Pretreatment Of Lignocellulosic Biomass Research Articles

Influence of alkaline and oxidative pre-treatment of waste corn cobs on biohydrogen generation efficiency via dark fermentation

Stages of waste corn cobs processing leading to the production of biohydrogen via dark fermentation are presented and discussed in this paper. Firstly, the effects of pre-treatment conditions i.e. alkaline, alkaline-oxidizing and Fenton oxidizing pre-treatment of lignocellulosic biomass on the removal of lignin were examined. The solid residue obtained in the first stage was subjected to saccharification by means of enzymatic hydrolysis. The composition of enzymatic hydrolysates and fermentation broths were investigated in order to determine the content of sugars as well as phenolic compounds and fermentation broth composition containing organic acids. The dark fermentation process of the obtained hydrolysates was carried using mixed wastewater sludge from the municipal sewage treatment plant. The highest hydrogen production was obtained for alkaline pre-treated hydrolysates. The effects of investigated chemical pre-treatment methods were discussed in terms of the obtained saccharification efficiency and composition of the gas phase formed during the fermentation, and the composition of fermentation broth.

Organosolv pre-treatment of groundnut (Arachis hypogaea) shell and its upshot

Pre-treatment of lignocellulosic biomass is an inevitable step toward value-added green chemicals. There are various modes of pre-treatment method that exist with their own pros and cons. The present study focused on the utilization of the shell of groundnut as lignocellulosic biomass material. The groundnut shell has no use after the collection of nuts from it. Preliminary characterization of groundnut shell was also conducted which showed it has 48.2% cellulose and hemicellulose; the lignin content was found to be 48.67%. The ash content of the biomass was around 3.13%. The lignin content of the biomass was considered as the target response for the pre-treatment process and butanol was used as an organic solvent for the pre-treatment process. The experimental study developed a quadratic model for the entire process with respect to the change in the lignin profile within the design criteria. The study also conducted raw and pre-treated biomass characterization using Fourier transform infrared spectroscopy. The study revealed that the maximum amount of lignin removed was 48.67% lignin.

Multifarious pretreatment strategies for the lignocellulosic substrates for the generation of renewable and sustainable biofuels: A review

Currently major part of the world’s energy requirements is fulfilled by fossil resources. Severe economic and environmental problems along with their limited resources are still a major issue. Long-term environmental and commercial concern has focussed into huge research in the past decades to replace fossil fuels with renewable sources of energy. The main focus of energy research is lignocellulosic substrates, which seems to be the best for energy application due to easily availability, cost-effective and environment favourable production process. Therefore, lignocellulosic materials provide economical, environmental and energetic benefits with an alternative to traditional or high cost substrates. However, the close association of major constituents of lignocellulosic biomass forms different barriers, which hinders the enzymatic hydrolysis of cellulose and hemicellulose to different fermentable sugars. To overcome this problem, different pretreatment approaches including physical, chemical, biological and combination of them have been used to improve the enzymatic accessibility or digestibility of lignocellulosic biomass. Various pretreatment methods have specific effect on different lignocellulosic components. Among all the methods, biological methods have performed better with respect to yield, cost and environmental related problems. Pretreated substrates from various pretreatments have been saccharified for the production of sustainable and renewable biofuels like ethanol, butanol, hydrogen, acetoin and 2,3-butanediol. • Multifarious pretreatment strategies for the lignocellulosic substrates. • Biological pretreatment of lignocellulosic biomass and analysis. • Production of renewable and sustainable biofuels from lignocellulosic substrates. • Techno-economical analysis of various pretreatment methods.

Efficient d-lactic acid production by Lactobacillus delbrueckii subsp. bulgaricus through conversion of organosolv pretreated lignocellulosic biomass

Lactic acid bioconversion processes have numerous advantages over the chemical synthesis route, not only due to the high-titer yield of the final product with great optical purity, but also due to the possibility of utilizing lignocellulosic biomass feedstocks as carbon source in an economic and environmentally friendly way. In the present study, beechwood and pine were pretreated with a novel mild oxidative organosolv process to produce cellulose-rich solid fractions, which were tested for their ability to support the growth and high lactic acid productivity of Lactobacillus delbrueckii subsp. bulgaricus (ATCC® 11842). We employed a simultaneous saccharification and fermentation (SSF) strategy in batch cultures with 9% w v−1 solids loading. The results for beechwood showed the highest production of 62 g L−1 lactic acid after 72 h of incubation, corresponding to a yield of 0.69 g g−1 of biomass (82.7% of the theoretical maximum yield) and a productivity of 0.86 g L−1 h−1. In the case of pine, the productivity was lower at 0.51 g L−1 h−1, leading to accumulation of 36.4 g L−1 lactic acid, corresponding to a yield of 0.40 g g−1 of biomass (41.4% of the theoretical maximum yield). Our study suggests that L. delbrueckii subsp. bulgaricus is an efficient lactic acid bacterial strain for the production of optically pure d-lactic acid from non-edible, organosolv pretreated hardwood and softwood biomass for the synthesis of bio-based plastics and other products.

