Enhancing bioelectricity generation from wastewater in microbial fuel cells using carbon nanomaterials

BACKGROUND Microbial fuel cells (MFCs) offer a promising approach for treating wastewater and generating electrical energy simultaneously. However, their implementation in wastewater treatment plants is hindered by the limited electricity generation, often attributed to the electrolyte's high resistance. This study aimed to improve bioelectricity generation in MFCs by adding nanomaterials to the electrolyte to enhance conductivity. RESULTS Three types of nanomaterials – carbon nanotubes (CNTs), graphitic carbon nitride (g‐C3N4), and reduced graphene oxide (r‐GO) – were synthesized and addition to the electrolyte at a concentration of 50 mg in 1.5 L. MFC performance was evaluated, employed a hydraulic retention time (HRT) of 140 h, and compared to a control with no nanomaterials added. The addition of nanomaterials significantly improved MFC performance. Compared to the control, the MFCs with CNTs, g‐C3N4, and r‐GO exhibited higher voltage: 1.301 V (CNTs), 1.286 V (g‐C3N4), 1.280 V (r‐GO) versus 0.570 V (control); increased power density: 14.11 mW m−3 (CNTs), 13.78 mW m−3 (g‐C3N4), 13.66 mW m−3 (r‐GO) versus 2.71 mW m−3 (control); enhanced areal power density: 21.06 mW m−2 (CNTs), 20.57 mW m−2 (g‐C3N4), 20.39 mW m−2 (r‐GO) versus 4.04 mW m−2 (control); and improved coulombic efficiency: 19.43% (CNTs), 19.19% (g‐C3N4), 19.11% (r‐GO) versus 8.54% (control). CONCLUSION Incorporating nanomaterials into the MFC electrolyte significantly increased bioelectricity generation by 5.21 times and coulombic efficiency by 2.28 times compared to the control. This improvement is attributed to the high specific surface area of the nanomaterials, which facilitates the adhesion and growth of microorganisms around the anode, enhancing direct electron transfer. © 2024 Society of Chemical Industry (SCI).