Final Report Summary - AQUAFIT4USE (Water in industry, fit-for-use sustainable water use in chemical, paper, textile and food industry)
Executive summary:
AQUAFIT4USE has brought innovative solutions to increase the sustainable use of water in industry in four important water intensive sectors: chemical, paper, textile and food.
By the development and piloting at industrial level of new, reliable cost-effective technologies, tools and methods, big steps have been made towards the sustainable use of water resulting in significant reduction of the fresh water needs, closing the water cycle, mitigation of the environmental impact and the production and use of water in accordance with the specifications of industry for the different processes and applications, 'water fit-for-use'. Supporting the industry to secure this vital resource and to decouple the water use and the related environmental impact from economic growth are important issues to support European Union (EU) policy on competitiveness, resource efficiency and environment.
Project context and objectives:
By consuming several billions m³ of water a year, European industry has a significant impact on available water sources. Legislation, stringent discharge standards, higher process and product demands and increasing water scarcity force industry to ensure higher water quality, resulting in higher costs.
'For the water consuming industry, water is no longer regarded as a commodity, consumable or utility but as a highly valuable resource, a vital element used in close conjunction with the production processes. Industries want to become more and more independent of public and private parties for the supply of process water and the treatment of wastewater. Furthermore, they want to use water qualities according to their own specifications, fit-for-use'.
This vision on sustainable water use and the great economic importance of water for the industrial sector was already defined in the first vision document and Strategic Research Agenda (SRA) of the European Water Platform (WTP) in 2006. In the updated SRA in 2011, more emphasis was put at water quality definition and water-fit-for-use, closure the water cycle and a more integrated approach.
Four pillars for sustainable water use in industry
AQUAFIT4USE is built on four pillars:
1. Water fit-for-use
Water fit-for-use is the basis of the project. In the current situation, most of the industries are not able to answer the question 'What water quality is really needed?' Knowledge on the effect of the water quality on process, product quality and health issues is not available. This makes that industries often choose for far better water qualities than needed. However, sustainable water use means: use water of right quality, 'fit-for-use'. AQUAFIT4USE gives not only an answer to the question 'What is the minimum water demand and water quality' that is really needed, but also to questions like:
- How can these water qualities be produced and maintained?
- How can these water qualities be monitored and controlled?
- What are the effects of using lower water quality?
These questions first need to be answered, before the industries can take further steps in sustainable water use, closing the water cycle and use of different water sources.
2. Integrated sustainable water use in industry
Sustainable water use requires an holistic approach. Within AQUAFIT4USE, there is a strong focus on the integration of all water related aspects, like new sources, energy, waste(s), process, product and environment. This is carried out in a systematic and structured approach, that ensures that all important mass and energy flows are taken into account, and scenarios for optimisation are developed including the use of process integration and energy and water pinch techniques. Environmental impact assessment is part of this approach.
3. Strong industrial participation
Within AQUAFIT4USE, 22 of the 34 partners are industries, 9 industrial suppliers and 13 end-users. The end-users, representing the four major European Union (EU) water consuming industries, paper, chemistry, food and textiles, were selected on their annual volume of water consumption and are complementary towards water research needs and know-how.
4. Cross-sectorial solutions
The four target industries are dealing partly with similar problems and challenges, but do have also their own specific questions. From previous European and national research projects, the developed knowledge can be summarized as follows:
Chemical industry: The focus in the past was on treatment of strongly polluted effluents; removal of trace elements; treatment of water, with emphasis on reuse in cooling systems, i.e. focus on corrosion problems and chemical conditioning. Water loop closure for other applications got limited attention.
Paper industry: A lot of effort is given to water saving and closing of water circuits, thereby substantially reducing the environmental impact; process modelling and automation and Kidney technologies as internal process water treatment are essential elements in this strategy. A number of problems around the removal of substances are not solved yet and further closing the water cycle causes new problems. As still some 2 billion cubic meter of fresh water is currently used, there is still a challenge.
Food industry: The main point of attention is water quality in relation to product quality and health. Therefore water reuse is only implemented to a limited extent. Besides, water treatment measuring and monitoring is a major concern.
Textile industry: It pays already a lot of attention to sustainable water use. Because most textile companies are small and medium-sized entreprises (SMEs), handling small orders, the composition of water streams is highly variable and therefore often a problem.
Objectives
The overall objective of AQUAFIT4USE is the development of new, reliable, cost-effective technologies, tools and methods for sustainable water supply, use and discharge in the main European water consuming industries in order to:
- reduce high quality water consumption and fresh water needs;
- mitigate environmental impact;
- produce and apply water qualities in accordance with industrial own specifications (fit - for - use) from all possible sources;
- contribute to a far-going closure of the water cycle while;
- reducing water relating costs (intake, treatment, re-use, closed loops, discharge);
- improving product quality and process stability;
- increase independency and flexibility;
- better management of health and safety risks relating to water use.
This overall objective resulted in the following science and technology(S&T) objectives:
Objective 1: Water quality definition for processes, utilities and environment
As mentioned before, a good insight in the existing water system and especially in the water quality demands are basic requirements for sustainable industrial water systems. A systematic generic approach for the definition of the specific water quality demands (methodology) should be developed. Additionally, a detailed definition of specific water quality demands in the various industrial process steps of the four sectors is needed, as well as cross-sectorial parameter definition on scaling, biofouling, safety and health.
Objective 2: Integrated modelling and control of industrial water systems
Models of water treatment technologies and the various process steps (unit-process models) are the building blocks for modelling total water industrial systems, with the support of a newly developed Integrated water modelling methodology. The final model will be used in the case studies for simulation and optimisation. Also insight needs to be gathered in uncertainty and risks associated to alternative the water systems.
Objective 3: Practicable innovation in water treatment technologies
The development of new water treatment concepts and technologies is from the main technological objective of AQUAFIT4USE. The focus was on two levels:
- the development of new technologies to solve specific problems in the area of selective removal of specific substances, biofouling and scaling prevention, improved disinfection, desalination;
- the development and testing of different treatment concepts in practice. Combination of several treatment technologies (treatment trains) are needed to find solutions for the complex water issues and to produce water 'fit-for-use'.
Objective 4: integration and validation of solutions:
The interaction with other water-related issues, like process stability, product quality and energy and wastes, is regarded in more detail. Validation of the solutions, also using methodologies for environmental assessment are part of this objective.
Project results:
AQUAFIT4USE has brought about a lot of innovative and applicable results, that were very helpful to convince industries in different sectors on the feasibility of sustainable water use in their specific situation. Real steps forward have been made, giving answers to the main challenges of sustainable water use and finding solutions for the reuse of water, further closing of the water cycle and using alternative water sources without making concessions to product quality, health and safety.
In AQUAFIT4USE three types of results can be distinguished:
1. Solutions to improve water management
In this area a broad list of results can be mentioned: tools for simulation and optimisation of water systems, models, knowledge on water quality demands for processes and other water applications, measuring and monitoring equipment and assessment tools. Within this framework also other water related issues and integration aspects were explored.
2. Technological solutions to solve common industrial problems
Specific technological problems and challenges that are common for different sectors have been addressed by developing new technologies and adapting existing technologies for the specific situation.
3. Treatment trains as custom made solutions
Existing and new technologies were combined leading to innovative solutions to improve the water systems of different industries. These solutions were tested at pilot scale at various industrial locations, leading to a lot of practical experience.
Water quality management: The key to sustainable water use
Sustainable water use in industry starts with a good insight in the industrial water system, with a strong emphasis on the water quality issues. Answers to the next questions should be provided:
- What is the water quality that is really needed in a process or other application?
- How can this water quality be produced and/or maintained?
- What will be the effect of using a different water source?
- How can we monitor and control the water quality?
Water quality management (WQM) methodology
For answering the above mentioned questions a systematic step-by-step approach has been developed, the WQM methodology. This methodology is coupled with newly developed software tool for industrial water management WESTforINDUSTRY.
The steps of the WQM methodology are listed below:
1. definition of existing water system (information gathering);
2. setting up the water network;
3. parameter selection, assessment and standardisation (water quality definition);
4. supplying WESTforINDUSTRY with input;
5. simulation of the water network;
6. optimisation of the water network;
7. output analysis and processing;
8. water quality control.
It is very important to determine the system boundaries in the system definition phase, deciding also at what level a water management project will be carried out and which parts of the system (factory, site) will be involved.
Water-fit-for-use
A procedure for water quality definition was developed, as part of WQM, to determine the actual water quality needed for a specific process or treatment step. Important steps are the selection of the relevant parameters, the parameter assessment and standardisation, all related to the five defined quality aspects: product quality, product safety, process water function, machinery and pipes and health and environment. Based on this procedure the water qualities for selected processes in the four sectors have been determined and summarised in public reports and in the data base of WESTforINDUSTRY.
Water quality control (WQC)
For water quality control a quality system for the complete water system was developed. The method uses the principles of HACCP, the quality system for safe food production that is applied for years in almost every Food company. For water quality control, the approach is extended with other quality issues, like product quality, process water function, and health and working conditions, all being part of the water quality definition.
Modelling in industrial water systems
The development of models and the verification / validation of these models on real scenarios provided by the industrial partners was very important for the availability of simulation tools able to reproduce the water circuits. A mathematical model library that reproduces the most relevant wastewater treatment technologies studied within the AQUAFIT4USE project and other treatment technologies has been developed. These treatment technologies compiled in the model library, are classified in three categories:
1) solid-liquid separation units such as membrane technologies, settlers and electrochemical separation processes;
2) biological units like activated sludge units and membrane bioreactors;
3) chemical processes like disinfection units, coagulation-flocculation processes.
WESTforINDUSTRY: A software tool for model based optimisation of water systems
Description of the tool
In WESTforINDUSTRY knowledge about WQM, water treatment and modelling is brought together in a model-based software framework. The tool allows for defining, simulating (including various forms of graphical visualisation) and optimizing industrial water networks in a very intuitive way. The user is able to define the boundaries of the optimisation window by choosing the treatment technologies and the place where these technologies should be positioned. The software can then calculate the effect of each scenario and give a range of results which can be compared and evaluated based on different criteria (e.g. costs, fresh water use and discharge).
Tool development
A review of recent literature on industrial process modelling showed that the use of process integration tools has increased especially over the past two decades, and is mainly applied to focus on resource conservation, pollution prevention and energy management. Mathematical models to simulate industrial processes are used in a wide range of industrial sectors, but have especially emerged within industrial sectors with large scale production facilities, such as pulp and paper, petrochemical, synthetic chemical and pharmaceutical.
Testing and benchmarking WESTforINDUSTRY
Bench mark water network
The optimisation methodology proposed and implemented in the WESTforINDUSTRY software has been first verified and tested in the benchmark water network (BWN), that was defined in the scope of the project. The theoretical 'benchmark case-study' has been created to be used as a simple and common example of a water network subject to optimisation and that is assumed to contain the most important features typically found in industrial water networks. It has been successfully used as a common platform for discussion of water network visualisation, optimisation tools capability, process modelling methodology, needs for development of the simulation platform, cost analysis, optimisation methodology, etc.
Case studies with WESTforINDUSTRY
Holmen was used as a benchmark case. The information and the results obtained during the pilot trials were used for the development of mathematical models. These models, the data and the application of the WESTforINDUSTRY at Holmen's circuits were an important starting point for the future development of the tool.
Measuring and monitoring: Evaluation of sensors
To manage wastewater treatment processes in the industry, devices for measuring water quality parameters are needed. The choice of an instrument for a given process is not easy and is often made according to the basic metrological characteristics given by the suppliers. However these characteristics are not always sufficient and may even lead to a wrong choice: most suppliers do not take into account the real operating context with varying process conditions. This is why a procedure for the evaluation of sensors and analysers of water quality was developed.
