ABSTRACT As far back as the early 1900?s when it was discovered that water could be a mode of transmitting diseases, chlorine was used to disinfect water. In the 1970?s, the formation of disinfection by-products (DBPs) from the reaction of chlorine with natural organic matter was discovered. Since then there have been various studies on alternative disinfectants that could inactivate microorganisms and at the same time form less or no disinfection by-products. More recently the ultraviolet (UV) irradiation has been used to both disinfect and remove organic contaminants in drinking water. Though the use of UV irradiation has been found to be very effective in the inactivation of microorganisms, it does not provide a residual effect to maintain the water?s microbial quality in the distribution system. Due to this, a secondary disinfectant such as chlorine has to be used to achieve microbial stability, suggesting that the formation of chlorination disinfection by-products would still occur but perhaps in different quantities and with different chemical species. In this research, the use of factorial experiments and single factor experiments were used to determine the effects of pH, alkalinity and UV-fluence (dose) on the formation of three classes of disinfection by-products; haloacetic acids (HAAs), haloacetonitriles (HANs) and trihalomethanes (THMs). These disinfection by-products were measured in water samples following post-UV chlorination and the UV treatment was either UV photolysis or UV/H₂O₂. From the factorial experiment results, treatment of synthetic water with UV/H₂O₂, an advanced oxidation process (AOP), produced fewer post-UV chlorination disinfection by-products (PCDBPs) than UV photolysis. For chlorinated PCDBPs, the percentage difference between UV photolysis and UV/H₂O₂ was 55, 65 and 38% for total HAAs (HAA₉), total HANs (THANs) and total THMs (TTHMs) respectively. The percentage difference between UV photolysis and UV/H₂O₂ for brominated PCDBPs was 41 and 42% for HAA9 and TTHMs respectively. Both the use of pH and alkalinity proved to be factors that were significant in affecting the yields of the PCDBPs studied. Increases in alkalinity were found to increase the formation of PCDBPs in the treatment of synthetic water with UV/H₂O₂. Alkalinity had the opposite effect for PCDBP formed under UV photolysis conditions. Increases in pH always decreased the formation of PCDBPs. In the single factor experiments, haloacetic acid concentrations were unaffected as alkalinity was increased but dichloroacetonitrile and chloroform increased in concentration under treatment conditions of UV photolysis followed by chlorination. The UV/H₂O₂ treatment resulted in a decrease in concentration of the PCDBPs. In the pH studies, water samples were subjected only to the UV/H₂O₂ treatments and a reduction in concentration of PCDBPs occurred between pH 7 and 9.

The use of sunlight for water disinfection has been practiced since ancient times. Only in the last three decades has solar disinfection become widely recognized as a viable means of providing safe drinking water to the disadvantaged portion of the world’s population. The World Health Organization estimates that 1.6 million people die every year because of waterborne diseases. <br/><br/> The Swiss Federal Institute of Environmental Science and Technology and their Department of Water and Sanitation in Developing Countries have been instrumental in propagating the solar water disinfection (SODIS) process in developing countries. The reason for this technology being widely used and accepted is its ease of use and effectiveness: water is placed in clear plastic bottles and exposed to direct sunlight for approximately six hours. The microorganisms in the water absorb the sunlight and it, in turn at sufficient UV dosages, causes mutations to their genetic material, inhibiting reproduction. Although some pathogens may still be viable they are no longer infective. The result is microbiologically safe water. <br/><br/> Research to date has explored everything from which colour and size the SODIS containers should be to whether adding catalysts to the water before exposure improves disinfection. Apart from a few studies that examined the effect of shaking the bottles (to entrain air) before exposure, there has been limited research on pretreatments for enhancing solar disinfection. <br/><br/> The focus of this project was to explore two pretreatments for SODIS and determine how they affect the efficiency of the process. The first stage was to examine one of the currently used pretreatments: cleaning the water containers before use. The second stage was to develop an accessible, low-cost filtration technique to remove particles from the water before exposure to sunlight. Particles in the water disperse the light and protect the microorganisms from being inactivated, so it is important to have as few particles as possible; the recommended upper limit is 30 NTU for solar disinfection. In many instances, surface water with high turbidity (greater than 200 NTU) serves as the only source for drinking water in developing areas. <br/><br/> The first series of experiments in the current research evaluated if cleaning the bottles was necessary and if so, which