Detection of SARS-CoV-2 RNA in Sewage and Sludge from a Wastewater Treatment Plant in Dhaka, Bangladesh: A Pilot Environmental Surveillance Study

Background: SARS-CoV-2 in sewage and aquatic environments may contribute to environmental dissemination of the virus. This study investigated the presence of SARS-CoV-2 RNA in sewage, sludge, and selected surface water sources in Dhaka, Bangladesh, and assessed related physicochemical parameters. Methods: Samples were collected from sewage pumping stations, one sewage treatment plant (STP), and selected rivers and ponds between September 2020 and January 2021. SARS-CoV-2 RNA was detected by RT-qPCR following nucleic acid extraction using a commercial kit. Temperature, pH, total dissolved solids (TDS), and dissolved oxygen (DO) were measured using portable instruments and conductivity was calculated from the TDS value. Results: SARS-CoV-2 RNA was detected in 57.1% of sewage samples and 53.3% of sludge samples. No viral RNA was detected in treated effluent from the STP, river, or pond, samples. River water showed little variation in physicochemical parameters, whereas pond and sewage samples exhibited differences in pH, conductivity, TDS, and DO. Conclusion: The presence of SARS-CoV-2 RNA in untreated sewage and sludge, but not in treated effluent, indicates that SARS-CoV-2 RNA was undetectable in the treated effluent. Further studies are needed to better understand the environmental persistence of SARS-CoV-2 in aquatic systems in Bangladesh.