No description available.

No description available.

The purpose of this investigation was to isolate and grow algae common to the southwest in unialgal culture; to either sustain or grow one of the principal bloom-causing organisms, with emphasis on Microcystis aeruginosa; to isolate and culture actinomycetes from the same waters from which the algae were obtained; and to inoculate these algae with actinomycetes and determine their effects through development and deterioration.

In an era of pervasive water stress caused by population growth, urbanization, drought, and climate change, limiting the dissemination of microbial contaminants of emerging concern (MCECs) is of the utmost importance for the protection of public health. In this dissertation, two important subsets of MCECs, opportunistic pathogens (OP) and antibiotic resistant genes (ARG), are studied across several compartments of the urban water cycle, including surface water, stormwater, wastewater, recycled water, and potable water. Collectively, this dissertation advances knowledge about the occurrence of OPs and ARGs across these water systems and highlights trends that may be of value in developing management strategies for limiting their regrowth and transmission. Field studies of two surface water catchments impacted by stormwater runoff demonstrated the prevalence of ARGs in urban stormwater compared to pristine, unimpacted sites, or to days when no precipitation was recorded. The role of wastewater reuse in transmitting OPs and ARGs was also investigated. Traditional tertiary wastewater treatment plants producing water for non-potable use were found to be largely ineffective at removing ARGs, but plants using advanced oxidation processes or ozonation paired with biofiltration to produce direct potable reuse water were highly effective at removing ARGs. Non-potable reclaimed water consistently had greater quantities of sul1, a sulfonamide ARG, and Legionella and Mycobacterium, two OPs of significant public health concern, present than corresponding potable systems. Limited regrowth of OPs and ARGs did occur in simulated premise (i.e., building) plumbing systems operated with direct potable reuse waters, but regrowth was comparable to that observed in systems fed with potable water derived from surface or groundwater. Advancements were also made in understanding the role of several hypothesized driving forces shaping the antibiotic resistome in natural and engineered water systems: selection by antimicrobials and other compounds, horizontal gene transfer, and microbial community composition. Finally, whole-genome and metagenomic characterization were applied together towards profiling L. pneumophila in clinical and water samples collected from Flint, Michigan, where an economically-motivated switch to an alternative water source created conditions favorable for growth of this organism and likely triggered one of the largest Legionnaires' Disease outbreaks in U.S. history. / PHD / Population growth, urbanization, drought, and climate change have all driven many U.S. municipalities to utilize alternative water sources, such as recycled wastewater, to offset demand on traditional potable water sources. Many water providers have moved towards a modern paradigm of utilizing multiple available water sources, recognizing the interconnectedness of various components of the urban water cycle, leading to opportunities to improve sustainability, optimize infrastructure use, stimulate economic growth, increase coordination among water agencies, and identify new water resources from which to meet consumer needs. Though advancements in treatment technologies throughout the twentieth century have largely succeeded in eliminating waterborne disease outbreaks associated with contamination of municipal water supplies by fecal pathogens in developed countries, several microbial contaminants of emerging concern (MCECs) have garnered attention. Two major groups of MCECs are considered in this dissertation: antibiotic resistance, including antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARG), and opportunistic pathogens (OP), such as Legionella pneumophila, the causative agent of Legionnaires’ Disease. ARB are a rising cause of disease around the world and are a major challenge to modern medicine because they make antibiotics used for treatment ineffective. OPs, the leading cause of waterborne disease in the U.S. and other developed countries, have become prevalent in engineered water systems where low nutrient concentrations, warm water temperatures, and long stagnation times can facilitate their growth. Immunocompromised people, including smokers and the elderly, are especially vulnerable to infection with OPs. The role of the urban water cycle in facilitating the spread of these MCECs is not well understood. Here they were studied across several compartments of the urban water cycle, including surface water, stormwater, wastewater, recycled water (spanning a variety of intended uses, from non-potable to direct potable reuse), and potable water. Field studies were conducted of two watersheds impacted by stormwater runoff, one in the arid Colorado Front Range under conditions of a rare, 1-in-1,000 year rainfall event, and one in the humid climate of southwest Virginia, during three summer storms. Both studies demonstrated the prevalence of ARGs in urban stormwater compared to pristine, unimpacted sites, or to