A snapshot of SARS‐CoV‐2 viral RNA throughout wastewater treatment plants in Arkansas

Abstract

The severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) can spread the viral RNA in wastewater by the feces of those experience COVID‐19 symptoms. While wastewater monitoring of SARS‐CoV‐2 in the raw sewage has been confirmed as an effective tool to predict COVID‐19 infection, the goal of this study is to assess the presence of SARS‐CoV‐2 viral RNA throughout various wastewater treatment processes. Wastewater samples were collected from wastewater treatment plants (WWTPs) in the state of Arkansas from August 2020 to June 2021 and measured for the relative concentration of SARS‐CoV‐2 viral RNA using RT‐qPCR. The gene concentrations in the raw wastewater measured in this study were similar to other published studies, targeting the N1 and N2 genes of the virus. The viral RNA concentration was measured after each wastewater treatment step within WWTPs, including primary sedimentation, activated sludge, filtration and disinfection. Results show the most viral RNA removal occurred in the secondary treatment (activated sludge). The viral RNA was only occasionally detected after disinfection (chlorination or UV disinfection). Overall, WWTPs can remove the SARS‐CoV‐2 viral RNA at an average of 98.7%, while complete removal was achieved on 82% of the sampling days. Further investigation is required to ensure complete viral RNA removal from wastewater such as improving existing treatment process or supplementing with additional treatment steps.Practitioner Points The viral RNA of SARS‐CoV‐2 was detected in Arkansas wastewater treatment plants. SARS‐CoV‐2 was rarely detected in treated effluent from wastewater treatment plants. Activated sludge was effective removing SARS‐CoV‐2 viral RNA from wastewater. This study was limited by the direct RNA extraction from wastewater, which lowered the sensitivity of detection.