Unlocking Highly Digestible Lignocellulosic Biomass and High-Titer Ethanol/Lactic Acid Production via Densification Pretreatment Using Sulfuric Acid and Hydrogen Peroxide

The development of efficient and sustainable pretreatment technologies is crucial for lignocellulosic biomass valorization. This study developed a novel method, “densifying lignocellulosic biomass using sulfuric acid and hydrogen peroxide followed by autoclave treatment (DLCA­(sa-hp))” to overcome the limitations of traditional acidic pretreatment, particularly their insufficient improvement in cellulose digestibility and fermentability. DLCA­(sa-hp) pretreatment performed under solid-state conditions with a low reagent dosage of only 0.075 g/g biomass offers advantages of high working mass and low chemical use versus traditional methods, enabling efficient deconstruction of hemicellulose and cellulose. DLCA­(sa-hp) pretreated biomass achieved outstanding enzymatic digestibility, with glucan and xylan conversions reaching 91.9% and 91.6%, respectively. High solid-loading enzymatic hydrolysis (35% (w/w)) yielded fermentable sugar concentrations exceeding 210 g/L, with sugar conversions remaining above 90%. The resulting hydrolysate demonstrated excellent fermentability, yielding maximum concentrations of 95.0 g/L ethanol and 223.4 g/L lactic acid. Techno-economic analysis confirmed the huge economic potential of this method in cellulosic ethanol production. Hence, DLCA­(sa-hp) pretreatment greatly enhances digestibility and microbial utilization efficiency of lignocellulosic polysaccharides, offering a promising, environmentally friendly strategy for advancing lignocellulosic biorefinery.