Study On Treatment Of Wastewater Containing Copper And Chromium By Miceobial Fuel Cell

At present,due to the acceleration of industrialization in our country,the degree of heavy metal pollution is increasing year by year.If it is discharged into water or soil,it will cause certain pollution to the environment and human body,so the removal of heavy metals is extremely important.Microbial fuel cell（MFC）,as a new type of heavy metal removal device,can use microorganisms to convert chemical energy into electrical energy and realize the removal and recovery of heavy metals.This paper takes Cu²⁺ and Cr⁶⁺ as the research object,constructs a two-chamber MFC,and analyzes the output voltage,power density,polarization curve,and Coulomb efficiency of the MFC by studying different conditions such as different oxygen content,initial concentration,cathode material,and biocathode.,Cathode efficiency and other electricity-generating characteristics,as well as the removal effect of Cu²⁺and Cr⁶⁺,and then get the operating rules under different conditions,and analyze the microbial community structure of the biocathode.The main conclusions are as follows:（1）When the dual-chamber MFC treats wastewater containing Cu²⁺,the electricity generation characteristics of MFC in the micro-oxygen（The content of DO is 6-7umol/L）state and the removal effect of heavy metal ions are better than those in the anaerobic（The content of DO is 0umol/L）state;for different initial concentration of Cu²⁺,when Cu²⁺concentration increases from 10mg/L to 200mg/L,the electrical characteristics of MFC and the removal effect of Cu²⁺ are better.When using graphite plates,titanium sheets,and stainless steel electrode sheets as cathode electrode materials,the electricity generation characteristics of MFC and the removal effect of heavy metal ions show that the results of MFC’s electricity generation characteristics and heavy metal ion removal effect are as graphite plate>titanium Sheet>Stainless steel electrode sheet.（2）When the dual-chamber MFC treats Cu²⁺ and Cr⁶⁺ mixed wastewater,the power generation characteristics of MFC in the micro-oxygen（The content of DO is 6-7umol/L）state and the removal effect of heavy metal ions are better than those in the anaerobic（The content of DO is 0umol/L）state;when the Cu²⁺ concentration is 100mg/L,the Cr⁶⁺ concentration decreases from 150mg/L to 10mg/L,the electricity generation characteristics of MFC and the removal effect of Cu²⁺ and Cr⁶⁺ are better.When graphite plates,titanium plates,and stainless steel electrode plates are used as cathode electrode materials,the electricity generation characteristics of MFC and the results of heavy metal ion removal effect are all shown as graphite plate>titanium sheet>stainless steel electrode sheet.（3）Because of the electronic competition phenomenon when Cu²⁺ and Cr⁶⁺ are mixed,it has a certain degree of inhibition on the removal of heavy metal ions.Therefore,the electricity generation characteristics and heavy metal removal effect of MFC in the treatment of Cu²⁺ and Cr⁶⁺ mixed wastewater are lower than that of MFC in the treatment of Cu²⁺-containing wastewater.（4）When applying-0.1V、-0.3V、-0.5V、-0.7V to the biological cathode MFC to treat Cu²⁺-containing wastewater,the Cu²⁺ removal effect is significantly better than that of the control group without a set potential.When the set potential is 0.5V,MFC has the best electricity generation characteristics and Cu²⁺ removal effect,which is the optimal setting potential;and compared with non-biological cathode type MFC,the electricity generation effect of biocathode type MFC is significantly better than that of non-biological cathode type.（5）The richness and uniformity of the microbial community on the biocathode showed no set potential>-0.1V>-0.3V>-0.5V>-0.7V;but the microbial community had certain differences under different set potentials.At the phylum level,the four bacterial groups Actinobacteria、Proteobacteria、 Bacteroidetes and Firmicutes on the biocathode are the dominant flora;at the genus level,Mycobacterium、Gordonia、Methylocystis and Rhodococcus are the dominant flora on the biocathode;The proportion of other flora at phylum and genus levels was relatively small.Since the electricity generation characteristics and Cu²⁺ removal effect are the best when the potential is set to-0.5V,Actinobacteria at the phylum level,and Mycobacterium at the genus level are bio-cathode type MFCs.When removing the most favorable flora in wastewater containing Cu²⁺,it promotes the reduction of Cu²⁺.