Cellulosic Ethanol Production Research Articles

Novel Heat-Integrated Hybrid Distillation and Adsorption Process for Coproduction of Cellulosic Ethanol, Heat, and Electricity from Actual Lignocellulosic Fermentation Broth

Cellulosic ethanol (CE) can not only be produced from a nonedible, cheap, and abundant lignocellulose feedstock but also can reduce carbon footprint significantly compared to starch ethanol. Despite great stimulation worldwide, CE production has not yet commercialized because of the complexity of lignocellulose. Therefore, intensive research and development are needed to improve CE technologies. In this study, a cost-efficient and sustainable design was proposed for the coproduction of CE, heat, and electricity from the actual lignocellulosic fermentation broth. First, a conventional coproduction process of CE, heat, and electricity based on hybrid distillation and adsorption (HDA) was simulated and optimized. Subsequently, various heat integrated (HI) techniques such as heat pump (HP), multi-effect distillation (MED), and combined HP-MED were evaluated to improve the CE process. The combined heat and power (CHP) process that utilized the combustible solids of the beer stillage was designed and integrated with the CE process. Structural alternatives were assessed for both economic and environmental impacts. The results show that the proposed HI-HDA process can save 36.9% and 33.6% of total annual costs and carbon footprint, respectively, compared to the conventional CE process. In the proposed HI-HDA coproduction process, the CE recovery process can be self-efficient in energy and the CHP can generate 12.0% more electricity than that in the conventional coproduction process.

Elucidating the multifunctional role of the cell wall components in the maize exploitation

BackgroundBesides the use of maize grain as food and feed, maize stover can be a profitable by-product for cellulosic ethanol production, whereas the whole plant can be used for silage production. However, yield is reduced by pest damages, stem corn borers being one of the most important yield constraints. Overall, cell wall composition is key in determining the quality of maize biomass, as well as pest resistance. This study aims to evaluate the composition of the four cell wall fractions (cellulose, hemicellulose, lignin and hydroxycinnamates) in diverse maize genotypes and to understand how this composition influences the resistance to pests, ethanol capacity and digestibility.ResultsThe following results can be highlighted: (i) pests’ resistant materials may show cell walls with low p-coumaric acid and low hemicellulose content; (ii) inbred lines showing cell walls with high cellulose content and high diferulate cross-linking may present higher performance for ethanol production; (iii) and inbreds with enhanced digestibility may have cell walls poor in neutral detergent fibre and diferulates, combined with a lignin polymer composition richer in G subunits.ConclusionsResults evidence that there is no maize cell wall ideotype among the tested for optimal performance for various uses, and maize plants should be specifically bred for each particular application.

Production of Cellulosic Ethanol from Alkali-Treated Wheat Straw Using P-SSF Process and Bioconversion of Hemicellulosic Fraction into High- Value Products

Background: Lignocellulosic biomass is an attractive resource for the production of ethanol because of its abundance and lower cost. The economics of lignocellulosic ethanol production can be improved by enhancing the ethanol titres along with the utilisation of waste generated during the bioconversion process. Objective: The present study was aimed at the development of a bioconversion process for producing a high concentration of ethanol from alkali-treated cellulose-rich wheat straw (WS) and utilization of unused hemicellulosic fraction into value added products. Methods: WS was subjected to microwave-assisted alkali (MAA) treatment. Scanning electron microscopy and Fourier transform infrared spectroscopy were used to analyse structural changes in untreated and pretreated WS. Bioethanol production from pretreated WS was carried out by pre hydrolysis and simultaneous saccharification and fermentation (P-SSF) process using newly isolated Saccharomyces cerevisisae SM1. Liquid fraction generated during pretreatment was utilised for xylooligosaccharides (XOS) production using indigenously produced endoxylanase. Results: MAA treatment of WS was successful in enriching the cellulose content of WS by solubilizing hemicellulose and lignin. Ethanol fermentation by the P-SSF method leads to the high concentration of ethanol (42.10±1.15 g/L) in 48 h. Ethanol productivity and yield were 0.88 g/L/h and 69.14%, respectively. It can be predicted that 7.143 tons of raw WS may be required to produce 1 ton of ethanol, and for additional revenue, 191.93 kg xylitol and 263.58 kg XOS (DP2 - DP5) can also be produced simultaneously. Conclusion: The study has demonstrated the feasibility of a bio-refinery process for the production of value-added compounds in addition to high ethanol yields.

