Water supply reservoirs are often subject to accelerated nutrient enrichment from urban sources. Cultural eutrophication due to such enrichment requires the development of efficient management and remediation strategies to protect drinking water sources. This study investigates the effects of using nitrate as part of a management strategy to control nutrient cycling in the Occoquan Reservoir in northern Virginia, USA. A novel aspect of the study is that the reservoir is part of an indirect potable reuse system where the source of nitrate is the product water from an advanced water reclamation facility (WRF). Field and laboratory studies showed that nitrate at a concentration greater than 1 mg/L N was effective in controlling the release of phosphorus, iron, and manganese from the sediments after the depletion of oxygen from the hypolimnetic waters of the reservoir. However, when the nitrate concentration above the sediment-water interface was less than 1 mg/L N, phosphorus, iron, and manganese release from the sediments was evident. Experiments revealed that the presence of nitrate decreased sediment ammonium release, but did not completely prevent it during anoxic periods. Results also showed that changes in the effective depth (ED) value along the length of the reservoir promoted higher denitrification rates in the upper reaches of the reservoir, thereby decreasing the downstream transport of nitrate. During periods of hypolimnetic anoxia, a nitrate-N input from the WRF of at least 10 mg/L N is needed to maintain an oxidized environment above the sediment-water interface. Therefore, decreasing the nitrate input to the reservoir will likely result in the deterioration of the surface water quality in the reservoir. Finally, the ED concept was proven to be an effective method to simulate different segments of the reservoir in laboratory-scaled experiments. Similarities between the field and laboratory results suggests that the environment that existed in the waters of the reservoir was closely replicated in the experimental setup, and provides confidence that laboratory results can be extrapolated to natural reservoir conditions. / Ph. D.

Land application of domestic wastewater effluent by rapid rate infiltration (i.e., percolation ponds) is a very successful and cost-effective method for wastewater management. Municipal percolation pond systems have been successfully operated in the United States for about 100 years. The disposal concept depends on a relatively high rate of secondary wastewater effluent infiltration into the soil by rapid percolation, either vertically or horizontally, away from the application surface area. This study was accomplished to determine infiltration rates at two working percolation pond systems and the variability of these rates, to compare the operating results with the initial design, and to create a stochastic computer based simulation program for design and operation. The initial study site was located west of Orlando, Florida, and consisted of a system of two percolation ponds. Daily readings were obtained on evaporation, rainfall, flow to the ponds, pond depth and groundwater table elevations. A mass balance inventory equation was formulated and the infiltration parameter was determined. A frequency distribution was created for the rainfall, evaporation and calculated infiltration from the initial site, and then a stochastic computer based simulation program was written with this data. The program calculated results which compared favorably with the design for this initial percolation pond site. A second site was chosen, also located in the Orlando area, to confirm the usefulness of the program and its operational capabilities.

