The Basic Phenomena and Mechanisms of Disinfection by Ozone Yeh Shin-Cheng, Y.H. Yu, K. H. Chen, Taiwan. The influence of various impurities in water on the magnitude of disinfecting effects by ozone is studied. Different organic matters such as TOC, alkalinity, and turbidity are the factors considered in this study. The results indicate that the factors in the order of negative effects over the disinfection by ozone are as follows: phenol, humic acids, and glucose. In batch reactors, organic matters will cause increase of the critical effective ozone concentrations; whereas the complete kill of E. coli will be delayed in continuous flow reactors due to their existence. Also, alkalinity and turbidity will both lower the disinfecting power of ozone and the former is the more influential one. Previously noted "all-or-none" effect was observed in this study during batch experiments. By comparative work, our results indicate that ozone is the most effective disinfecting agent used. Nevertheless, final addition of chlorine is still needed to protect the water from recontamination provided ozone or activated oxygen is used as the precedent disinfectant. Source: 2nd International Symposium on Ozone Applications Havana, Cuba - Mach 24-26, 1997.