RESUMEN
The municipal sewage carries the new coronavirus (SARS-CoV-2), shed by COVID-19 patients, to wastewater treatment plants. Proper wastewater treatment can provide an important barrier for preventing uncontrolled discharged of the virus into the environment. However, the role of the different wastewater treatment stages in reducing virus concentrations was, thus far, unknown. In this work, we quantified SARS-CoV-RNA in the raw sewage and along the main stages of the wastewater process from two different plants in Israel during this COVID-19 outbreak. We found that ca. 2 Log removal could be attained after primary and secondary treatment. Despite this removal, significant concentrations of SARS-CoV-RNA (>100 copies per mL) could still be detected in the treated wastewater. However, after treatment by chlorination, SARS-CoV-RNA was detected only once, likely due to insufficient chlorine dose. Our results highlight the need to protect wastewater treatment plants operators, as well as populations living near areas of wastewater discharge, from the risk of infection. In addition, our results emphasize the capabilities and limitations of the conventional wastewater treatment process in reducing SARS-CoV-RNA concentration, and present preliminary evidence for the importance of tertiary treatment and chlorination in reducing SARA-CoV-2 dissemination.
RESUMEN
SARS-CoV-2 is an RNA virus, a member of the coronavirus family of respiratory viruses that includes SARS-CoV-1 and MERS. COVID-19, the clinical syndrome caused by SARSCoV-2, has evolved into a global pandemic with more than 2,900,000 people infected. It has had an acute and dramatic impact on health care systems, economies, and societies of affected countries within these few months. Widespread testing and tracing efforts are employed in many countries in order to contain and mitigate this pandemic. Recent data has indicated that fecal shedding of SARS-CoV-2 is common, and that the virus can be detected in wastewater. This indicates that wastewater monitoring is a potentially efficient tool for epidemiological surveillance of SARS-CoV-2 infection in large populations at relevant scales. Collecting raw sewage data, representing specific districts, and crosslinking this data with the number of infected people from each location, will enable us to derive and provide quantitative surveillance tools. In particular, this will provide important means to (i) estimate the extent of outbreaks and their spatial distributions, based primarily on in-sewer measurements (ii) manage the early-warning system quantitatively and efficiently (and similarly, verify disease elimination). Here we report the development of a virus concentration method using PEG or alum, providing an important a tool for detection of SARS-CoV-2 RNA in sewage and relating it to the local populations and geographic information. This will provide a proof of concept for the use of sewage associated virus data as a reliable epidemiological tool.