Research On Removal Characteristics Of Dye Wastewater Using Dual-anode MFC And BER Coupling Technology

In this study,based on microbial fuel(MFC)and biofilm electrode reactor(BER),the traditional single-anode MFC was transformed into a dual-anode MFC,which increased the effective reaction space in the anode region and improved degradation efficiency.Combining the characteristics that MFC provided electrical energy and BER required electricity,MFC and BER were used to construct coupled systems.In the coupled systems,BER acted as pre-processing device and its effluent was used as the influent of MFC,the electrical energy generated by MFC was supplied to BER,and realized the double coincidence of coupled system in energy and matter.The reactive brilliant red X-3B was selected as the target pollutant,a dual-anode MFC-BER coupled system and a dual-anode MFC stack-BER coupled system were constructed for the treatment of dye wastewater,the electrical properties and degradation performance of X-3B by dual-anode MFC system and the above coupled systems were investigated.The main results were as follows:A dual-anode MFC system was constructed to study the effects of influent X-3B concentration,HRT and anode spacing on degradation and bio-electricity production performance.The results show that with the increase of influent X-3B concentration,the decolorization rate and COD removal rate of system are also decreased,but the decolorization rate of the dual-anode MFC can be increased by 19.10%and the COD removal rate can be improved 19.23%compared with the single-anode MFC;with the decrease of HRT,the decolorization rate and COD removal rate of the dual-anode MFC increased first and then decreased.When the HRT is 1.5d,the decolorization rate and COD removal rate reach the maximum,and the values are 96.34%and74.16%.When the anode spacing is set to 10 cm,the decolorization rate of the system is 10.74%higher than that of the dual-anode MFC system with the anode spacing of5cm and the COD removal rate can be increased by 3.59%.The dual-anode MFC has two anode layers and more electrons can be recovered on the circuit.A series of intermediate products during the degradation of X-3B were analyzed by UV-Vis spectral scanning and gas chromatography mass spectrometry.The results of high-throughput sequencing show that the anode in the dual-anode MFC increased the relative abundance of producing bacteria compared with the traditional single-anode,while the upper anode microbial population in the dual-anode MFC is more abundant than the lower anode.In addition,in single-anode and dual-anode MFCs,the types of degrading bacteria are also different.A dual-anode MFC-BER coupled system was constructed to study the operating characteristics of each unit and the degradation performance of the coupled system in the treatment of dye wastewater and to explore the effect of current on each unit of the coupled system.The results show that compared with the control group,the decolorization effect of the BER unit on X-3B is significantly enhanced,and the decolorization rate can be increased by 28.68%;the battery performance of MFC unit is enhanced and the output power can reach 0.169W/m~3.By comparing the two states before and after coupling,it can be found that when the system is fed with X-3B of2500mg/L,the coupling method improves the final decolorization rate by 14.92%and the COD removal rate by 8.06%.The coupled system is a whole and the change of the degradation performance of the BER unit directly affects the change of the degradation performance of the MFC unit.Within a certain range of current intensity,the greater the current flowing through the BER unit,the greater the effect of the BER unit degrades X-3B,the more organic load is reduced for subsequent MFC units,and the overall degradation performance of the coupled system is better.A dual-anode MFC stack-BER coupled system was constructed to study the operating characteristics of BER unit and MFC unit in the coupled system,and different types of coupled system were analyzed from multiple indexes such as degradation performance,bio-electricity production performance and microbial community.The stack coupling method can significantly increase the current output of the coupled system and the degradation performance of the coupled system is better than other various systems.Record the two MFCs in the coupled system as MFC-1 and MFC-2 respectively and the performance of the MFC-2 unit in the coupled system is better than that of the MFC-1 unit.The final decolorization rate of X-3B is up to 97.13%,and the COD removal rate is up to 75.17%.The appearance of microorganisms is related to the environment in which they exist.The main microorganisms of the BER unit and the MFC unit in the coupled system are not the same.The benzene-degrading bacteria Longilinea can be regarded as a dominant functional bacteria in the BER unit,but its relative abundance is low in the MFC unit.When the system is coupled,the relative abundance of Lactococcus in the MFC-1and MFC-2 units varies from zero to some;the relative abundance of Desulfovibrio is significantly improved,this phenomenon indicates that the coupling method enhances the processing performance of the system.