Synergistic Integration of Mechanical Densification and Ultra-Low-Dosage Fenton Oxidation Enables Efficient Deconstruction of Corn Stover and High-Titer Ethanol Production.

To reduce chemical consumption in lignocellulosic biorefinery, we developed a densification pretreatment using Fenton's reagent followed by autoclave treatment (DLCA(ft)). This method integrates mechanical densification with catalytic oxidation. It reduces chemical dosage to an ultra-low 0.0289 g/g biomass, far below that of conventional oxidative pretreatments. Multi-scale characterization revealed that this method effectively disrupted the lignin-carbohydrate matrix without severe delignification, significantly enhancing biomass porosity and enzymatic digestibility. Consequently, DLCA(ft) pretreated corn stover achieved exceptional enzymatic digestibility (>90% total sugar conversion) even at 35% (w/w) solid loading. Crucially, the minimal chemical usage suppressed the formation of many inhibitory degradation products, enabling direct fermentation to a high ethanol titer of 81.8 g/L without water washing or detoxification. DLCA(ft) pretreatment addressed critical barriers of high reagent cost and low working mass in traditional pretreatment systems, representing a significant step toward the industrial realization of lignocellulosic biorefinery.