Pyridine degradation in the microbial fuel cells

The objective of this study was to investigate the feasibility of pyridine biodegradation in the microbial fuel cell (MFC), from which electricity was generated. Experiments were initially conducted in a graphite-packed MFC (G-MFC) using a pyridine concentration of 500 mg/L combined with different glucose concentrations. Pyridine of 500 mg/L only used as the G-MFC fuel resulted in a maximal voltage of 116 mV and a maximal power density of 1.7 W/m3. The maximal voltage reached within 12 h when pyridine was totally depleted. The glucose supplement with concentrations of 500, 250, and 100 mg/L resulted in the maximum voltages of 623, 538, and 349 mV, respectively, correspondingly the maximal volumetric power densities were 48.5, 36.2, and 15.2 W/m3. Pyridine biodegradation rates reached 95% within 24 h using the G-MFC. Interestingly, after 90 d of acclimation, the biodegradation rates of pyridine in the G-MFC using pyridine only as the fuel were higher than those using the glucose-pyridine mixtures. Further experiments were conducted using a graphite fiber brush MFC (B-MFC). Compared to the G-MFC, the B-MFC enhanced the electrical charges by 89, 186, and 586% for the mixtures with ratios of glucose-to-pyridine of 1:1, 1:2, and 1:5, respectively. GC/MS analyses of the anode solution indicated that the metabolism of pyridine in the MFC was initiated by ring reduction and NH3-N production. The results suggest that pyridine may be used as the MFC fuel in practical applications of wastewater treatment.