Comparison of product distribution, content and fermentability of biomass in a hybrid thermochemical/biological processing platform

Abstract

Thermochemical processing is a promising method for the rapid depolymerization of biomass. This study investigated switchgrass, corn stover, red oak, hybrid poplar, and loblolly pine in terms of heteropolymer and elemental composition, and the distribution and composition of the fast pyrolysis products. Corn stover differed from other biomass types in that less of the biomass was recovered as sugar or phenolic oil (PO) and more of the biomass was recovered as bio-char and bio-gas. The sugar-rich aqueous stream recovered from the bio-oil heavy fraction was characterized in terms of sugar content and distribution, inhibitor content, and ability to support production of ethanol by Escherichia coli KO11+lgk as a model biorenewable product. Levoglucosan was the most abundant sugar from each type of biomass, followed by either xylose or cellobiosan. For hybrid poplar, cellobiosan accounted for 30 wt% of the total sugar pool. Each of the sugar streams also contained a variety of inhibitors, particularly 5hydroxymethylfurfural (5-HMF) and methylcyclopentenolone. Methylcyclpentenolone, maple lactone, was found to decrease the specific growth rate of E. coli by 50% when present at 0.72 wt%, indicating that it is less toxic than furfural, acetic acid and guaiacol. Sugars produced from switchgrass contained 4fold less contaminants on a per-sugar basis than those from poplar and pine. All of the sugar streams contained too many inhibitors to be used at an industrially feasible concentration without additional detoxification. The poplar-derived pyrolytic sugar syrup was particularly inhibitory, possibly due to the high abundance of aromatic hydrocarbons, such as xylenes, and anisoles.

Sterilisation of Wort from Sugarcane Molasses by Electron Beam for Bioethanol Production

“…According to Rasmussen et al (2014), the degradation of carbohydrates, especially D-glucose, D-xylose and L-arabinose can be related to the production of compounds such as phenolics. These compounds have been considered biocatalyst inhibitors (Chi et al 2019), and their gradual production according to e-beam dose increase was also observed in Lima et al (2016) study. But, in our work, the presence of phenolics did not inhibit yeast cell viability and biomass production (p>0.05) in any treatment during the fermentation (Table 3).…”

“…In our study, it was not observed formation and alteration in the concentration of the inhibitors avonoids, furfural and 5-HMF (p>0.05) in any condition of treatment evaluated (Table 1). Such compounds are generally produced from sugar degradation, especially in thermal conditions (Molins 2001, Eggleston and Amorim 2006, Chi et al 2019). However, it did not occur in this study, including in the steam treatment (T5).…”

Promoting microbial utilization of phenolic substrates from bio-oil

“…S1). Many of these compounds were also detected in the aqueous sugar wash solution produced in the same bio-oil recovery and processing framework [11].…”

“…Fast pyrolysis of biomass produces several product streams: a heavy ends stream which is rich in sugars and water-insoluble phenolics, bio-char which is collected via cyclones and can be used as a soil additive, and lastly, a light ends aqueous stream rich in acetate ( Fig. 1) [66,4,11]. The water-insoluble phenolic oil stream is mainly composed of lignin-derived products, including monophenols such as phenol and syringol, in addition to higher molecular weight phenolic oligomers [4], with its composition being impacted by the pyrolysis conditions [62].…”

Extrapolation of design strategies for lignocellulosic biomass conversion to the challenge of plastic waste

“…Biomass composition varies substantially according to species (Chi et al., 2019 ), but is also impacted by growth conditions (Dennison et al., 2019 ; Templeton et al., 2009 ) and storage conditions (Smith et al., 2020 ; Towey et al., 2019 ; Wendt & Zhao, 2020 ) of the harvested biomass. Similar to the challenge of contaminants in mixed plastic wastes, harvested biomass often contains sand and soil, the presence of which can negatively impact biomass hydrolysis, often requiring the addition of a process step for their removal (Horhammer et al., 2018 ).…”