Effect of Suspended Solids on Inactivation of Poliovirus and T2-Phage by Ozone

Abstract

This study was conducted to quantify the effects of suspended solids on virus inactivation by ozone and to develop guidelines for ozone dosages in disinfection using poliovirus and T2-phage. The curve of virus count reduction could be divided into three phases: an initial large reduction which occurred within 30 seconds of contact between the viruses and ozone; a subsequent logarithmic reduction; and finally, a slow reduction in response to decreasing ozone concentrations. The reduction of the viruses by ozone is expressed well by the Collins-Selleck Model. The presence of suspended solids significantly reduced the rate of virus inactivation. Using data obtained in this study, the model equation gives the following estimates: if 99.99% inactivation is required with a contact time of 5 minutes, an ozone residual of 0.6 mg/l is necessary when suspended solids are not present; with kaolin levels of 1 and 10 mg/l, ozone residuals of at least 0.9 and 3.7 mg/l, respectively, are necessary for 99.99% inactivation in 5 minutes. If more than 1 mg/l of an autoclaved activated sludge is added to the water, the commonly applied dose of ozone is not sufficient to produce more than a 4 log10 reduction in 5 minutes.