The concentrations of chlorine dioxide (CI02), chlorine, chlorite (CIO2), and chlorate (CI03) were evaluated following pretreatment of raw water by CI02 at water treatment plants in New Castle, Pennsylvania; Charleston, West Virginia; Skagit, Washington; and Columbus, Georgia. Chlorite and chlorate concentrations were unaffected by any of the water treatment processes and did not vary as a function of time of travel in the distribution system. Chlorine dioxide, which was analyzed on-site at two water treatment plants, reformed in the clear well and in the distribution system following post chlorination. The chlorite-removal capability of powdered activated carbon (PAC) was evaluated in both laboratory- and pilot-scale studies. Chlorite removal by PAC in laboratory studies decreased with increasing pH over a range from pH 5.5 to 7.5 and varied with the type of PAC. Chlorite was reduced to chloride at pHs ranging from 5.5 to 7.5, but CI03- formed at the pH 5.5 through 6.0. The pilot plant study; which was conducted at Newport News, Virginia; evaluated CI02 removal by PAC enmeshed in a floc blanket in a pulsed-bed, solids-contact clarifier. An average of 27 percent of the CI02 was removed when the PAC dose was 10 mg/L PAC and 57 percent when it was 20 mg/L PAC. Chlorate was not removed by PAC, but the concentrations could be reduced if the CIOz generator was properly operated. / Master of Science

