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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Understanding Practical Limitations of Lead Certified Point of Use (POU) Filters

Rouillier, Rusty Jordan 27 July 2020 (has links)
There has been a recent increase in the adoption of point-of-use (POU) household water filters as an alternative to untreated tap water or bottled water. POU filters certified for lead removal have recently been distributed by the hundreds of thousands in communities amid water lead crises, as a temporary solution to protect consumers from elevated water lead levels. This thesis rigorously examines the efficacy of POU lead certified filters in removing lead under a wide range of conditions, and evaluates premature clogging due to iron and associated impacts on the cost analysis of using filters instead of bottled water. In testing ten brands of POU devices against up to four different waters for lead removal, most devices consistently removed lead to below the 5 µg/L FDA bottled water standard. However, several failures were documented, including manufacturing flaws, premature clogging, and inconsistency between duplicate filters. When waters containing more difficult to treat lead particulates were synthesized, treated water often had lead concentrations greater than the 5 µg/L bottled water standard and sometimes were even over the 15 µg/L EPA action level. In some cases, less than 50% of the particulate lead was removed by the filter, thereby replicating some problems with these devices identified in the field. While POUs usually reduced water lead concentrations by at least 80%, a combination of manufacturing issues and difficult to treat waters can cause treated water to exceed expectations. Consumers often purchase POU devices to remove particles and lead in waters that also contain high iron, prompting studies to examine the role of iron on filter performance. When we exposed two brands of pour-through POUs to waters with both high lead and iron, lead removal performance was generally not compromised, as treated water typically had lead concentrations less than 5 µg/L. One case was observed in which lead passed through a set of filters at high levels in association with iron, confirming expectations that in some waters iron could cause formation of lead particulates that are difficult to remove. High levels of iron sometimes rapidly clogged the POU filters, preventing them from reaching their rated capacity and increasing operational costs and time to filter water. Specifically, 50% (3/6) of the filters tested clogged prematurely at an iron concentration of 0.37 mg/L, 66% (4/6) at 1 mg/L and 100% (6/6) at 20 mg/L. A cost analysis for POUs vs. bottled water demonstrated that in waters with higher iron, store-brand bottled water was often the more cost-effective option, especially when iron levels were significantly higher than the EPA Secondary Maximum Contaminant Level (0.3 mg/L). The lower costs of bottled water in these situations was even more apparent if consumer time was factored into the analysis. / Master of Science / There has been a recent increase in the use of household water filters as an alternative to tap water or bottled water. Filters that are certified for lead removal have recently been distributed by the hundreds of thousands in communities amid water lead crises, as a temporary solution to protect consumers from elevated water lead levels. This thesis rigorously examines the effectiveness of these filters under a wide range of conditions. When tested against up to four different waters for lead removal, most filters consistently reduced lead to below the concentrations allowed in bottled water. In cases where the filters did not perform as expected, several filter failure modes were identified, including manufacturing flaws, filter clogging, and inconsistency between duplicate filters. In addition to these failures, when a water that contained particulate lead that was difficult to filter, as little as 50% of the lead was removed. While household filters often significantly reduce water lead concentrations, a combination of manufacturing issues and difficult to treat waters can cause poor performance. In many cases, consumers purchase filters to remove particles or lead in waters that also contain iron, which caused us to investigate the effect of iron on filter performance. When two brands of pour-through filters were tested against waters with both lead and iron, lead removal performance was generally not compromised. One exceptional case was observed where both high levels of lead and iron passed through the filters, leading us to believe that iron in some waters could create conditions where lead is more difficult to remove. In many cases, the presence of iron caused filters to dramatically slow down or clog. Premature clogging due to iron prevented filters from reaching their rated capacity and, in doing so, significantly increased cost and filter times. A cost analysis for filters vs. bottled water demonstrated that in waters with higher iron, store-brand bottled water was often the more cost-effective option, especially in waters with higher levels of iron. The lower costs of bottled water in these situations was even more apparent if consumer time was factored into the analysis.
22