Fast monitoring micro-organism: 145 new gene probes
As microbial growth and its relationship with health related issues is a key point in industrial water reuse policies, specific activities in this project were devoted to biofilm and corrosion detection methods and devices.
Another key aspect within the project was the assessment and definition of the actual microbiological water quality required for each process, as it is needed for the successful implementation of new treatment technologies for water reuse.
Together with the application of cultivation-based methods for microbial detection, a strong focus was given to the development of molecular methods based on Fluorescence in situ hybridisation (FISH) for microbial analysis in order to:
(i) describe various population communities completely and not only partial;
(ii) improve the current microbiological knowledge in the industries;
(iii) increase the speed of analysis in order to quickly evaluate newly implemented processes;
(iv) develop new tools to monitor micro-organisms which are process relevant, but difficult to cultivate or non-cultivable.
Holistic environmental assessments
To achieve the sustainability objective of this project, it was essential to check whether new technologies and reuse options allowed reducing environmental impacts of industrial water treatment. Two levels of scales are investigated. Firstly, the effect of water treatment processes on the actual toxicity of effluent was evaluated with the whole effluent assessment (WEA) methodology.
Technological solutions to solve industrial common problems
Water recycling and reuse present common concerns, independent from the industrial sector. These are biofouling, scaling, treatment of concentrate and saline streams, membranes management and processes to increase retention rate and limit membrane fouling, enhancement of bio-treatment, removal of COD and recalcitrant contaminants, effluent polishing for suspended solids removal and disinfection. The AQUAFIT4USE project proposed solutions that could be applied to solve these common problems.
The focus was on these specific topics to get a clear view on the advantages and bottlenecks of current processes and by trying to minimise the gap by new technological developments. On the basis of wastewater characterisation and definition of required water quality for each industry, different technologies and processes were tested and/or evaluated, in order to define the following:
- New treatment lines to obtain the water quality target, considering cost effectiveness, reliability, minimisation in waste and concentrate production. These new treatment lines are focused more particularly on internal recycling.
- New technologies that could be included in these treatment lines.
Most of these studies constituted preliminaries for pilot trials at location.
Biofouling and scaling prevention technologies
In the area of biofouling and scaling prevention AQUAFIT4USE focussed on three technologies: Denutritor, Nanosilver and FACT.
Denutritor - a biofiltration based biofouling prevention technology - was successfully tested at the effluent of the waste water treatment plant (WWTP) of a chemical plant in Sweden, resulting in an about eight-fold reduction of the biofouling potential, increasing the possibilities of reuse of the water for cooling and other industrial applications.
Denutritor was also tested at the Ben&Jerry's ice cream factory for the removal of (pathogenic) micro-organisms from rain water. It showed that Denutritor can reduce but not fully remove coliforms, E. coli and pathogenic bacteria present in collected rainwater. The amount of viable bacteria can additionally be reduced with 90 - 99 % efficiency by exposure to UV doses between 50 and 2500 J/L. During these laboratory tests, three new types of biofouling monitors were evaluated. The increase of protein concentration on the monitors appeared to be a good indicator of the biofouling potential of the synthetic WWTP effluent water tested. Biofouling monitors made from silicon or polyethylene (PE) tubes were finally selected for use during the further pilots.
Selective removal of substances
In a first part of the work, the potential of a new reductive technology was evaluated for the removal of brominated compounds and organic halides (AOX) in general. The reductive agent investigated was zerovalent iron (ZVI), which is extensively applied in groundwater treatment, but is an emerging technology for wastewater treatment.
Batch screening tests were performed for a broad range of wastewaters and ZVI types. For AOX, removal efficiencies were usually below 50 %, even at high iron concentrations. Removal efficiencies were best with nano-scale iron. For the removal of brominated compounds, efficiencies were on average higher than for AOX and reached up to 99 %.
Disinfection
The state-of-art study on innovative technology for the disinfection of industrial reused water and reclaimed water, showed that monochloramine has been found to be more effective than free chlorine in controlling biofilms and coliform bacteria in systems with long detention times due the lower decay rate of chloramine.
Innovative disinfection technologies are mostly physical technologies (pulsed electric field, radiofrequency power, ultrasound (US)) and photosensitisation of nano-particles(TiO2). They seem to be efficient against micro-organisms depending on many parameters.
Though they are not used a lot at this time to treat industrial water, these technologies can improve classical disinfection processes when used in association. The efficiency of US when used alone is not very high, but in association with other disinfection processes, US can be very interesting to reduce dosage or contact time.
There are only limited literature data on disinfection processes for industrial water reuse. Physical processes could be an interesting alternative to industries in order to reduce their chemicals consumption and to limit the by-product formation.
From above discussed experimental results, the following conclusions were stated:
- Spores of Bacillus subtilis are extremely resistant and no significant improvement in reduction of spores was observed with ultrasound treatment at low and high frequency.
- In comparison to ultrasound treatment of Bacillus subtilis spores, the reduction of E.coli is achieved in a very short treatment time.
- The higher the frequency, the better the inhibition efficiency for E.coli.
- The longer the treatment time, the better the inhibition efficiency for E.coli.
- The highest efficiency of inhibition was observed at 817 kHz for both 5 and 10 min.
- The treatment at 817 kHz and 5 minutes presents optimal conditions that allow a decrease of E.coli K12 concentration for 2.97 ± 0.58 log in demineralised water for the ultrasound equipment used in this study.
Saline streams
One of the objectives of AQUAFIT4USE was the development of new sustainable technologies for the treatment of saline streams. Three types of technologies have been considered:
a) Capacitive deionisation (CapDI)
In a CapDI system, salts are removed from the saline stream by the principle of capacitive deionisation.
Main results achieved are listed below:
- Developed modular CapDI system - A CapDI system based on unit modules has been developed that is now in production. Size of the system can be easily adjusted by installing more modules.
- Improved coated electrodes - Carbon coated electrodes showed to have excellent salt removal capacity, when compared to good quality commercial electrodes.
- Improved spacers: a low pressure drop spacer allows higher flow rates, resulting in the possibility to effectively treat a larger volume of water. This has been verified in the field.
- Improved membranes - PC cell is able to produce ion exchange membranes at significantly reduced cost compared to those of Tokuyama (the industry standard), without loss of desalination performance.
- Better understanding of performance relations for different types of water. It is beneficial to increase the total salt flux presented to the CapDI system, when the total amount of salt removed is of most interest. For cooling tower applications, where the salt concentration of the treated stream is very low, this means that the flow should be maximised.
- Use of constant current operation to enable energy re-use. More than 75 % of energy can be recovered at very low current densities. At practical conditions, more than 40 % of energy can be recovered.
- Experience of running a pilot system and full scale system on a cooling tower at two different sites.
- Knowledge on filtering requirements for pretreatment for CapDI for cooling tower application.
b) Membrane distillation-crystallisation (MDC) for highly concentrated saline streams
In MDC the salts are concentrated and crystallised by a membrane distillation process:
- Salt solutions can be concentrated up to saturation by membrane distillation (MD) without loss of specific flux (flux corrected for driving force).
- During crystallisation, a rapid flux decline is observed in the MD operation. It is expected that this is typically the case with salts like NaCl, but not with salts like CaCO3, because the lower temperature near the membrane due to temperature polarisation is favourable for this type of salts with an inverse solubility-temperature profile.
- Applying osmotic distillation (OD), a type of membrane distillation instead of MD gives a less sudden flux decline during crystallisation, but has to be optimised e.g. by adding seeds to prevent crystallisation on the membrane which still occurred in the experiments performed.
c) Evapoconcentration
Evapoconcentration is a technology commonly used to treat salty waste waters and results in relatively clean water (potentially suitable for reuse) and highly concentrated brine or precipitates. However, this technology is energy consuming and it is necessary to design / develop small scale units which are thermally optimised (way of evaporation and the heat recovery system), and use standardised compounds. The design must as well take into consideration the corrosion aspect. The objective of the work done was then to define such type of units for the treatment of industrial waste waters for the pulp and paper, textile and chemistry sector.
Use of micro-turbine:
- The combined heat and power concept with mechanical vapour recompression and a micro-turbine proved to be an interesting and energy efficient approach for evaporation.
- However, it could not be tested in practice because the chosen scale for demonstration was too small. Therefore, it was evaluated in a case study corresponding to landfill leachates treatment for which industrial data were available. Three different configurations were evaluated by calculations. For such an application (landfill leachates), the micro-turbine could be an interesting technology to produce heat and electricity from biogas.
Treatment trains as custom made solution - reliable and cost-effective
The objectives in this area was the identification of the best new (combinations of) water technologies to reduce environmental impacts by advanced closure of the water cycle and produce the required water quality for re-use. The work concerned the laboratory and preparations of pilot trials in the two industrial paper mills and two textile mills and case studies in all four sectors
Laboratory trials pulp and paper sector
In the pulp and paper industry a lot of effort is put into water saving and closing water circuits, also reducing substantially the environmental impact, both by process modelling and Kidney technologies as internal process water treatment. Kidney technology aims at removing specific substances from the recirculating process water. However, a number of problems around the removal of substances are not solved yet and further closing of the water cycle causes other problems.
Challenges for water reuse in the pulp and paper industry are the following:
- the elimination of residual (soluble) COD and BOD which can both affect the production process and the paper quality;
- the removal of sticky solids and suspended solids, which can induce plugging of pipes and showers, deposit formation, abrasion, loss of tensile strength;
- the treatment of concentrate streams containing calcium, sulphate, chloride and organics which can lead to salt accumulation in case of water loop closure, corrosion, scaling of pipes and showers in the paper production process.
The removal of calcium carbonate is crucial in the last case.
Therefore, there is a need to find new and reliable (combinations of) technologies to solve this challenges to achieve the water quality target for water re-use and which are tailored to suit product demands and standards.
Based on the waste water characterisation and the defined water quality requirements for paper mills, new treatment lines focused on internal recycling were defined to reach the water quality target including effectiveness, reliability and minimisation in waste and concentrate production.
The emphasis was on different key steps in the overall treatment train:
- Biological treatment: anaerobic processes and MBR;
- Filtration processes: 3FM high speed technology and nanofiltration;
- Tertiary treatments to reduce recalcitrant COD and scaling: advanced oxidation processes, coagulation, precipitation;
- Integration of processes (evapoconcentration, electrodialysis and softening) in the treatment line to treat the concentrate streams containing calcium, sulphate, chloride, organics, to minimize the waste production and enhance internal recycling.
Technologies were tested at lab scale on the wastewaters from two different paper mills: Hamburger Rieger (HRT), producing high quality coated and uncoated board from recycled paper and Holmen Paper Madrid (HOL), producing standard newsprint, improved newsprint (higher brightness) and lightweight coated paper (for magazines).
The most important findings for newsprint paper mills are the following:
- Anaerobic pre-treatment showed very good performance treating a low organic load wastewater as the effluent of a 100 % recycled NP/LWC paper mill, and assisting the aerobic stage on removing organics and sulphates; besides it produced enough biogas for being considered as cost-effective. Wastewater quality after biological treatment was suitable to perform a posterior membrane treatment.
- Membrane treatment by UF + RO is able to generate permeates of high water quality, fulfilling all the requirements for being used in critical points of the paper machine that require a very high water quality.
However, silica is a main issue for reuse as it leads to a reduction of recovery for RO treatment and scaling in UF treatment:
Different chemicals have been tested to achieve the silica removal efficiencies necessary to avoid silica scaling on RO membranes in the advanced treatment of the paper mill effluent: 80 - 90 % silica removal was achieved by coagulation at different pHs. Coagulation treatment can be as efficient as required (greater than 95 % removal), however, the costs are relatively high due to high dosages required and/or the use of complex chemicals.
