Search

A binder-free, pseudocapacitive anode was fabricated by coating reduced graphene oxide (rGO) and manganese oxide (MnO 2 ) nanoparticles on stainless steel fibre felt (SS). Microbial fuel cell (MFC) equipped with this novel anode yielded a maximum power density of 1045 mW m −2 , 20 times higher than that of a similar MFC with a bare SS anode (46 mW m −2 ). Transient-state regulation (TSR) was implemented to further improve the MFC’s power generation. The optimal TSR duty cycle ranged from 67% to 95%, and the MFC’s power density increased with TSR frequency. A maximum power density output of 1238 mW m −2 was achieved at the TSR duty cycle of 75% and the frequency of 1 Hz, 18.4% greater than that obtained from the steady state operation. The TSR mode delivered better MFC performance especially when the external resistance was small. Long-term operation tests revealed that the current density and power density yielded in the TSR mode were on average 15.0% and 32.7% greater than those in the steady state mode, respectively. The TSR mode was believed to reduce the internal resistance of the MFC while enhance substrate mass transfer and electron transfer within the anode matrix, thereby improving the MFC performance. [ABSTRACT FROM AUTHOR]

A novel anode is fabricated by electrodepositing manganese dioxide (MnO 2 ) on carbon felt to promote MFC's power production. Compared to the bare carbon felt anode, when the electrodeposition time increases to 60 min, the anode capacitance improves 46 times. The maximum power density of the MFC with the MnO 2 -coated anode reaches 3580 ± 130 mW m −2 , 24.7% higher than that with the bare carbon felt anode (2870 mW m −2 ). MnO 2 is believed to facilitate extracellular electron transfer and accordingly improve the power output. Three anode substrate circulation modes, i.e., flow-through, side-flow, and no-flow, are applied. Electrochemical impedance spectroscopy (EIS) tests reveal that flow-through mode decreases the anode mass transfer resistance by 41.4% compared to the no-flow mode and contributes to the MFC's power production improvement. [ABSTRACT FROM AUTHOR]

A novel stacked microbial fuel cell (MFC) which had a total volume of 72 L with granular activated carbon (GAC) packed bed electrodes was constructed and verified to present remarkable power generation and COD removal performance due to its advantageous design of stack and electrode configuration. During the fed-batch operation period, a power density of 50.9 ± 1.7 W/m 3 and a COD removal efficiency of 97% were achieved within 48 h. Because of the differences among MFC modules in the stack, reversal current occurred in parallel circuit connection with high external resistances (>100 Ω). This reversal current consequently reduced the electrochemical performance of some MFC modules and led to a lower power density in parallel circuit connection than that in independent circuit connection. While increasing the influent COD concentrations from 200 to 800 mg/L at hydraulic retention time of 1.25 h in continuous operation mode, the power density of stacked MFC increased from 25.6 ± 2.5 to 42.1 ± 1.2 W/m 3 and the COD removal rates increased from 1.3 to 5.2 kg COD/(m 3 d). This study demonstrated that this novel MFC stack configuration coupling with GAC packed bed electrode could be a feasible strategy to effectively scale up MFC systems. [ABSTRACT FROM AUTHOR]