There is much debate on the carcinogenic potential of disinfection by-products (DBP) in chlorinated water supplies. Until recently, epidemiological studies have been limited in their ability to examine accurately the risk of cancer with exposure to environmental carcinogens. This has largely been due to the long latency periods associated with cancer development, and the difficulties in accurately estimating chronic exposure. Although there is evidence, from predominantly case-control studies, of increased bladder cancer with exposure to chlorinated water supplies, the evidence is inconclusive. ¶ In an attempt to determine the carcinogenic potential of trihalomethanes (THMs) in chlorinated water, this study utilises DNA damage to bladder cells, evident as micronuclei, as a pre-clinical outcome measure. Using a pre-clinical marker helps overcome some of the limitations associated with long latency periods. The study improves on previous studies by estimating exposure to DBP at an individual level, and takes into consideration ingestion, inhalation and dermal exposure. ¶ A cohort study was undertaken in three Australian communities. The Bungendore (NSW) water supply was not chlorinated thereby providing a community unexposed to DBPs from chlorinated water. Canberra (ACT) and Adelaide (SA) had intermediate and relatively higher (but still within NHMRC guideline levels) of DBPs in the reticulation system. Trihalomethane levels in reticulated water (external dose) and in urine (internal dose) were used as exposure indices. As well, intake dose was computed by adjusting external dose for individual variations in ingestion and bathing. The primary outcome measure was the prevalence of micronuclei in bladder epithelial cells. A DNA index derived from flow cytometry was also used to estimate DNA damage in bladder cells. Associations between exposure and outcome were estimated using Poisson regression models, having identified and adjusted for interaction effects and confounders. ¶ A total of 529 participants were eligible to participate, of which 348 (65.8%) completed all aspects of the study. Analysis was limited to the 228 participants (65.53% of those who completed the study) who had slides suitable for micronuclei scoring. One hundred and forty three (63%) of the 228 participants were from the exposed communities, while 85 (37%) were from the unexposed community. This sample exceeded the estimated 50 per group required to detect a relative risk of 1.4, with a significance level of 0.05 and 80% power. ¶ External dose for total THM for the two chlorinated (exposed) communities ranged from 37.75 to 157.25 mg/l. Intake dose estimated by fluid intake diary ranged from 2.9 to 469.5 mg/l, while a retrospective questionnaire estimated intake dose to range from 0 to 409.4 mg/l. Internal dose (urine levels) of total THM for the same two communities ranged from 0 to 6.82 mg/l. Adjusted risk estimate for DNA damage to bladder cells (using the micronuclei assay) when total THM was assessed by available dose was 1.0002 (0.997 to 1.003), by intake dose estimated by fluid intake diary was 1.0001 (0.998 to 1.002), by intake dose estimated by questionnaire was 1.001 (0.999 to 1.003), and by internal dose was 1.05 (0.89 to 1.24). Using DNA index from flow cytometry as the outcome measure also did not identify significant associations, except when exposure was assessed as available dose of total THM (RR=1.0042; 1.0003 to 1.0081). ¶ The results suggest that THM levels are not significantly associated with DNA damage to bladder cell. This supports suggestions of THMs being non-genotoxic. Further work is required to assess the relationship between THM and the more mutagenic compounds, and to assess the carcinogenicity of the more mutagenic compounds at concentrations occurring in drinking water.

The antibacterial agent, triclosan, is widely used in many household personal care products, and it has recently been detected in wastewater treatment plant effluents and in source waters used for drinking water supply. Accordingly, the reactivity of triclosan with the disinfectants used in wastewater treatment and in the production of potable water is of interest. Monochloramine is used as an alternative disinfectant in drinking water treatment to minimize production of regulated disinfection by-products. This study examined the reactions between triclosan and monochloramine and involved analysis of monochloramine and triclosan decay and product formation under drinking water treatment conditions over a pH range of 6.5 to 10.5. Monochloramine decay in the presence of triclosan was measured relative to monochloramine auto-decomposition in the absence of triclosan using UV-VIS spectrophotometry. Experimental results showed that the monochloramine auto-decomposition intermediates, free chlorine and dichloramine, are responsible for a majority of the observed triclosan decay and product formation. A kinetic model for monochloramine auto-decomposition was modified to include terms and rate coefficients for the reactions of triclosan with monochloramine (<i>k</i> = 90.4 M^-1h^-1), free chlorine (<i>k</i> = 1.94&#215;10⁷ M^-1h^-1), and dichloramine (<i>k</i> = 2&#215;10⁵ M^-1h^-1), and was able to predict triclosan and monochloramine decay. It was determined that the reactions of dichloramine and free chlorine with triclosan were 10³ and 10⁵ times faster, respectively, than the reaction of monochloramine with triclosan. The products of these reactions, detected using GC-MS, included three chlorinated triclosan intermediates, 2,4-dichlorophenol, and 2,4,6-trichlorophenol. Low levels of chloroform were detected at pH values of 6.5 and 7.5. / Master of Science

