Comprative evaluation of Advanced Oxidation Processes (AOPs) for reducing SARS-CoV-2 viral load from campus sewage water

Although the presence of SARS-CoV-2 fragments in raw sewage water are not much concerning, since it is a new pathogen and its fate in the environment is poorly understood; therefore efforts are needed for their effective removal. In under-developed countries with poor sewersheds and sanitation practices, the raw sewage water might come in contact with rivers and other water bodies and is generally used by the population for various purposes including drinking water. Hence it is important to properly treat sewage water to reduce public health risks, if any. Our study evaluated various advanced oxidation processes (AOPs) for disinfection of SARS-CoV-2 from sewage water collected from the academic institutional residential campus. The present study is the first report showing hydrodynamic cavitation (HC) used to reduce the SARS-CoV-2 viral load from sewage water. Additionally, we have also evaluated hybrid techniques like HC/O3, HC/O3/H2O2, HC/H2O2, O3/UV, UV/H2O2, UV/H2O2/O3, and O3/H2O2 for the minimization of the SARS-CoV-2 viral load from sewage water. The sewage water treatment techniques were evaluated based on its viral concentration-reducing efficiency by comparing it with the same raw sewage water sample. However, ozone alone and its combination with other disinfecting techniques (like HC, UV, and H2O2) showed >95% SARS-CoV-2 specific RNA-reducing efficiency (also known as viral load). The AOPs treated sewage water was subjected to total nucleic acid isolation followed by RT-qPCR for viral load estimation. Interestingly, all sewage water treatment techniques used in this study significantly reduces both the SARS-CoV-2 viral load as well as PMMoV (faecal indicator) load.