Private wells are understudied potential sources of opportunistic pathogen (OP) infections. OPs, including Legionella and Mycobacterium, are of particular concern for immunocompromised individuals and are known to proliferate in drinking water systems. Much of our knowledge surrounding OP occurrence and growth in drinking water relates to municipal drinking water systems, which primarily use surface water sources and are always treated with primary and secondary disinfection in United States. However, OP occurrence and growth in private wells is not well understood and it is unclear how the knowledge developed in municipal systems will translate to private well systems with rare and infrequent exposure to chemical disinfectants. In addition, because private wells are more susceptible to microbial contamination than municipal systems, the impact of flooding on OP occurrence is of particular concern. Two private well field surveys were conducted to document the incidence of OPs in private well systems. One survey conducted in North Carolina private wells with no history of recent flooding was focused on molecular and culture-based detection of Legionella spp. and Legionella pneumophila. The other survey was a broader molecular (i.e., DNA-based) characterization of the incidence of Legionella spp., L. pneumophila, Mycobacterium spp., Mycobacterium avium (the most commonly nontuberculous mycobacteria associated with disease), and Naegleria fowleri in private wells with recent history of flooding (i.e., Hurricanes Harvey and Irma in 2017, or the Great Louisiana Floods in 2016, extending to Texas, Florida, and Louisiana). All samples in both studies were analyzed for total bacterial 16S rRNA genes, indicator bacteria (e.g., total coliform and Escherichia coli) and inorganic constituents. Information about well system characteristics were obtained through questionnaires sent to participating residents. Widespread detection of OP DNA markers were noted in the flooded well survey. Legionella spp. (detectable in 50-100% of well waters, depending on the flood event) and Mycobacterium spp. (detectable in 13.2-45.0% of well waters) were the most commonly detected among the OPs targets. At the genus level, L. pneumophila (7.9-65.5%) and M. avium (7.9-32.5%) were less commonly detected, but still highly variable. It is not possible to judge whether these OP levels were elevated as a result of the flooding because the sampling was carried out as an emergency response and background levels were not previously tested. Also of interest was whether well characteristics could predict OP levels, including well depth, well type, or treatment. However, none of these emerged as significant predictors of OP detection frequency or levels. Similarly, these OP DNA markers were not elevated in homes reporting submerged wellheads or system damage, suggesting that detection of these OPs is more dependent on the groundwater that supplies these private wells than influx of contaminated surface water. The incidence of DNA markers pertaining to N. fowleri, the "brain eating amoeba" that causes rare incidences of primary amebic meningoencephalitis (PAM), tended to be lower (5.0-12.7%) than that of other OPs targeted, but was more frequently detected in wells reporting submerged well heads, suggesting its occurrence was related to contamination from flood water. A positive association between total bacteria and occurrence of both Legionella spp. and Mycobacterium spp., was observed in private wells of all surveyed areas, contrary to observations in municipal drinking water systems with secondary disinfectant residuals. On the other hand, Legionella reportedly has an optimal growth range of 20-42 °C in municipal systems and recent surveys of municipal systems reported a strong association between Legionella spp. and temperature that was not observed for private wells in this study. We speculate that the essentially "infinite" water age and lack of disinfectant for well water, may contribute to these differences relative to municipal water supplies. The results presented in this work are likely an overestimation of OPs numbers in private wells, as molecular detection of OPs does not distinguish between live and dead cells. In addition, sample sizes were limited by laboratory throughput and budget. Identifying key variables impacting the occurrence of OPs in private wells, given that our study shows that these pathogens are relatively common, might someday help limit the risk of infections. / Master of Science / Non-fecal pathogens that are capable of growth in drinking water systems and causing illness primarily in individuals with compromised immune systems are referred to as opportunistic pathogens (OPs). OPs of concern in drinking water systems in the United States include members of the Legionella genus (i.e., Legionella spp.) and Mycobacterium genus (i.e., Mycobacterium spp.), as well as Naegleria fowleri (also known as “the brain-eating amoeba”). Much of our knowledge surrounding OP occurrence and growth in drinking water relates to municipal drinking water systems. Under the right conditions, OPs have the ability to grow in municipal drinking water systems and in building plumbing systems despite the use of disinfectants. However, OP occurrence and growth in private wells is not well understood and it is unclear how the knowledge developed in municipal systems translates to private well systems that rarely utilize chemical disinfectants. In addition, because private wells are more susceptible to microbial contamination than municipal systems, the impact of flooding on OP occurrence is of particular concern. Two private well surveys were conducted to document the incidence of OP DNA markers and culturable OPs in private well systems. The first survey was conducted in North Carolina private wells with no history of recent flooding and focused on quantification of DNA markers for Legionella spp. and L. pneumophila, as well as culturable L. pneumophila. The second survey was conducted in flood-impacted private wells in vi Texas, Florida, and Louisiana following Hurricanes Harvey and Irma in 2017 and the Louisiana Floods of 2016, quantifying five DNA markers for OPs (Legionella spp., L. pneumophila, Mycobacterium spp., M. avium, and N. fowleri). All water samples in both studies were also analyzed for total bacterial numbers (i.e., total number of copies of a gene present in all bacteria), certain bacteria that indicate environmental and fecal contamination (e.g. total coliform bacteria and Escherichia coli), and inorganics. Information about well system characteristics was obtained through questionnaires sent to participating residents. While it was not possible to sample before the flooding events and determine the background detection rates, this survey found that detection of the target OPs in the flood-impacted wells was widespread, but highly variable. Both culture-based and DNAbased testing methods were used to verify the results because each approach has strengths and weaknesses. Detection of DNA markers indicates the genetic material of the organism being tested for is present and detects DNA of organisms that are both dead and alive. Thus, DNA detection may overestimate the presence live (and infectious) pathogens. Detection of culturable pathogens indicates the organism is alive, but only detects pathogens that readily grow on culture media. There may be other pathogens in the water that do not readily grow on the media. Thus culture may underestimate the occurrence of pathogens. DNA markers for Legionella spp. (detectable in 50-100% of well waters) and Mycobacterium spp. (detectable in 13.2-45.0% of well waters) were the most commonly vii detected among the targets in this study. The detection of DNA markers for L. pneumophila (7.9-65.5%) and M. avium (7.9-32.5%) was less common. There were no private well characteristics, such as well depth, well type, or treatment that emerged as significant predictors of these OP detection or levels. Similarly, these OPs were not elevated in recently flooded homes reporting submerged wellheads or system damage. Thus, detection of these OPs was found to be widespread and sporadic. Detection rates of N. fowleri, which causes rare incidences of primary amebic meningoencephalitis (PAM), DNA was lower (5.0-12.7%) than other OPs, and was also not related to private well characteristics. However, N. fowleri DNA was more frequently detected in wells with wellheads that were submerged due to flooding than in wells with unsubmerged wellheads, as were total coliform bacteria (an indicator of environmental contamination) and total bacterial numbers. This demonstrates concern that submergence of wellheads during flooding is a concern for the introduction of microbial contamination in private wells. This work also explored two trends characteristic of municipal systems that were not observed in these surveys of private wells. First, positive associations between overall bacterial numbers and DNA markers for both Legionella spp. and Mycobacterium spp. were observed in private wells in all surveyed areas. This is contrary to what has been reported for overall bacterial numbers in municipal drinking water systems with a secondary disinfectant residual. Second, Legionella has been known to have an optimal growth range of 32 to 42 °C (90 to 108 °F) in municipal systems and recent surveys of municipal systems with both a free chlorine and chloramine secondary disinfectants viii showed a strong association between Legionella spp. and temperature. These associations were not observed in private wells in this work. Continuous disinfection treatment in municipal drinking water systems may eliminate certain microbes, lowering overall levels of bacteria, while OPs may persist by resisting disinfection, resulting in no correlation between total bacteria and OPs. Private wells do not generally use continuous disinfection and represent low-nutrient environments where naturally occurring OPs can grow alongside other bacteria. The results of this study are likely an overestimation of OPs infection risk associated with private wells, as infection can only be caused by live OPs, which cannot be directly determined by measuring DNA markers. In addition, sample sizes were limited by laboratory throughput and budget. Identifying key variables that impact the occurrence of OPs in private wells is necessary to minimize the risk of associated infections linked to private wells. This work provides strong preliminary evidence that OP occurrence in private wells is relatively commonplace. Science-based options for at-risk (e.g., immunocompromised) individuals to decrease their exposure to OPs in private well water need to be developed.