days when no precipitation was recorded. The role of wastewater reuse in transmitting OPs and ARGs was also investigated. Wastewater treatment plants producing water for non-potable use (i.e. applications such as irrigation, but not for human consumption) were found to be largely inefficient at removing ARGs, and this reclaimed water consistently had greater quantities of the sul1 ARG present than in corresponding potable systems. In these systems, genes associated with the OPs Legionella and Mycobacterium as well as total bacteria were more abundant in reclaimed water than in corresponding potable systems. In more advanced treatment plants utilizing advanced oxidation processes or ozonation paired with biofiltration to produce direct potable reuse water (i.e. water fit for human consumption), ARGs were very effectively removed by treatment, with abundances often found to be higher in corresponding potable waters derived from surface or groundwater. Limited regrowth of ARGs as well as OPs did occur in simulated home plumbing systems operated with these waters, but regrowth was comparable to that observed in systems fed with potable water derived from surface or groundwater. Finally, a study of L. pneumophila in the Flint, Michigan drinking water system during use of an alternative water source that has been identified as a likely cause of two Legionnaires’ Disease outbreaks revealed presence of multiple strains of the OP in the system. Genomic comparisons revealed that strains isolated from hospital and residential water samples were highly similar to clinical strains associated with the outbreaks. Advancements were also made in understanding the role of several hypothesized driving forces in shaping the antibiotic resistome in natural and engineered water systems: selection by antimicrobials and other compounds, horizontal gene transfer, and microbial community composition. Together, these chapters describe an advancement in knowledge regarding the occurrence of OPs and ARGs in a variety of water systems, and highlight trends that may be of value in developing management strategies for limiting regrowth or transmission of these bacteria in various compartments of the urban water cycle.

Currently, water utilities are facing monetary crises to maintain and expand services to meet the current as well as the future demands. Standard practice in pipeline infrastructure asset management is to collect data and predict the condition of pipelines using models and tools. Water utilities want to be proactive in fixing or replacing the pipes as fixing-when-it-fails ideology leads to increased cost and can affect environmental quality and societal health. There is a number of modeling techniques available for assessing the condition of the pipelines, but there is a massive shortage of methods to check the reliability of the results obtained using different modeling techniques. It is mainly because of the limited data one utility collects and absence of piloting of these models at various water utilities. In general, water utilities feel confident about their in-house condition prediction and failure models but are willing to utilize a reliable methodology which can overcome the issues related to the validation of the results. This paper presents the methodology that can enhance the reliability of model results for water pipeline performance analysis which can be used to parallel the output of the real system with confidence. The proposed methodology was checked using the dataset of two large water utilities and was found that it can potentially help water utilities gain confidence in their analyses results by statistically signifying the results. / Master of Science / Water utilities are facing monetary crises to maintain and expand services to meet the current as well as the future demands. Standard practice in pipeline infrastructure asset management is to collect data and predict the condition of pipelines using models and tools. There is a number of modeling techniques available for assessing the condition of the pipelines, but there is a massive shortage of methods to check the reliability of the results obtained using different modeling techniques. This study presents the methodology that can enhance the reliability of model results for water pipeline performance analysis which can potentially help water utilities to be proactive in fixing or replacing the pipelines with confidence. Different types of analyses on the data received from the two large water utilities (name confidential) were performed to understand and check the application of the proposed methodology in the real world and was found that it can potentially help water utilities gain confidence in their analyses results by statistically signifying the result

