Study on the characteristics of H₂ and CH₄ production by bio-fermentation from sorghum straw pretreated with NaOH

Sorghum straw, as a renewable resource, has a huge yield. Burning or burying it not only is environmentally unfriendly but also causes resource waste. In order to develop the potential of sorghum straw and explore its ability to produce hydrogen and methane, single-factor analysis was used to optimize the effects of parameters such as solid–liquid ratio, alkali concentration, treatment time, and temperature on the alkaline pretreatment of sorghum straw. Subsequently, the hydrolysis products were evaluated for hydrogen production through photo fermentation with Rhodobacter sphaeroides HY01, as well as methane production through dark fermentation with fresh cow manure filtrate. Different factors had varying effects on the potential production of H₂ and CH₄ from the hydrolysis products of sorghum straw treated with NaOH. The research results indicated that the optimal pretreatment conditions for the maximum cumulative production of H₂ and CH₄ from sorghum straw were solid–liquid ratio of 1:10, alkali concentration of 2%, treatment time of 30 min, and temperature of 105 ℃. Under these conditions, the peak yields reached 3073 ± 126 mL-H₂/L and 1419 ± 52 mL-CH₄/L, respectively.