The efficient Congo red decolorization coupled with electricity generation via G. sulfurreducens based on microbial fuel cells

In this study, the performance of microbial fuel cells (MFCs) in azo-dye decolorization coupled with electricity generation was evaluated via the model exoelectrogens G. sulfurreducens PCA. The results showed that G. sulfurreducens PCA was capable of decolorizing Congo red (CR) while producing electricity in MFCs. The extracellular reduction of CR by G. sulfurreducens PCA requires the addition of carbon substrate (20 mM NaAc) to generate electrons and then transfer them to the exterior of the cell through respiratory chain proteins. The removal efficiency of 300 mg L-1 CR in the anodic chamber MFCs (98.5%) was found to be 2.30 times higher than that of traditional anaerobic decolorization (42.9%), whereas the maximum output voltage of MFC (0.184 +/- 0.011 V) was reduced by 65.2% when compared to that without the addition of CR (0.529 +/- 0.014 V). By reducing the initial CR concentration from 300 mg L-1 to 200 mg L-1 and 100 mg L-1, the maximum output voltage of MFCs systems was increased to 0.260 +/- 0.042 V and 0.392 +/- 0.034 V, respectively, which were 41.3% and 113.0% higher than the 300 mg L-1 CR. Thus, our study stressed that the efficient azo dye decolorization in conjunction with bioelectricity generation could be realized using the MFCs system with model exoelectrogens G. sulfurreducens PCA as the biocatalyst.