| Anaerobic membrane bioreactor(An MBR)has successfully combined anaerobic biological treatment process with membrane filtration technology to effectively increase the concentration of anaerobic microorganisms and achieve better operation effect,and has become a research hotspot.However,the aggravation of membrane fouling and the low efficiency of wastewater energy recovery have become technical problems that restrict its development.Therefore,in order to achieve a sustainable wastewater treatment technology to help achieve "carbon peak",this study proposed to use the surface conductive hollow fiber membrane as a dual-function cathode to form a coupling system with An MBR to take advantage of the bioelectrochemical system to enhance the anaerobic digestion process and inhibit membrane fouling.Based on the above background,firstly,the operation of different electric fields in the coupled system was studied to clarify the mechanism of the influence of the surface conductive hollow fiber membrane on the methanogenesis and membrane fouling regulation by anaerobic digestion.Secondly,the strengthening effect of the anaerobic bioelectrochemical system treatment was investigated by changing the coverage rate of the biocathode,and the formation mechanism of mixed liquid and cake layer of the coupling system was explored.Finally,the relationship between the applied voltage,system efficiency,and microbial community composition in the coupling system were explored according to the change of biocathode and anaerobic digestion performance under gradient voltage.Key findings were as follows:A surface-conducting anaerobic membrane bioreactor(S-An EMBR)was constructed to compare its wastewater treatment performance,membrane fouling control and methane generation with conventional anaerobic membrane bioreactor with or without external voltage,respectively.The results showed that the substrate removal rate in the S-An EMBR supernatant was increased by 18.61 ± 1.56% and 30.75 ± 2.31%compared with the control reactor,respectively,which significantly enhanced the functional microbial community enrichment effect.Electrochemical analysis showed that the stronger redox peak intensity of S-An EMBR biocatonic cathode was helpful to enhance the hydrogenophilic methanogenesis process,which was the key factor for increasing methane production by 54.44% and 113.92%,respectively.Furthermore,the larger floc size significantly reduced the second-stage membrane fouling rate with SAn EMBR,thereby reducing irreversible membrane fouling.According to the operation condition of S-An EMBR,different coverage coupling systems(20%,40%,60%)were proposed to evaluate the effect.The results showed that the removal rate of total organic carbon(TOC)in the supernatant of the 40%coupling system increased to 75%,and the methane production increased to 820 m L/d.It was found that 40% coverage had a more prominent enrichment effect on the main functional bacteria,which improved the selectivity of microbial genera.In addition,the high coverage operation provided the support of the cake layer during the compression process,which not only relieved the compression,but also improved the porosity of the cake layer to achieve a longer operation effect,but promoted the attachment of small molecular organic matter that caused irreversible fouling.The response mechanism of the coupled system to the gradient voltage was discussed.The results showed that the increasing voltage could improve the degradation efficiency of organic matter and the anaerobic methanogenic capacity,reduce the thickness of the fouling layer and the filtration resistance,improve the membrane fouling resistance and maintain the activity of the biofilm.However,high voltage could affect the stability of methanogenic bacteria,inhibit the proliferation of Methanosaeta and Methanobacterium,and affect the operation performance of the reactor. |
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