해수 오존처리시 브로민 생성과 소독효과

Abstract

Pathogenic and/or invasive organisms are problematic in ballast water, desalination plants and aquaculture systems for both ecological and economic reasons. In a desalination plant, the presence of microorganisms can lead to biofouling of the ultrafiltration and seawater reverse osmosis membrane equipment. Meanwhile, in the aquaculture industry, some pathogenic organisms cause serious fish diseases, which can result in mass die-offs. Various disinfection techniques such as ozonation, ultraviolet irradiation, electrolysis and chlorination, have been applied to remove pathogenic organisms from seawater environments. The purpose of this study was to develop a kinetic model for the prediction of residual ozone and bromine concentrations in seawater following ozonation, taking into consideration the ozone dose, water salinity, and pH. Ozone chemistry in saltwater is considerably different from that in fresh water because saltwater contains much higher concentrations of dissolved anions and cations (e.g., chloride, bromide, magnesium, sulfate) than fresh water. Salinity greatly affects the formation of residual ozone and bromine during saltwater ozonation. Unlike freshwater ozonation, there is no hydroxyl radical formation in seawater ozonation because ozone decomposition is considerably faster in water containing bromide. Therefore, seawater ozonation involves the initial unstable oxidant (ozone) and a secondary, more stable oxidant (bromine) for disinfection. This study also aimed to evaluate the performance of ozone and bromine disinfection using E. coli. The log inactivation of E. coli with ozone and bromine was 2.5 and 4 log, respectively. The log inactivation of E. coli with seawater ozonation was 5.8 log.