Дисертації з теми "Drinking water treatment processes"

Removal of natural organic matter (NOM) is an ever growing challenge for water utilities as many surface waters used for drinking water in the UK exhibit increasing organics levels and it is well known that these organics can lead to problems such as water colouration, unpleasant odour and taste, bacterial growth and disinfection by-products (DBPs) formation. NOM is traditionally removed by coagulation, however in the case of hydrophilic organic matter rich waters the performances of these processes are not able to remove sufficient organic matter leading to potential failures of DBP regulations. Here two advanced oxidation processes (AOPs) UV/H2O2 and TiO2 photocatalytic oxidation were studied to investigate how they could be integrated in a drinking water flowsheet to meet this challenge. Substantial structural changes in the organic matter were observed: loss of aromaticity and double bonded character, shift towards lower molecular weight (MW) more hydrophilic compounds and formation of oxygenated by-products. Although hydrophobic rich waters seem more suitable to AOP treatment as preferential attack of high MW hydrophobic compounds was demonstrated, no correlation was found between physical properties of nine NOM surrogates and removal by UV/TiO2. Dark adsorption onto TiO2 was shown to remove preferentially high molecular weight hydrophobic anionic compound such as tannic acid. UV/H2O2 combined with coagulation did not show any significant benefits in NOM removal as UV/H2O2 appeared to target similar components as coagulation (high MW, hydrophobic and charged) and to form by-products recalcitrant to coagulation. The combination of both AOPs with fresh GAC showed moderate benefits in Abstract ii trihalomethane formation potential (THMFP) and non purgeable organic carbon (NPOC) removal highlighting the role of size and surface chemistry on adsorption onto GAC. Biodegradability of the water did not exhibit any significant change after both AOP treatments within the studied conditions possibly due to insufficient UV irradiation and presence of organics recalcitrant to biodegradation.

In recent years advances in analytical techniques have resulted in the reporting of previously undetectable pesticides in treated drinking water. Most pesticides are traditionally removed using ozone and granular activated carbon, however polar pesticides such as metaldehyde are not effectively removed in this way. Biological treatments for drinking water are a potential option for metaldehyde removal. Experiments were undertaken firstly to understand if metaldehyde can be removed using a biological mechanism and whether this mechanism can be captured and enhanced. It was found that metaldehyde can be effectively degraded using a sand with an active biofilm. This mechanism can be enhanced using a period of acclimation where the biofilm is exposed to higher metaldehyde concentrations to achieve increased degradation rates, this rate is maintained for several days even in the presence of lower metaldehyde levels. Removal times can also be enhanced using a fluidised column, which was found to be more effective that a traditional downflow filter for metaldehyde degradation. Pilot scale experiments demonstrated the potential for this technology to be implemented at full scale. Finally, an economic analysis identified that a fluidised bed bioreactor is economically viable compared to current treatment options.

Dissertation presented to obtain the Ph.D degree in Engineering and Technology Sciences, Chemical Engineering.
Water is a fundamental resource for life. The presence of hazardous micropollutants such as pesticides and hormones in drinking water sources as well as the evidence of their presence in several treated waters raised concerns regarding the quality of the water intended for human consumption. The development of new technologies which are able to cope with these micropollutants and ensure the fulfillment of future more stringent regulations is therefore needed. Low pressure ultraviolet direct and indirect photolysis (using hydrogen peroxide and titanium dioxide) and nanofiltration are extremely promising technologies to effectively remove organic micropollutants from water.(...)

This thesis focused on the feasibility of substituting, partially or totally, drinking water treatment plant (DWTP) conventional pre-treatment by membrane based units, in particular by ultrafiltration (UF). For such purpose, bench and pilot scale tests with natural water were conducted, first, to address the technical feasibility and, second, to optimize its performance in order to determine whereas the proposed scheme was competitive from hydraulic and quality perspectives with the current conventional pre-treatment. Moreover, tailored microbes based tests were defined to assess its proper functioning and reliability, and additional advantages related to direct UF besides those purely related to the pre-treatment unit were investigated. The case study selected was Sant Joan Despí DWTP (Barcelona, Spain) due to its particularities: it treats Llobregat River water, which is a highly variable water resource in terms of quality and quantity, and it is a complex multistage system. As a result, this study covered a wide range of conditions and the technology under consideration could be pushed to its limits. Results showed that direct UF of raw river water was a competitive alternative to dioxichlorination, coagulation/flocculation, settling and sand filtration. The pilot plant was able to continuously treat raw river water during 2 years, independently of its quality (e.g. turbidity > 1,000 NTU), delivering water of high and stable quality, both physico-chemically and microbiologically. In terms of pre-treated water quality, most of the physico-chemical parameters monitored presented lower values and variability in the direct UF scheme than in the conventional pre-treatment process. From a microbiological perspective, the direct UF scheme tested ensured an average removal of > 5 log10 units of bacteria and viruses greater than 60 nm. The highest water yields achieved ranged between 94.0%-94.7% in optimal conditions, involving 1 or 2 chemically enhanced backwashes (CEBs) per day, transmembrane pressure (TMP) below 1 bar, filtration fluxes of 40¿70 L/(m2¿h) and low reagents consumption. When a micro-coagulation previous to the UF was applied, the increase of the hydraulic resistance during filtration was decreased and stabilized, especially in winter, the hydraulic cleaning efficiency raised and the CEB frequency diminished. Since fouling indicators (SDI15 and MFI0.45) of the direct UF permeate were lower than those associated to the conventional pre-treatment, the subsequent reverse osmosis (RO) unit would require less chemical cleanings and thus, its lifetime would be extended. In addition to this, besides the economic savings associated to the significant reduction of reagents dosed within the direct UF scheme (chemical disinfectants and coagulants mainly), a minimization of risk of RO membrane degradation was demonstrated. Studies concerning the effects on physico-chemical and transport properties of RO membranes exposed to chemicals used within the conventional pre-treatment scheme but avoided in the direct UF treatment were also undertaken. An advanced characterisation of the exposed membranes enabled understanding the RO membranes performance changes with its composition and structure modification. The implementation of direct UF would imply the pre-treatment being a single membrane filtration step. This has advantages in terms of process complexity, space requirements, as well as avoidance of chemical based disinfectants dosage. Nevertheless, the preservation of its separating properties along time is of utmost importance, especially from a microbiological standpoint. Consequently, microbes based tailored tests aiming at assessing membrane integrity were defined and conducted periodically, to determine the removal capacity reliability of the pre-treatment scheme proposed in this thesis. Results showed that membrane integrity had not been compromised despite the challenging conditions that direct UF posed.
Aquesta tesis s'ha centrat en l'estudi de la substitució, total o parcial, de l'etapa de pre-tractament d'estacions de tractament d'aigua potable (ETAPs) per processos de membrana, en particular per ultrafiltració (UF). Per a tal fi, es van realitzar experiments a nivell laboratori i pilot per, en primer lloc, avaluar la seva viabilitat tècnica, i en segon, optimitzar el seu funcionament per determinar així si l'esquema de tractament proposat era competitiu des d'un punt de vista hidràulic i de qualitat amb el pre-tractament convencional actual. A més, es van definir assajos per assegurar el seu correcte funcionament i fiabilitat, i es van identificar avantatges addicionals a les purament associades a l'etapa de pre-tractament. El cas d'estudi seleccionat va ser l'ETAP de Sant Joan Despí (Barcelona) degut a les seves particularitats: tracta aigua del riu Llobregat, que és un recurs altament variable en termes de qualitat i quantitat, i és un sistema multi-etapa complex. En conseqüència aquest estudi va cobrir un ampli rang de condicions i va permetre portar la tecnologia en qüestió a condicions límit. Els resultats vam mostrar que la UF directa d'aigua crua de riu és capaç de substituir, i resulta competitiva, amb la dioxicloració, coagulació/floculació, decantació i filtració per sorra. La planta pilot va ser capaç de tractar contínuament aigua crua durant 2 anys, independentment de la seva qualitat (ex. terbolesa d'entrada > 1000 NTU), produint aigua de qualitat alta i estable, tant fisicoquímicament com microbiològicament. La majoria dels paràmetres fisicoquímics avaluats van presentar valors inferiors i amb menor variabilitat en l'esquema d'UF directa que en el pre-tractament convencional. Des d'una perspectiva microbiològica, l'esquema d'UF directa avaluat va assegurar una eliminació > 5 log10 unitats de bactèries i virus de tamany superior a 60 nm. El rendiment hídric va oscil.lar entre 94.0-94.7% en condicions òptimes, requerint 1 o 2 contra rentats químics al dia, una pressió transmembrana per sota d'1 bar, fluxos de filtració entre 40-70 L/(m2.h) i un baix consum de reactius químics. En aplicar una micro-coagulació prèvia a la UF, l'increment de la resistència hidràulica durant la filtració va disminuir i es va estabilitzar, l'eficiència del contra rentat va augmentar, i la freqüència dels contra rentats químics va davallar. Degut a que els indicadors d'embrutiment (SDI15 i MFI0.45) del permeat d'UF directa van resultar inferiors als del pretractament convencional, és d'esperar que la unitat següent d'osmosis inversa (OI) precisi menys neteges químiques i per tant, la seva vida útil es prolongui. Addicionalment, a part de l'estalvi econòmic associat a la reducció significativa de reactius dosificats en l'esquema l'UF directa (desinfectants químics i coagulants principalment), es va demostrar una disminució del risc de degradació de les membranes d'OI. Es van dur a terme estudis avaluant els efectes de l'exposició de certs químics (dosificats en el pre-tractament convencional però no en l'UF directa) en les propietats fisicoquímiques i de transport de membranes d'OI. Una caracterització avançada va permetre relacionar els canvis de funcionament de les membranes d'OI amb els seus canvis de composició i d'estructura. La implementació de la UF directa implica que el pre-tractament consisteixi únicament en una etapa de filtració. Això suposa avantatges en termes de complexitat del procés, requeriments d'espai així com d'evitar l'ús de desinfectats químics. Tanmateix, la preservació de les seves propietats de separació al llarg del temps és de gran importància, sobretot des d'un punt de vista microbiològic. En conseqüència, es van definir i dur a terme periòdicament assajos en base a microorganismes per avaluar la integritat de la membrana d'UF directa. Els resultats van indicar que la integritat de la membrana d'UF s'havia preservat durant els 2 anys d'estudi, malgrat les condicions severes que la UF directa va suposar

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2004.
Includes bibliographical references (p. 52-55).
Low concentrations of xenobiotic chemicals have recently become a concern in the surface water environment. The concern expands to drinking water treatment processes, and whether or not they remove these chemicals while going through the treatment plant. In this study, the concentrations of organophosphoric acid triester flame retardants tributyl phosphate, tri(2-chloroethyl) phosphate, and ethanol, 2-butoxy-, phosphate (3:1) were measured after major treatment processes at the Chattahoochee Drinking Water Plant in Atlanta, Georgia, USA. The findings indicated significant removal of all three organophosphate triesters after the pre-treatment chemical addition of sodium hypochlorite. The interaction of sodium hypochlorite and organophosphate triesters, through oxidation, was suspected to be the reason for the removal. Second, the concentrations of tri(2-chloroethyl) phosphate after the filtration stage and at the clearwell were much greater than values after the sedimentation stage, and were well above the concentration measured at the intake. Exposure to the chemicals within the treatment plant was the chief potential reason for the heightened concentrations.
by Joseph C. Lin.
M.Eng.