Triclosan, 5-chloro-2-(2,4 dichlorophenoxy)phenol, is an anti-microbial additive in a plethora of Pharmaceutical and Personal Care Products (PPCPs) including, toothpastes, hand creams and soaps, and acne creams. Because many triclosan containing products are topical solutions that are readily washed down the drain, significant quantities of triclosan can be introduced to wastewater treatment systems and eventually, to surface waters. Consequently, triclosan has become a contaminant of concern. The reactions between triclosan and free chlorine have been examined previously; however, no kinetic data for these reactions have been reported for conditions typical of drinking water treatment. This investigation focused specifically on the kinetics of the triclosan and free available chlorine (FAC) reactions under drinking water treatment conditions. Triclosan readily reacted with free chlorine via a second-order reaction (first order with respect to each species). No significant temperature dependency was observed from 8 to 25 °C. The reaction stoichiometry was determined to be 1:1 (triclosan oxidized per free chlorine reduced and did not vary over the pH range examined (pH 4-12). However, the reaction rate coefficients exhibited a significant pH dependency. A model that incorporates the rate coefficients for the reactions between HOCl and both neutral and anionic forms of triclosan was generated to fit the experimental data. The anionic free chlorine species hypochlorite (OCl-) was determined to play an insignificant role in the overall rate of reaction, and therefore, only the reactions involving HOCl were incorporated into the model. Additionally, a hypothesized reaction mechanism was tentatively shown to fit the collected data and its strong pH dependency. / Master of Science

Disinfectants such as chlorine are used in drinking water treatment to protect the public health from pathogenic microorganisms. However, disinfectants also react with humic material present in raw water sources and produce by-products, such as trihalomethanes. Total trihalomethanes (TTHMs) include four compounds: chloroform, bromodichloromethane, dibromochloromethane and bromoform. TTHMs are carcinogenic and have been found to cause adverse pregnancy outcomes. Therefore, the United States Environmental Protection Agency (U.S. EPA) has set the maximum contaminant limit for TTHMs at 80 ìg/L. Additional regulations require reliable drinking water disinfection for resistant pathogens and treatment plants must simultaneously control TTHMs and achieve proper disinfection. Research has shown that THM formation depends on several factors. THM concentrations increase with increasing residence time, increased temperature and increased pH. The disinfectant type and concentration is also significant: THM concentrations can be minimized by using lower disinfectant doses or alternative disinfectants to chlorine such as chloramines. Chloramines are formed by the addition of both chlorine and ammonia. The Worcester Water Filtration Plant in Holden, MA currently uses both ozone and chlorine for primary disinfection. Chlorine is also used for secondary disinfection. This study analyzed the effect of using chloramines versus free chlorine on TTHM production at the plant. Water samples were collected from the plant, dosed with chlorine/chloramines and stored for their designated residence times. The residual chlorine was then quenched with sodium thiosulfate and the samples were analyzed for TTHM concentration using a GC-MS. Experiments were conducted in December of 2001, April of 2002 and February of 2003, and examined varying residence times, pH conditions, temperatures, chlorine to nitrogen ratios and free chlorine reaction periods. The study found that as the pH increased the TTHMs increased. For the free chlorine samples, as residence time increased, the TTHMs increased. For the chloramination samples it was found that most of the TTHMs were formed in the first six hour reaction period with free chlorine before ammonia was added. Therefore, reducing this free chlorine contact period to 0 or 3 hours would reduce THM formation further. Chlorine to nitrogen ratios between 3:1 and 7:1 were all effective at reducing THM concentrations. Using chloramination at a 3:1 ratio (with a 6 hour free chlorine time) reduced THM formation by approximately 38% for a 54 hour residence time compared to using free chlorine.