As climate change exacerbates water scarcity and alters available water and fertilizer resources, it is vital that take appropriate measures to ensure sustainable treatment of water, wastewater, and other waste streams that are protective of public health and support recovery and reuse of water and nutrients. The overarching theme of this dissertation is the advancement of next-generation DNA sequencing (NGS) and computational tools for achieving these goals. A suite of relevant fecal and environmental opportunistic pathogens are examined using both culture-based and NGS-based methods. Of particular concern to this research was not only the attenuation and inactivation of pathogens, but also ensuring that optimal treatment approaches reduce antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). Key systems that were the focus of this effort included nutrient reuse (wastewater-derived biosolids and cattle-derived manure), water reuse, and drinking water systems disrupted by a major hurricane. A field study was carried out to survey a suite of pathogens from source-to tap in six small drinking water systems in Puerto Rico six months after Hurricane Maria. The study revealed that pathogenic Leptospira DNA was detected in all systems that were reliant on surface water. On the other hand, Salmonella spp. was detected in surface and groundwater sources and some distribution system waters both by culture and PCR. The study provided comparison of molecular-, microscopic-, and culture-based analysis for pathogen detection and highlighted the need for disaster preparedness for small water systems, including back-up power supply and access to chlorination as soon as possible after a natural disaster. A second field-study examined wastewater derived solids across an international transect of wastewater treatment plants in order to gain insight into the range of ARG concentrations encountered. It was found that, while total ARGs did not vary between treatment or continent of origin, clinically-relevant ARGs (i.e., ARGs encoding resistance to important classes of antibiotics used in humans) were significantly higher in solids derived from Asian wastewater treatment plants. Estimated loading rates of ARGs to soil under a scenario of land application were determined, highlighting in all cases that they are orders of magnitude higher than in the aqueous effluent. Livestock manure, derived from control cattle and cattle undergoing typical antibiotic treatment, and corresponding composts were also evaluated as common soil amendments in a separate study. In this study, the amendments were applied to two soil types in a greenhouse setting, in order to compare the resulting carriage of ARGs on a root (radish) versus leafy (lettuce) vegetable. Remarkably, radishes were found to harbor the highest relative abundance of total ARGs enumerated by metagenomics, even higher than corresponding soils or manures. Although the total microbial load will be lower on a harvested vegetable, the results suggest that the vegetable surface environment can differentially favor the survival of ARBs. The role of wastewater and water reuse treatment processes in reducing ARB and ARGs was also investigated at field-scale. Two independent wastewater treatment plants both substantially reduced total ARG relative and absolute abundance through biological treatment and settling according to metagenomic analysis. The subsequent water reuse treatment train of one system produced water for non- potable purposes and found further reduction in ARGs after chlorination, but a five hundred percent increase in the relative abundance of ARGs in the subsequent distribution system. In the second plant, which employed a membrane-free ozone-biologically-activated carbon-granular activated carbon treatment train for indirect potable reuse, there were notable increases in total ARG relative abundance following ozonation and chlorination. However, these numbers attenuated below background aquifer levels before recharge. Culture-based analysis of these systems targeting resistant ESKAPE pathogens (Escherichia coil, Staphylococcus aureus, Klebsiella spp., Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterococcus spp.) indicated similar trends as the metagenomic ARG analysis for both systems, but was challenged by sub-optimal media for wastewater samples and low confirmation rates, limiting statistical analysis. In order to advance the application of NGS, molecular, and associated bioinformatic tools for monitoring pathogens and antibiotic resistance in environmental systems, newly emerging methods and field standards for antibiotic resistance assessment were also evaluated. Hybrid assembly, the assembly for both short and long metagenomic sequencing reads, were assessed with an in silico framework in order to determine which available assemblers produced the most accurate and long contigs. Hybrid assembly was found to produce longer and more accurate assemblies at all coverages by reducing error as compared to short read assembly, though the outputs differed in composition from long read assembly. Where it is possible, it is beneficial to sequence using both long- and short-read NGS technologies and employ hybrid assembly, but further validation is recommended. Genome resolved metagenomics has also emerged as a strategy to recover individual bacterial genomes from the mixed metagenomic samples though this is often not well validated. In order to address this, genomes were assembled from reclaimed water systems and were compared against whole-genome sequences of antibiotic resistant E.coli isolates. Metagenome-derived genomes were found to produce similar profiles in wastewater treatment plant influents. A final theme to this dissertation addresses the need to standardize targets, methodologies, and reporting of antibiotic resistance in the environment. A systematic literature review was conducted on assays for the enumeration of key ARGs across aquatic environments and recommendations are summarized for the production of comparable data. In sum, this dissertation advances knowledge about the occurrence of pathogens, ARB, and ARGs across aquatic