Deciphering the virucidal potential of hydroxyl radical during ozonation: Implications for waterborne virus inactivation

The heightened public health risks associated with viral contamination in water have led to a strong emphasis on effective disinfection strategies. Ozone is a potent disinfectant widely employed for the inactivation of pathogens, yet comprehensive reports detailing the virucidal efficacy of hydroxyl radical (•OH) generated during ozonation are limited. The present research meticulously deciphered the role and influencing factors of •OH during ozone disinfection processes, elucidating how •OH enhanced ozone-mediated virus inactivation from both kinetic and molecular biological perspectives. The inactivation rate constants of ozone-derived •OH for Phi6 (9.67 × 10¹⁰ M^-1 s^-1) and PhiX174 (3.85 × 10¹⁰ M^-1 s^-1) were 4-5 orders of magnitude higher than those of ozone molecules. At 20 °C and pH 7.0, the contribution of •OH to the reduction of viral infectivity has been quantified as ranging from 11.3 % to 52.7 %. The yield of •OH increased notably as pH rose from 6.0 to 8.0, which was the principal cause for the accelerated apparent virus inactivation rates by ozone. An elevation in temperature (10-30 °C) had a negligible impact on •OH yield but facilitated virus removal by enhancing the reactivity of oxidants with viral particles. The damage inflicted on the viral genome by •OH vastly surpassed that caused by ozone, with the log reduction in gene copies in the presence of •OH being 297-343 % higher than the effect observed with ozone alone. The potential interaction sites of ozone and •OH with viral genetic material were predicted using Density Functional Theory static calculations and further compared. The present research offers comprehensive insights into the inactivation capabilities and underlying mechanisms of •OH for the effective control of waterborne viruses, establishing a theoretical foundation for employing the advanced oxidation properties of ozone-derived •OH in developing innovative water disinfection strategies.