Mathematical Model And Process Optimization Of Multi-AAO Mode Process And Membrane Bioreactor

In this paper, the process optimization and energy consumption of a wastewater treatment plant(WWTP) in South China were carried out by mathematical model.The operation efficiencies which met classs1 A(GB18918-2002) standard have been studied under normal conditions and special conditions(inflow with landfill leachate).At the same time, the degradation efficiency of reactive dye in MBR was also discussed according to DE-ASM3 model.Through the establishment of WWTP ASM2 D mathematical model, simulation of multi-mode AAO process was carried out. The operation process of multi AAO mode was optimized by changing the operation parameters such as DO value, amount of sludge, the internal reflux ratio and the external reflux ratio. In order to analyze the energy saving potential, mathematical model was established. The results show that the AAO mode was best suit for the optimal operation process. Optimal operating conditions of WWTP can be achieved with 2000 m3·d-1 sludge volume, 50% external reflux ratio and 100% internal reflux ratio. Effluent of CODCr, NH4+-N, TN and other indicators can reach the class1 B of “ Urban Sewage Sreatment Plant Pollutant Emission Standards(GB18918-2002)”. Comparaing the energy consumption before and after the process optimization, 0.84% and 22.58% energy can be saved for DO and internal reflux optimization.The concentration of CODCr, TN and NH4+-N in effluent under three different modified AAO process was simulated by ASM2 D model with different total inflow.The results show that when the total influent volume was 50 thousand m3·d-1, the effluent CODCr and NH4+-N could meet the GB18918-2002 classs1 A standard. In addition, the qualified rate gradually decreased with increasing of inflow. The more influent distribution groups, the better effluent quality can be achieved. Once the influent volume in single set of process was lower than design range of maximum load, the qualified rate of class1 B was reach up to 90%. Under normal conditions(without leachate), three sets of process were needed to ensure the 90% qualified rateof classs1 A standard. Three groups of process operating limit was 100 thousand tons per day.The decoloration rate, CODCr, NH4+-N and TN removal rate of MBR under different dye concentration reached 64.97, 94.70, 76.47 and 59.98%, respectively.Throughout the dye degradation process, the flat membrane resistance was 5~50×1012m-1.The kinetic model of dyes degradation was established by Monod equation, the maximum specific degradation rate(vmax) and substrate saturation constant(KS) were0.073 d-1 and 41.12 mg·L-1.On the basis of ASM3 model, the DE-ASM3 model was established, and the CODCr, NH4+-N and TN in effluent were then simulated. This modified model can effectively simulate the dye degradation in membrane bioreactor process.