Batch scale activated sludge kinetic studies were undertaken for the treatment of pet food wastewater characterized by oil and grease concentrations of up to 21,500 mg/L, COD and BOD concentrations of 75,000 and 60,000 mg/L, respectively as well as effluent from the batch dissolved air flotation (DAF) system. The conducted kinetics studies showed that Haldane Model fit the substrates and biomass data better than Monod model in DAF-pretreated wastewater, while the modified hydrolysis Monod model better fit the raw wastewater kinetic data. For the DAF pretreated batches, Haldane Model kinetic coefficients k, K-S, Y and K-i values of 1.28-5.35 gCOD/gVSS-d, 17,833-23,477 mg/L, 0.13-0.41 mgVSS/mgCOD and 48,168 mg/L, respectively were obtained reflecting the slow biodegradation rate. Modified hydrolysis Monod model kinetic constants for the raw wastewater i.e., k, K-S, Y, and K-H varied from 1-1.3 gCOD/gVSS-d, 5580-5600 mgCOD/l, 0.08-0.85 mgVSS/mgCOD, and 0.21-0.66 d(-1), respectively. (c) 2005 Elsevier Ltd. All rights reserved.