The arsenic maximum contaminant level (MCL) for drinking water is likely to be lowered sometime in 2001 or 2002. If the MCL is lowered, it is speculated that there will be stricter limits imposed on the disposal and handling of arsenic-containing residuals. The purpose of this study is to determine the properties of drinking water residuals, including the chemical characteristics, the amount of arsenic that leaches in common residual handling and dewatering processes, and the hazardous potential of the residuals. Residual samples were collected from seven utilities with high arsenic concentrations in their raw water. Included in the study were four plants that coagulate with ferric chloride, two with aluminum hydroxide, and one softening plant. The residuals from each facility were acid digested and chemically characterized using ICP-AES to determine the total arsenic, aluminum and iron present. TCLP and California WET were performed to verify if the residuals were hazardous. Simulated lagoons were set up and monitored over a six-month period to determine the amount of arsenic that was leached to the liquid portion over time. Toxicity testing was performed on the residuals at 20% and 100% after two months and six months of storage. Bench-scale sand drying beds were used to dewater residuals, and the leachates were analyzed to determine if arsenic leached from residuals. The residuals were found to contain high levels of arsenic during the chemical characterization. However, all of the facilities passed the current TCLP limit of 5 mg/L. For all residuals, the California WET values were much higher than the TCLP values. In the lagoon study, redox potentials decreased and the arsenic and iron concentrations in the liquid portions increased. In the sand drying beds, very little arsenic leached; arsenic concentrations in the leachate were less than 10 ppb. Lagoon storage may not be a safe alternative for residuals containing arsenic. However, sand drying does not appear to present any threats. There were differences between the toxicity tests performed at 100% solids and 20% solids in the lagoon study. Some of the values increased and others decreased. Additionally, toxicity testing conducted after lagoon aging differed from earlier toxicity testing, due to the changing soluble arsenic. These discrepancies suggest that the test results can be affected by the percent solids and age of the residuals, and specific instructions should be given for consistent residuals testing.
Master of Science

This dissertation investigates the factors which affect the removal of arsenic from groundwater by adsorption and coagulation technologies, including the interactions between As and natural organic matter (NOM). Humic acid (HA) was utilised as an NOM analogue, and was shown to be capable of both complexing and oxidising As, depending upon the prevailing conditions. The arsenic removing capabilities of three iron oxide coated sands (IOCS) were investigated, including IOCSW, a waste material from a local drinking water treatment plant generated during the removal of iron and manganese. IOCSW was highly effective at removing both As(V) and As(III) from synthetic water matrices (qmax = 78.3 µg As(V)/g and 99.1 µg As(III)/g). The negative effects of competitive anions (phosphates, silicates and HA) on arsenic removals were not significant enough to preclude the application of IOCSW for arsenic removal during drinking water treatment. The removals of both As and NOM by coagulation and enhanced coagulation with pH correction and preoxidation were also investigated. As(V)  was more readily removed by coagulation than As(III), so that the most efficient coagulation treatment investigated for arsenic and NOM removal applied preozonation with subsequent combined coagulation with polyaluminium chloride and ferric chloride. Different groundwaters displayed large variations in the As and NOM removal behaviours. Response surface methodology (RSM) was therefore applied to investigate  the interactions between As and NOM during ferric chloride coagulation and optimise their combined removals. Multiple interaction effects were observed during this investigation, highlighting the importance of utilizing RSM to optimise drinking water treatment technologies.
Ova disertacija ispituje faktore koji utiču na uklanjanje arsena iz podzemne vode primenom adsorpcija i koagulacije, uključujući i interakcije između arsena i prirodnih organskih materija (POM). Huminska kiselina (HA) je korisćena kao model za POM, a pokazano je da može i da kompleksira i da oksiduje As, u zavisnosti od eksperimentalnih uslova. Ispitivane su mogućnosti uklanjanja arsena za tri peska obložena gvožđe oksidom (IOCS), uključujući IOCSW, koji je dobijen sa postrojenja za tretman vode za piće i potiče iz procesa uklanjanja gvožđa i mangana. IOCSW se pokazao kao visoko efikasan za uklanjanje As(V) i As(III) iz sintetičkih vodenih matriksa (q_max = 78.3 µg As(V)/g i 99.1 µg As(III)/g). Negativni efekti kompetirajućih jona (fosfata, silikata i HA) na uklanjanje arsena nisu bili dovoljno značajni da bi se isključila primena IOCSW za uklanjanje arsena tokom tretmana vode za piće. Zajedničko uklanjanje As i POM koagulacijom i unapređenom koagulacijom uz podešavanje pH i kombinovanje sa oksidacionim predtretmanima je takođe ispitivano. Bolje uklanjanje koagulacijom postignuto je za As(V) u odnosu na As(III), stoga se kao najefikasniji ispitivani koagulacioni tretman pokazalo uklanjanje arsena i POM primenom predozonizacije praćene kombinovanom koagulacijom sa polialuminijum hloridom i gvožđe hloridom. Ispitivanja na različitim podzemnim vodama, pokazala su velike varijacije u ponašanju As i POM tokom tretmana. Iz tog razloga je primenjena metodologija odzivne površine (RSM) u cilju ispitivanja interakcija između As i POM tokom koagulacije gvožđe hloridom i optimizacije njihovog kombinovanog uklanjanja. Sagledavanje većeg broja interakcija primenom metodologije odzivne površine potvrđuje važnost njegove primene pri optimizaciji tretmana vode za piće.

Clean drinking water is a vital part of our society and a basic human right. With an ever growing population and a decreasing quality of raw water, new methods need to be introduced to keep up with the demand for clean, biostable, and sustainable production of drinking water. The aim of this study is to evaluate Håbo municipality’s increasing usage of chemicals in their water treatment process and to investigate current and future possible technologies for water treatment for Håbo to make their process more sustainable. In this study four scenarios of different cost and change of today’s water treatment plants are presented, while our overall recommendation is to build a new facility. A new plant with new treatment methods such as ultrafiltration is most in line with Håbo municipality’s vision of decreasing chemical usage and sustainability, all while maintaining the water quality. Due to Håbo’s growing population and today’s water plants running close to maximum capacity, a new facility with a larger capacity should be considered.

Natural organic matter (NOM), ubiquitous in natural water sources, is generated by biogeochemical processes in both the water body and in the surrounding watershed, as well as from the contribution of organic compounds that enter the water as a result of human activity. NOM significantly affects the properties of the water source, including the ability to transport metals, influence the aggregation kinetics of colloidal particles, serve as a food source for microorganisms and act as a precursor in the formation of disinfection by-products (DBPs), as well as imparting a brown colour to the water. The reactivity of NOM is closely tied to its physicochemical properties, such as aromaticity, elemental composition, functional group content and molecular weight (MW) distribution. The MW distribution is an important consideration from a water treatment perspective for several reasons. For example, low MW NOM decreases the efficiency of treatment with activated carbon, and this fraction is thought to be the portion most difficult to remove using coagulation. The efficiency of membranes in the treatment of drinking water is also influenced by the MW distribution of NOM, while some studies have shown that the low MW fraction contributes disproportionately to the formation of bioavailable organic matter, therefore promoting the formation of biofilms in the distribution system. For these reasons, understanding the MW distribution of NOM is important for the treatment of natural waters for use as drinking waters. Optimisation of a high pressure size exclusion chromatography (HPSEC) method for analysis of the MW distribution of NOM in natural waters is described (Chapter 2). Several parameters influencing the performance of HPSEC are tested and an optimised set of conditions illustrated.These parameters included eluent composition, ionic strength of the sample, flow rate and injection volume. Firstly, it was found that increasing the ionic strength of the HPSEC eluent resulted in less exclusion of NOM from the stationary phase. Stationary phases used in HPSEC contain a residual negative charge that can repel the negatively charged regions of NOM, effectively reducing the accessible pore volume. By increasing the ionic strength, interactions between the stationary phase and eluent enabled a larger effective pore size for the NOM analytes. However, increasing ionic strength of the eluent also resulted in a loss of peak resolution for the NOM portion able to access the pore volume of the stationary phase. Determining the ideal eluent composition required the balancing of these two outcomes. Matching of the ionic strength of the sample with the eluent was also an important consideration. Retention times were slightly lower when the sample ionic strength was not matched with the eluent, especially for the lowest MW material, although the effect on chromatography was minimal. Flow rate had no effect on the resolution of the HPSEC chromatogram for the portion of material able to permeate the pore space of the stationary phase. Changes in the volume of sample injected had a marked effect on the elution profile of the NOM sample. Besides the obvious limitation of detection limit, only minor changes in elution profile were obtained up to an injection volume of 100 µL. Volumes above this value, however, resulted in significant peak broadening issues, as well as an undesirable effect on the low MW portion of detected DOC.In Chapter 3, high pressure size exclusion chromatography with UV254 [subscript] and on-line detection of organic carbon (HPSEC-UV254[subscript]-OCD) was used to compare the removal of different apparent MW fractions of DOC by two process streams operating in parallel at the local Wanneroo groundwater treatment plant (GWTP). One of these two process streams included alum coagulation (operating in an enhanced coagulation mode (EC) for increased DOC removal) and the other stream included a magnetic ion exchange (MIEX®) process followed by alum coagulation (MIEX®-C). The MIEX® process is based on a micro-sized, macroporous, strong base anion exchange resin with magnetic properties, which has been designed to remove NOM through ion exchange of the anionic sites in NOM. Water was sampled from five key locations within these process streams, and the DOC at each location was characterised in terms of its MW distribution. HPSEC was carried out using three different on-line detector systems, namely OCD, UV absorbance detection at 254 nm, and fluorescence detection (λex[subscript]= 282 nm; λim[subscript] = 353 nm). This approach provided significant information on the chemical nature of the DOC in the various MW fractions. The MIEX®-C process was found to outperform the EC process: these two processes removed similar amounts of high and low MW DOC, but the MIEX®-C process showed greater removal of DOC from the intermediate MW fractions. The two coagulation processes (EC and coagulation following MIEX®) showed good removal of the fractions of highest MW, while the MIEX® process alone was found to remove DOC across all MW fractions.These results seem to indicate that anionic groups, particularly susceptible to removal with MIEX® treatment, are well distributed across all MW fractions of NOM. In agreement with previous studies, MIEX®-C outperformed EC in the overall removal of DOC (MIEX®-C removed 25 % more DOC than EC). However, 70% of the additional DOC removed by MIEX®-C was comprised of a surprisingly narrow range of medium-high MW fractions. The development of a novel online organic carbon detector (OCD) for use with HPSEC for determining the MW distribution of NOM is described in Chapter 4. With UV absorbance detection, the magnitude of the signal is based on the extinction coefficient of the chromophores in the analytes being investigated; whereas the signal from an OCD is proportional to the actual organic carbon concentrations, providing significantly more information. The development of an online OCD involved the separation of analytes using HPSEC, removal of inorganic carbon species which may interfere with organic carbon determination, oxidation of the organic carbon to carbon dioxide, separation of the produced carbon dioxide from the aqueous phase and subsequent detection of the gaseous carbon dioxide. In the new instrument, following separation of components by HPSEC, the sample stream was acidified with orthophosphoric acid to a concentration of 20 mmol L-1[superscript], resulting in a pH of ≤ 2, in order to convert inorganic carbon to carbon dioxide. This acid dose was found to remove greater than 99 % of inorganic carbon once the acidified sample was passed through a hydrophobic polytetrafluoroethylene (PTFE) membrane allowing the passage of dissolved gases (under negative pressure from a vacuum pump) but restricting the flow of the mobile phase.Several factors influenced the oxidation of the organic carbon in the next step, including the dose of persulfate, the type and intensity of UV radiation and the composition of the capillary through which the sample stream passes. Through optimisation of this process, it was found that a persulfate dose of 0.84 mmol L-1[superscript] in the sample stream was required for optimum oxidation efficiency. A medium pressure UV lamp was compared to a vacuum UV lamp for its efficiency in oxidation of organic carbon to carbon dioxide. While the medium pressure lamp produced a far smaller percentage of its total radiation at the optimum wavelength for oxidation of organic compounds, the greater overall intensity of the medium pressure lamp was shown to be superior for this application. The composition of the capillary was shown to have a considerable effect on the oxidation efficiency. A quartz capillary, internal diameter 0.6 mm, was compared with a PTFE capillary, internal diameter 0.5 mm, for the oxidation of organic carbon by external UV treatment. While peak width, an important consideration in chromatographic resolution, was greater for the larger internal diameter quartz capillary, the lower UV transparency of PTFE combined with the shorter contact time, due to the reduced internal diameter of the capillary, resulted in a less efficient oxidation step using the PTFE capillary. The quartz capillary was therefore chosen for use in the UV/persulfate oxidation step for oxidation of organic carbon to carbon dioxide. Separation of the produced carbon dioxide from the sample stream was achieved by sparging with nitrogen and contacting the gas/liquid mixture with a hydrophobic PTFE membrane, restricting the passage of the liquid while allowing the nitrogen and carbon dioxide gases to pass to the detection system.The only factor influencing this separation was the flow of the nitrogen sparge gas, with a flow of 2 mL min-1[superscript] found to be optimum. Detection of produced carbon dioxide was via a Fourier transform infrared (FTIR) spectrometer with a Iightpipe accessory. The Iightpipe accessory was designed for use as a detector for gas chromatography and the small size of the detector cell was ideal for use with this application. Using the new system described, concentrations of a single peak could be determined with a detection limit of 31 ng and a determination limit of 68 ng. The development of the new OCD allowed characterisation of NOM in terms of its MW distribution and the UV and fluorescence spectral properties of each MW fraction. Further characterisation of MW fractions of NOM from a local groundwater bore was carried out by separation of the fractions by preparative HPSEC, followed by off-line analysis. Preparative HPSEC involved the injection of a pre-concentrated groundwater sample multiple times, using a large scale HPSEC column, then collecting and combining material of identical MW. This allowed each MW fraction of the sample to be further characterised as described in Chapter 5. Preparative HPSEC has only previously been applied to a small number of samples for the concentration and fractionation of NOM, where the structural features of the various MW fractions were studied. In the current research, more extensive studies of not only the chemical characteristics, but also the disinfection behaviour, of the MW fractions were conducted. Separation of the sample was conducted on a large diameter silica-based HPSEC column, with fraction collection based on semi-resolved peaks of the HPSEC chromatogram. Nine MW fractions were collected by this method.After concentration and dialysis to remove the buffer salts in the HPSEC mobile phase, each fraction was re-analysed by analytical HPSEC-UV254[subscript] and showed a single Gaussian shaped peak, indicating discrete MW fractions had successfully been collected. Analysis of the collected MW fractions indicated that 57 % of the organic carbon was in Fractions 3 and 4, with 41 % in Fractions 5-9, leaving only 2 % in Fractions 1 (highest MW) and 2. For each of the nine MW fractions, chorine demand and 7 day trihalomethane formation potential (THMFP) were measured on dilute solutions of the same DOC concentration, and solid state 13[superscript]C NMR spectra were recorded on some of the solid isolates obtained after Iyophilisation of the separate or combined dialysis retentates. The larger MW Fractions 3 and 4 were found to contain a greater proportion of aromatic and carbonyl carbon, and the lower MW Fractions 5 and 6 and Fractions 7-9 contained greater proportions of aliphatic and O-aliphatic carbon, by this technique. Chlorine demand experiments on each individual fraction with a normalised DOC concentration indicated that the largest MW fraction (Fraction 1) had the lowest chlorine demand. It was concluded that material in this fraction may be associated with inorganic colloids and unavailable for reaction with chlorine. Fraction 3 had the highest chlorine demand, just over two times more than the next highest chlorine demand (Fraction 4) and approximately three times the chlorine demand of Fraction 2. The organic material in Fraction 2 was postulated to contain a mixture of the reactive material present in Fraction 3 and the colloidal associated material present in Fraction 1.NMR analysis indicated that the difference between Fraction 3 and Fraction 4 was a reduction in reactive aromatic carbon and hence the lower chlorine demand in the latter fraction. Fractions 5-8 had similar chlorine demands, lower than Fraction 4, while Fraction 9 had a very low chlorine demand similar to that of Fraction 1. For Fractions 5-9, the lower aromatic carbon content most likely resulted in the lower chlorine demand. The 7 day THMFP experiments showed some clear trends, with Fraction 1 and Fraction 2 producing the least amounts of THMs but having the greatest incorporation of bromine. Fractions 3 and 4 produced the greatest concentration of THMs with the lowest bromine incorporation, perhaps as they contained fast reacting THM precursors and the higher chlorine concentrations resulted in greater amounts of chlorinated THMs. Fraction 5 and Fraction 6 produced similar levels of THMs over 7 days to Fractions 7-9 (approximately 75% of the amount formed by Fractions 3 and 4), however, Fractions 7-9 formed these THMs more quickly than Fractions 5 and 6, with slightly greater amounts of bromine incorporation. It was thought that the increased speed of formation was due to the smaller MW of these fractions and a simpler reaction pathway from starting material to formation of THMs, as well as some structural differences. This research marks the first report of significantly resolved MW fractions being isolated and their behaviour in the presence of a disinfectant being determined. While the high MW fractions had the greatest chlorine demands and THMFPs, these fractions are also the easiest to remove during coagulation water treatment processes, as shown in Chapter 3. The lowest MW material formed significant amounts of THMs, and also formed THMs more quickly than other MW fractions.This has important implications from a water treatment perspective, as the lowest MW material is also the most difficult to remove during conventional treatment processes. Solid samples of NOM were isolated from water samples taken from four points at the Wanneroo GWTP using ultrafiltration and subsequent Iyophilisation of the retained fractions, as described in Chapter 6. The sampling points were following aeration (Raw), following treatment by MIEX®, following treatment by MIEX®-C and following treatment by EC. Elemental analysis, FTIR spectroscopy, solid state 13[superscript]C NMR spectroscopy and HPSEC-UV254[subscript]-0CD analysis were used to compare the four isolates. Treatment with MIEX®-C was found to remove the greatest amount of NOM. Additionally, treatment with MIEX®-C was able to remove the largest MW range of NOM, with the remaining material being depleted in aromatic species and having a greater proportion of aliphatic and O-aliphatic carbon. EC treatment completely removed the NOM components above 5000 Da, but NOM below this was not well removed. NOM remaining after the EC train had a lower aromatic content and more aliphatic oxygenated organic matter than the RW. The remaining organic matter after MIEX® treatment contained less aromatic material compared to the RW, but had a greater aromatic content than either of the EC or MIEX®-C samples. HPSEC was a significant analytical technique used throughout this research. Initial optimisation of an HPSEC method was an important development which allowed improved resolution of various MW fractions. The application of this technique and comparison of three detection systems for the study of DOC removal showed, for the first time, the performance of MIEX® treatment at a full scale groundwater treatment facility.The use of various HPSEC detection systems allowed significant characterisation of the MW fractions, more information than had previously been gathered from such a sample set. This work demonstrated the need for OCD when applying HPSEC to the study of NOM. As such, a system was constructed that built on previously developed systems, with the use of a small detector cell enabling detection limits capable of measuring even the most dilute natural and treated water samples. To study the individual MW fractions in detail, preparative HPSEC was applied and, for the first time, the disinfection behaviour of various MW fractions was examined. Interestingly, the lowest MW fractions, acknowledged to be the most recalcitrant to conventional water treatment processes, produced significant quantities of THMs. Also the formation kinetics of THMs from the low MW fractions indicated that THMs were formed as quickly as, or perhaps even at faster rates than from the larger MW fractions. Finally, structural characterisation of NOM at four stages of the Wanneroo GWTP indicated MIEX®-C treatment was superior to EC, of significant interest for the water industry.

