Efficient hydrogen production in single-chamber microbial electrolysis cell with a fermentable substrate under...

Area of Science:

• Biotechnology
• Environmental Science
• Electrochemistry

Background:

• Food waste presents a significant challenge for energy conversion and pollution control.
• Microbial electrolysis cells (MECs) offer a promising avenue for sustainable hydrogen (H₂) production.
• Investigating hyperalkaline conditions is crucial for optimizing MEC performance.

Purpose of the Study:

• To investigate glucose fermentation from food waste and H₂ production in a single-chamber MEC under hyperalkaline conditions.
• To evaluate the impact of varying pH and applied voltages on H₂ generation and purity.
• To understand the microbial community dynamics and metabolic pathways involved.

Main Methods:

• Utilized single-chamber MECs with glucose (1 g/L) as the substrate.
• Tested different pH values (7.0, 9.5, 11.2) and applied voltages (0.8, 1.2, 1.6 V).
• Analyzed microbial communities and mcrA gene copy numbers to assess metabolic activity.

Main Results:

• Increased pH from 7.0 to 11.2 significantly improved H₂ production, with methanogenesis inhibition.
• At pH 11.2 and 1.6 V, maximum current density reached 180 A/m³, with 93.3% H₂ purity and a yield of 7.72 mol H₂/mol glucose.
• Acetate production from glucose fermentation was the primary electron sink, and *Methanobacterium alcaliphilum* dominated archaeal communities.

Conclusions:

• Hyperalkaline conditions enhance acetate production from glucose fermentation.
• High pH inhibits syntrophic acetate-oxidizing and hydrogenotrophic methanogenesis, improving H₂ yield.
• This study demonstrates a feasible method for efficient H₂ harvesting from fermentable substrates using single-chamber MECs under hyperalkaline conditions.