cleaning agents would be most effective and available. The agents selected were 70% isopropyl alcohol, a soap-water mixture, and lime juice. The experiments demonstrated that cleaning with 70% isopropyl alcohol did not affect the process in any way. Cleaning with the soap-water mixture did have a slightly negative effect on the process; there was substantial microbial recovery when bottles were kept in the dark overnight. In the case of the lime juice, it actually inhibited the disinfection process. It is necessary to remove any debris that might exist within the containers before using them, but using a chemical cleaning agent or mechanically scrubbing can decrease the amount of disinfection that occurs during SODIS. Thus, it is suggested that using a chemical pretreatment is not necessary and has the potential to inhibit disinfection, especially without proper training or technical knowledge. <br/><br/> The second series of experiments identified the optimal design for a low-cost roughing filter that could be used to remove particles from water before exposure to sunlight. The roughing filter that was built from the same plastic pop bottles used for solar disinfection, as well as gravel and sand. It was constructed with three centimetres of gravel on the bottom of the pop bottle and then 17 cm of coarse sand was added on top to make the total filter height 20 cm. A 0.6 mm hole was made at approximately 1.5 cm from the bottom of the bottle using a standard sewing needle. Each filter run consisted of 10 L of water at approximately 200 NTU. Experimental results indicated that 95% removal of turbidity could be achieved. These roughing filters can be constructed from readily available and affordable materials in developing countries and produce an effluent water quality of less than 30 NTU when initial turbidities are greater than 200 NTU. <br/><br/> Finally, the third series of experiments focused on testing the newly developed roughing filter in series with SODIS to evaluate the system as a whole. The results confirmed that using the roughing filter, as a pretreatment to SODIS, is a highly effective means of improving the disinfection potential of the process. These roughing filters produce an effluent water quality of less than 30 NTU, which is required for SODIS, making them a viable pretreatment for turbid water intended for SODIS use.

ABSTRACT As far back as the early 1900?s when it was discovered that water could be a mode of transmitting diseases, chlorine was used to disinfect water. In the 1970?s, the formation of disinfection by-products (DBPs) from the reaction of chlorine with natural organic matter was discovered. Since then there have been various studies on alternative disinfectants that could inactivate microorganisms and at the same time form less or no disinfection by-products. More recently the ultraviolet (UV) irradiation has been used to both disinfect and remove organic contaminants in drinking water. Though the use of UV irradiation has been found to be very effective in the inactivation of microorganisms, it does not provide a residual effect to maintain the water?s microbial quality in the distribution system. Due to this, a secondary disinfectant such as chlorine has to be used to achieve microbial stability, suggesting that the formation of chlorination disinfection by-products would still occur but perhaps in different quantities and with different chemical species. In this research, the use of factorial experiments and single factor experiments were used to determine the effects of pH, alkalinity and UV-fluence (dose) on the formation of three classes of disinfection by-products; haloacetic acids (HAAs), haloacetonitriles (HANs) and trihalomethanes (THMs). These disinfection by-products were measured in water samples following post-UV chlorination and the UV treatment was either UV photolysis or UV/H₂O₂. From the factorial experiment results, treatment of synthetic water with UV/H₂O₂, an advanced oxidation process (AOP), produced fewer post-UV chlorination disinfection by-products (PCDBPs) than UV photolysis. For chlorinated PCDBPs, the percentage difference between UV photolysis and UV/H₂O₂ was 55, 65 and 38% for total HAAs (HAA₉), total HANs (THANs) and total THMs (TTHMs) respectively. The percentage difference between UV photolysis and UV/H₂O₂ for brominated PCDBPs was 41 and 42% for HAA9 and TTHMs respectively. Both the use of pH and alkalinity proved to be factors that were significant in affecting the yields of the PCDBPs studied. Increases in alkalinity were found to increase the formation of PCDBPs in the treatment of synthetic water with UV/H₂O₂. Alkalinity had the opposite effect for PCDBP formed under UV photolysis conditions. Increases in pH always decreased the formation of PCDBPs. In the single factor experiments, haloacetic acid concentrations were unaffected as alkalinity was increased but dichloroacetonitrile and chloroform increased in concentration under treatment conditions of UV photolysis followed by chlorination. The UV/H₂O₂ treatment resulted in a decrease in concentration of the PCDBPs. In the pH studies, water samples were subjected only to the UV/H₂O₂ treatments and a reduction in concentration of PCDBPs occurred between pH 7 and 9.

