Kinetics of inactivation of waterborne enteric viruses by ozone

Ozone is an effective disinfectant against all types of waterborne pathogens. However, accurate and quantitative kinetic data regarding virus inactivation by ozone is scarce, due to the experimental challenges associated with the high reactivity of ozone towards viruses. Here, we established an experimental batch system that allows tailoring and quantifying very low ozone exposures and simultaneously measuring virus inactivation. Second-order ozone inactivation rate constants (kO3-virus) of five enteric viruses (laboratory and two environmental strains of coxsackievirus B5: CVF, CVEnv1 and CVEnv2, human adenovirus: HAdV, and echovirus 11: EV) and four bacteriophages (MS2, Q, T4 and Φ174) were measured in buffered solutions. The kO3-Virus of all tested viruses ranged from 4.5 x 105 to 3.3 x 106 M-1s-1. For MS2, kO3-MS2 only depended weakly on temperature (2 – 22 °C, Ea = 22.2 kJmol-1) and pH (6.5 – 8.5), with an increase of kO3-MS2 with increasing pH. The susceptibility of the selected viruses towards ozone decreases in the order Qbeta > CVEnv2 > EV = MS2 > Φ174 = T4 > HAdV > CVF = CVEnv1. Based on the measured kO3-Virus and typical ozone exposures applied in water and wastewater treatment, we conclude that ozone is a highly effective disinfectant for virus control.