Sodium hypochlorite disinfection of SARS-CoV-2 spiked in water and municipal wastewater

Greaves, Justin; Fischer, Robert J.; Shaffer, Marlee; Bivins, Aaron; Holbrook, Myndi; Munster, Vincent J.; Bibby, Kyle

Infectious severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has the potential to be collected in wastewater from mucus, sputum, and feces of infected individuals, raising questions about the appropriate handling and treatment of resulting wastewater. Current evidence indicates the likelihood of waterborne SARS-CoV-2 transmission is low; nonetheless, confirming the efficacy of disinfection against SARS-CoV-2 is prudent to ensure multiple barriers of protection for infectious SARS-CoV-2 that may result in the municipal and hospital wastewater stream. Sodium hypochlorite (free chlorine) is widely used for pathogen control in water disinfection applications. In the current study, we investigated the inactivation of SARS-CoV-2 in DI water and primary influent municipal wastewater by sodium hypochlorite (free chlorine) addition. Our results showed rapid disinfection of SARS-CoV-2, with less than 1 mg-min/L required for >3 log10 TCID50 reduction in DI water. More than 5 mg-min/L was required for 3 log10 TCID50 reduction in wastewater, suggesting potential shielding of the virus by solids. These results are consistent with expected virus inactivation by free chlorine and indicates the adequacy of free chlorine disinfection for inactivation of SARS-CoV-2 in water matrices.