Tracking SARS-CoV-2 RNA through the Wastewater Treatment Process

Abstract

Municipal sewage carries degraded and intact viral particles and RNA (ribonucleic acid) of SARS-CoV-2 (severe acute respiratory coronavirus 2), shed by COVID-19 (coronavirus disease 2019) patients, to sewage and eventually to wastewater treatment plants. Proper wastewater treatment can prevent uncontrolled discharges of the virus into the environment. However, the role of different wastewater treatment stages in reducing viral RNA concentrations is, thus far, unknown. Here, we quantified SARS-CoV-2 RNA in raw sewage and during the main stages of the activated sludge process from two wastewater treatment plants in Israel, on three different days during the 2020 COVID-19 outbreak. To reduce the detection limit, samples were concentrated prior to quantification by real-time polymerase chain reaction by a factor of 2–43 using ultrafiltration. On average, ∼1 log RNA removal was attained by each of the primary and secondary treatment steps; however, >100 copies of SARS-CoV-2 RNA/mL remained in the secondary effluents. Following chlorination, SARS-CoV-2 RNA was detected only once, likely due to an insufficient chlorine dose. Our results emphasize the capabilities and limitations of the conventional wastewater treatment process in reducing the SARS-CoV-2 RNA concentration and present preliminary evidence for the importance of tertiary treatment and chlorination in reducing dissemination of the virus to the environment.

Sources, fates and treatment strategies of typical viruses in urban sewage collection/treatment systems: A review

“…Similarly, the resistance of typical viruses to chlorine dioxide declined as follows: HRoV > coxsackie virus > echovirus > PV > f2 phages > monkey RoV [15] , [163] , [164] , [165] . Compared to chlorine dioxide, chlorine exhibited a much higher inactivation efficiency for SARS-CoV and SARS-CoV-2, which could be proven by the observation of complete inactivation of SARS-CoV by 20 mg·L −1 chlorine after a 1 min reaction [58] , [166] . Inactivation by chlorine dioxide for virus removal is temperature- and pH-dependent, and the virucidal efficiency of EV 71 was higher at pH 8.2 than at pH 5.6 and pH 7.2.…”

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Fig. 2 Mechanism and log removal efficiency of different viruses during different WWTP units operation [69] , [73] , [104] , [108] , [121] , [122] , [123] , [124] , [125] , [126] , [127] , [128] , [129] . (SARS-CoV-2, severe acute respiratory syndrome coronavirus2; PyVs, polyomavirus; RoV, rotavirus; NoV GII, norovirus GII; NoV GI, norovirus GI; EV, enterovirus; AdV, adenovirus; HTtV, human torque teno virus; HPyV, Human polyomavirus; PLVs, primate lentivirus; AV, astrovirus; SaV, sapovirus).

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Metagenomics of Wastewater Influent from Wastewater Treatment Facilities across Ontario in the Era of Emerging SARS-CoV-2 Variants of Concern

“…The emergence and global spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (genus Betacoronavirus , family Coronaviridae ) variants of concern (VOCs) pose a significant threat to global health ( 1 , 2 ). SARS-CoV-2 is shed in human fecal matter and less so in urine by infected individuals, and its detection in wastewater triggered global interest in tracking the dissemination of its VOCs ( 3 , 4 ). The province of Ontario and other jurisdictions have adopted genomic surveillance of wastewater for monitoring known and emerging SARS-CoV-2 VOCs in the community ( 5 – 12 ).…”

Elucidating the role of environmental management of forests, air quality, solid waste and wastewater on the dissemination of SARS-CoV-2

“…Chlorine disinfection has been solely recommended for environmental disinfection purposes and the consideration of residual chlorine is recommended ( Abu Ali et al, 2021 ; Xiling et al, 2021 ). For example, Achak et al (2020) and Zhang et al (2020a) addressed China's hospital wastewater guidelines for urgent disinfection during the COVID-19 pandemic which requires addition of a minimum of 6.5 mg/L free chlorine for 1.5 hours in wastewater, irrespective of pH levels.…”