Process optimization for deep eutectic solvent pretreatment and enzymatic hydrolysis of sugar cane bagasse for cellulosic ethanol fermentation

This study investigated cellulosic ethanol production from sugar cane bagasse (SCB) pretreated by triethylbenzyl ammonium chloride/lactic acid (TEBAC/LA) deep eutectic solvent (DES). The results showed that the pretreatment of SCB with TEBAC/LA DES at 120 °C for 4 h with 1:15 (solid to liquid ratio) resulted in the best cellulose digestibility (88.23 ± 1.24%), which was approximately 228% higher than that of untreated SCB. Furthermore, the maximum cellulosic ethanol concentration of 16.84 g/L was achieved using glucose (36.06 g/L) and xylose (7.36 g/L). Moreover, the ethanol productivity and yield were 0.70 g/(L·h) and 0.42 g/g fermentable sugar, respectively. The efficient bioconversion was ascribed to the remarkable delignification (88.72 ± 1.63%), xylan removal (73.93 ± 0.17%), along with optimum cellulose recovery (95.89 ± 1.54%). Importantly, the enzymatic hydrolysis digestibility remained unchanged after 5 times DES recycling process. Overall, it also provided an insight into the efficient SCB biorefinery of DES systems.

Comparison of Low-Temperature Alkali/Urea Pretreatments for Ethanol Production from Wheat Straw

NaOH/urea (NU) pretreatment at lower than 0 °C has been frequently applied for improving bio-conversion of lignocellulose, but the wastewater generated from the pretreatment process is hard to dispose. KOH/urea (KU) pretreatment for enhancing bioconversion of lignocellulose has recently attracted researchers’ attention due to the recycling of wastewater for facilitating crops’ growth. This study compared the effects of NU and KU pretreatments at cold conditions on the enzymatic hydrolysis and bioethanol yield from wheat straw (WS). By using response surface methodology an optimal pretreatment with an equal ratio of alkali/urea (4% w/v) at −20 °C for 3 h was established. The enzymatic hydrolysis of KU-treated WS was 81.17%, which was similar to that of NU-treated WS (83.72%) under the same condition. It means that KU pretreatment has equal ability to NU pretreatment to improve enzymatic saccharification of lignocellulose. KU pretreatment has the promising potential to replace NU pretreatment for facilitating bioconversion of lignocellulose in cold conditions due to the clean way to recycle its wastewater as fertilizer for crop growth. Hence, KU pretreatment combined with enzymatic hydrolysis and fermentation could be a promising green way to cellulosic ethanol production with zero waste emission.

Mixed fermentation of corn and pretreated corn stover for fuel ethanol production

AbstractBackground and objectivesFuel ethanol is almost exclusively produced from corn with minor contributions from other cereal grains. Cellulosic ethanol production has significant potential as well as serious limitations. This study proposed that pretreated corn stover could be simultaneously converted and fermented with corn in existing ethanol facilities.FindingsMixed fermentation ethanol yields increased significantly relative to the control fermentations. Incorporation of 5% pretreated corn stover increased ethanol yields by 12.7% with 10% corn mash and 11.9% with 20% corn mash over corn only control fermentations. Using 20% corn, residual xylose and arabinose were 0.072 and 0.023 grams/gram biomass, respectively, indicating addition ethanol potential with a C5 fermenting yeast. DDGS color and lipid contents were negatively impacted; however, the nutrient value of the corn portion is unlikely to be altered.ConclusionsDirect incorporation of pretreated corn stover into the corn ethanol process can be done with little or no reduction in corn or stover conversion efficiency.Significance and noveltyThis study demonstrates clearly that pretreated biomass can be efficiently co‐fermented with corn to produce cellulosic ethanol in yields approximating those from biomass alone and eliminates many of the significant economic and processing issues that stand‐alone cellulosic ethanol facilities face.

Estimation of Crystalline Cellulose Content of Plant Biomass using the Updegraff Method.