The use of sunlight for water disinfection has been practiced since ancient times. Only in the last three decades has solar disinfection become widely recognized as a viable means of providing safe drinking water to the disadvantaged portion of the world’s population. The World Health Organization estimates that 1.6 million people die every year because of waterborne diseases. <br/><br/> The Swiss Federal Institute of Environmental Science and Technology and their Department of Water and Sanitation in Developing Countries have been instrumental in propagating the solar water disinfection (SODIS) process in developing countries. The reason for this technology being widely used and accepted is its ease of use and effectiveness: water is placed in clear plastic bottles and exposed to direct sunlight for approximately six hours. The microorganisms in the water absorb the sunlight and it, in turn at sufficient UV dosages, causes mutations to their genetic material, inhibiting reproduction. Although some pathogens may still be viable they are no longer infective. The result is microbiologically safe water. <br/><br/> Research to date has explored everything from which colour and size the SODIS containers should be to whether adding catalysts to the water before exposure improves disinfection. Apart from a few studies that examined the effect of shaking the bottles (to entrain air) before exposure, there has been limited research on pretreatments for enhancing solar disinfection. <br/><br/> The focus of this project was to explore two pretreatments for SODIS and determine how they affect the efficiency of the process. The first stage was to examine one of the currently used pretreatments: cleaning the water containers before use. The second stage was to develop an accessible, low-cost filtration technique to remove particles from the water before exposure to sunlight. Particles in the water disperse the light and protect the microorganisms from being inactivated, so it is important to have as few particles as possible; the recommended upper limit is 30 NTU for solar disinfection. In many instances, surface water with high turbidity (greater than 200 NTU) serves as the only source for drinking water in developing areas. <br/><br/> The first series of experiments in the current research evaluated if cleaning the bottles was necessary and if so, which cleaning agents would be most effective and available. The agents selected were 70% isopropyl alcohol, a soap-water mixture, and lime juice. The experiments demonstrated that cleaning with 70% isopropyl alcohol did not affect the process in any way. Cleaning with the soap-water mixture did have a slightly negative effect on the process; there was substantial microbial recovery when bottles were kept in the dark overnight. In the case of the lime juice, it actually inhibited the disinfection process. It is necessary to remove any debris that might exist within the containers before using them, but using a chemical cleaning agent or mechanically scrubbing can decrease the amount of disinfection that occurs during SODIS. Thus, it is suggested that using a chemical pretreatment is not necessary and has the potential to inhibit disinfection, especially without proper training or technical knowledge. <br/><br/> The second series of experiments identified the optimal design for a low-cost roughing filter that could be used to remove particles from water before exposure to sunlight. The roughing filter that was built from the same plastic pop bottles used for solar disinfection, as well as gravel and sand. It was constructed with three centimetres of gravel on the bottom of the pop bottle and then 17 cm of coarse sand was added on top to make the total filter height 20 cm. A 0.6 mm hole was made at approximately 1.5 cm from the bottom of the bottle using a standard sewing needle. Each filter run consisted of 10 L of water at approximately 200 NTU. Experimental results indicated that 95% removal of turbidity could be achieved. These roughing filters can be constructed from readily available and affordable materials in developing countries and produce an effluent water quality of less than 30 NTU when initial turbidities are greater than 200 NTU. <br/><br/> Finally, the third series of experiments focused on testing the newly developed roughing filter in series with SODIS to evaluate the system as a whole. The results confirmed that using the roughing filter, as a pretreatment to SODIS, is a highly effective means of improving the disinfection potential of the process. These roughing filters produce an effluent water quality of less than 30 NTU, which is required for SODIS, making them a viable pretreatment for turbid water intended for SODIS use.