A <i>Pseudomonas</i> sp. capable of degrading tertiary butyl alcohol (TBA) as a sole carbon source, was isolated from a groundwater aquifer (50 ft. deep) at a petroleum refinery. The most probable number (MPN) of TBA degrading microorganisms was 4.9 x 10³ organisms/g (dry wt) of subsurface soil. Pristine subsurface soils, which did not have a history of petroleum contamination, had MPNs of < 2 TBA degrading organisms/g (dry wt) indicating a natural enrichment process at the refinery site. The Q_O2 of <i>Pseudomonas</i> sp. was 4.2 ml O₂/mg dry wt/h when TBA was the substrate. The optimum pH for growth was 7.0. The organism grew faster in continuous culture when TBA was the sole carbon source with a doubling time 33.6 h. The doubling time in batch culture was 112.3 h. When yeast extract was added to a mineral salts + TBA medium to concentrations greater than 1 mg/ml, TBA degradation was inhibited. When the yeast extract concentration was 0.1 mg/ml, a diauxy effect was seen in the growth rate. This suggested that TBA degradation by <i>Pseudomonas</i> sp. was subject to a regulatory mechanism. / M.S.

Chlorine dioxide has been used in drinking water treatment for the reduction of trihalomethanes and tastes-and-odors. Recently, chlorine dioxide was implicated as the source of offensive "cat-urine-like" and "kerosene-like" odors in drinking water. The purpose of this project was to determine the cause of odors observed in customers homes at times when chlorine dioxide was being applied to drinking water. Data were obtained through a survey and field sampling at utilities experiencing odor events. Once the cause was determined, potential water-treatment procedures were evaluated in laboratory-scale studies. Results from a survey sent to water utilities throughout the United States showed that customers who recently had installed new carpeting complained of odors more than those who had not. The use of chlorine dioxide caused responses to intensity of certain tastes-and-odors to increase, two of these odors were cat urine and kerosene. Field sampling at two water companies during odor events resulted in the discovery of low-levels of residual chlorine dioxide (0.2-0.7 mg/L) at the tap's of customers. Both the cat-urine- and kerosene-like odors were detected by the research team. To verify a proposed mechanism of odor generation, chlorine dioxide was volatilized in a room with new carpeting. Both odors were produced in amounts great enough to be easily detected by the entire panel. The removal of residual chlorite from drinking water would block a mechanism by which chlorine dioxide may be reformed from reactions between residual chlorite and free chlorine added for distribution system residual maintenance. Chlorite was removed by powdered activated carbon (PAC) enmeshed in alum floc in laboratory-constituted water and Po River water. A high level of PAC (50 mg/L) was required to effect good removal. A simulated floc-blanket clarifier effectively removed high levels of chlorite (>5 mg/L) from drinking water for long periods (12 hours) when PAC in high concentration was enmeshed in the floc. Chlorine dioxide reformed in the distribution system of two water companies. When customers opened water faucets, chlorine dioxide volatilized into the room and reacted with organic compounds present in the household air (e.g. from new carpeting) producing the offensive cat-urine-like and kerosene-like odors. The reformation of chlorine dioxide could be effectively eliminated if residual chlorite could be removed by contact with high levels of PAC enmeshed in an alum floc such as one could produce in a floc-blanket clarifier. / Master of Science

