Research On Upgrading Technology Of Wastewater Treatment Plant In AAO Oxidation Ditch Process In Plateau Area

In recent years,with the continuous improvement of people's living environment requirements,higher requirements are imposed on the discharge standards of sewage treatment in China.A large number of sewage treatment facilities of urban sewage treatment plants need to be further upgraded.The plateau region in the western part of China is in a low temperature state all the year round,and the sewage treatment plant has a poor operation effect.The western plateau region is located at the source of Sanjiang River,and local sewage treatment plays an important role.Therefore,this project is aimed at the poor sewage treatment performance in the western alpine region,combined with the optimization of operation and renovation methods to improve its sewage treatment effect and enable it to operate stably throughout the year.The main problems in the sewage treatment plant are low influent concentration,low microbial activity and poor sewage treatment efficiency;nitrification is significantly affected by temperature in winter;TN and TP removal rates are generally low throughout the year,C/N and C/P are 4,58.Secondly,the sewage plant has problems such as excessive aeration and single control technology.It is difficult to raise the standard to the class?standard for surface water on the basis of the original process.In view of the problems existing in the sewage treatment plant,engineering measures such as adding a filler in an aerobic tank,setting up a special intercepting facility,adding low-temperature and high-efficiency microbial agents and microbial active agents,regulating the volume of functional areas,and optimizing DO concentration and anoxic in aerobic zone are mainly used.The operating parameters such as point water inflow,sludge reflux,and mixture reflux ratio are differentiated to improve the removal efficiency of COD,nitrogen,and phosphorus,and to ensure stable discharge of the effluent.The effects of the average DO concentration in the aerobic zone,the influent of the anoxic zone,the sludge reflux ratio?R?,and the reflux ratio of the mixture?r?on the nitrogen and phosphorus removal performance of the AAO oxidation ditch process were systematically studied.The average DO concentration of aerobic zone,point water inflow,R and r are 1.5mg/L,30%,80%,300%,the sewage treatment effect is the best,the average effluent COD,NH₃-N,TN,TP concentration are 21.77mg/L,0.54mg/L,12.96mg/L,0.46mg/L,and finally the TP concentration is controlled to 0.3mg/L with advanced treatment.After engineering and parameter optimization,the sewage treatment plant can produce water.Stable to reach class?standard for surface water.In order to further investigate the lifting space of TN removal effect,an aerobic/anoxic transition zone was set up in the aerobic zone,and the AAO process was switched to the AAO-AO process.The effects of different flow distribution ratios on wastewater treatment were studied.The experimental results show that when the flow distribution ratio is 4:3:3,the sewage treatment effect is the best.The average effluent COD,NH₃-N,TN and TP concentrations are 19.70 mg/L,0.64mg/L,10.30mg/L,0.52mg/L,which verified that the multi-stage AO staged water injection process has a significant effect on improving biological nitrogen removal performance.The effluent TP concentration increased slightly,but the change was not obvious.Class?standard for surface water can be stably achieved without increasing the dosage.After engineering transformation and parameter optimization,the sewage plant can save about320,000 operating costs per year.