The National Aeronautics and Space Administration (NASA) is considering the use of iodine for disinfection of recycled wastewater and potable water in the International Space Station (ISS). Like Chlorine and other halogen compounds, iodine can form disinfection by-products (DBPs) in the presence of organic compounds. Recycled wastewater sources proposed for reuse in the space station include laundry, urine, and humidity condensate. These contain large concentrations of iodine-demanding compounds, including phenol (Barkely et al., 1992). Therefore, the potential for the formation of iodine disinfection by-products (IDBPs) is of concern. Based on the characteristics of the ISS recycled wastewater sources and potable water treatment system, a series of experiments was designed to evaluate the formation of IDBPs under different experimental conditions. Studies were conducted by reacting various concentrations of iodine with phenol at pH 5.5 and 8.0.Iodine concentrations of 10 and 50 mg/L and phenol concentrations of 5 and 50 mg/L were used. Reactions were monitored for up to 32 days for the formation of IDBPs. All reactions were maintained at 20 C in dark. High Performance Liquid Chromatography (HPLC) and Gas Chromatography/Mass Spectrometry (GC/MS) were used for identification and quantitative analysis of phenolic compounds. Spectrophotometry was used to monitor the iodine concentrations. Falvor Profile analysis (FPA) method was used to evaluate the odor characteristics of the phenolic compounds. Reactions of iodine with phenol resulted in the formation of the following by-products: 2-iodophenol, 4-iodophenol, diiodophenols, and 2,4,6-triiodophenol. Most reaction conditions studied resulted in the formation of all or some of the specified iodophenols. The initial mass ratio of iodine to phenol was the major determining factor in the concentrations and types of by-products formed. The IDBPs were formed within one hour after initiation of the reactions. Extended reaction times did not lead to significant increases in the concentration of IDBPs. Under most reaction conditions, mono-subsituted phenols were detected at significantly higher concentrations than di-substituted phenolic compounds; triiodophenol was the major by-product when iodine:phenol mass ratio was 10:1. The greatest number of IDBPs were formed when reaction solutions consisted of 1:1 mass ratio of iodine to phenol. FPA panel indicated the odor threshold concentrations for phenol, 2-iodophenol, and 4-iodophenol were 5 mg/L, less than 1 ug/L, and 1 mg/L respectively. The most common odor descriptions for all these compounds were &quot;chemical&quot;, &quot;phenolic&quot;, and &quot;medicinal&quot;. / Master of Science

Disinfection by-products (DBPs) are a major group of water contaminants and their role in causing adverse health outcomes, including adverse pregnancy outcomes, endocrine disruption, respiratory related adverse health outcomes and cancer has been subject to extensive epidemiological and toxicological research and review. Determination of safe exposure to DBPs, particularly within drinking water supplies, has been a topic of extensive debate, with a wide range of acceptable levels set across the industrialized world. The focus of the research in this thesis was on two of the main health outcomes associated with DBP exposure, namely adverse pregnancy outcomes and asthma related symptoms. To assess adverse pregnancy outcomes in Perth, an extensive classification quantification of the major DBPs in Perth drinking water was conducted. A registrybased prevalence study was carried out to assess birth defects in relation to high, medium and low DBP areas (defined by the water sampling and analysis). It was found that women living in high THM areas are 22% (odds ratio (OR) 1.22, 95% confidence interval (95% CI) 1.01-1.48) more likely of having a baby with any birth defect. High exposure was also strongly associated with an increased risk of having a baby with a cardiovascular defect (62% increased risk). Low birth weight and prematurity were also assessed; however these outcomes were not associated with an increased risk through an increase in exposure. Following on from this analysis, a population risk assessment model was developed for DBPs in high exposure environments. This involved a three step process: (i) Firstly a questionnaire-based validation and reliability study was used to assess water consumption patterns of a population of pregnant women in Perth. (ii) Secondly a prediction model for teratogenic burden of DBPs in Perth was developed, related to the exposure patterns of the population of pregnant women involved in the validation and reliability study. (iii) Finally, combining the information collected in (i) and (ii), along with the regression slope estimates for birth weight from the prevalence study (defined in Section 2.2.1), a dose-response model for THMs and birth weight was developed. Predictive simulations for birth weights at given THM levels were then conducted. It was estimated that pregnant women in Perth are exposed to between 0.3 – 4.10 µg/day ingested TTHM, and of this, the more toxic brominated forms accounted for between 0.27 – 3.69 µg/day. Based on a dose-response model used, birthweights calculated for the ‘hypothetical’ exposures ranged from 3403.2g for the highest exposure to 3503.5g in the lowest exposure, which is a difference of over 100g. Although the resulting reduction in birth weight is not extreme, there is still a significant reduction in birth weight present as exposure to TTHMs increases. This is the first doseresponse model to be developed to assess an adverse pregnancy outcome based on pregnant women exposure data, and will be a useful tool for assessing varying exposures throughout not only Australia but also throughout the industrialised world, where DBP exposure is highly prevalent.

