Fermentative hydrogen production from tofu-processing waste and anaerobic digester sludge using microbial consortium

Area of Science:

• Biotechnology and Bioengineering
• Renewable Energy Production
• Waste Valorization

Background:

• Tofu processing generates significant waste streams.
• Anaerobic digester sludge is a readily available nutrient source.
• Sustainable hydrogen (H2) production from organic waste is a key research area.

Purpose of the Study:

• To evaluate the fermentative hydrogen production capacity of combined tofu waste and anaerobic digester sludge.
• To optimize conditions for hydrogen production in batch and continuous modes.
• To assess the feasibility of this waste combination for scalable hydrogen generation.

Main Methods:

• Thermophilic mixed culture fermentation was employed.
• Tofu waste underwent heat-treatment with HCl to enhance soluble carbohydrate content.
• Batch and continuous fermentation experiments were conducted, varying mixing ratios, hydraulic retention time (HRT), and pH.

Main Results:

• Heat-treatment increased soluble carbohydrates in tofu waste from 2.2 to 10.4 g/l.
• Optimal mixing ratio of digester sludge was 20% (v/v) in batch mode.
• Maximal H2 production rate (12.0 l H2/l/day) and yield (2.3 mol H2/mol glucose equivalent) were achieved at HRT of 4h and pH 5.5 in continuous mode, with 50-60% H2 in headspace gas and no methane (CH4) production.

Conclusions:

• The combination of tofu-processing waste and anaerobic digester sludge is a viable and promising substrate for fermentative hydrogen production.
• Optimized conditions (HRT 4h, pH 5.5) enable efficient and selective hydrogen generation.
• This approach offers a sustainable method for converting organic waste into valuable hydrogen energy.