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Review
. 2020 Nov 15:743:140444.
doi: 10.1016/j.scitotenv.2020.140444. Epub 2020 Jun 24.

SARS-CoV-2 from faeces to wastewater treatment: What do we know? A review

Paola Foladori  1 , Francesca Cutrupi  2 , Nicola Segata  3 , Serena Manara  3 , Federica Pinto  3 , Francesca Malpei  4 , Laura Bruni  5 , Giuseppina La Rosa  6
Affiliations
Review

SARS-CoV-2 from faeces to wastewater treatment: What do we know? A review

Paola Foladori et al. Sci Total Environ. .

Abstract

SARS-CoV-2, the virus that causes COVID-19, has been found in the faeces of infected patients in numerous studies. Stool may remain positive for SARS-CoV-2, even when the respiratory tract becomes negative, and the interaction with the gastrointestinal tract poses a series of questions about wastewater and its treatments. This review aims to understand the viral load of SARS-CoV-2 in faeces and sewage and its fate in wastewater treatment plants (WWTPs). The viral load in the faeces of persons testing positive for SARS-CoV-2 was estimated at between 5·103 to 107.6 copies/mL, depending on the infection course. In the sewerage, faeces undergo dilution and viral load decreases considerably in the wastewater entering a WWTP with a range from 2 copies/100 mL to 3·103 copies/mL, depending on the level of the epidemic. Monitoring of SARS-CoV-2 in sewage, although no evidence of COVID-19 transmission has been found via this route, could be advantageously exploited as an early warning of outbreaks. Preliminary studies on WBE seem promising; but high uncertainty of viral loads in wastewater and faeces remains, and further research is needed. The detection of SARS-CoV-2 in sewage, based on RNA sequences and RT-PCR, requires a shared approach on sample pre-treatment and on-site collection to ensure comparable results. The finding of viral RNA in stools does not imply that the virus is viable and infectious. Viability of CoVs such as SARS-CoV-2 decreases in wastewater - due to temperature, pH, solids, micropollutants - but high inactivation in WWTPs can be obtained only by using disinfection (free chlorine, UVC light). A reduction in the quantity of disinfectants can be obtained by implementing Membrane-Bioreactors with ultrafiltration to separate SARS-CoV-2 virions with a size of 60-140 nm. In sludge treatment, thermophilic digestion is effective, based on the general consensus that CoVs are highly sensitive to increased temperatures.

Keywords: Coronavirus; Faeces; Outbreak; SARS-CoV-2; Sewage; Wastewater treatment.

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Conflict of interest statement

Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Unlabelled Image
Graphical abstract
Fig. 1
Fig. 1
Virion structure of SARS-CoV/SARS-CoV-2 (permission obtained from Philippe Le Mercier, ViralZone, SIB Swiss Institute of Bioinformatics).
See this image and copyright information in PMC

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