SARS-CoV-2 in the environment: Contamination routes, detection methods, persistence and removal in wastewater treatment plants

Abstract

The present study reviewed the occurrence of SARS-CoV-2 RNA and the evaluation of virus infectivity in feces and environmental matrices. The detection of SARS-CoV-2 RNA in feces and wastewater samples, reported in several studies, has generated interest and concern regarding the possible fecal-oral route of SARS-CoV-2 transmission. To date, the presence of viable SARS-CoV-2 in feces of COVID-19 infected people is not clearly confirmed although its isolation from feces of six different patients. Further, there is no documented evidence on the infectivity of SARS-CoV-2 in wastewater, sludge and environmental water samples, although the viral genome has been detected in these matrices. Decay data revealed that SARS-CoV-2 RNA persisted longer than infectious particle in all aquatic environment, indicating that genome quantification of SARS-CoV-2 does not imply the presence of infective viral particles. In addition, this review also outlined the fate of SARS-CoV-2 RNA during the different steps in the wastewater treatment plant and focusing on the virus elimination along the sludge treatment line. Studies showed complete removal of SARS-CoV-2 during the tertiary treatment. Moreover, thermophilic sludge treatments present high efficiency in SARS-CoV-2 inactivation. Further studies are required to provide more evidence with respect to the inactivation behavior of infectious SARS-CoV-2 in different environmental matrices and to examine factors affecting SARS-CoV-2 persistence.

Keywords: Decay; Detection methods; Fate; SARS-CoV-2; Wastewater; Wastewater treatment plants.

Graphical abstract

Fig. 1

Potential modes of environmental contamination by SARS-CoV-2. Dashed arrow indicates suspected contamination routes where no data has been collected.

Fig. 2

log₁₀ k of infections SARS-CoV-2 and SARS-CoV-2 RNA in wastewater and other water matrices at different temperatures. Dashed lines represent the linear regression fits for each target. Individual k values are obtained from previous studies and presented in Table S1. log₁₀ k of infections SARS-CoV-2 and SARS-CoV-2 RNA in wastewater and other water matrices at different temperatures. Dashed lines represent the linear regression fits for each target. Individual k values are obtained from previous studies and presented in Table S1.