Effect of iron concentration on hydrogen fermentation

Area of Science:

• Biotechnology
• Microbiology
• Biochemical Engineering

Background:

• Microbial hydrogen production is a sustainable energy source.
• Iron is a crucial cofactor for many microbial enzymes involved in fermentation.
• Optimizing iron concentration is key to maximizing hydrogen yield and efficiency.

Purpose of the Study:

• To investigate the impact of varying iron (FeCl2) concentrations on microbial hydrogen production.
• To determine the optimal iron concentration for maximizing hydrogen yield and production rate.
• To analyze the effect of iron on the production of other fermentation byproducts and biomass.

Main Methods:

• Utilized mixed microorganisms from a soybean-meal silo.
• Cultured microorganisms in sucrose solution with FeCl2 concentrations ranging from 0 to 4,000 mg/L.
• Maintained a constant temperature of 37°C.
• Measured hydrogen production rate, yields of hydrogen and byproducts (acetate, propionate, butyrate, ethanol, butanol), sucrose degradation efficiency, and biomass production yield.

Main Results:

• Maximum specific hydrogen production rate of 24.0 ml/g VSS/h at 4,000 mg FeCl2/L.
• Optimal iron concentrations for maximum yields: hydrogen (800 mg/L), acetate (3 mg/L), propionate (200 mg/L), butyrate (200 mg/L), ethanol (5 mg/L), and butanol (3 mg/L).
• High sucrose degradation efficiency (close to 1.0) observed between 200-800 mg FeCl2/L.
• Maximum biomass production yield of 0.283 g VSS/g sucrose at 3,000 mg FeCl2/L.

Conclusions:

• Iron concentration significantly influences microbial hydrogen production and fermentation pathways.
• Specific iron concentrations are optimal for maximizing hydrogen yield, byproduct formation, and biomass production.
• Controlled iron supplementation can enhance the efficiency of microbial hydrogen production from sucrose.