In the fields of water safety, food safety, and public communications, the overarching goal is to improve public health. Thus, this dissertation focuses on risk assessment and applying novel methods for exposure assessments and dose responses to contaminants in drinking water and foods. Factors that greatly impact contaminant exposures and human dose response include: population susceptibility (i.e., healthy adults or children), different routes of exposures (i.e., ingestion or inhalation), carrier matrices (i.e., water or food), and intricacies of chemical and biological mixtures. Chemical spills, such as the 2014 crude MCHM spill in Charleston, WV, revealed the complexities of both minor and major components in the chemical mixture. Slight shifts in geometric structures (isomers) can affect the fate and transport properties of the chemical mixture and as a result, the level of human exposure and dose response to each component in the chemical mixture. Odorous properties of both minor and major components can affect human inhalation exposure, especially during showering, and can be as detrimental as the ingestion route exposure and are different for healthy adults versus for children. Food contaminants, such as Shiga toxin producing Escherichia coli (STEC) in beef products, can be mitigated through a quantitative microbial risk assessment (QMRA) framework that follows a farm-to-fork model. Methods to ensure greatest microbial reduction include: employed intervention strategies at slaughter plants (i.e., water washing of beef carcass), improved cooking times and temperature methods at the consumer and retail level, and assessed minimum effective dose response modeling for different population susceptibilities. Current public communication tools, including the Drinking Water Taste-and-Odor Wheel or Consumer Confidence Reports (better known as water quality reports), should be redeveloped to uphold water safety. Furthermore, public health campaigns that uses social media strategies and informative websites can better educate the public on food contaminants. Ultimately, the objective is to prevent human illnesses due to water contaminants and foodborne pathogens and to bridge the communication gap between the consumers and the experts concerned with water and food safety. / Ph. D.

Robust decision support tools that aid water utilities to make informed, swift and precise decisions are becoming the need of the hour. Application of sophisticated models to aid the process of condition assessment and risk analysis on water pipelines have been limited owing to the lack of scalability, inability to incorporate external open source datasets and mathematically complicated output results. Interactive visualization of resultant model output is the key element in extracting valuable information to support decision making. This thesis presents a framework for visualization of data related to drinking water pipelines. Critical components of strategic, tactical and operational level decision making are explored in context with data presentation and information depiction. This thesis depicts various aspects of developing GIS web applications and their important functionalities for query and visualization of data. Multiple facets of data storage, standardization and application development are highlighted in this document. Publishing of application geo processing services in web environment is done through Virginia Tech enterprise geodatabase. Risk assessment and Performance models developed by a utility are projected in the application environment through help of widgets. Applications are coded into links on a Drupal website (www.pipeid.org) for model dissemination and utility engagement purposes. / Master of Science / Drinking water supply network primarily consists of pipelines, pumping stations, reservoir basins and treatment plants. Water pipelines are routinely inspected to check their condition and maintain appropriate water quality. Management of these subsurface assets should be given prime importance for maintaining high standards of services at acceptable cost to customers. An integral step in accomplishing this task is to view pipeline network in a geographic map. Different factors affecting pipeline condition are displayed on the map in the form of individual layers. Such real-world problems are analyzed with the help of Geographical Information System (GIS) tools that incorporate spatial features with tabular information. Moreover, interpretation of raw data into meaningful insights and distribution of allocated knowledge to all the concerned parties can be efficiently accomplished using rich internet applications. This thesis presents a framework to use GIS tools for developing web applications using raw data samples from contacted water utilities. Sample web applications are created and discussed in the form of case studies. Also, the challenges in water utility sector with respect to utilizing GIS tools for supporting daily decision-making processes is highlighted in this document. The recommendation to improve the suggested framework and adding more functionalities to developed applications are presented at the end with references.

