The Study On Simultaneous Nitrification And Denitrification In Membrane Bioreactor(MBR)

The submerged membrane bioreactor (MBR), a combined process of biological treatment with advanced membrane separation, is a new technology for wastewater treatment and reuse. By experiment in a orthogonal design, Process conditions of treatingsewage, as well as relevant process planning were investigated. optimizational process conditions of MBRtreating sewage were made certain in this dissertation.The following results have been obtained:By a long-term running test, steady operational performance of MBR treatingdomestic wastewater was discussed in optimized conditions. During the whole running, the results of removing organics was steady, COD remained below 30mg/L, and other index could reach criteria of reuse water. Although the system had great resistance to impact load, so pollutant concentration need control. Controlling maximum pollutant concentration was analyzed from the theory for the first time. Design discipline, way and procedure were raised in submerged MBR, as well as cooperation of various powers in optimized conditions. Running energy consumption and fixed investment were also evaluated.(1) The experimental results in Activated Sludge System and MBR showed that DO is a limiting factor to Simultaneous nitrification and denitrification(SND), C/N is a key factor to Simultaneous nitrification and denitrification(SND),and pH is an important factor to Simultaneous nitrification and denitrification(SND).According to the experimental results, The efficiency of simultaneous nitrification and denitrification is the best when DO concentration is 0.8mg/L-1.0 mg/L and pH is neutral to alkalescent. With reduction of COD/TN,the TN removal efficiency becomes lower. But the TN removal efficiency increasing with enhancing F/M.(2) The iduence mechanism on the efficiency of nitrogen by SND in Activated Sludge System and MBR was discussed. The effects of different factors on the efficiency of nitrogen by SND in Activated Sludge System and MBR could be explained by the theory which including microscopic environment theory and microbiology theory.(3) According to the experimental results, the influence mechanism which DO and C/N affect on SND is consistent in Activated Sludge System and MBR.(4) F/M is another key factor impacting on the simultaneous nitrification and denitrification(SND).For the best efficiency of simultaneous nitrification and denitrification, F/M is not same in the different DO concentration. In this experiment,F/M is 0.15～0.36KgCOD/KgMLSSd for best efficiency of simultaneous nitrification and denitrification in MBR when DO concentration is 0.8mg/L.