Design and Case Study Application of a Participatory Decision-making Support Tool for Appropriate Safe Water Systems Development in Marginalized Communities of the Global South

Ali, Syed Imran 18 June 2012 (has links)
This dissertation presents the design and case study application of a participatory decision-making support tool for appropriate safe water systems development in marginalized low-income communities of the global South. The tool focuses on the resolution of two key design decisions: 1) selecting the appropriate level of application (i.e. household or community level) for a safe water system; and 2) selecting an appropriate water treatment technology (or technologies). The tool breaks the process down into four stages. First are pre-implementation steps which develop a contextualized, baseline understanding of the local community. Second is community-based field research, including focus groups and key informant/informal interviews, to investigate the two key design questions by exploring local preferences, capacities, and circumstances with community-members, government officers, NGO workers, and other stakeholders. Third are analytical steps to integrate information from baseline, informal, and primary research to generate recommendations on the two key design questions. This includes a comparative analysis of household and community level systems; a technology feasibility flowchart; performance assessments of technological alternatives with respect to appropriate technology criteria; and a multi-factor analysis to integrate information from the preceding analytical steps. Fourth are community forums in which further participatory action and research is planned on the basis of the recommendations emerging from the tool. Through these steps, the decision-making support tool guides implementing organizations through the stages of safe water systems design and planning in a manner that centres local people in the process. The tool weaves together several theoretical and methodological strands including humanitarian engineering, post-normal science, appropriate technology, participatory development, grounded theory, engineering decision-making, and water treatment engineering. The case study application of the decision-making support tool was conducted in a marginalized peri-urban community called Mylai Balaji Nagar in Chennai, India. This indicated that a household level approach is more appropriate for the case study community and that the TATA Swach filter, alum coagulation with chlorination, or boiling, in order of decreasing suitability, may be appropriate technologies for household application in the case study community. / Degree: Doctor of Philosophy Department: School of Engineering Advisor: Hall, Kevin / International Development Research Centre (IDRC)
23

A Comparision Of Object Oriented Size Evaluation Techniques

Sirakaya, Hatice Sinem 01 January 2003 (has links) (PDF)
Popular Object Oriented size metrics and estimation methods are examined. A case study is conducted. Five of the methods (&ldquo / LOC&rdquo / , &ldquo / OOPS&rdquo / , &ldquo / Use Case Points Method&rdquo / , &ldquo / J.Kammelar&rsquo / s Sizing Approach&rdquo / and &ldquo / Mark II FP&rdquo / ) are applied to a project whose requirements are defined by means of use cases. Size and effort estimations are made and compared with the actual results of the project.
24

Evaluation and improvement of coagulant disinfectant products for humanitarian emergency relief