Natural organic matter (NOM), ubiquitous in natural water sources, is generated by biogeochemical processes in both the water body and in the surrounding watershed, as well as from the contribution of organic compounds that enter the water as a result of human activity. NOM significantly affects the properties of the water source, including the ability to transport metals, influence the aggregation kinetics of colloidal particles, serve as a food source for microorganisms and act as a precursor in the formation of disinfection by-products (DBPs), as well as imparting a brown colour to the water. The reactivity of NOM is closely tied to its physicochemical properties, such as aromaticity, elemental composition, functional group content and molecular weight (MW) distribution. The MW distribution is an important consideration from a water treatment perspective for several reasons. For example, low MW NOM decreases the efficiency of treatment with activated carbon, and this fraction is thought to be the portion most difficult to remove using coagulation. The efficiency of membranes in the treatment of drinking water is also influenced by the MW distribution of NOM, while some studies have shown that the low MW fraction contributes disproportionately to the formation of bioavailable organic matter, therefore promoting the formation of biofilms in the distribution system. For these reasons, understanding the MW distribution of NOM is important for the treatment of natural waters for use as drinking waters. Optimisation of a high pressure size exclusion chromatography (HPSEC) method for analysis of the MW distribution of NOM in natural waters is described (Chapter 2). Several parameters influencing the performance of HPSEC are tested and an optimised set of conditions illustrated.
These parameters included eluent composition, ionic strength of the sample, flow rate and injection volume. Firstly, it was found that increasing the ionic strength of the HPSEC eluent resulted in less exclusion of NOM from the stationary phase. Stationary phases used in HPSEC contain a residual negative charge that can repel the negatively charged regions of NOM, effectively reducing the accessible pore volume. By increasing the ionic strength, interactions between the stationary phase and eluent enabled a larger effective pore size for the NOM analytes. However, increasing ionic strength of the eluent also resulted in a loss of peak resolution for the NOM portion able to access the pore volume of the stationary phase. Determining the ideal eluent composition required the balancing of these two outcomes. Matching of the ionic strength of the sample with the eluent was also an important consideration. Retention times were slightly lower when the sample ionic strength was not matched with the eluent, especially for the lowest MW material, although the effect on chromatography was minimal. Flow rate had no effect on the resolution of the HPSEC chromatogram for the portion of material able to permeate the pore space of the stationary phase. Changes in the volume of sample injected had a marked effect on the elution profile of the NOM sample. Besides the obvious limitation of detection limit, only minor changes in elution profile were obtained up to an injection volume of 100 µL. Volumes above this value, however, resulted in significant peak broadening issues, as well as an undesirable effect on the low MW portion of detected DOC.
In Chapter 3, high pressure size exclusion chromatography with UV254 [subscript] and on-line detection of organic carbon (HPSEC-UV254[subscript]-OCD) was used to compare the removal of different apparent MW fractions of DOC by two process streams operating in parallel at the local Wanneroo groundwater treatment plant (GWTP). One of these two process streams included alum coagulation (operating in an enhanced coagulation mode (EC) for increased DOC removal) and the other stream included a magnetic ion exchange (MIEX®) process followed by alum coagulation (MIEX®-C). The MIEX® process is based on a micro-sized, macroporous, strong base anion exchange resin with magnetic properties, which has been designed to remove NOM through ion exchange of the anionic sites in NOM. Water was sampled from five key locations within these process streams, and the DOC at each location was characterised in terms of its MW distribution. HPSEC was carried out using three different on-line detector systems, namely OCD, UV absorbance detection at 254 nm, and fluorescence detection (λex[subscript]= 282 nm; λim[subscript] = 353 nm). This approach provided significant information on the chemical nature of the DOC in the various MW fractions. The MIEX®-C process was found to outperform the EC process: these two processes removed similar amounts of high and low MW DOC, but the MIEX®-C process showed greater removal of DOC from the intermediate MW fractions. The two coagulation processes (EC and coagulation following MIEX®) showed good removal of the fractions of highest MW, while the MIEX® process alone was found to remove DOC across all MW fractions.
These results seem to indicate that anionic groups, particularly susceptible to removal with MIEX® treatment, are well distributed across all MW fractions of NOM. In agreement with previous studies, MIEX®-C outperformed EC in the overall removal of DOC (MIEX®-C removed 25 % more DOC than EC). However, 70% of the additional DOC removed by MIEX®-C was comprised of a surprisingly narrow range of medium-high MW fractions. The development of a novel online organic carbon detector (OCD) for use with HPSEC for determining the MW distribution of NOM is described in Chapter 4. With UV absorbance detection, the magnitude of the signal is based on the extinction coefficient of the chromophores in the analytes being investigated; whereas the signal from an OCD is proportional to the actual organic carbon concentrations, providing significantly more information. The development of an online OCD involved the separation of analytes using HPSEC, removal of inorganic carbon species which may interfere with organic carbon determination, oxidation of the organic carbon to carbon dioxide, separation of the produced carbon dioxide from the aqueous phase and subsequent detection of the gaseous carbon dioxide. In the new instrument, following separation of components by HPSEC, the sample stream was acidified with orthophosphoric acid to a concentration of 20 mmol L-1[superscript], resulting in a pH of ≤ 2, in order to convert inorganic carbon to carbon dioxide. This acid dose was found to remove greater than 99 % of inorganic carbon once the acidified sample was passed through a hydrophobic polytetrafluoroethylene (PTFE) membrane allowing the passage of dissolved gases (under negative pressure from a vacuum pump) but restricting the flow of the mobile phase.
Several factors influenced the oxidation of the organic carbon in the next step, including the dose of persulfate, the type and intensity of UV radiation and the composition of the capillary through which the sample stream passes. Through optimisation of this process, it was found that a persulfate dose of 0.84 mmol L-1[superscript] in the sample stream was required for optimum oxidation efficiency. A medium pressure UV lamp was compared to a vacuum UV lamp for its efficiency in oxidation of organic carbon to carbon dioxide. While the medium pressure lamp produced a far smaller percentage of its total radiation at the optimum wavelength for oxidation of organic compounds, the greater overall intensity of the medium pressure lamp was shown to be superior for this application. The composition of the capillary was shown to have a considerable effect on the oxidation efficiency. A quartz capillary, internal diameter 0.6 mm, was compared with a PTFE capillary, internal diameter 0.5 mm, for the oxidation of organic carbon by external UV treatment. While peak width, an important consideration in chromatographic resolution, was greater for the larger internal diameter quartz capillary, the lower UV transparency of PTFE combined with the shorter contact time, due to the reduced internal diameter of the capillary, resulted in a less efficient oxidation step using the PTFE capillary. The quartz capillary was therefore chosen for use in the UV/persulfate oxidation step for oxidation of organic carbon to carbon dioxide. Separation of the produced carbon dioxide from the sample stream was achieved by sparging with nitrogen and contacting the gas/liquid mixture with a hydrophobic PTFE membrane, restricting the passage of the liquid while allowing the nitrogen and carbon dioxide gases to pass to the detection system.
The only factor influencing this separation was the flow of the nitrogen sparge gas, with a flow of 2 mL min-1[superscript] found to be optimum. Detection of produced carbon dioxide was via a Fourier transform infrared (FTIR) spectrometer with a Iightpipe accessory. The Iightpipe accessory was designed for use as a detector for gas chromatography and the small size of the detector cell was ideal for use with this application. Using the new system described, concentrations of a single peak could be determined with a detection limit of 31 ng and a determination limit of 68 ng. The development of the new OCD allowed characterisation of NOM in terms of its MW distribution and the UV and fluorescence spectral properties of each MW fraction. Further characterisation of MW fractions of NOM from a local groundwater bore was carried out by separation of the fractions by preparative HPSEC, followed by off-line analysis. Preparative HPSEC involved the injection of a pre-concentrated groundwater sample multiple times, using a large scale HPSEC column, then collecting and combining material of identical MW. This allowed each MW fraction of the sample to be further characterised as described in Chapter 5. Preparative HPSEC has only previously been applied to a small number of samples for the concentration and fractionation of NOM, where the structural features of the various MW fractions were studied. In the current research, more extensive studies of not only the chemical characteristics, but also the disinfection behaviour, of the MW fractions were conducted. Separation of the sample was conducted on a large diameter silica-based HPSEC column, with fraction collection based on semi-resolved peaks of the HPSEC chromatogram. Nine MW fractions were collected by this method.
After concentration and dialysis to remove the buffer salts in the HPSEC mobile phase, each fraction was re-analysed by analytical HPSEC-UV254[subscript] and showed a single Gaussian shaped peak, indicating discrete MW fractions had successfully been collected. Analysis of the collected MW fractions indicated that 57 % of the organic carbon was in Fractions 3 and 4, with 41 % in Fractions 5-9, leaving only 2 % in Fractions 1 (highest MW) and 2. For each of the nine MW fractions, chorine demand and 7 day trihalomethane formation potential (THMFP) were measured on dilute solutions of the same DOC concentration, and solid state 13[superscript]C NMR spectra were recorded on some of the solid isolates obtained after Iyophilisation of the separate or combined dialysis retentates. The larger MW Fractions 3 and 4 were found to contain a greater proportion of aromatic and carbonyl carbon, and the lower MW Fractions 5 and 6 and Fractions 7-9 contained greater proportions of aliphatic and O-aliphatic carbon, by this technique. Chlorine demand experiments on each individual fraction with a normalised DOC concentration indicated that the largest MW fraction (Fraction 1) had the lowest chlorine demand. It was concluded that material in this fraction may be associated with inorganic colloids and unavailable for reaction with chlorine. Fraction 3 had the highest chlorine demand, just over two times more than the next highest chlorine demand (Fraction 4) and approximately three times the chlorine demand of Fraction 2. The organic material in Fraction 2 was postulated to contain a mixture of the reactive material present in Fraction 3 and the colloidal associated material present in Fraction 1.
NMR analysis indicated that the difference between Fraction 3 and Fraction 4 was a reduction in reactive aromatic carbon and hence the lower chlorine demand in the latter fraction. Fractions 5-8 had similar chlorine demands, lower than Fraction 4, while Fraction 9 had a very low chlorine demand similar to that of Fraction 1. For Fractions 5-9, the lower aromatic carbon content most likely resulted in the lower chlorine demand. The 7 day THMFP experiments showed some clear trends, with Fraction 1 and Fraction 2 producing the least amounts of THMs but having the greatest incorporation of bromine. Fractions 3 and 4 produced the greatest concentration of THMs with the lowest bromine incorporation, perhaps as they contained fast reacting THM precursors and the higher chlorine concentrations resulted in greater amounts of chlorinated THMs. Fraction 5 and Fraction 6 produced similar levels of THMs over 7 days to Fractions 7-9 (approximately 75% of the amount formed by Fractions 3 and 4), however, Fractions 7-9 formed these THMs more quickly than Fractions 5 and 6, with slightly greater amounts of bromine incorporation. It was thought that the increased speed of formation was due to the smaller MW of these fractions and a simpler reaction pathway from starting material to formation of THMs, as well as some structural differences. This research marks the first report of significantly resolved MW fractions being isolated and their behaviour in the presence of a disinfectant being determined. While the high MW fractions had the greatest chlorine demands and THMFPs, these fractions are also the easiest to remove during coagulation water treatment processes, as shown in Chapter 3. The lowest MW material formed significant amounts of THMs, and also formed THMs more quickly than other MW fractions.
This has important implications from a water treatment perspective, as the lowest MW material is also the most difficult to remove during conventional treatment processes. Solid samples of NOM were isolated from water samples taken from four points at the Wanneroo GWTP using ultrafiltration and subsequent Iyophilisation of the retained fractions, as described in Chapter 6. The sampling points were following aeration (Raw), following treatment by MIEX®, following treatment by MIEX®-C and following treatment by EC. Elemental analysis, FTIR spectroscopy, solid state 13[superscript]C NMR spectroscopy and HPSEC-UV254[subscript]-0CD analysis were used to compare the four isolates. Treatment with MIEX®-C was found to remove the greatest amount of NOM. Additionally, treatment with MIEX®-C was able to remove the largest MW range of NOM, with the remaining material being depleted in aromatic species and having a greater proportion of aliphatic and O-aliphatic carbon. EC treatment completely removed the NOM components above 5000 Da, but NOM below this was not well removed. NOM remaining after the EC train had a lower aromatic content and more aliphatic oxygenated organic matter than the RW. The remaining organic matter after MIEX® treatment contained less aromatic material compared to the RW, but had a greater aromatic content than either of the EC or MIEX®-C samples. HPSEC was a significant analytical technique used throughout this research. Initial optimisation of an HPSEC method was an important development which allowed improved resolution of various MW fractions. The application of this technique and comparison of three detection systems for the study of DOC removal showed, for the first time, the performance of MIEX® treatment at a full scale groundwater treatment facility.
The use of various HPSEC detection systems allowed significant characterisation of the MW fractions, more information than had previously been gathered from such a sample set. This work demonstrated the need for OCD when applying HPSEC to the study of NOM. As such, a system was constructed that built on previously developed systems, with the use of a small detector cell enabling detection limits capable of measuring even the most dilute natural and treated water samples. To study the individual MW fractions in detail, preparative HPSEC was applied and, for the first time, the disinfection behaviour of various MW fractions was examined. Interestingly, the lowest MW fractions, acknowledged to be the most recalcitrant to conventional water treatment processes, produced significant quantities of THMs. Also the formation kinetics of THMs from the low MW fractions indicated that THMs were formed as quickly as, or perhaps even at faster rates than from the larger MW fractions. Finally, structural characterisation of NOM at four stages of the Wanneroo GWTP indicated MIEX®-C treatment was superior to EC, of significant interest for the water industry.

