Title:

The Fate of SARS-CoV-2 Viral RNA in Coastal New England Wastewater Treatment Plants

Municipal sewage carries SARS-CoV-2 viruses shed in the human stool by infected individuals to wastewater treatment plants (WWTPs). It is well established that increasing prevalence of COVID-19 in a community increases the viral load in its WWTPs. Despite the fact that wastewater treatment plants serve a critical role in protecting downstream human and environmental health through removal or inactivation of the virus, little is known about the fate of the virus along the treatment train. To assess the efficacy of differing WWTP size and treatment processes (Figure 1) in viral RNA removal we quantified two SARS-CoV-2 nucleocapsid (N) biomarkers (N1 and N2) in both liquid and solids phases for multiple treatment train locations from seven coastal New England WWTPs. SARS-CoV-2 biomarkers were commonly detected in the influent, primary treated, and sludge samples (returned activated sludge, waste activated sludge, and digested sludge), and rarely detected after secondary treatment or disinfection. Solid phase biomarker concentrations were generally 400 to 4000 fold higher than those quantified from the liquid phase. Sludges had overall the highest concentrations, suggesting viral biomarkers accumulate or adsorb to solids during treatment. Secondary treatment and clarification removed the largest portion of viral RNA. Our results indicate that a variety of treatment train designs are efficient at achieving high removal of SARS CoV-2 RNA; therefore, viral RNA fragments cannot be detected in the secondary and treated effluent. This study demonstrates the important role municipal wastewater treatment facilities serve in reducing the discharge of SARS-CoV-2 viral fragments to the environment and highlights the need to better understand the fate of this virus in wastewater solids.

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