Computer Simulation Of Single-Stage Activated Sludge Process For Municipal Wastewater Treatment

The Activated Sludge Model No.3 (ASM3) was proposed by International Water Association (IWA) based on the Activated Sludge Model No.1 (ASM1) and No.2 (ASM2). It relates to ASMl and corrects for some defects of ASMl. In ASM3 organic nitrogen is regarded as a part of organic materia, and storage of soluble organic substrates is added as an intermediate. The lysis process is exchanged for an endogenous respiration process, which makes it more approach the real biological process. Moreover, ASM3 introduces the composition matrix 1k,i together with the stoichiometric matrix vj.i.In this paper, a mathematical model for activated sludge system was constructed based on ASM3 and Takacs settling model, with the transfer process model. Then we programed the ASM3 procedure using Visual Basic 6.0 based on Windows XP operation system. The procedure was adjusted by the COST simulation benchmark and the differences between ASM3 and ASMl were analyzed. ASMl had been testified according with the COST. The simulation of model components in the course of the system's startup by ASM3 had a little difference with ASM1 due to their different components and reaction mechanisms. But the simulation of the effluent TCOD and TN by ASM3 were relatively accurate and the errors were below 5% .The procedure was used to simulate the Step-Feed Anoxic/Oxic Activated Sludge Process. The steady state simulation results and the dynamic ones correlate well the measured values. In addition, we changed the plant's operating and controling parameters in the model to analysis the influence of these parameters on the effluent water quality. And the predicted results accorded with the actuality.Moreover, the definition methods of model components were analysised and summarized.