"In this study, the performance of a flat plate photocatalytic reactor for degrading and mineralising storm and wastewater pollutants is investigated. This research aims to lay the groundwork for the performance of the flat plate photocatalytic reactor using computational fluid dynamics (CFD) simulation as a first step. Then an extensive study is performed to evaluate the role of mixing and turbulence promoters in the photocatalytic reactor to improve its design to meet the needs of a prototype photocatalytic reactor. The CFD simulation results are validated with experimentally measured data under various flow conditions. The experimentally measured velocity and benzoic acid concentration was found to be in good agreement with the results of the simulation. The results showed that the model can accurately predict the velocity and the outlet concentration of benzoic acid for various hydrodynamic conditions. Using various turbulence sub-models, the flow profile in the flat plate reactor was simulated for various flow conditions. No discernible variation on the flow profiles was observed regardless of the turbulence models tested. Furthermore, the performance of the reactor for the degradation of phenol as a model pollutant was predicted which was observed to decrease with increased flow rates"--Abstract.