In recent years, communities that source raw water from the Dan River experienced two severe and unprecedented outbreaks of unpleasant tastes and odors in their drinking water. During both TandO events strong 'earthy', 'musty' odors were reported, but the source was not identified. The first TandO event began in early February, 2015 and coincided with an algal bloom in the Dan River. The algal bloom was thought to be the cause, but after the bloom dissipated, odors persisted until May 2015. The second TandO in October, 2015 did not coincide with observed algal blooms. On February 2, 2014 approximately 39,000 tons of coal ash from a Duke Energy coal ash pond was spilled into the Dan River near Eden, NC. As there were no documented TandO events before the spill, there is concern the coal ash adversely impacted water quality and biological communities in the Dan River leading to the TandO events. In addition to the coal ash spill, years of industrial and agricultural activity in the Dan River area may have contributed to the TandO events. The purpose of this research was to elucidate causes of the two TandO events and provide guidance to prevent future problems. Monthly water samples were collected from August, 2016 to September, 2017 from twelve sites along the Dan and Smith Rivers. Multivariate analyses were applied to look for underlying factors, spatial or temporal trends in the data. There were no reported TandO events during the project but sensory analysis, Flavor Profile Analysis, characterized earthy/musty odors present. No temporal or spatial trends of odors were observed. Seven earthy/musty odorants commonly associated with TandO events were detected. Odor intensity was mainly driven by geosmin, but no relationship between strong odors and odorants was observed. / Master of Science / In recent years, communities that source water from the Dan River experienced two severe and unprecedented outbreaks of unpleasant tastes and odors (T&O) in their drinking water. During both odor events strong ‘earthy’, ‘musty’ odors were reported, but the source was not identified. The first event began in early February, 2015 and coincided with an algal bloom in the Dan River. The algal bloom was thought to be the cause, but after the bloom dissipated, odors persisted until May 2015. The odors returned in October, 2015 but did not coincide with an algal bloom. On February 2, 2014 approximately 39,000 tons of coal ash from a Duke Energy coal ash pond was spilled into the Dan River near Eden, NC. As no documented odor events occurred before the spill, there is concern the coal ash adversely impacted the water quality in the Dan River leading to the odor events. The purpose of this research was to elucidate causes of the two odor events and provide guidance to prevent future problems. Monthly water samples were collected from August, 2016 to September, 2017 from twelve sites along the Dan and Smith Rivers. Multivariate analyses were applied to look for important factors. There were no reported odor events during the project but sensory analysis characterized earthy/musty odors present. No temporal or spatial trends of odors were observed. Seven earthy/musty odorants commonly associated with odor events were detected.

In February 2014, a coal ash spill on Duke Energy's Dan River Plant in Eden, NC released approximately 39,000 tons of coal ash into the Dan River. It took approximately one week to stop the spill. Starting in February 2015, drinking water utilities using the Dan River experienced a series of taste and odor (TandO) events described as "earthy" or "musty". Similar TandO events were not documented before the coal ash spill. This research attempted to understand causes of the TandO events and if the coal ash spill was connected. A variety of water quality analyses were performed on twelve sites from August 2016 to September 2017 on the Dan and Smith Rivers. The Smith River served as the control. From concentrations of coal ash indicators (particularly Ba, Sr, As, V, and Br-), there was a signature of coal ash on the Dan River that was not present on the Smith River. The signature could not be attributed to the coal ash spill, as the signature was present upstream of the spill. Chronic ecosystem toxicity due to metals was low and not significantly different between the Dan and Smith Rivers. No substantial TandO events occurred during the period of this study. All monitored odorants were detected with varying frequencies in both the Dan and Smith Rivers. No significant change in odorant concentration was found above and below the location of the coal ash spill. / MS / In February 2014, a coal ash spill from Duke Energy’s Dan River Plant in Eden, NC released approximately 39,000 tons of coal ash into the Dan River. Starting in February 2015, drinking water utilities using the Dan River experienced a series of taste and odor (T&O) events described as smelling “earthy” or “musty”. Similar T&O events were not documented before the coal ash spill. This research attempted to understand underlying causes of these T&O events and to determine if the coal ash spill was connected. Analyses, including concentrations of coal ash indicators and odorants, were performed from August 2016 to September 2017 on a monthly basis for both the Dan and Smith Rivers. The Smith River served as a control river as it was not impacted by coal burning power plants and or a coal ash spill. There was a signature of coal ash metal contamination in the Dan River but not in the Smith River. The coal ash signature could not be attributed to the 2014 Duke Energy coal ash spill in Eden, NC because it was also found upstream of the area sampled and the location of the coal ash spill. Chronic ecosystem toxicity due to metals was low on the both the Dan and Smith Rivers and was not different between the rivers. No substantial drinking water taste and odor events occurred during the study period. All monitored earth-musty odorants were detected with varying frequency at concentrations mostly below and sometimes above their individual odor threshold concentration.

