Three full-scale municipal sequential batch reactor (SBR) wastewater treatment plants (WWTPs) were investigated by dynamic simulation studies using ASM1.All three WWTPs showed similar kinetic and stoichiometric conditions in the SBR population behaviour after calibration of the models. The simulation results detected only a discrepancy to the ammonia online data during and shortly after shock loading under anoxic and anaerobic conditions that so far could not be adjusted by the ASM1 model. However, these differences did not severely affect the quality of the simulations nor the effluent flows. Additionally, in all cases a dynamic alpha factor curve occurred during the aeration phases that was verified by further oxygen transfer measurements. This might reveal new aspects for the process control, design and simulation of SBR WWTPs. A short lag phase was detected in many cases at the beginning of the first aeration phase.