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Membrane fouling problem is one of the most crucial issues which restricts the development of MBR and is, therefore, the prime research topic for many researchers worldwide. Anaerobic MBRs offer interesting perspectives as a potential solution for the treatment of wastewaters under extreme conditions, e.g. high temperature and/or high salt content, However, the research on membrane fouling of AnMBR system is still limited. Therefore, in this Master Thesis the research is focused on the flux determining conditions of AnMBR systems in hyper saline environment. Hyper saline environment is those containing salt concentration in excess of seawater which is 35g/l. The conditions of AnMBR in hyper saline environment are quite different from aerobic MBR system, so the measures applied in aerobic MBRs to prevent membrane fouling may not be useful in AnMBRs in hyper saline environment. In the first series of experiments of this thesis work, the efficiency of existing measures, which are applied in full-scale aerobic MBRs to prevent membrane fouling, are evaluated for application in AnMBRs under hyper saline conditions. Because the concentration of NaCl in hyper saline wastewater is quite high and NaCl can be used as flocculant (Mietta et al., 2009), one of the experiments was designed to induce proper shear force to the AnMBR reactor to test whether this manner could alleviate membrane fouling. Unfortunately, the result of this experiment was negative and membrane fouling was still serious. Then LCFA was added to the reactor to check its short-term effect on alleviating membrane fouling (Stumm and Morgan, 1995). The result showed that LCFA could not reduce membrane fouling within short time. Because the results of these measures in alleviating membrane fouling in AnMBR in hyper saline environment were not satisfactory, the second series of experiments of this thesis work were designed to analyse the foulant constituents of AnMBRs in hyper saline environment and their characteristics. The results of the second series experiments showed that sodium, calcium, iron and potassium were the main metal ions in cake layer. Likely, ion-exchange activities between calcium ions in the cake layer and sodium ions in the liquid phase were apparent under the hyper saline conditions in lab-scale AnMBR experiment. The functional groups of organic foulants on the fouled membrane were alkanes, carboxylic acid, nitro compounds, alkyl halides and alkenes in this research and chemical cleaning could only remove part of organic foulants.

Research performed of the last decades in the waste water treatment field has shown the ability of zeolites to adsorb ammonium via ion-exchange. Recent research has proven that zeolites might also be capable to remove the lower concentrations of ammonium present in groundwater to the for drinking water required standards. This makes it a promising technique as replacement for the traditional biological treatment. Still there is not much known about the effect of multiple regenerations with the different types of regenerant on the adsorption capacity and the durability of the zeolites. This research focuses on the chemical regeneration of zeolites which have been used to remove ammonium from anaerobic groundwater. The main goals hereby have been: - The determination of the effect of multiple regeneration on the ion -exchange capacity of the zeolites - The testing of the effectiveness of two types of regenerant: NaOH and NaCl - To see whether it is possible to reduce the amount of chemicals used for regeneration by reusing the regenerant. Because the adsorption experiments have been done with anaerobic water, an extra objective has been to investigate whether ammonium adsorption is hindered by the presence of Fe2+. A 4 column set-up has been designed in which two types of zeolite, clinoptilolite and aqualite, have been used. At a drinking water treatment plant a side stream of the influent of their rapid sand filters was used as influent for the columns. Two columns (one of each material) have been regenerated with 0,1 M NaOH, the other two with 1,8 M NaCl that was being recirculated.By monitoring the influent and effluent concentration of both ammonia and Fe2+, breakthrough curves could be determined. By comparing these, the impact of the regenerations on the adsorption capacity could be established. Extensive analyses of the used regenerant showed which ions were affected by regeneration and how much regenerant was actually used per regeneration. In the end the zeolites have been loaded and regenerated 11 times. The NaCl also has been used 11 times. Hereby it has been determined that the zeolites do loose some of their ion-exchange capacity by regeneration. This loss is the biggest after the first regeneration. After that the adsorption capacity fluctuates around 80% (NaOH) and 70% (reused NaCl) of it original capacity. The fluctuations are caused by changing lengths of the adsorption phase while the regeneration period stays constant. The reused NaCl shows a higher loss in capacity than the NaOH in combination with a higher chemical usage. From economical point of view NaOH is more feasible. The effect of the extreme pH on the zeolites has not been investigated though. It has been possible to reuse the regenerant and still obtain reasonable results. Whether that really is a reduction of the used chemicals, is not completely clear because no comparative study with single use NaCl has been performed. There has been no evidence that the presence of Fe2+ in the source water interferes with the ammonium adsorption. The positive effect that was found is that the iron is removed by the zeolites to great extent as well.

