Improvement And Optimization Design Of A~2O Process With Multi-Influent In Clod Climate

Along with improvement of wastewater treatment standard in recent years,because of following features: stable operation, lower demand for self-control level and convenient management of maintenance, A~2O process has huge advantage and gradually became most-applied waterwater treatment process in cold area.But traditional A~2O process has the contradiction between phosphorus and nitrogen removal existed in traditional A~2O process. So the traditional A~2O process difficultly obtained good results of denitrification and phosphorus removal meanwhile, The using this process has been limited. For the optimization of the traditional A~2O process, this paper proposed improved A~2O process: multipoint distribution of wastewater and return mixed liquid. The improved process has following features: simple process flow, convenient management of maintenance,multipoint inflow distribution and multipoint mixed liquid distribution, improved efficiency of denitrification and phosphorus removal.In the research by a small test to verify the efficiency of the process technology and traditional A~2O for sewage treatment, through a small test that theory this kind of technology is feasible, with the feasibility of the project implementation,processing efficiency has improved greatly than the traditional process under the same operating conditions, due to the modified A~2O process can accumulate more denitrifying bacteria in the aerobic zone, improve processing efficiency, improved A~2O system to remove the effect of ammonia nitrogen was significantly better than A~2O system; the modified A~2O process can be in the anoxic zone for the growth and reproduction of denitrifying bacteria to provide better conditions, thereby improving the efficiency of denitrification; modified A~2O system for total nitrogen removal efficiency was better than A~2O system.According to actual operation of the improved process in wastewater treatment plant in cold northeast area(treatment scale 50,000 m3/d), achieved following results: TP average removal rate was 89.63%; effluent NH3-N perennial reached less than 5mg/L, and reached less than 1mg/L in the proportional of 83.3%; TN average removal rate was 62.67%, effluent TN average reached 12.76mg/L, maximal TN reached 16.07 mg/L, and reached less than 15mg/L in the proportional of 90%.Operating cost per cubic wastewater reached less than ?0.35 Yuan, power consumption per cubic wasterwater reached less than 0.3kwh. The improved process achieved good treatment effect and obvious energy saving effect.The improved A~2O process is valid process for wastewater treatment in cold area.