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Abstract A new photoelectrocatalytic (PEC) and microbial fuel cell (MFC) process was developed and applied to simultaneously remove refractory organic pollutants (i.e., phenol and aniline) from wastewater while recovering energy for in-situ utilization. The current generated by the MFC process was applied to drive the PEC reaction. Compared with single PEC or MFC processes, the PEC-MFC combined process showed higher pollutant and chemical oxygen demand (COD) removal capacities and electricity production. Over 95% of the phenol or aniline was removed by these process, even at high initial concentrations. The COD removal efficiencies for phenol and aniline were ca. 96% (from 700 to 29 mg L−1) and 70% (from 165 to 49 mg L−1), respectively. Although the PEC process showed a limited contribution to phenol and aniline removals (16.5% and 43%, respectively), the utilization of PEC-treated phenol or aniline streams resulted in a MFC with higher voltage output, higher coulombic efficiency, maximal volumetric power density, and lower internal resistance as compared to untreated water. High-performance liquid chromatography coupled with mass spectrometry measurements revealed quinones/hydroquinones and low molecular weight organic acids to be produced as intermediates after the PEC process, which could improve the production of electricity in the MFC. Highlights • A new process composed of photoelectrocatalysis (PEC) and microbial fuel cell (MFC) was developed. • PEC-MFC may simultaneously remove pollutants and recover energy for in-situ utilization. • The (hydro)Quinones and low-molecular-weight organic acid as products from PEC increase electricity production of MFC. • A consecutive, dynamic adsorption and degradation process in MFC supply stable current to drive PEC. [ABSTRACT FROM AUTHOR]

As a viable wastewater treatment and energy recovery technology, microbial fuel cell (MFC) requires more research with regard to the simultaneous achievement of high-quality effluent and high power generation. In this study, a novel flow-through carbon-based composite anode configuration is proposed, which combines the carbon cloth of two-dimensional anode with wooden granular activated carbon of three-dimensional anode. The proposed configuration enhances the performance of power production and chemical oxygen demand degradation by promoting the mass transfer, reducing internal resistance and increasing bioburden. Microbial fuel cell with the composite anode exhibited the highest maximum power density (1300 ± 50 mW m−2) and the highest chemical oxygen demand removal rate constant (0.155 ± 0.007 h−1) compared with the microbial fuel cell using the carbon cloth anode (1136 ± 46 mW m−2 and 0.072 ± 0.008 h−1) or the wooden granular activated carbon anode (1045 ± 32 mW m−2 and 0.129 ± 0.009 h−1). Meanwhile, at a lower chemical oxygen demand concentration (about 48 mg L−1), the microbial fuel cell with the composite anode maintained a current density of 2.4 A m−2, which is 18% higher than the wooden granular activated carbon anode (2.04 A m−2) and 400% higher than the carbon cloth anode (0.48 A m−2). The cyclic voltammetry and electrochemical impedance spectroscopy tests confirmed that the composite anodes displayed better electrochemical performance. Improving the flow rate and reducing the external resistance could effectively enhance the power production and chemical oxygen demand removal performance of microbial fuel cells, while the computational fluid dynamics simulation intuitively demonstrated the positive effect of the composite anode on chemical oxygen demand degradation. These results suggest that the flow-through composite anode provides a feasible strategy to simultaneously enhance the power generation and improve the effluent quality. Image 1 • A composite anode was constructed by optimizing 2D and 3D carbon anode materials.. • Flow-through composite anode MFC had higher power generation and COD removal rate. • Flow-through composite anode MFC maintained high power generation at low COD. • Reducing external resistance and improving flow rate enhanced the MFC performance. • Flow-through composite anode MFC was proved better COD removal in CFD simulation. [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]