Azo dye treatment with simultaneous electricity production in an anaerobic–aerobic sequential reactor and microbial fuel cell coupled system

A microbial fuel cell and anaerobic–aerobic sequential reactor coupled system was used for azo dye degradation with simultaneous electricity production. Electricity was produced during the co-metabolism process of glucose and azo dye. A microorganism cultured graphite-granular cathode effectively decreased the charge transfer resistance of the cathode and yielded higher power density. Operation parameters including glucose concentration and hydraulic retention time were optimized. The results indicated that recovering electricity during a sequential aerobic–anaerobic azo dye treatment process enhanced chemical oxygen demand removal and did not decrease azo dye removal. Moreover, UV–vis spectra and GC–MS illustrated that the azo bond was cleaved biologically in the anaerobic chamber and abiotically in the aerobic chamber. The toxic intermediates, aromatic amines, were removed by aerobic treatment. Our work demonstrated that the microbial fuel cell and sequential anode–cathode reactor coupled system could be applied to achieve electricity production with simultaneous azo dye degradation.