Long-term cathode performance and the microbial communities that develop in microbial fuel cells fed different...

Area of Science:

• Microbiology
• Electrochemistry
• Environmental Science

Background:

• Microbial fuel cells (MFCs) are devices that convert organic matter into electricity using microorganisms.
• Understanding long-term performance factors is crucial for optimizing MFC technology.
• Lignocellulose fermentation endproducts are potential substrates for MFCs.

Purpose of the Study:

• To investigate the long-term effects of different lignocellulose fermentation endproducts on MFC performance.
• To assess the impact of cathode degradation on MFC power output over time.
• To characterize microbial community evolution in MFCs under various substrate conditions.

Main Methods:

• Operated MFCs for over one year using individual substrates: acetic acid, formic acid, lactic acid, succinic acid, and ethanol.
• Monitored power densities and cathode performance degradation.
• Analyzed anode microbial communities using 16S rRNA gene sequencing.

Main Results:

• Substrate type was the primary driver of performance variations, with power densities ranging from 62 ± 1 to 835 ± 21 mW/m³.
• Cathode performance degraded over time, leading to power increases of up to 26% after biofilm removal and 118% with new cathodes.
• Anode communities were dominated by Deltaproteobacteria, including exoelectrogenic families like Rhodobacteraceae and Geobacteraceae. Pelobacter propionicus was predominant in acetic acid-fed reactors.

Conclusions:

• Substrate selection critically influences MFC performance and microbial community structure.
• Cathode biofilm accumulation and degradation significantly impact long-term MFC power generation.
• Long-term operation studies are essential for understanding and improving MFC stability and efficiency.