MESHWR / Department of Hydrology and Water Resources / Water borne diseases due to inadequate and unsafe drinking water is a global challenge that has led to a significant number of deaths and illnesses reported annually. These diseases are prevalent in less-developed countries, especially in rural areas where there is shortage of basic infrastructure and inadequate funds for piped water systems in individual households. Community members are forced to resort to collecting water from communal water points and later storing the water in containers for daily use. Recontamination of microbiologically safe drinking water during and after collection from the water source has been recognised as a problem; hence treating water at household level is one way to provide potable water for affected communities. The microbiological quality of household water may be improved by using point-of-use treatment technologies such as chemical disinfection, solar disinfection and ceramic water filters. Some of these technologies are expensive, less effective and difficult to implement in rural communities. This research thus focused on ceramic water filters and finding an appropriate method for silver application so as to produce filters that are effective in both the provision of clean drinking water and the release of silver levels that are safe for human consumption. An assessment of the efficiency of ceramic water filters made with silver nitrate as point-of -use water treatment device in Dertig Village, North West Province, South Africa was carried out. During production of filters made with silver nitrate, the filters undergo firing in an electric kiln and ionic silver is reduced to metallic nanopatches dispersed throughout the porous ceramic media. Both filters made with silver nitrate and conventional silver nanoparticles impregnated ceramic water filters were manufactured at the PureMadi Dertig Ceramic Filter Facility, South Africa. Resulting filters were evaluated and quantified for total coliform and E. coli removal as well as silver concentration in the effluent. Ceramic water filters made with silver nitrate had a high removal efficiency for total coliforms (94.7%) and E. coli (99.3%). A comparison of the performance of filters made with silver nitrate and silver nanoparticles in the provision of potable water was carried out and results showed that the different filters had similar levels of total coliform and E. coli removal, although the silver nitrate filters produced the highest average removal of 97.23% while silver nanoparticles filters produced the lowest average removal of 85.43%. Reasonable silver levels were obtained in effluent from all filters. Average effluent silver levels were 0.07±0.04mg/L, 0.6±1.10 mg/L and 0.8±1.0mg/L for 1 g, 2 g and silver nanoparticle filters, respectively (below the EPA and WHO standard of 100 mg/L). Because silver nitrate filters resulted in the lowest effluent silver concentrations, this could potentially increase the effective life span of the filter. A cost analysis of the process proved that it was cheaper to produce ceramic water filters using silver nitrate as the chemical can be purchased locally and also eliminates labour related costs. Thus, filters made using silver nitrate could potentially improve performance, reduce production costs, and increase safety of production for workers. The results obtained from this study will be applied to improve the ceramic filtration technology as point-of-use water treatment device in an effort to reduce health problems associated with microbial contamination of water stored at household level. / NRF

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.

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.

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.