A comparative study of artificial cow and sheep rumen fermentation of corn straw and food waste: Batch and continuous operation

To optimize the artificial rumen microorganism sources and develop a stable artificial rumen system, batch and continuous operation were investigated with corn straw and food waste as substrates. The batch trials evaluated the volatile fatty acid (VFA) yield, biogas production, and lignocellulose degradation efficiency. The continuous test evaluated the performance of the artificial cow and sheep rumen systems using a dynamic membrane bioreactor (DMBR) with a stepwise organic loading rate at mesophilic temperature. The anaerobic digestion (AD) of the lignocellulose biomass after rumen fermentation pretreatment and of the permeate from the artificial rumen system were also evaluated for CH4 production. The results indicated that the cow rumen microorganisms were more suitable than sheep rumen microorganisms for lignocellulosic biomass pretreatment and maximized the CH4 yield through the AD process without inhibition. After approximately four months of continuous operation, a stable and continuous artificial rumen system for lignocellulosic biomass degradation was achieved with cow rumen fluid as inoculum. Based on analysis of the core lignocellulose-degrading enzyme levels and gel filtration chromatography, the cow rumen microorganisms could secrete more extracellular multienzyme complexes to hydrolyze lignocellulosic biomass than the sheep rumen microorganisms in vitro. During the batch and continuous operations, a high diversity and similar richness of bacteria and fungi demonstrated that the cow rumen microorganisms can be used as a preferred inoculum for the artificial rumen system. The use of an artificial cow rumen system with a DMBR is a promising way to construct a stable and continuous artificial rumen system to biodegrade lignocellulosic biomass for biogas production.

Transformation of xylan into value-added biocommodities using Thermobacillus composti GH10 xylanase

Enzymatic transformation of xylans into renewable fuels and value-added products is mediated by xylanases. Here we describe the biochemical and X-ray structural characterization of Thermobacillus composti GH10 xylanase (TcXyn10A) at 2.1 Å resolution aiming to unravel details of its recognition of glucurono- and arabinoxylan at a molecular level. TcXyn10A improves the efficiency of pretreated lignocellulosic biomass hydrolysis by a commercial enzyme cocktail causing a 15.35 % increase in xylose release and 4.38 % glucose release after 24 h of reaction. The enzyme releases predominantly xylobiose and xylotriose, as well as MeGlcA3 × 3 (from beechwood glucuronoxylan) and a range of decorated xylooligosaccharides (XOS) from rye arabinoxylan, with Ara2 × 2 being the major product. The enzyme liberates XOS with the yields of 29.09 % for beechwood glucuronoxylan and 16.98 % for rye arabinoxylan. Finally, TcXyn10A has a high thermal stability, halotolerance, and resistance to ethanol, biochemical properties that can be desirable for a number of industrial applications.

Optimized screw profile design proved to inhibit re-agglomeration that occurs during extrusion of fine-milled forest residuals for producing fermentable sugars

The re-agglomeration phenomenon occurring during the extrusion process for pretreatment of lignocellulosic biomass under high temperature reduces the fermentable sugar yields. Prevention of the re-agglomeration at high-temperature extrusion is critical to enhancing the sugar yield. Lignocellulosic biomass was ground through a multi-step milling process and used as the raw material. The extrusion process was performed with different feedstock moisture contents of 50, 55, and 60 % (w.b.) and at barrel temperatures of 50, 100, 150, and 200 °C to create an environment that leads to re-agglomeration of the material after extrusion. A specific screw configuration was used to minimize the re-agglomeration and by modifying the heating and cooling zones. Water evaporation that induces the re-agglomeration during the extrusion process was inhibited with the new screw design without remarkable changes in the particle sizes. The particle sizes of D10, D50, and D90 were determined as 4.51–5.34 μm, 26.80–29.47 μm, and 102.33–110.67 μm, respectively.

Hydrothermal CO2-assisted Pretreatment of Wheat Straw for Hemicellulose Degradation Followed with Enzymatic Hydrolysis for Glucose Production

Hydrothermal CO2-assisted pretreatment was carried out for selective degradation of hemicellulose in wheat straw to produce pentose and enhancement the efficiency of enzymatic hydrolysis for glucose production. The FT-IR analysis and HPLC method was adopted to determine the observed chemical composition. Up to 90.0% of hemicelluloses were degraded under the optimum condition with temperature of 200 °C, CO2 pressure of 3 MPa and reaction time of 10 min, following with cellulose content in substrate increase from 37.6 to 58.1%. The efficiency of enzymatic hydrolysis was significantly improved after pretreatment, attributing to the loose structure of lignocelluloses after hemicellulose removal. More than 72.7% of glucose was achieved after enzymatic hydrolysis, by contrast, while the untreated sample was merely 30.2% due to enzymatic indigestibility. Additionally, SEM observations demonstrated that the densified structure of substrate was destructed, enhancing the accessibility and absorption of enzymes in the hydrolysis processing. The current results indicated that the hydrothermal CO2-assisted pretreatment was a feasible and effective approach for pretreatment of lignocellulosic biomass.

