Effects of mechanical pretreatments on enzymatic hydrolysis of mixed lignocellulosic substrates for biorefineries

The enzymatic hydrolysis of lignocellulosic biomass into fermentable sugars remains a critical challenge for producing bio-based products due to complexity and recalcitrance of the biomass. The effects of mechanical pretreatments (i.e., wet grinding for corncob residues and PFI refining for wood fibers) on the enzymatic hydrolysis of mixed substrates of corncob residues (CRs) and wood fibers (WFs) were investigated. The results showed that the applied combined mechanical pretreatments noticeably enhanced the enzymatic digestibility of the mixed substrates. A 99.8% conversion yield of cellulose to glucose and 19.2 g/L glucose concentration were obtained when the mixed substrates (composed of the refined WFs and the ground CRs) were enzymatically hydrolyzed for 46 h. The improvements, including swelling ability, specific surface area, and morphology, were mainly attributed to the combined mechanical pretreatments.