The water train of three WWTPs have been modelled following the procedures of the Benchmark Simulation Model (BSM) platform (Gernaey et al., 2014). Additionally the aeration system has been modelled to evaluate airflows and energy performance. The results for the airflow model are presented. The chosen airflow model is shown to be easy to apply and calibrate and robust for practical modelling cases. By simply adjusting the SOTE-polynomial, number of diffusors and airflow limitations the model replicates the real data at a level of detail suitable for most purposes where the evaluation is based on longer time averages. For peak demand evaluation the whole treatment model with influent characterization, model calibration and controllers need to be more detailed than done here. Modelling the airflow is important to allow for evaluation of air consumption, aeration energy performance and for communication of simulation results to plant staff and operators.