Study On Co-generation And Microbial Diversity Of Hexavalent Chromium Reduction From Cathode Of Bicompartment Microbial Fuel Cell

The pollution and energy shortage of wastewater containing heavy metals(Lesd,Chrome,and Mercury,etc)are still important environmental problems to be solved urgently in today's social development.Microbial fuel cells(MFCs)are promising emerging bioelectrochemical technologies that meet the dual objectives of wastewater treatment and energy production in a sustainable manner.In this study,the purpose of reduction of hexavalent chromium and generate electricity simultaneously was achieved by changing the position of the electrode distance between the two electrodes,loading different nanoscale cathode catalysts and exploring the diversity of MFCs anode biofilm.The research results obtained are summarized as follows:Different electrode spacing positions were constructed in MFCs,and the Cr(VI)reduction characteristics and the influence of bioelectric release were investigated.Through electrochemical performance test,it was found that the maximum power density of MFC-2reached 535.4 m W/m²,3.13 times that of MFC-4(171.3 m W/m²).The results further illustrate the importance of electrode spacing in MFC.As for the reduction of hexadecent chromium,when the microbial fuel cell reactor reaction reached 11 h,Cr(VI)in MFC-2 was completely reductive degradation,and the COD removal rate of MFC-2(78.25%)was 1.14,1.27 and 1.96 times higher than that of MFC-1(68.82%),MFC-3(61.67%)and MFC-4(39.85%),respectively.The diversity of anodes was analyzed,the proportion of total bacterium is more than 60%,and the microbial diversity of all MFCs is similar.The change of MFC electrode position can selectively enrich the generation of electrobacteria.It is found that it can generate electricity and store energy simultaneously by properly adjusting the position in two electrode of MFC.In this study,new WS₂/WMCNTs composite nanomaterials without precious metals were successfully prepared by a simple hydrothermal synthesis method.The WS₂/WMCNTs composite,pure WS₂nanocrystals,and single WMCNTs were firstly used as cathode catalysts in dual MFCs to explore Cr(VI)reduction and bioelectricity generation.The reduction and electrochemical performance of hexavalent chromium have been studied.The power output performance of MFCs with different cathode loads is studied.The study found that the order of the maximum output power density was WS₂/WMCNTs(141.87 m W/m²)>WS₂(114.85m W/m²)>WMCNTs(69.87 m W/m²).This indicates that WS₂/WMCNTs composite nanomaterials have higher electrochemical performance and better electrocatalytic activity than WS₂nanomaterials or WMCNTs alone.The reduction performance of Cr(VI)in MFCs with different cathode decatalysts was also evaluated.It was found that the Cr(VI)removal rate of WS₂/WMCNTs composite nanomaterials in MFCs was 77.3%,69.4%for WS₂nanomaterials and 64.6%for WMCNTs nanomaterials.It is proved that WS₂/WMCNTs composite nanomaterials have better electrical performance than WS₂nanomaterials or WMCNTs alone,and can better promote the reduction of hexavalent chromium in MFCs.These results suggest that the WS₂/WMCNTs Synthetic nanomaterials have a certain application prospect in MFC cathode catalysts.A series of microorganism on the anode biofilm of microbial fuel cell was identified and analyzed by metagenomic sequencing technology.The microbial community and species diversity on the fuel cell anode were analyzed.The relationship between samples and species as well as the relationship between microorganisms were explored.Based on statistical analysis index,the diversity analysis of a single sample and Alpha diversity index including Sobs,Chao,ACE,Shannon,Simpson,Coverage,etc were explored to obtain richness and diversity of microbial communities.