Emerging Human Coronaviruses SARS-CoV-2 in Tunisian Wastewater

The severe acute respiratory coronavirus 2 (SARS-CoV-2) is the causative agent of the emerging infectious disease covid-19. The detection and measurement of SARS-CoV-2 in wastewater have been recently reported worldwide in various environmental studies. The molecular detection of emerging human coronaviruses SARS-CoV-2 in wastewater affords the ability to track viral pandemics. The present study aims to investigate this virus after wastewater treatment (WWT) in wastewater treatment plants (WWTPs). Forty-five wastewater samples were collected at different steps of the WWT process using a combined activated sludge procedure and two successive UV-C254 passage treatments at the scale of two Tunisian industrial WWTPs Charguia I and Mornaguia I. SARS-CoV-2 was detected using the multiplex real-time reverse transcription polymerase chain reaction method (real-time RT-PCR) and the Allplex Seegene SARS-CoV-2 kit, amplifying the four specific SARS-CoV-2 genes: E gene, S gene, N gene, and RdRP gene. Results: SARS-CoV-2 viruses were detected in 40% (18/45) of the collected wastewater sampled from these two industrial WWTPs. These results show the first detection of SARS-CoV-2 in northern Tunisian WWTPs. Likewise, SARS-CoV-2 viruses were detected at the exit of each step of the two considered biological and tertiary WWT procedures. These results also show the high resistance of these viruses to the experienced sewage purification processes. The treated effluents intended for agriculture reuse and discharges into the natural environments were of poor virological quality. This study investigated the new approach in environmental virology to track the spread, diffusion, and emergence of these infectious viral particles of SARS-CoV-2 in the environment.