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Microbial desalination cells are considered a low-energy-consumption, clean technology to simultaneously purify wastewater and desalinate saline water by utilizing the in situ energy source contained in wastewater. To enhance desalination performance and achieve an optimal membrane stack configuration, an enlarged stacked microbial desalination cell (SMDC) has been developed and tested with 6–14 desalination cells. The cross-membrane area of the enlarged SMDC is 100 cm 2 . The anode and cathode volumes are both 200 mL. To reduce internal resistance, the width of desalination cells is kept as <0.5 mm. The optimal configuration with 10 desalination cells achieves the highest total desalination rate (TDR) of 423 mg/h and the highest charge transfer efficiency (CTE) of 836% when treating the 20 g/L NaCl solution. During this process, the junction potential across membranes increases from 0 to 374 mV, and occupies up to 74% of the total potential loss inside the SMDC. This shows that the SMDC used in this work achieves the highest TDR and CTE among the reported studies, and the junction potential should be effectively controlled to achieve the desired desalination performance in future practical applications. [ABSTRACT FROM AUTHOR]

A homogeneous carbon membrane with multi-functions of microfiltration, electron conduction, and oxygen reduction catalysis was fabricated without using noble metals. The produced carbon membrane has a pore size of 553 nm, a resistance of 6.0 ± 0.4 Ω cm 2 /cm, and a specific surface area of 32.2 m 2 /g. After it was assembled in microbial fuel cell (MFC) as filtration air cathode, a power density of 581.5 mW/m 2 and a current density of 1671.4 mA/m 2 were achieved, comparable with previous Pt air cathode MFCs. The filtration MFC was continuously operated for 20 days and excellent wastewater treatment performance was also achieved with removal efficiencies of TOC (93.6%), NH 4 + –N (97.2%), and total nitrogen (91.6%). In addition, the carbon membrane was much cheaper than traditional microfiltration membrane, suggesting a promising multi-functional material in wastewater treatment field. [ABSTRACT FROM AUTHOR]

A microbial fuel cell (MFC), as a cleaner wastewater treatment process, can recover electricity from organic wastes. However, high power production and high quality effluent are difficult to achieve simultaneously. In this study, a novel filtration composite anode (FCA), which combined carbon fiber brush and carbon textile was proposed to enhance COD removal and power generation performance of MFCs. The COD removal rate constant of MFCs with the filtration composite anode (FCA-MFC) was 0.33 h −1 , much higher than that of MFCs with single brush anode (FB-MFC) (0.23 h −1 ) or textile anode (FT-MFC) (0.18 h −1 ) in the recirculation mode, and also exceeded that of CA-MFC in non-recirculation mode (0.12 h −1 ). FCA-MFC delivered a maximum power density of 1140 mW m −2 at a recirculation rate of 2 mL min −1 , which was higher than the FB-MFC (990 mW m −2 ) and the FT-MFC (80 mW m −2 ) and its counterparts in non-recirculation mode (1000 mW m −2 ). Moreover, the FCA-MFC maintained a higher current density (4.0 A m −2 ) than the other two MFCs until the COD decreased to 40 mg L −1 at an external resistance of 100 Ω. CV and EIS tests verified a higher electrochemical performance of the filtration composite anode. These results demonstrated higher COD removals and power generation of the composite anode at ambient temperature, resulting from the filtration effect that facilitated mass transfer, increased microbial colonization, and improved electrochemical activity. Considering the high-quality effluent and high power generation, the filtration composite anode configuration promises a great potential for sustainable wastewater treatment application. [ABSTRACT FROM AUTHOR]

Utilization of two-electron oxygen reduction reaction (ORR) in bioelectrochemical systems (BES) is a novel way to generate H 2 O 2 from wastewater, and cathode catalyst is a key factor affecting ORR performance. Here, the catalytic performance of plain graphene, oxidized graphene and graphene oxide (GO) in microbial fuel cells (MFCs) and the influence of oxygen-containing functional groups are reported. Oxidized graphene air-cathode had 78% and 131% higher H 2 O 2 productions than plain graphene cathode respectively in an abiotic reactor and an MFC. GO showed nearly no H 2 O 2 production in the tests. XPS revealed that oxygen atomic fraction of oxidized graphene reached 5.7%, mostly in the form of C O C. These results show that oxidized graphene had good catalytic performance for H 2 O 2 production, and oxygen-containing functional groups, especially C O C could significantly enhance its performance, but overoxidation worked adversely. Meanwhile, using oxidized graphene air-cathode could realize simultaneous wastewater treatment, power output and H 2 O 2 generation in MFCs. [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]