Cellulose is the most abundant polymer on Earth generated by photosynthesis and the main load-bearing component of cell walls. The cell wall plays a significant role in plant growth and development by providing strength, rigidity, rate and direction of cell growth, cell shape maintenance, and protection from biotic and abiotic stressors. The cell wall is primarily composed of cellulose, lignin, hemicellulose and pectin. Recently plant cell walls have been targeted for the second-generation biofuel and bioenergy production. Specifically, the cellulose component of the plant cell wall is used for the production of cellulosic ethanol. Estimation of cellulose content of biomass is critical for fundamental and applied cell wall research. The Updegraff method is simple, robust, and the most widely used method for the estimation of crystalline cellulose content of plant biomass. The alcohol insoluble crude cell wall fraction upon treatment with Updegraff reagent eliminates the hemicellulose and lignin fractions. Later, the Updegraff reagent resistant cellulose fraction is subjected to sulfuric acid treatment to hydrolyze the cellulose homopolymer into monomeric glucose units. A regression line is developed using various concentrations of glucose and used to estimate the amount of the glucose released upon cellulose hydrolysis in the experimental samples. Finally, the cellulose content is estimated based on the amount of glucose monomers by colorimetric anthrone assay.

Production and Application of Lignin-Based Chemicals and Materials in the Cellulosic Ethanol Production: An Overview on Lignin Closed-Loop Biorefinery Approaches

Lignocellulosic biomass is the most abundant biological resource on the planet and has been extensively researched to produce cellulosic ethanol. However, there is a consensus that the presence of lignin hinders the biomass conversion. Lignin is often considered a villain in cellulosic ethanol production studies due to its adverse effects on cellulases and yeasts. Despite this, recent studies indicate that lignins can be transformed into useful inputs to produce cellulosic ethanol. These approaches aim to establish closed-loop biorefineries to improve economic metrics and reduce the environmental impact due to the substitution of products based on fossil sources. The present review addresses the successful cases in transforming lignin into chemicals and materials to increase cellulosic ethanol titers. A contextualization was first carried out, considering aspects of biomass characteristics and lignin valorization. The impact of lignin-based chemicals and materials in the pretreatment, detoxification, and enzymatic hydrolysis steps was discussed in detail. Economic aspects and future perspectives were also included in this review. These reports open a new point of view on lignin valorization and its integration with the cellulosic ethanol production chain.

Rheological characterization of ball-milled corn stover with different fragmentation scales at high-solids loading

A fundamental understanding of the rheology of high-solids lignocellulose slurry is essential for the design of efficient cellulosic ethanol production processes and bioreactors. Here we analyzed the rheological properties of high-solids corn stover slurries with particles size ranged from tissue scale to cellular scale. Results showed that the apparent viscosity/yield stress decreased with the increase of free water amount and the decrease of particle size, and the quantitative relationships among them were obtained. A 300-fold and 130-fold decrease in apparent viscosity and yield stress (30 % solids loading) were observed when the corn stover was reduced to cellular scale (≤ 50 μm). Further analysis revealed that size reduction to tissue scale reduces the viscosity and yield stress by alleviating the interactions between particles, while size reduction to cellular scale not only weakens the particle interactions, but also increases free water amount due to destruction of cell lumen, thus greatly enhances the rheological behaviors. And this improvement is undoubtedly of great significance for inter-unit operation and mixing energy saving.

Technology valuation of cellulosic ethanol production by Kluyveromyces marxianus CCT 7735 from sweet sorghum bagasse at elevated temperatures

Technology valuation of cellulosic ethanol production by Kluyveromyces marxianus CCT 7735 based on the concepts of circular economy was investigated. After an acid-base pretreatment followed by saccharification at 50 °C for 72 h, the sweet sorghum hydrolysate was used to produce ethanol at three temperatures: 37, 42, and 45 °C. About 17.83 g/L of cellulosic ethanol was reached at 42 °C in 24 h, with a yield of 2769.8 L/hasorghum, almost double that obtained for corn straw. This was the best cellulosic ethanol production from sweet sorghum bagasse achieved by K. marxianus strain and, therefore, it was used in the technology valuation. This analysis was carried out through the application of the profit equation, in which the revenue corresponded to ethanol sales in the global market in 2020, and the costs were defined by the activity-based costing method. An integration between 1G and 2G ethanol production, without mixing material streams, was considered to improve the technology valuation analysis. As a result, the equivalent to 17.2% of the profit obtained with the sugarcane juice ethanol was achieved for the sweet sorghum bagasse. Therefore, the technology valuation indicated the potential of sweet sorghum bagasse in the biorefinery ethanol production.

