Feasibility of a facile butanol bioproduction using planetary mill pretreatment

Recent advances on physical technologies for the pretreatment of food waste and lignocellulosic residues

The complete deployment of a bio-based economy is essential to meet the United Nations' Sustainable Development Goals from the 2030 Agenda. In this context, food waste and lignocellulosic residues are considered low-cost feedstocks for obtaining industrially attractive products through biological processes. The effective conversion of these raw materials is, however, still challenging, since they are recalcitrant to bioprocessing and must be first treated to alter their physicochemical properties and ease the accessibility to their structural components. Among the full pallet of pretreatments, physical methods are recognised to have a high potential to transform food waste and lignocellulosic residues. This review provides a critical discussion about the recent advances on milling, extrusion, ultrasound, and microwave pretreatments. Their mechanisms and modes of application are analysed and the main drawbacks and limitations for their use at an industrial scale are discussed.

Feasibility of Continuous Pretreatment of Corn Stover: A Comparison of Three Commercially Available Continuous Pulverizing Devices

We determined the potential of three mechanical pulverizers—a continuous ball mill (CBM), an air classifier mill (ACM), and a high-speed mill (HSM)—in the continuous pretreatment of corn stover. The mean diameters of the pulverized biomasses were not significantly different in the three cases, and the glucose yields from the CBM-, ACM-, and HSM-pulverized samples were 29%, 49%, and 44%, respectively. The energy requirements and process capacities for the ACM and HSM were similar. We conclude that the ACM and HSM could be used in the continuous pretreatment of corn stover and would be useful in biofuel production.

Enhanced Enzymatic Hydrolysis of Rice Straw Pretreated by Oxidants Assisted with Photocatalysis Technology

This work evaluated the effectiveness of rice straw pretreatment using a TiO₂/UV system in the presence of oxidants. The effects of TiO₂ concentrations, pH and photocatalysis time were investigated. Inorganic oxidants including H₂O_2, K₂S₂O₈, and KIO₄ were added to further enhance the effect on enzymatic hydrolysis of rice straw. The TiO₂/UV/ H₂O₂ pretreatment showed a higher amount of released reducing sugar (8.88 ± 0.10 mg/mL, compared to 5.47 ± 0.03 mg/mL in untreated sample). Composition analyses of rice straw after the TiO₂/UV/H₂O₂ pretreatment showed partial lignin and hemicellulose removal. Moreover, structural features of untreated and pretreated rice straw were analyzed through FE-SEM, FT-IR, and XRD. This work suggests that H₂O₂ is an efficient addition for photocatalysis pretreatment of rice straw.