and agricultural systems and across several countries. Advances are made in the application of NGS tools for environmental monitoring of antibiotic resistance and other targets and a path forward is recommended for continued improvement as both DNA sequencing technologies and computational methodologies continue to rapidly advance. / Doctor of Philosophy / Understanding bacteria in our engineered systems is critical to ensuring drinking water, recycled water, and manure-derived soil amendments are safe for downstream applications. As novel approaches for assessing bacteria are developed, standardized methods and evaluations much be developed to ensure that sound conclusions are made that can appropriately inform policy and practice for the protection of public health. This dissertation focuses on combining bacterial culture and DNA sequencing methods for the study of pathogens (i.e., disease-causing organisms) and antibiotic resistance (i.e., ability of some bacteria to survive antibiotic treatments) in agricultural manure management, water reuse, and drinking water systems. Additionally, this work sought to advance emergent metagenomic analysis tools, which provides a new and potentially powerful pathogen and antibiotic resistance monitoring approach through direct extraction and sequencing of DNA from environmental samples. Antibiotic resistance is a global health challenge and it has been widely recognized that wastewater and agriculture are key control points. When antibiotics are ingested by people or livestock, they select for resistant bacteria in the gut. Mitigation efforts are needed, particularly at wastewater treatment plants and on farms, to ensure that excreted antibiotics and resistant bacteria do not further propagate and pose a risk. However, additional challenges such as climate change have spurred the need for more efficient use of our water and nutrient resources. In this work I examined how nutrient and water reuse treatment methods affect antibiotic resistant bacteria and antibiotic resistance genes using DNA sequencing as well as culture-based methods. In order to assess agricultural practices, a systems approach was conducted at the greenhouse scale to identify key control points to stem the spread of antibiotic resistance when vegetables are grown in soils amended with cattle-derived manure fertilizers. Along the food production chain, vegetables (i.e., radish and lettuce) were found to harbor higher proportions of bacteria carrying antibiotic resistance genes, although the estimated numbers of these bacteria were lower. Solids from an international transect of wastewater treatment plants (Sweden, Switzerland, USA, India, Hong Kong, Phillippenes) were examined because they are also foten used as soil amendments. DNA sequencing of these solids revealed that total measured antibiotic resistance genes did not vary between treatment or continent of origin. Calculations were made to determine the range of total hypothetical outputs of ARGs if the biosolids are land applied. Wastewater reuse systems were also examined using culture and metagenomic DNA analysis so that living pathogens could be compared alongside the total (dead and alive) antibiotic resistance genes. While standard wastewater and subsequent water reuse treatments were found to reduce the absolute numbers of antibiotic resistance genes and bacteria in a treatment plant producing water for non-potable reuse (i.e., irrigation), increases in culturable resistant pathogens and antibiotic resistance genes were apparent in the distribution system (i.e., in the pipes conveying treated water to the point of use). Similar reductions in antibiotic resistant bacteria and resistance genes were also seen in a plant using more advanced treatment (ozonation paired with biofiltration) to produce water suitable for indirect potable reuse via aquifer recharge, but there were indications that ozone and chlorine can increase the proportion of antibiotic resistant bacteria. Finally, genomes were recovered from the metagenomic sequencing analysis and were compared to sequenced culture isolates to validate the capabilities of metagenomic analysis to re-assemble genomes at the strain level, which is often required for pathogen confirmation. Pathogens were also assessed in disrupted drinking water systems in Puerto Rico after Hurricane Maria. Small scale systems that were disrupted by the storm were sampled to identify if pathogens were measurable six months after the hurricane. This work revealed that genes attributed to pathogenic Leptospira were detected in all surface water reliant systems while Salmonella spp. were detected by culture and DNA methods, but only in the source surface and groundwaters, not in the distribution systems delivering water to from the treatment site to the tap. This research also contributed to the advancement of big data analysis pipelines as well as to the standardization of methods to ensure that data produced across studies are comparable. Hybrid assembly, an emergent method that combines both short and long metagenomic DNA sequences generated by different technologies to more accurately recover genomes, was found to improve reliability and accuracy of algorithms aimed at reassembling DNA fragments. Antibiotic resistance is a global challenge, but without standardized methodologies for environmental monitoring, it will be difficult to compare measurements across countries and treatment processes in order to identify effective mitigation strategies. A critical literature review was conducted on assays for the enumeration of key antibiotic resistance genes across aquatic environments so that comparable data can be generated. This will be critical to tap into the tremendous volumes of antibiotic resistance monitoring data being generated around the globe to help identify trends and inform solutions. Collectively, this dissertation advances knowledge about the occurrence of pathogens, antibiotic resistant bacteria and antibiotic resistance genes across aquatic and agricultural systems while also critically evaluating emerging methods for the detection of antibiotic resistance in the environment.

