Research On ASM2D Simulation And Mechanism Of Biological Nutrient Removal

The research of this thesis emphasized on the biochemical metabolism of BNR in A/A/O process fed with municipal wastewater, combining with activated sludge model No.2D.Firstly, the process paramenters that influenced the treatment efficiency of biological nutrient process were investigated. The results indicated that the optimal process operation was under the internal return ratio of 200%, an anaerobic hydraulic retention time (HRT) of 1.6 h and a solid retention time (SRT) of 12 days. The effluent concentratons could comply with the first class discharge standard of pollutants for municipal wastewater treatment plant. Based on ASM2D, A/A/O activated sludge model was programmed to simulate the lab-scale experimental results after the sensitivity of key parameters was analysed. The resulted indicatd the simulated COD simulation precision was above 90%. The simulating precision of ammonia and P concentrations were above 90% and 88% in anaerobic and anoxic stages, respectively. Although the simulating precisions of them were low in aerobic stage, absolute errors were lower than 1.0, 0.8 mg/L, respectively. The simulating precision of nitrate concentration was higher than 86% under the SRT of 12 and 15 days, while under the SRT of 8 and 10 days the simulating precision was only in range of 55 to 75% and absolute errors were in range of 2.0 to 4.4 mg/L because of simplification of nitrification reaction. In a whole, the calibrated model could satisfactorily simulate the process operation. After simulation, the optimal internal return ratio, hydraulic retention time and sludge retention time were 160%, 2.0 h and 13 days, respectively, which were close to experimental results. As a effective tool, ASM could successfully help experimental research and optimize the operating management of wastewater treatment plant.During the experimental research, it was found that denitrification occurred in anaerobic stage, and P uptake occurred in anoxic stage. Therefore, the effects of internal return ratio and SRT on the anoxic denitrifying phosphorus removal occured in...