Borrett, Leigh A. 02 September 2020 (has links)
As climate change progresses, the number of extreme weather events are predicted to rise and generate an increase in climate related humanitarian emergencies. These emergencies result in complex displacements of populations, unsanitary conditions, and a corresponding increase in diarrheal disease risks within affected communities. Because diarrheal disease ranks as one of the major contributors to overall morbidity and mortality rates following a disaster, it is critically important that aid agencies are prepared to make informed decisions regarding the prevention of disease transmission. As water is one of the main transmission routes of diarrheal disease, providing clean and safe drinking water is acknowledged as one of the most important and effective interventions. Once we acknowledge the importance of this resource, we also acknowledge the need for quick, simple, and effective water treatment solutions. The term point-of-use (POU) water treatment defines water treatment systems and technologies that are used at the point of consumption. These systems often treat relatively small batches of water and are operated by the consumer or head of household. POU water treatment systems and safe storage techniques have been shown to improve water quality and decrease diarrheal disease incidence and are therefore an effective option in humanitarian emergencies. One type of POU water treatment product - coagulant/disinfection products (CDPs) which are also known as flocculant/disinfectants, have been increasingly used in response to humanitarian emergencies. CDPs are shown to provide microbial and aesthetic (i.e. turbidity reductions) water quality improvements and post-treatment protective free chlorine residuals (FCRs). The relative simplicity of CDPs allows quick intervention for communities with few resources plus CDPs are durable, small, and ready for quick deployment. However, limited research has been completed on the different CDPs on the market or on methods to improve them. This thesis explores CDPs and their role in emergency response through two interlinked perspectives: 1. First, in an overall review compiled as Manuscript #1 (Chapter 2), I assess the existing and current CDPs, how they perform in comparison to global water treatment guidelines, and where their limitations lie. The outcomes of this study provide a simple analysis for aid agencies to carefully select the CDPs used in emergency interventions; and 2. I take the findings from the research completed in Chapter 2 to develop a computational modelling approach to improving the residual protective capacity of the CDPs. These results are presented in Manuscript #2 (Chapter 3) . The outcomes are intended to serve two purposes: (1) to provide a baseline computational model to guide and encourage improvement and testing of these products by manufacturers; and (2) to provide an educational tool to facilitate understanding of these products and the key functions taking place during their treatment. This thesis addressed the research objective of invoking conversation surrounding effective emergency response through developing solutions to provide clean drinking water in at-risk communities during complex humanitarian emergencies. / Graduate
25

Effects of Physical Disturbances on BioSand Filters Used for Point-of-Use Water Treatment

Mahaffy, Naomi C. 04 1900 (has links)
<p>Over 750 million people, 80% of whom live in rural communities, lack access to improved water sources. Even where an improved water source is easily accessible, recontamination and/or inadequate infrastructure may make it unsafe for human consumption. A lack of safe water leads to elevated rates of waterborne diseases and can exacerbate cycles of poverty by forcing individuals to miss school and work and to travel greater distances to secure better-quality water. Households in rural and remote communities may thus choose to use point-of-use treatment as a means of gaining greater control over their water quality and the health of their families. The BioSand Filter (BSF) is one such technology: it is an intermittently-operated household-scale slow sand filter currently used in over 70 nations around the world.</p> <p>This thesis situates point-of-use water treatment, and specifically the BSF, within the context of the relationship between water and health and the continuum of technologies used for water treatment. From this foundation, it presents the methodology and results of a study carried out to inform best-practices around BSF use by: (a) examining the effects on BSF media and filtration performance of physical disturbances that may commonly occur in the field; and (b) assessing whether the biological community within BSFs promotes nitrification that could produce elevated nitrate/nitrite levels.</p> <p>Results demonstrated that disturbing the filters through moving and side impacts caused marked sand compaction and decreased flow rates for plastic (Hydraid) BSFs. Although these decreased flow rates may contribute to user frustration and disuse, they were not associated with reduced filtration performance. Nitrate and nitrite concentrations were well below WHO guidelines for all samples, but changes in nitrogen speciation suggested that nitrification was mediated by the biological community within the filters. Recommendations for practitioners and for future research are discussed in light of these findings.</p> / Master of Applied Science (MASc)
26

Springing for Safe Water: Drinking Water Source Selection in Central Appalachian Communities

