Electronic Thesis and Dissertation Repository

Thesis Format

Alternative Format

Degree

Master of Science

Program

Microbiology and Immunology

Supervisor

Arts, Eric J.

Abstract

The COVID-19 pandemic has emphasized the importance of wastewater surveillance to monitor the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Increased surveillance requires attention to municipal workers who collect and handle samples at treatment facilities. While SARS-CoV-2 is primarily transmitted through respiratory droplets, evidence suggests virus can be transmitted via fecal-oral route and contaminated environmental samples, including municipal wastewater. This project investigated SARS-CoV-2 infectivity in wastewater and assessed potential risks to municipal workers and all those in contact with wastewater. Vero E6 infectivity assays determined inactivation kinetics of SARS-CoV-2 in time and temperature-based assays, aerosolization assays, and UV disinfection studies. Stability in infectivity was observed in 23, 15 and 4oC spiked samples with longer viral survival observed at colder temperatures. SARS-CoV-2 in wastewater aerosols was infectious directly to Vero E6 cells and also maintained infectivity in aerosolized droplets settling on various materials such as plastic and stainless-steel. The log reduction kinetics were also defined using collimated-beam UV irradiations to determine the optimal UV dosage for viral inactivation. Understanding SARS-CoV-2 infectivity in the wastewater treatment process is essential to inform public health by providing crucial information on risks associated with handling wastewater to prevent community spread.

Summary for Lay Audience

The coronavirus disease 19 (COVID-19) pandemic has brought to light the importance of monitoring wastewater for the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Wastewater surveillance is an effective way to track the virus in communities since it can detect traces of the virus in fecal matter even before individuals show symptoms. This can help public health officials identify outbreaks and implement measures to prevent further spread. However, this increased surveillance comes with its own set of challenges. Municipal workers who collect and handle samples at treatment facilities are at risk of exposure to the virus. While the primary mode of transmission of the virus is through respiratory droplets, evidence suggests that the virus can also be transmitted through the fecal-oral route and contaminated environmental samples, including wastewater.

To better understand the risks associated with handling wastewater, this project was conducted to investigate the infectivity of SARS-CoV-2 in wastewater. The project used Vero E6 cell infectivity assays to determine the inactivation kinetics of the virus under different conditions such as time and temperature-based studies, UV disinfection, and aerosolization assays. Results from these assays found that there were differences in the inactivation of the virus in samples spiked with SARS-CoV-2 held at different temperatures including 23, 15, and 4oC. The project found that infectious virus can be carried in wastewater aerosols in material experiments with plastic and stainless-steel, as well as direct sprays onto Vero E6 cells which means that workers who handle wastewater need to take extra precautions at the treatment facilities to prevent exposure. The log reduction kinetics were also defined using collimated-beam UV irradiations, where the amount of UV exposure required to inactivate the virus was identified.

Understanding SARS-CoV-2 infectivity in the wastewater treatment process is crucial to inform public health and provide information on the risks associated with handling wastewater. This information can help prevent community spread and ensure the safety of workers who are on the front lines of handling wastewater. It is essential to continue research in this area to further develop guidelines and protocols to minimize the risks associated with handling wastewater.

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