Simulation And Optimization Of A~2/O Wastewater Treatment Process Based On Model ASM2D

The construction of sewage treatment plant is an effective means to solve the problem of urban water pollution. Under the new effluent discharge standards, nitrogen and phosphorus removal have been compulsively included. A2/O process has been developed in the last two decades as a biological nutrient removal technology. For improving nitrogen and phosphorus removal efficiency in the reaction system and optimizing discharge water quality, the sewage treatment process should be finely manipulated on the basis of all operating conditions. In this paper, a simulation program based on Matlab7.0 platform was designed according to ASM2D Model developed by the International Water Association, and then was applied for chemostat simulation and optimization of principal processing parameters on the newly constructed sewage treatment station with A2/O process in Bole City Airport.The main contents include:(1) The common activated sludge processes and their systematic fundamental structures were described, and the progress of both international and domestic activated sludge models was reviewed.(2) The components, mechanism and reaction process of ASM2D model were discussed and a systematic model combined ASM2D with Takacs Secondary Settling Tank Model was developed.(3) The program framework for the systematic activated sludge model combined ASM2D with Takacs Secondary Settling Tank Model was set out, and the assumptions for the systematic model were proposed. Accordingly, the calculation methodology for inflow and backflow components was determined. Lastly, the mass balance equations for the anaerobic, anoxic and aerobic tanks in A2/O process based on the Law of Mass Conservation were listed in accordance with ASM2D Model.(4) The sewage treatment plant project in Bole City Airport and its start-up operation were generally reviewed. The measured airport sewage quality as inflow component was input into ASM2D Model for the sensitivity analysis of major chemometric and kinetic parameters and YA value was therefore corrected to 0.32 g (COD)/g(N). Finally, based on the model the mixed liquid return ration (MLRR), sludge age (0) and return ratio (SRR), and dissolved oxygen (DO) in the whole process were computed. The results showed that Bole Airport sewage treatment plant at its design would be optimally operated in terms of COD, N and P removal efficiency and energy consumption under the conditions of MLRR=200%, SRR=75%,0=9.7 d, and DO=2mg/L...