Cathodic and anodic biofilms in Single Chamber Microbial Fuel Cells.

Area of Science:

• * Bioelectrochemistry
• * Environmental Engineering
• * Renewable Energy

Background:

• * Microbial fuel cells (MFCs) offer a sustainable method for wastewater treatment and energy generation.
• * Biofilms on cathode surfaces play a crucial role in enhancing MFC performance.
• * Platinum-free cathodes are explored as a cost-effective alternative to traditional platinum-loaded electrodes.

Purpose of the Study:

• * To investigate the performance of microaerophilic biofilms on graphite cathodes in Single Chamber Microbial Fuel Cells (SCMFCs).
• * To compare the efficiency of platinum-free cathodes with platinum-loaded cathodes in SCMFCs.
• * To analyze the factors affecting power density and current generation in membraneless SCMFCs.

Main Methods:

• * Operation of membraneless SCMFCs in batch mode using wastewater and sodium acetate as substrate.
• * Periodic addition of sodium acetate and long-term experimental monitoring (over six months).
• * Performance evaluation through power density measurements, current density analysis, and quasi-stationary polarization curves.

Main Results:

• * Biofilm development on graphite cathodes led to increased power densities, reaching up to 0.5 W m⁻².
• * Optimal acetate concentration for stable power output was found to be between 0.01–0.05 M.
• * Power output decreased significantly when the media pH exceeded 9.5, irrespective of cathode type.
• * Anodic overpotential was identified as a potential limiting factor for long-term current density in SCMFCs.

Conclusions:

• * Microaerophilic biofilms on graphite biocathodes significantly enhance SCMFC performance.
• * Platinum-free cathodes demonstrate comparable performance to platinum-loaded cathodes.
• * Maintaining optimal pH and substrate concentration is crucial for maximizing energy recovery and ensuring stable operation of SCMFCs.