Microbial Community And Fouling Potential Of Mixed Liquor In MBR Under The Condition Of Quorum Quenching

Membrane bioreactor(MBR)is defined as one of the most promising biotechnology in water treatment for the stable and efficient performance.However,membrane fouling,especially biofouling,reducing the membrane lifespan and increasing the operation and maintenance costs,get in the way of engineering applications of MBR.Therefore,the mechanism of membrane fouling and corresponding control strategies have become research hotspots.Quorum sensing(QS)is a term used to describe a form of cell-cell communication between microorganisms based on cell-density,which is closely related to biofouling.Interference with QS,that is quorum quenching(QQ),can mitigate membrane biofouling effectively.Though regarded as the basis of sewag e treatment as well as membrane fouling in MBR,microorganism is seldom studied in researches about QQ.This article studed the effect of QQ on MBR by focusing on biofouling,microflora and pollution propensity of activated sludge(AS)in two parallel MBRs.The iflluence of QQ on sludge characteristics,the sewage disposal result and biofouling in MBR was studied.The results indicated that the mixed liquid suspended solids(MLSS),sludge volume index(SVI)and chemical oxygen demand(COD)remove rate showed no remarkable change under the condition of QQ.Besides,biofouling played a key role in membrane fouling in MBRs,which was mitigated by QQ with the elimination of contaminat.The impacts of quorum quenching on microbial community lead to the variation of sewage treatment and sludge characteristics in MBR.16 S rRNA high-throughput sequencing was adopt for the analysis of microbial diversity and community composition in AS and mature cake layer at different periods of membrane fouling.The results showed that microbial community was evolving with the membrane fouling.QQ changed microbial diversity,community structure and succession orientation.The effects of QQ will transform the fouling characteristics of AS in MBR.The degradation of C8-HSL by AS and biofilm formation ability of AS in two MBRs were evaluated in this study.The result indicated that the community and diversity of microorganisms,especially those in connection with QS,were st rongly linked with the pollution characteristics of AS.QQ would increase the biofouling capacity of AS in the short-term,which was not evident after a long period of operation.This study provided more evidence that membrane fouling was regulated by QS.Furthermore,the relationship between QQ and microorganisms in different periods of membrane fouling was comprehensively analysed,as well as the potential impact it may have on membrane fouling.