Organic micropollutants, like pesticides and pharmaceuticals, are frequently detected in surface water as a result of emissions from sources like agriculture, industry and households. Surface water is an important drinking water source. Due to their specific physical and chemical properties, micropollutants cannot be completely removed in drinking water treatment plants and are therefore occasionally detected in drinking water. Although they only occur in very low concentrations in surface and drinking water (ng/l up to μg/l), adverse effects on ecology (surface water) and public health (drinking water) cannot be ruled out due to many gaps in knowledge. To reduce the risk of organic micropollutants, legislation has been developed via decision-making processes at the level of the European Union (EU) to restrict their emissions. Initiated by the Water Framework Directive in 2000, over the last decennium Priority Substances (PS) have been identified – including several pesticides – which are bound to maximum acceptable surface water concentrations (Environmental Quality Standards, EQS). To protect their interests, many stakeholders – like the association of Dutch water companies, Vewin – attempt to influence EU decision-making. The research question answered is this thesis is: “Which recommendations can be formulated for Vewin to counter drinking water quality threats from organic micropollutants, based on a decision-making reconstruction regarding Priority Substances and given the European multi-stakeholder setting?” Pesticide emissions to surface water have been identified for decennia, while pharmaceuticals are an emerging problem for drinking water production. Nevertheless, their potential risk to or via the aquatic environment is regulated via the same legislative context as pesticides: the Water Framework Directive, specifically the identification of PS (1997 – 2001) and derivation of EQS (2002 – 2008). By reconstructing the decision-making processes regarding PS and EQS, factors that have a significant impact on the decision-making outcome can be identified and not only be used to counter the threat from pesticides, but the emerging threat of pharmaceuticals – and other micropollutants – as well. A theoretical model has been selected to assist in structuring the technical-substantive and social-strategic complexity. After careful consideration, the Advocacy Coalition Framework – initially developed by Paul Sabatier in 1988 – has been chosen because of its focus on stakeholder perceptions and the role of technical information within arguments. Advocacy coalitions are formed by stakeholders with a comparable belief system, and they have a lobby strategy to influence the decision-makers using their resources. To collect the data, document analysis has been undertaken and thirty interviews were conducted with representatives from coalitions and formal decision-makers.

Stimela is an environment for standardized mathematical models of drinking water treatment processes. It can be used to predict the future water treatment situation which may happen or change. In water treatment plant Wim Mensink, the Stimela model train was set up to compare with other alternative water control strategies. Before starting the work of developing new water control strategies with Stimela model, Stimela model for Wim Mensink must be validated so that the model can be seen as a reliable and stable tool for the next work. Before the validation work, the current water control strategy for the treatment process needs to be investigated clearly to fulfil all the input control information is correct. Besides this, an experiment for obtaining the measured results of pellet diameters over different layers was performed in Wim Mensink. The validation work starts with single pellet softening process for three different reactors over first month from January 20th to February 20th. The fluidized bed height, pressure drop over total height of reactor, pellet diameters and porosities are validated. After that, the validation work is integrated with whole water treatment system to prove the function of pellet softening reactor and the four important water quality parameters over two important locations (after weir aerator location and final RO mixing location). The validated results of softening process are analysed by the relative error way to prove the reliability of the model results compared with measured results. The final step of the thesis work is developing the new water control strategies to optimize the current control plans of Wim Mensink. Five different water control strategies are put forward. They can be either reached separately according to their own advantages and limitations or fulfil with a step by step order as a whole optimization process. Moreover, the other water control strategies developed by engineering consultancy company DHV are evaluated here with Stimela model so that they can be proved reliable and achievable. In the future, the application of Stimela model will be spread over all the drinking water treatment plants in the Netherlands and contributes to the central automated control as a drinking water treatment operator training simulator.

Desalinated water produced by reverse osmosis can generally be characterized as aggressive and corrosive water due to its low pH, low bicarbonate concentration and low hardness. Post treatment is required to remineralize desalinated water to comply with the Drinking Water Guidelines. Softening pellets, a “waste” product from the pellet softening process, have been investigated to be reused for the remineralization process due to its main composition of calcium carbonate. The remineralization process can include two sub-processes: (1) a dissolution process and (2) a filtration process. The implementation of dissolution process is considered as practical complement to the existing limestone filtration process. In the dissolution process the softening pellets are dissolved by carbon dioxide acidified water to make a chemical solution with high concentration of calcium, bicarbonate and carbon dioxide. This chemical solution can be mixed with desalinated water in a ratio of 1:50 to 1:100. In the filtration process the aggressive water is filtered over a bed filled with softening pellets. Theoretical calculations showed that softening pellets can be used to make chemical solution with high concentration of calcium, bicarbonate and carbon dioxide; a pressure of 1bar carbon dioxide gas was assumed as an applicable operational parameter in dissolution process. The results of dissolution experiments confirmed this assumption. The results of filtration experiments showed that softening pellets can be applied as a filtration medium for remineralization process; the reaction constant of the softening pellets filtration process was approximately 0.35min-1 which was comparable to limestone filtration. However, difficult removal of nuclear sand and impurities of softening pellets in filtration process limited this application.

