Bactericidal Effect of UVC-Irradiated Water Containing Natural Organic Matter

摘要

UVC-irradiation is widely used as an effective method to disinfect drinking water. Even though UVC inactivates most pathogenic organisms momentarily, this treatment was not believed to leave any "residuals" with bactericidal properties. UV-irradiation of humic water is followed by the release of low molecular weight substances like fatty acids, carbonyl compounds, and amino acids, which may serve as nutrients for heterotrophic bacteria (1) and thus, stimulate bacterial growth. In some cases, however, unknown toxic or long-lived reactive species were produced, which hampered the growth of aquatic organisms (2-4). In the present investigation we have tested the bactericidal effect of UVC-irradiated water, containing solutions of 9 different Reverse Osmosis (RO) isolates. The aim was to find out: (a) whether UVC-irradiation will result in the "production" of bactericides, (b) whether potential effects depend on the nature of NOM, and (c) whether potential bactericidal effects would last over a longer period of time.