Water supply systems aim, among other objectives, to protect public health by reducing the concentration of, and potentially eliminating, microorganisms pathogenic to human beings. Yet, because water supply systems are engineered systems facing variable conditions, such as raw water quality or treatment process performance, the quality of the drinking water produced also exhibits variability. The reliability of a treatment system is defined in this context as the probability of producing drinking water that complies with existing microbial quality standards. This thesis examines the concept of reliability for two physicochemical treatment technologies, conventional rapid granular filtration and ultrafiltration, used to remove the protozoan pathogen Cryptosporidium parvum from drinking water. First, fault tree analysis is used as a method of identifying technical hazards related to the operation of these two technologies and to propose ways of minimizing the probability of failure of the systems. This method is used to compile operators’ knowledge into a single logical diagram and allows the identification of important processes which require efficient monitoring and maintenance practices. Second, an existing quantitative microbial risk assessment model is extended to be used in a reliability analysis. The extended model is used to quantify the reliability of the ultrafiltration system, for which performance is based on full-scale operational data, and to compare it with the reliability of rapid granular filtration systems, for which performance is based on previously published data. This method allows for a sound comparison of the reliability of the two technologies. Several issues remain to be addressed regarding the approaches used to quantify the different input variables of the model. The approaches proposed herein can be applied to other water treatment technologies, to aid in prioritizing interventions to improve system reliability at the operational level, and to determine the data needs for further refinements of the estimates of important variables.

Dricksvatten är en essentiell del av ett hållbart samhälle. Därför är det viktigt att säkerställa säkert dricksvatten genom fungerande vattenreningsverk. En viktig förorening att behandla är NOM, som i sig är ofarligt men som kan producera farliga föroreningar. En teknik som används för behandling av NOM är kolfiltrering. Hur ökad flödeshastighet och ökad kontakttid påverkade kolfiltrens effektivitet undersöktes vid dricksvattenreningsverket Norrvatten. De undersökta parametrarna var partiklar, ultraviolett absorbans vid 254 nm, turbiditet, konduktivitet, fluorescent löst organiskt material, totalt organiskt kol, kemisk syreförbrukning, odlingsbara mikroorganismer och lukt. Tre kolfilter studerades vid olika flödeshastigheter; 190, 220, 250 och 280 L/s under ett dygn var. Samtidigt hade två filter ökad kontakttid på 60 och 76 % under sex veckor, medan ett filter fortsatte med den vanliga flödeshastigheten på 190 L/s. Utgående vatten från filtren analyserades för att se om dessa ändringar hade någon effekt på vattenreningen. Denna preliminära studie fann ingen signifikant effekt på kolfiltreringens rening på grund av ökad flödeshastighet eller uppehållstid. Detta kan vara en indikation på att kolfiltreringen kan hantera en framtida flödesökning och därmed vara en väsentlig del av en framtida expansionen av vattenreningsverket. De tecken som visade på att kolfiltren påverkades av ökningen av flödeshastigheter kunde förklaras av fluktuationer i inkommande vatten och skillnader mellan de olika filtren. I framtiden bör effekten av inkommande vatten studeras i detalj. En mer ingående analys av både inkommande och utgående vatten till kolfiltren bör utföras, där provtagning sker oftare för att bättre förstå fluktuationerna i inkommande föroreningskoncentrationer. Dessutom bör testerna upprepas för att se hur reningen skiljer sig från dag till dag. Hur kolfiltren hanterar ökade flödeshastigheter över längre tidsperioder bör också undersökas vidare.
Drinking water is an essential part of a sustainable society. In the future, the demand for drinking water will increase and contaminants in the water sources are also predicted to increase. Therefore, it is essential to ensure safe drinking water through functioning drinking water treatment plants (DWTPs). One important contaminant to treat is natural organic matter (NOM), which is harmless in itself but can produce harmful products. One technique to use for treating NOM is carbon filters (CFs). The effect of increased flow rate and increased empty bed contact time (EBCT) on the CF efficiency was investigated at a DWTP. The investigated parameters were particles, ultraviolet absorbance at 254 nm, turbidity, conductivity, cultivable microorganisms, fluorescent dissolved organic matter, total organic carbon, chemical oxygen demand, and odour. Three CFs were studied at different flow rates; 190, 220, 250, and 280 L/s for 24 hours each. Additionally, two filters had increased EBCT of 60 and 76 %, while one filter continued with the regular flow rate of 190 L/s for six weeks. Outgoing water from the filters was analysed to see if the change had any effect on the DWTP. This preliminary study did not find any significant effect on the CF treatment caused by increased flow rate or EBCT. This could be an indication that the CFs can handle a future increase in flow rate and thus be an essential part of a future expansion of the DWTP. The indications of CFs being affected by the increase in flow rates for some of the parameters could be explained by fluctuations in incoming water or differences between the separate filters. In the future, a more thorough analysis of both incoming and outgoing water to the CFs should be done, where sampling occurs more frequently to better understand the fluctuations in incoming contaminant concentrations. The measurements should also be repeated to see how the treatment differs from day to day. How the CFs handle increased flow rates over longer time periods should also be investigated further.

The first chapter of diploma thesis discusses about various water processes which remove metals and metalloids compounds from water. A substantial part is devoted to filter materials, which include a new filter material DMI-65. Comprehensive chapter discribes characteristics, proporties and practical application of filter material DMI-65. The next chapter describes the process of pilot testing of material DMI-65 in the water treatment plant in Ivancice. At the end of the diploma thesis, the laboratory test of filter material DMI-65 is described, including the description of particular metals that are removed from the water and the compresion of the filter materiál DMI-65 with other selected filter materials.

