Study On Operation Characteristics Of Integrated Membrane Bioreactor For Domestic Sewage Treatment In A Village

Domestic sewage collection pipe network and treatment facilities are not built in most rural areas of China,and sewage is discharged without treatment,which not only affects environmental sanitation,but even endangers human health.Due to the lagging development of rural economy,the treatment of rural domestic sewage should choose the technology with low investment and operation cost,sustainable environment and acceptable society.With the development of membrane materials and membrane technology,the advantages of membrane bioreactor(MBR)have gradually become prominent.Membrane bioreactor combines biological treatment technology with membrane separation,which has the advantages of high effluent quality,low sludge expansion rate,small occupied area and flexible operation.In this study,an integrated membrane bioreactor(MBR)was designed and constructed.The level meter and time relay were used to control the inflow and outflow of MBR.The experimental water was artificial simulated domestic sewage.Different materials of membrane were selected to explore the operation effect of membrane bioreactor in rural domestic sewage treatment and the flux change of membrane module.The optimal operation condition of membrane bioreactor was obtained from the perspective of alleviating membrane pollution.The operation difference between organic membrane and ceramic membrane was compared,the cause of membrane fouling was analyzed,the membrane fouling model was fitted,and the appropriate cleaning method of membrane module was selected.The results showed that the membrane bioreactor could significantly alleviate the membrane fouling under the conditions of subcritical membrane flux,optimal aeration rate and optimal pump stop ratio.The results showed that the removal rates of COD,ammonia nitrogen and total phosphorus by organic membrane were 88%,95% and 62%,respectively;the removal rates of COD,ammonia nitrogen and total phosphorus by ceramic membrane were 90%,98% and 43%,respectively;the turbidity of organic membrane effluent was0.4～0.7 NTU,and that of ceramic membrane was 0.1～0.4 NTU.The effluent quality is better than that of municipal wastewater reuse,urban miscellaneous water quality standard and farmland irrigation water quality standard.The membrane fouling mechanism was analyzed and the filter cake layer model was well correlated.It was proved that the filter cake layer was mainly blocked.Comparing the differences of different cleaning methods,the combination of physical and 0.3% hydrogen peroxide reagent was used to clean the membrane module.Compared with the performance of organic membrane bioreactor and ceramic membrane bioreactor,the stable operation flux of ceramic membrane is larger than that of organic membrane,and the effective area of ceramic membrane module is small under the same treatment water.Under the optimal operating conditions,the effluent quality of ceramic membrane is better than that of organic membrane,the effluent turbidity is small,and the filtration performance is good.