Improved decolorization of dye wastewater in an electrochemical system powered by microbial fuel cells and intensified by micro-electrolysis

Electrochemical decolorization is of particular importance for the efficient treatment of dye wastewater. A promising electrochemical system powered by microbial fuel cells (MFCs) and intensified by Fe-C micro-electrolysis is proposed and enhanced decolorization of methyl orange (MO) is realized in this study. The decolorization efficiency reached as high as 97.1 ± 1.8% after 180 min of operation with initial MO concentration of 50 mg/L and applied voltage of 700 mV. Decolorization efficiency initially increased and then decreased with rising Fe-to-C ratio. In addition, efficiency was enhanced with the increase of aeration rate up to 6.0 L/min. Lower initial MO concentration and pH were also shown to facilitate MO decolorization. A study of mechanisms, with results from control tests and scavenger experiments indicated that MO decolorization was contributed by the indirect oxidation by various oxidizing substances, especially O2−, that were generated during the process. MO molecule was decomposed and low molecular weight compounds such as indolizine, hydrazide and thione were generated. This study advances the performance of MFC in dye wastewater treatment by combining with a standard technique.