A combined sewer drain drain. Credit: US Environmental Protection Agency.
Can antibiotic-resistant bacteria escape from sewers into waterways and cause an outbreak of disease?
A new study by Rutgers, published in the magazine. Environmental science: water research and technologyHe examined microbial-laden “biofilms” that cling to sewer walls, and even built a simulated sewer to study the germs that survive inside.
They found that these biofilms often contain harmful antibiotic-resistant bacteria and can withstand standard treatment to disinfect sewers. Cleaning with bleach can reduce the density of biofilms, but not completely eliminate them, which can expose wastewater treatment workers and the public to health risks.
Still, disinfecting a sewer line may be a good idea before performing sewer maintenance, especially after events like a disease outbreak or a bioterrorism incident that could expose sewer lines to high-risk microbes. Fortunately, with respect to SARS-CoV-2, the coronavirus that causes COVID-19, water and sewage are not expected to be major transmission routes.
Typically, what is flushed down a toilet goes to a sewage treatment plant. But rain can cause untreated waste overflows in bays, rivers, streams, and other waterways. The researchers say a possible worst-case scenario would be an outbreak of infectious disease after a sewer overflow that releases sewage, sewage solids and biofilms to surface water.
“Given the current interest in wastewater-based epidemiology to monitor the coronavirus, our study highlights the need to consider sewer processes and the best way to combat pathogens,” said lead author Nicole Fahrenfeld, associate professor in the Department of Civil and Environmental Engineering at Rutgers University-New Brunswick School of Engineering. “We will work to repeat part of our experiments to understand how long the coronavirus can remain in sewers and whether that will affect its monitoring in the wastewater.”
The researchers found that sewer pipe materials (concrete or PVC plastic) did not affect biofilm formation, but did play a role in the effectiveness of the bleach to disinfect them. Bleach is better for removing biofilms from PVC than concrete, probably because PVC is smoother.
The lead author is William R. Morales Medina, a Rutgers PhD student. Alessia Eramo, who earned a doctorate from Rutgers, and Melissa Tu, an undergraduate student at Rutgers, contributed to the study.
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William R. Morales Medina et al., Sewer microbiome, microbiome and antibiotic resistance genes depending on the pipe material, source of microbes and disinfection: field and laboratory studies, Environmental science: water research and technology (2020). DOI: 10.1039 / D0EW00265H
Provided by Rutgers University
Citation: Harmful microbes found on the walls of sewer pipes (2020, July 6) recovered on July 6, 2020 from https://phys.org/news/2020-07-microbes-sewer-pipe-walls.html
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