In the first phase of this project three enhanced large diameter (> 60 cm) residential wells were constructed at a study site in Lindsay, Ontario. Two wells were constructed using concrete tile casing while the other well was constructed using galvanized steel casing. Javor (2010) evaluated various aspects of drinking water well construction and design to determine the susceptibility of residential large diameter drinking water wells to surface water and airborne contamination. One of the purposes of these new installations was to remove the uncertainty with respect to construction methods, age and maintenance that is characteristic of residential drinking water well performance studies. Javor (2010) conducted a field and laboratory study to assess the performance of several design changes that were thought to improve the integrity of large diameter drinking water wells. These experiments were also used to determine whether one design was more prone to atmospheric and/or surface water contamination than another. During the second phase of this project routine monitoring was continued and data pertinent to assess the performance of the test wells were collected using the same instrumentation. This routine monitoring involved the visual inspection of the wells, collection of well water elevation, collection of soil temperature profile data, collection and analysis of water samples, and collection of cumulative water volumes extracted from the test wells. In addition to the routine monitoring, a ground penetrating radar (GPR) survey was performed in October 2010 to complement the previous data collected during February 2010. Smoke tracer tests were performed under non-frozen and frozen conditions to re-assess the potential pathways of contaminants between the atmosphere and the interior of the test wells. Bacteriological indicators and high concentrations of two dissolved ions were detected in all test and monitoring wells. The smoke tracer tests demonstrated that pathways for airborne contaminants to enter the test wells exist with similar pathways observed in the winter and the summer. GPR surveys indicated that the bentonite slurry annular sealant was the most homogeneous media. A baseline characterization of the microbial nature of the biofilm performed in three of the test wells (CTH1, ETH1 and ETH3) indicated that the sessile bacteria are more metabolically diverse than suspended bacteria, and that this diversity is even higher in the concrete cased wells. Biofilm characterization performed on concrete, fibreglass and galvanized steel coupons incubated in two of the test wells (concrete and galvanized steel) showed that bacteria in the concrete cased wells barely colonized on fiberglass and galvanized steel, while bacteria in the galvanized steel cased well did not have difficulty colonizing on any of the casing materials. The results of the biofilm cleaning study indicated that the use of pressure washing combined with chlorination effectively removed biofilm grown on galvanized steel and fibreglass casing materials. This study investigated various factors that could affect the performance of large diameter drinking water wells. Since the test wells used in this study were under the direct influence of surface water a comparison between the various annular sealants was problematic. However, the three enhanced test wells outperformed the conventional test well. The observations from the smoke tracer tests performed under non-frozen and frozen conditions indicate that the Poly-Lok lid seam is the most prevalent pathway for airborne contaminants to enter a well. Fibreglass may be the preferred choice for large diameter well casing material since fibreglass is corrosion resistant, lightweight, easy to install, has a high strength to weight ratio, and a greater degree of biofilm was able to be removed from fibreglass casing material than from galvanized steel casing material.

<p>In order to meet disinfection guidelines, wastewater utilities must achieve a high level of treatment before discharging treated water for irrigation or industrial use. However, public pressure to reduce disinfection by-products and pharmaceutically-active compounds, recently-promulgated regulations on chlorine-resistant microorganisms such as Cryptosporidium parvum, and growth in population and water demand have driven an interest in alternatives to chlorination. The WateReuse Foundation has funded WRF 02-009 (Innovative Treatment Technologies for Reclaimed Water), which is a survey of current and emerging reuse water treatment technologies. The goal of the project is to evaluate treatment technologies can provide adequate recycled water effluent without the cost of reverse osmosis (RO) or the disinfection by-products (DBPs) formed during chlorination.