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 are scarce, because of the experimental challenges associated with the high reactivity of ozone toward viruses. Here, we established an experimental batch system that allows tailoring and quantifying of very low ozone exposures and simultaneously measuring virus inactivation. Second-order ozone inactivation rate constants (k_O) 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, Qβ, T4, and Φ174) were measured in buffered solutions. The k_O values of all tested viruses ranged from 4.5 × 10⁵ to 3.3 × 10⁶ M^-1 s^-1. For MS2, k_O depended only weakly on temperature (2-22 °C; E_a = 22.2 kJ mol^-1) and pH (6.5-8.5), with an increase in k_O with increasing pH. The susceptibility of the selected viruses toward ozone decreases in the following order: Qβ > CVEnv2 > EV ≈ MS2 > Φ174 ≈ T4 > HAdV > CVF ≈ CVEnv1. On the basis of the measured k_O and typical ozone exposures applied in water and wastewater treatment, we conclude that ozone is a highly effective disinfectant for virus control.