Contact-Adsorption-Regeneration (CAR) process is a cost-effective system for wastewater treatment and has a potential for application in less-developed regions. To offer a better understanding of this process, a mathematical model was established on the basis of Activated Sludge Model No. 1 (ASM1) and by incorporating the adsorption and different hydrolysis processes. The model predictions were compared with the measured data in terms of effluent concentrations and removals of both chemical oxygen demand (COD) and NH(4)(+)-N. A good agreement between the predicted and measured data was observed, indicating that the model was capable of predicting the rapid adsorption, COD removal and nitrification processes in the CAR system. This work provides an experimental and theoretical basis for the application of the CAR process in less-developed regions. (C) 2010 Elsevier Ltd. All rights reserved.