Effect of alkali salt-coupled ball milling pretreatment of wheat straw on improving enzymatic hydrolysis and energy efficiency

Pretreatment of lignocellulosic biomass is crucial in producing fermentable sugars in a sustainable biorefinery. In this study, wheat straw was pretreated with a combination of ball milling (BM) and NaAlO2 particles (NaAlO2-BM) for enzymatic hydrolysis within a short hydrolysis period. The effects of energy consumption on modifications of physicochemical proprieties and energy efficiency were elucidated. NaAlO2-BM pretreatment decreased particle size rapidly to tissue scale in 10 min with energy consumption reduced by 0.5 times compared to BM pretreatment. NaAlO2-BM pretreated for 20 min achieved a glucose yield of 95.4% at a cellulase loading of 10 FPU/g dry substrate for 24 h enzymatic hydrolysis and provided the highest energy efficiency of 0.121 kg glucose/kWh, increasing by 1.1 times than BM pretreatment. Energy consumption showed a positive relationship with cellulose content while it negatively correlated with median particle size, cellulose crystallinity and energy efficiency. The combination of BM and NaAlO2 particles was demonstrated to be a promising pretreatment approach for glucose production and improving energy efficiency during hydrolysis of lignocellulose.