An advanced model for the optimization of the title processes was developed by using a multi-threaded predictive control system. The activated sludge method was used in 2 biol. reactors, where denitrification and nitrification and removal of org. C compds. and dephosphatation took place. A sewage aeration and movement in bioreactors was generated by using agitators or sludge recirculation. The computer model of the wastewater treatment plant was developed in a com. environment. An activated sludge model was used to model biochem. processes, including org. C and N removal and transformations involving bacteria using the ability to store P in cell biomass. Then, quantitative and qualitative parameters were identified and the model was calibrated by det. the agreement of simulation results with measured data.