Thesis (M.S.) -- Mississippi State University. Department of Electrical and Computer Engineering. / Title from title screen. Includes bibliographical references.

A água é um elemento vital para a vida, e em especial para a vida dos homens, os problemas causados pelo crescimento populacional e pelas mudanças de hábitos nas cidades, influenciam de forma determinante no “estado das águas". Volumes cada vez maiores de água são captados diariamente para o uso agrícola, industrial e urbano e uma vez utilizados são lançados ao meio ambiente. Muitas vezes transportam elementos contaminantes, esgoto doméstico e industrial, produtos químicos, metais pesados, e poluição difusa ausando impactos negativos imprevisíveis. Em muitos paises no mundo e o Brasil em regiões do semi-árido nordestino, e em especial nas regiões metropolitanas de São Paulo e Rio de Janeiro, um crescente déficit hídrico, impõe novas soluções de abastecimento de água. Este estudo busca soluções para um uso mais racional da água, um uso mais eficiente e que traga a economia de um bem cada vez mais precioso. Como mecanismos de economia de água, estudamos os dispositivos de micro-drenagem, a utilização de água da chuva para fins domésticos não potáveis. A adoção de mecanismos de reúso e de reciclagem da água, em atividades que permitam a utilização de uma água de menor qualidade, também são importantes ferramentas para a economia da água. Outra forma de utilização eficiente da água é o uso da água proveniente do rebaixamento dos lençóis freáticos para construção de 4 subsolos em edifícios, estes volumes, que em geral são diretamente bombeados e descartados na rede pluvial urbana, representam grande economia quando usados para fins não potáveis. Por fim uma análise dos aspectos jurídicos que condicionam o reúso da água. / Water is a vital element for life, especially for the human race. The problems caused by population growth and changes of habits in cities have a great influence in the “state of water supply" Increasing volumes of water are seized daily for agricultural, industrial and urban use and returned to the environment after that. Many times these water wastes have contaminating elements, industrial and residential sewage, chemical products, heavy metals and diffuse pollution that cause negative impacts of unknown intensity. In many countries and in Brazil’s semi-arid northeast region and, especially in the metropolitan areas of São Paulo and Rio de Janeiro a increasing deficit of water supplies call for new solutions in water supplying systems. The present study seeks for methods of rational use of water in an efficient way, in order to preserve an increasingly precious asset. The mechanisms for water saving studied in this dissertation are micro drainage systems and the use of rainwater for non-drinkable water uses. Adopting mechanisms of reuse and recycling of water in activities that can withstand the use of water of lower standards of quality are also important tools for water supply saving. Another method of efficient use of water is the use of undercurrent waters disposed for the construction of underground floors in buildings. These sources are usually pumped and discarded in the urban drainage systems, and if properly used for non-drinking purposes could help save great volumes of water. The study also includes an analysis of the juridical aspects that regulate water reuse.

A água é um elemento vital para a vida, e em especial para a vida dos homens, os problemas causados pelo crescimento populacional e pelas mudanças de hábitos nas cidades, influenciam de forma determinante no “estado das águas”. Volumes cada vez maiores de água são captados diariamente para o uso agrícola, industrial e urbano e uma vez utilizados são lançados ao meio ambiente. Muitas vezes transportam elementos contaminantes, esgoto doméstico e industrial, produtos químicos, metais pesados, e poluição difusa ausando impactos negativos imprevisíveis. Em muitos paises no mundo e o Brasil em regiões do semi-árido nordestino, e em especial nas regiões metropolitanas de São Paulo e Rio de Janeiro, um crescente déficit hídrico, impõe novas soluções de abastecimento de água. Este estudo busca soluções para um uso mais racional da água, um uso mais eficiente e que traga a economia de um bem cada vez mais precioso. Como mecanismos de economia de água, estudamos os dispositivos de micro-drenagem, a utilização de água da chuva para fins domésticos não potáveis. A adoção de mecanismos de reúso e de reciclagem da água, em atividades que permitam a utilização de uma água de menor qualidade, também são importantes ferramentas para a economia da água. Outra forma de utilização eficiente da água é o uso da água proveniente do rebaixamento dos lençóis freáticos para construção de 4 subsolos em edifícios, estes volumes, que em geral são diretamente bombeados e descartados na rede pluvial urbana, representam grande economia quando usados para fins não potáveis. Por fim uma análise dos aspectos jurídicos que condicionam o reúso da água. / Water is a vital element for life, especially for the human race. The problems caused by population growth and changes of habits in cities have a great influence in the “state of water supply” Increasing volumes of water are seized daily for agricultural, industrial and urban use and returned to the environment after that. Many times these water wastes have contaminating elements, industrial and residential sewage, chemical products, heavy metals and diffuse pollution that cause negative impacts of unknown intensity. In many countries and in Brazil’s semi-arid northeast region and, especially in the metropolitan areas of São Paulo and Rio de Janeiro a increasing deficit of water supplies call for new solutions in water supplying systems. The present study seeks for methods of rational use of water in an efficient way, in order to preserve an increasingly precious asset. The mechanisms for water saving studied in this dissertation are micro drainage systems and the use of rainwater for non-drinkable water uses. Adopting mechanisms of reuse and recycling of water in activities that can withstand the use of water of lower standards of quality are also important tools for water supply saving. Another method of efficient use of water is the use of undercurrent waters disposed for the construction of underground floors in buildings. These sources are usually pumped and discarded in the urban drainage systems, and if properly used for non-drinking purposes could help save great volumes of water. The study also includes an analysis of the juridical aspects that regulate water reuse.