Softening at high pH with the addition of magnesium compounds can also be used and efficient removal of silica is achieved down to the required values.
Further treatment of RO concentrates is needed for liquid discharge in municipal waste water to complain with the legislation. A further treatment is needed: Evapo-concentration is well adapted to treat membrane concentrates: the amount of final waste to be disposed is reduced and the produced water meets the water quality criteria for reuse in the paper production.
AOPs applied to membranes concentrates allow to reduce the recalcitrant COD, TOC and colour. The water can then be sent to the (closest municipal) WWTP.
In general:
- Ozone and AOPs were validated for both type of paper mills as final polishing treatment for water to be reused concerning disinfection, color removal, TOC and COD removal and biodegradability improvement.
Laboratory trials textile sector
The current situation reflects that the typical textile company prefers to use fresh high quality water in all production operations processes after softening to preserve the quality of their final products. Wastewaters are mostly discharged without any pre-treatments into the sewer, since sophisticated wastewater treatment technologies are mainly not affordable for small to medium-sized textile companies. Water reuse in the textile finishing industry needs the development of very specific processes (which can also be chosen among the already available ones) in order to produce the 'fit-for-use' water for a specific process (or a few processes).
Case studies: The proof of applicability
Paper sector
Based on laboratory work where a range of new and reliable (combinations of) technologies were evaluated, the most promising concepts have been scaled up successfully in different pilot trials. The focus has been on water quality targets for water reuse in-line with product demands and standards whilst avoiding any negative impact on paper machine runability and paper quality. As a result, customised pilot plant trains have been implemented.
Tests at Hamburger Rieger
Extensive tests involving seven simultaneously operated water treatment technologies were run at a German paper and board mill from February to September 2011. The dimensions of the trials were extraordinary in terms of both volume flows and the variety of treatment lines. Various processes could be operated in parallel as well as in series.
The technological and economic benefits of tailor-made water treatment lines have been investigated by comprehensive pilot trials. The trials were aimed at increasing the water reclamation rate of paper mills. Individually, each of the chosen treatment technologies represented the state-of-the-art in the paper industry in a particular case. By combining these advanced technologies to customised treatment trains, innovative research enabled breaking new ground in forward-looking water treatment.
The special composition of paper mill wastewaters calls for tailor-made treatment concepts. Consequently, the following main results have been derived:
- Water softening has been proven as an essential pre-treatment whenever membrane processes are to be used.
- Recirculation of nanofiltration concentrates in the anaerobic reactor after pre-treatment by ozone oxidation turned out to be unreliable in some cases.
- Using evapo-concentration for NF concentrate disposal has been evaluated as an alternative treatment technology.
- Two treatment lines including biological and physico-chemical processes have been proven to be technologically as well as economically viable:
(1) anaerobic treatment -greater than conventional activated sludge process - greater than softening - greater than pre-filtration - greater than nanofiltration - greater than evapo-concentration of concentrates;
(2) anaerobic treatment - greater than softening - greater than MBR - greater than nanofiltration - greater than evapo-concentration of concentrates.
Holmen
This paper mill, producing recycled paper from 100 % recovered paper, has optimised its water circuits for a longer period. Nowadays, they are consuming about 8 m3/T, which is lower than the estimated consumption in the BREF document for papers mills manufacturing newsprint paper. The required quality for any further closure of the circuits is very high, close to potable water quality.
% LDuring AQUAFIT4USE, after a deeper study of the current situation, two pilot plants with a capacity of 1 m3/h were installed in parallel to compare two different types of pre-treatments before the RO units.
The treatments tested were:
- solids filtration;
- anaerobic treatment (UASB/EGSB);
- aerobic treatment (activated sludge / membrane bioreactor);
- ultra-filtration (pressurised hollow-fibre);
- reverse osmosis.
These trials had the objective of increasing effluent reclamation and substituting fresh water in this paper mill. The main results in AQUAFIT4USE were the following. Anaerobic treatment was able to remove 50 % and 70 % of the initial COD and BOD5, respectively, in both pilot plants, even though the presence of sulphates in the effluent is high in relation to COD values. Furthermore, these treatments produced enough biogas to be considered as cost-effective (valuated at EUR 700 000/year).
As part of the (biodegradable) COD and BOD5 was not removed in the anaerobic step, the aerobic stage was necessary before feeding the membrane treatments. COD and BOD5 removals were acceptable after the aerobic treatment to further perform a posterior membrane treatment. Although both pilot plants showed similar organic and sulphate removal rates, the pilot plant which holds the MBR treatment, showed a more stable operation behaviour regarding the removal of organics and fouling, but it was more expensive in terms of energy consumption.
Case studies - Chemical sector
The pilot work with the chemical industry focused on three major aspects:
- the application of membrane bioreactor technology (MBR) on variable and harsh chemical wastewater;
- piloting of various treatment trains for total effluent reuse;
- investigating technologies for trace organics removal combining valuable product recovery and local water reuse.
The tests were executed at two sites of BASF and Perstorp.
BASF
The integrated production site of BASF in Antwerp, Belgium, was considered a worst case scenario within the BASF-group to evaluate MBR process stability for total effluent treatment because it combines 54 production units in 4 production sectors.
During 1 year, 3 different submerged MBR pilots were tested in a set-up consisting of membrane filtration tanks coupled directly to the full-scale aeration basin, thereby taking into account site specific constraints. The three selected technologies represented different membrane module configurations and different membrane materials. It was concluded that membrane separation of mixed liquor from the BASF Antwerp treatment plant was technically feasible at flux ranges of 8 - 20 l/m².h. However, membrane permeability was clearly influenced by wastewater composition, with several simultaneous upsets in all pilot units. More scaling and fouling was observed than originally expected and this caused the need of frequent cleanings. In addition to the rather high cleaning frequency, membrane recoveries were sometimes unpredictable. The test results thus underachieved the expectations for a stable and reliable long-term full-scale application at the BASF Antwerp site.
Perstorp
The second test site was Perstorp Specialty Chemicals AB in Sweden. Here, various treatment trains were assessed in view of total effluent reuse. Emphasis was put on the possibility to find the minimum water quality fit-for-use for cooling purposes and other reuse options for low grade water quality, while keeping good cooling or process water practise by reducing the biofouling and hygienic risks. The tested treatment trains included MBR, RO, Denutritor and AOP technology in various combinations.
Case studies - Food sector
In the food industry the main points of attention in relation to sustainable water use and closing the water cycle are health and safety. Therefore, for this sector the focus was on applications where no extra risks for health and safety are introduced. This includes alternative water sources for application in no-direct contact with the product and the application of new technologies for the production of process and product water from existing and safe water sources.
Denutritor for reduction of micro-organisms in rain water
Unilever Ben & Jerry's ice-cream factory in the Netherlands is aiming at the reuse of collected rainwater to minimize the amount of drinking water in their production. This rainwater can be used for cleaning of packing and transport material (containers, pallets, etc.) and for sanitation (toilets) at the plant location. Denutritor can potentially improve the microbial quality of stored rainwater, by reducing the amount of available nutrients in the water and thus minimizing the microbial growth and biofilm formation.
Biofouling potential was reduced with 72 % and the AOC content in the rainwater was depleted to concentrations below 10 μg AOC/l.
Besides the pilot tests indicated that by Denutritor treatment risk for accumulation of pathogens in the rainwater reservoir tank was reduced, and combined with relatively low doses of UV, collected rainwater can be safely applied for sanitation purpose in food industry.
UF for effluent treatment for cooling water preparation
The application of ultrafiltration for polishing a tertiary effluent stream from the biological waste water treatment was successfully tested at the soy factory of ALPRO in Wevelgem to upgrade the biological effluent for make-up water in cooling water systems. Based on the results of the pilot test it was recommended to perform the UF filtration at a gross flux of 17 l/m².h, in presence of 1 ml/min iron dosing.
To have an indication of the suitability for use as RO feed, the potential for RO membrane fouling was evaluated and compared with sand filtration. Breakthroughs of suspended solids were sometimes detected for the sand filtration, while these did not occur in the ultrafiltration effluent.
FACT for softening of drinking water
A series of FACT pilot test trials was carried out at ALPRO in Belgium for softening city water from three sources, with average calcium concentration of 116 mg/l.
During the pilot tests at Alpro, it was shown that hardness can be reduced by 80 % and the final calcium concentration in the softened water is circa 20 mg/l calcium. The residual calcium concentration is limited by the dissolved carbonate present in city water. Lower calcium concentrations are obtainable by adding extra soda to the city water.
Evaluation of different filter media for the removal of specific chemical compounds
To evaluate the efficiency of different filter media for the removal of specific chemical compounds in bottled water industry, laboratory and pilot tests have been carried out with different technologies, based on adsorption and ion exchange. The focus was on arsenic, boron and bromide.
The results of the pilot tests have proven that titanium-dioxide based media are an efficient selective treatment for arsenic removal with very high adsorption capacity. TiO2 is a non-regenerative media, similar to granular ferric hydroxide-based media but with higher adsorption capacity. This treatment does not consume chemicals for regeneration and water losses are therefore very limited: 21 g Fe(OH)3/m3 versus 8 g TiO2/m3 treated water.
No significant impact on water quality except during the 1st days after start-up of the pilot was observed.
The main results from the test for boron removal with a strong basic anion exchanger are:
- Boron removal efficiency was high, from 7.5 mg B/L to less than 25μg B/L.
- The impact of the ion exchanger on water composition does not allow a treatment of natural mineral and spring waters, but other applications, with less critical quality demands than these types of waters are possible.
- Water loss estimations are comparable to those of reverse osmosis.
- Ion exchange technology requires less energy than reverse osmosis but chemicals consumption is important.
Case studies - Textile sector
The textile finishing companies Tekstina, Svilanit and Inotex do not implement any water reuse in 2012. Fresh and high quality water is used in all the production processes, usually after softening. All the water used in the production, except for the amount that is lost (mainly evaporation), is collected through the wastewater network and, after neutralisation, sent to the municipal WWTP. Wastewater includes: cleaning water, process water, cooling water and storm water. The amount of water used varies widely, depending on the specific process operated at the mill, the equipment used and the prevailing management approach regarding water use.
The 'Manual for the characterisation of textile small to medium-sized enterprises (SMEs)' (PIDACS) was issued and used in Tekstina, Svilanit and Inotex production characterisation. The document was aimed at guiding partners in the data collection procedure providing a systematic factory investigation and production processes characterisation. In such a way, a detailed analysis, containing all the relevant process data for further elaboration of a comprehensive mapping of all processes related to water use was obtained.
Water reuse network design
Different reuse network scenarios were designed on the basis of existing water and wastewater network analysis, from the effluents characterisation and through water and contaminants balances calculations. Scenarios are based either on machinery separation or on effluents separation based on continuous monitoring of the effluents characteristics. In these scenarios, wastewater treatment technologies evaluated were different combinations of UF, NF, AOP, MBR and evapoconcentration. For Tekstina, the most relevant reuse scenario based on machinery separation while for Svilanit based on monitoring separation.
Pilot testing of proposed reuse schemes
In Svilanit, the waste stream separation was based on the monitoring of relevant parameters mainly due to the polyvalent application of different textile processes in the same equipment. The majority of the wastewater is low concentrated (approximately 60 %) and treatable by conventional membrane technologies like UF, NF. For Svilanit the treatment train composed of UF and NF or UF and AOP has been verified to be effective enough to meet water reuse criteria. Moreover, for specific very low concentrated streams (e.g. the last fabric rinsing) only UF or AOP as standalone treatment technology were sufficient to provide reusable water. Estimated investment costs for the treatment train composed of UF and NF amounted to EUR 230 000 and operation costs EUR 18 000/a.
