Cascade hydrogen production from butyrate-type straw fermentation effluent using a microbial electrolysis cell

Area of Science:

• Biotechnology
• Renewable Energy
• Environmental Science

Background:

• Butyric acid in fermentation effluent poses degradation challenges.
• Corn straw is a potential substrate for biohydrogen production.
• Microbial electrolysis cells (MECs) can treat effluent and produce hydrogen.

Purpose of the Study:

• To optimize hydrogen production from corn straw fermentation effluent using MECs.
• To investigate the effect of anode enrichment strategies on hydrogen yield and effluent treatment.
• To analyze the microbial community structure and identify key species for efficient degradation.

Main Methods:

• Dark fermentation of corn straw for hydrogen production.
• Enrichment of MEC bioanodes with different substrates (butyric acid, acetic acid, effluent).
• Investigation of anode enrichment, substrate concentration, and applied voltage effects.
• High-throughput sequencing for microbial community analysis.

Main Results:

• Maximum hydrogen yield of 943 mL g^-1 and production rate of 3.62 m³ m^-3 d^-1 achieved with butyric acid-enriched anode at 0.6 V.
• Butyric acid degradation rate increased by 35.1% and COD removal by 25% compared to effluent enrichment.
• Anode enrichment with butyric acid led to higher microbial diversity and abundance of *Syntrophomonas* (8.7%).

Conclusions:

• Butyric acid oxidation is the rate-limiting step in hydrogen production from straw fermentation effluent.
• A two-stage cascade process enhances straw conversion and hydrogen production efficiency.
• This method offers simultaneous purification of fermentation effluent, valuable for large-scale biohydrogen production.