In Suriname groundwater is mostly used for drinking water production. Depending on the ground layers from which groundwater is extracted, groundwater is characterized as aggressive water. The disadvantage of aggressive water is its ability to cause corrosion of metal pipelines and cement bound materials. In drinking water practice this water type is conditioned by means of air stripping, dosing of hydroxides or filtration through carbonate rich media. Currently the drinking water company SWM in Suriname suffers from water quality problems regarding low pH and occasionally low hardness and low alkalinity. These water quality problems are observed at pumping stations with aggressive raw water. Despite the conditioning of the aggressive groundwater by means of shell filtration, the drinking water quality does not satisfy the National Drinking Water Standards and VEWIN recommendations. It is noticed that in Suriname there are no strict guidelines for the water quality of drinking water and for the treatment of aggressive groundwater. Due to the fact that shells are also used for many other purposes such as the improvement and neutralization of acidic agricultural grounds, the shell provision is threatened to run out in the long term. Therefore it is important that alternative materials are found for shells. The objective of this research is to determine: Operational guidelines for several SWM pumping stations regarding necessary filter bed height, and refilling frequency of shell filters, Necessary treatment processes for several SWM pumping stations with water quality problems, based on water quality data of the raw water of the pumping stations.

A proved technique to upgrade (wastewater treatment plant) wwtp effluent to improved water quality is dead-end ultrafiltration (UF). Although the use of UF for upgrading wwtp effluent results in an excellent basic water quality, this technique faces problems due to membrane fouling. Especially particles in the size range between 0.1 and 0.45 @m (5 to 20 times larger than the membrane pores) are mainly responsible for membrane fouling. By the implementation of a pretreatment step for the dead-end UF installation, the particles in the critical fraction between 0.1 @m and 0.45 @m might be removed. Previous pretreatment methods did not give satisfying results. Apparently pretreatment with multimedia filtration, microfiltration and in-line coagulation with poly aluminium chloride (PACl), sometimes in combination with continuous sand filtration, did not remove the (effect of) these particles. Filterability did improve though, but only with a small percentage. In this research six pretreatment methods for dead-end UF are investigated. The objective of this research is to determine if the implementation of those pretreatment methods have any influence on the filterability of wwtp effluent. When an increase in filterability takes place, after a certain pretreatment step, the fraction in which the main filterability increase takes place, has to be determined. The six pretreatment steps were investigated on three different wwtp’s in the Netherlands. From February until May water was taken from wwtp Maasbommel. At this plant three pretreatment steps were involved; the dosage of NALMET (a polymeric substance, mainly for removal of heavy metals, the dosage of powdered activated carbon (PAC) and treatment with granular activated carbon (GAC). At wwtp Veendam experiments were carried out with a Fuzzy Filter in April. From July until September investigations started at wwtp Horstermeer with two different techniques; a multimedia filter and treatment of wwtp effluent with water fleas (Daphnia). The collected samples were fractionated which divides a sample in four fractions; the raw fraction, <0.45 μm, <0.2 μm and <0.1 μm. The filterability of every sample was measured on pilot scale with the Specific Ultrafiltration Resistance (SUR). This method has been developed at the Delft University of Technology. With the SUR the impact of pretreatment on the initial filterability can be indicated. It can be measured in a short period of 30 minutes. A low SUR value indicates good filterability. Besides measuring filterability of every fraction, five foulant concentrations were determined as well; Total Organic Carbon (TOC), colour, polysaccharides, proteins and humic substances. At wwtp Horstermeer filterability of effluent treated with a multimedia filter was measured on pilot scale. Three different fluxes were applied. Of the six applied pretreatment methods for ultrafiltration, only two did improve filterability of the effluent. Pretreatment with the four other methods resulted in no change in filterability or even a worse filterability, compared with the effluent. Filterability increase was achieved after dosage of NALMET and after treatment with GAC. NALMET did improve the filterability with 40 to 55%, GAC lowered the SUR with 0 to 40%. PAC did cause problems at wwtp Maasbommel. The carbon apparently falls apart in very small fractions which subsequently have a bad influence on filterability. Inspection at the pilot plant of wwtp Maasbommel revealed broken membranes due to friction, resulting in fractions of PAC in the filtrate. Treatment with the Fuzzy Filter did not have any influence on the filterability during this research. Contrary to previous researches, filterability decreased after multimedia filtration. The treatment process at wwtp Horstermeer differed from other experiments by the dosing of methanol which makes it an anaerobic process. Formed biopolymeric components during this process probably have a bad influence on the filterability. Daphnia did not increase the filterability either. The vessels with the water fleas were situated outside where the residence time is four days. This long residence time probably allows biological growth and subsequently a worse filterability compared with the effluent. From this research can be concluded that the main contribution to the filterability is caused by particles in the fraction of 0.1 to 0.2 μm. This fraction is for 45 to 70% responsible for the total SUR. Filterability increase, which happened by treatment with NALMET and GAC, was mainly caused by the removal of particles in the fraction >0.45 μm. Pretreatment with NALMET and GAC is not able to effectively remove the (effect of) the most important membrane fouling fraction of 0.1 - 0.2 μm. Treatment with PAC and GAC did remove proteins, colour and humic substances. Polysaccharides accumulated in front of the membrane, resulting in high concentrations. No change was determined after treatment with GAC. After dosage of NALMET concentrations of TOC, DOC, proteins and humic substances increased. Concentrations of polysaccharides and colour stayed more or less constant. Treatment with a Fuzzy Filter did not have any effect on all the measured foulants in this research. Varying results were obtained after both multimedia filtration and Daphnia. No foulant did increase or decrease structurally after both pretreatment methods. High SUR values go hand in hand with high concentrations of proteins, colour and humic substances. This is not the case for TOC and polysaccharides. Foulants could not be related to filterability per fraction. The total SUR is mainly caused by particles in the fraction between 0.1 and 0.45 μm, while most of the foulants are present in the fraction <0.1 μm. For removing the most important membrane fraction, other options should be investigated. Other methods which might remove the critical fraction are a precoat layer, ozonation and slow sand filtration. Optimizing the configurations of the used pretreatment methods might give other results than illustrated here. Repetition of the experiments carried out for this research could confirm the outcomes of this thesis.