A rural-urban divide in health status and healthcare infrastructure has been well-documented in the U.S., where populations residing in census regions classified as rural often exhibit more negative health outcomes, adverse health behaviors, and have reduced access to affordable and proximal health services, compared to their urban and peri-urban counterparts. However, it is important to note that such disparities vary based on specific rural regions and individual circumstances. Rural areas may face elevated risk factors for infectious diseases such as increased proximity to wildlife and livestock and disproportionately high reliance on private, non-federally regulated, primary drinking water sources. Chronic conditions prevalent in rural communities such as diabetes and hypertension are frequently linked with longer duration and higher severity of symptoms than in urban areas; this association suggests that the risk of exposure to infectious diseases and the likelihood of progression to serious illness and hospitalization may be elevated, although this is not universally the case across all rural settings. Alongside documented urban-rural health disparities, there also exist disparities in the nature and quality of data on health-related behaviors, outcomes, and service provision in rural areas compared to urban and peri-urban regions. In this dissertation, two key environmental matrices –drinking water and wastewater– were highlighted as vectors of information to better estimate levels of contaminant exposures and health outcomes in rural communities. First, baseline data on drinking water contaminant levels and associated health outcome data were highlighted as crucial for refining holistic exposure estimates as well as understanding drinking water related health burdens in rural communities where a larger proportion of households use private drinking water sources, such as well water, that are not federally regulated. Second, systematic sampling and testing of pathogen biomarkers in wastewater to non-invasively measure population-level health status, also known as wastewater based surveillance (WBS) and, depending on the context, wastewater based epidemiology (WBE) is not constrained by disadvantages of clinical testing, e.g., limited health-care access, long travel times to testing facilities, delay between symptom-onset and testing. Thus, expanded implementation of WBS in rural communities is proposed here as a strategy to address data disparities in clinical testing for infectious diseases. Collectively, this dissertation advances knowledge on estimated drinking water contaminant levels, exposures, and associated public health outcomes and corresponding research gaps in rural Appalachian U.S., and elucidates pathways toward best practices and considerations for public-health focused wastewater testing adoption in rural communities. For the latter, the question of whether WBS challenges unique to rural wastewater systems hinder application of WBS in small, rural communities was explored, as well as methods to advance best-practices for rural WBS. To summarize existing publicly available peer-reviewed literature on drinking water contaminants in rural Appalachian U.S., in Chapter 2, a systematic review and meta-analysis of microbial and chemical drinking water contaminants was performed. Key contaminants were identified as being elevated beyond regulatory, health-based, maximum contaminant levels in our meta-analyses from rural drinking water sources in Appalachia, including E coli, lead, arsenic, uranium. Overall, we found data on drinking water source quality under baseline conditions (i.e., rather than post anomalous contamination events such as chemical spills) in rural Appalachian U.S. was sparse relative to widespread media coverage on the issue. Epidemiologic-based research studies that collected both drinking water exposure data and paired health outcome data were also limited. As a result, although some instances of anomalously high levels of drinking water contaminants were identified in rural Appalachia from the published literature, we could not obtain a clear picture of baseline exposures to drinking water contaminants in most rural Appalachian communities, highlight need to address these knowledge gaps. In Chapter 3, to evaluate whether wastewater could serve as a reliable metric for estimating community circulation of viruses and antimicrobial resistance (AMR) markers, even when sourced from aging and low-resource sewer collection networks, a 12-month wastewater monitoring study was conducted in a small, rural sewer conveyance system with pronounced infrastructural challenges. Specifically, the field site under study was compromised with heavy inflow and infiltration (IandI). Detection rates and concentrations of viral, AMR, and human fecal markers were grouped by levels of IandI impact across the sewershed, and location-, date-, and sample- specific variables were assessed for their relative influence on viral, AMR, and human fecal marker signal using generalized linear models (GLMs). We found that while IandI likely adversely impacted the magnitude of wastewater biomarker signal to some extent throughout the sewershed, especially up-sewer at sites with more pronounced IandI, substantial diminishment of wastewater signal at WWTP influent was not observed in response to precipitation events. Thus, our data indicated that WWTP influent sampling alone can still be used to assess and track community circulation of pathogens in heavily IandI impacted systems, particularly for ubiquitously circulating viruses less prone to dilution induced decay. Delineations were also made for what circumstances up-sewer sampling may be necessary to better inform population shedding of pathogens, especially where IandI is prevalent. Various normalization strategies have been proposed to account for sources of variability for deriving population-level pathogen shedding from wastewater, including those introduced by IandI-driven dilution. Thus, in Chapter 4, we evaluated the temporal and spatial variability of viral and AMR marker signal in wastewater at different levels of IandI, both unnormalized and with the adoption of several normalization strategies. We found that normalization using physicochemical-based wastewater strength metrics (chemical oxygen demand, total suspended solids, phosphate, and ammonia) resulted in higher temporal and site-specific variability of SARS-CoV-2 and human fecal biomarker signal compared to unnormalized data, especially for viral and AMR marker signal measured in wastewater from sites with pronounced IandI. Viral wastewater