Patton, Hannah Elisabeth 24 October 2019 (has links)
There are rural residents of Central Appalachia that collect their drinking water from roadside springs despite having access to in-home piped point-of-use (POU) water. Residents have cited perceptions about water availability/quality as primary motivators for collecting drinking water from roadside springs. Water from roadside springs has been found to contain total coliform and E. coli, suggesting that consumers may be at an increased risk of contracting gastrointestinal illnesses. This research effort seeks to better understand roadside spring usage in Central Appalachia, by exploring motivations influencing potable water source selection and comparing household and spring water quality to Safe Drinking Water Act recommendations. Households were recruited from communities surrounding springs in three states (Kentucky, Virginia, and West Virginia). 24 tap water samples were collected from participating households and paired with samples from six roadside springs. Samples were analyzed for fecal indicator bacteria and inorganic ions. Study participants also completed short surveys to inventory their perceptions of their household drinking water. The majority of participants did not trust their home tap water, indicating water aesthetics as primary motivators for distrust of their homer water source. Statistical comparisons indicated that 10 water quality constituents (Cd, F, NO3-, Cu, Pb, Ag, Mn, Zn, Na, and Sr) were significantly higher in tap water samples and four constituents (total coliform, U, Al, and SO2-4) were significantly higher in spring samples. These results suggest that residents might be exposed to different risks based on their drinking water source and that water quality solutions must be devised case-by-case. / Master of Science / Some rural residents of Central Appalachia collect their drinking water from roadside springs, despite having access to piped drinking water at their homes. Water collected from roadside springs can contain harmful bacteria, suggesting that people may risk exposure to illness when consuming spring water. Through a household water quality study, this research effort aims to compare roadside spring and in-home tap water quality in order to determine what contaminants are present at each source, and why residents are choosing spring water over tap water. Households were recruited from communities surrounding roadside springs in three states (Kentucky, Virginia, and West Virginia). A total of 24 tap water samples were collected from participating households, and compared with samples from six nearby roadside springs. Samples were analyzed for bacteria, metals, and nutrients. Study participants were also asked to complete short surveys to better understand their perceptions of their drinking water sources. The majority of participants did not trust their home tap water, citing aesthetic concerns as the primary reason behind their distrust. When comparing roadside spring and home samples, 10 contaminants (Cd, F, NO3-, Cu, Pb, Ag, Mn, Zn, Na, and Sr) had greater concentrations in home tap water samples and four (total coliform, U, Al, and SO2- 4) had greater concentrations in spring samples. While home water samples had higher levels of metals, roadside spring samples had higher levels of bacteria, suggesting that residents might be exposed to different risks based on water source and that water quality solutions must be developed case-by-case.
27

Occurrence of Per- and Polyfluoroalkyl Substances (PFAS) in Private Water Supplies in Southwest Virginia

Hohweiler, Kathleen A. 24 May 2023 (has links)
Per- and polyfluoroalkyl substances (PFAS) are a class of man-made contaminants of increasing human health concern due to their resistance to degradation, widespread occurrence in the environment, bioaccumulation in human and animal organ tissue, and potential negative health impacts. Drinking water is suspected to be a primary source of human PFAS exposure, so the US Environmental Protection Agency (US EPA) has set interim and final health advisories for several PFAS species that are applicable to municipal water supplies. However, private drinking water supplies may be uniquely vulnerable to PFAS contamination, as these systems are not subject to EPA regulation and often include limited treatment prior to use for drinking or cooking. The goal of this study was to determine the incidence of PFAS contamination in private drinking water supplies in two counties in Southwest Virginia (Floyd and Roanoke), and to examine the potential for reliance on citizen-science based strategies for sample collection in subsequent broader sampling efforts. Samples for inorganic ions, bacteria, and PFAS analysis were collected on separate occasions by homeowners and experts at the home drinking water point of use (POU) in 10 Roanoke and 10 Floyd County homes for comparison. Experts also collected an outside tap PFAS sample. At least one PFAS compound was detected in 76% of POU samples collected (n=60), with an average total PFAS concentration of 23.5 parts per trillion (ppt). PFOA and PFOS, which are currently included in EPA health advisories, were detected in 13% and 22% of POU samples, respectively. Of the 31 PFAS species targeted, 15 were detected in at least one sample. On average, a single POU sample contained approximately 3 PFAS, and one sample contained as many as 8 different species, indicating that exposure to PFAS in complex mixtures is worth noting. Although there were significant differences in total PFAS concentrations between expert and homeowner collected samples (Wilcoxon, alpha = 0.05), it is unclear whether this difference was due to contamination by the collector or the water usage and time of day of sampling (i.e. morning, afternoon). It is worth noting that there was no significant difference in the number of PFAS species in the samples collected by homeowners and experts. Given the considerable variation in PFAS detections between homes, future studies reliant on homeowner collection of samples appears possible given proper training and instruction to collect at the same time of day (i.e. first thing in the morning). / Master of Science / Per- and polyfluoroalkyl substances (PFAS) belong to a large family of manmade compounds that are commonly used in a variety of household and consumer products due to their unique water and stain resistant properties. PFAS compounds are not easily broken down in the environment and have been detected globally in air, soil, and water samples. In addition to their environmental detections, PFAS are slow to be removed from the body after ingestion and known to cause negative health effects in concentrations less than one part per trillion. Drinking water is considered to a main source of PFAS consumption for humans; as such, the US Environmental Protection Agency (US EPA) has set strict, but not legally binding, interim and final health advisories (HA) for four types of PFAS. However, these health advisories only apply to public water services and do not cover private drinking water systems, such as wells or springs, which are the full responsibility of the well owner. Private drinking water system users often do not treat their water before drinking which may make these systems uniquely vulnerable to PFAS contamination. This study focused on 20 total homes, 10 in Roanoke County and 10 in Floyd County to see if PFAS was present and to determine whether or not homeowners would be able to collect their own samples for PFAS analysis at home as accurately as researchers or experts with proper instructions. Homeowners and experts collected drinking water samples inside at a point of use (POU), usually at a kitchen faucet, and outside of the home, usually from a tap. PFAS were present in 76% (n=60) of POU samples, with an average combined concentration of 23.5 parts per trillion (ppt). The two most well studied PFAS, PFOA and PFOS were detected in 13% and 22% of POU samples, respectively. It was also common to detect at least 3 PFAS in a single sample. Although there were differences in total average concentrations of PFAS in samples collected by homeowners and experts, variation could be caused by several factors indicating that with proper training and instruction it is likely future studies could still rely on homeowners to collect samples for PFAS analysis.
28