Advanced Oxidation Processes (AOPs) are innovative, cost-effective, catalyzed chemical oxidation processes for treating pollutants in low or high concentration from contaminated soil, sludge and water. The common used AOPs in drinking water treatment include UV/H2O2 process, UV/Ozone Process, UV/Titanium Dioxide and Fenton’s Reagent. AOPs are ultraviolet driven, which share predominance from photochemical technology, and often, give the clients dual benefit of both environmental contaminant treatment and disinfection. Endocrine Disrupting Chemicals (EDCs) are very disturbing contaminants measured in natural waters. Phenols and their tert-butyl derivatives are important contaminants belonging to EDCs. After a successful workshop for developing alternative drinking water treatments at Shanghai, AOPs with UV/H2O2 technology are chosen to remove 4-tert-butylphenol (4TBP) from Shanghai water. The kinetics of reaction was studied in the first part of this thesis. The results show that UV/H2O2 process can effectively decrease 4TBP concentration than hydrogen peroxide alone. Good free oxidation radical production can be achieved within UV dose range from 0 to 200mJ/cm2 by a low pressure mercury lamp. The 4TBP degradation process fits with pseudo first order equation for UV-dose and H2O2-dose. However, at very high H2O2-doses, the scavenging of hydroxyl-radicals needs to be taken into account. Computational Fluid Dynamics (CFD) modeling of UV reactor and validation of CFD model were studied in the second part of this thesis work in order to provide an applicable UV reactor design for the 4TBP treatment and also give possible reactor improvement suggestions. The CFD model used in this study is a 2-D model developed using software Comsol, V3.3a, based on a current UV reactor design at Kiwa Water Research, the Netherlands. The developed UV dose model includes three parts, a k-ε flow model, a UV intensity model and a random walk model. Different feed flow rates and different lamp configurations were studied by the model. The calculation results show that a higher feed flow rate contributes to a relative narrow UV dose distribution than the lower flow rate. With three lamp configurations, position 0 is the best among the three with the highest average UV dose as well as the narrowest dose distribution pattern. Model also predicted low pressure lamps have about 8% higher power output to UV dose efficiency than medium pressure lamps. Validation of the flow model was helped by flow measurements at Delft University of Technology. Experimental studies of velocity measurements by Laser Doppler Velocity Meter were conducted together with salt and dye dose experiments. After comparisons of model predictions and experimental measurements, it was found that the k-ε CFD flow model demonstrated generally good qualitative prediction of flow inside the reactor but failed to give correct prediction of recirculation zones behind the quartz tubes. There are dead zones of water at the top and bottom near the inlet of the reactor. Bigger areas exist behind the quartz tubes that have water recirculation than the model predicted, which may result 25% of more UV dose prediction by the model. And differences caused by 2-D model and 3-D measurements may result about 20% less UV dose model prediction. Current UV reactor design at Kiwa Water Research, position 0 and low pressure mercury lamps applied at a feed flow rate of 4.1m3/h appears to be an applicable design for advanced oxidation treatment of 4TBP by UV/H2O2 in Shanghai. High roughness quartz tubes walls and relative smaller ratio of reactor to feed pipe diameters are recommended to improve reactor performance in the recirculation and dead zones with current design. Further investigations of the dose model and UV-sensitive dyed microspheres particle tracking experiments are recommended.

This report presents a study of the effect of temperature on the sludge in the MBR and on filterability. For three wastewater characteristics the relation with the temperature and filterability is determined: the sludge viscosity, the soluble microbial products (SMP) concentration and the particle size distribution. Chapter 2 attends to the basic knowledge about wastewater treatment in general and MBR in special. In chapter 3 there is a detailed explanation of different ways the temperature might affect the wastewater and thus the filtration. In this chapter the objective of the study is given as well. Chapter 4 is about the experiment set-up and methods that are used. In chapter 5 to 8 the results are presented, starting with the general effect of wastewater temperature on the filtration. Chapter 6, 7 and 8 are about the particle size distribution, SMP concentration and viscosity respectively. Each of these three chapters includes theory about the specific subject, expected results according to the theory, additional experiment set-up, presentation of the results, discussion and a conclusion. A general conclusion is available in chapter 9. The conclusion is accompanied by some recommendations for further studies.

