Experimental Study On Nitrogen Removal Performance Of Improved AB Process In Municipal Sewage Treatment

With the continuous improvement of discharge standards for urban sewage treatment in the country,the transformation process to enhance the denitrification capacity has become an important issue facing urban sewage treatment plants.This article takes the effluent from the primary settling tank of a sewage treatment plant in Baoding as the treatment object,designs and constructs the phoredox process test device,and adds a pre-aeration tank and an intermediate settling tank on this basis to form an improved AB process test device.By studying the effects of three different factors on the DO concentration,nitrate reflux ratio and sludge reflux ratio of the aeration tank on the nitrogen removal effect of the phoredox process unit and the improved AB process B section,as well as the two sets of test equipment and the COD in each reaction tank of the sewage plant And the removal rule of N,draws the following conclusions:In the two experimental devices and the operation process of the sewage plant,the DO concentration,the nitrate reflux ratio and the sludge reflux ratio of the aeration tank had the smallest impact on the removal of NH₃-N,and had a greater impact on the removal of TN.As the DO concentration in the aeration tank and the reflux ratio of the nitrification liquid increase,the removal rate of TN increases first and then decreases.The lower DO concentration and the proper reflux ratio of the nitrification liquid ensure the growth environment of denitrifying bacteria in the anoxic tank.It is more conducive to the improvement of the denitrification effect,but the lower DO concentration will adversely affect the removal of COD;the higher sludge reflux ratio of the reaction tank ensures the microbial content and activity therein,and improves the denitrification effect and guarantees To remove COD in sewage.The two process units achieve the best working conditions when the DO concentration is 1.5².0 mg/L,the nitrification liquid reflux is 300%,and the sludge reflux ratio is 100%.At this time,the average removal rate of the improved AB process TN is3 times that of the phoredox process.The effluent TN is stable below 5 mg/L,which meets the key control area standards in the"Water Discharge Standard for Daqing River Basin"?DB13/2795-2018?.Under the optimal working conditions,when entering the first biochemical reaction tank of the two experimental devices and the actual operation process of the sewage treatment plant from the influent,there is a direct dilution effect on the pollutant concentration in the raw water,and the phoredox process has the most obvious dilution effect At the same time,the anaerobic tank and the anoxic tank of the two experimental processes still mix to a certain extent;COD,NH₃-N and TN pass through the phoredox process unit and the anaerobic tank,anoxic tank and aeration tank in the sewage treatment plant The removal effect of more than90%has been completed.The improved AB process A section has the most obvious removal effect on COD,and the removal effect of NH₃-N and TN is not ideal.The first three reaction tanks in section B have COD and N in the sedimentation tank.Removal rate of more than95%.The two test devices and the anoxic tank and terminal aeration tank at the rear of the sewage plant further ensure the stability of the effluent index;the improved AB process has better overall pollutant removal effect than the other two processes.Efficiency,and the effluent index is stable.This study provides data support for parameter optimization and pollutant variation along the way to improve the AB process,and has certain guiding significance for the process transformation of wastewater treatment plants.