Tdevelopment Of High-efficiency Biological Purification Technology For Combined Sewer Overflow

With the advancement of technology and the development of society,more and more pollutants are discharged into surface water,the pollution of water environment has become a common problem in the world today.Among them,the combined sewer overflow formed by the overflow of rain and sewage mixed water into rivers and lakes has attracted widespread attention.Although the existing combined sewer overflow treatment technology has a good treatment effect,there are still limitations.Therefore,the search for a new treatment technology and means becomes inevitable.In this paper,an aerated biological filter-high-efficiency nitrification tank process was designed,which proved its feasibility in the treatment of combined sewer overflow.The aerated biological filter-high-efficiency nitrification process unit was operated separately and in series.Processing effect and optimal operating parameters.(1)By performing hydraulic behavioral analysis on reactors operating under different conditions,it is found that with the increase of HRT and the number of reactor cells,the effective volume of the reactor increased significantly,while the increase in the amount of filler filling gradually decreased,but it was effective The volume is still 84?92%.The reactor volume utilization rate under the clear water condition is higher than that of the stable operation reactor.The structural performance of the reactor is excellent,1/Pe is always less than 0.2,and the value of N is 2 to 3 times the actual number of cells.(2)Through RDA analysis of the physical and chemical properties of different fillers and biofilm growth,it is found that the Zeta potential of the filler affects the growth of biomass,and the void ratio affects the growth of dehydrogenase activity,with the increase of zeta potential and porosity the decrease of the void ratio,the reduction in biofilm growth is more advantageous.Combined with the effect of filler on ammonia nitrogen and COD removal load,the volcanic rock has the largest removal load of ammonia nitrogen,which is 34.20g/m~3d,and the ceramsite has the largest removal load of COD,which is 120.75 g/m~3d.(3)By studying the effects of different C/N,HRT,and backwashing conditions on BAF performance,it is found that C/N has little effect on COD removal performance.When C/N is 20,COD removal rate can still reach more than 90%;HRT has a significant effect on COD removal performance.When the HRT is shortened from 2 h to 0.5 h,the COD removal rate is reduced from 99%to 87.67%;When the water is rinsed for 10 minutes,the SS removal rate is the best and the energy consumption is less.(4)By studying the effects of different C/N,HRT and alkalinity conditions on the performance of high-efficiency nitrification tank,it is found that:C/N increased from 2 to 8,the ammonia nitrogen removal rate decreased from 95%to 82%;HRT is shortened from 2 h to 0.5 h,the removal rate of ammonia nitrogen decreased from 95%to 75%;The alkalinity only affects the nitrous oxide and nitrate nitrogen concentration in the system.When the alkalinity of the system increases from 25%to 150%,the effluent nitrous oxide concentration increases and the nitrate nitrogen concentration decreases.(5)The aerated biological filter and the high-efficiency nitrification tank were operated in series to obtain good removal efficiency of COD and ammonia nitrogen.Through the study of HRT conditions,the effluent COD concentration of the reactor meets the"surface water environmental quality standard"(GB3838-2002)Class I standard,the ammonia nitrogen concentration of the effluent meets the Class V standard of the"surface water environmental quality standard"(GB3838-2002),which basically meets the design requirements of the process.