An activated sludge 2D model was used for optimizing the process design of nitrogen and phosphorus removal in urban sewage plant.Simulation model of A2/O process was constituted

and the model was calibrated to optimize the operation parameters.Such optimization design was compared with the traditional activated sludge process design and trial calculation method.The simulated results acquired are basically approximate to experimental values.Compared with the other two methods

the optimization design presented here has a big reduction in the sewage plant capital construction expense and running cost.Although the effluent quality has a slight drop

it still satisfies the national standard for first-level B draining.Hence

the activated sludge 2D model is capable to the optimization design and the control for sewage plants. Under the premise of meeting the requirements of effluent standards

the expenses of plants can be reduced. It also provides a theoretical guide for future process design.