Decomposition and Utilization of Ozone in Water Treatment Reactor with Ultraviolet Radiation

The decomposition rate of ozone in the gas phase with ultraviolet irradiation was determined in a thin, rectangular channel reactor where the distributions of ozone concentration and UV irradiation were minimized. The experiment was carried out under conditions which were encountered in normal water treatment units. The overall quantum yield of ozone decomposition was correlated by experimental equations. Estimated values of the overall quantum yield based on elementary reactions and kinetic data in the literature were much smaller than the experimental data. The utilization efficiency of ozone in the ozone/UV process for water treatment was simulated with a simple model reactor. Excessive UV radiation is likely to destroy gaseous ozone before it is transferred into the liquid phase. The optimum value of UV irradiance depends on the apparatus and operation conditions.