Microwave-assisted hydrotropic pretreatment as a new and highly efficient way to cellulosic ethanol production from maize distillery stillage

Aim of the study was to assess the suitability of the combined use of microwave radiation and sodium cumene sulfonate under optimized process conditions for the preparation of maize stillage biomass as a raw material for the production of cellulosic ethanol. The key parameter guaranteeing a high level of lignin removal from biomass (ca. 44%) was concentration of hydrotrope. Even at high biomass concentration (16% w/v) and a cellulase enzyme dose of about 4 filter-paper units/g, maize stillage biomass subjected to microwave-assisted hydrotropic pretreatment was highly susceptible to enzymatic degradation, which resulted in 80% hydrolysis yield. It is possible to obtain a fermentation medium with a very high glucose concentration (up to 80 g/L), without fermentation inhibitors and, as a consequence, to reach a very high level of sugar conversion to ethanol (concentration above 40 g/L), even as much as 95% of theoretical yield. Microwave hydrotropic treatment with sodium cumene sulfonate is a very effective way to prepare waste maize stillage biomass for the production of cellulosic ethanol. The degradation of the lignocellulose structure by the simultaneous use of microwaves and hydrotropes ensured a high degree of conversion of structural polysaccharides to bioethanol. The method provides a high level of enzymatic degradation of cellulose, leading to a medium with high content of released sugars suitable for bioconversion, which is in line with assumptions of the second-generation ethanol production technology.Key points• Microwave-assisted hydrotropic pretreatment is a new way to cellulosic ethanol production.• Microwave-assisted hydrotropic delignification removes 44% of lignin from biomass.• No fermentation inhibitors are obtained after microwave-assisted hydrotropic pretreatment.• High ethanol concentration (above 40 g/L) and fermentation yield (95% of theoretical yield) from biomass after microwave-assisted hydrotropic pretreatment.

Production of bio-ethanol by consecutive hydrogenolysis of corn-stalk cellulose

Current bio-ethanol production entails the enzymatic depolymerization of cellulose, but this process shows low efficiency and poor economy. In this work, we developed a consecutive aqueous hydrogenolysis process for the conversion of corn-stalk cellulose to produce a relatively high concentration of bio-ethanol (6.1 wt%) without humin formation. A high yield of cellulose (ca. 50 wt%) is extracted from corn stalk using a green solvent (80 wt% 1,4-butanediol) without destroying the structure of the lignin. The first hydrothermal hydrogenolysis step uses a Ni–WOx/SiO2 catalyst to convert the high cumulative concentration of cellulose (30 wt%) into a polyol mixture with a 56.5 C% yield of ethylene glycol (EG). The original polyol mixture is then subjected to subsequent selective aqueous-phase hydrogenolysis of the C–O bond to produce bioethanol (75% conversion, 84 C% selectivity) over the modified hydrothermally stable Cu catalysts. The added Ni component favors the good dispersion of Cu nanoparticles, and the incorporated Au3+ helps to stabilize the active Cu0-Cu+ species. This multi-functional catalytic process provides an economically competitive route for the production of cellulosic ethanol from raw lignocellulose.

CAMP activates calcium signalling via phospholipase C to regulate cellulase production in the filamentous fungus Trichoderma reesei

BackgroundThe filamentous fungus Trichoderma reesei is one of the best producers of cellulase and has been widely studied for the production of cellulosic ethanol and bio-based products. We previously reported that Mn2+ and N,N-dimethylformamide (DMF) can stimulate cellulase overexpression via Ca2+ bursts and calcium signalling in T. reesei under cellulase-inducing conditions. To further understand the regulatory networks involved in cellulase overexpression in T. reesei, we characterised the Mn2+/DMF-induced calcium signalling pathway involved in the stimulation of cellulase overexpression.ResultsWe found that Mn2+/DMF stimulation significantly increased the intracellular levels of cAMP in an adenylate cyclase (ACY1)-dependent manner. Deletion of acy1 confirmed that cAMP is crucial for the Mn2+/DMF-stimulated cellulase overexpression in T. reesei. We further revealed that cAMP elevation induces a cytosolic Ca2+ burst, thereby initiating the Ca2+ signal transduction pathway in T. reesei, and that cAMP signalling causes the Ca2+ signalling pathway to regulate cellulase production in T. reesei. Furthermore, using a phospholipase C encoding gene plc-e deletion strain, we showed that the plc-e gene is vital for cellulase overexpression in response to stimulation by both Mn2+ and DMF, and that cAMP induces a Ca2+ burst through PLC-E.ConclusionsThe findings of this study reveal the presence of a signal transduction pathway in which Mn2+/DMF stimulation produces cAMP. Increase in the levels of cAMP activates the calcium signalling pathway via phospholipase C to regulate cellulase overexpression under cellulase-inducing conditions. These findings provide insights into the molecular mechanism of the cAMP–PLC–calcium signalling pathway underlying cellulase expression in T. reesei and highlight the potential applications of signal transduction in the regulation of gene expression in fungi.

