In this study, simulation results for a full-scale wastewater treatment plant (WWTP) of Erzincan city, which is located at the east of Turkey and serving 124,000 population equivalents, are presented. The dynamic behaviour of simultaneous carbon removal and nitrification process carried out in an Carrousel type aerator and also the clarification-thickening function of final settler were modelled employing activated sludge model 1 (ASM 1) and a dynamic model, respectively. In the first step of the study, detailed wastewater characterization required by the process models were performed and the variables such as readily (Ss) and slowly biodegradable (Xs) substrates were analysed with a respirometric technique. Simulations were performed using pre-compiled model and layout implemented in GPS-X simulation software. Daily values of parameters such as Soluble and Total COD, total nitrogen, suspended solids, NO3-N, NH4-N, organic-N, soluble inert substrate (S-I), S-s and X-s were used as input data. In model calibration, it was determined that the change in the default values of four model parameters gave a reasonable match for investigated variables. (c) 2004 Elsevier Ltd. All rights reserved.