The anode potential regulates bacterial activity in microbial fuel cells

Area of Science:

• Microbial electrochemistry
• Bioelectrochemical systems
• Renewable energy technologies

Background:

• Microbial fuel cells (MFCs) convert organic matter into electricity using microorganisms.
• The anode potential is a critical parameter influencing microbial activity and energy output in MFCs.
• Understanding the effect of anode potential on microbial communities is key to improving MFC efficiency.

Purpose of the Study:

• To investigate the impact of different poised anode potentials on bacterial activity and electrical performance in MFCs.
• To determine the optimal anode potential for maximizing current and power generation.
• To analyze the relationship between anode potential, microbial growth, and metabolic activity.

Main Methods:

• Operation of three MFC reactors with acetate as the substrate at poised anode potentials of 0, -200, and -400 mV vs. Ag/AgCl.
• Monitoring of charge production, power density, and current generation during a 31-day experimental period.
• Assessment of bacterial activity through maximum respiration rate and specific biomass activity measurements.

Main Results:

• The -200 mV anode potential (R(-200)) yielded 15% more charge and the highest maximal power density (199 W m(-3)).
• Bacterial respiration rates were significantly lower at -400 mV, despite higher specific biomass activity initially.
• All reactors reached similar power densities by the end, with biomass concentration increasing across reactors.

Conclusions:

• An optimal anode potential of -200 mV vs. Ag/AgCl was identified for MFCs, balancing microbial activity and growth.
• This potential enhances current and power generation by regulating bacterial behavior.
• The findings provide critical insights for designing and operating high-performance MFCs.