Use of mechanical refining to improve the production of low-cost sugars from lignocellulosic biomass

Abstract

Mechanical refining is widely used in the pulp and paper industry to enhance the end-use properties of products by creating external fibrillation and internal delamination. This technology can be directly applied to biochemical conversion processes. By implementing mechanical refining technology, biomass recalcitrance to enzyme hydrolysis can be overcome and carbohydrate conversion can be enhanced with commercially attractive levels of enzymes. In addition, chemical and thermal pretreatment severity can be reduced to achieve the same level of carbohydrate conversion, which reduces pretreatment cost and results in lower concentrations of inhibitors. Refining is versatile and a commercially proven technology that can be operated at process flows of ∼ 1500 dry tons per day of biomass. This paper reviews the utilization of mechanical refining in the pulp and paper industry and summarizes the recent development in applications for biochemical conversion, which potentially make an overall biorefinery process more economically viable.

Optimization of Pilot Scale Mechanical Disk Refining for Improvements in Enzymatic Digestibility of Pretreated Hardwood Lignocellulosics

“…Therefore, all discussions in the present article are related to mechanical refining as a post-treatment to traditional woody biomass pretreatment. The use of mechanical refining in a lignocellulosic biorefinery has also been studied for many different biomass and pretreatment types (Park et al 2016). Sulfur dioxide free steam pretreated hybrid poplar achieved a 32% improvement in hydrolysis efficiency after 30 min of low consistency valley beater refining, comparable to the high severity steam plus sulfur dioxide treatments (Dou et al 2016).…”

Zymomonas mobilis as a model system for production of biofuels and biochemicals

“…DA pretreatment is one of the most cost effective methods reported and has been extensively studied (Harmsen et al ., ). However, inhibitory compounds formed during this process, including furfural, hydroxymethylfurfural (HMF), formic acid, levulinic acids, acetic acid, vanillin and phenolic aldehydes, have negative effects on cellular growth, metabolism and the production of desired products (Delgenes et al ., ; Gu et al ., ; Yi et al ., ; Park et al ., ). Detailed work has been conducted to investigate the composition of hydrolysate to find inhibitory compounds, and a high‐throughput biological growth assay has been developed to obtain detailed inhibitory kinetics for individual compounds or synergistic combinations of these compounds (Franden et al ., , ; Wang et al ., ; Yi et al ., ).…”

Integrating a Biorefinery into an Operating Kraft Mill

“…Methods to couple pulverization with enzymatic hydrolysis in a continuous stream at high solids was proposed to improve cost and streamline the process. The use of conventional mechanical refining was examined as an alternative to chemical pretreatments for hydrolysis of wood to sugars with lower production of fermentation inhibitors (Jones et al 2013;Dou et al 2016;Park et al 2016). Refining coupled with mild pretreatment (steam or dilute acid) reduced overall conversion costs and the level of fermentation inhibitors at equal sugar yield.…”