The topic of this thesis is a concept of zero liquid discharge for nanofiltration technology in drinking water treatment. Nanofiltration, defined as a process between Ultrafiltration (UF) and Reverse Osmosis (RO), is a rapidly emerging technology. The origin of NF membranes can be traced back to the late 1950s when it was developed to treat sea water. Now it is applied in drinking water treatment, wastewater treatment and oil separation and also in the food industry. It is even called the future process of 21st century. However, nanofiltration is also a controversial process because of the concentrate problem, especially for inland installations. In the Netherlands, this problem is more considerable due to the need of high quality of drinking water and the decreasing quality of the surface water. Concentrate contains high concentrations of dissolved organic and inorganic compounds in high concentration. The conventional approach of concentrate discharge to surface water becomes a growing problem due to the environmental guidelines from the authorities. The discharge of the concentrate is not the only problem. It is also a cost problem that 20% of the feed water is wasted. In the Netherlands, taxes are paid for extracted groundwater. Also the pretreatment is costly. So with every m3 discharged concentrate money is wasted. Therefore, there is a need for a technology by which the discharge of concentrate is not necessary. That is so-called Zero Liquid Discharge Technology. The primary problem to be solved with zero liquid discharge is the recovery. We expect through an innovative technology the nanofiltration membrane installation can be operated at very high recovery (99%) without increasing the treatment cost of drinking water. The cost for residuals treatment and disposal can be minimized because the amount of the concentrate is decreased about 20 times. A series of pretreatment processes is used for removing the scaling components from the feed water. The scaling components mainly include bivalent ions, silica and etc. Preventing fouling and scaling can guarantee a constant flux, reduce membrane area, lower chemical cleaning frequency, extend the lifespan of membrane and decrease energy consumption. In this research, a pilot experiment was performed with sludge softening, sedimentation, weak acid cation exchange and nanofiltration at Kiwa Water Research. By using this treatment process, the recovery can be handled successfully at 99% for at least 11 days. The pretreatment concept can remove the bivalent ions completely. Sludge softening is used to remove most of the bivalent ions, like calcium, magnesium and barium. The remaining bivalent ions can be effectively removed by weak acid cation exchange. In this way, the waste stream from the ion exchange is reduced. In theory, silica can be removed by sludge softening at high pH as the co-precipitation of of Mg(OH)2 and CaCO3. But in this experiment the removal efficiency of silica is low probably due to the shortage of magnesium in the feed water. After this treatment process, the remaining concentrate (1%) 3 is evaporated, only remaining salt which can be sold or discharged to a waste facility. In order to improve and guarantee the good performance of silica removal by sludge softening, a jar test is performed to define the influencing factor for silica removal. pH and the magnesium concentration can influence the silica removal efficiency. Higher magnesium concentration is necessary for silica removal. Also, a ternary ion exchange model is needed to predict the breakthrough of cation concentration in order to guarantee the good quality of the feed water for nanofiltration. A ternary system is more complex than binary system. This short report can not include all the aspects of this model. This is the first step to build a ternary model. In the first phase, the basic equation has been already found. The basic model concept has been built up, but needs to be checked and improved. And some batch experiments have been done to obtain model parameters like equilibrium constants and kinetic constants. Also two groups of column experiments have been done in order to measure breakthrough curves for Ca2+, Na+ and H+(pH). The experimental result is expected to be compared with the model result in the future. The pretreatment concept consisting of sludge softening at high pH (around 10), weak acid cation exchange in series can remove calcium, magnesium and barium completely. The calcium removal by the ion exchange is quite good. After pH breakthrough is reached, calcium still can be removed by the resin because it is exchanged with the sodium on the resin. With high magnesium concentration, silica concentration also can be reduced by the sludge softening to some extent. This combination of the treatment processes is possible to make the recovery of NF membrane reach 99% without scaling at least for 11 days. To put this innovative concept into practice needs lots of efforts on validation and testing. Stable operation of pilot experiment at 99% for a longer time is needed to check the feasibility of this concept. It is interesting and significant work. With increasing demand of drinking water, more and more people in this world needs this kind of technology to improve their living condition and environment. We expect the occurrence of this new big step of drinking water treatment technology.

