A Modified ASM2d Model And Its Application In The Biological Pool Of A~2/O Process

Since the emergence of the activated sludge process, a number of mathematical models which proposed by domestic and foreign researchers were used for the characterization of activated sludge process and the relationship between the components. The ASM series launched by the International Water Association has been widely applied to the design, operation and management of instruction the sewage treatment plant at home and abroad. In the ASM model series, ASM2 d can be characterized by the nitrogen and phosphorus removal at the same time, therefore, has attracted a lot of attention. But the model involves multiple components(19), a complex biochemical reaction process(21), a large number of stoichiometric coefficients(22) and the kinetic parameters(43),resulting in the practical application in engineering is restricted. On this thesis, analyzed the pollutants removal efficiency of two A2/O systems(the A2/O pilot system and No.4 Wastewater Treatment Plant’s A2/O process).At the same time built a modified ASM2 d, combined reactor hydraulic characteristics and biochemical reaction kinetics to establish the pollutants removal model to simulate the nitrification, denitrification and biological phosphorus removal process of A2/O pilot system and the of xi ’an No.4 Wastewater Treatment Plant biological reaction tank, which verifies the feasibility of the model by comparing the simulation results with the measured values. The conclusions as follow:(1)The A2/O pilot system average removal efficiency of COD,NH4-N,TN and PO4-P are 82.49%, 96.19%, 67.43%, 85.04%. The removal efficiency of COD is less affected by external factors; the removal of NH4-N and TN are greatly influenced by temperature, when the temperature is below 15℃ NH4-N and TN removal efficiency decreased significantly; the nitrate with sludge into the anaerobic zone has a great influence on phosphorus removal.(2)The NO.4 Wastewater Treatment Plant average removal efficiency of COD, NH4-N, TN and PO4-P are 90.35%,97.18%,77.58%,94.38%. Through increase the volume of the anaerobic zone and anoxic zone, removal efficiency of TN and TP are greatly improved.(3)Using the modified ASM2 d model to simulate the nitrification, denitrification and biological phosphorus removal process of A2/O pilot system and xi ’an No.4 Wastewater Treatment Plant biological reaction tank, the results show that the simulated and observed values are very closely,the relative average error of ammonia, nitrate, phosphate simulation respectively less than 11%, 15% and 13.5%. It means that the modified ASM2 d model can more realistically reflect the wastewater treatment plant operation process, at the same time, the model can be used to forecast the water quality of wastewater treatment plant, as an auxiliary means of process control.