Inactivation of enteric adenovirus and feline calicivirus by ozone

Little information is available regarding the effectiveness of ozone on the inactivation of caliciviruses and enteric adenoviruses. Inactivation experiments were conducted with feline calicivirus (FCV), closely related to the human caliciviruses based on nucleic acid organization and capsid architecture, and adenovirus type 40 (AD40). Experiments were carried out in buffered disinfectant demand free water at pH 7 and 5°C. Ct values; concentration of ozone multiplied by contact time with virus; were determined from application of the efficiency factor hom (EFH) model. Ct values for 4-log (99.99%) ozone inactivation at 5°C and pH 7 ranged from 0.07 to 0.60 mg/l min for AD40 and <0.01 to 0.03 mg/l min for FCV. Ct values listed in the US environmental protection agency "Guidance Manual for Compliance with Filtration and Disinfection Requirements for Public Water Systems Using Surface Water Sources" were higher than Ct values generated by this study. Very low ozone residuals (<0.01(mg/l) substantially inactivated FCV and AD40 under the studied conditions.