Issue 5, 2023

Wastewater-based surveillance of COVID-19 and removal of SARS-CoV-2 RNA across a major wastewater treatment plant in San Antonio, Texas

Abstract

Wastewater-based epidemiology (WBE) targeting SARS-CoV-2 RNA detection in municipal wastewater is considered a valuable tool for COVID-19 surveillance in a community. However, the persistence and removal of SARS-CoV-2 RNA in wastewater treatment plants (WWTPs) have not been well investigated. This study is aimed at detecting SARS-CoV-2 RNA in wastewater to correlate viral concentrations with clinical COVID-19 cases in the sewershed and determine whether the SARS-CoV-2 genetic material is detectable after treatment. Raw influent, primary effluent (after primary clarification), secondary effluent (after activated sludge treatment), and final effluent (after chlorination) samples were collected two times a week from the largest WWTP in San Antonio (Texas) during April to November 2021 and analyzed for SARS-CoV-2 RNA (N1 and N2 genes) concentrations using the reverse transcription droplet digital polymerase chain reaction (RT-ddPCR). SARS-CoV-2 RNA was detected in 98.5% (n = 34 weeks) of the raw influent samples and anticipated the trends of the COVID-19 outbreak. Furthermore, a higher correlation between viral concentrations and COVID-19 cases was observed for two days a week sampling frequency (ρ = 0.75, p <0.001) than one day per week (ρ = 0.60, p <0.001). Despite the high SARS-CoV-2 RNA concentrations in raw sewage, a significant amount of viral RNA was removed at primary and secondary clarifiers (removal efficiencies were 54% and 94%, respectively) and was undetectable in final effluents. These results demonstrate the performance of the WWTP in reducing the SARS-CoV-2 RNA concentration and further highlight the role of tertiary treatment and chlorination in eliminating SARS-CoV-2 RNA in receiving waters.

Graphical abstract: Wastewater-based surveillance of COVID-19 and removal of SARS-CoV-2 RNA across a major wastewater treatment plant in San Antonio, Texas

Supplementary files

Article information

Article type
Paper
Submitted
23 jan 2023
Accepted
12 mrt 2023
First published
15 mrt 2023
This article is Open Access
Creative Commons BY-NC license

Environ. Sci.: Adv., 2023,2, 709-720

Wastewater-based surveillance of COVID-19 and removal of SARS-CoV-2 RNA across a major wastewater treatment plant in San Antonio, Texas

H. Al-Duroobi, K. K. Vadde, D. C. Phan, S. V. Moghadam, A. Jafarzadeh, A. Matta, M. Giacomoni and V. Kapoor, Environ. Sci.: Adv., 2023, 2, 709 DOI: 10.1039/D3VA00015J

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