Many of us don't give much thought to our wastewater after we flush the toilet, let alone contemplate what it could teach us about mitigating the spread of infectious viruses and helping maintain public health. But this is the exact question Caitlyn Butler and her research team have been investigating since the spring of 2020, specifically around SARS-CoV-2 (the virus that causes COVID-19).
Butler, an associate professor in civil and environmental engineering, has spent the last fifteen months running a research team that monitors the presence of SARS-CoV-2 in the wastewater associated with the UMass Amherst campus. And she isn't alone. As of January 2021, over 210 colleges and universities across the globe have COVID-19 wastewater monitoring in place.
Butler began the project using seed grants from the Institute for Applied Life Sciences (IALS) to establish a protocol to accurately assess the presence of SARS-CoV-2 in the wastewater concentration. The work then caught the eye of the University's COVID Response Team. "We were seeing strong correlations between infected populations and the concentration of SARS-CoV-2 in the wastewater,” Butler says. "So, the university was interested in whether we could scale this up to support them."
Wastewater-based epidemiology is not a new concept and has been used historically to monitor outbreaks of infectious diseases such as polio. Butler's team currently collects samples from more than 35 catchment sites three times a week using a composite sample strategy that represents a 24-hour window within the sewer.
The samples are then taken to an on-campus laboratory for testing, and Butler reports the results to the University's COVID Response Team.
While some colleges and universities have struggled with collecting wastewater samples isolated from nearby towns or other populations, UMass is an ideal setup for this research, and not by accident. When wastewater treatment plants were first being investigated as a concept in the early 1970s, a UMass pilot plant was built immediately adjacent to the Town of Amherst's wastewater treatment plant. The plant served as a facility where researchers could run innovative research that eventually led to the implementation of plants across the country. The facility is equipped with state-of-the-art and, in some cases, "one-of-a-kind" facilities for bench-scale testing and analysis of chemical and microbial contaminants.
While UMass Amherst has a robust setup, Butler points out that wastewater monitoring is not without its complications and implications. Factors such as the flow of the wastewater, the population size being sampled, and the type of sewer infrastructure are all variables that can affect results and increase the cost of the monitoring. Butler's team hopes to use their own experience to discover new methods to improve the recovery of the virus from the wastewater matrix and help determine a framework for wastewater surveillance that others can use when deciding to implement wastewater monitoring.
Butler also points out that despite the anonymity of the data they gather, there are still important privacy concerns and ethical implications to wastewater testing that can't go overlooked. "You can't design in isolation. Whatever you design will have benefits and consequences, and it's imperative to think through what those are and what that means. I've heard engineers have these conversations around wastewater with each other and some public health officials also, but I think engaging more stakeholders is an important part of the process that shouldn't be overlooked."
Beyond leading the wastewater monitoring team, Butler also co-authored "Wastewater Surveillance for SARS-CoV-2 on College Campuses: Initial Efforts, Lessons Learned, and Research Needs" in the International Journal of Environmental Research and Public Health. The article compiled data from 25 colleges and universities implementing some version of wastewater monitoring to explore the challenges and lessons learned from the work.
Butler is currently completing a Fulbright at the University of Sheffield in England, researching how biofilms grow in the water distribution systems there. She will return to UMass Amherst in December and doesn't yet know when the wastewater monitoring at UMass Amherst will end.
"We currently have a really high rate of vaccination, but there are still breakthrough cases. As we get more confident in the new normal, I could envision rolling this back to some monitoring of a centralized location so that it's just a pulse that says everything's good. And if there are spikes, that could be our first signal that, okay, now we need to pay attention again," Butler says.