Enhancement Construction And Mechanism Of Membrane Aerated Biofilm Reactor-based Wastewater Treatment System

Membrane-aerated biofilm reactor（MABR）is an emerging and efficient biofilm-based process for wastewater treatment.MABR is widely used in various wastewater treatment due to the high oxygen transfer efficiency,superior pollutants removal and minimal cost of sludge treatment.However,the wider application of MABR is limited by the lack of enough biofilm biomass,insufficient understanding of the romval mechanism and lack of powerful method for performance enhancement.To solve above problems,this study designed a cross-flow MABR for synthetic wastewater treatment,investigated the biomass changes,microbial response to different influent components and membrane surface roughness with highsequencing techonology,novel in-site characterization and mathematical models.The results in this study showed that,MABR using non-woven fabric was feasible for pollutants removal.Firstly,C/N ratio had an evidently positive correlation with the biofilm thickness,which was attributed to the richness increases of the aerobic heterotrophs and nitrifying bacteria.While higher C/N ratio would deteriorate the nitrification due to the inferior position of nitrifying bacteria in the competition for oxygen.Secondly,Higher salinity can slightly increase the biofilm thickness.Nevetheless,higher salinity inhibited the activity of aerobic heterotrophs and decreased the richness of nitrifying bacteria,which led to the deterioration of the removal of organic pollutants and nitrification.Hot-pressed membrane assemblies had a rough surface with a unique structure to retain the biomass,while it could maintain the hydrophobicity of membrane surface for high oxygen transfer rate and no severe biofouling occurred after prolonged operation.Furthermore,MABR with modifed membrane was benefical to form a stable biofilm with a synergistic denitrifying microbial community.OLB8 might play an important role in enhancing denitrification.Besides,unique turbidity and performance fluctuation were observed in MABR during the startup phase,which might be due to the quorum-sensing effect of bacteria.These findings not only explained the performance changes and microbial community shift of the MABR under different C/N ratios and salinities,confirmed the feasibility of hotpressing method for strengthening MABR’s capability,but also provided systematic strategies for performance enhancement under different influent conditions and an efficient methods of membrane modification for sustainable and cost-efftive wastewater treatment.