Les procédés de traitement par ultrafiltration sont certes largement utilisés pour la production d’eau potable mais leurs performances environnementales restent néanmoins mal connues. Cetravail vise à une meilleure compréhension de l’empreinte environnementale des membranes, ainsi qu’à la proposition et mise en oeuvre de solutions innovantes et pertinentes afin de l’atténuer. Une approche multi-étapes d'écoconception est appliquée aux fibres creuses fabriquées par inversion de phase et utilisées en filtration frontale. Deux modèles paramétrés ontété développés pour évaluer les impacts environnementaux lors des étapes de fabrication et d'utilisation en fonction des conditions opératoires. L’analyse de cycle de vie a mis en évidenceque les conditions opératoires liées au glycérol étaient des leviers d’action intéressants pour l’étape de fabrication. La quasi-exclusivité des impacts environnementaux est toutefois liée à l’étape d’utilisation, pour laquelle la production d’électricité et la fabrication d’hypochlorite de sodium sont les deux principaux contributeurs. L'analyse montre également l'influence du flux de filtration. Des opportunités existent concernant l’utilisation de solvants biosourcés, d’où la stratégie d’amélioration qui consiste à remplacer les solvants d’origine pétrochimique lors de la fabrication membranaire. Un cadre méthodologique basé sur des indicateurs a été proposé afin de rationaliser la fabrication de membrane durable. Des membranes planes biosourcées ont ainsi été obtenues en utilisant le lactate de méthyle comme solvant. Les résultats environnementaux mitigés n'excluent pas pour autant le remplacement de solvant en tant que stratégied'amélioration. Les résultats soulignent la faisabilité et la pertinence de cette approche d'écoconception basée sur la modélisation de procédé et le travail expérimental, et posent lesbases des améliorations futures
Although ultrafiltration treatment processes are widely used for drinking water applications, their environmental performances remain poorly understood. The objectives of this work are to provide understanding of membrane environmental footprint, as well as to suggest and implement relevant innovative solutions for its mitigation. A multiphase ecodesign approach is applied to hollow fibres fabricated by phase inversion and operated in a dead-end mode. The two developed parameterized models evaluate environmental impacts during fabrication and operation as a function of operating conditions. The subsequent Life Cycle Assessment highlights glycerol-related operating conditions as interesting action levers for environmental mitigation of membrane fabrication. However, membrane operation accounts for nearly exclusively all environmental impacts, with electricity production and sodium hypochlorite fabrication as the two main contributors. The analysis also pinpoints the influence of filtration flux. Since opportunities for biosourced solvents exist, substitution of petrochemical solvents during membrane fabrication is chosen as an improvement strategy. A metrics-based methodological framework is suggested to rationalize sustainable membrane fabrication. Biosourced flat membranes using methyl lactate as a solvent have thus been prepared. The mixed environmental scores do not preclude solvent substitution as a relevant improvement strategy. Results highlight the feasibility and relevance of such an ecodesign approach based on process modelling and experimental work, and lay the foundations for further development

Des outils adaptés pour s’attaquer aux problématiques environnementales sont nécessaires mais malheureusement absents de l’industrie. En effet, l’introduction de nouvelles pratiques d’écoconception dans l’industrie des procédés est entravée par le manque de réalisme et de flexibilité des outils associés. Les objectifs principaux de ce travail de recherche étaient le développement d’un outil intégré pour la modélisation de procédés et l’analyse de cycle de vie (PM-LCA), ainsi que la formulation d’une approche méthodologique affiliée pour l’écoconception de procédés. L’outil logiciel et l’approche méthodologique sont appliqués à la production d’eau potable.La revue de la littérature scientifique a permis d’appréhender les efforts de recherche nécessaires. Les principales lignes directrices sont établies en conséquence.L’outil développé, nommé EVALEAU, consiste en une bibliothèque logicielle de modèles de procédés unitaires permettant le calcul d’inventaire de données en fonction de paramètres de procédés. L’outil est embarqué dans le logiciel ACV Umberto® en complément de la base de données Ecoinvent. Uneboîte à outils pour l’analyse de sensibilité, basée sur la méthode de Morris, est implémentée pour l’identification des paramètres de procédés ayant une influence majeure sur les résultats d’impacts environnementaux.L’outil EVALEAU est testé sur deux études de cas - deux usines de production d’eau potable existantes. La fiabilité de l’approche est démontrée à travers la comparaison des calculs de qualité de l’eau, de consommations d’énergie et de matériaux avec les données réelles recueillies sur site. Une procédure d’écoconception est expérimentée sur une chaîne de traitement complexe démontrant ainsi la pertinence des résultats de simulations et l’utilité de l’analyse de sensibilité pour un choix optimal des paramètres opératoires. En conséquence, ce premier outil PM-LCA est censé promouvoir l’introduction de pratiques d’écoconception dans l’industrie de l’eau
Adapted tools for tackling environmental issues are necessary but they are still missing in industry. Indeed, the introduction of ecodesign practices in the process industry is hindered by the lack of realism and flexibility of related tools.The main objectives of this research work were the development of a fully integrated tool for Process Modelling & Life Cycle Assessment (PM-LCA), and the formulation of an affiliated methodological approach for process ecodesign. The software tool and the methodological approach are meant to be applied to water treatment technologies.The literature review leads to a better comprehension of the required research efforts. The main guidelines for the development of the software tool are stated accordingly.The developed tool, named EVALEAU, consists in a library of unit process models allowing life cycleinventory calculation in function of process parameters. The tool is embedded in Umberto® LCA software and is complementary to Ecoinvent database. A sensitivity analysis toolbox, based on theMorris method, was included for the identification of the process parameters mainly affecting the lifecycle impact assessment results.EVALEAU tool was tested through two case studies - two existing drinking water plants. There liability of the modelling approach was demonstrated through water quality simulation, energy and materials inventory simulation, compared with site real data. An ecodesign procedure was experienced on a complex water treatment chain, demonstrating the relevance of simulation results and the usefulness of sensitivity analysis for an optimal choice of operation parameters.This first developed PM-LCA tool is dedicated to foster the introduction of ecodesign practices in the water industry

Removing dissolved organic matter (DOM) from the source water is critical for the drinking water treatment process. The low molecular weight hydrophilic fraction of DOM is generally recalcitrant to removal by coagulation, and the DOM bypassing the coagulation/filtration stages of treatment will likely react with the disinfecting agent at the end of the treatment process, leading to the formation of potentially carcinogenic disinfection by products (DBPs) such as trihalomethanes (THMs). Each specific fraction of DOM reacts with a particular disinfecting agent to form different DBPs; some with higher toxicity and carcinogenicity than others. Understanding the DBPs formation pathways, however, is a difficult task since DOM present in the source water are likely to be highly degraded compounds that differ from each other, forming a mixture of diverse molecules which are extremely challenging to individually characterise. Hence, there is a need for monitoring certain fractions of DOM, such as humic acids, by tracking down DOM characteristics and concentration levels in source waters. DOM characterisation techniques can be divided into three groups. The first group investigates the abundance and nature of structural units, providing detailed structural information. The second group looks into the chemical behaviour of DOM, its molecular weight, molecular size, distribution, and hydrophobicity-hydrophilicity. It also focuses on its polymeric nature and ability to provide good molecular separation. The third group measures the fluorescence signal of DOM in situ, without directly scrutinising chemical identities of functional groups or molecules. However, the methods used in the first two groups are complicated and time-intensive, making them unsuitable for remote online monitoring of DOM characteristics. In contrast, the currently available fluorescence probes provide a simple, sensitive, rapid, non-invasive way of in-situ estimation of the fluorescent DOM (fDOM). Despite the potential beneficial applications of this relatively new technology, field fDOM measurements are subject to interferences caused by changes in temperature, turbidity, pH, salinity and inner filter effect (IFE). This often makes probe readings unreliable; as a result, they are rarely used by water treatment plant operators. Thus, accurate and reliable compensation models should be designed and applied to raw fDOM readings collected by fluorescence probes, in order to make them a useful decision support tool for water treatment plant operators. This study introduces a comprehensive, transferable methodological framework for scientists and water professionals to model fluorescence site-specific quenching on fDOM probe readings caused by temperature, suspended particles and the IFE. The compensation model was developed and validated for an Australian subtropical reservoir. Three other Australian reservoirs were also investigated to investigate the role that particle size distribution plays on light scattering, and molecular weight links to fDOM signal intensity. Findings revealed that quenching due to turbidity and IFE effects was best predicted by threshold autoregressive models. Raw fDOM probe measurements were validated as being more reliable if they were systematically compensated using the proposed procedure. The developed fDOM compensation procedure must consider the instrument features (i.e. wavelength broadband and responsiveness) and site-specific conditions (i.e. DOM characteristics and suspended particles). A finding of particular interest was that the compensated fDOM readings had a high correlation with the low (< 500Da) molecular weight fraction of the DOM, which is more recalcitrant to removal by coagulation. As a consequence there is potential to use fDOM probes to provide real-time, in-situ information on DOM properties in freshwater systems, which will enable water treatment plants operators to optimise the coagulation process.
Thesis (Masters)
Master of Philosophy (MPhil)
School of Eng & Built Env
Science, Environment, Engineering and Technology
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Fältstudien gjordes för att utreda om det var möjligt att använda renat, filtrerat avloppsvatten för polymerberedning och i längden även som övrigt processvatten på Ellinge reningsverk. Testerna utfördes i fullskala med både vatten från mellansedimenteringen och slutsedimenteringen. Genom omfattande provtagningar och analysering av resultaten visade det sig vara en fungerande metod utan negativ påverkan på polymerlösningen och slamavvattningen. Det krävs dock mer arbete och ytterligare reningssteg såsom desinficering för att implementera det renade avloppsvattnet på hela vattensystemet.
The field study was done to investigate whether it was possible to use purified, filtered wastewater for polymer preparation and in the long run also as other process water at Ellinge treatment plant. The tests was performed in full scale with both water from the intermediate sedimentation and the final sedimentation. Through extensive sampling and analysis of results, it proved to be a working method without a negative impact on the polymer solution and sludge dewatering. However, more work and addiotional purification steps such as disinfection are required to implement the treated wastewater on the entire water system

Phytoplankton blooms compromise the quality of freshwater ecosystems and the efficient processing of water by treatment works worldwide. This research aims to determine whether in-situ filamentous biofiltration processes mediated by living roots and synthetic filters as media can reduce or remove the phytoplankton loading (micro-algae and cyanobacteria) prior to a potable water treatment works intake. The underlying biofiltration mechanisms were investigated using field and laboratory studies. A novel macroscale biofilter with three plant species, named the "Living-Filter", installed in Farmoor II reservoir, UK, was surveyed weekly for physicochemical and biological variables under continuous flow conditions during 17 weeks. The efficiency of a mesoscale biofilter using the aquatic plant Phalaris arundinacea and synthetic filters, was tested with Microcystis aeruginosa under continuous flow conditions and in batch experiments. The 'simultaneous allelochemical method' was developed for quantifying allelochemicals from Phalaris in aqueous samples. Microscale studies were used to investigate biofilter allelochemical release in response to environmental stressors and Microcystis growth inhibition in filtered and unfiltered aqueous root exudate. Results demonstrate that the removal of phytoplankton biomass by physical mechanisms has a removal efficiency of ≤45% in the "Living-Filter" (filamentous biofilter plus synthetic fabric) and that the removal of Microcystis biomass using only biofilters was 25%. Chemical mechanisms that reduce Microcystis cell numbers are mediated by allelochemicals released from biofilter roots. Root exudate treatments on Microcystis revealed that Microcystis growth is inhibited by allelochemicals, not by nutrient competition, and that protists and invertebrates play a role in removing Microcystis. Filamentous biofilters can remove phytoplankton biomass by physical, chemical and biological mechanisms. Biofilters and synthetic filters in combination improve removal efficiency. Application of macroscale biofilters prior to potable water treatment works benefits the ecosystem. Plant properties, biofilter size to surface water ratio, and retention time must be considered to maximise the benefits of biofiltration processes.

Thesis (MScEng)-- Stellenbosch University, 2013.
ENGLISH ABSTRACT: The objective of this research was to obtain clean drinkable water from treated sewage effluent by using a solar-powered distillation cycle. Technologies and concepts were borrowed from the solar desalination industry to propose a unique circular distillation cell design. From the design, a specific mathematical correlation was developed to predict the distillate mass flow rate by using only evaporation and condensation temperature as inputs. This model was incorporated into a simulation model built using Transient System Simulation software. Long-term simulations were carried out to determine the operating capabilities of the design. A prototype was successfully constructed and operated. Experimental results indicated good agreement with the mass flow rate mathematical correlation. Water quality levels were tested against the South African National Standard 241 national drinking water quality standard. Four quality parameters are outside acceptable levels. Evidence suggested that acceptable quality levels could be reached. The circular distillation cell design is a major contribution made by this research. Another contribution is the simulation model capable of predicting an output for different locations. Finally, the proposed prototype is potentially a very valuable device contributing towards the reduction of consumer demand in terms of water and energy as well as the household load on the wastewater treatment system.
AFRIKAANSE OPSOMMING: Die doel van hierdie tesis is om te beskryf hoe behandelde rioolwater deur middel van ’n son aangedrewe distillasiesisteem gesuiwer kan word om drinkbare water as eindproduk te lewer. Die nodige tegnologieë en konsepte is oorgeneem uit kommersiële sonaangedrewe ontsoutingsisteme om met ’n unieke ontwerp voorendag te kom wat uit ’n sirkelvormige natuurlike konveksie distillasiesel bestaan. Met behulp van hierdie ontwerp is ’n wiskundige korrelasie ontwikkel om die gesuiwerde water se massavloei te bepaal. Slegs die verdampings- en kondensasietemperature word as insetwaardes gebruik om die massavloei te bereken. ’n Simulasiemodel is met behulp van die Transient System Simulation programmatuur gebou. Die wiskundige korrelasie is by die simulasiemodel geïnkorporeer om langtermynsimulasies te kan uitvoer. Voorts is ’n demonstrasiemodel suksesvol gebou en aangedryf. Eksperimentele resultate toon goeie ooreenstemming met die simulasieresultate. Die gesuiwerde water se gehalte is met die nationale SANS 241 drinkwaterstandaard as maatstaf getoets. Slegs vier gehalteparameters val buite die aanvaarbare vlakke, hoewel dit blyk dat hierdie elemente wel tot aanvaarbare vlakke verlaag kan word. Hierdie navorsing se grootstet bydrae is die ontwerp van die unieke sirkelvormige distillasiesel. ’n Bykomende bydra is die aanpasbaarheid van die simulasiemodel sodat dit produksievermoë op verskillende plekke kan voorspel. Die demonstrasiemodel is ’n potensieel waardevolle ontwerp wat kan bydra tot die verlaging in verbruikersaanvraag na water en energie. ’n Ontwerp van hierdie aard kan die las wat huishoudings op suiweringaanlegte vir rioolwater plaas, verlig.

