MODELING OF KINETICS AND REACTOR FOR WATER-PURIFICATION BY PHOTOOXIDATION

The removal of low levels Of organics is an important problem in water treatment and ultrapure water production plants. Photo-oxidation or phototransformation of trace organics can play a unique role in water purification. In this paper, the modelling of kinetics of selected photochemical reactions in which ultraviolet (UV) light irradiation is combined with hydrogen Peroxide (H2O2) or ozone (O3) is reviewed. The processes exhibit a synergistic effect leading to the formation of reactive hydroxyl radicals which are capable of oxidising ''refractory'' intermediates and a wide range of organics. The modelling of photoreactors for water purification by the UV/H2O2 and UV/O3 synergistic routes is discussed. The models should take into account the reaction kinetics and the rate of light energy absorption which can be obtained from an analysis of the radiation field in the photoreactor. A validated mathematical model is essential for scale-up and design of photoreactors for water purification plants.