Experimental Study On Optimizing The Treatment Of Urban Domestic Sewage By Cyclic Batch Mud-film Composite Biological Filter

Cyclic batch mud-film composite biological filter is a new type of urban sewage treatment process that combines activated sludge method and biofilm method.In the early stage of the research group,the process of film hanging and initial operation was studied.This test optimizes the process by adjusting the process operation mode and studying the enhanced nitrogen and phosphorus removal test plan,and conducts a year-round hydrological test study on the equipment to provide test basis for subsequent practical engineering applications.Adjust the inflow method in the aeration period to the inflow period,and use the inflow top support outlet constant water level outflow method,which can not only reduce the head loss of about 1m,the results showed that when the operation cycle was set as 45min in the aeration stage,15min in the precipitation stage and 30min in the inlet and outlet stage,the operation effect of the process was more stable.Reflux method have a greater influence on the effect of the process operation.The experiment found that the effects of nitrogen and phosphorus removal in the process of aeration period?return of nitrification liquid+sludge return?,precipitation period?no return flow?,and water inflow and exit period?sludge return flow?are relatively good,the average concentrations of NH₄⁺-N,TN and TP in the effluent were 0.252mg/L,6.56mg/L and 0.4mg/L,respectively.Based on the above optimization results,after 30 days of stable operation of the equipment,the test results show that the overall average effluent can reach quasi-IV water quality standards,but due to the large fluctuations in the daily influent,the TN and TP concentrations in the effluent increase part of the time,and the compliance rate is only 66.7%.The effect of adding suspension filler in the first-stage anoxic tank on the denitrification efficiency of the process was studied,and the optimal filling ratio of the anoxic tank filler was determined.The results showed that the suspended filler could significantly improve the stability of denitrifying bacteria in the anoxic tank.When the filling ratio was 20%,the denitrification efficiency was the most obvious,the removal rate of TN increased to 64.8%,and the average TN of effluent was 8.32mg/L.Further increasing the filling ratio to 30%will affect the nitrification efficiency of the second stage,resulting in the reduction of the denitrification efficiency.In view of the situation where the TN concentration of the influent is too high??30mg/L?,consider using the flexible and adjustable characteristics of the process to increase the idle return period.When the operating cycle is 120min,the nitrogen removal efficiency is increased to 72.5%,and the effluent TN completely meets the quasi-?water quality standard.The SRT of the mud film composite process can be adjusted in a larger space.Shortening SRT can improve phosphorus removal efficiency and stability,the study shows that it is most appropriate to set the SRT to 10d on the basis of ensuring nitrogen removal efficiency,the TP concentration of the process effluent is 0.26mg/L,and the TP removal rate is 95.3%.When the influent TP exceeds 4.0mg/L,it cannot reach the quasi-IV water quality standard by 100%only by biological phosphorus removal,so it is necessary to test and investigate the effect of adding flocculant to strengthen the phosphorus removal by this process.The test results show that the effect of flocculant PAFC on dephosphorization is obvious,and the dosage of PAFC is 20mg/L.During the test,the average influent TP was 4.7mg/L and the effluent TP concentration was 0.16 mg/L.When the dosage was further increased to 30 mg/L,the process effluent SS slightly increased.In the dry season?1-2 months and 10-12 months?,the HRT was set to 10h,and the20mg/L of PAFC were added;during the rainy season?3-9months?,the HRT was set to 7.5h,and no chemicals are added.The annual hydrological test results show that the annual effluent of the process can stably reach the quasi-IV water quality standard.Compared with the A²/O+SF process of the water plant,this process has better treatment effect and higher processing capacity.The volume load of each pollutant in the process is more than 1.5 times that of the water plant,and the operating cost is 0.244 yuan/m³,which can significantly reduce the cost of sewage treatment by about 30%.