<p>In the context of climate change, increasing demands for freshwater make it necessary to manage our water resources in a sustainable way and find innovative ways to extend their life. An integrated water management approach needs to consider anthropogenic water use and reuse which represent major components of the current water cycle. In particular, unplanned, or de facto, indirect water reuse occurs in most of the U.S. river systems; however, there is little real-time documentation of it. Despite the fact that there are national and state agencies that systematically collect data on water withdrawals and wastewater discharges, their databases are organized and managed in a way that limits the ability to combine reported water data to perform large scale analysis about water use and indirect reuse. To better document these issues and to demonstrate the utility of such an analysis, I studied the Wabash River Watershed located in the U.S. Midwest. Existing data for freshwater extraction, use, discharge, and river streamflow were collected, curated and reorganized in order to characterize the water use and reuse within the basin. Indirect water reuse was estimated by comparing treated wastewater discharges with stream flows at selected points within the watershed. Results show that during the low flow months of July-October 2007, wastewater discharges into the Wabash River basin contributed 82 to 121% of the stream flow, demonstrating that the level of water use and unplanned reuse is significant. These results suggest that intentional water reuse for consumptive purposes such as landscape or agricultural irrigation could have substantial ecological impacts by diminishing stream flow during vulnerable low flow periods. This research also completed a time series watershed-scale analysis of water use and unplanned indirect reuse for the Wabash River Watershed from 2009 to 2017. Results document the occurrence of indirect water reuse over time, ranging from 3% to 134% in a water-rich area of the U.S. The time series analysis shows that reported data effectively describe the water use trends through nine years, clearly reflecting both anthropogenic and natural events in the watershed, such as the retirement of thermoelectric power plants, and the occurrence of an extreme drought in 2012. Results demonstrate the feasibility and significance of using available water datasets to perform large scale water use analysis, describe limitations encountered in the process, and highlight areas for improvement in water data management.</p>

This study determined effects of addition of secondarily treated municipal wastewater effluent on an urban reservoir receiving system. Monthly water quality monitoring of the receiving reservoir and the wastewater, chemical analysis, and monthly laboratory algal assays, were conducted from September 1984 to September 1985. The nutrient status and algal growth potential of the receiving water and the wastewater confirmed the biostimulatory properties of the wastewater. Field validation studies were conducted using limnocorrals. Tertiary treatment of the wastewater using chemical coagulation precipitation with alum and ferric chloride reduced phosphorus concentrations in the wastewater to levels which supported significantly less algal biomass than untreated wastewater. These studies indicate ferric chloride to be a more effective coagulant for phosphorous removal alum.

Submitted in fulfillment of the academic requirements for the degree of Master of Technology in Engineering: Chemical Engineering, Durban University of Technology. Durban. South Africa, 2015. / The textile industry consumes large volumes of water and in turn produces substantial quantities of polluted effluents. Approximately 30% of reactive dyes used during the textile processing remain unfixed on fibres and are responsible for the colouration in effluents. Various conventional methods are being used to treat textile effluent. However, the disadvantage of these methods is that total colour removal is not achieved and chemical by-products are introduced from the use of chemicals. The water quality produced therefore does not meet the requirement for textile reuse. Membrane based processes provide interesting possibilities of separating hydrolysed dye stuff and dyeing auxiliaries, thereby reducing colouration and COD content. They can be employed to treat reactive dye bath effluent to recover the salts and water for the purpose of reuse. This study aimed at integrating membrane processes into the reactive dye bath of a textile industry. The objectives were to determine the quality of permeate produced in terms of removal of organics, ascertain its reusability for dyeing, investigate the production rate in terms of permeate fluxes and finally to investigate the cleanability and flux recovery of the membranes. Three effluent samples were chosen for this study based on the dyeing recipe; Light shade, Medium shade and Dark shade. Ultrafiltration (UF) and Nanofiltration (NF) membrane processes were employed to treat the reactive dye bath effluents to recover the salts and water. Investigations were conducted firstly with UF as a pre-treatment to NF. Secondly, evaluations were carried out on the performance of two types of NF membranes (SR90 and NF90) in terms of permeate quality and fluxes for the investigated samples. The effect of cleaning on membrane performance was done. A reusability test was carried out on the permeate samples for dyeing. It was found that the use of UF as a pre-treatment yielded an increase in permeate of 5–25% of the NF fluxes and 90% in organics reduction for all treated samples, hence increasing the water recovery. High rejection of ˃90% by NF90 for COD, TOC and colour were obtained for all the treated samples. SR90 rejection was 80–90% for colour and ˃90% for COD and TOC. Salt recovery for NF90 was 60–90% and for SR90 was 40–50%. The reusability tests carried out showed that permeate recycled from NF90 can be used for any section in the textile industry including the most critical such as dyeing on light shades, while that from SR90 can be used for dyeing dark shades only. It was then concluded that membrane based processes can be integrated into the dye bath of the textile process for the purpose of reuse, thereby saving on the cost of chemicals (salts), reducing fresh water usage and reducing the extent of final effluent treatment.

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management