Effect of intermittent ball milling on high-solids enzymatic saccharification of rice straw

The economy of the bioethanol production process can be improved by increasing the initial solid content and reducing the reaction time. The enzymatic approach utilizing intermittent ball milling has been proposed as a viable solution to tackle these challenges effectively. This study demonstrated that intermittent ball milling during high-solids enzymatic hydrolysis for a duration of 12 h showed a significantly higher total sugar yield, with an increase of 25.8% compared to continuous ball milling enzymatic hydrolysis method. The subsequent investigation comprehensively examined the impact of multi-conditional parameter variations on sugar yield during intermittent ball milling. The orthogonal experiment resulted in the determination of optimal process parameters, including a solid–liquid ratio of 25%, ball milling time (per cycle) of 5 min, ball milling frequency of 50 Hz, 6 balls used during the process, and an incubation temperature of 50℃ under optimized conditions. The conditions led to the achievement of a total reducing sugar concentration of 103.8 g/L, a total sugar yield of 415.1 mg/g, and an enzymatic hydrolysis yield of 72.4%. The optimized intermittent ball milling process exhibited superior hydrolysis yield and shorter reaction time compared to other enzymatic methods with untreated biomass. This study holds significant implications for the eventual industrialization of bioethanol refinement.