Performance And Microbial Mechanism Of Bioelectrochemical System During Brewery Wastewater Treatment

Bioelectrochemical systems(BESs)are a promising technology that uses electroactive microorganisms to degrade organic matter in wastewater and generate electricity simultaneously.Microbial community and metabolic activity of anode biofilm are important to recover electrical energy from wastewater in BESs.Aiming at the anode biofilm cultured with brewery wastewater,this study investigated the stratified pattern of microbial community structure and activity during different development stages of biofilm,and analyzed the relationship between BESs performance treating brewery wastewater and anode biofilm heterogeneity.As an attempt to improve the metabolic activity of anode biofilm and the performance of BESs,the effect of buffer capacity on biofilm heterogeneity was investigated using different concentration of phosphate buffer.The mechanism of buffering capacity effecting BESs performance was investigated from the perspective of microbial community distribution,metabolic activity and electrochemical activity of the anode biofilm.The main conclusions of this study are as follow:(1)Compared with the non-polarized biofilm,the polarized biofilm removed the organic matter in brewery wastewater more effectively,and playing an important role in reducing energy consumption and electricity recovery.The metabolic activity of the anode biofilm decreased gradually during the operation period,resulting in the formation of a "dead inside and living outside" biofilm structure in the later stage.Geobacter was the dominant bacteria in the anode biofilm,and its distribution in the biofilm changed over the operation time of BESs.At late stage of operation,Geobacter was intensively enriched in inner the layer of the anode biofilm whileelectrochemically inactive bacteria(EIB)mainly distributed in the outer layer of the anode biofilm.(2)Increasing the buffering capacity of the BESs not only contributed to degrade the high organic loading wastewater,and also enhanced the stability of high electrical current generation.In addition,BESs with high concentration of phosphate buffer could diminish proton accumulation within anode biofilm,which is helpful for maintaining the metabolic activity and electrocatalytic activity of biofilm,and further increasing the efficiency of extracellular electron transfer.The buffering capacity of BESs influenced the microbial diversity of the anode biofilm.More typical exoelectrogens Geobacter selectively enriched on the electrodes in the BESs with high concentration of phosphate buffer,which is benefit to develop an anode biofilm with excellent performance.