The use of polymer pipes is now very common in home plumbing and other parts of the drinking water distribution system. Many taste and odor complaints in drinking water are known to originate from contact of water with materials. The ability of polymer pipes used in home plumbing to affect drinking water quality and aesthetics was investigated using the Utility Quick Test (UQT). Analysis of water quality and aesthetics were conducted in the absence of disinfectant and the presence of either chlorine or chloramines. A Flavor Profile Analysis (FPA) panel was trained according to Standard Methods 2170B to evaluate the organoleptic characteristics of the samples. Laboratory analyses were performed to determine levels of total organic carbon (TOC), disinfectant residual, pH and to attempt to identify specific volatile organics. The first part of this study investigated HDPE, cPVC and epoxy lined copper pipes using the UQT method. Both HDPE and epoxy-lined copper had significant effects on water quality and aesthetics during the approximately 10 day exposure of the UQT. HDPE and epoxy-lined copper leached significant amounts of TOC and consumed more disinfectant than controls, but in different amounts. cPVC was the most inert of the materials tested and had the least impact on water quality and did not contribute any significant odor. None of the pipes tested appeared to contribute trihalomethanes to drinking water, but further analysis revealed that the compounds may actually be generated and subsequently sorbed into pipe walls. These data show the effects of newly installed polymeric pipe materials and their potential to impact water quality in differing capacities. The second part of this study compared the results of the UQT on HDPE, epoxy lined copper, cPVC, PEX-a and PEX-b with the goal of comparing and contrasting how five different polymeric plumbing materials can impact drinking water quality. Results demonstrated the short-term ability of all pipe materials except cPVC to impact water quality and aesthetics. This data could potentially be useful in generating selection criteria for homeowners and plumbing professionals regarding the impact of newly installed plumbing materials. / Master of Science

Carbamazepine (CBZ) is an antiepileptic drug widely detected in drinking water supplies and wastewater effluent. It has been previously found that CBZ is recalcitrant to biological removal processes. Therefore, active CBZ will be exposed to wastewater effluent disinfection processes, which for most treatment plants in the United States involves the addition of free chlorine. However, the chlorination mechanisms of CBZ have not been fully investigated and are currently poorly understood. Our experimental studies were conducted to examine the chlorination of CBZ under controlled conditions. The kinetics, products, and reactivity of CBZ/free chlorine reactions were investigated over the pH range of 5.5-10. Results show that free chlorine reacts with CBZ and the reactivity is pH dependent. Furthermore, the results indicate that temperature affects the reactivity of CBZ with free chlorine. The temperature experiment results were fitted with the Arrhenius equation. The calculated Ea and A values are 48.8 kJ/mol and 1.41x104 s-1, respectively. Four common intermediates were detected based on both UV and mass spectral analysis proposed structures were developed based on m/z from mass spectra. / Master of Science

Virginia Tech researchers conducted a study to assist the Virginia Department of Health (VDH) in determining the policies and procedures necessary for the implementation of the United States Environmental Protection Agency final guidelines for the certification and recertification of small water system operators of community (CWS) and nontransient noncommunity public (NTNC) water systems serving under 3,300 people. A 42-question survey was developed and mailed to 2011 public water systems that serve 3,300 people or less. Survey results revealed that small systems in Virginia encompassed a diverse group of waterworks and owners/operators. Significant differences were found when survey results were analyzed by the number of people served and system category. Systems serving less than 100 people tended to not have a licensed operator, not have a full time employee, not meter their customers, and not have an operations and maintenance budget. As the system size increased, the likelihood of each increased. This research was supported by a grant from the Virginia Department of Health. / Master of Science

The dewatering of arsenic-containing residuals is a process that has received little study in the past. Arsenic that has been removed from water by sorption to ferric or aluminum hydroxides can accumulate in residuals to concentrations many times higher than in the source water. The first part of this study evaluates the effectiveness of lime conditioning as a method for immobilizing this arsenic. As the pH is increased with addition of caustic soda or soda ash, soluble arsenic concentration increases dramatically. However, as the pH is increased with lime, very little arsenic is released back into the water. On the basis of previous research this phenomenon might be attributed to the formation of a calcium arsenate solid. However, this study indicates it is more likely that the soluble calcium neutralizes the negative surface charge on the hydroxide solids at high pH and enhances arsenic sorption compared to when calcium was absent. In many cases arsenic-containing residuals are stored in lagoons and allowed to reside there for months or even years. Many parameters may affect the soluble arsenic concentration and speciation in these lagoons. The second portion of this study gives some baseline conditions for these lagoons, both with and without microbial activity and biological organic matter. In these practical situations it appears that lime can assist in keeping arsenic sorbed to the solids and prevent its release to the environment. / Master of Science