Cathodic biofouling control by microbial separators in air-breathing microbial fuel cells

Area of Science:

• Environmental Science
• Electrochemistry
• Biotechnology

Background:

• Microbial fuel cells (MFCs) with air-breathing cathodes offer eco-friendly wastewater treatment but suffer from biofouling, reducing performance.
• Biofouling of the cathode diminishes catalytic activity and operational stability in MFCs.
• Maintaining cathode performance is crucial for the long-term viability of MFC technology.

Purpose of the Study:

• To develop and evaluate a novel microbial separator for air-breathing MFCs.
• To prevent biofouling on the cathode surface and preserve its catalytic activity.
• To enhance the stability, power density, and efficiency of MFCs during prolonged operation.

Main Methods:

• A novel microbial separator was designed and integrated into air-breathing MFCs.
• Microbial growth was directed towards the separator, away from the cathode.
• Electrochemical performance (charge transfer resistance, mass diffusion resistance, power density) and chemical oxygen demand (COD) removal efficiency were measured.
• Long-term operational stability and cathode diffusion characteristics were assessed.

Main Results:

• The microbial separator effectively prevented biofouling on the cathode surface.
• Low charge transfer (4.6 ± 1.3 Ω) and mass diffusion resistance (17.3 ± 6.8 Ω) were maintained.
• Stable maximum power density of 1.06 ± 0.07 W m⁻² was achieved over long-term tests.
• Chemical oxygen demand removal efficiency increased to 92% compared to 83% in fouled MFCs.
• Reduced oxygen diffusion to the anolyte indirectly promoted electroactive bacteria growth and higher currents.

Conclusions:

• The microbial separator is a highly effective strategy for preventing cathode biofouling in air-breathing MFCs.
• This innovation significantly enhances the operational lifespan and economic feasibility of MFCs by eliminating the need for cathode maintenance.
• The developed microbial separator ensures stable power generation and cost-effective performance, paving the way for industrial MFC applications.