Cross-sector benefits: real-life experiences in four sectors
One of the important overall objectives of the project was the search for cross-sector benefits. Technologies, management strategies applied in one sector could be beneficial in other sectors as well. Instead of developing separate routes in each sector, it is also good to look for synergies between the sectors. Although specifically designed for one sector, some measures could also be of interest for other sectors. The starting point for this work was the study of 4 cases, one in each sector. Four companies were investigated and the water network was scrutinized. The goal was to characterize, analyse and compare the water networks in the four sectors and find benefits beyond the sector level. These benefits can be situated on different areas: the water network itself, process conditions of water treatment or other processes, optimisation strategies. The water networks of a paper mill (SAPPI), a food company (CHS), a textile company (Textina) and a chemical plant (Perstorp) were described and visualized. The visualized water network also immediately defines the scope of the optimisation. Each case was handled by a different partner to optimize. Hence, a comparison could be made in the way the optimisation problem was approached (the WESTforINDUSTRY tool was not used in the cases, as it was not available at that moment).
Potential impact:
During the development of AQUAFIT4USE, the expected general impact of the project was defined as follows: AQUAFIT4USE will contribute to strongly improved sustainable water use in industries, leading to:
- reinforcing the competitiveness of both the water consuming industry as the water technology suppliers;
- getting new market opportunities from the results of AQUAFIT4USE.
More specific impacts of sustainable water use on resource efficiency, product and processes are listed below:
- Substantial reduction of fresh water needs and more efficient use of limited water resources in European Industries for the four sectors with the highest water demand by integrated water resources management, also by:
- new cross-sectorial technologies and other solutions and the implementation of the integrated process technologies in the four industrial sectors;
- substantial reduction of effluent discharges to mitigate the environmental impact of water use and water treatment, by new technologies with higher recovery and/or lower wastes and by-products and a better process integration;
- better management of health and safety risks in water use by new technologies, monitoring systems and water management tools;
- improved process stability and product quality by improved and more constant water quality.
After more than four years of research, it can be concluded that on both the general level and on the more specific topics AQUAFIT4USE has had a great impact on industrial water use. Besides the development of technological solutions for the main challenges, the dissemination and training activities played an important role to come to these achievements.
General impact
The main overall result of AQUAFIT4USE is that it showed that closing the water cycle (by reuse of water) and the use of water sources other than drinking water can be done on a safe and reliable way for several industrial sectors. AQUAFIT4USE showed this very convincing by setting-up pilot testing and treatment trains. The project showed it not only to its project partners but also to the broad outside world, thereby opening doors for the realisation of future demonstration projects.
AQUAFIT4USE realised that, in order to bring about this change in the water use paradigm in the different industrial sectors, it is very important to create more awareness. First of all about value and importance of water for industries, but also about questions like:
- Where is the sector not sustainable in relation to water use and emissions?
- What kind of solutions are available?
- Which solutions have other sectors available?
- What are the real bottlenecks.
Specific impact on water use, process and product
Water (re)-use
The improved insight of the participating water using industries in their water use and the opportunities will lead to a reduction of the use of fresh drinking water of 30 % in the coming years. This decrease in the use of water will differ by sector as some sectors (like the paper one) did already close their water cycle to a great extent; for others, however, a more or less complete closure of the water cycle is possible in future, leading to a higher reduction. To give some figures from the participating partners, one paper company reduced their water and energy use with 15 - 20 % thanks to the better insight in his water system, a second paper industry changed to 100 % use of reclaimed water. One of the textile partners made plans to go to a far going closure of the water cycle. For one of the chemical industries, the reuse of effluent will lead to a reduction of water use of over 20 %.
Mitigate environmental impact
The environmental impacts of the project are focused on the following:
- Reduction of (high quality) water use and the use of other water sources. This is a result of the above mentioned water reuse and closure of the water cycle.
- Reduction of effluent discharge. The focus in AQUAFIT4USE was not on end-of-pipe treatment but water reuse, which leads to a reduction of the volume finally discharged. A disadvantage of this approach is that the concentration of pollutants or problematic species is increased (see also next point). For one company replacing the ion exchange softening by a crystallisation process, the amount of salts discharged (from the regeneration) reduced with over 90 %.
- Concentrates and brines. Closure of the water cycle often leads to more concentrated streams that cannot be discharged. By the development of new desalination technologies like flow through capacitor and improved evapo-concentration the volume of brines will decrease and possibly the regain of raw materials can be improved.
- Less energy and chemicals use. The reuse of warm and/or cold water will lead to a reduction of the energy needed by 20 to over 50 %. Besides, scaling prevention has a great impact at the functioning of heating and cooling systems. The development of new biofouling and scaling prevention technologies have reduce the use of water conditioning chemicals both for utility water and in paper processing.
Better management of safety and health risks
The safety and health risks are reduced by the following:
- The development of a HACCP based water quality control methodology. An improved insight in health and safety risks of the water system is an important part of this tool.
- The development of new probes for faster analysing micro biological parameters.
- Improved disinfection technologies, like Denutritor and better insight in the effect of nano-silver.
The impact on this area is hard to measure, but is directly coupled with water reuse, and the use of other sources than drinking water, especially for the food industry. So the expected impact of AQUAFIT4USE on these topics is considerable.
Improving process stability and product quality
There is a very strong link between water quality and processes and product. For all industries, a better control of the water quality will lead to less production stops, less fall out of products and a better product quality. For food products, this is related to the above mentioned safety issues. For textile industry, it has been proven in different lab tests of dying of fabrics.
Contribution to standards
AQUAFIT4USE has also collaborated with other initiatives as in the case of the European Water Partnership.
As a response to Europe's water challenge of achieving Sustainable Water Management in Europe by 2030, according to the Water Vision for Europe, the European Water Partnership (EWP) initiated the Aquawareness programme as a strategy to move Europe towards a resource efficient and sustainable water culture, targeting political decision makers, key stakeholders and European citizens.
Societal implication
There were no specific ethical issues.
Over 200 persons were involved in the project, of which 40 % women, so no specific gender equality actions were needed. Remarkable is the high number of female PhD students. In the project, a lot of attention is paid to the high-level education especially at the universities.
Different disciplines are involved like engineering sciences, chemical sciences, mathematics, etc.
Socio-economic impact
The economic impact and the effect of AQUAFIT4USE on the competitiveness of both the water using industries and the suppliers is difficult to estimate but will in most cases be considerable.
For the end-users sustainable water use and closing the water cycle can lead to a substantial cost reduction. In general, the savings on the water costs itself will not be the most important part. For most industries, the costs for water intake are not more than a few percent of the total costs, but the water related cost can be plural. The saving of energy by reuse of warm water streams, reduction of losses of raw materials and lower discharge and treatment costs can result in a saving of five to over 25 % of the total production costs.
Dissemination and training
General
To create real impact a very active dissemination of the project findings and further transfer of the knowledge by training and exploitation activities is essential. Due to the strong applied character of the project the focus of the dissemination was on the industrial suppliers and end users, but also other stakeholders, like policy makers, researchers and students were informed about the results. The knowledge transfer was partly carried out inside the project, between the partners, and between the different sectors. This will be elaborated further below.
Types of activities
Different types of dissemination activities were performed, like oral communications at congresses and workshops, articles, scientific papers, posters, newsletter and the website.
Dissemination activities were classified in general and specific ones. The former are those aimed for a wide audience not having a deep knowledge on water science and technology. The topics of general dissemination activities could be specific developments of the project but these were then always presented in an accessible manner.
Dissemination activities
AQUAFIT4USE website: http://www.AQUAFIT4USE.eu
The AQUAFIT4USE project portal was set up from the beginning and upgraded several times in the course of the project. The website offers public access contents as well as a private section for AQUAFIT4USE partners. The public section is updated periodically with water related news and information on industrial water use events. The project newsletters are posted on the home page to enable easy access by the users. The AQUAFIT4USE website differs from other funded project websites in that the project portal offers a menu from which the visitor can download valuable scientific contents, such as the presentations given in the different congresses organised in the frame of the project as well as those articles considered publicly available.
AQUAFIT4USE newsletters (AquaFit4NEWS)
Given the light style in which they are written and the synthetic way of presenting the information, the AQUAFIT4USE newsletters denominated 'AquaFit4NEWS' were conceived as a key tool for the project consortium to communicate with the public, not only regarding the hard technical or scientific results achieved but also considering the social implications of the project. The consortium issued a total of 15 newsletters.
Congresses
Partners of AQUAFIT4USE have participated in a lot of congresses on different levels, from individual presentations of project results, the organisation of a special session in a congress to the organisation of two specific AQUAFIT4USE congresses, the midterm congress and the final congress. The latter two mentioned were the main events in which the visibility of the project was given a boost.
The AQUAFIT4USE midterm conference
The AQUAFIT4USE midterm conference took place in Oviedo (Spain) between 13 and 16 June 2010 and was organised in collaboration with the Integral Water Cycle: Present and Future, Seventh International Congress of ANQUE (Spanish National Association of Chemistry-related professionals). A total of 26 oral communications were given in the event presenting the results achieved till then, form the assessment of a sustainable water use in industry or the modelling of different water stages, to the application of advanced treatments and the results obtained in the project industrial cases.
The presentations were divided in four technical sessions:
Session 1 - Sustainable water management
Session 2 - Waste water treatments
Session 3 - Advanced treatments
Session 4 - Good examples of industrial cases
The AQUAFIT4USE end congress
The congress was celebrated in cooperation with the I-SUP Conference, that was held from 6 to 10 May 2012 in Bruges (Belgium). Since the I-SUP event focused on sustainability, it was considered the perfect platform to achieve a good visibility and audience for the AQUAFIT4USE end congress.
Papers and articles
Over 50 papers, articles and other news items were written and published in different types of Journals and magazines, both national and international.
The great majority of specific dissemination items is constituted by oral communications and related papers. The number of peer-reviewed scientific papers produced in the project was 19. This rather low number can be explained by the application focused research in the project.
Exploitation
The knowledge generated has helped the industries of the sectors considered in the project to improve their water systems either by reducing their fresh water consumption or by increasing the efficiency of their water related processes. This knowledge is in most of the cases not suitable for intellectual property protection. The following project results however, can be understood as complete, distinct blocks of knowledge and can be subject of clear commercial exploitation. For each one of the results below, a plan for exploitation, dissemination and training was prepared and updated in the course of the project:
- The water quality management tool (WESTforINDUSTRY)
- VIT-kits
- FACT
- CapDI
- Denutritor.
These exploitation, dissemination and training plans were used to support the developers in the next steps towards marketing of the results.
Training activities
From the project proposal phase, it was decided that training would be organised in three different levels, namely:
- Learning-from-each-other activities: These activities entail the transfer of knowledge, from one sector to another. The initial idea of transferring project generated knowledge was expanded to consider the transmission of any type of technical or scientific knowledge that especially the industrial partners may require. Through knowledge prospection, in total 46 learning-from-each-other sessions were organised in the course of the project, some of which were also open to audiences from outside the consortium.
- Lifelong learning activities: This type of training consisted mainly in updating the technical knowledge of the staff of industrial partners. The typical training scheme associated to this concept involved an research and technology development (RTD) performer training companies of its own sector. In some cases, training was also open to external companies of the same sector. At the end of the project, 19 lifelong learning had been carried out by the project partners.
- Education of young researchers: Education of young researchers was considered of crucial importance for the project, since they are the ones who will ensure that our project results generate a lasting value, enabling the transfer and consolidation of existing and newly acquired know-how in the organisations hosting them.
Special dissemination activities
The AQUAFIT4USE movie
With support of EC dissemination project STREAM a video was made of the project.