Increasing cellulosic ethanol production by enhancing phenolic tolerance of Zymomonas mobilis in adaptive evolution

Cellulosic ethanol fermentability of ethanologenic strain Zymomonas mobilis is severely inhibited by phenolic aldehydes generated from lignocellulose pretreatment. Here, a 198 days’ laboratory adaptive evolution of Z. mobilis 8b in corn stover hydrolysate was conducted to increase its phenolic aldehydes tolerance and ethanol fermentability. The obtained Z. mobilis Z198 demonstrated a significantly improved conversion of the most toxic phenolic aldehyde (vanillin) by 6.3-fold and cellulosic ethanol production by 21.6%. The transcriptional analysis using qRT-PCR revealed that the gene ZMO3_RS07160 encoding SDR family oxidoreductase in Z. mobilis Z198 was significantly up-regulated by 11.7-fold. The overexpression of ZMO3_RS07160 in the parental Z. mobilis increased the ethanol fermentability to that of the adaptively evolved strain Z. mobilis Z198. This study provided a practical method to obtain a robust cellulosic ethanol fermenting strain, and a candidate gene for synthetic biology of biorefinery strains with strong phenolic aldehydes tolerance.

Production, immobilization and characterization of beta-glucosidase for application in cellulose degradation from a novel Aspergillus versicolor

Beta-glucosidase (EC 3.2.1.21) catalyzes the hydrolysis of cellobiose and cellooligosaccharides containing (1 → 4)-beta-glycosidic bonds to glucose, which is crucial in cellulosic ethanol production. In this study, Aspergillus versicolor, a novel highly productive beta-glucosidase strain, was first isolated from Camptotheca acuminata seeds. The highest beta-glucosidase activity with 812.86 U/mL was obtained by using the response surface methodology, and a 14.4-fold has increased compared to the control. The beta-glucosidase was then purified to homogeneity with recovery yield and specific activity of 25.98% and 499.15 U/mg, respectively. To enhance its stability and recyclability, the purified beta-glucosidase was first immobilized onto magnetic MnO2 by electrostatic adsorption. The immobilized materials were characterized by FR-IT, TEM and FE-SEM. Compared with the free beta-glucosidase, the immobilized enzyme exhibited enhanced thermal stability (1.5-fold raise in half-life at 50 °C), and reusability (holding over 60% activity after eight cycles), besides, the optimum pH has increased to 6.0. Substrate specificity research suggested that the enzyme had high hydrolytic activity on cellobiose. It also had a hydrolysis effect on (1 → 3) and (1 → 6)-beta-glycosidic linkages. Application trials in cellulose hydrolysis revealed that the immobilized enzyme was comparatively more effective. Our results suggested this novel immobilized beta-glucosidase makes a promising alternative for the cellulosic ethanol production.

Ethanol Production from Wheat Straw Hydrolysate by Issatchenkia Orientalis Isolated from Waste Cooking Oil

The interest in using non-conventional yeasts to produce value-added compounds from low cost substrates, such as lignocellulosic materials, has increased in recent years. Setting out to discover novel microbial strains that can be used in biorefineries, an Issatchenkia orientalis strain was isolated from waste cooking oil (WCO) and its capability to produce ethanol from wheat straw hydrolysate (WSHL) was analyzed. As with previously isolated I. orientalis strains, WCO-isolated I. orientalis KJ27-7 is thermotolerant. It grows well at elevated temperatures up to 42 °C. Furthermore, spot drop tests showed that it is tolerant to various chemical fermentation inhibitors that are derived from the pre-treatment of lignocellulosic materials. I. orientalis KJ27-7 is particularly tolerant to acetic acid (up to 75 mM) and tolerates 10 mM formic acid, 5 mM furfural and 10 mM hydroxymethylfurfural. Important for biotechnological cellulosic ethanol production, I. orientalis KJ27-7 grows well on plates containing up to 10% ethanol and media containing up to 90% WSHL. As observed in shake flask fermentations, the specific ethanol productivity correlates with WSHL concentrations. In 90% WSHL media, I. orientalis KJ27-7 produced 10.3 g L−1 ethanol within 24 h. This corresponds to a product yield of 0.50 g g−1 glucose (97% of the theoretical maximum) and a volumetric productivity of 0.43 g L−1 h−1. Therefore, I. orientalis KJ27-7 is an efficient producer of lignocellulosic ethanol from WSHL.