</p><p>The inactivation of indigenous microorganisms (total and fecal coliform bacteria, and total aerobic spores) and spiked surrogate, respiratory, and enteric viruses (MS-2 bacteriophage, adenovirus type 4, reovirus type 3, and coxsackievirus type B5) and chemical degradation by wastewater treatment technologies was evaluated on the bench-scale. These include: low- and medium-pressure UV, LPUV/H₂O₂, ozonation, O₃/H₂O₂, peracetic acid (PAA), LPUV/PAA, chlorination, chloramination, and ultrafiltration. The applicability of the candidate disinfection methods, especially emerging and comparatively untested methods such as PAA and advanced oxidation processes (AOPs), was studied through comparison of their performance and the important water matrix parameters (e.g., alkalinity, BOD, TSS, etc.).</p><p>Of the chemical disinfectants, molecular ozone and free chlorine were the most effective, with substantial coliform and virus kill at low doses. Combined chlorine in the form of monochloramine had a reduced disinfectant capacity than free chlorine, and peracetic acid (PAA) performed equally as well as free chlorine with respect to coliform bacteria in some instances but had little to no impact on spiked MS2 bacteriophage. None of the aforementioned disinfectants had an appreciable impact on indigenous aerobic spore-forming bacteria due to their physiology. UV and O₃ rapidly killed human enteric and respiratory viruses, but a consistent benefit by AOPs over their base technologies was not observed for any of their base technologies.</p><p>Low and medium-pressure UV inactivated free-floating indigenous coliform bacteria almost immediately, while slower inactivation rates at higher UV fluences illustrated the "tailing" behavior observed when bacteria are embedded in or shielded by particulate matter. Log-linear inactivation of spiked viruses and indigenous aerobic spores by UV was consistent across the utility waters. The UV-based advanced oxidation processes (UV/H₂O₂ and UV/PAA) destroyed spiked organic compounds at much higher rates than direct UV photolysis, while O₃, with or without H₂O₂ , oxidized spiked compounds and reduced estrogenicity (EEQ) at low doses. Recalcitrant chlorinated hydrocarbons such as TCEP were only moderately removed by the tested AOPs, but low doses of O₃ (3 ppm residual O₃) reduced estrogenic activity by 99%. Like other disinfection processes, AOP performance is dependant on pretreatment, especially concerning particulates.</p> / Dissertation

Disinfectants, such as chlorine, are widely used in water treatment plants to ensure the safety and quality of drinking water. However, these disinfectants easily react with some natural or man-made organic compounds in raw water and form disinfection by-products (DBPs). For example, halogenated acetic acid (HAAs) and trihalomethanes (THMs) are two main components of DBPs. These DBPs contained in drinking water will increase the risk of cancer in human body. Therefore, researches on halogenated acetic acid¡¦s potential of causing cancer have increased currently. Organic acids are usually the reactants which proceed in chlorination reaction into products of disinfection by-products in water treatment plant. The purpose of this study is to investigate adsorption characteristics in solution by using tests of kinetics and equilibrium adsorptions and kinetic model evaluations of selected fulvic acids (FA) extracted from raw water. Therefore, we use commercial single-walled carbon nanotube (SWCNT) for the adsorbents, and calculate thermodynamic parameters (£GG, £GS and £GH) in order to further understand the adsorption mechanism of CNTs. The maximum adsorbed amounts of FA onto SWCNTs was calculated by the Langmuir model at 25¢J, reaching 61.88mg / g which were much higher than that onto commercially available granular activated carbon (10.69 mg/g). The adsorption capacity of FA onto CNTs increased with decreasing outer diameter of CNTs (dp), molecular weight of FA, trmperature and pH value in all texts. In the condition of constant temperature 25¢J, we analyzed HAAFP after the test of equilibrium adsorption and that the removal efficiency of HAAFP could reach 40.76%. The best selection in kinetic models evaluation, fitting models such as Modified Freundlich equation, Pseudo-1st-order equation and Pesudo-2nd-oder equation, is Modified Freundlch equation model. In addition, intraparticle diffusion equation model was fitted well and showed adsorption process was controlled by pore diffusion. We calculated the activation energy of carbon nanotube adsorption of FA and found that film diffusion was the main factor for controlling reaction rate. According to results of thermodynamic parameters indicated that the adsorption was spontaneously and an exothermic reaction. It is obvious that the adsorption capacity as well as the reaction rate of CNTs are superior to that of granular activated carbon in raw water. These results suggest that CNTs possess highly potential applications in environmental protection. In the future, if we can combine nanotube technology with disinfection technology and apply such technique on the end of processing unit for design of either the domestic treatment facilities or small simple water treatment in drinking water. Thus it will enhance the new treatment technology of drinking water and the safety of the public health. Another possibility will be to promote the opportunity of marketing development in drinking water.

