Simulation of the photocatalytic reactor using finite volume and discrete ordinate method; a parametric study

Advanced oxidation processes (AOPs) for wastewater treatment have received a great deal of attention in recent years. Photocatalytic oxidation processes decompose water pollutants using nano-structured photocatalyst materials, titanium dioxide (TiO2) and ultraviolet irradiation. Although there is extensive experimental research in this field, designing a photoreactor for water treatment is still a challenge. An effectual approach to this issue is the application of computational fluid dynamics. Performance of the catalyst, which is activated by UV irradiation, is one of the important factors affecting photoreactor efficiency. In case of poor UV radiation distribution inside the reactor, the reactor performance decreases due to catalyst inactivity. In this study, a computational fluid dynamics model for the simulation of radiation distribution inside a photoreactor was developed and evaluated against experimental data. Simulations were then carried on different catalyst loading, lamp power and wall reflectivity. The performed analysis showed that at low concentration of catalyst (0.4 g/L), the reaction rate increases up to 50% by increasing the wall reflectivity to 98%, this is due to small absorption coefficient of the medium. At high catalyst concentration (0.6 g/L), the increase in reaction rate is only 5% because the radiation amount that reaches the reactor walls is negligible. At the lamp power of 2P and P, the reaction rate increases up to 12.2 % and 11% respectively which means only 1% increase in reaction rate while increasing lamp power.