| In recent years,with the rapid development of mariculture industry,the problem of marine environmental pollution is becoming more and more serious due to the large amount of wastewater discharged from mariculture.Membrane bioreactor（MBR）,as a new type of high-efficiency water treatment technology,has gained wide attention in wastewater treatment.However,the membrane fouling is the main factor restricting the further development and application of MBR process in operation.Electric field attached MBR（E-MBR）shows potential advantages in improving wastewater treatment efficiency and mitigating membrane fouling.Therefore,in this study,micro-electric field was introduced into MBR system to systematically investigate the effects of micro-electric field E-MBR system and traditional MBR system on the treatment efficiency and membrane fouling control of mariculture wastewater,and high-throughput sequencing technology was used to analyze the dynamic changes of microbial community structure.The degradation rates of ammonia nitrogen（NH4+-N）,nitrite nitrogen（NO2--N）,nitrite nitrogen（NO3--N）,total nitrogen（TN）and chemical oxygen demand（COD）,as well as the activities of key denitrification enzymes and the content of adenosine triphosphate（ATP）in each system were detected to explore the efficiency of micro-electric field E-MBR system and traditional MBR system for the treatment of maraquaculture wastewater.The results showed that compared with the traditional MBR system,the micro-electric field E-MBR system could significantly improve the degradation rates of NH4+-N,NO2--N,NO3--N,TN and COD.On the one hand,the high salinity in mariculture wastewater enhanced its electrical conductivity,which enhanced the electrocatalytic effect of micro-electric field and accelerated the denitrification process.Moreover,there is a coupling synergistic effect between electrocatalytic degradation and biodegradation in the micro-electric field E-MBR system.On the other hand,compared with the traditional MBR system,the micro-electric field E-MBR system could significantly improve the activities of key denitrification enzymes and the content of ATP,thus improving the treatment efficiency of mariculture wastewater.High-throughput sequencing analysis showed that compared with the traditional MBR system,micro-electric field E-MBR system with appropriate intensity could enrich the dominant bacteria with denitrification function,thus improved the efficiency of mariculture wastewater treatment.By detecting the activated sludge characteristics,H2O2content changes,soluble microbial products（SMP）and extracellular polymeric substances（EPS）content in micro-electric field E-MBR system and traditional MBR system,the mechanism of membrane fouling mitigation in micro-electric field E-MBR system was analyzed.The results showed that compared with the traditional MBR,E-MBR system could enhance the electrostatic repulsion between the membrane foulant and the cathode membrane,and could produce H2O2in situ to remove membrane foulant.Meanwhile,compared with the traditional MBR,the contents of SMP and EPS in the micro-electric field E-MBR system were significantly reduced.Three-dimensional fluorescence spectroscopy（3D-EEM）and infrared spectroscopy（FTIR）were used to analyze the changes of fluorescence components and functional groups of EPS.The results showed that the fluorescence intensity of tryptophan protein and humic acid substances in EPS was significantly reduced,and the functional groups related to protein and polysaccharide was decreased compared with traditional MBR.In addition,high-throughput sequencing analysis showed that compared with traditional MBR,micro-electric field E-MBR system could effectively enrich dominant bacteria related to EPS degradation,significantly reduced the relative abundance of dominant bacteria involved in biofilm formation,thus improving the treatment efficiency of mariculture wastewater and effectively mitigating membrane fouling. |
