Bacterial inactivation kinetics of a photo-disinfection system using novel titania-impregnated kaolinite photocatalyst

We recently developed a novel titania-impregnated kaolinite (TiO2–K) catalyst and an annular slurry photoreactor (ASP). The present study was to determine the optimal operational factors: TiO2–K loading, pH, aeration rate, bacterial population and irradiation time, and their impact on disinfection activity and kinetics of a sewage-isolated Escherichia coli sp. (ATCC 11775). The inactivation kinetics were evaluated with experimental data and three Hom series empirical models, namely; the Hom model, modified-Hom model and Hom–Power model. The bacterial inactivation rate in the ASP–TiO2–K system was pH-independent up to pH 7.0. At optimum conditions, 120 min irradiation time was required to achieve 5 bacterial log-reduction units for an average bacterial inoculum size of 8.0 × 106 CFU mL−1. A sigmoid-shape bacterial inactivation profile with strong shoulder and prolonged tailing characteristics was proven. The inactivation kinetic studies revealed that the modified Hom model appeared to be the best empirical model that could represent the disinfection kinetics, with three different inactivation characteristic regions in the ASP–TiO2–K system.