Kinetics of Ozone Disinfection in Completely Mixed System

Abstract

Development of models that describe inactivation kinetics with ozone is made difficult by unstable ozone residual, rapid rate of inactivation process, and improper interpretation of inactivation data. Consequently, there are great discrepancies as to both the order of inactivation and the magnitude of reaction rate constants in the rate expressions. In this paper, an innovative completely mixed reactor (continuously stirred tank reactor [CSTR]) was used. Five models, representing the three basic phenomena of inactivation, were fit to the experimental data by applying the rigorous statistical approaches (the classical nonlinear regression or the error‐in‐variables method), where required. It was shown that both the comprehensive model developed herein and the Chick‐Watson model were adequate in predicting the bacterial survival. The empirical coefficient of dilution was found to be as high as 3.3, strongly suggesting that ozone concentration was a much more important factor than contact time in determining the efficiency of the disinfection process. The activation energy of overall inactivation was 85 kJ/mol, indicating that the rate of bacterial inactivation with ozone is chemical reaction‐controlled.