Ion exchange resins have found an increasing application in the drinking water treatment sector over the last few decades. The ion exchange resins have a positive ability to remove the charged natural organic matter (NOM). To apply this process in full-scale treatment, the most suitable resin has to be selected and the hydraulic behaviour of the treatment process must be known. This study has the purpose to study the NOM fractions removal with different resins and select the most suitable resin for NOM removal of the Weesperkarspel water. Another purpose is to study the hydraulic behaviours of fluidized ion exchange and testing of the fluidization models of Ergun and Richardson-Zaki. The thesis study is characterizing NOM into the specific fraction and later observing the removal of each fraction with the different ion exchange resins. The kinetic and the equilibrium of NOM removal of each resin are also studied. Four ion exchange resins are tested (Lewatit VP OC 1071, Purolite Macronet 200, Duolite A7 and MIEX DOC). The ultraviolet absorbance method (UV), dissolved organic carbon detection method (DOC), specific ultraviolet absorbance (SUVA), fluorescence excitation emission matrix (fluorescence EEM) and liquid chromatography-organic carbon detector method (LC-OCD) were applied. Weesperkarspel water contains a high degree of aromatic NOM fractions, mostly in the form of humic substances. The Lewatit VP OC 1071 is the most suitable resin for removal of NOM in general view, especially aromatic NOM and humic substances fractions. It appears to be removed as high as 65% and 94% respectively. The MIEX DOC removed 57% aromatic NOM fraction and 70% of humic substances. The pH was found as the dominant parameter for the NOM removal by the weak base Duolite A7. In normal raw water (pH = 7.8), this resin is almost ineffective while it can remove the aromatic NOM up to 35% and humic substances fraction of 45% in raw water pH adjusted to 5. The sorbent Purolite Macronet 200 can remove only biopolymers and neutral NOM fractions. Adsorption is an important mechanism for the removal process of high molecular weight NOM fractions and the neutrals fractions. By using the linear driving force model (LDF) to describe the ion exchange rate of the resin, it was found that MIEX DOC resin can remove NOM faster than other resins. The LDF- k constant of MIEX DOC is also higher than other resins. MIEX DOC has the smallest resin bead size. This can be the reason for the fast removal of NOM. The resin exchange capacity is related with the Freundlich constant K and n . Increase of K and n values lead to increase of exchange capacity. The Lewatit VP OC 1071 has the highest K and n values and thus the highest exchange capacity. The exchange rate and exchange capacity is a specific property of each resin. With help from the LDF model and Freundlich isotherm the breakthrough curve can be determined. The Lewatit VP OC 1071 has longest running time compared with the MIEX DOC and Duolite A7 due to the highest exchange capacity. The hydraulics behaviour of fluidized bed ion exchange has been investigated with the strong base gel resin Lewatit VP OC 1071. The temperature and the feed velocity influence the expanded behaviour. The wet density and wet porosity are important parameters for the model prediction. Combination of mathematical modelling of ion exchange and the treatment conditions of Weesperkarspel drinking water treatment plant, the fluidized ion exchange process can be designed. For Weesperkarspel drinking water treatment plant, the aim is to decrease the DOC concentration of 7.2 mg C/l to 3.0 mg C/l with the fluidized ion exchange process. The 20 fluidized ion exchange reactors with a height of 9 m, 10 m2 of resin bed surface area, a bed height of 2 m and a feed velocity of 20 m/h are designed. The reactors consist of 4 groups, each group is started with delays of 15 days. With this operational step, the running time of each reactor is 60 days. The cost is estimated 11-euro cent per m3 treated water.

High concentrations of arsenic in drinking water form a major threat for public health in more than 70 countries worldwide. The situation is Bangladesh is seen as the worst incidence of arsenic poisoning: it is believed that 30 million people in Bangladesh are exposed to an arsenic concentration exceeding 50 μg/L. Recently subsurface treatment as a possibility for arsenic removal for drinking water supply on community scale in rural Bangladesh has been recognized. The application of this subsurface treatment technique for arsenic removal is seen as very promising, since it has many advantages: it is a residue free, low-cost technology and no hazardous chemicals or expensive filter media are required. The technique, already applied for decades in Europe for subsurface iron removal, involves the injection of aerated water into an anoxic aquifer, where consequently ferrous iron is oxidized by the injected oxygen. Subsequently, the flow is reversed and a multiple of the injected volume can be extracted with lowered iron concentrations, which makes the technology successful. Efficiency ratios (V/Vi) of extracted water (V) over injected water (Vi) are typically increasing over the successive cycles and may range from 3 to 30. The freshly formed ferric oxides are potentially effective adsorbents for trace elements like arsenic. Yet, there is a lack of insight in both (i) the fundamental knowledge of the responsible mechanisms causing the (increasing) sorption of iron and arsenic, and (ii) the operational factors through which the removal efficiency can be optimized. The primary goal of this study is to gain a better understanding of these dominant mechanisms and the observed increasing efficiency, in order to optimize the operation of this technology in the field.

Iron is the primary source for discolouration problems in the drinking water distribution system. The removal of iron from groundwater is a common treatment step in the production of drinking water. Even when clear water meets the drinking water standards, the water quality in the distribution system can deteriorate due to settling of iron (hydroxide) particles or posttreatment flocculation of dissolved iron. Therefore it is important to remove dissolved and particulate iron to very low levels. The objective of this study was to reduce the particle load towards the distribution system and to improve the iron removal at the groundwater pumping station Harderbroek, consisting of aeration, rapid sand filtration and tower aeration. A maximum flow of 1800 m3/h can be treated and the average production is 800 m3/h. Although previous research showed the clear water meets the drinking water regulations, the drinking water company Vitens is not satisfied with the turbidity and iron concentration of the clear water. The mean iron concentration is 0.04 mg/l.

