Hydrogen production from acidic, alkaline, and steam-exploded Bambusa stenostachya hydrolysates in dark fermentation process

Abstract

Bambusa stenostachya Hack. was subjected to two pretreatment methods including hydrothermal pretreatment and steam explosion methods for evaluating their feasibility hydrolysis to obtain sugars. Batch cultivation by a mixture of microorganisms isolated from sludge in 48 h was carried out to investigate the influence of these pretreatment methods on hydrogen production under sterile conditions. The sugar production yields by sulfuric acid (ST), phosphoric acid (PT), sodium hydroxide (HT), and ammonia (AT) solutions in an autoclave at 121 °C were 42%, 25%, 10%, and 5%, respectively. Steam explosion of raw bamboo (SE) and bamboo treated with 0.8% sulfuric acid (SES) at 230 °C for 3 min had 23% and 72% of the total sugar derived from bamboo carbohydrates, respectively. The maximum cumulative hydrogen yields were 798 (mL H2/L culture) of ST, 545.9 (mL H2/L culture) of PT, 76.7 (mL H2/L culture) of HT, 43.7 (mL H2/L culture) of AT, 204.4 (mL H2/L culture) of SE, and 1055.8 (mL H2/L culture) of SES. Ammonia solution could remove 73.6% lignin in biomass compared to 6.5% of ST, 8.3% of PT, 51.9% of HT, 14.7% of SE, and 32.4% of SES. The integration of acid and steam explosion process had enhanced hydrogen fermentation efficiency directly from bamboo biomass hydrolysate, which could be considered a desirably potential procedure for large-scale applications.