Taiwan Water Supply Cooperation (TWSC) has upgraded traditional purification processes into advanced treatment systems in south Taiwan for many years. The removal efficiency of assimilable organic carbon (AOC) by ultrafiltration (UF) with reverse osmosis (RO) systems was 47% was lower than that of 62% by ozone with biological activated carbon system (BAC). In this work, we investigate the removal of AOC and disinfection by products formation potential (DBPFP) of raw water took from a water treatment plant by using BAC and membrane treatment units. BAC system of granular activated carbon(GAC) and powder activated carbon (PAC) showed two kind carbons have certain efficiency for AOC removal. Results we found could reach above 50% (from 44.28¡Ó9.84£gg acetate-C/L reduce to 20.93¡Ó4.25£gg acetate-C/L for GAC and from 45.92¡Ó17.75£gg acetate-C/L reduce to 21.23¡Ó4.25£gg acetate-C/L for PAC), when hydraulic retention time (HRT) in BAC reactor was at 1 hour. When HRT raised to 6 hours the concentration of AOC in effluent of BAC systems were reduced under 15 £gg/L, and removal efficiency could reach above 70%. The suggested limit level of AOC is 50 £gg/L of drinking water. In removal of DBPFP, BAC of two carbons has showed certain efficiency on trihalomethanes formation potential (THMFP) and haloacetic acids formation potential (HAA5FP). The results were done in removal of THMFP (from 20.54¡Ó6.48£gg/L reduce to 14.21¡Ó4.47£gg/L for GAC and from 24.64¡Ó6.74£gg/L reduce to 14.75¡Ó4.04£gg/L for PAC) and HAA5FP (from 39.64¡Ó10.38£gg/L reduce to 17.35£gg/L for GAC and from 17.86¡Ó5.13£gg/L reduce to 11.76¡Ó3.76£gg/L for PAC) in BAC reactors. They were all lower than national standard of drinking water (THMs 80£gg/L, HAAs 60£gg/L). It is believed that two kind carbons in BAC system could all reduce effectively on AOC and DBPFP to obtain high quality of drinking water with biological stability at HRT of 6 hours.

Chlorine is always used in disinfection process of water treatment plant (WTP) in Kaohsiung, and the major of disinfection by-products (DBPs) is THMs. Reaction of THMs producing were found in relation to lots of factors of water quality. Therefore we used SPSS to analysis the relation between water quality and THMs content for making prediction model of THMs formation in water distribution system in downtown Kaohsiung city. It is expected to estimate the concentration of THMs with a simple method, and to reduce THMs by controlling some items of water quality. While the variance of TOC value is low, we found that concentration of THMs is related to temperature, pH, and residual chlorine by regression method. In these items, residual chlorine had the highest correlation. While the variance of TOC value is high, the correlation between the three items and THMs is weaker than the front one. From this finding, TOC is best one fitting factor in prediction of THMs. In this study, we found that R-square value of Multivariate regression prediction is higher than the value of Univariate regression prediction probably for THMs producing is a complex reaction, so formation model was hard using only one item of water quality.

The main objective of this study was to conduct a systematic investigation of the disinfection by-products (DBPs) formation in low-bromide and low- specific ultraviolet absorbance (SUVA) waters and the control of DBP precursors by nanofiltration (NF) and ultrafiltration (UF) processes in such waters. To this end, firstly, the effect of bromide ion on the formation and speciation of DBPs was investigated. In fractionated Alibeyk&ouml / y source water, increasing bromide concentrations in NOM fractions increased concentrations of trihalomethanes (THMs), haloacetic acids (HAAs) and adsorbable organic halides (AOX) and resulted in a shift toward the formation of brominated species. Secondly, the impacts of SUVA and differential UV spectroscopy (&amp / #916 / UV), which has been shown to correlate well with DBP formation has been elucidated in terms of DBP formation and speciation. Alibeyk&ouml / y and Karaca&ouml / ren waters were fractionated employing various separation methods and it has been shown that SUVA did not correlate well with the formation and speciation of THMs and HAAs in tested low-SUVA waters. Similarly, no correlations were found among THMs/HAAs formations and &amp / #916 / UV. Finally, the NOM rejection performances of NF and UF membranes were investigated. NF and UF membranes (&lt / 2000 dalton) was found to be suitable for the removal NOM from surface waters having low SUVA and low bromide contents. While higher molecular weight (HMW) fraction was successfully rejected (&gt / 90%) by all membrane types, lower molecular weight (LMW) fraction could be removed with ranging efficiencies from 1.5 to 30%. NF membranes provided DOC, UV254 absorbance, THM, and HAA reductions up to 90%.