The emergence of pathogens that are more difficult to inactivate than bacteria, such as C. parvum and G. lamblia, has led to the enactment of more stringent drinking water regulations. The Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR), promulgated in January 2006, requires increased inactivation of C. parvum. However, increasing the disinfectant dose to enhance inactivation, especially when using chlorine, increases production of carcinogenic disinfection by-products (DBPs) such as trihalomethanes (THMs). As a result of the risks posed by DBPs, the Stage 2 Disinfectants and Disinfection By-Products Rule (Stage 2 D/DBP) was promulgated to limit exposure to DBPs by requiring systems to monitor concentrations at the worst cases locations in the distribution system. The purpose of this study was to evaluate sonication as an alternate disinfection strategy to reduce THM formation. Prior research has demonstrated the inactivation kinetics of sonication. Therefore, if sonication also reduces THM formation, this disinfection technology could help water utilities simultaneously comply with the Stage 2 D/DBP Rule and the LT2ESWTR. Water samples were prepared with varying concentrations of natural organic matter (NOM). THM formation potential reduction was evaluated by treating the water samples with sonication at 20 kHz for 0 seconds, 30 seconds, 60 seconds, 5 minutes and 10 minutes. After treatment, the samples were chlorinated and incubated at 20„aC to form THMs. After incubation times from 1 to 7 days, THMs were extracted, and gas chromatography with electron capture detection was used to quantify THM concentrations in treated and control samples. For experimental water with an NOM concentration of 1 mg/L that was dosed with 6 mg/L of NaOCl, the average THM formation potential reduction was 40% for sonication times of 30 seconds, 5 minutes and 10 minutes. The data for 60 seconds of treatment do not follow the same trends as the other data. Additional study is necessary to increase precision of the experimental data; however, this study supports sonication as a potential method of THM reduction.

Nanofiltration (NF) membrane technology is effective for removal of natural organic matter (NOM) and Disinfection By-Product (DBP) precursors from treated surface water (Allgeier et al., 1995, Chellam et al., 2000, Smith et al., 2002). However, there is a need to control other micropollutants, such as compounds released from algal blooms. In this research, the feasibility of using NF for removal of cyanobacterial exudates was evaluated as a polishing process for conventionally treated surface water. Screening tests were conducted to compare the performance of four NF membranes, Filmtec's NF90 and NF270, and Hydranautics's LFC1 and NTR7450, for removal of NOM and cyanobacterial exudates. The source water for the experiments was derived from Lake Manatee (FL) following full scale treatment by enhanced coagulation and dual media filtration. Water samples were amended with low levels of three cyanobacterial exudates: microcystin-LR, geosmin and 2-Methylisoborneol (MIB). The rapid bench scale membrane test (RBSMT) protocol was used to test NF at four recoveries of 50%, 70%, 85% and 95%. Bulk organics (TOC and UV254) and inorganics (conductivity, total and calcium hardness) were monitored along with other operating parameters during the setting and recovery tests. Spike tests were performed by spiking microcystin-LR (9.5 to 12.0 micro g/L), geosmin (45 to 220 ng/L) and MIB (45 to 225 ng/L). Three NF membranes (NF90, NF270 and LFC1) were effective for over 90% rejection of TOC and associated disinfection by-product formation potential (DBPFP). Due to NF treatment, the bromide:TOC ratio increased resulting in a shift towards higher levels of brominated DBPFPs. Similarly, these three NF membranes (NF90, NF270 and LFC1) were effective for removal of microcystin-LR to below the World Health Organization (WHO) guideline of 1 micro g/L. Only two of the NF membranes tested (NF90 and LFC1), were capable of removing geosmin and MIB to levels below the taste and odor threshold. These membranes removed greater than 92% of the geosmin and MIB. Based on these bench scale tests, further testing of NF on a pilot scale is warranted.

Bibliography: leaves 263-270.

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.