Project website: http://www.AQUAFIT4USE.eu
AQUAFIT4USE has brought innovative solutions to increase the sustainable use of water in industry in four important water intensive sectors: chemical, paper, textile and food.
By the development and piloting at industrial level of new, reliable cost-effective technologies, tools and methods, big steps have been made towards the sustainable use of water resulting in significant reduction of the fresh water needs, closing the water cycle, mitigation of the environmental impact and the production and use of water in accordance with the specifications of industry for the different processes and applications, 'water fit-for-use'. Supporting the industry to secure this vital resource and to decouple the water use and the related environmental impact from economic growth are important issues to support European Union (EU) policy on competitiveness, resource efficiency and environment.
Project context and objectives:
By consuming several billions m³ of water a year, European industry has a significant impact on available water sources. Legislation, stringent discharge standards, higher process and product demands and increasing water scarcity force industry to ensure higher water quality, resulting in higher costs.
'For the water consuming industry, water is no longer regarded as a commodity, consumable or utility but as a highly valuable resource, a vital element used in close conjunction with the production processes. Industries want to become more and more independent of public and private parties for the supply of process water and the treatment of wastewater. Furthermore, they want to use water qualities according to their own specifications, fit-for-use'.
This vision on sustainable water use and the great economic importance of water for the industrial sector was already defined in the first vision document and Strategic Research Agenda (SRA) of the European Water Platform (WTP) in 2006. In the updated SRA in 2011, more emphasis was put at water quality definition and water-fit-for-use, closure the water cycle and a more integrated approach.
Four pillars for sustainable water use in industry
AQUAFIT4USE is built on four pillars:
1. Water fit-for-use
Water fit-for-use is the basis of the project. In the current situation, most of the industries are not able to answer the question 'What water quality is really needed?' Knowledge on the effect of the water quality on process, product quality and health issues is not available. This makes that industries often choose for far better water qualities than needed. However, sustainable water use means: use water of right quality, 'fit-for-use'. AQUAFIT4USE gives not only an answer to the question 'What is the minimum water demand and water quality' that is really needed, but also to questions like:
- How can these water qualities be produced and maintained?
- How can these water qualities be monitored and controlled?
- What are the effects of using lower water quality?
These questions first need to be answered, before the industries can take further steps in sustainable water use, closing the water cycle and use of different water sources.
2. Integrated sustainable water use in industry
Sustainable water use requires an holistic approach. Within AQUAFIT4USE, there is a strong focus on the integration of all water related aspects, like new sources, energy, waste(s), process, product and environment. This is carried out in a systematic and structured approach, that ensures that all important mass and energy flows are taken into account, and scenarios for optimisation are developed including the use of process integration and energy and water pinch techniques. Environmental impact assessment is part of this approach.
3. Strong industrial participation
Within AQUAFIT4USE, 22 of the 34 partners are industries, 9 industrial suppliers and 13 end-users. The end-users, representing the four major European Union (EU) water consuming industries, paper, chemistry, food and textiles, were selected on their annual volume of water consumption and are complementary towards water research needs and know-how.
4. Cross-sectorial solutions
The four target industries are dealing partly with similar problems and challenges, but do have also their own specific questions. From previous European and national research projects, the developed knowledge can be summarized as follows:
Chemical industry: The focus in the past was on treatment of strongly polluted effluents; removal of trace elements; treatment of water, with emphasis on reuse in cooling systems, i.e. focus on corrosion problems and chemical conditioning. Water loop closure for other applications got limited attention.
Paper industry: A lot of effort is given to water saving and closing of water circuits, thereby substantially reducing the environmental impact; process modelling and automation and Kidney technologies as internal process water treatment are essential elements in this strategy. A number of problems around the removal of substances are not solved yet and further closing the water cycle causes new problems. As still some 2 billion cubic meter of fresh water is currently used, there is still a challenge.
Food industry: The main point of attention is water quality in relation to product quality and health. Therefore water reuse is only implemented to a limited extent. Besides, water treatment measuring and monitoring is a major concern.
Textile industry: It pays already a lot of attention to sustainable water use. Because most textile companies are small and medium-sized entreprises (SMEs), handling small orders, the composition of water streams is highly variable and therefore often a problem.
Objectives
The overall objective of AQUAFIT4USE is the development of new, reliable, cost-effective technologies, tools and methods for sustainable water supply, use and discharge in the main European water consuming industries in order to:
- reduce high quality water consumption and fresh water needs;
- mitigate environmental impact;
- produce and apply water qualities in accordance with industrial own specifications (fit - for - use) from all possible sources;
- contribute to a far-going closure of the water cycle while;
- reducing water relating costs (intake, treatment, re-use, closed loops, discharge);
- improving product quality and process stability;
- increase independency and flexibility;
- better management of health and safety risks relating to water use.
This overall objective resulted in the following science and technology(S&T) objectives:
Objective 1: Water quality definition for processes, utilities and environment
As mentioned before, a good insight in the existing water system and especially in the water quality demands are basic requirements for sustainable industrial water systems. A systematic generic approach for the definition of the specific water quality demands (methodology) should be developed. Additionally, a detailed definition of specific water quality demands in the various industrial process steps of the four sectors is needed, as well as cross-sectorial parameter definition on scaling, biofouling, safety and health.
Objective 2: Integrated modelling and control of industrial water systems
Models of water treatment technologies and the various process steps (unit-process models) are the building blocks for modelling total water industrial systems, with the support of a newly developed Integrated water modelling methodology. The final model will be used in the case studies for simulation and optimisation. Also insight needs to be gathered in uncertainty and risks associated to alternative the water systems.
Objective 3: Practicable innovation in water treatment technologies
The development of new water treatment concepts and technologies is from the main technological objective of AQUAFIT4USE. The focus was on two levels:
- the development of new technologies to solve specific problems in the area of selective removal of specific substances, biofouling and scaling prevention, improved disinfection, desalination;
- the development and testing of different treatment concepts in practice. Combination of several treatment technologies (treatment trains) are needed to find solutions for the complex water issues and to produce water 'fit-for-use'.
Objective 4: integration and validation of solutions:
The interaction with other water-related issues, like process stability, product quality and energy and wastes, is regarded in more detail. Validation of the solutions, also using methodologies for environmental assessment are part of this objective.
Project results:
AQUAFIT4USE has brought about a lot of innovative and applicable results, that were very helpful to convince industries in different sectors on the feasibility of sustainable water use in their specific situation. Real steps forward have been made, giving answers to the main challenges of sustainable water use and finding solutions for the reuse of water, further closing of the water cycle and using alternative water sources without making concessions to product quality, health and safety.
In AQUAFIT4USE three types of results can be distinguished:
1. Solutions to improve water management
In this area a broad list of results can be mentioned: tools for simulation and optimisation of water systems, models, knowledge on water quality demands for processes and other water applications, measuring and monitoring equipment and assessment tools. Within this framework also other water related issues and integration aspects were explored.
2. Technological solutions to solve common industrial problems
Specific technological problems and challenges that are common for different sectors have been addressed by developing new technologies and adapting existing technologies for the specific situation.
3. Treatment trains as custom made solutions
Existing and new technologies were combined leading to innovative solutions to improve the water systems of different industries. These solutions were tested at pilot scale at various industrial locations, leading to a lot of practical experience.
Water quality management: The key to sustainable water use
Sustainable water use in industry starts with a good insight in the industrial water system, with a strong emphasis on the water quality issues. Answers to the next questions should be provided:
- What is the water quality that is really needed in a process or other application?
- How can this water quality be produced and/or maintained?
- What will be the effect of using a different water source?
- How can we monitor and control the water quality?
Water quality management (WQM) methodology
For answering the above mentioned questions a systematic step-by-step approach has been developed, the WQM methodology. This methodology is coupled with newly developed software tool for industrial water management WESTforINDUSTRY.
The steps of the WQM methodology are listed below:
1. definition of existing water system (information gathering);
2. setting up the water network;
3. parameter selection, assessment and standardisation (water quality definition);
4. supplying WESTforINDUSTRY with input;
5. simulation of the water network;
6. optimisation of the water network;
7. output analysis and processing;
8. water quality control.
It is very important to determine the system boundaries in the system definition phase, deciding also at what level a water management project will be carried out and which parts of the system (factory, site) will be involved.
Water-fit-for-use
A procedure for water quality definition was developed, as part of WQM, to determine the actual water quality needed for a specific process or treatment step. Important steps are the selection of the relevant parameters, the parameter assessment and standardisation, all related to the five defined quality aspects: product quality, product safety, process water function, machinery and pipes and health and environment. Based on this procedure the water qualities for selected processes in the four sectors have been determined and summarised in public reports and in the data base of WESTforINDUSTRY.
Water quality control (WQC)
For water quality control a quality system for the complete water system was developed. The method uses the principles of HACCP, the quality system for safe food production that is applied for years in almost every Food company. For water quality control, the approach is extended with other quality issues, like product quality, process water function, and health and working conditions, all being part of the water quality definition.
Modelling in industrial water systems
The development of models and the verification / validation of these models on real scenarios provided by the industrial partners was very important for the availability of simulation tools able to reproduce the water circuits. A mathematical model library that reproduces the most relevant wastewater treatment technologies studied within the AQUAFIT4USE project and other treatment technologies has been developed. These treatment technologies compiled in the model library, are classified in three categories:
1) solid-liquid separation units such as membrane technologies, settlers and electrochemical separation processes;
2) biological units like activated sludge units and membrane bioreactors;
3) chemical processes like disinfection units, coagulation-flocculation processes.
WESTforINDUSTRY: A software tool for model based optimisation of water systems
Description of the tool
In WESTforINDUSTRY knowledge about WQM, water treatment and modelling is brought together in a model-based software framework. The tool allows for defining, simulating (including various forms of graphical visualisation) and optimizing industrial water networks in a very intuitive way. The user is able to define the boundaries of the optimisation window by choosing the treatment technologies and the place where these technologies should be positioned. The software can then calculate the effect of each scenario and give a range of results which can be compared and evaluated based on different criteria (e.g. costs, fresh water use and discharge).
Tool development
A review of recent literature on industrial process modelling showed that the use of process integration tools has increased especially over the past two decades, and is mainly applied to focus on resource conservation, pollution prevention and energy management. Mathematical models to simulate industrial processes are used in a wide range of industrial sectors, but have especially emerged within industrial sectors with large scale production facilities, such as pulp and paper, petrochemical, synthetic chemical and pharmaceutical.
Testing and benchmarking WESTforINDUSTRY
Bench mark water network
The optimisation methodology proposed and implemented in the WESTforINDUSTRY software has been first verified and tested in the benchmark water network (BWN), that was defined in the scope of the project. The theoretical 'benchmark case-study' has been created to be used as a simple and common example of a water network subject to optimisation and that is assumed to contain the most important features typically found in industrial water networks. It has been successfully used as a common platform for discussion of water network visualisation, optimisation tools capability, process modelling methodology, needs for development of the simulation platform, cost analysis, optimisation methodology, etc.
Case studies with WESTforINDUSTRY
Holmen was used as a benchmark case. The information and the results obtained during the pilot trials were used for the development of mathematical models. These models, the data and the application of the WESTforINDUSTRY at Holmen's circuits were an important starting point for the future development of the tool.
Measuring and monitoring: Evaluation of sensors
To manage wastewater treatment processes in the industry, devices for measuring water quality parameters are needed. The choice of an instrument for a given process is not easy and is often made according to the basic metrological characteristics given by the suppliers. However these characteristics are not always sufficient and may even lead to a wrong choice: most suppliers do not take into account the real operating context with varying process conditions. This is why a procedure for the evaluation of sensors and analysers of water quality was developed.