During storm events, the flow in a combined sewer system can exceed the capacity and, as a result, a combined sewer overflow (CSO) will occur. During a CSO raw wastewater is discharged to surface water. This wastewater is a mixture of raw sanitary wastewater, raw industrial wastewater and rainwater. The receiving water will get polluted by dissolved as well as undissolved pollutants. Therefore a CSO can cause damage to the ecological and biological state of the receiving water and besides it can cause public health risks. Until now the problem, with respect to CSOs in the Netherlands, is dominated by a quantitative approach. CSO flow rates and frequencies were in the past decades the main subject of research. These frequencies were translated into the Wet Verontreiniging Oppervlaktewater (1970). In the year 1998 the Ministry of Transport and Water Management came with a renewed policy, the fourth Memorandum on Water Management, dealing with groundwater, dehydration and water quality, for the protection and the recovery of nature. At the end of 2000 the European Water Framework Directive (WFD) came into force, which charges the European members of the EU to report obligatory. The aim of the WFD is to have an ecological and biological balance for all surface waters and groundwater in Europe effectively working in 2015. Measures are required to push back the pollution by defined dangerous substances. Measures with regard to the reduction of CSO frequencies alone is not enough to fulfil the legislation. When a CSO occurs an amount of pollutants will enter the surface water. CSO water needs to be treated to prevent pollution and odour annoyances to the surroundings. The goal of this research is to find a suitable treatment technique or a combination of treatment techniques. Primary and secondary techniques, adsorption and disinfection techniques are described. Primary techniques remove suspended solids and a fraction of the organic material, secondary techniques remove suspended solids and biological degradable material. Adsorption techniques are used to remove for example endocrine disrupting substances and disinfection techniques are used to minimize health risks for the population. In the Netherlands CSOs occur five to ten times a year per location. Therefore a treatment technique needs to be able to start up in a few minutes even after a long period without feedwater and should be able to handle wide and quick variations in flow without causing any inconveniences to the surroundings. Primary techniques like sieving, the Netting TrashTrapTM system and sedimentation basins and secondary techniques like membrane filtration, sand filtration and synthetic medium filtration are described. Adsoprtion techniques like activated carbon filtration and ion exchange and disinfection techniques like ozone dosage, chlorine dosage and UV treatment are described.

In 1987 Amsterdam Water Supply, Waternet, discovered the presence of pesticides in the drinking water. Because of this the production process at Weesperkarspel has changed in 1992. The coagulation and rapid sand filtration are replaced by activated carbon filtration. At Weesperkarspel the activated carbon filters are pre-oxidised by the use of ozone resulting in an enhanced biological activity in the filters (BAC). Since the implementation of the BAC problems of rapid clogging have occurred. It is stated that during the summer the biological activity is high due to high water temperatures and the pressure builds up so fast that the filters need to be backwashed frequently. Due to this constraint it was decided in 1993 to lower the ozone dosage for water temperatures above 12 °C. However in respect to the biological conversion of natural organic matter (NOM) and the disinfection capacity an increase in ozone dosage is desired. The objective of this research is to determine what causes the clogging of the BAC. Several hypothesis were derived from an analysis of the process of Weesperkarspel and a literature study. By conducting experiments at the pilot plant of Weesperkarspel the influence of assimilable organic carbon (AOC), supersaturation and suspended matter are tested. Four parallel filters were operated in different ways; raw water → ozone → softening (supersaturated) → acid dosing → BAC 1 raw water → ozone → softening (supersaturated) → BAC 2 raw water → ozone → BAC 3 raw water → ozone (company) → softening (company) → BAC 4 (reference filter) During 3 settings the ozone dosage varied from no ozone to a ozone dosage of 2.4 mg/l. Results of the research show that clogging is a combination of several factors. At Weesperkarspel clogging occurs in the top layer of the filter. The conversion of AOC in the pellet reactors results in a drop in AOC concentration of 50%. The highest pressure drop is achieved in BAC 3 where the AOC concentration is the highest. Literature study shows that the volume in the filter material occupied by living biomass is negligible if compared to other substances like suspended matter, alqae, etc. But research to the presence of extra cellular polymeric substances (EPS), which are essential for the survival of bacteria in the filter, in slow sand filtration shows that EPS can contribute to a decrease in pore space of 7% and the most severe clogging occurs in the top 5-10 cm of the filter. EPS is also highly hydrated because it can incorporate large amounts of water into its structure by hydrogen bonding. So despite the volume of biomass is low, the presence of EPS surrounding the biomass in combination with hydrogen bonding can result in a large volume which can encounter for the clogging of the filter. The influence of supersaturated water on the pressure build up in the filter can be derived from the differences in pressure between BAC 1 and 2. A high saturation index seems to result in a turbidity because of the presence of, possibly strongly hydrated, calcium carbonate particles. The results of the pilot plant experiments are used to calibrate a model. The model gives good predictions of the pressure build up for water temperatures higher than 15 °C. But due to the differences in pressure build up in BAC 4 (reference filter) and the filters in the treatment plant a conversion needs to be made to the water treatment plant. The objective of the model is that it can be used to make predictions of the filter run times according to the water quality parameters. As a result an optimization of the backwash frequency can be accomplished.

