Co-production of biofuels and value-added compounds from industrial Eucalyptus globulus bark residues using hydrothermal treatment

Abstract

In this work, hydrothermal treatment was assessed for the fractionation of industrial Eucalyptus globulus bark residue (EBR) to obtain biofuels and value-added compounds (such as oligosaccharides and phenolic compounds) in separated streams. Hydrothermal treatment was evaluated under non-isothermal regimen in the range of maximum temperature (T max) of 177-228 • C or severities (S 0) between 2.76 and 4.25. The highest oligosaccharides concentration (17.5 g/L) was achieved at S 0 of 3.69, corresponding to hemicellulose recovery of 77.30%. Under all severities evaluated in this work, over 90.94% and 84.17% of cellulose and lignin remained in the solid phase, respectively. The increase of S 0 improved 4.38-fold the enzymatic saccharification of cellulose, the highest glucose yield (84%) being achieved at S 0 of 4.04. Considering the maximal recovery of polysaccharides as glucose and oligosaccharides from the liquid and solid phases, S 0 of 4.04 was selected for bioethanol production using high solid loadings and following different strategies (simultaneous saccharification and fermentation-SSF and pre-saccharification and simultaneous saccharification and fermentation-PSSF). The utilization of 15% hydrothermally pretreated EBR without nutrient supplementation resulted in 26 g/L of ethanol, independently of the strategy used. An increase up to 17.5% solids and employing nutrient supplementation enabled the production of 38 g/L (or 4.8% v/v) of ethanol by PSSF.

Immobilization and Application of the Recombinant Xylanase GH10 of Malbranchea pulchella in the Production of Xylooligosaccharides from Hydrothermal Liquor of the Eucalyptus (Eucalyptus grandis) Wood Chips

“…As shown in Table 3 , the main sugars-derived components found in raw EWC were cellulose (33.4%) and xylan (14.8%), representing approximately 50% of EWC’s total composition ( Table 3 ). This result is according to previous chemical composition reported for E. grandis residues and other species of Eucalyptus , such as Eucalyptus nitens [ 54 ] and Eucalyptus globulus [ 55 , 56 ], which also described this feedstock as successful in the bioethanol production.…”

“…Eucalyptus spp. are fast-growing hardwood used mainly in the production of cellulose and paper, generating many rich-cellulose residues [ 54 , 55 ], which classifies it as a promising feedstock for bioethanol production and its derivates [ 55 , 56 ]. In the present work, Eucalyptus grandis wood chips (EWC) were used, and the chemical composition of raw material was performed ( Table 3 ).…”

“…LCM pretreatment is crucial to disrupting the lignocellulosic matrix and increasing hemicellulose sugar recovery, allowing higher cellulose accessibility and yields of fermentable sugars [ 57 ]. Liquid hot water (LHW) has become very popular in biorefinery since it only uses water at elevated temperatures and pressure [ 47 , 55 , 57 ]. Thus, the use of LHW in EWC was proposed as the first step to solubilize hemicelluloses, aiming to utilize and valorize EWC.…”

Strategies towards Reduction of Cellulases Consumption: Debottlenecking the Economics of Lignocellulosics Valorization Processes

“…In contrast to that, increased attention has been given to a new promising source of sugars that could also be biologically converted into biofuels or other chemicals [5,6],…”

“…In contrast to that, increased attention has been given to a new promising source of sugars that could also be biologically converted into biofuels or other chemicals [5,6], designated as lignocellulosic materials (LCMs). Lignocellulosic materials are theoretically unlimited, cheaper and may not compete with food crops [7].…”