The Effect Of Anaerobic Quorum Quenching Mechanism On Membrane Biofouling Control And Methane Production In AnMBR

The anaerobic membrane bioreactor(AnMBR)process has a great prospect in the field of water treatment because it integrates the advantages of efficient treatment of pollutants and recycling of renewable resources.It can treat various types of waste streams and recycle the chemical energy of organic carbon into biological energy,hydrogen energy and electric energy.However,the application of AnMBR process still faces many challenges that need to be addressed,especially serious biofilm pollution and low methane productivity in biogas recovery.After continuous exploration of biofilm growth mechanism,it has been found that N-acyl homoserine lactones(AHLs)mediated quorum sensing mechanism happens commonly in wastewater treatment systems.Based on quorum quenching(QQ)technology,the quorum sensing signals in water treatment process can be interfered to effectively control biofilm pollution.Among the available QQ strategies,using biostimulants to enrich and expand a large number of functional QQ bacteria is the most potential strategy against membrane fouling.The biostimulants for enrichment of activated QQ bacteria are usually various types of AHLs,however,the chemical extraction process of AHLs is complicated,the price of AHLs is expensive and not available for large-scale development.On the contrary,gamma-caprolactone(GCL)has been reported as a quorum quenching biological stimulant and has received much attention.Similarly,the functional properties of absolutely anaerobic QQ strains have not been studied,although a small number of QQ consortiums have successfully delayed AnMBRs biological contamination.Therefore,this paper presents firstly the absolutely anaerobic QQ bacteria enriched by GCL and AHLs to delay and control the biological fouling process of AnMBRs.In addition to exploring the delaying effect of QQ bacteria on biofouling pollution in AnMBRs,this study introduced biological stimulants directly into anaerobic sludge to make it condensing and retaining methanogenic bacteria system in the sludge base besides QQ functional bacteria.In the subculture of bacteria,dual-function QQ bacteria that can control membrane pollution and enhance methane productivity were finally obtained.In order to directly compare the differences between GCL and AHLs as inducers for QQ bacteria enrichment,this study publishes the first multi-dimensional systematic evaluation of the facultative and absolutely anaerobic QQ consortiums mediated by GCL and AHLs.It was found that acyl bonds in the structure of AHLs introduced additional ammonia nitrogen into the QQ bacteria culture.The high ammonia nitrogen inhibited the methanogenic capacity of anaerobic QQ bacteria and triggered denitrification in the facultative environment.The nitrogen oxides produced during the process were toxic to a large number of anaerobic bacteria,expecially methanogenic bacteria.The results showed that the QQ mixture enriched with AHLs had little effect on enhancing methane productivity.It is worth noting that due to its special structure,the absolutely anaerobic QQ bacteria mediated by GCL avoid the above defects and successfully integrate multi-functional bacteria that control membrane pollution and enhance methanogenic production.Besides its internal quorum sensing quenching mechanism has efficient quorum sensing signal interruption ability,A methanogenic bacteria system with Mathanosaeta and Mathanobacterium as the dominant species that is conducive to the methane metabolism of AnMBR has been protected and cultivated,which has significantly enhanced the productivity of AnMBR.