Operation Optimization Of AAO-MBR Process Based On Biowin Simulation

As the national standards for wastewater treatment are increasing,Shenzhen requires that the effluent pollutants of the sewage treatment plant be upgraded to meet the surface water "quasi-IV" standard.The AAO-MBR process is widely used in standard upgrading projects due to its small footprint and excellent effluent water quality.However,its process is still to be studied.The traditional "small test-pilot test-application" research method is time-consuming and expensive,but mathematical models can guide experimental design and operation management,and improve research efficiency.This research is based on model simulation and small experiment,using Biowin software to carry out the AAO-MBR process simulation,to study the effect of related parameters on process operation,to propose a process operation optimization plan for AAO-MBR wastewater treatment plant.According to the actual operation process of the AAO-MBR process sewage plant,a simulation model was built on the Biowin software platform,and the parameters of the carbon,nitrogen and phosphorus influent components were measured,in which the rapidly degradable COD accounted for 21% of the total COD,and ammonia nitrogen accounted for the TKN 74%,dissolved phosphorus accounted for 73% of the total phosphorus.The sensitivity analysis of the model was carried out,and six kinetic parameters and stoichiometric parameters that had a great influence on the results were screened out: ammonia oxidizing bacteria maximum unit growth rate,heterotrophic bacteria aerobic decay rate,denite N₂ producers in heterotrophic bacteria denitrification,Phosphorus in endogenous residues,yield（aerobic）,yield（anoxic）.After correction,the relative error between the simulated value and the measured value is controlled at about 10%,indicating that the model can simulate the AAO-MBR process accurately.Based on simulation research,a small test verification experiment was carried out.A single factor analysis method was used to study the effect of related parameters on the AAO-MBR process operation.The results show that the model can predict the process operation well.The backflow ratio,backflow method and staged influent have little effect on the water quality of the system effluent COD and NH₄⁺-N,and have a certain effect on the system effluent TN and TP.When the reflux ratio is reduced from 400% to 300%,increase the nitrate liquid reflux（The reflux ratio is 200% and the internal reflux ratio is 100%）and the staged inflow ratio is 1:1,the system’s nitrogen and phosphorus removal efficiency is improved,and it can reach the surface water "quasi-IV" standard.Based on the small experiment and the actual operation data of the wastewater treatment plant,after comprehensive analysis of various factors,the process optimization plan for the wastewater treatment plant was proposed and model simulation was carried out: the staged inflow ratio was set to 1:1,the sludge reflux ratio was set to 200%,and the nitrification liquid reflux was set to 100%.The concentration of effluent COD,NH₄⁺-N,TN,TP is divided into 18.22 mg/L,0.14 mg/L,6.60 mg/L,0.21 mg/L,all of which can meet the surface water "quasi-IV" standard,and TN’s Removal efficiency increased by 21%.After the process optimization,the concentration of the sludge in the membrane pool is in the range of 8000 ～ 10000 mg/L,which is in a range that has little effect on the membrane pollution.Take measures of hydraulic cleaning,acid cleaning and alkaline cleaning in sequence,and the membrane flux recovery degree reaches 98%.