Modeling an ozone bubble column for predicting its disinfection efficiency and control of DBP formation

The prediction models describing the disinfection efficiency, the formation of aldehydes and the control of DBPs in the ozone bubble column were developed through a systematic approach. At low applied ozone doses, the predicted Ct values increased slightly with increasing gas flow rate. As the applied ozone dose increased, the influence of the gas flow rate on the Ct parameters became more apparent. The aldehyde formation increased to a maximum value when the ozone doses increased from 0.2 to 1.1 mg O(3/)mg TOC; whereas a further increase of the ozone dose to 1.8 mg O-3/mg TOC decreased the aldehyde concentrations. The concentration profiles of aldehyde and DBP in the ozone bubble column were modeled at the different ozone dosages and compared with the experimental data. The utilization of a two-step reaction mechanism predicted the aldehyde formation reasonably well. Furthermore, the relationship between the optimization of ozone dosages and the disinfection efficiency, aldehyde formation and control of DBPs was discussed. (C) 1999 Elsevier Science Ltd. All rights reserved.