This diploma thesis deals with the efficiency of removal of pharmaceuticals from drinking water by selected adsorption materials. The first part describes sources of pharmaceuticals in drinking water and possible ways of contaminating water by pharmaceuticals. Subsequently, the pharmaceuticals most commonly found in the environment - nonsteroidal anti-inflammatory drugs, antibiotics, psychiatric drugs and sex hormones - are described in more detail. Next, the thesis describes the processes used for removal of pharmaceuticals. These are activated carbon adsorption, membrane processes and advanced oxidation processes. The last chapter of the theoretical part of the thesis deals with water treatment plants, where the technologies for removing drugs are already in operation. In the practical part of this thesis an experiment was performed and evaluated, for a purpose of comparing the efficiency of selected sorption materials in the removal of diclofenac from water. Filtrasorb F100, Bayoxide E33 and GEH were used.

The diploma thesis deals with micro-fuels in drinking water sources and their subsequent removal. In the thesis mainly pesticides and pharmaceuticals are described. The reader is first introduced to the most common pesticides occurring in water and their consumption. Drugs are described in a similar context. In addition, there are practical studies on the occurrence, degradation and removal of micro-pollutants from water. The final thesis is a laboratory experiment dealing with the removal of salicylic acid from water by filtration through the filtration material Bayoxide E33 and activated carbon. The thesis describes the procedure and results of the experiment.

De senaste årtiondena har en ökning av naturligt organiskt material (NOM) observerats i ytvatten i norra Europa och Nordamerika. NOM i vattnet innebär utmaningar för vattenverk som använder ytvatten i dricksvattenproduktionen då det kan ge upphov till lukt, smak och färg och svårigheter i driften. För att åtgärda och förebygga problemen behövs mer kunskap om NOM samt hur kvantiteten och sammansättningen förändras i olika reningsprocesser. Vid Hofors vattenverk används råvatten från sjön Hyen i dricksvattenproduktionen. Driftstörningar upplevs i perioder då råvattnets färgtal (mått på halten NOM) är högt. Därför undersöktes det hur väl den nuvarande reningsprocessen vid Hofors vattenverk fungerar med avseende på avskiljning av NOM samt vilken typ av NOM som avskiljs. Resultaten jämfördes med pilotförsök med direktfällning på ultrafiltermembran för att se om detta kan ge bättre avskiljning. Olika analysmetoder, absorbans, fluorescens och mätning av löst organiskt kol (DOC), användes för att avgöra kvantitet och karaktär på NOM i vattenproverna. Även eventuell förekomst av trend i råvattnets färgtal undersöktes. Likt i många andra ytvatten har färgtalet i Hyen har ökat de senaste åren (1997-2015). Råvattnet är svårfällt och innehåller en blandning av olika NOM-fraktioner. Huvudsakligen avskiljs humuslikt, alloktont NOM i Hofors vattenverk. Avskiljningen var störst i första reningssteget, direktfällning på sandfilter. Förändringen i efterföljande reningssteg, kolfilter samt desinfektions- och pH-höjande steg, var dock svår att bestämma till följd av mycket små förändringar och motsägande analysresultat. Tre ultrafiltermembranförsök gav liknande avskiljningsresultat som sandfilter, men i två av fallen är det troligt att igensättning av membranen spelade in. Det krävs ytterligare försök för att säkert uttala sig om huruvida ultrafiltermembran är en teknik som är lämplig att använda vid Hofors vattenverk i framtiden för avskiljning av NOM.
In recent decades, an increase in natural organic matter (NOM) has been observed in surface waters in Northern Europe and North America. NOM in the water poses challenges for water treatment plants (WTP) using surface water in the drinking water production. It can cause odor, taste and color of the water and cause difficulties in the treatment process. To prevent all these problems, more information about NOM and how the quantity and composition changes in various treatment processes is needed. At Hofors WTP, raw water from the lake Hyen is used in the production of drinking water. Disruptions in running the process have been experienced in periods when the raw water color (measure of the NOM content) has been high. In this thesis, it was investigated how well the current treatment process at Hofors WTP works with respect to the separation of NOM and what type of NOM that is separated. The results were compared with pilot tests with direct filtration using an ultrafilter membrane to see if this can provide better separation. Various analytical methods as absorbance, fluorescence and measurement of dissolved organic carbon (DOC) were used to quantify and determine the composition of NOM in the water samples. It was also examined whether there is a trend in the raw water color. As in many other surface waters the color of the water has increased in Hyen in recent years (1997-2015). The raw water contains a mixture of different NOM fractions and the character indicates difficulties in removing DOC by coagulation and flocculation. It is primarily the humic like, allochtonous NOM that is separated in the treatment process with the greatest separation in the first treatment step, direct filtration with sand filter. What happens in the subsequent treatment steps, carbon filter, disinfection and pH-raising step, was however unclear due to small changes and inconsistent analysis results. Three experiments with ultrafilter membrane yielded similar results as sand filters, but in two of the cases it is likely that clogging of the membranes contributed. Further membrane pilot tests are needed to be sure whether ultrafilter membrane is a is suitable technique to use at Hofors WTP in the future for separation of NOM.

There is a current lack of accurate tools to determine the concentration of cyanobacteria in situ.  Besides, cyanobacterial blooms have to be carefully monitored in reservoirs as they are more frequent because of climate change and can lead to potential released of toxins, along with other components. This project investigates the possible use of fluorescent probes to measure the concentration of different types of organic matter released by the algae. Three different species of toxic cyanobacteria were chosen to carry out this research as they are representative of the local harmful blooms found across Australia. Furthermore, the efficiency of two different chemicals (powdered activated carbon, also known as PAC, and alum) used in drinking water treatment plants were investigated, in order to determine a method for automatic dosage adjustment in water treatment plant. The organic matter was characterized by LC-OCD and fluorescence spectroscopy and statistical analysis such as principal component analysis was performed on the generated data. General characterization of the different species was firstly performed and globally, similar comportments were observed among the three cyanobacteria species. There is indeed a general increase in the release of organic material throughout the cell’s growth phase. Results from the jar tests showed that PAC mainly targeted humic-like substances and building blocks, which are middle size particles. The average removal rate obtained was 40µg/L per mg/L of PAC added into the water. Therefore, there is indication that the decreased efficiency for the removal of the taste and odor compounds observed in certain plants can be partially attributed to direct competition of organic matter adsorption onto PAC instead of a blockage of the PAC pores by larger particles. On the other hand, alum was able to remove large particles, particularly biopolymers and also humic-substances. However, a great increase of the low molecular weight molecules at very high doses of alum was seen, which suggest that a too high dose of alum is toxic for the algae cells. Based on the bench scale testing the recommended dose of 50 mg/L seems to be optimum for the studied water treatment plant. Specific ultraviolet absorbance and dissolved organic carbon measurements were also investigated and good correlations were found between the concentration of humic-like substances and absorbance, confirming that they are good measure to assess the content of organic matter in the water. However, as the slope coefficient of the linear trend varied between the species, it was not possible to obtain a common conversion factor for all the species. Finally, one fluorophore was found in common to all the samples and is characterized by the excitation-emission wavelength: 240/440 nm. Correlations with the chromatography’s results were investigated and this component seems to match the biopolymers and humic-like substances concentrations. Furthermore, its intensity decreases continuously with the addition of PAC whereas a drop was observed at the lower doses of alum. In regards on these findings, a method for automatic chemicals dosing from the fluorescence measures was proposed.
Detta examensarbete handlar om hur dricksvattenkvalitet kan kontrolleras och övervakas i vattenreningsverk. Nu existerar  inte någon exakt metod för att bestämma koncentrationen av cyanobakterier i vatten då det finns många olika arter. Men det är viktigt att övervaka algers tillväxt in i vattenreningsverk för de kan släppa ut skadliga ämnen till dricksvattnet. De tre arter som studerats i detta projekt är giftiga. Det organiska materialet i råvattnet kan också blockera membranporer eller leda till n biprodukter, som är cancerframkallande. Till sist konkurrerar några organiska substansen med smak- och luktföreningar för adsorptionsställena hos det pulverformiga aktiverade kolet. Därför är smaken och luktföreningarna inte väl borttagna, vilket leder till kundernas klagomål. Cyanobakterier måste övervakas noggrant.                            För att bestämma biologisk och kemisk egenskap hos vatten används flera tekniker för närvarande. I examensarbetet har undersökningar med vätskekromatografi och fluorescensteknik företagits. Kromatografi användes för att klassificera den organiska substansen i mindre grupper: biopolymerer, humus substanser, byggstenar och neutralmolekyler med låg molekylvikt (LMVN). Statistisk analys med R, inklusive huvudkomponentanalys företogs på insamlade data. Fluorescensdata registrerades också och visas i en excitationsutsläppsmatris.                            Experimenten reproducerade en behandlingsprocess och undersökte effektiviteten hos två kemikalier: pulveriserat aktivt kol (PAK) och alun. Resultaten visade att humusämnen   och dess byggstenar var väl borttagna av PAK medan även biopolymerer och humusämnen var väl bortagna av alun. Emellertid var en för hög dos av alun skadlig eftersom det ledde till en ökad frisättning av LMVN. I synnerhert kunde PAK ta bort 40µg/L av både humusämnen och dess byggstenar per mg/L av PAK tillagd. Det föreslår att de är de viktigaste konkurrenterna och att endast direkt konkurrens för adsorptionsställena sker. Om det fanns blockeringsfenomen, skulle det också finnas en minskning för biopolymererna. Den optimala doseringen av alun som bestämdes för det undersökta vattenreningsverket var 50 mg/L. Det kunde ta bort 60-70% av biopolymerer och 40-50% av humusämnen.                            Specifik ultraviolett absorbans och fluorescens registrerades. Båda visade riktigt bra korrelationer med humusämnen, vilket gör de till bra verktyg för att bedöma vattenkvaliteten. Men det kräver fortfarande att arten av cyanobakterie urskiljs eftersom koefficientens lutningar var olika. De kan därför vara ett verktyg för att mäta koncentrationen av organisk material, men arten måste vara känd. Fluorescencedata visade en topp vid 440 nm. En parallellfaktoranalys utfördes på data och endast en komponent hittades gemensam i alla prover. Därför studerades den maximala fluorescensintensiteten hos denna komponent. Å ena sidan kunde vi observera en kontinuerlig minskning av intensiteten när PAK tillsattes. Det är därför möjligt att veta hur man justerar den kemiska doseringen från fluorescensintensiteterna. I slutet av examensarbetet föreslås en metod för automatisk kemisk dosering. Fluorescensprober kan ännu inte exakt indikera cellkoncentrationen. Men med flera sonder som riktar sig till olika våglängder kan de redan vara till stor hjälp för styrning vid vattenverk.

The provision of clean drinking water typically involves treatment processes to remove contaminants. The conventional process involves coagulation with hydrolysing metal salts, typically of aluminium (‘alum’) or trivalent iron (‘ferric’). Along with the product water this also produces a waste by-product, or sludge. The fact of increasing sludge production — due to higher levels of treatment and greater volume of water supply — conflicts with modern demands for environmental best practice, leading to higher financial costs. A further issue is the significant quantity of water that is held up in the sludge, and wasted.
One means of dealing with these problems is to dewater the sludge further. This reduces the volume of waste to be disposed of. The consistency is also improved (e.g. for the purpose of landfilling). And a significant amount of water can be recovered. The efficiency, and efficacy, of this process depends on the dewaterability of the sludge.In fact, good dewaterability is vital to the operation of conventional drinking water treatment plants (WTP’s). The usual process of separating the particulates, formed from a blend of contaminants and coagulated precipitate, relies on ‘clarification’ and ‘thickening’, which are essentially settling operations of solid–liquid separation.WTP operators — and researchers — do attempt to measure sludge dewaterability, but usually rely on empirical characterisation techniques that do not tell the full story and can even mislead. Understanding of the physical and chemical nature of the sludge is also surprisingly rudimentary, considering the long history of these processes.
The present work begins by reviewing the current state of knowledge on raw water and sludge composition, with special focus on solid aluminium and iron phases and on fractal aggregate structure. Next the theory of dewatering is examined, with the adopted phenomenological theory contrasted with empirical techniques and other theories.The foundation for subsequent analyses is laid by experimental work which establishes the solid phase density of WTP sludges. Additionally, alum sludges are found to contain pseudoböhmite, while 2-line ferrihydrite and goethite are identified in ferric sludges.
A key hypothesis is that dewaterability is partly determined by the treatment conditions. To investigate this, numerous WTP sludges were studied that had been generated under diverse conditions: some plant samples were obtained, and the remainder were generated in the laboratory (results were consistent). Dewaterability was characterised for each sludge in concentration ranges relevant to settling, centrifugation and filtration using models developed by LANDMAN and WHITE inter alia; it is expressed in terms of both equilibrium and kinetic parameters, py(φ) and R(φ) respectively.This work confirmed that dewaterability is significantly influenced by treatment conditions.The strongest correlations were observed when varying coagulation pH and coagulant dose. At high doses precipitated coagulant controls the sludge behaviour, and dewaterability is poor. Dewaterability deteriorates as pH is increased for high-dose alum sludges; other sludges are less sensitive to pH. These findings can be linked to the faster coagulation dynamics prevailing at high coagulant and alkali dose.Alum and ferric sludges in general had comparable dewaterabilities, and the characteristics of a magnesium sludge were similar too.Small effects on dewaterability were observed in response to variations in raw water organic content and shearing. Polymer flocculation and conditioning appeared mainly to affect dewaterability at low sludge concentrations. Ageing did not produce clear changes in dewaterability.Dense, compact particles are known to dewater better than ‘fluffy’ aggregates or flocs usually encountered in drinking water treatment. This explains the superior dewaterability of a sludge containing powdered activated carbon (PAC). Even greater improvements were observed following a cycle of sludge freezing and thawing for a wide range of WTP sludges.
Further aspects considered in the present work include deviations from simplifying assumptions that are usually made. Specifically: investigation of long-time dewatering behaviour, wall effects, non-isotropic stresses, and reversibility of dewatering (or ‘elasticity’).Several other results and conclusions, of both theoretical and experimental nature, are presented on topics of subsidiary or peripheral interest that are nonetheless important for establishing a reliable basis for research in this area.
This work has proposed links between industrial drinking water coagulation conditions, sludge dewaterability from settling to filtration, and the microstructure of the aggregates making up that sludge. This information can be used when considering the operation or design of a WTP in order to optimise sludge dewaterability, within the constraints of producing drinking water of acceptable quality.

