Research On The Construction Of Quorum Quenching Based On Biological Stimulation And The Control Of Membrane Fouling

Membrane bioreactor(MBR)has been widely used in urban sewage treatment due to its excellent treatment efficiency,but the Membrane fouling problem in MBR has not been properly solved,which has become a technical bottleneck to be broken through.Membrane fouling is closely related to quorum sensing of microorganisms.The method of amplifying native functional bacteria through biological stimulation is simple and flexible,and can play the function of functional bacteria more effectively.Biostimulation strategy has been widely used in the field of biological wastewater treatment,but there are few reports on the use of biostimulation to regulate the microorganism quorum sensing in MBR and to control biological pollution.Therefore,in order to in situ and effectively solve the problem of MBR in biological pollution,this article explores in situ amplification by means of biological stimulation local signal molecular degradation function of bacteria in the MBR,and further to functional bacteria immobilized,and information exchange between quenching microbes,inhibition of quorum sensing,and thus achieve the goal of membrane biological pollution control.In this study,five stimulants,Gamma-caprolactone,Gamma-heptanolactone,xylonic acid γ-lactone,carbonamide,and acetamide,were selected by screening chemical substances similar in structure to signal molecules(Acyl homoserine lactone,AHL).In situ enriched clusters were sterilized by induction and the ability to degrade signal molecules was investigated.The results show that the five stimulating enrichment bacteria all have good degradation efficiency,and the gamma-caprolactone enrichment bacteria have the best effect.The short-chain AHL is more difficult to be degraded than the long-chain AHL.Through the analysis of the microbial community of the enriched bacteria liquid,it was found that the main function of microbial quorum sensing quenching was Gordonia.Further immobilization measures were taken to enrich the bacteria,and it was found that the immobilization of QQ(Quorum quenching,QQ)bacteria may have a certain mass transfer limitation.The degradation efficiency of QQ spheres on signal molecules is lower than that of QQ bacteria.Five stimulants Among the enriched bacteria QQ balls,GCL-stimulated enriched bacteria QQ balls have the best degradation effect on signal molecules.By analyzing the degradation products,it was found that the lactone ring of the signal molecule was opened and degraded into acyl homoserine(C8-HS).Three kinds of QQ balls,Gamma--caprolactone,xylonic acid gamma lactone,and carbonamide,which stimulate the enrichment of bacteria,are put into MBR.The QQ balls can reduce the concentration of C8-HSL in the reactor and inhibit the secretion of EPS.It slows down the adhesion of microorganisms on the surface of the MBR membrane,prolongs the cycle of membrane fouling,and achieves the effect of controlling membrane fouling.Among them,the effect of enriching QQ balls withγ-caprolactone as a stimulant is the best.At the same time,the control of membrane fouling through microbial quorum sensing quenching technology did not affect the removal of COD and ammonia nitrogen by MBR.