Fast monitoring micro-organism: 145 new gene probes
As microbial growth and its relationship with health related issues is a key point in industrial water reuse policies, specific activities in this project were devoted to biofilm and corrosion detection methods and devices.
Another key aspect within the project was the assessment and definition of the actual microbiological water quality required for each process, as it is needed for the successful implementation of new treatment technologies for water reuse.
Together with the application of cultivation-based methods for microbial detection, a strong focus was given to the development of molecular methods based on Fluorescence in situ hybridisation (FISH) for microbial analysis in order to:
(i) describe various population communities completely and not only partial;
(ii) improve the current microbiological knowledge in the industries;
(iii) increase the speed of analysis in order to quickly evaluate newly implemented processes;
(iv) develop new tools to monitor micro-organisms which are process relevant, but difficult to cultivate or non-cultivable.
Holistic environmental assessments
To achieve the sustainability objective of this project, it was essential to check whether new technologies and reuse options allowed reducing environmental impacts of industrial water treatment. Two levels of scales are investigated. Firstly, the effect of water treatment processes on the actual toxicity of effluent was evaluated with the whole effluent assessment (WEA) methodology.
Technological solutions to solve industrial common problems
Water recycling and reuse present common concerns, independent from the industrial sector. These are biofouling, scaling, treatment of concentrate and saline streams, membranes management and processes to increase retention rate and limit membrane fouling, enhancement of bio-treatment, removal of COD and recalcitrant contaminants, effluent polishing for suspended solids removal and disinfection. The AQUAFIT4USE project proposed solutions that could be applied to solve these common problems.
The focus was on these specific topics to get a clear view on the advantages and bottlenecks of current processes and by trying to minimise the gap by new technological developments. On the basis of wastewater characterisation and definition of required water quality for each industry, different technologies and processes were tested and/or evaluated, in order to define the following:
- New treatment lines to obtain the water quality target, considering cost effectiveness, reliability, minimisation in waste and concentrate production. These new treatment lines are focused more particularly on internal recycling.
- New technologies that could be included in these treatment lines.
Most of these studies constituted preliminaries for pilot trials at location.
Biofouling and scaling prevention technologies
In the area of biofouling and scaling prevention AQUAFIT4USE focussed on three technologies: Denutritor, Nanosilver and FACT.
Denutritor - a biofiltration based biofouling prevention technology - was successfully tested at the effluent of the waste water treatment plant (WWTP) of a chemical plant in Sweden, resulting in an about eight-fold reduction of the biofouling potential, increasing the possibilities of reuse of the water for cooling and other industrial applications.
Denutritor was also tested at the Ben&Jerry's ice cream factory for the removal of (pathogenic) micro-organisms from rain water. It showed that Denutritor can reduce but not fully remove coliforms, E. coli and pathogenic bacteria present in collected rainwater. The amount of viable bacteria can additionally be reduced with 90 - 99 % efficiency by exposure to UV doses between 50 and 2500 J/L. During these laboratory tests, three new types of biofouling monitors were evaluated. The increase of protein concentration on the monitors appeared to be a good indicator of the biofouling potential of the synthetic WWTP effluent water tested. Biofouling monitors made from silicon or polyethylene (PE) tubes were finally selected for use during the further pilots.
Selective removal of substances
In a first part of the work, the potential of a new reductive technology was evaluated for the removal of brominated compounds and organic halides (AOX) in general. The reductive agent investigated was zerovalent iron (ZVI), which is extensively applied in groundwater treatment, but is an emerging technology for wastewater treatment.
Batch screening tests were performed for a broad range of wastewaters and ZVI types. For AOX, removal efficiencies were usually below 50 %, even at high iron concentrations. Removal efficiencies were best with nano-scale iron. For the removal of brominated compounds, efficiencies were on average higher than for AOX and reached up to 99 %.
Disinfection
The state-of-art study on innovative technology for the disinfection of industrial reused water and reclaimed water, showed that monochloramine has been found to be more effective than free chlorine in controlling biofilms and coliform bacteria in systems with long detention times due the lower decay rate of chloramine.
Innovative disinfection technologies are mostly physical technologies (pulsed electric field, radiofrequency power, ultrasound (US)) and photosensitisation of nano-particles(TiO2). They seem to be efficient against micro-organisms depending on many parameters.
Though they are not used a lot at this time to treat industrial water, these technologies can improve classical disinfection processes when used in association. The efficiency of US when used alone is not very high, but in association with other disinfection processes, US can be very interesting to reduce dosage or contact time.
There are only limited literature data on disinfection processes for industrial water reuse. Physical processes could be an interesting alternative to industries in order to reduce their chemicals consumption and to limit the by-product formation.
From above discussed experimental results, the following conclusions were stated:
- Spores of Bacillus subtilis are extremely resistant and no significant improvement in reduction of spores was observed with ultrasound treatment at low and high frequency.
- In comparison to ultrasound treatment of Bacillus subtilis spores, the reduction of E.coli is achieved in a very short treatment time.
- The higher the frequency, the better the inhibition efficiency for E.coli.
- The longer the treatment time, the better the inhibition efficiency for E.coli.
- The highest efficiency of inhibition was observed at 817 kHz for both 5 and 10 min.
- The treatment at 817 kHz and 5 minutes presents optimal conditions that allow a decrease of E.coli K12 concentration for 2.97 ± 0.58 log in demineralised water for the ultrasound equipment used in this study.
Saline streams
One of the objectives of AQUAFIT4USE was the development of new sustainable technologies for the treatment of saline streams. Three types of technologies have been considered:
a) Capacitive deionisation (CapDI)
In a CapDI system, salts are removed from the saline stream by the principle of capacitive deionisation.
Main results achieved are listed below:
- Developed modular CapDI system - A CapDI system based on unit modules has been developed that is now in production. Size of the system can be easily adjusted by installing more modules.
- Improved coated electrodes - Carbon coated electrodes showed to have excellent salt removal capacity, when compared to good quality commercial electrodes.
- Improved spacers: a low pressure drop spacer allows higher flow rates, resulting in the possibility to effectively treat a larger volume of water. This has been verified in the field.
- Improved membranes - PC cell is able to produce ion exchange membranes at significantly reduced cost compared to those of Tokuyama (the industry standard), without loss of desalination performance.
- Better understanding of performance relations for different types of water. It is beneficial to increase the total salt flux presented to the CapDI system, when the total amount of salt removed is of most interest. For cooling tower applications, where the salt concentration of the treated stream is very low, this means that the flow should be maximised.
- Use of constant current operation to enable energy re-use. More than 75 % of energy can be recovered at very low current densities. At practical conditions, more than 40 % of energy can be recovered.
- Experience of running a pilot system and full scale system on a cooling tower at two different sites.
- Knowledge on filtering requirements for pretreatment for CapDI for cooling tower application.
b) Membrane distillation-crystallisation (MDC) for highly concentrated saline streams
In MDC the salts are concentrated and crystallised by a membrane distillation process:
- Salt solutions can be concentrated up to saturation by membrane distillation (MD) without loss of specific flux (flux corrected for driving force).
- During crystallisation, a rapid flux decline is observed in the MD operation. It is expected that this is typically the case with salts like NaCl, but not with salts like CaCO3, because the lower temperature near the membrane due to temperature polarisation is favourable for this type of salts with an inverse solubility-temperature profile.
- Applying osmotic distillation (OD), a type of membrane distillation instead of MD gives a less sudden flux decline during crystallisation, but has to be optimised e.g. by adding seeds to prevent crystallisation on the membrane which still occurred in the experiments performed.
c) Evapoconcentration
Evapoconcentration is a technology commonly used to treat salty waste waters and results in relatively clean water (potentially suitable for reuse) and highly concentrated brine or precipitates. However, this technology is energy consuming and it is necessary to design / develop small scale units which are thermally optimised (way of evaporation and the heat recovery system), and use standardised compounds. The design must as well take into consideration the corrosion aspect. The objective of the work done was then to define such type of units for the treatment of industrial waste waters for the pulp and paper, textile and chemistry sector.
Use of micro-turbine:
- The combined heat and power concept with mechanical vapour recompression and a micro-turbine proved to be an interesting and energy efficient approach for evaporation.
- However, it could not be tested in practice because the chosen scale for demonstration was too small. Therefore, it was evaluated in a case study corresponding to landfill leachates treatment for which industrial data were available. Three different configurations were evaluated by calculations. For such an application (landfill leachates), the micro-turbine could be an interesting technology to produce heat and electricity from biogas.
Treatment trains as custom made solution - reliable and cost-effective
The objectives in this area was the identification of the best new (combinations of) water technologies to reduce environmental impacts by advanced closure of the water cycle and produce the required water quality for re-use. The work concerned the laboratory and preparations of pilot trials in the two industrial paper mills and two textile mills and case studies in all four sectors
Laboratory trials pulp and paper sector
In the pulp and paper industry a lot of effort is put into water saving and closing water circuits, also reducing substantially the environmental impact, both by process modelling and Kidney technologies as internal process water treatment. Kidney technology aims at removing specific substances from the recirculating process water. However, a number of problems around the removal of substances are not solved yet and further closing of the water cycle causes other problems.
Challenges for water reuse in the pulp and paper industry are the following:
- the elimination of residual (soluble) COD and BOD which can both affect the production process and the paper quality;
- the removal of sticky solids and suspended solids, which can induce plugging of pipes and showers, deposit formation, abrasion, loss of tensile strength;
- the treatment of concentrate streams containing calcium, sulphate, chloride and organics which can lead to salt accumulation in case of water loop closure, corrosion, scaling of pipes and showers in the paper production process.
The removal of calcium carbonate is crucial in the last case.
Therefore, there is a need to find new and reliable (combinations of) technologies to solve this challenges to achieve the water quality target for water re-use and which are tailored to suit product demands and standards.
Based on the waste water characterisation and the defined water quality requirements for paper mills, new treatment lines focused on internal recycling were defined to reach the water quality target including effectiveness, reliability and minimisation in waste and concentrate production.
The emphasis was on different key steps in the overall treatment train:
- Biological treatment: anaerobic processes and MBR;
- Filtration processes: 3FM high speed technology and nanofiltration;
- Tertiary treatments to reduce recalcitrant COD and scaling: advanced oxidation processes, coagulation, precipitation;
- Integration of processes (evapoconcentration, electrodialysis and softening) in the treatment line to treat the concentrate streams containing calcium, sulphate, chloride, organics, to minimize the waste production and enhance internal recycling.
Technologies were tested at lab scale on the wastewaters from two different paper mills: Hamburger Rieger (HRT), producing high quality coated and uncoated board from recycled paper and Holmen Paper Madrid (HOL), producing standard newsprint, improved newsprint (higher brightness) and lightweight coated paper (for magazines).
The most important findings for newsprint paper mills are the following:
- Anaerobic pre-treatment showed very good performance treating a low organic load wastewater as the effluent of a 100 % recycled NP/LWC paper mill, and assisting the aerobic stage on removing organics and sulphates; besides it produced enough biogas for being considered as cost-effective. Wastewater quality after biological treatment was suitable to perform a posterior membrane treatment.
- Membrane treatment by UF + RO is able to generate permeates of high water quality, fulfilling all the requirements for being used in critical points of the paper machine that require a very high water quality.
However, silica is a main issue for reuse as it leads to a reduction of recovery for RO treatment and scaling in UF treatment:
Different chemicals have been tested to achieve the silica removal efficiencies necessary to avoid silica scaling on RO membranes in the advanced treatment of the paper mill effluent: 80 - 90 % silica removal was achieved by coagulation at different pHs. Coagulation treatment can be as efficient as required (greater than 95 % removal), however, the costs are relatively high due to high dosages required and/or the use of complex chemicals.