Household water treatment technologies provide an interim solution to drinking water provision in areas which are not yet serviced by a continuous piped connection to a communal treated source. This is a critical problem in Amerindian communities in the Guyanese hinterland region, where remote location and low population density make improving environmental health infrastructure challenging. Biosand filtration is one promising household water treatment technology available for this purpose. The overall goal of this research was to better understand, and thus improve, the biosand filter for field operation. A field study was performed in the Amerindian community of St. Cuthbert's, Guyana. A questionnaire was implemented to determine risk factors for diarrhoeal disease, and water samples were taken from creeks and standpipes in the village and from stored drinking water in households. Serving drinking water by scooping from a bucket as opposed to pouring or using a tap or spigot was found to be a risk factor for illness, while having water piped to the household was associated with lower diarrhoeal disease rates. Post-collection water contamination was found to cause a significant decline in drinking water quality. Adoption and sustained use of biosand filters were compared to two other prominent household water treatment methods, that being the addition of hypochlorite solution and use of a safe water storage container, and ceramic candle filtration. It was found that in St. Cuthbert's bios and filters had moderate adoption (36%) but usage was not sustained (4%). Closing interviews revealed that people found the filters too large and heavy, did not trust them, and found them too difficult to use. The issue of the biosand filter's size and ease of use could be partially mitigated if it were possible to reduce the height of the sand column in the filter. The filter would also be easier to use if it was not necessary to add water every day. Experiments on laboratory columns representing biosand filters determined that although the sand layer in the filters was 55 cm deep, there is little additional benefit to each centimeter over 30 cm of filter depth, making a significant height reduction possible without compromising filter performance. Further column experiments determined that the common field practice of extending residence periods of biosand filters from the recommended one day to two or three days did not lead to a statistically significant reduction in the filter's ability to remove E. coli, but did lead to anaerobic conditions within the filter and a modified nitrogen profile in filter effluent. This may impact the taste of the filtered water. In cases where influent water has high initial nitrogen content this could lead to an exceedance of World Health Organization guidelines for nitrate and nitrite in drinking water. Although the design of biosand filters was based on the theory that a low standing head would cause intermittent operation of slow sand filters to match that of continuous operation, this research found that continuous operation of the biosand filter led to significantly improved removal of bacterial and viral indicators (3.7 log10 versus 1.7 log10 for E. coli, and 2.3 log10 versus 0.9 log10 for bacteriophage MS2).
Les technologies de traitement de l'eau à domicile offrent une solution temporaire pour alimenter en eau potable les zones non encore reliées à un réseau d'apport et de traitement de l'eau communautaire. C'est un problème critique pour les communautés de l'arrière-pays montagneux de la Guyane, où l'isolation géographique et la faible densité démographique rendent l'amélioration des infrastructures hydriques et sanitaires difficile. Le filtre à biosable est une technologie prometteuse pour le traitement de l'eau à domicile qui serait disponible pour pallier ces contraintes. L'objectif de cette recherche a été de mieux comprendre et d'améliorer le filtre à biosable pour son opération sur le terrain. Une étude sur le terrain, incluant la distribution des questionnaires dans la communauté et la prise d'échantillons d'eau, a été réalisée dans la communauté de St Cuthbert's en Guyane. Puiser de l'eau potable directement d'un sceau avec un récipient improvisé par opposition à avoir accès à de l'eau à partir d'un robinet s'est avéré comme étant un facteur à risque pour tomber malade. En revanche, l'accès à l'eau courante au domicile amenée par un réseau de tuyaux a été associé à des taux de maladies diarrhéiques plus faibles. La contamination de l'eau après sa collecte initiale s'est avérée comme étant un facteur causant une baisse significative de la qualité de l'eau potable. L'adoption et l'utilisation à long terme des filtres à biosable ont été comparées à celles de deux autres technologies répandues: l'ajout dans l'eau d'une solution hypochlorique combiné à l'utilisation de récipients sécuritaires d'entreposage de l'eau et la filtration à base de bougies céramiques. L'étude a montré que les filtres à biosable ont connu un taux d'adoption modéré (36%) mais que leur utilisation n'a pas été à long terme (4%). Des entrevues de fin d'étude ont indiqué que les habitants de ont trouvé les filtres à biosable larges et lourds, qu'ils ne leur ont pas fait confiance et, qu'ils ont trouvé leur utilisation difficile. Le problème des dimensions du filtre à biosable et de sa facilité d'utilisation pourrait être atténué s'il était possible de réduire la hauteur de la colonne de sable dans le filtre. Il serait aussi plus facile d'utiliser le filtre s'il n'était pas nécessaire d'y ajouter de l'eau chaque jour. Des essais en laboratoire ont déterminé que, même si la couche de sable dans le filtre a une profondeur de 55 cm, les bénéfices pour chaque centimètre additionnel de sable au-dessus de 30 cm sont minimes. Cela permettrait une réduction significative de la hauteur du filtre sans compromettre sa performance. D'autres essais ont déterminé que la pratique usuelle sur le terrain de prolonger le temps de résidence de l'eau dans les filtres à biosable, de la période recommandée d'un jour à deux ou trois jours, ne conduit pas à une diminution significative de la capacité du filtre à enlever les E. coli. Toutefois, cette pratique conduit à des conditions anaérobiques à l'intérieur du filtre et à un profil d'azote modifié dans l'effluent du filtre à cause de la nitrification. Cela pourrait avoir un impact sur le goût de l'eau filtrée. Dans les cas, où l'eau utilisée a un contenu initial d'azote élevé, les conditions anaérobiques pourraient conduire à un dépassement des recommandations de l'Organisation mondiale de la santé concernant le nitrate et le nitrite dans l'eau potable. La conception initiale des filtres à biosable a été basée sur la théorie que le maintien d'une charge hydraulique minimale permettrait aux filtres à sable lent opérant par intermittence de performer aussi bien que ceux opérant en continue. Toutefois, cette recherche a montré que l'opération continue des filtres à biosable a permis d'améliorer significativement la diminution des indicateurs bactériens et viraux (3.7 log10 versus 1.7 log10 pour E. coli, et 2.3 log10 versus 0.9 log10 pour MS2 bactériophage) par rapport aux filtres à sable lent à opération intermittente.

6 pp.
1. Drinking Water Wells; 2. Private Water Well Components; 3. Do Deeper Wells Mean Better Water; 4. Maintaining Your Private Well Water System; 5. Private Well Protection; 6. Well Water Testing and Understanding the Results; 7. Obtaining a Water Sample for Bacterial Analysis; 8. Microorganisms in Private Water Wells; 9. Lead in Private Water Wells; 10. Nitrate in Private Water Wells; 11.Arsenic in Private Water Wells; 12. Matching Drinking Water Quality Problems to Treatment Methods; 13. Commonly Available Home Water Treatment Systems; 14. Hard Water: To Soften or Not to Soften; 15. Shock Chlorination of Private Water Wells
This fact sheet is one in a series of fifteen for private water well owners. The one- to four-page fact sheets will be assembled into a two-pocket folder entitled Private Well Owners Guide. The titles will also be a part of the Changing Rural Landscapes project whose goal is to educate exurban, small acreage residents. The authors have made every effort to align the fact sheets with the proposed Arizona Cooperative Extension booklet An Arizona Well Owners Guide to Water Sources, Quality, Testing, Treatment, and Well Maintenance by Artiola and Uhlman. The private well owner project was funded by both the University of Arizonas Water Sustainability Program-Technology and Research Initiative Fund and the USDA-CSREES Region 9 Water Quality Program.

Abstract A survey involving 181 water treatment plants across 7 provinces of South Africa: Mpumalanga, Limpopo, North West, Free State, KwaZulu-Natal, Eastern Cape and Western Cape was undertaken to identify the challenges facing small water treatment plants (SWTPs) in South Africa . Information gathered included ownership and design capacity of the plants, water sources, and various methods of disinfection, equipment currently employed and performance of the treatment plants. In general, the majority (over 80%) of the SWTPs surveyed in the designated provinces were owned by the district municipalities. The designed capacities of these plants varied between 1 and 60 Mℓ/d; the smallest capacity was 100 m3/d and the largest 120 Mℓ/d. The small water treatment plants abstracted their raw water from either surface or groundwater or a combination of both water sources with greater preponderance for surface water sources (over 86%). Water treatment practices were noted to be the conventional types mainly coagulation, flocculation, sedimentation, filtration and disinfection. Two types of coagulants namely polyelectrolyte (66%) and alum (18%) were commonly used by the water treatment plants across the provinces studied. Rapid gravity filtration, pressure filter and slow sand filtration systems accounted for 60%, 23% and 9% of the filtration systems across the provinces, respectively. The predominant types of disinfectants employed were chlorine gas (69%) followed by sodium (15%) and calcium (14%) hypochlorite. Over 50% of the various SWTPs did not comply with the SANS 241 Class I (< 1 NTU) and Class II (1 to 5 NTU) recommended turbidity values. The recommended target range of 0.3 to 0.6 mg/ℓ free chlorine residual concentrations at the point of use was not always met by 40% of the plants. Seventy percent of the SWTPs complied with the SANS 241 criteria of microbiological safety of drinking water vis-à-vis total and faecal coliforms. Operational problems affecting the efficiency of small water treatment plants included: inability to appropriately determine the flow rate, chemical dosage and turbidity, lack of chlorine residual at the point of use and lack of water quality monitoring. To produce safe drinking water, appropriate operational practices must be implemented in all small water treatment plants.

Several electrochemical processes are modeled at process levels and atomic scales. Processes are presented for acid generation and ion exchange media regeneration, along with corresponding process models. Transport and reaction processes in individual ion exchange beads are also modeled. Acids of mild strength (pH = ~1-2) are generated from electrolyte solutions and their strength is effectively modeled as a function of time. The regeneration of ion exchange media is also modeled, to close agreement with measurements, and the process model is reconciled with a model for solute flux from an individual ion exchange bead. Together, the models show that the "gentle" regeneration process is controlled by the plating rate. Processes interior to the particle are controlled by diffusion, but all processes are faster than the characteristic time for plating. In a separate process, an electrochemical method is used to produce hypochlorite for disinfection. The process generates perchlorate as a toxic byproduct. Density function theory is used to construct an atomic-scale model of the mechanism for producing perchlorate, as well as the aging of the boron-doped diamond anode used in the process. The mechanism shows that the boron-doped diamond surface plays an important role in chemisorbing and stabilizing radicals of oxychlorine anions, allowing the radicals to live long enough to react and form higher ions like perchlorate. Wear mechanisms that occur on the anode are shown to oxidize and etch the surface, changing its chemical functionality over time. As the surface ages, the overpotential for water oxidation is decreased, decreasing the efficiency of the electrode.

"The goals of this study were (1) to evaluate the impacts of pesticides used for mosquito control on drinking water and (2) to investigate the removal of permethrin from water using activated carbon. A review of current literature on pesticide usage, toxicity, occurrence in the environment, and treatment techniques to remove pesticides from drinking water was conducted. The focus of the literature review was on pesticides used for mosquito control. Permethrin is a synthetic pyrethroid insecticide used extensively in the United States (US) for mosquito control and in agriculture, with approximately 2 million pounds applied each year. Permethrin was selected for investigation based on its widespread use in the US, its inclusion on the Contaminant Candidate List 3 (CCL3), its health hazards, and the lack of previous research on the removal of permethrin from drinking water. The removal of permethrin from water using powdered activated carbon (PAC) was investigated. Equilibrium adsorption experiments to assess removal of cis-, trans-, and total permethrin were conducted using two types of PAC (WPH 650 and WPH 1000). Initial total permethrin concentrations ranged from 2.0 to 4.6 ug/L. PAC doses ranged from 0.0 to 10 mg/L. Results showed that PAC addition is an effective method for removing permethrin from water. Total permethrin concentrations were reduced by 38% with 0.05 mg/L of PAC WPH 650, and reduced to below the detection limit with 3 mg/L of PAC WPH 650. Total permethrin concentrations were reduced by 35% with 0.05 mg/L of PAC WPH 1000 and by 83% with 5 mg/L of PAC WPH 1000. Results for cis- and trans- permethrin were similar. The Freundlich isotherm model provided appropriate fits to the data with an R-squared value of 0.91 for both WPH 650 and WPH 1000."

