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This research investigates organic polymers, inorganic coagulants and separate unit operations for their effect on the total tri-halogenated (TTHM) residuals in a finished water. The water samples utilized for this project were taken from a highly colored Central Florida potable water supply which is used by municipality which has a TTHM concentration in the finished water in excess of the proposed Federal limit. Results indicate that (1) organic polymers are not a significant source of THM precursors, (2) organic polymers, when used as a settling aid after coagulation in Jar tests, are an effective means of filtration for removing THM precursors, (3) THM residuals produced after coagulation increased directly with chlorination pH, (4) there was no significant difference in the THM precursor removal after coagulation for any coagulant tested and (5) coagulation removed a significant amount of THM precursor from the raw water.

Pharmaceuticals and personal care products (PPCPs) include a wide range of chemicals such as prescription and over-the-counter drugs, fragrances, diagnostic agents, and a litany of other compounds commonly added to household products such as sunscreens, soaps, toothpastes, and deodorants. If present in natural waters, PPCPs can come into contact with disinfectants during drinking water treatment processes. PPCPs are already known to form a variety of disinfection byproducts (DBPs) when oxidized by free chlorine, including trihalomethanes (THMs) and haloacetic acids (HAAs), many of which are known carcinogens. Salts, such as iodide, are also often present in natural water systems. Iodide is known to form a much more reactive oxidant, free iodine, when it reacts with free chlorine. Free iodine can react with organic compounds in waters to form iodinated byproducts, many of which have been shown to form in higher yields and to be more toxic than their chlorinated analogues. For this reason, it is necessary to more fully understand the fate of PPCPs during drinking water processes. The overall goals of this study are to 1) elucidate reaction mechanisms and product formation potentials for PPCP oxidation by free chlorine in the presence of iodide and 2) develop a computer model that can act as a predictive tool to aid in the assessment of potential risks resulting from PPCPs in source waters. Through the course of this research, a model was developed that could fit reaction rate parameters and accurately predict solution reactivity for a range of substituted phenols as well as PPCPs including bisphenol-A and triclosan. Past studies utilizing pseudo-first-order rate constants to determine a reaction rate over-simplified the analysis of halogen substitution reactions. Free chlorine reaction rate constant values were updated from the literature since the mechanism for electrophilic substitution was found to be different than stated in currently published literature. The involvement of H₂OCl⁺ was found to be negligible. The mechanism for the electrophilic substitution of phenolic compounds by free iodide was also different from current literature findings. We found that I₂, rather than H₂OI⁺, was an extremely important species for free iodine reactions and must be considered when analyzing the reaction kinetics. Finally, we found that small amounts of iodide can significantly affect product formation pathways thereby causing preferential formation of iodinated products and a potential increase in the total product formation. In general, the reaction kinetics were highly dependent upon the pH, iodide to free chlorine ratio, and the reactivity of the phenolic compound, and our model was able to successfully address changes in each of these variables. An LFER was developed that showed a linear relationship between reaction rates and the pK_a of a phenolic compound. It is believed that the model developed can be used as a predictive tool to estimate reactivity of natural waters for a range of phenolic PPCPs simply by using the compounds pK_a. / Ph. D.

