| The problem of groundwater arsenic pollution is a global environmental problem,and traditional treatment methods have certain drawbacks.A microbial fuel cell is an experimental device that uses microorganisms as a catalyst to convert chemical energy in a fuel into electrical energy while degrading organic matter.Because of its wide fuel source,mild reaction conditions,clean and environmental protection,it has attracted the attention of many scholars since its discovery.The As???pollution caused by industrial wastewater is highly toxic,and the traditional treatment methods have many by-products and high energy consumption.This paper focuses on the electron transfer mechanism and pollutant removal effect of MFC,studies the electricity production performance and pollutant degradation effect of MFC under different conditions,and analyzes the main functional strains of anode microorganisms in MFC by analyzing the anode microbial community.The main findings are as follows:Experimental study and analysis of MFC operating conditions:sodium acetate concentration and pH.The formation of the biofilm on the anode surface is related to the carbon source substrate,and the concentration of the carbon source sodium acetate affects the competitive advantage of the electrogenic microbial population.The output voltage cycle length is proportional to the sodium acetate concentration;the maximum output voltage,current density,power density,COD removal rate,and coulombic efficiency are normally distributed as the sodium acetate concentration increases.When the concentration of sodium acetate is 640.0mg·L-1,the maximum output voltage of MFC is 703.43mV,the maximum current density is 15224.4.0mA·m-3,the maximum power density is 7294.7mW·m-3,and the COD removal rate is 85.7%.The efficiency is 18.0%.The length of the output voltage cycle is proportional to the pH;the current density and COD removal rate are normally distributed with the increase of pH;the power density and coulombic efficiency are proportional to the pH.pH affects the long-term environment of microbial production and also affects the ionization conditions of ions.At pH=7.0,the maximum output voltage of MFC is 580.0 mV,the maximum current density is 29500.0mA·m-3,the maximum power density is4000.0mW·m-3,the COD removal rate is 87.7%,and the Coulomb efficiency is10.8%.The formation of the biofilm on the anode surface is related to the carbon source substrate,and the concentration of the carbon source sodium acetate affects the competitive advantage of the electrogenic microbial population.When the concentration of sodium acetate is 640.0mg·L-1,the maximum output voltage of MFC is 703.43mV,the maximum current density is 15224.4mA·m-3,the maximum power density is 7294.7mW·m-3,the COD removal rate is 85.7%,the coulombic efficiency is18.0%.pH affects the long-term environment of microbial production and also affects the ionization conditions of ions.pH=7.0,MFC maximum output voltage 580.0mV,maximum current density 29500.0mA·m-3,maximum power density 4000.0mW·m-3,COD removal rate 87.7%,Coulombic efficiency is 10.8%.In summary,pH=7.0,sodium acetate concentration of 640.0mg·L-11 is the best operating condition for MFC.The effects of As???concentration on the arsenic production and microbial community diversity and abundance of MFC were investigated.In a complete cycle,we perform power generation performance analysis by output voltage,polarization curve,power density curve,COD,and Coulomb efficiency;and calculate As???by detecting changes in As???and As?V?concentrations in the anode chamber.The removal rate and oxidation rate reflect the degradation effect of the pollutants;the microbial community analysis observes the diversity and richness of the microbial community,and the changes of the main dominant species.Electrochemical performance analysis shows that the two polar chambers have good redox catalytic activity,and the catalytic reaction of the anode is closely related to the metabolism of microorganisms.The metabolic activity of microorganisms determines the anode reaction.The analysis of the degradation effect of the pollutants shows that the anode realizes the oxidation and detoxification of As???,and the stimulation of the microcurrent promotes the removal of heavy metals by the anode microorganisms.The output voltage is negatively correlated with As???concentration.The output voltage cycle length,open circuit voltage,current density,Coulomb efficiency,and As???removal rate show a normal distribution with the increase of As???concentration.The As???concentration was 20.0 and 30.0 mg·L-1.At this time,the system performed open circuit and closed circuit comparison,and the As?V?oxidation rate was proportional to the As???concentration.As???can increase productivity in MFC while being removed in MFC.When As???concentration is 20.0mg·L-1,the maximum output voltage obtained by MFC is 639.7mV,the maximum current density is 42000.0mA·m-2,the maximum power density is 7300.8W·m-3,and the COD removal rate is 85.8%.The efficiency is 10.7%.The arsenic removal efficiency reached 79.4%,and the As???oxidation rate reached 72.4%.Sodium acetate concentration and pH are proportional to the microbial community abundance.When MFC is added to As???,the specific functional flora changes and the richness changes.At 20.0mg·L-1 concentration,the anode flora has the highest species richness.The change of the specific functional flora in a certain operating cycle leads to the change of richness,and the richness shows a trend of steady growth and then decline with the extension of the running time.The results of microbial community analysis indicated that the dominant species of anodes were Bacteroidetes,Firmicutes and Proteobacteria.Combined with the existing research,it is speculated that Proteabacteria has a certain degradation and transformation effect on As???.In summary,It is feasible to remove As???from wastewater by MFC,and As???undergoes oxidative detoxification reaction while MFC achieves stable electricity production. |
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