Approaches applied to detect SARS-CoV-2 in wastewater and perspectives post-COVID-19

Currently, SARS-CoV-2 has been detected in the influent of wastewater treatment plants (WWTP), pumping stations, manholes, sewer networks and sludge of WWTP and facilities of countries as France, Spain, Italy, Netherlands, United States, Australia, Ecuador, Brazil and Japan. Although this virus has been detected in the wastewater streams, there is no robust method for its detection and quantification in wastewater. This review compiled and analyzed the virus concentration approaches applied to detect the SARS-CoV-2, besides to provide insights about the methodology for viral concentration, limit of detection, occurrence, persistence, and perspectives post-COVID-19 related with the implications of the virus presence in wastewater. The SARS-COV-2 detection in wastewater has been related to virus concentration methods, which present different recovery rates of the virus. The most used viral concentration methods have been the polyethylene glycol (PEG) for precipitation of viral material and the ultrafiltration at molecular weight level. After viral concentration, the detection and quantification of SARS-COV-2 in wastewater are mainly via quantitative reverse transcription polymerase chain reaction (RT-qPCR), which is the clinical assay adapted for environmental purposes. Although in some experiments the positive control during RT-qPCR is running a surrogated virus (e.g., Mengovirus or Dengue virus), RT-qPCR or reverse transcription droplet digital PCR (RT-ddPCR) targeting the gene encoding nucleocapsid (N1, N2 and N3) of SARS-COV-2 are highly recommended to calculate the limit of detection in wastewater samples. Current results suggest that a rigorous methodology to elucidate the positive cases in a region from genomic copies in wastewater is needed.