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

Master of Science

Thousands of communities across the nation are exposed to health risks from contaminated drinking water. Upstream anthropogenic land covers have been linked with the degradation of source drinking water quality and likely pose a threat to a community water system's (CWS's) ability to provide safe drinking water. The goal of this study was to predict the differences in compliance with the Safe Drinking Water Act (SDWA) between CWSs based on their upstream land cover, economic situation, and system characteristics. In Central Appalachia, from 2001 to 2016, proportions of land cover in each target CWS's upstream source water watershed were weighted based on their distance to a CWS's source water intake. Violations to the SDWA at respective CWSs over the same period were modeled with their distance weighted land cover proportions, economic status of the county served, and system characteristics as covariates. The major findings were that increases in low intensity development increased the likelihood of a health-based violation, larger CWSs were less likely than smaller CWSs to obtain a monitoring and reporting violation, and CWSs that distributed purchased water were the least likely to incur either violation type. These results suggest that communities that have CWSs that are repeatedly failing to remain in compliance with the SDWA may be able to reduce public health risks associated with drinking water by purchasing from a larger CWS. Further to protect public health, community managers should consider source water protection and/or upgrading a CWS's treatment capacity prior to developing a previously undeveloped area. / Master of Science / Millions of people across the nation face health risks from contaminated drinking water. Understanding what factors influence a community water system's ability to supply safe drinking water is critical in the effort to protect public health. Land cover altered by humans has been found to pollute drinking water sources and may be linked to unsafe drinking water. This study aims to predict the differences in compliance with the Safe Drinking Water Act (SDWA) between community water systems (CWSs) based on their upstream land cover, economic situation, and system characteristics. In Central Appalachia, proportions of land cover between 2001 and 2016 were calculated for each target CWS's upstream source water watershed. Violations to the SDWA were used in a statistical analysis with land cover, economic status of the county served, and system characteristics of respective CWSs. The major findings were that increases in low intensity developed area increased the likelihood of health-based (HB) violations, larger CWSs were more likely than smaller CWSs to monitor and report their water quality, and CWSs that served purchased water were the least likely to have a HB or monitoring and reporting violation. These results suggest that purchasing drinking water from a larger CWS may allow water providers to reduce the risk to public health from unsafe drinking water. Additionally, protecting drinking source water and/or upgrading a CWS's treatment ability prior to developing a previously undeveloped area may reduce threats to drinking water safety.

Triclosan is a widely used antibacterial agent found in many personal hygiene products. While it has been established that pure triclosan and free chlorine readily react, interactions between triclosan-containing products and free chlorine have not previously been analyzed. Sixteen double-blinded solutions including both triclosan-containing (1.14-3.12 mg triclosan/g product) and triclosan-free products were contacted with free chlorine. Products detected included (chlorophenoxy)phenols, 2,4-dichlorophenol, 2,4,6-trichlorophenol, and chloroform. The daughter product yields were found to be highly variable and were dependent on the antimicrobial product investigated, the free chlorine to triclosan ratio, and the temperature at which the study was conducted. Lowering the temperature from 40 to 30 oC resulted in a decreased yield from 0.50 to 0.37 moles chloroform/mole triclosan after 1 minute of reaction time with [HOCl]initial = 4.0 mg/L as Cl2. Chloroform molar yields decreased to 0.29 when the initial chlorine concentration was reduced to 2.0 mg/L for a constant temperature of 40 oC. Field experiments, in which Atlanta and Danville tap waters were augmented with various soap products, exhibited differential results from the laboratory experiments in that different product yields were observed. These differences are attributed to the chlorine demand of constituents in the tap water. Higher chlorine to triclosan ratios tend to produce high levels of chloroform, while lower chlorine to triclosan ratios tend to form higher amounts of chlorophenols and (chlorophenoxy)phenol intermediates. The results from this study suggest that the chloroform produced by these reactions can be substantial under some conditions. / Master of Science

Corrosion of iron and copper pipes can produce leaks and loss of efficiency in the water distribution system, elevate levels of contaminants at the tap, and cost billions of dollars annually in pipe replacement or rehabilitation. In situ pipe rehabilitation using cement mortar, polyurethane, and epoxy is a commonly employed method of dealing with aging yet structurally sound pipes because it is less expensive and less invasive than replacing pipe infrastructure. Although epoxy has been shown to be an effective solution to pipe corrosion, little research has been conducted regarding its impact on a comprehensive list of water quality parameters. This research addressed that gap in the literature by conducting short-term immersion tests in which new epoxy linings were exposed to reference tap waters containing one of three disinfectant treatments: no disinfectant, free chlorine, or chloramines. As a comparison, an aged epoxy-lined field sample was also tested. Water exposed to the liners under stagnant conditions was analyzed for the following water quality parameters: pH, ammonia, alkalinity, hardness, metals, disinfectant consumption, total organic carbon (TOC), semi-volatile organic compounds (SVOCs), disinfectant byproduct (DBP) formation, and odor. Results of the study showed relatively low impacts on water quality, as all USEPA drinking water regulations were met. Impacts were highest during the first 24 hour exposure period during which time significant disinfectant consumption was shown (> 90% free chlorine consumed, 13% chloramines consumed), high TOC was leached (2.6-6.2 mg/L), trihalomethanes and haloacetic acids were formed (both < 15 ug/L), Bisphenol-A, an endocrine disrupter, was detected (< 35 ug/L), and odor was reported by panelists at a moderate intensity and described as sweet/chemical/burning/chlorinous. Impacts were much less after the initial 24 hours, although odor remained noticeable throughout the 30 day study. Overall, water quality impacts were greatest in chlorinated waters and both new and aged epoxy showed slight differences in results. / Master of Science

