Life-cycle analysis of biohydrogen production via dark-photo fermentation from wheat straw.

This study presents a life-cycle analysis using energy conversion characteristics as an evaluation index to assess the feasibility of this production method. The results indicate that for a system processing 1000 kg/h of wheat straw, the addition of 12000 kg/h of 2 wt% H2SO4 and 120 kg/h of CH3COONa yields 340,000 L/h of H2 and 348.6 kW of electricity. The energy conversion efficiency from the feedstock to the product is 21.4 %, while the efficiency from the hydrolysate to the product is 62.2 %. The total CO2 emission is 27.1 kg/h. Variations in the hydrolysate have the most significant impact on energy conversion efficiency. This study explores the feasibility of industrial-scale biohydrogen production via dark-photo fermentation from wheat straw and analyzes the energy characteristic indices and the sensitivity of these indices to key parameters.

Pilot composite tubular bioreactor for outdoor photo-fermentation hydrogen production: From batch to continuous operation.

A novel 70 L composite tubular photo-bioreactor was constructed, and its photo-fermentation hydrogen production characteristics of batch and continuous modes were investigated with glucose as the substrate in an outdoor environment. In the batch fermentation stage, the hydrogen production rate peaked at 37.6 mL H2/(L·h) accompanied by a high hydrogen yield of 7 mol H2/mol glucose. The daytime light conversion efficiency is 4 %, with 37 % of light energy from the sun. An optimal hydraulic retention time of 5 d was identified during continuous photo-fermentation. Under this condition, the stability of the cell concentration is maintained and more electrons can be driven to the hydrogen generation pathway while attaining a hydrogen production rate of 20.7 ± 0.9 mL H2/(L·h). The changes of biomass, volatile fatty acids concentration and ion concentration during fermentation were analyzed. Continuous hydrogen production by composite tubular photo-bioreactor offers new ideas for the large-scale deployment of photobiological hydrogen production.

Light energy utilization and microbial catalysis for enhanced biohydrogen: Ternary coupling system of triethanolamine-mediated Fe@C-Rhodobacter sphaeroides.

This study investigated the mediating effect of Triethanolamine on Fe@C-Rhodobacter sphaeroides hybrid photosynthetic system to achieve efficient biohydrogen production. The biocompatible Fe@C generates excited electrons upon exposure to light, releasing ferrum for nitrogenase synthesis, and regulating the pH of the fermentation environment. Triethanolamine was introduced to optimize the electron transfer chain, thereby improving system stability, prolonging electron lifespan, and facilitating ferrum corrosion. This, in turn, stimulated the lactic acid synthetic metabolic pathway of Rhodobacter sphaeroides, resulting in increased reducing power in the biohybrid system. The ternary coupling system was analyzed through the regulation of concentration, initial pH, and light intensity. The system achieved the highest total H2 production of 5410.9 mL/L, 1.29 times higher than the control (2360.5 mL/L). This research provides a valuable strategy for constructing ferrum-carbon-based composite-cellular biohybrid systems for photo-fermentation H2 production.