Sustainable Nanomaterials Combined with Raman Spectroscopy-based Techniques to Advance Environmental Sensing

Rahman, Asifur 22 February 2023 (has links)
The propagation of contaminants in the environment continues to threaten public health and safety. Conventional analytical techniques for environmental detection require centralized facilities and intensive resources for operation. An effective implementation of a wide network of field deployable point-of-use (POU) sensors can potentially enable real-time monitoring of water quality parameters and inform decision making on public health outbreaks. The use of nanotechnology and field-deployable analytical tools can potentially advance the development of POU sensors for future field application. In this dissertation, we developed environmental sensing techniques that utilize nanocomposites made of low-cost, biocompatible, and sustainable nanomaterials combined with Raman spectroscopy. First, a technology pre-assessment was performed that included a comprehensive evaluation of cellulose-derived nanocomposites and nanobiotechnology enabled techniques for their sustainable long-term environmental application. Furthermore, to contribute to the better understanding of the potential environmental implications of nanomaterial production and application, life cycle assessment (LCA) was used to evaluate the environmental impacts of six iron precursors and seven iron oxide nanoparticle synthesis methods. Secondly, in the technology development step, gold (Au) and iron oxide (Fe3O4) nanoparticles were incorporated onto bacterial cellulose nanocrystals and nanoscale magnetite were synthesized. As proof-of-concept environmental applications, the Au@Fe3O4@BCNCs were applied for the magnetic separation and surface-enhanced Raman scattering (SERS) detection of malachite green isothiocyanate (MGITC), and nanoscale magnetite were applied for phosphate (PO43-) removal and recovery from synthetic urine matrices. Finally, in the technological application step, three environmental sensing applications are presented that use nanomaterial-based sensor platforms and/or Raman spectroscopic techniques. The first application involved using Lectin-modified BCNCs coupled SERS and machine learning for discrimination of bacterial strains. The second application presents a simple Raman-stable isotope labeling approach for the study of viral infection of bacteria. The third application involved use of SERS pH nanoprobes for measuring pH in droplets of complex matrices (e.g., DMEM cell culture media, human saliva). / Doctor of Philosophy / The current generation of analytical tools for environmental detection rely upon centralized facilities and intensive resources for operation. The combination of nanotechnology and field deployable analytical tools can aid in the development of point-of-use (POU) sensors for field monitoring of environmental contaminants. In this dissertation, we combined low-cost, biocompatible, and sustainable nanomaterials with Raman spectroscopy-based techniques to develop potentially field-deployable environmental sensing techniques. First, a technology pre-assessment was performed which involved a comprehensive evaluation of cellulose-derived nanocomposites and nanobiotechnology enabled techniques for their sustainable long-term environmental application. Furthermore, life cycle assessment (LCA) was used to evaluate the environmental impacts of iron oxide nanoparticle synthesis methods to better understand environmental impacts of nanoparticle production. Secondly, in the technology development step, we developed the nanocomposites: Au and Fe3O4 nanoparticles incorporated bacterial cellulose nanocrystals and nanoscale magnetite. As proof-of-concept environmental applications, the Au@Fe3O4@BCNCs were used for the detection of malachite green isothiocyanate (MGITC), and the nanoscale magnetite were used for phosphate (PO43-) removal and recovery from synthetic urine. Finally, in the technological application step, (1) selective detection of bacteria was performed using lectin-modified BCNCs as SERS biosensors coupled with SERS and machine learning. (2) Viral infection of bacteria was evaluated using Raman spectroscopy and Deuterium isotope labeling, and (3) pH in micro-droplets of DMEM cell culture media and human saliva were observed using SERS pH nanoprobes.
29

