Inactivation of Microorganisms in Seawater by a Combined System of Photocatalysis, Hydrogen Peroxide and Ultraviolet Irradiation

The inactivation of microorganisms in seawater using a combined system of photocatalysis, hydrogen peroxide and UV-C irradiation was investigated. It was noted that the photocatalysis reaction time required for the complete suppression of photoreactivation in coliforms after UV-C irradiation was much shorter than that required for the complete inactivation of coliforms by direct disinfection of filtrated seawater. The minimum concentration of hydrogen peroxide required for the complete suppression of photoreactivation in coliforms after UV-C irradiation was lower than that required for the complete inactivation of coliforms by direct disinfection of filtrated seawater. The photocatalysis reaction time required for the complete inactivation of coliforms was the shortest in the combined system of UV-C→H2O2→TiO2/UV-A, which resulted in the largest amount of disinfected seawater. The stable treatment using teh UV-C→H2O2→TiO2/UV-A combined system was undertaken in the pilot tests plant for 6 days, during which bromate ion, and oxidation by-product, was not detected in the treated seawater.