We did a comparative kinetic study of biological oxidation of textile wastewater in an activated sludge, an activated sludge immobilized on biofilm, and a combination of TiO2 photocatalytic process and moving bed reactor biofilm system. Combining photocatalysis with a biological treatment could be a good strategy to remove non-biodegradable compounds. Mathematical models such as Grau second-order and modified Stover-Kincannon kinetic models were applied to determine the kinetic coefficients of COD removal process in biological treatment. The kinetic coefficients were determined by linear regression based on the experimental data. The results showed that the photocatalysis pretreatment of refractory compounds has a positive effect on the obtained kinetic parameters. As a result, COD content and color of wastewater were decreased; however, the saturation value constant and maximum utilization rate of the modified Stover-Kincannon kinetic models (by 63%) were increased relative to untreated wastewater by TiO2 as a pretreatment.