Abstract
<title>Abstract</title> <p>Hydrogen conversion efficiency is the primary factor limiting the large-scale production of hydrogen from straw fermentation. This study applied freeze-thaw pretreatment to improve straw bioavailability and combined it with coal gangue addition to enhance acid and hydrogen production, while evaluating environmental benefits. Comparison of hydrogen yields before and after pretreatment showed a 27.5% increase in hydrogen production from pretreated straws. After gangue addition, both hydrogen yield and the concentration of volatile fatty acids (VFAs) in the fermentation broth first increased and then decreased with decreasing gangue particle size and increasing dosage. The maximum hydrogen yield was achieved with 80‑mesh gangue at a dosage of 30 g/L, resulting in a 31.5% increase over the control group. Additionally, the incorporation of coal gangue into anaerobic digestion systems reduced carbon dioxide emissions by 32.1%, demonstrating significant environmental benefits and contributing to the synergistic achievement of waste resource utilization and carbon emission reduction goals.</p>