Softening at high pH with the addition of magnesium compounds can also be used and efficient removal of silica is achieved down to the required values.
Further treatment of RO concentrates is needed for liquid discharge in municipal waste water to complain with the legislation. A further treatment is needed: Evapo-concentration is well adapted to treat membrane concentrates: the amount of final waste to be disposed is reduced and the produced water meets the water quality criteria for reuse in the paper production.
AOPs applied to membranes concentrates allow to reduce the recalcitrant COD, TOC and colour. The water can then be sent to the (closest municipal) WWTP.
In general:
- Ozone and AOPs were validated for both type of paper mills as final polishing treatment for water to be reused concerning disinfection, color removal, TOC and COD removal and biodegradability improvement.
Laboratory trials textile sector
The current situation reflects that the typical textile company prefers to use fresh high quality water in all production operations processes after softening to preserve the quality of their final products. Wastewaters are mostly discharged without any pre-treatments into the sewer, since sophisticated wastewater treatment technologies are mainly not affordable for small to medium-sized textile companies. Water reuse in the textile finishing industry needs the development of very specific processes (which can also be chosen among the already available ones) in order to produce the 'fit-for-use' water for a specific process (or a few processes).
Case studies: The proof of applicability
Paper sector
Based on laboratory work where a range of new and reliable (combinations of) technologies were evaluated, the most promising concepts have been scaled up successfully in different pilot trials. The focus has been on water quality targets for water reuse in-line with product demands and standards whilst avoiding any negative impact on paper machine runability and paper quality. As a result, customised pilot plant trains have been implemented.
Tests at Hamburger Rieger
Extensive tests involving seven simultaneously operated water treatment technologies were run at a German paper and board mill from February to September 2011. The dimensions of the trials were extraordinary in terms of both volume flows and the variety of treatment lines. Various processes could be operated in parallel as well as in series.
The technological and economic benefits of tailor-made water treatment lines have been investigated by comprehensive pilot trials. The trials were aimed at increasing the water reclamation rate of paper mills. Individually, each of the chosen treatment technologies represented the state-of-the-art in the paper industry in a particular case. By combining these advanced technologies to customised treatment trains, innovative research enabled breaking new ground in forward-looking water treatment.
The special composition of paper mill wastewaters calls for tailor-made treatment concepts. Consequently, the following main results have been derived:
- Water softening has been proven as an essential pre-treatment whenever membrane processes are to be used.
- Recirculation of nanofiltration concentrates in the anaerobic reactor after pre-treatment by ozone oxidation turned out to be unreliable in some cases.
- Using evapo-concentration for NF concentrate disposal has been evaluated as an alternative treatment technology.
- Two treatment lines including biological and physico-chemical processes have been proven to be technologically as well as economically viable:
(1) anaerobic treatment -greater than conventional activated sludge process - greater than softening - greater than pre-filtration - greater than nanofiltration - greater than evapo-concentration of concentrates;
(2) anaerobic treatment - greater than softening - greater than MBR - greater than nanofiltration - greater than evapo-concentration of concentrates.
Holmen
This paper mill, producing recycled paper from 100 % recovered paper, has optimised its water circuits for a longer period. Nowadays, they are consuming about 8 m3/T, which is lower than the estimated consumption in the BREF document for papers mills manufacturing newsprint paper. The required quality for any further closure of the circuits is very high, close to potable water quality.
% LDuring AQUAFIT4USE, after a deeper study of the current situation, two pilot plants with a capacity of 1 m3/h were installed in parallel to compare two different types of pre-treatments before the RO units.
The treatments tested were:
- solids filtration;
- anaerobic treatment (UASB/EGSB);
- aerobic treatment (activated sludge / membrane bioreactor);
- ultra-filtration (pressurised hollow-fibre);
- reverse osmosis.
These trials had the objective of increasing effluent reclamation and substituting fresh water in this paper mill. The main results in AQUAFIT4USE were the following. Anaerobic treatment was able to remove 50 % and 70 % of the initial COD and BOD5, respectively, in both pilot plants, even though the presence of sulphates in the effluent is high in relation to COD values. Furthermore, these treatments produced enough biogas to be considered as cost-effective (valuated at EUR 700 000/year).
As part of the (biodegradable) COD and BOD5 was not removed in the anaerobic step, the aerobic stage was necessary before feeding the membrane treatments. COD and BOD5 removals were acceptable after the aerobic treatment to further perform a posterior membrane treatment. Although both pilot plants showed similar organic and sulphate removal rates, the pilot plant which holds the MBR treatment, showed a more stable operation behaviour regarding the removal of organics and fouling, but it was more expensive in terms of energy consumption.
Case studies - Chemical sector
The pilot work with the chemical industry focused on three major aspects:
- the application of membrane bioreactor technology (MBR) on variable and harsh chemical wastewater;
- piloting of various treatment trains for total effluent reuse;
- investigating technologies for trace organics removal combining valuable product recovery and local water reuse.
The tests were executed at two sites of BASF and Perstorp.
BASF
The integrated production site of BASF in Antwerp, Belgium, was considered a worst case scenario within the BASF-group to evaluate MBR process stability for total effluent treatment because it combines 54 production units in 4 production sectors.
During 1 year, 3 different submerged MBR pilots were tested in a set-up consisting of membrane filtration tanks coupled directly to the full-scale aeration basin, thereby taking into account site specific constraints. The three selected technologies represented different membrane module configurations and different membrane materials. It was concluded that membrane separation of mixed liquor from the BASF Antwerp treatment plant was technically feasible at flux ranges of 8 - 20 l/m².h. However, membrane permeability was clearly influenced by wastewater composition, with several simultaneous upsets in all pilot units. More scaling and fouling was observed than originally expected and this caused the need of frequent cleanings. In addition to the rather high cleaning frequency, membrane recoveries were sometimes unpredictable. The test results thus underachieved the expectations for a stable and reliable long-term full-scale application at the BASF Antwerp site.
Perstorp
The second test site was Perstorp Specialty Chemicals AB in Sweden. Here, various treatment trains were assessed in view of total effluent reuse. Emphasis was put on the possibility to find the minimum water quality fit-for-use for cooling purposes and other reuse options for low grade water quality, while keeping good cooling or process water practise by reducing the biofouling and hygienic risks. The tested treatment trains included MBR, RO, Denutritor and AOP technology in various combinations.
Case studies - Food sector
In the food industry the main points of attention in relation to sustainable water use and closing the water cycle are health and safety. Therefore, for this sector the focus was on applications where no extra risks for health and safety are introduced. This includes alternative water sources for application in no-direct contact with the product and the application of new technologies for the production of process and product water from existing and safe water sources.
Denutritor for reduction of micro-organisms in rain water
Unilever Ben & Jerry's ice-cream factory in the Netherlands is aiming at the reuse of collected rainwater to minimize the amount of drinking water in their production. This rainwater can be used for cleaning of packing and transport material (containers, pallets, etc.) and for sanitation (toilets) at the plant location. Denutritor can potentially improve the microbial quality of stored rainwater, by reducing the amount of available nutrients in the water and thus minimizing the microbial growth and biofilm formation.
Biofouling potential was reduced with 72 % and the AOC content in the rainwater was depleted to concentrations below 10 μg AOC/l.
Besides the pilot tests indicated that by Denutritor treatment risk for accumulation of pathogens in the rainwater reservoir tank was reduced, and combined with relatively low doses of UV, collected rainwater can be safely applied for sanitation purpose in food industry.
UF for effluent treatment for cooling water preparation
The application of ultrafiltration for polishing a tertiary effluent stream from the biological waste water treatment was successfully tested at the soy factory of ALPRO in Wevelgem to upgrade the biological effluent for make-up water in cooling water systems. Based on the results of the pilot test it was recommended to perform the UF filtration at a gross flux of 17 l/m².h, in presence of 1 ml/min iron dosing.
To have an indication of the suitability for use as RO feed, the potential for RO membrane fouling was evaluated and compared with sand filtration. Breakthroughs of suspended solids were sometimes detected for the sand filtration, while these did not occur in the ultrafiltration effluent.
FACT for softening of drinking water
A series of FACT pilot test trials was carried out at ALPRO in Belgium for softening city water from three sources, with average calcium concentration of 116 mg/l.
During the pilot tests at Alpro, it was shown that hardness can be reduced by 80 % and the final calcium concentration in the softened water is circa 20 mg/l calcium. The residual calcium concentration is limited by the dissolved carbonate present in city water. Lower calcium concentrations are obtainable by adding extra soda to the city water.
Evaluation of different filter media for the removal of specific chemical compounds
To evaluate the efficiency of different filter media for the removal of specific chemical compounds in bottled water industry, laboratory and pilot tests have been carried out with different technologies, based on adsorption and ion exchange. The focus was on arsenic, boron and bromide.
The results of the pilot tests have proven that titanium-dioxide based media are an efficient selective treatment for arsenic removal with very high adsorption capacity. TiO2 is a non-regenerative media, similar to granular ferric hydroxide-based media but with higher adsorption capacity. This treatment does not consume chemicals for regeneration and water losses are therefore very limited: 21 g Fe(OH)3/m3 versus 8 g TiO2/m3 treated water.
No significant impact on water quality except during the 1st days after start-up of the pilot was observed.
The main results from the test for boron removal with a strong basic anion exchanger are:
- Boron removal efficiency was high, from 7.5 mg B/L to less than 25μg B/L.
- The impact of the ion exchanger on water composition does not allow a treatment of natural mineral and spring waters, but other applications, with less critical quality demands than these types of waters are possible.
- Water loss estimations are comparable to those of reverse osmosis.
- Ion exchange technology requires less energy than reverse osmosis but chemicals consumption is important.
Case studies - Textile sector
The textile finishing companies Tekstina, Svilanit and Inotex do not implement any water reuse in 2012. Fresh and high quality water is used in all the production processes, usually after softening. All the water used in the production, except for the amount that is lost (mainly evaporation), is collected through the wastewater network and, after neutralisation, sent to the municipal WWTP. Wastewater includes: cleaning water, process water, cooling water and storm water. The amount of water used varies widely, depending on the specific process operated at the mill, the equipment used and the prevailing management approach regarding water use.
The 'Manual for the characterisation of textile small to medium-sized enterprises (SMEs)' (PIDACS) was issued and used in Tekstina, Svilanit and Inotex production characterisation. The document was aimed at guiding partners in the data collection procedure providing a systematic factory investigation and production processes characterisation. In such a way, a detailed analysis, containing all the relevant process data for further elaboration of a comprehensive mapping of all processes related to water use was obtained.
Water reuse network design
Different reuse network scenarios were designed on the basis of existing water and wastewater network analysis, from the effluents characterisation and through water and contaminants balances calculations. Scenarios are based either on machinery separation or on effluents separation based on continuous monitoring of the effluents characteristics. In these scenarios, wastewater treatment technologies evaluated were different combinations of UF, NF, AOP, MBR and evapoconcentration. For Tekstina, the most relevant reuse scenario based on machinery separation while for Svilanit based on monitoring separation.
Pilot testing of proposed reuse schemes
In Svilanit, the waste stream separation was based on the monitoring of relevant parameters mainly due to the polyvalent application of different textile processes in the same equipment. The majority of the wastewater is low concentrated (approximately 60 %) and treatable by conventional membrane technologies like UF, NF. For Svilanit the treatment train composed of UF and NF or UF and AOP has been verified to be effective enough to meet water reuse criteria. Moreover, for specific very low concentrated streams (e.g. the last fabric rinsing) only UF or AOP as standalone treatment technology were sufficient to provide reusable water. Estimated investment costs for the treatment train composed of UF and NF amounted to EUR 230 000 and operation costs EUR 18 000/a.
