Cometabolic Degradation Of Cyanide And Electrogenesis Capacity In Microbial Fuel Cell

The treatment of cyanide-containing wastewater exists many disadvantages that incloud high-cost, bad-effect, easy to cause secondary pollution, etc. Currently, cometabolic degradation of low concentration cyanide is the main research direction. Microbial fuel cell is a new technology for wastewater treatment synchronous energy recovery, which has many advantages, such as clean and efficient, energy recovery, less sludge, etc. The cyanide cometabolic degradation and electricity production were investigated by microbial fuel cells. The electricity-generating and cyanide-degrading performance of microbial fuel cell were improved by the strains and anode’s optimization. In addition, The operating parameters were determined for the electricity-generating and cyanide-degrading in MFCs.The anodic microbial community in MFC was domesticated for the improvement of cyanide-degrading by the gradient domesticated method and dilution method. The maximum voltage of438mV, power density of5.37W/m3and cyanide removal rate of99.82%were reached.10strains capable of generating electricity and degrading cyanide were harvested. Compared with the anodic microbial community, the cyanide degradation ability of the strains were excellent, whereas the electricity generation ability of the strains were low.A composite electrode was prepared by electrochemical method for improving electricity-generating and cyanide-degrading performance. With the composite electrode, the start-up time,maximum power density and cycle times of MFC, which were196h and9.27W/m3respectively, were1/3times shorter and1times higher than those corresponding values of the MFC using carbon fiber felt anode.Composite electrode can improve the electronic transfer efficiency, cyanide degradation rate and biodiversity.Microbial diversity of anode biofilm was much higher than anode slurry. Microbial diversity of anode biofilm decreased after cyanide domestication, whereas composite anode could improve the anode biofilm community diversity. Proteobacteria dominated the main ecological niche in anode biofilm.The power density of10.86W/m3and the cyanide removal rate of99.98%after35h were researched under the condition of pH of8.2, sodium acetate concentration of1.0g/L, the cyanide concentration of80mg/L. The degradation of cyanide in the MFCs followed the apparent first-order reaction kinetics. The cyanide degradation process was fit well with Andrews kinetics model with kinetic parameters:Vm=4.21h-1, Ks=42.02mg/L, Kj=114.42mg/L, respectively. These results showed that the MFC technology is feasible for the electricity-generating and cyanide-degrading, and the discharged wastewater reached the first grade of the national standard for wastewater discharge. It provided a theoretical basis for the practical treatment of cyanide-containing wastewater.