Influence Of SRT On HMBR Operation Efficiency And Membrane Fouling Principle

Membrane bioreactor(MBR)is a new type of wastewater treatment process which has been developing rapidly recently.This experiment adopts a new technology of composite membrane bioreactor combining the moving bed biochemical reactor and membrane separation technology.The experiment mainly examines the effect of SRT on the efficiency of membrane fouling in the treatment of pollutants in domestic sewage by HMBR.The research on the mechanism of the influence of SRT on membrane fouling has been studied.This has important guiding significance for the practical application of HMBR technology into the future.In this experiment,a total of four HMBR units with a design capacity of 2.4m3/d were set up and the reactor was filled with polyolefin fillers.The test examined the difference in performance of the HMBR process and the conventional activated sludge process for domestic sewage treatment.The results showed that the removal rates of CODcr,NH3-N,TP,and turbidity by HMBR were 91.4%,93.2%,84.8%,and 99.5%,respectively,which were increased by 3.4%,3.2%,4.4%,and 7.2%,respectively,compared with the activated sludge process.However,the removal rate of TN was only 55.7% lower than the activated sludge process by 9.1%.During the entire test period,all the effluent indexes of HMBR met the pollutant discharge standards of urban sewage treatment plants(GB18918-2002).At the same time,the effects of SRT on the treatment efficiency and EPS of HMBR process were investigated.The results showed that the removal rates of CODcr,NH3-N,TN and turbidity of HMBR increased first and then decreased with the extension of SRT.The HMBR operation was performed when the SRT was 20 days.With the best efficiency,the removal efficiency of CODcr,NH3-N,TN and turbidity in the sewage is the best.The effluent meets the pollutant discharge standard of the urban wastewater treatment plant(GB18918-2002).However,the removal rate of TP by HMBR decreased with the increase of SRT.When SRT was 10 d,the removal rate of TP was the best.The removal rate was 82.1%.When SRT was 20 d,the growth trend of TMP was the slowest,that is,the HMBR system was in SRT.For20 days,the anti-pollution ability is the strongest.In summary,it can be concluded that when the SRT of the HMBR equipment is controlled at 20 days,the system has the best removal efficiency of pollutants in the sewage,and has the strongest anti-pollution ability.It can be considered that SRT=20d is the best operating condition of the HMBR equipment..With the extension of SRT,the total amount of EPS decreased first and then increased.Among them,S-EPS and LB-EPS changed more obviously with SRT,and the content was the least when SRT was 20 days.SRT continued to increase,and S-EPS increased slowly.The LB-EPS will grow rapidly and the TB-EPS will not change much.This is mainly because different SRTs will cause different sludge load in the HMBR reactor,which will affect the EPS.The EPS content in the reactor is 20 days when the SRT is 20 days.At the lowest,the sludge load is at its best.Finally,the experiment studied the mechanism of SRT affecting membrane fouling.It was found that changes in SRT changed the content of S-EPS and LB-EPS first.Subsequent changes in the content of S-EPS and LB-EPS affected membrane pore resistance Rp.And filter cake resistance Rc size,thus changing the degree of membrane fouling of HMBR,which LB-EPS and S-EPS by changing the sludge flocculation and precipitation and then affect the cake resistance Rc,the less its content The stronger the sludge flocculation and sedimentation,the greater the cake resistance.