When well water becomes contaminated to the extent that is does not meet EPA drinking water quality standards, it is considered unsafe for consumption. Nitrate and total coliform bacteria are both health contaminants and are both regulated in public water systems. A nitrate concentration of 10 mg/L or higher is considered unsafe, as is the presence of total coliform bacteria. Well degradation, inadequate well construction, and aquifer contamination can all result in contamination of well water. Factors such as well type, well age, well depth, treatment devices, population density, household plumbing pipe materials, and nearby pollution sources may affect household water quality. The specific objective of this study was to determine which factors influence nitrate levels and total coliform presence/absence of household well water. If possible, these influencing factors would be used to develop a relationship that would allow household residents to predict the nitrate level and total coliform presence/absence of their well water. As a result, a means of predicting the contamination risk to a specific well water supply under a given set of conditions, in addition to increasing awareness, could provide the homeowner with a rationale for further investigating the possibility of contamination. Existing data from the Virginia Cooperative Extension Household Water Quality Testing and Information Program were assembled for analyses in this project. The data consisted of 9,697 private household water supplies sampled from 1989-1999 in 65 Virginia counties. Initially, the entire state of Virginia was analyzed, followed by the five physiographic provinces of Virginia: the Blue Ridge, Coastal Plain, Cumberland Plateau, Ridge & Valley, and Piedmont. Ultimately, Louisa County was investigated to evaluate the possibility that better models could be developed using smaller land areas and, consequently, less geological variation. Least squares regression, both parametrically and non-parametrically, was used to determine the influence of various factors on nitrate levels. Similarly, logistic regression was used to determine the influence of the same parameters on nitrate categories, presence/absence of total coliform, and risk categories. Using stepwise model-building techniques, based primarily on statistical significance (p-values) and partial coefficient of determination (partial-R2), first and second-order linear models were evaluated. The best-fitting model only explained 58.5% of the variation in nitrate and none of the models fit well enough to be used for prediction purposes. However, the models did identify which factors were, in a statistical sense, significantly related to nitrate levels and total coliform presence/absence and quantified the strength of these relationships in terms of the percent of variation explained. / Master of Science

A new regulation has been proposed that would lower the acceptable level of arsenic in drinking water from the current standard of 50 ppb. Therefore, research into effective arsenic removal treatment is important, especially for hard to treat waters with high concentrations of silica. The first phase of research was designed to determine if sand ballasted coagulation is a viable means of removing arsenic from drinking water, and if so, to identify the water qualities in which the technology performs best. A jar test protocol was developed and tested on a wide range of waters to compare microsand ballasted coagulation and other coagulation based treatment processes in terms of arsenic removal. Secondary impacts of the microsand process such as residual turbidity, iron, post-treatment membrane filter run length, and TOC removal were also considered as part of this evaluation. Microsand ballasted coagulation provided promising results for many of the simulated groundwater test conditions in which more than 80% of the arsenic regulation costs will be incurred. However, like conventional coagulation/sedimentation, microsand ballasted coagulation performed poorly in waters with high silica and high pH. Thereafter, a second phase of research more closely examined the kinetic behavior of arsenic sorption to amorphous and granular oxides in the presence of silica and calcium. At pH 8.5, calcium dramatically improved arsenic sorption to amorphous iron hydroxide in the presence of silica over short reaction times, but had no long-term advantage. This result could have considerable applications for treatment in that it suggests water quality controls the required reaction times. Additionally, batch tests indicated that activated alumina granular media was more sensitive to water quality than granular ferric hydroxide; however, calcium eliminated silica interference to arsenic sorption onto activated alumina. / Master of Science