Study On The Improvement Of Denitrification And Phosphorus Removal In A/O-MBR With Electrocoagulation

A/O-MBR is widely used in treating municipal sewage and industrial wastewater. This technology combine A/O activated sludge process with technology of membrane separation. Membrane module is immersed in the aerobic pool for solid-liquid separation. Denitrification and phosphorus release are conducted in the anaerobic pool, removal of organics, oxidation of nitrogen organics, nitrification of ammonia nitrogen and absorption of phosphorus are conducted in the aerobic pool. The treating efficiency and membrane pollution are the A/O-MBR’s confronting problems.In this study, a conventional A/O-MBR reactor and an electrocoagulation A/O-MBR reactor were used to treat simulated domestic wastewater to study the reinforcement of the electrocoagulation to the removal efficiency of nitrogen and phosphorus, the slowdown in the membrane fouling. At the same time, adjust the operational parameters like sludge return ratio, hydraulic retention time, C/N and so on to determine the best process operating conditions. At the end of the study, this electro-coagulation A/O-MBR process was used to treat the actual livestock wastewater to see the process’s efficiency and stability of the high TN and TP wastewater.The research results showed that the effiency of the electrocoagulation A/O-MBR is more stable than the conventional A/O-MBR. When the reflux ratio was 100%, the electrocoagulation A/O-MBR’s NH4+-N, TN, TP removal rate were 96.88%, 71.34% and 71.41%,7.26%,6.16% and 66.37% higher than the conventional one. As the hydraulic retention time decreased, the electrocoagulation A/O-MBR kept better denitrification and phosphorus removal effect. When the hydraulic retention time was 4h, the electrocoagulation A/O-MBR’s NH4+-N, TN, TP removal rate were 90.94%, 73.05% and 72.98%,20.25%,10.55% and 58.65% higher than the conventional A/O-MBR. When C/N decreased to 6, the electrocoagulation A/O-MBR’s NH4+-N, TN, TP removal rate were 96.52%,70.4% and 52,42%,22.46%,13.72% and 45.62% higher than the conventional A/O-MBR.Under the optimal operating conditions (reflux ratio was 200%, hydraulic retention time was 8h, C/N was 10, plate voltage was 2V), The electrocoagulation membrane reactor’s removal rate of COD, NH4+-N, TN, TP were 6.45%,2.8%,3.38%, 1.91%; the conventional A/O-MBR reactor’s removal rate of COD, NH4+-N, TN, TP were 96.08%,83.04%,60.21%,17.67%; the electrocoagulation A/O-MBR reactor’s removal rate of COD, NH4+-N, TN, TP were 99.14%,97.37%,73.7%,82.94%, the conventional A/O-MBR. The electrocoagulation A/O-MBR had the highest efficiency.The electrocoagulation A/O-MBR was also used to treat the high concentrations of nitrogen and phosphorus of livestock and poultry breeding wastewater. After the system was stable, the average removal rate of COD, NH4+-N, TN, TP were 86.97%, 94.31%,87.96% and 70.97%, and results showed that this electrocoagulation A/O-MBR had good treatment effect of livestock and poultry breeding wastewater.