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This study uncovered microbial characteristics of bioelectricity generation and dye decolorization in single-chamber microbial fuel cells (MFCs) using activated sludge for wine-containing wastewater treatment. Phylogenetic tree analysis on 16S rRNA gene fragments indicated that the predominant strains on anodic biofilm in acclimatized MFCs were Gamma-Proteobacteria Aeromonas punctata NIU-P9, Pseudomonas plecoglossicida NIU-Y3, Pseudomonas koreensis NIU-X8, Acinetobacter junii NIU-Y8, Stenotrophomonas maltophila NIU-X2. Our findings showed that the current production capabilities of these pure strains were only ca. 10% of those of their mother activated sludge, indicating that synergistic interactions among microbes might be the most influential factor to maximize power generation in MFCs. Plus, these electrochemically active strains also performed reductive decolorization of C.I. reactive blue 160, suggesting that bioelectricity generation might be directly associated to azo dye decolorization to deal with electron transfer on anodic biofilm in MFCs.

This study tended to explore factors (e.g., initial substrate concentration, microbial species) affecting electricity generation of air-cathode single-chamber microbial fuel cell (MFC) under fed-batch mode of operation. The maximum coulombic efficiency (CE) and power density taking place at initial concentration of 300 mg COD/L were 8.16% and 68.5 mW/m2, respectively. Rich media would stably provide power output in MFC for long periods of time. As part of COD removal was used for aerobic degradation rather than bioelectricity generation, lower CE values (max. 8.16%) in MFCs were revealed. According to profiles of protein expression and PCR-augmented 16S rRNA analyses for strain identification, >99.5% of nucleotide sequence of predominant pure strains in MFC was identical to type strain Aeromonas punctata.

This study explored dye decolorization and bioelectricity generation of indigenous Proteus hauseri ZMd44 for dye-bearing wastewater treatment. Chemical structures of azo dyes apparently affected the performance of dye biodecolorization. Additions of diazo dye C.I. reactive blue 160 (RBu160) stimulated simultaneous dye decolorization and bioelectricity generation of ZMd44 in single chamber microbial fuel cells (MFCs). However, high-level additions of RBu160 repressed capabilities of power production in MFC due to competition of electrons used for reductive decolorization. Decolorized intermediates of RBu160-phenyl methadiamine and 5-sulfoanthranilic acid as electron shuttles might mediate electron transport for current generation in MFC.