With the development of industry, many new micro pollutants are found in the water sources for drinking water. For instance endocrine disrupting compounds, pharmaceuticals, personal care products, MTBE are reported. However, the conventional water treatment has limited removal efficiency for these components. Therefore, in order to deal with these substances, we introduce a new treatment concept: fluidized Ion exchange---UF---NF---GAC adsorption. With this treatment concept, we obtain a double barrier (UF-NF) for particles and microorganisms; double barrier (NF-GAC adsorption) for the micro pollutants and natural organic matter. The main problem of this concept is the membrane ouling, so we use fluidized cation exchange system to remove an important fouling factor in membrane filtration---calcium. Experiments are performed to demonstrate the positive effect of calcium removal on the prevention of membrane fouling, check the effectiveness of treatment concept on target substances, and set up the model of fluidized IEX system. The results showed that both monovalent and multivalent ions on the membrane surface are crucial fouling factors, and Fluidized IEX system is a good pretreatment for membrane filtration. The treatment concept was good in removing target substances, except the polar ones with molecule weight smaller than 100 Da. For the modeling of fluidized IEX system, pH is an important parameter, which determines the exchange capacity.

Worldwide limestone (CaCO3) filtration is used in many treatment plants for the conditioning and (re)mineralization of drinking water. The goals are to increase the concentrations of Ca2+ and HCO3-, the pH and the Saturation Index (SI), thereby improving the quality of the water regarding corrosion control, buffering and taste. Typical applications include (very) soft groundwater with (very) low alkalinity and desalinated water. In Norway, some plants use a product made of ground natural limestone, called Micronized CaCO3 Slurry (MCCS), which is dosed as a slurry of fine particles (order of 1-2 μm) into the raw water. In this research a study is made of the potential of MCCS as an alternative to limestone filtration. Experiments were performed to determine the dissolution kinetics of MCCS and other CaCO3-products, including natural limestone grains (1-2 mm) and two precipitated CaCO3 (PCC) powders (Heyer test powder and NanoPCC powder), that consist of even finer particles than MCCS (down to 0.088 μm). The experimental setup consisted of jars containing water in which the CaCO3-product was introduced. An increase in conductivity as a function of time was observed, which could be used to describe the dissolution kinetics. As expected from theory, the dissolution kinetics are strongly influenced by the particle size of the CaCO3 and the driving force towards the chemical equilibrium. However, all CaCO3-products needed substantial detention times (30 minutes and more) to dissolve completely. This severely hampers the feasibility of MCCS as an alternative to limestone filtration, which can be operated with an Empty Bed Contact Time in the same order of magnitude. This finding can be explained by the fact that the available mass/volume of CaCO3 in a limestone filter is much higher than the available mass/volume of particles in the dosed slurry, thus compensating for the difference in particle size. It is concluded that MCCS is generally not a feasible alternative for limestone filtration as a stand-alone option for the conditioning and (re)mineralization of drinking water. Applications of MCCS will be limited and should either be found in combinations with coagulation/filtration (which is the actual mode of operation in Norway and limits the problems associated with non-complete dissolution of the CaCO3) or in combination with other conditioning and (re)mineralization methods (by dosing a limited amount of MCCS to the raw water, which limits the problem of the slow kinetics).

Scaling is a major barrier in increasing recovery of RO installations. One of the major unresolved scaling problems in RO is silica scaling. Depending on pH and temperature, the safe operation practice to prevent silica scaling is to keep silica concentration below 150 [mg/l] in the concentrate. In this study, it was investigated whether it is possible to gain the high recovery and the very high silica concentration by removing divalent ions from the feed water by using ion exchange column. A total recovery of 90% is achieved without using antiscalant and with constant flux. The results show that in absence of antiscalant and divalent ions, silica concentration of about 280 [mg/l] in concentrate is possible without declining of mass transfer through the membrane.

Trimethylene glycol dimethyl ether (triglyme), a Polyethylene glycol (PEG)-like hydrophilic polymer, was deposited by plasma polymerization to reduce RO membrane’s organic fouling tendency. This method has the great advantage of achieving modification in one single step. A series of plasma deposition experiments were undertaken. The successful coating of the polymer was confirmed by X-ray photoelectron spectroscopy (XPS) analysis. Water contact angle measurements and permeation experiments using a protein solution were conducted to evaluate the change of hydrophilicity and anti-fouling properties. Salt rejection tests were performed to evaluate membrane performance. A reduction in contact angles from 32 o to 7 o was achieved for the treated membranes, indicating enhanced hydrophilicity. The permeation experiments revealed that the modified membranes achieved an excellent maintenance of flux compared to the untreated membranes. Specifically, after 210 minutes of filtration, no flux decline was found for the modified membranes, while a 27% reduction of the initial flux was observed for the untreated membrane. Flux recovery after cleaning by water only was up to 99.5% for the modified membranes, while for the untreated it was only 91.0%. The surface hydrophilic modification of RO membranes by plasma polymerization has shown a clear improvement in membrane anti-fouling performance.

In 2008, the author has conducted a research study on behalf of the Caribbean Water Association on the consequences of the constitutional change of the Netherlands Antilles for the drinking water supply on Bonaire, St Eustatius and Saba (BES). This research study formed the basis for further research in the form of this MSc. thesis. Being the responsible Ministry for the supply of drinking water on the future BES islands, VROM positively embraced the idea to study solution alternatives to improve the current situation on the BES islands. The Ministry of VROM granted the author with the financial means and support to conduct this thesis research study. In chapter 7 of this report a set of guidelines and instruments is presented that can support the Ministry of VROM in defining and preparing an improved drinking water supply on the BES islands.