Effects of substrate components on hydrogen fermentation of multiple substrates

Area of Science:

• Biotechnology
• Environmental Science
• Microbiology

Background:

• Carbohydrates are preferred substrates for hydrogen fermentation due to higher yields compared to proteins.
• Protein fermentation can involve hydrogen production followed by consumption, impacting overall recovery.
• Understanding substrate roles is crucial for optimizing biohydrogen production.

Purpose of the Study:

• To investigate the distinct roles of carbohydrates and proteins in hydrogen fermentation.
• To determine optimal substrate ratios for enhanced hydrogen yield.
• To analyze the impact of substrate composition on fermentation byproducts and pH.

Main Methods:

• Utilized multiple substrates with varying ratios of glucose (carbohydrate) and peptone (protein).
• Monitored hydrogen production and yield (mmole-H2/g-COD).
• Analyzed changes in pH and the production of ammonia during fermentation.

Main Results:

• A substrate mix of 60% glucose and 40% peptone yielded a maximum of 6.4 mmole-H2/g-COD.
• Glucose fermentation was the primary contributor to hydrogen production, not peptone.
• Higher peptone content (80% and 20%) led to significant pH drops (1.0 and 1.9 units) due to acid production, which was partially neutralized by ammonia from peptone degradation.

Conclusions:

• Optimized ratios of glucose and peptone enhance hydrogen-producing bacterial growth and hydrogen yield.
• Carbohydrates are more efficient substrates for hydrogen generation than proteins in this context.
• Ammonia generated from peptone degradation plays a role in neutralizing fermentation acids, influencing the process stability.