Novel Approaches to Monitor Virus Fate Through Water Treatment Processes
Creators: name: Rockey, Nicole
Publisher: name: My University
Year: 2021
Subjects: subject: virus inactivation
subject: water reuse
subject: virus monitoring
subject: UV disinfection
subject: flow virometry
subject: human norovirus
subject: Civil and Environmental Engineering
subject: Engineering

description: As population growth, climate change, and urbanization strain drinking water sources, the increasingly common use of diverse and impacted water supplies necessitates a better understanding of contaminant fate in this setting. Among the human health hazards found in water supplies, viral pathogens are of principal concern, because they can be present in elevated concentrations, are highly infectious, and are difficult to remove due to their small size. Effective viral pathogen removal is of particular importance in direct potable water reuse, in which wastewater is transformed into drinking water. A multibarrier approach to treatment is traditionally used for contaminant removal, where different treatment processes are placed in series and cumulatively reduce virus concentrations to levels that pose no significant public health risk. However, the persistence of several important waterborne viruses (e.g., human norovirus) through treatment processes is not well characterized due to difficulties in virus culturability. This raises questions about whether proposed reuse treatment schemes are sufficient to protect human health. In addition, monitoring strategies used to ensure treatment performance in real-time are not sufficiently sensitive to validate virus reductions, likely resulting in the design of overengineered treatment schemes for virus removal. This dissertation sheds light on alternative molecular and predictive modeling approaches for estimating virus fate through disinfection when traditional methods are not feasible and evaluates flow virometry as a novel approach to accurately validate virus reductions through treatment in real-time. Results demonstrate that alternative methods to accurately determine virus susceptibility to UV254 disinfection treatments can be applied effectively when culture-based approaches are not possible. Specifically, the UV254 sensitivity of human norovirus was established with these alternative approaches and confirmed through use of a novel culture system. The findings show that commonly used approaches to estimate infectious human norovirus levels overestimate norovirus survival through UV254 disinfection. Further, flow virometry, a high-throughput method for detecting and enumerating virus particles, was explored as a sensitive method to ensure virus reductions through treatment in real-time. Work revealed that flow virometry could effectively detect large dsDNA virus populations, while smaller RNA and DNA viruses were not reliably measured. Proof-of-concept experiments evaluating virus removal through ultrafiltration indicated that while flow virometry could detect particles in the same size range as viruses, little improvement over currently used monitoring approaches was observed due to limitations in the detection capabilities of current flow cytometers. Taken together, this dissertation research improves our understanding of human norovirus fate through treatment and provides novel methods that can be applied to monitor virus behavior through treatment. Ultimately, this research aids in the development of a regulatory framework that will make direct potable reuse more feasible, economical, and environmentally sustainable while still guaranteeing public health protection.