The management of wastewater treatment plants to comply with new strict effluent criteria is a great concern: the activated sludge modeling, when supported by an accurate calibration process, could be an essential tool for this purpose. In the present paper, three WWTPs were characterized in order to support their up-grade. Influent characteristics and activated sludge performances were studied by application of respirometry. Plant operations were simulated by BioWin software (EnviroSim Associates Ltd., Canada). The goodness of the simulation, checked by the calculation of the average relative deviation between measured and simulated data, demonstrated that the model was able to predict the plant performances.