Cross-sector benefits: real-life experiences in four sectors
One of the important overall objectives of the project was the search for cross-sector benefits. Technologies, management strategies applied in one sector could be beneficial in other sectors as well. Instead of developing separate routes in each sector, it is also good to look for synergies between the sectors. Although specifically designed for one sector, some measures could also be of interest for other sectors. The starting point for this work was the study of 4 cases, one in each sector. Four companies were investigated and the water network was scrutinized. The goal was to characterize, analyse and compare the water networks in the four sectors and find benefits beyond the sector level. These benefits can be situated on different areas: the water network itself, process conditions of water treatment or other processes, optimisation strategies. The water networks of a paper mill (SAPPI), a food company (CHS), a textile company (Textina) and a chemical plant (Perstorp) were described and visualized. The visualized water network also immediately defines the scope of the optimisation. Each case was handled by a different partner to optimize. Hence, a comparison could be made in the way the optimisation problem was approached (the WESTforINDUSTRY tool was not used in the cases, as it was not available at that moment).
Potential impact:
During the development of AQUAFIT4USE, the expected general impact of the project was defined as follows: AQUAFIT4USE will contribute to strongly improved sustainable water use in industries, leading to:
- reinforcing the competitiveness of both the water consuming industry as the water technology suppliers;
- getting new market opportunities from the results of AQUAFIT4USE.
More specific impacts of sustainable water use on resource efficiency, product and processes are listed below:
- Substantial reduction of fresh water needs and more efficient use of limited water resources in European Industries for the four sectors with the highest water demand by integrated water resources management, also by:
- new cross-sectorial technologies and other solutions and the implementation of the integrated process technologies in the four industrial sectors;
- substantial reduction of effluent discharges to mitigate the environmental impact of water use and water treatment, by new technologies with higher recovery and/or lower wastes and by-products and a better process integration;
- better management of health and safety risks in water use by new technologies, monitoring systems and water management tools;
- improved process stability and product quality by improved and more constant water quality.
After more than four years of research, it can be concluded that on both the general level and on the more specific topics AQUAFIT4USE has had a great impact on industrial water use. Besides the development of technological solutions for the main challenges, the dissemination and training activities played an important role to come to these achievements.
General impact
The main overall result of AQUAFIT4USE is that it showed that closing the water cycle (by reuse of water) and the use of water sources other than drinking water can be done on a safe and reliable way for several industrial sectors. AQUAFIT4USE showed this very convincing by setting-up pilot testing and treatment trains. The project showed it not only to its project partners but also to the broad outside world, thereby opening doors for the realisation of future demonstration projects.
AQUAFIT4USE realised that, in order to bring about this change in the water use paradigm in the different industrial sectors, it is very important to create more awareness. First of all about value and importance of water for industries, but also about questions like:
- Where is the sector not sustainable in relation to water use and emissions?
- What kind of solutions are available?
- Which solutions have other sectors available?
- What are the real bottlenecks.
Specific impact on water use, process and product
Water (re)-use
The improved insight of the participating water using industries in their water use and the opportunities will lead to a reduction of the use of fresh drinking water of 30 % in the coming years. This decrease in the use of water will differ by sector as some sectors (like the paper one) did already close their water cycle to a great extent; for others, however, a more or less complete closure of the water cycle is possible in future, leading to a higher reduction. To give some figures from the participating partners, one paper company reduced their water and energy use with 15 - 20 % thanks to the better insight in his water system, a second paper industry changed to 100 % use of reclaimed water. One of the textile partners made plans to go to a far going closure of the water cycle. For one of the chemical industries, the reuse of effluent will lead to a reduction of water use of over 20 %.
Mitigate environmental impact
The environmental impacts of the project are focused on the following:
- Reduction of (high quality) water use and the use of other water sources. This is a result of the above mentioned water reuse and closure of the water cycle.
- Reduction of effluent discharge. The focus in AQUAFIT4USE was not on end-of-pipe treatment but water reuse, which leads to a reduction of the volume finally discharged. A disadvantage of this approach is that the concentration of pollutants or problematic species is increased (see also next point). For one company replacing the ion exchange softening by a crystallisation process, the amount of salts discharged (from the regeneration) reduced with over 90 %.
- Concentrates and brines. Closure of the water cycle often leads to more concentrated streams that cannot be discharged. By the development of new desalination technologies like flow through capacitor and improved evapo-concentration the volume of brines will decrease and possibly the regain of raw materials can be improved.
- Less energy and chemicals use. The reuse of warm and/or cold water will lead to a reduction of the energy needed by 20 to over 50 %. Besides, scaling prevention has a great impact at the functioning of heating and cooling systems. The development of new biofouling and scaling prevention technologies have reduce the use of water conditioning chemicals both for utility water and in paper processing.
Better management of safety and health risks
The safety and health risks are reduced by the following:
- The development of a HACCP based water quality control methodology. An improved insight in health and safety risks of the water system is an important part of this tool.
- The development of new probes for faster analysing micro biological parameters.
- Improved disinfection technologies, like Denutritor and better insight in the effect of nano-silver.
The impact on this area is hard to measure, but is directly coupled with water reuse, and the use of other sources than drinking water, especially for the food industry. So the expected impact of AQUAFIT4USE on these topics is considerable.
Improving process stability and product quality
There is a very strong link between water quality and processes and product. For all industries, a better control of the water quality will lead to less production stops, less fall out of products and a better product quality. For food products, this is related to the above mentioned safety issues. For textile industry, it has been proven in different lab tests of dying of fabrics.
Contribution to standards
AQUAFIT4USE has also collaborated with other initiatives as in the case of the European Water Partnership.
As a response to Europe's water challenge of achieving Sustainable Water Management in Europe by 2030, according to the Water Vision for Europe, the European Water Partnership (EWP) initiated the Aquawareness programme as a strategy to move Europe towards a resource efficient and sustainable water culture, targeting political decision makers, key stakeholders and European citizens.
Societal implication
There were no specific ethical issues.
Over 200 persons were involved in the project, of which 40 % women, so no specific gender equality actions were needed. Remarkable is the high number of female PhD students. In the project, a lot of attention is paid to the high-level education especially at the universities.
Different disciplines are involved like engineering sciences, chemical sciences, mathematics, etc.
Socio-economic impact
The economic impact and the effect of AQUAFIT4USE on the competitiveness of both the water using industries and the suppliers is difficult to estimate but will in most cases be considerable.
For the end-users sustainable water use and closing the water cycle can lead to a substantial cost reduction. In general, the savings on the water costs itself will not be the most important part. For most industries, the costs for water intake are not more than a few percent of the total costs, but the water related cost can be plural. The saving of energy by reuse of warm water streams, reduction of losses of raw materials and lower discharge and treatment costs can result in a saving of five to over 25 % of the total production costs.
Dissemination and training
General
To create real impact a very active dissemination of the project findings and further transfer of the knowledge by training and exploitation activities is essential. Due to the strong applied character of the project the focus of the dissemination was on the industrial suppliers and end users, but also other stakeholders, like policy makers, researchers and students were informed about the results. The knowledge transfer was partly carried out inside the project, between the partners, and between the different sectors. This will be elaborated further below.
Types of activities
Different types of dissemination activities were performed, like oral communications at congresses and workshops, articles, scientific papers, posters, newsletter and the website.
Dissemination activities were classified in general and specific ones. The former are those aimed for a wide audience not having a deep knowledge on water science and technology. The topics of general dissemination activities could be specific developments of the project but these were then always presented in an accessible manner.
Dissemination activities
AQUAFIT4USE website: http://www.AQUAFIT4USE.eu
The AQUAFIT4USE project portal was set up from the beginning and upgraded several times in the course of the project. The website offers public access contents as well as a private section for AQUAFIT4USE partners. The public section is updated periodically with water related news and information on industrial water use events. The project newsletters are posted on the home page to enable easy access by the users. The AQUAFIT4USE website differs from other funded project websites in that the project portal offers a menu from which the visitor can download valuable scientific contents, such as the presentations given in the different congresses organised in the frame of the project as well as those articles considered publicly available.
AQUAFIT4USE newsletters (AquaFit4NEWS)
Given the light style in which they are written and the synthetic way of presenting the information, the AQUAFIT4USE newsletters denominated 'AquaFit4NEWS' were conceived as a key tool for the project consortium to communicate with the public, not only regarding the hard technical or scientific results achieved but also considering the social implications of the project. The consortium issued a total of 15 newsletters.
Congresses
Partners of AQUAFIT4USE have participated in a lot of congresses on different levels, from individual presentations of project results, the organisation of a special session in a congress to the organisation of two specific AQUAFIT4USE congresses, the midterm congress and the final congress. The latter two mentioned were the main events in which the visibility of the project was given a boost.
The AQUAFIT4USE midterm conference
The AQUAFIT4USE midterm conference took place in Oviedo (Spain) between 13 and 16 June 2010 and was organised in collaboration with the Integral Water Cycle: Present and Future, Seventh International Congress of ANQUE (Spanish National Association of Chemistry-related professionals). A total of 26 oral communications were given in the event presenting the results achieved till then, form the assessment of a sustainable water use in industry or the modelling of different water stages, to the application of advanced treatments and the results obtained in the project industrial cases.
The presentations were divided in four technical sessions:
Session 1 - Sustainable water management
Session 2 - Waste water treatments
Session 3 - Advanced treatments
Session 4 - Good examples of industrial cases
The AQUAFIT4USE end congress
The congress was celebrated in cooperation with the I-SUP Conference, that was held from 6 to 10 May 2012 in Bruges (Belgium). Since the I-SUP event focused on sustainability, it was considered the perfect platform to achieve a good visibility and audience for the AQUAFIT4USE end congress.
Papers and articles
Over 50 papers, articles and other news items were written and published in different types of Journals and magazines, both national and international.
The great majority of specific dissemination items is constituted by oral communications and related papers. The number of peer-reviewed scientific papers produced in the project was 19. This rather low number can be explained by the application focused research in the project.
Exploitation
The knowledge generated has helped the industries of the sectors considered in the project to improve their water systems either by reducing their fresh water consumption or by increasing the efficiency of their water related processes. This knowledge is in most of the cases not suitable for intellectual property protection. The following project results however, can be understood as complete, distinct blocks of knowledge and can be subject of clear commercial exploitation. For each one of the results below, a plan for exploitation, dissemination and training was prepared and updated in the course of the project:
- The water quality management tool (WESTforINDUSTRY)
- VIT-kits
- FACT
- CapDI
- Denutritor.
These exploitation, dissemination and training plans were used to support the developers in the next steps towards marketing of the results.
Training activities
From the project proposal phase, it was decided that training would be organised in three different levels, namely:
- Learning-from-each-other activities: These activities entail the transfer of knowledge, from one sector to another. The initial idea of transferring project generated knowledge was expanded to consider the transmission of any type of technical or scientific knowledge that especially the industrial partners may require. Through knowledge prospection, in total 46 learning-from-each-other sessions were organised in the course of the project, some of which were also open to audiences from outside the consortium.
- Lifelong learning activities: This type of training consisted mainly in updating the technical knowledge of the staff of industrial partners. The typical training scheme associated to this concept involved an research and technology development (RTD) performer training companies of its own sector. In some cases, training was also open to external companies of the same sector. At the end of the project, 19 lifelong learning had been carried out by the project partners.
- Education of young researchers: Education of young researchers was considered of crucial importance for the project, since they are the ones who will ensure that our project results generate a lasting value, enabling the transfer and consolidation of existing and newly acquired know-how in the organisations hosting them.
Special dissemination activities
The AQUAFIT4USE movie
With support of EC dissemination project STREAM a video was made of the project.
Project website: http://www.AQUAFIT4USE.eu