signal normalized to physicochemical wastewater strength metrics and flow data also closely mirrored precipitation trends, suggesting such normalization approaches may more closely scale wastewater trends towards precipitation patterns rather than per capita signal in an IandI compromised system. We also found that in most cases, normalization did not significantly alter the relationship between wastewater trends and clinical infection trends. These findings suggest a degree of caution is warranted for some normalization approaches, especially where precipitation driven IandI is heightened. However, data and findings largely supported the utility of using human fecal markers such as crAssphage for normalizing wastewater signal to address site-specific differences in dilution levels, since viral signal scaled to this metric did not result in strong correlations between precipitation and wastewater trends, higher spatial and temporal variation was not observed, and strong correlations were observed between viral signal and viral infection trends. Finally, in chapter 5, we assessed the relationship between monthly Norovirus GII, Rotavirus, and SARS-CoV-2 wastewater trends with seasonal infection trends for each of the viruses to ascertain whether WBE could be used in a rural sewershed of this size with substantial IandI impacts to track and potentially predict population level infection trends. Though up-sewer, or near-source sampling, at sites with permanent IandI impacts did not exhibit a clear relationship with seasonal infection trends for Rotavirus, SARS-CoV-2, and Norovirus GII, WWTP influent signal and consensus signals aggregated from multiple up-sewer sites largely mirrored expected seasonal trends. Findings also suggested that for more ubiquitous viral targets, such as SARS-CoV-2, viral trends measured at WWTP influent in a small IandI impacted system may still provide a sufficiently useful measure of infection trends to inform the use of WBE (assuming appropriate normalization to sewershed population). These findings elucidate the potential utility and relative robustness of wastewater testing to ascertain community-level circulation of pathogens in small, rural sewersheds even those compromised by extensive IandI inputs. Overall, this dissertation examined drinking water and wastewater as critical metrics for assessing contaminant exposures and infectious disease trends in rural communities, particularly in the context of small, rural communities which tend to have more limited health infrastructure and lower-resource wastewater systems. Overall, findings underscore the need for baseline data on drinking water quality by identifying gaps in current knowledge and calling for further research to better understand drinking water contaminant exposure levels in rural areas. Wastewater as a non-invasive, population-level health metric was evaluated in the context of a small, rural sewer system overall, and by varying observed levels of IandI, as well as associated tradeoffs for normalization adoption. By evaluating these environmental surveillance metrics using both desk-based and field-based research study designs, findings from this dissertation offer valuable insights and practical recommendations for improving baseline drinking water quality monitoring and wastewater pathogen testing, all with the overarching goal of supporting more targeted public health interventions in rural settings. / Doctor of Philosophy / In the United States, there is a significant health and healthcare gap between rural and urban areas. Rural communities often face worse health outcomes, poorer health behaviors, and have less access to affordable and nearby healthcare services compared to their urban and peri-urban counterparts. Additionally, rural areas are exposed to higher risks for infectious diseases due to closer proximity to wildlife and livestock and proportionately lower access to regulated drinking water sources. Chronic conditions like diabetes and hypertension, which are more common in rural populations, can exacerbate the severity and duration of symptoms for infectious diseases, potentially leading to more serious illness and hospitalizations. Despite these heightened risks, data on health behaviors, outcomes, and healthcare services in rural areas is often lacking and less comprehensive compared to urban regions. This dissertation investigates two promising avenues of improving monitoring to provide information needed to better understand and address contaminant exposures and health trends in rural communities: drinking water and wastewater. Firstly, this dissertation underscores the importance of establishing baseline data on drinking water quality. This is essential for accurately estimating exposure levels and understanding the health impacts associated with elevated levels of drinking water contaminants, particularly in rural areas where a higher share of primary drinking water sources is unregulated by the federal government compared to urban areas. This study reveals significant gaps in current knowledge and highlights the need for more research to provide a clearer picture of drinking water quality in these communities. Secondly, this dissertation explores the use of wastewater as a non-invasive tool for assessing community health. This method, known as wastewater-based surveillance (WBS) or wastewater-based epidemiology (WBE), offers a way to measure population-level health trends without relying on clinical testing, which can be limited by factors such as access to healthcare and delays in testing. The dissertation evaluates how effective wastewater monitoring can be in small, rural sewer systems, even when these systems face challenges like aging infrastructure and significant inflow and infiltration (IandI) from groundwater and surface water. It examines how different normalization strategies for wastewater data can influence the reliability of this method and how wastewater testing can be adapted to account for varying levels of IandI. Overall, the dissertation provides valuable insights into the effectiveness of using drinking water and wastewater as environmental metrics for informing public health intervention strategies in rural settings. It offers justifications for improving drinking water quality monitoring and wastewater testing practices, aiming to support more targeted and effective public health interventions in rural communities. By addressing the challenges and limitations associated with these environmental monitoring strategies this research contributes to a better understanding of how to reduce health data disparities in rural areas.

