Enhancing hydrogen production through anode fed-batch mode and controlled cell voltage in a microbial electrolysis...

Area of Science:

• Bioelectrochemistry
• Renewable Energy Technologies
• Microbial Fuel Cells

Background:

• Microbial electrolysis cells (MECs) offer a sustainable route for converting organic waste into hydrogen fuel.
• Optimizing operational parameters is crucial for maximizing hydrogen production efficiency in MECs.
• Understanding the role of microbial communities in biocathodes is key to improving hydrogen evolution.

Purpose of the Study:

• To investigate the impact of different anode feed modes (continuous, fed-batch, batch) on hydrogen production in a fully microbial MEC.
• To evaluate the effect of applied cell voltage on hydrogen production and identify operational regions in the fed-batch mode.
• To analyze the microbial community composition of the biocathode and its correlation with hydrogen evolution.

Main Methods:

• Comparative analysis of hydrogen production rates under continuous, fed-batch, and batch anode feeding strategies.
• Chronoamperometry measurements to assess MEC performance across a range of applied voltages (0.3–1.6 V).
• Microbial community analysis using 16S rRNA sequencing to identify dominant bacteria in the biocathode.

Main Results:

• Continuous feeding yielded the highest hydrogen production (14.6 L m⁻² day⁻¹), outperforming fed-batch (12.7 L m⁻² day⁻¹) and batch modes (0 L m⁻² day⁻¹).
• The optimal applied voltage for maximum hydrogen production (12.1 L m⁻² day⁻¹) was 1.0 V, corresponding to efficient anode and cathode reactions.
• Alpha- and Deltaproteobacteria, particularly Desulfovibrio sp., were dominant in the biocathode, suggesting their significant role in hydrogen evolution.

Conclusions:

• Continuous anode feeding is superior for maximizing hydrogen production in MECs compared to fed-batch and batch modes.
• Applied voltage significantly influences MEC performance, with an optimal range identified for efficient hydrogen generation.
• The microbial community, dominated by specific proteobacteria genera like Desulfovibrio, plays a critical role in the biocathodic hydrogen evolution process.