A dynamic simulation model has been developed and validated for the 1.4 million p.e. capacity Budapest Central Wastewater Treatment Plant to support intensification, process development and risk assessment. By the integration of both the biological and physico-chemical processes the technological design of separated units becomes possible as well as the exploration of the connections within the system. The calibration of the model parameters for an operating treatment plant is the key requirement for the proper application of dynamic simulation tool to optimize operational and maintenance conditions and specify the potential development areas. We have done a one-year period of validation which included sensitivity analysis and the simulation of time intervals in the same way as in the calibration process. At the same time we investigated the suitability of the simulation system for real-time operation optimization. As conclusion we ascertained that due to the computational power necessity of a properly detailed model, it is not applicable for real-time operation optimization, nevertheless it is suitable for the detection of the system reactions for long-term changes of the influent load. This means that a properly functioning model is applicable for indicating the development directions.