Physical and chemical differences between one-stage and two-stage hydrothermal pretreated hardwood substrates for use in cellulosic ethanol production

Abstract

BackgroundThere are many different types of pretreatment carried out to prepare cellulosic substrates for fermentation. In this study, one- and two-stage hydrothermal pretreatment were carried out to determine their effects on subsequent fermentations. The two substrates were found to behave differently during fermentation. The two substrates were then characterized using physical and chemical parameters.ResultsThe one-stage substrate was found to have higher carbohydrate content and lower lignin content. It exhibited a higher level of viscosity, a larger settled volume, and a slower settling time than the two-stage substrate. It also showed higher polarity and reduced crystallinity. Glycome profiling showed physical differences between the two substrates, specifically pointing toward higher levels of pectin and hemicellulose in the one-stage substrate (MS1112) as compared to the two-stage substrate (MS1107).ConclusionsWe hypothesize that these physical and chemical differences between the substrates contribute to the differences seen during fermentation including: ethanol yield, ethanol titer, fermentation rate, fermentation completion time, mixing, and substrate solubilization. These findings can be used in optimizing pretreatment parameters to maximize ethanol conversion and overall process yield for hardwood substrates.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-016-0446-9) contains supplementary material, which is available to authorized users.

Integral valorization of vine pruning residue by sequential autohydrolysis stages

“…Few works have reported the effect of autohydrolysis in two stages on lignocellulosic biomass being the results obtained in this work favorably compared with the literature (Park et al, 2016;Guilliams et al, 2016). Recently, this strategy has been employed to reduce the inhibitor loading in wheat straw and hardwoods hydrolysates (Min et al, 2015;Park et al, 2016).…”

“…In this sense, one of the autohydrolysis limitations is the difficulty to attain an optimal condition for oligosaccharides manufacturing and suitable saccharification of cellulose into glucose for fuel production (Romaní et al, 2010). Typically, cellulose is more prone to saccharification after harsh conditions of pretreatment while in these severe conditions the xylose and xylooligosaccharides are degraded into sugars and/or inhibitors compounds such as furfural (Guilliams et al, 2016). Thus, the strategy employed for this two-target goal usually includes the use of two treatments (such as an autohydrolysis combined with a delignification process) (Romaní et al, 2011(Romaní et al, , 2016.…”

Bioethanol Production from Selected Species of Astera Plants by Simultaneous Saccharification and Fermentation using Dilute Acid and Alkaline Extraction Pretreatment Methods

“…Each pretreatment process has a specific effect on the cellulose, hemicellulose and lignin fraction. Physical and chemical differences between the substrates causes differences during fermentation including: ethanol yield, ethanol titer, fermentation rate, fermentation completion time, mixing, and substrate solubilization [17] .…”

Methane production in response to sulfuric acid and hydrogen peroxide assisted hydrothermal pretreatment of sugarcane bagasse

“…Hydrothermal pretreatment is carried out in three types of reactors; cocurrent (biomass and liquid water cooked together), counter current (movement of biomass and liquid water in the opposite direction), and flow-through reactors (hot water flow over a stationary bed of biomass) (Liu and Wyman, 2005). Hydrothermal pretreatment combat against recalcitrance of lignocellulosic biomass under heat and pressure at different reactor configurations to break strong bonding between carbohydrate-lignin matrix (Guilliams et al, 2016).…”