 245-249.

Meneses, Y. E. and Flores, R. A. (2016). Feasibility, safety and economic implications of whey-recovered water in cleaning-in-place systems: A case study on water conservation for the dairy industry. Journal of dairy science, 99(5), 3396–3407.

Mirza, S. (2008). Reduction of energy consumption in process plants using nanofiltration and reverse osmosis. Desalination, 224(1), 132-142.

Mohammad, A. W., Teow, Y. H., Ang, W. L., Chung, Y. T., Oatley-Radcliffe, D. L. and Hilal, N. (2015). Nanofiltration membranes review: Recent advances and future prospects. Desalination, 356, 226-254.

Mondal, S., Hsiao, C. L. and Ranil Wickramasinghe, S. (2008). Nanofiltration/reverse osmosis for treatment of coproduced waters. Environmental Progress, 27(2), 173-179.

Onsekizoglu, P., Bahceci, K. S. and Acar, M. J. (2010). Clarification and the concentration of apple juice using membrane processes: A comparative quality assessment. Journal of Membrane Science, 352(1), 160-165.

Pradeep, T. (2009). Noble metal nanoparticles for water purification: a critical review. Thin solid films, 517(24), 6441-6478.

Rai, P., Majumdar, G. C., Gupta, S. D. and De, S. (2007). Effect of various pretreatment methods on permeate flux and quality during ultrafiltration of mosambi juice. Journal of Food Engineering, 78(2), 561-568.

Raj, R. and Murthy, S. (2015). Increasing the Sludge Treatment Efficiency of a Food Processing Industry. International Research Journal of Engineering and Technology. 2(6), 53–57.

Razi, B., Aroujalian, A., Raisi, A. and Fathizadeh, M.

(2011). Clarification of tomato juice by cross‐flow microfiltration. International Journal of Food Science & Technology, 46(1), 138-145.

Rektor, A., Kozak, A., Vatai, G. and Bekassy-Molnar, E. (2007). Pilot plant RO-filtration of grape juice. Separation and Purification Technology, 57(3), 473-475.

Snow, M. J., de Winter, D., Buckingham, R., Campbell, J. and Wagner, J. (1996). New techniques for extreme conditions: high temperature reverse osmosis and nanofiltration. Desalination, 105(1), 57-61.

Sorlini, S., Gialdini, F. and Collivignarelli, M. C. (2014). Survey on full-scale drinking water treatment plants

for arsenic removal in Italy. Water Practice and Technology, 9(1), 42-51.

Sudhakaran, S., Lattemann, S. and Amy, G. L. (2013). Appropriate drinking water treatment processes for organic micropollutants removal based on experimental and model studies—a multi-criteria analysis study. Science of the Total Environment, 442, 478-488.

Uche, J., Serra, L. and Sanz, A. (2004). Integration of desalination with cold-heat-power production in the agro-food industry. Desalination, 166, 379-391.

Vourch, M., Balannec, B., Chaufer, B. and Dorange, G. (2008). Treatment of dairy industry wastewater by reverse osmosis for water reuse. Desalination, 219(1), 190-202.

Wilf, M. (2008). Membrane types and factors affecting membrane performance. National Water Research Institute, Fountain Valley, CA.

Yazdanshenas, M., Tabatabaee-Nezhad, S. A. R., Soltanieh, M., Roostaazad, R. and Khoshfetrat, A. B. (2010). Contribution of fouling and gel polarization during ultrafiltration of raw apple juice at industrial scale. Desalination, 258(1), 194-200.

Yazdanshenas, M., Tabatabaeenezhad, A. R., Roostaazad, R. Khoshfetrat, A. B. (2005). Full scale analysis of apple juice ultrafiltration and optimization of diafiltration. Separation and Purification Technology, 47(1), 52-57.

Zularisam, A. W., Ismail, A. F., Salim, M. R., Sakinah, M. and Matsuura, T. (2009). Application of coagulation–ultrafiltration hybrid process for drinking water treatment: optimization of operating conditions using experimental design. Separation and Purification Technology, 65(2), 193-210.