KINETICS OF ESCHERICHIA-COLI INACTIVATION WITH OZONE

The kinetics of Escherichia coli inactivation with ozone were investig ated with semi-batch and continuous-flow tubular reactors in solutions buffered with phosphate at pH 6 and 8, temperatures ranging from 5 to 25 degrees C, and in the presence (0.01 hr) and absence of radical sc avenger tert-butanol. Ozone concentrations and contact times investiga ted ranged from 6 to 41 mu g/l, and 1.8-33s, respectively. Inactivatio n kinetics were found to be first-order with respect to both ozone con centration and active microorganism density. The overall second-order rate constant was 130 l/(mg s) at 20 degrees C, and the corresponding activation energy was 37,100 J/mol. Experimental results corresponding to tests performed at pH 6 and 8, and in the presence (0.01 M) and ab sence of radical scavenger tert-butanol, confirmed that dissolved mole cular ozone was primarily responsible for E. coli inactivation in the range of experimental conditions investigated. (C) 1997 Elsevier Scien ce Ltd.