Evaluation of the sources and cycles of water quality contaminants in watersheds is critical for effective surface water resource management. In particular, iron (Fe) and manganese (Mn), commonly found in rocks and sediments, have adverse impacts on water quality. However, controlling Fe and Mn in surface water systems is often complex and requires careful consideration of the hydrologic and biogeochemical factors that influence the speciation and mobility of these metals. This dissertation investigates the sources and cycles of Fe and Mn in surface waters designated for human use. Here, I present the findings from three field- and laboratory-based studies conducted at sites in western Virginia, United States. The first study examines the impacts of reservoir-derived and watershed-derived metals on water quality along the 180 km reach of the Roanoke River downgradient from Leesville Dam. The results from this study showed strong temporal influences on river water quality immediately downgradient of the dam, resulting from seasonal reservoir dynamics. Further downgradient in the Roanoke River, water quality was strongly tied to hydrologic conditions resulting from influences generated in the watershed. The second study investigated the effects of increasing dissolved oxygen (DO) concentrations in the hypolimnion of stratified drinking water reservoir on Fe and Mn oxidation and removal. Results from a whole-ecosystem experiment showed that increasing DO concentrations through hypolimnetic oxygenation was effective for preventing the accumulation of soluble Fe in the water column. Although Mn oxidation increased under well-oxygenated conditions, soluble Mn still accumulated in the hypolimnion. Results from a laboratory experiment demonstrated that the oxidation of Mn was strongly tied to the activity of Mn oxidizing microbes. The third study examined the relative contribution of external and internal metal loadings to the exchange of metals between sediments and the water column and the source/sink behavior of a seasonally stratified reservoir under varying hydrologic conditions in the inflows and outflows and redox conditions in the reservoir hypolimnion. Results from this study showed that redox conditions strongly influenced the exchange of metals between the sediment and aqueous phase, but had little effect on the source/sink behavior of the reservoir, while external tributary loadings had little effect on internal redox cycles, but was a strong indicator for whether the reservoir behaved as a net metal source or sink. Overall, the findings from these studies exemplify the value of characterizing the hydrologic and biogeochemical drivers of Fe and Mn cycles for managing the water quality effects of these metals in surface water supplies. / Ph. D. / Identifying where drinking water contaminants come from and how they change in river, lake, and reservoir environments is critical for effectively managing surface water resources. In particular, the metals iron (Fe) and manganese (Mn), which are commonly found in rocks and sediments, can pose water quality problems. Controlling Fe and Mn in surface waters requires knowledge of flow conditions and water chemistry, which can both influence how these metals are transported and whether they will reach problematic levels. This dissertation investigates the sources and chemical cycles of Fe and Mn in surface waters designated for human use. Here, I present the findings from three fieldand laboratory-based studies conducted at sites in western Virginia, United States. The first study examines temporal and spatial patterns of Fe and Mn concentrations along the 180 km reach of the Roanoke River downstream from Leesville Dam. The results from this study showed that the chemistry of Leesville Lake, which varies seasonally, is an important influence on the concentration of Fe and Mn in the river just downgradient from the dam. Further downstream in the Roanoke River, metal concentrations in the river were strongly tied to flow conditions in the streams that originate in the watershed and flow into the Roanoke River. The second study investigated the effects of increasing dissolved oxygen (DO) concentrations in a drinking water reservoir on the chemical oxidation and removal of Fe and Mn in the reservoir. Results from a whole-ecosystem experiment showed that increasing DO concentrations in the reservoir using an oxygenation system was effective for preventing the accumulation of dissolved Fe in the water column. Although Mn oxidation increased under when DO concentrations were high, soluble Mn remained problematic in the reservoir. Results from a laboratory experiment demonstrated that the oxidation of Mn was strongly tied to the activity of Mn oxidizing microbes. The third study examined the effects of DO concentrations in a drinking water reservoir and flow conditions in the major stream flowing into the reservoir on the transfer of Fe and Mn between the reservoir water and sediments. We also examined how stream discharge and DO concentrations in the reservoir influenced the net transfer of metals into or out of the reservoir. Results from this study showed that DO concentrations strongly influenced the transfer of metals between the reservoir water and sediment, but had little effect on the net transfer of metals into or out of the reservoir, while flow conditions in the inflow stream had little effect on metal transfer between the reservoir water and sediments, but was a strong indicator for whether there was a net transfer of metal into or out of the reservoir. Overall, the findings from these studies exemplify the value of characterizing the hydrologic and biogeochemical conditions that effect Fe and Mn for managing water quality in drinking water supplies.