Termen koliforma bakterier beskriver en grupp indikatororganismer som används för att bedöma renligheten och integriteten hos reningsverk samt distributionssystem som nyttjas vid dricksvattenproduktion. För närvarande ställer styrande förvaltningsmyndigheter endast krav på detektion av antalet koliforma bakterier i dricksvatten via odlingsbaserade metoder. Dessa odlingsbaserade metoder särskiljer och upptäcker koliforma bakterier, och Escherichia coli specifikt, baserat på deras tillväxt samt enzymatiska aktivitet på selektiva kromogena och fluorogena agarplattor. Den definition av koliforma bakterier som dessa lagstiftningar ger upphov till identifierar endast koliforma bakterier baserat på deras metabolism och enzymatiska aktivitet, vilket är otillräckligt för att taxonomiskt identifiera olika bakterier inom denna grupp. För att uppnå detta krävs en definition baserad på fylogenetik. Detta masterexamensarbete beskriver undersökandet av metoder för taxonomisk identifiering av koliforma bakterier baserade på en kombination av odlingsbaserade och molekylära metoder. Vattenprover från Mälaren och Lovös vattenverk i Stockholm användes för att isolera koliforma bakterier via membranfiltrering, följt av odling på selektiva medier. De isolerade kolonierna och membranfiltrerna användes för att extrahera genomiskt DNA, följt av amplifiering av specifika gener associerade med E. coli och koliforma bakterier via PCR. Dessa inkluderade lacZ-genen, uidA-genen, yaiO-genen och 16S rRNA-genen. Produkterna från lyckade genamplifieringar sekvenserades för att taxonomiskt klassificera sekvenserna och identifiera olika koliforma bakterier. Två vattenprover med inloppsvatten skickades även för metagenomisk analys av dess mikrobiom. Dessa resulta indikerade att ett odlingssteg var nödvändigt för att producera tillräckligt med biomassa och genomiskt DNA för att lyckas med genamplifieringar utan att behöva filtrera enorma mängder vattenprover. De utvalda primrarna uppvisade även varierande framgång i att amplifiera målgenerna hos koliforma bakterier. Bakteriekoloniernas fysiska utseende på de selektiva agarplattorna och resultaten från genamplifieringarna uppvisade inte sammanhängande resultat, vilket indikerar ett behov av att ytterligare undersöka och optimera de utförda PCR-protokollen. Trots detta visade metoden potential för taxonomisk identifiering av koliforma bakterier. 16S rRNA-gensekvenserna möjliggjorde identifieringen av potentiella kontaminanter som grampositiva bakterier (Micrococcus and Staphylococcus) och andra, icke-koliforma, gramnegativa bakterier (Pseudomonas and Aeromonas) på de selektiva agarplattorna. Denna information kombinerat med bakteriekoloniernas utseende på agarplattorna och resultaten från övriga genamplifieringar kan möjliggöra ett sätt att skilja på falska positiva, falska negativa, sanna positiva och sanna negativa resultat från nuvarande detektionsmetoder för koliforma bakterier. Ytterligare optimering av olika aspekter av metoderna och arbetsflödet kring identifiering av koliforma bakterier är nödvändig innan man kan införa ett liknande tillvägagångssätt i ett reningsverk.
The term coliform bacteria describes a group of indicator organisms used to measure the cleanliness and integrity of drinking water treatment plants and distribution systems. Currently, the only legal requirement set by government agencies pertains to the detection and enumeration of these bacteria via cultivation-based methods. These methods distinguish coliform bacteria and Escherichia coli based on their growth and enzymatic activity on selective chromogenic and fluorogenic agar plates. However, the legislative definition concerning their metabolism and enzymatic production is insufficient to identify bacteria within this group taxonomically. Instead, a definition based on phylogenetics is required. This master’s thesis describes the exploration of methods for the characterization and identification of coliform bacteria via a combination of cultivation-based and molecular methods. Water samples from Lake Mälaren and the Lovö drinking water treatment plant in Stockholm were used to isolate coliform bacteria via membrane filtration and cultivation on a selective agar medium. The isolated colonies and filtered membranes were subjected to DNA extraction, followed by gene amplification of target genes associated with E. coli and coliform bacteria via PCR. This included the lacZ gene, the uidA gene, the yaiO gene, and the 16S rRNA gene. Successful gene amplicons were sent for sequencing to assign taxonomic values to the sequences and identify coliform bacteria. Two inlet water samples were also sent for metagenomic analysis of the microbiome. An incubation step was necessary to gather enough biomass to extract sufficient genomic DNA for gene amplifications and avoid the need to filtrate large volumes of water. The selected primer pairs exhibited various degrees of success in amplifying the targeted genes of coliform bacteria. The physical appearance of coliform colonies on the selective chromogenic agar plates and the results from the gene amplifications displayed no discernable pattern, indicating the need to further investigate and optimize the PCR procedures. However, the method indicated a potential for coliform bacteria identification. 16S rRNA gene sequences allowed for the distinction of potential contaminants on the selective agar media in gram-positive bacteria (Micrococcus and Staphylococcus) and other non-coliform, gram-negative bacteria (Pseudomonas and Aeromonas). In conjunction with the physical appearance of bacterial colonies on selective media and successful gene amplicons of the targeted genes, this information could allow one to distinguish between false positive, false negative, true positive, and true negative results from current coliform detection and enumeration methods. Further optimization of various aspects of the coliform bacteria identification methods is necessary before introducing a similar approach to a water treatment plant context.

Thesis--University of Western Australia, 2006.
"This thesis is presented in partial fulfilment of the requirements for the Degree of Environmental Engineering, The University of Western Australia, 2006." "Engineering dissertation." Cover title. Includes bibliographical references (p. 92-94). Also available electronically from the Engineers Without Borders website : http://www.ewb.org.au/main/ (Viewed 20/11/2009).

Harmful algal blooms in surface water supply systems pose a threat to public health and are increasing in both frequency and geographical distribution. Cyanobacteria can contribute to taste and odor issues and potentially release harmful cyanotoxins into the water. Several treatment methods are currently employed to control these blooms, including physical separation and chemical pre-oxidation. However, existing oxidation options can be costly; increase the release of intracellular material causing the formation of disinfection byproducts; or disrupt coagulation and filtration processes. This study investigated ferrate (Fe(VI)) as an alternative to other oxidants by measuring its effect on algae cells. Fe(VI) has several advantages as an oxidant, including a high oxidation potential, a low potential for harmful disinfection byproduct production, and formation of Fe(III) - which can potentially be beneficial for downstream treatment processes. Bench scale studies were conducted with laboratory prepared waters containing the common cyanobacteria Microcystis aeruginosa to examine the interactions between Fe(VI) and algae. The effects of ferrate oxidation on algae were characterized by particle counts, UV254 absorbance, total organic carbon (TOC) and dissolved organic carbon (DOC), and total nitrogen. Ferrate decomposition was also monitored. Results showed that Fe(VI) lysed algal cells under some conditions, but further oxidation of released organic matter is possible at some doses. Additionally, some coagulation benefits were observed through an overall decrease in total particle counts and an increase in particle sizes. In general, the results indicate that Fe(VI) could be a possible alternative to other oxidants for water utilities during harmful algal blooms; however, the final fate of resulting organic matter and the potential for disinfection byproduct formation should be further studied.

The primary objective of conventional drinking water treatment and distribution is to deliver to the consumer water that is both aesthetically pleasing and does not constitute a human health risk. To achieve this, water utilities employ a range of physical (i.e. sand and membrane filtration) and chemical (i.e. flocculation and disinfection) barriers in order to reduce the numbers of microorganisms as well as the nutrients that may support their growth within biofilms. In this thesis, biofilms and microbial barriers in water treatment and distribution were therefore examined. The development of biofilms within artificial recharge was investigated in pilot column at Norsborg waterworks in Stockholm. The proportion of active bacteria, measured as numbers of EUB338-positive cells relative to the total number of bacteria enumerated by total direct counts, decreased with time. Through the addition of nutrients however, two to three times more bacteria were able to be active (measured by increase in activity after activation with additional nutrients). By extracting the recalcitrant hydrophilic and hydrophobic fractions of humic substances it was possible to assess the microbiological response to those compounds. It was shown that bacteria more firmly attached to the sand grains preferred the hydrophobic fraction whilst more loosely-associated bacteria preferred the hydrophilic one. The amount of easily degradable matter in raw water (measured as assimilable organic carbon) was generally low. Biofilms were investigated by two different methods for extraction and analysis of microorganisms. Glass slides introduced into the sand material were dominated by α-Proteobacteria, and underestimated loosely-associated bacteria whilst extracts from sand were dominated by γ-Proteobacteria, and also caused variations due to the extraction method employed

The barrier function of biofilms was investigated in biofilters, also fed with raw water from Gothenburg. The focus here was on particle removal in size-intervals of 1-15 µm (protozoa) and 0.4 - 1 µm (bacteria). In both size fractions, autofluorescent microalgae, which were naturally-occurring in raw water, were also enumerated in parallel. Their removal was 60-90%. In parallel, defined amounts of fluorescent hydrophilic and hydrophobic microspheres (1 µm) were added. They showed a reduction of hydrophobic spheres by 98% and hydrophilic ones by 86%. Removal of viruses was determined by adding a defined dose of bacteriophages and gave lower reduction values of 40 - 61%. Both naturally-occurring particles in defined size intervals and added particles or organisms were shown to provide a clearer picture of barrier function than usually performed measurements of turbidity.

The efficiency of chemical treatment against viruses was also measured in a pilot-plant in Gothenburg. It was shown that commonly-used MS-2 bacteriophages were much more sensitive than φX174 bacteriophages. Reduction of MS-2 over the entire chemical step (when added after dosing of chemicals) was 5-log10 whilst φX174 was reduced by 1-log10. The latter was shown to be a more conservative model for virus removal. The effects of different steps in the chemical precipitation showed that the primary dosage of chemicals and the development of flocs had great importance for the assessment of removal efficacy. When added before the dosing of chemicals, reduction of φX174 and MS-2 was 3.8-log10 and 6.2-log10, respectively.

The establishment of biofilm within a distribution system was followed in a 1000 metre long pilot-plant (with parallel lines) at Lovö waterworks as well as in two of Stockholm's main distribution systems (Nockeby and Hässelby). The pilot-plant was shown to satisfactorily represent processes within the distribution systems. The development of biofilms was slow, producing thin biofilms over a one to two month periods. Numbers of bacteria were generally in the range of 104 - 105 per cm2, which is lower than shown in other earlier investigations. The implementation of primary ultra viloet (UV)-treatment in place of chlorination (both being chloraminated prior to distribution) did not considerably change the numbers of bacteria in biofilms. No significant difference could be seen between the system that had UV-treatment as a primary treatment step, and the system that was chlorinated over the whole period. Chlorine residuals were generally low at the distal parts of the distribution systems. Naturally-occurring protozoa were present in distribution systems in numbers ranging from 280 - 3500 protozoa per cm-2. Protozoa may play a significant role as predators of biofilm bacteria, however they can also act as protection for bacteria against external influences i.e. disinfection. Should sudden contamination of a distribution system occur, biofilm can provide protection and act as a site for potential regrowth of introduced microorganisms. Biofilms developed in the pilot-scale that represented water from different distances from waterworks were exposed to fluorescent microspheres, (hydrophobic and hydrophilic, 1 µm) legionellae (as a model for opportunistic bacterial pathogens) and bacteriophages (human enteric virus model) in order to determine their accumulation and persistence within the biofilm, and release to the bulk water. It was shown that introduced model organisms were released continuously, primarily through desorption, and additionally through the influence of disinfection and activity of protozoa.

Desorption was also assessed in a laboratory experiment under laminar and turbulent flow. Laminar flow conditions that were representative of a distribution system gave a slow and continual release of individual cells, whilst turbulent conditions detached larger aggregates. In conclusion, based on this work an increased understanding was gained both of barrier functions at the different steps of water treatment, their effects on overall biofilm dynamics and structure and the role that biofilm plays within the drinking water system itself.

The aim of this study was to evaluate the effectiveness of water treatment processes of two drinking water plants to remove immunotoxins and steroid hormones. Raw and treated drinking water was screened for effects on inflammatory activity using the biomarker IL-6, humoral immunity using the biomarker IL-10 and cell mediated immunity using the biomarker IFN-&gamma
. In vitro human whole blood culture assays were used in order to elucidate potential immunotoxicity.