Characterization of biomass-degrading enzymes using neutron diffraction and scattering

Efficient enzymatic degradation of cellulose is essential to the low-cost production of cellulosic ethanol and high-value-added chemicals. Fungal lytic polysaccharide monooxygenases (LPMOs), which ...

Furfural production from sugarcane bagasse along with co-production of ethanol from furfural residues

Cellulosic ethanol production from non-detoxified furfural residues produced at different operating conditions from sugarcane bagasse was investigated. Simultaneous saccharification and fermentation (SSF) technique and preconditioned industrial strains of Saccharomyces cerevisiae, i.e., EthanolRed® and CelluX™4, were used for fermentation. The highest furfural yield of 69% (11.44 g/100 g of dry bagasse) was achieved at 170 °C and 0.5 wt.% H2SO4 (170–200 °C and 0–1 wt.% H2SO4), with corresponding ethanol yields of 77–95% (9.57–11.58 g/100 g of dry bagasse). The mass of ethanol produced reflected conversion of about 50% of cellulose in raw biomass due to cellulose degradation during furfural production. No production conditions could be found where both furfural and ethanol yields were maximized, indicating an unavoidable compromise between the two co-products. Furfural production conditions that provided an acceptable compromise between furfural and ethanol during co-production from sugarcane bagasse were 170 °C and 0.25 wt.% H2SO4, resulting in furfural mass of 7.64 g/100 g of dry bagasse and ethanol mass of 9.86 and 10.91 g/100 g of dry bagasse when using EthanolRed® and CelluX™4, respectively.

The known unknowns in lignin biosynthesis and its engineering to improve lignocellulosic saccharification efficiency

Biofuels produced from lignocellulosic biomass provide energy security and reduce greenhouse gas emissions with positive impacts on sustainability. Lignocellulose byproducts are expected to impact the production of cellulosic ethanol. However, lignin is a major factor imposing biomass recalcitrance to saccharification. Although structural phenolics can be removed from lignocellulosic biomass, physical and chemical pretreatments are expensive. In turn, the structure and composition of lignin is very flexible. Up- and downregulation of genes and, thereby, enzymes involved in core and non-core lignin biosynthesis can reduce lignin content and improve biomass saccharification. Alternatively, insertion of heterologous genes to the phenylpropanoid pathway may lead to the incorporation of alternative monomers into lignin, creating desirable properties and preserving the biological roles of lignin with a positive effect on saccharification. Studies reporting the effect of fine regulation on lignin structures are mapping how plants can be transformed to enhance saccharification while preserving productivity. Based on these findings and events, this review updates the state-of-art changes in lignin biosynthesis to improve saccharification efficiency. The main findings reported over the last decade were summarized to permit researchers an overview of this relevant scientific subject.

Improving cellulosic ethanol production using ozonolysis and acid as a sugarcane biomass pretreatment in mild conditions

The efficiency of unpressurized ozonolysis (O) and acid washing (A) was investigated as a simple pretreatment procedure to depolymerize sugarcane biomass for posterior enzymatic hydrolysis and alcoholic fermentation to improve cellulosic ethanol production. The fiber chemical compositional analyses showed that the ozonolysis reduces the lignin content by 25%. High-performance anion-exchange chromatography (HPAEC-PAD) analysis showed that the loss of glucose during treatment was less than 1.5%. After enzymatic hydrolysis, the maximum glucose and xylose yield (310 ± 2 and 122 ± 3 mg g−1, respectively) were achieved from the OA treatment sequence and the fermentation yield was three times more ethanol than the yield from untreated bagasse. This simple treatment may be an alternative for improving cellulosic ethanol production using a mild-operational strategy.