Combined ozone and ultraviolet inactivation of Escherichia coli

by Savant, Gaurav.

29 The kinetics of Escherichia coli inactivation were studied using ultraviolet (UV) radiation, ozone, and UV and ozone (UVO) in combination in a batch reactor at varying pH levels (6, 7, and 8) and at a constant temperature of 25°C. The inactivation kinetics for all three treatment processes was pseudo first order, and the reaction rate constants were considered to be additive such that a combined reaction rate could be obtained by adding the kinetic rates of the processes applied and numerically small rates could be neglected in the computation of the combined rate. Statistical tests (ANOVA) performed on the inactivation data indicated no apparent effect of pH on the kinetics of the processes. It was found that the UVO process was the most efficient in inactivating E. coli. The increase in the inactivation rate with the UVO process is attributed to synergetic activity of UV and ozone which results in the generation of hydroxyl radicals from ozone decomposition.