Study On AAO-HMBR Process For Treatment Of Domestic Wastewater And Membrane Fouling

Membrane bioreactor(MBR),as a new water treatment technology,has many irreplaceable advantages.The separation of SRT(sludge residence time)and HRT(hydraulic residence time),which cannot be realized by the traditional activated sludge process,can greatly improve the sludge concentration.In addition,the MBR technology has the advantages of small footprint and high denitrification efficiency,so it is widely used in water treatment.However,in the process of MBR operation,membrane pollution caused by the interaction of organics,colloids and sludge flocculants in sewage with the membrane surface will lead to the decrease of water discharge and the increase of operation cost,and membrane pollution seriously impedes the progress of MBR technology.Examines the AAO-the MBR and the test system after adding the filler of AAO HMBR system under the condition of the same operation efficiency and film processing sewage pollution condition,mainly has carried on the AAO-MBR reactor system startup,AAO-HMBR reactor operating conditions optimization,two under the steady operation of reactor for sewage treatment efficiency and membrane fouling status contrast and AAO membrane fouling characteristics of HMBR research.The main conclusions of the experiment are as follows:(1)The two reactors have relatively ideal removal rates of COD,ammonia nitrogen and TN in domestic sewage.Due to the long SRT,the removal rates of both reactors are not very ideal for TP.The removal of TP by AAO-HMBR was higher than that by AAO-MBR,but not by much.The removal rates of COD,ammonia nitrogen,TN and TP in the reactor increased from 92.71%,95.08%,41.87% and 64.13% to 96.06%,98.4%,59.1% and 72.2%,respectively.(2)The addition of packing improved the membrane contamination degree of aao-mbr system and the recoverability of membrane components.When TMP increased to 26 kPa for the first time,HMBR system ran for 20 days,while MBR system only ran for 13 days.After running for the same time,the membrane of aao-mbr system was observed under scanning electron microscope,and there was clearly visible contaminant attachment,but HMBR only had a small amount of adhesion,and the membrane surface pollution was lower.After running for a period of time,the infrared spectrum analysis of the filter cake layer on the outer surface of aao-hmbr system membrane module shows that the main pollutants on the membrane surface are proteins and polysaccharides.(3)The determination of EPS extracted from the sludge samples of each part of aao-hmbr reactor revealed that the total EPS of mixed solution,biofilm and membrane filter cake sludge were 10.04mg/L,27.3mg/L and 20.02mg/L,respectively,with the highest content of EPS in biofilm sludge.Biofilm sludge has the highest EPS content,because the formation of biofilm on the filler can reduce the EPS content in the mixture.The s-eps/b-eps of mixed sludge was greater than the membrane cake layer,because the fluidity of mixed sludge was greater than the membrane cake layer.(4)The effects of the changes of HRT,aeration amount in the aerobic zone,mixed liquid refluxion ratio and water pumping/stopping ratio on the reactor operation effect and membrane fouling rate were studied.The optimum HRT for the operation of aao-hmbr was obtained to be 10 h,and the removal rates of COD,ammonia nitrogen,TN and TP in the reactor were 97.67%,97.33%,55.79% and 67.92%,respectively.The optimal aeration strength is 0.4L/min,and the removal rates of ammonia nitrogen,TN,COD,TP97.11%,58.26%,96.63% and 72.13% can be achieved in the reactor respectively.At this time,the removal rates of COD,ammonia nitrogen,TN and TP in the reactor were 150%,96.41%,98.15% and 58.26%,respectively.The HRT,aeration volume and pumping/stopping time in the aerobic zone were 12 h,0.6l /min and 7:3min,respectively,which were most conducive to slowing down the occurrence of membrane pollution in the reactor.