Study On The Decentralized Treatment Of Sewage By MBR

In recent years,with the in-depth development of the construction of new socialist countryside,great changes have taken place in rural infrastructure and environment.At the same time,the problem that rural domestic sewage can not be properly treated is becoming more and more serious.Rural domestic sewage is a kind of intermittent discharge.Its water quality and quantity fluctuate greatly,and the concentration of organic matter is relatively high.It also contains high components of human and animal manure,especially the content of nitrogen and phosphorus.Because the sewage is directly discharged into the water body for a long time,and the environmental capacity is very limited,resulting in the water body black odor,eutrophication is very serious,so the technical demand of rural sewage decentralized treatment is urgent.At present,the commonly used rural sewage decentralized treatment technologies include artificial wetland,oxidation pond and other ecological treatment technologies.However,these processes have complex maintenance and management,low treatment efficiency and other problems,so new and stable technologies are urgently needed.As a new technology,MBR has obvious advantages in sewage treatment,such as high treatment efficiency,stable effluent,strong impact load resistance,and low sludge output.However,due to the late start of MBR technology in my country,early limited by the price and technical difficulty of membrane materials,the process is rarely used in rural sewage treatment.Nowadays,with the development of the combination of membrane materials and sewage technology,the cost of membrane components has been greatly reduced,and the equipment has gradually been automatically controlled.The advantages of the MBR process are more prominent,and it is suitable for rural sewage decentralized treatment.Therefore,this paper studies the application of MBR technology in rural decentralized sewage treatment to promote the development of rural sewage treatment technology.Based on the MBR process,the experiment discussed the optimal working conditions of aeration intensity,mixed liquid reflux ratio,sludge concentration,and PAC dosage.Through dynamic experimental research on the treatment of sewage,the system's COD under different working conditions was investigated,Ammonia nitrogen,total nitrogen,total phosphorus removal effect,membrane cleaning technology to control membrane pollution and the feasibility of MBR process application,the main research results are as follows:After the system commissioning and operation are stable and the removal effect meets the design requirements,when the aeration intensity is controlled at 500 L/m~2h,the removal rate of COD and ammonia nitrogen reaches more than 90%,and the removal effect of ammonia nitrogen is the best;the reflux ratio of the mixed liquid is controlled at 200%,the removal rate of TN reaches more than 70%,the best removal effect;when the sludge concentration is controlled at 6000 mg/L,the removal rate of COD reaches more than 90%,the removal rate of ammonia nitrogen and total nitrogen reaches more than 70%,and COD And the total nitrogen removal effect is the best;when the system PAC dosage is controlled at 20 mg/L,it can improve the removal effect of COD,ammonia nitrogen and TP to a certain extent.At the same time,the cleaning method of acid/alkali combination(30 min Na OH0.5%immersion rinse and 30 min 0.5%HCl immersion rinse)is adopted,and the membrane flux recovery effect can reach about 95%or more.Combined with the experimental research results,a pilot study was conducted on the feasibility of the MBR process in the decentralized treatment of rural sewage.The results show that the process has a good removal effect on pollutants in sewage,and the average COD in the effluent is about 30 mg/L Ammonia nitrogen is about 1.50 mg/L,TN is about8.8 mg/L,TP is about 0.29 mg/L,which can ensure that the effluent quality of the system basically meets the surface water category IV of"Surface Water Environmental Quality Standard"(GB3838-2002)Claim.In addition,under the best working conditions,the TMP of the membrane needs to be increased to the design limit in about 25 days,and then the acid/alkali combined cleaning method can effectively restore the permeability of the membrane.