Clean water for all: The demographics of urban and rural safe drinking water challenges in Virginia, USA and San Rafael Las Flores, Guatemala

Marcillo, Cristina Elizabeth 14 April 2020 (has links)
The United Nations established Sustainable Development Goal 6, universal access to safely managed drinking water and sanitation service, as a global goal for 2030. In rural areas, access lags significantly and progress is rarely examined concurrently between developed and developing nations. Therefore, this dissertation focuses on rural water system challenges in a developed nation, the US, and a developing nation, Guatemala. In the US, approximately 250 million Americans receive drinking water from community water systems (CWSs), theoretically safeguarded by the Safe Drinking Water Act (SDWA). There is mounting evidence that racial, ethnic, and socioeconomic disparities persist in US drinking water access and quality, but studies are limited by the exclusion of very small CWSs and a large geographic unit of analysis. A novel geospatial methodology was created to delineate system service areas at the zip code scale in Virginia and assess the influence of demographic characteristics on compliance with the SDWA from 2006 to 2016. Results reveal that monitoring and reporting violations are concentrated in private, rural systems that serve fewer than 500 people, while health-based violations were more likely in non-white communities, specifically those with higher proportions of Black, Native Hawaiian, and other Pacific Islanders. This study was completed in parallel with a household sampling campaign in rural San Rafael Las Flores, Guatemala. In Guatemala, no public access to water system compliance or quality information currently exists. With growing investment in mining industries and recognized naturally occurring arsenic in volcanic geology, citizens are eager for drinking water information. Survey results highlighted dissatisfaction with and distrust in most tap water sources. Consequently, residents regularly buy bottled water or collect water from untreated natural springs. Water quality results indicated that tap water from the central drinking water treatment plant contained higher levels of arsenic and other contaminants, when compared to most other sources. Though the settings are quite different, parallel investigation of rural drinking water system challenges in the US and Guatemala reveal common challenges and lessons. Moving forward, all nations would benefit from standard monitoring of drinking water access, quality, and compliance that allowed for intersectional investigations of environmental health inequities. / Doctor of Philosophy / In 2015, the United Nations established Sustainable Development Goal 6 which establishes safely managed drinking water and sanitation service for all as a global goal. Access to safe drinking water lags significantly in rural areas and can be complicated by intersecting social determinants of health (e.g. race, wealth). Rarely is progress in developed and developing nations examined concurrently, hindering an understanding of commonalities and an exchange of lessons. To this end, my dissertation focuses on rural water system challenges in a developed nation, the United States, and a developing nation, Guatemala. In the US, more than 250 million Americans receive in-home drinking water from one of 53,000 community water systems, with quality theoretically protected by the Safe Drinking Water Act (SDWA). Recent failures, such as the lead crisis in Flint, MI, have cast doubt on the equity and reliability of these utilities, especially in underserved areas. How can we ensure that all US communities receive equal protections under the Safe Drinking Water Act? Using publicly available data and geography, this work estimated service areas to determine whether SDWA violations related to surrounding community socio-demographics and/or system design. Results reveal that monitoring and reporting violations are significantly concentrated in private, rural systems that serve fewer than 500 people, while health-based violations were more likely in non-white communities, specifically those with higher proportions of Black, Native Hawaiian, and other Pacific Islanders. These findings illustrate potential issues of environmental justice within VA and advocate for future research to investigate potential structural causes. This work was completed in tandem with a household sampling campaign in rural San Rafael Las Flores, Guatemala. In Guatemala, there is currently no public access to water system compliance or quality information. With recognized naturally occurring carcinogenic elements in Guatemala's volcanic geology, such as arsenic, and heightened investment in extractive industries such as mining, that can compromise source water quality, citizens are eager for drinking water quality data. Survey results documented widespread dissatisfaction with and distrust in tap water quality. As a consequence, residents regularly buy bottled water or collect water from natural springs. Water quality results showed that tap water sourced from the central drinking water treatment plant contained significantly higher levels of arsenic and other contaminants when compared to most other tap sources. Community participation in long-term water monitoring and infrastructure decisions may help build trust in water sources. Though the regulatory, economic, and cultural settings are quite different, parallel investigation of rural drinking water system challenges in the US and Guatemala reveal common challenges and lessons. Moving forward, high, middle, and low-income nations all benefit from standard monitoring of drinking water access, quality, and compliance that allows for intersectional investigations of environmental health inequities.
30

