Research On Performance Optimization Of Microbial Fuel Cells And Treatment Of Heavy Metal Wastewater Containing Ni(Ⅱ)

Microbial fuel cells（MFCs）are modern biotechnology that uses electricity-producing microorganisms as catalysts to convert chemical energy in organic matter into electrical energy.It has broad application prospects in the treatment of organic wastewater and heavy metal wastewater.In order to improve the power generation performance of MFCs such as power density and then consolidate the application foundation of MFCs,the following researches were carried out in this study:the effect of anaerobic activated sludge inoculum on the enrichment of anode biofilms was studied,and the effect of nano-Fe₃O₄modified anode of MFCs on the power generation performance was analyzed.Finally,the removal efficiency and mechanism of MFCs in the treatment of simulated Ni（II）heavy metal wastewater were discussed,which provided some theoretical guidance for the simultaneous treatment of organic matter and Ni（II）composite polluted wastewater by single-chamber MFCs.The main conclusions are as follows:（1）Using anaerobic activated sludge as the source of electricity-generating microorganisms,the effect of different inoculum amounts on the electricity-generating performance of MFCs was studied.At an inoculum volume of 9 g/L,the electrical performance was the best,the maximum output voltage was 509 m V,the maximum power density was 600.71±17.57 m W/m²,and the COD removal efficiency was95.17±1.4%,which were significantly higher than the output powers at other inoculum volume.（2）Magnetite（Fe₃O₄）is widely distributed worldwide,which provides an inexpensive,environmentally friendly and sustainable source of additives for improving the electrochemical performance of MFCs.Fe₃O₄ nanoparticles synthesized by co-precipitation method were added to the anode chamber at different concentrations to study their effect on the electricity production performance of MFCs.The maximum power density of the MFCs with 4.5 g/L Fe₃O₄ modified carbon brush anode is approximately 1.5 times higher than that of the unmodified MFCs.Fe₃O₄nanoparticles enhanced the anode’s biocatalytic activity and electron transfer efficiency.In addition,the anodic modification of Fe₃O₄promoted the enrichment of Geobacter,and the abundance of Geobacter was positively correlated with the electricity-generating performance of MFCs.（3）The removal efficiency and mechanism of MFCs in the treatment of simulated Ni²⁺heavy metal wastewater were investigated,which provided a reference for the simultaneous removal of organic matter and heavy metal ion composite pollution in wastewater.Toxic stress of Ni²⁺reduced the microbial activities of electroactive biofilms.The addition of Ni²⁺inhibited the electricity production performance of MFCs.The electron transport performance,metal ion and COD removal efficiency of the anode biofilm decreased with the increase of Ni²⁺concentration.The community structure composition of electroactive biofilms changed with Ni²⁺concentration increased.The abundance of electrogenic bacteria Geobacter decreased from 36.04%to 12.05%,while Desulfovibrio increased from 8.45%to 17.75%.