Submitted in fulfillment of the requirements for the degree of Master of Engineering in Chemical Engineering, Durban University of Technology. Durban. South Africa, 2015. / Several areas in the world such as the United States of America, Sri Lanka, China, Argentina, Canada, Tanzania, Kenya, South Africa and many others have a problem of high fluoride content in drinking water. Generally fluoride levels above 1.5 ppm in water may result in dental and skeletal fluorosis in humans depending on quantity consumed (Fan et al., 2003; Meenakshi, 2004). Remote rural areas where there are no water treatment facilities are more vulnerable to this problem. Adsorbents such as activated alumina and FR-10 resin seem to have a potential for successful application in rural areas. These methods however require pre-treatment if the feed has high turbidity. A membrane based system called woven fabric microfiltration gravity filter (WFMFGF) developed by Durban University of Technology proved to be suitable for turbidity removal. The main objective of this research was to develop a small water treatment system for fluoride removal. The small water treatment system developed in this study consists of WFMFGF for pre-treatment and an adsorption column. The WFMFGF is made up of a 40 L container packed with 15 immersed flat sheet membrane elements. The operation of the WFMFGF is in batch mode, driven by varying static head. The static head variation results in flow rate variation through the system. This in turn result in variation of contact time, velocity as well as pressure drop in the fluoride removal unit. Specific objectives of the study were: (1) to establish the maximum and minimum flow rates through the WFMFGF system, the total run time before cleaning is required and the best cleaning method for this particular membrane system. (2) to evaluate and compare the performance of activated alumina and FR-10 resin on varying contact time, velocity and pressure drop on the fluoride removal unit. The adsorbents were also compared on adsorption capacity, cost and ease of operation. The minimum and maximum flow rates through the WFMFGF were found to be 5 l/hr and 100 l/hr respectively. It was found that the system can be run for more than a month before requiring cleaning. The suitable cleaning method was found to be soaking the membranes in 0.0225 percent sodium hypochlorite solution overnight and brushing them using a plastic brush. The comparison of the performance of FR-10 resin to activated alumina found that the adsorbents gave equal performance based on the given criteria. FR-10 resin had higher adsorption capacity, gave good quality treated water even with shorter contact time and operated at wider velocity range. Activated alumina on the other hand had an advantage of lower costs, lower pressure drop and ease of use. According to Pontius (1990), the performance of activated alumina can be improved by intermittent operation. Point of use (POU) systems are generally operated intermittently. This improves the fluoride removal efficiency of activated alumina giving it more advantage over FR-10 resin. Based on this activated alumina was selected as the best adsorbent for the system. After the adsorbent was selected, the adsorption column was designed. The column operation regime was 3.5 minutes minimum contact time and 1.17 to 7.8 m/hr velocity range. The activated alumina adsorption capacity was 1.53mg/g. The column had an inside diameter of 70 mm. It was packed with activated alumina to a bed height of 400 mm. The column inlet and outlet pipes were made of PVC with a standard pipe size of 20 mm outside diameter. A valve at the column inlet pipe allowed water to flow through the system.