Biohydrogen production through dark fermentation by a microbial consortium using whey permeate as substrate

Area of Science:

• Biotechnology
• Renewable Energy
• Microbial Fermentation

Background:

• Global hydrogen production relies on finite fossil fuels.
• Biological hydrogen (H2) production via dark fermentation is an emerging sustainable alternative.
• Research is needed to optimize biohydrogen yields and efficiency.

Purpose of the Study:

• To evaluate the impact of initial pH, ferrous sulfate (FeSO4), and ammonium sulfate ((NH4)2SO4) concentrations on biohydrogen production.
• To determine optimal conditions for maximizing hydrogen yield and productivity.
• To investigate the kinetics of biohydrogen production and identify key metabolites.

Main Methods:

• Dark fermentation process conducted in batch mode under anaerobic conditions.
• Utilized a microbial consortium with cheese whey permeate as the carbon source.
• Employed a central composite design 2((3)) to analyze variable effects and optimize parameters.

Main Results:

• Optimal biohydrogen yield of 4.13 mol H2/mol lactose and productivity of 86.31 mmol H2/L/day achieved.
• Optimum conditions: initial pH 7.0, FeSO4 at 0.6 g/L, and (NH4)2SO4 at 1.5 g/L.
• Modified Gompertz equation accurately modeled hydrogen production kinetics (R² = 0.98).

Conclusions:

• Cheese whey permeate is a viable substrate for biohydrogen production.
• Optimized fermentation parameters significantly enhance hydrogen yield and productivity.
• Lactic and butyric acids were identified as major fermentation by-products.