Wastewater may yield clues to COVID-19 infection rates

A lab technician pours a sample of wastewater at the Metro Plant into a small bottle for shipment.Metropolitan Council Environmental Services (MCES) is participating in three research studies to determine if the amount of SARS-CoV-2 genetic material in wastewater can be reliably measured and related to the prevalence of COVID-19 cases among residents in the plant’s service area.

Current research suggests that people may start shedding the virus in their feces up to a week before symptoms appear. By monitoring wastewater, scientists may be able to detect when infection rates are starting to rise in the population before clinical testing shows the trend.  The SARS-CoV-2 virus is inactive and noninfectious in the wastewater system and poses no risk to the environment.

Prior research has successfully shown wastewater can be used to measure viruses that cause hepatitis and other diseases, and to detect levels of drug use in populations.

Methods

Automatic sampling equipment collects a small amount of wastewater multiple times per day and consolidates it into a 2.5-gallon container. Representative samples are taken from this mixture after a 24-hour period.

All three studies are using the same Reverse Transcription-Quantitative Polymerase Chain Reaction (qPCR) method to measure the amount of viral genetic material, expressed in copies per liter.

Biobot study in Cambridge, MA

MCES sent its first weekly wastewater sample to Biobot, based in Cambridge, Massachusetts, on April 21, and plans to continue through the end of August. Range of observed data so far is 62,000 to 430,000 copies/L. Not enough data yet to draw any conclusions. Total estimated cost to MCES: $12,840.

University of Minnesota Medical School, Duluth campus

Samples taken the same day as the Biobot samples are sent every other week to a UMD research lab. Study includes 22 wastewater treatment plants across the state. Project will continue at least through December. Cost to MCES: Shipping only.

Working with the U of M Genomics Center

MCES staff are also making measurements of SARS-CoV-2 of their own, with assistance from the University of Minnesota Genomics Center in Minneapolis. The viral genetic material is being measured in samples of both wastewater as it comes into the plant and of gravity-thickened sludge, material that settles out during the initial stages of wastewater treatment.

Balogh said this in-house project should be a long-term, cost-effective, and more definitive alternative to the other projects.

“Our goal is to be producing high-quality, defensible data by later this fall,” Balogh said. “If we have a way to anticipate infection trends, we may be able to help save lives.”