Experimental Research On Hydrlysis Precipitation And Two-Stage Biological Filter For Urban Sewage Treatment And Project Commissioning

More and more urban sewage was discharged as the rapid development of urbanization in China. It was a challenge for the conventional activated sludge process which can not meet the stringent environment protection requirements. Therefore, improvement and innovation of urban sewage treatment technology had practical significance and broad application prospect. Biological aerated filter?BAF? was wildly adopted for domestic urban sewage treatment. However, effluent quality of BAF could not meet the standard A of “Pollutant discharge standard of urban sewage plant?GB18918-2002?”. Based on one engineering example of urban sewage treatment, process of hydrolysis precipitation and predenitrification biological aerated filter?HP-PBAF? was investigated to improve removal efficiency of BAF. Rmoval efficiency of hydrolysis precipitation?HP?, denitrification biological aerated filter?DN? and carbonization and nitrification biological aerated filter?CN? were investigated in detail.Effect of different conditions on the operation of HP, DN and CN were analyzed in laboratory scale. The results showed that removal efficiency of HP was siginificantly affected by the height of suspended sludge layer. Moreover, CN and DN removal efficiency were aslo investigated. The results showed that temperature in the range of 10-25?, dissolved oxygen in the range of 5-7mg/L, reflux ratio of 130%, the effluent of COD, NH₄⁺-N and total nitrogen of on average were 38.56mg/L, 4.4mg/L and 13.5mg/L, respectively. Chemical phosphorus removal was adopted in the paper. FeCl₃?40%? with the concentration of 35mg/L was added into CN. The results showed that the average removal efficiency of total phosphorus was above 80%.The optimum operation conditions in laboratory scale was used to guide real urban sewage treatment project. According to the situation of real ueban sewage treatment project, the problems of SS removal, head loss and filter loss were effectively solved during commissioning. During commissioning, removal efficiency of COD, NH_3-N and total nitrogen were more than 60.0%, 81.5% and83.0%, respectively. The effluent of COD, NH_3-N and total nitrogen on average were 15.1mg/L, 5.0mg/L and 41.3mg/L, respectively. When the operation of HP-PBAF reached design value, the effluent COD, BOD₅, TN, NH_3-N, TP and SS could meet the standard A of “Pollutant discharge standard of urban sewage plant?GB18918-2002?”...