There are many ways to test urban sewage for signs of the virus that causes COVID-19, but Houston scientists have determined that theirs are the best ever.
A study led by Lauren Stadler, an environmental engineer at Rice University’s Brown Institute of Technology, with the support of the Houston City Health Department and Baylor College of Medicine, concentrated samples and nationwide to find six wastewater viruses. A Houston plant comparing the five processes used in the laboratory.
A process called “electronegativity with bead beats” used by Rice and today’s Baylor has proven to be the most sensitive and cost-effective for signs of the virus.
The study is published in the Elsevier Journal Water research..
Studies have shown that there are no standard tests, but all processes, including electronegative filtration with elution, ultrafiltration, precipitation, and direct extraction, are somewhat effective.
“The virus is so diluted in wastewater that we need a way to concentrate it,” Stadler said in explaining the rice process. “First, salt is added to the wastewater sample to promote the adsorption of the virus on the electronegative filter. After filtration, the filter is physically tapped with glass beads to release the virus to the lysate. This process causes the virus to release. It can be disrupted, but it only detects and quantifies a small portion of the RNA genome. “
Founded in the spring of 2020, the Houston Union was at the forefront of a national effort to find the SARS-CoV-2 virus in wastewater. The technology quickly proved predictable for COVID-19 outbreaks, allowing health authorities to enhance testing as needed.
When we started the test, Baylor was using a different method. This gave me the opportunity to make many direct comparisons as to which method to use. Therefore, other groups around the world wanted a more comprehensive assessment of some of the commonly used methods for concentrating SARS-CoV-2 in wastewater. “
Lauren Stadler, Environmental Engineer, Brown Institute of Technology, Rice University
“There is more than one right way, but I wanted to consider other options,” she said. “Our recommendations and final method choices were based on finding a balance between sensitivity, throughput and cost.
“The first method we chose turned out to be the lowest detection limit, while at the same time relatively high throughput and cost-effectiveness,” says Stadler. “As a result, Baylor switched to the same enrichment method, which gave us confidence that we were really producing the best possible data for the city.”
Researchers in Houston hope that this study will guide municipalities around the world that have or are considering their own wastewater testing labs.
“Many major cities have already done this, and now there are state-wide programs in Michigan, Wisconsin, North Carolina, and several other states,” Stadler said. She said the Houston Institute is already looking for COVID mutations. “We are doing research on sequencing wastewater samples so that we can detect highly contagious mutants circulating in the community,” says Stadler.
Even the research done is a bonus given the workload of Stadler’s Rice Labs and the counterparts of Baylor and Houston Health Department. Since its launch in mid-2020, the lab has analyzed hundreds of samples per week from 39 wastewater treatment facilities in the city. Since then, Houston has added test points to dozens of nursing homes, schools and other important locations.
“The city plans to increase the number of stations to get zip code level information, and we’re working with them to analyze that data,” Stadler said. “One day, it could be a tool to look for the virus panel as well.”
Laterer, ZW, et al.. (2021) Assessment of recovery, cost, and throughput of various enrichment methods for SARS-CoV-2 wastewater-based epidemiology. Water research.. doi.org/10.1016/j.watres.2021.117043..