Innovative techniques for the quantification of waterborne microbial risks in field studies

Zimmer, Camille 30 August 2019 (has links)
In low-resource contexts, household-level point-of-use water treatment (POUWT) techniques are the final, and sometimes only, barrier against waterborne illnesses, and in these and other water-related applications, health risks can be quantified using one of two methods. Firstly, Escherichia coli (or other indicator organism) counts can be used to monitor water and determine adherence to a health-based limit (i.e. compliance monitoring). Secondly, E. coli can be used to conduct a quantitative microbial risk assessment (QMRA), indicating the level of protection conferred by a given POUWT device by spiking test water with E. coli to ascertain a reduction efficacy relative to that target organism, a process referred to as challenge testing, which is typically carried out in a laboratory context. Although both methods are well established, both have scope for improvement for effective field application in low-resource contexts. Regarding compliance monitoring, I assessed the performance of a new low-cost field kit for E. coli enumeration, which was designed by others. I also assessed the feasibility of re-using some disposable materials, in terms of sterility and mechanical wear. The use of the new low-cost field kit was successful during the fieldwork campaign; however, re-using disposable materials introduced a relatively high occurrence of false positive results during E. coli enumeration. Use of the new low-cost field kit can reduce financial barriers, thus enabling greater water quality testing coverage. Regarding challenge testing, the aim of this study was to adapt current protocols to assess the household performance (as opposed to laboratory performance) of POUWT techniques. I developed a conceptual framework to conduct Field Challenge Tests (FCT’s) on POUWT techniques, using a probiotic health supplement containing E. coli as the challenge organism. I successfully carried out a FCT in Malawi with limited resources, verifying FCT viability. Applications of such FCT’s include quality control practices for manufactured devices, guiding QMRA and recommendations by public health organizations regarding POU device selection, and assessing the impact of user training programmes regarding POUWT techniques. / Graduate

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