Evaluation Solvent Level Effect on Sugar Yield during Microwave-Assisted Pretreatment

An efficient pretreatment step is essential to ensure maximum and economical recovery of the fermentable sugar from enzymatic hydrolysis of lignocellulosic biomass. Microwave-assisted pretreatment was found to be a good alternative of conventional heating pretreatment of acid or alkali due to its direct heating of sample which reduce the energy consumption. The present study aims to evaluate the effect of using very diluted solvent (acid and alkali) on monomeric sugar yield during microwave-assisted pretreatment of lignocellulosic biomass (sago palm bark wastes). The changes of the surface structure of untreated and pretreated lignocellulosic biomass were detected using SEM analysis. Three solvents were employed at three concentrations (0.01, 0.05 and 0.1 N). The solvents that utilized in the microwave-assisted pretreatment were sulphuric acid (MA), sodium hydroxide (MH) and sodium bicarbonate (MB) and compared with distilled water (MW). Sago palm bark (SPB) was soaked in these solvents as a substrate at 5% w/v and subjected to microwave power at 800 W in a modified household microwave oven for 5 minutes. Immersing feedstock in distilled water and heating using microwave heating released 5.32 mg/g of monomeric sugar. Highest yield of monomeric sugar was found using 0.1N H2SO4 which yielded 10.28 mg/g during. Applying the pretreatment using the similar concentrations of NaOH and NaHCO3 released 9.35 and 4.31 mg/g of monomeric sugar, respectively. Decreasing chemical solvent level from 0.1 to 0.05 and 0.01 N shows a negative influence on sugar yield for MA and MH pretreatment while MB pretreatment displays a positive effect by extracting some useful components such as xylose.

Modeling of Pretreatment and Acid/Alkaline Hydrolyses of Lignocellulosic Biomasses in Twin-Screw Extruders

A mathematical model for pretreatment and hydrolysis of lignocellulosic biomasses in twin-screw extruders is presented. The model allows for calculation of the concentrations of extracted hemicellu...

Fungal pretreatment of lignocellulosic biomass for the production of plant hormone by Pichia fermentans under submerged conditions

The study was designed to evaluate the production of auxin by eukaryotic unicellular organism Pichia fermentans. Different media formulations were used for the production of indole-3-acetic acid (IAA) under broth and submerged conditions. Wheat straw-based production medium was formulated and optimized using statistical approach. The IAA production was significantly enhanced by nine folds, when the wheat straw was pretreated with Phanerochaete chrysosporium (150 µg/ml) as compared to untreated wheat straw (16.44 µg/ml). Partial purification of IAA was carried out by silica gel column chromatography and further confirmed by high-performance liquid chromatography. Exogenous application of crude and partially purified IAA positively influenced the Vigna radiata seedling growth. The number of lateral roots in the growing seedlings was significantly higher as compared to the control seeds. Thus, the present findings point towards an efficient production of plant hormone by yeast and white rot fungus using abundantly available wheat straw, which may lead to the development of cost-effective production of such metabolites and their further use in agricultural field to reduce the negative impact of chemical fertilizers.

Depolymerization of Lignin from Extracted Solid Waste of Cupressus lusitanica Mill. Biomass Using Imidazole

Implementation of green chemistry and biorefinery concept are needed to boost production of biomass-derived fuels, chemicals, and materials with cost-effective processing of sustainable feedstock. The use of imidazole as a novel solvent for biomass pretreatment creates an approach that helps accomplish this concept. The present work is dedicated to study the pretreatment of residual lignocellulosic biomass, namely, extracted solid waste of Cupressus lusitanica, by application of the alkaline solvent—imidazole. The pretreatment allowed obtaining cellulose- and hemicellulose-rich fractions, whereas lignin was depolymerized. Both cellulose and hemicellulose recovery were highly dependent on the reaction conditions. The highest cellulose content was obtained at 160 °C for 4 h and was 40.7 ± 0.6 wt% with a delignification yield of 65.2 ± 0.4 wt%. The effect of biomass delignification on the efficiency of enzymatic digestibility was also analyzed and it was observed a good linear relationship between the delignification yield and the glucan to glucose yield. The presence of added-value phenolic compounds from depolymerized lignin in recovered imidazole was analyzed by capillary electrophoresis and determination of total phenolic content and antioxidant activity was also performed. These compounds were tentatively identified and their structures proposed on the basis of the HPLC–MS analyzes.

Effect of bioactive compounds extracted from Cordyceps nidus ANDES-F1080 on laccase activity of Pleurotus ostreatus ANDES-F515

Laccases are ligninolytic enzymes produced by different microorganisms, especially by fungi such as the white-rot fungus Pleurotus ostreatus. Chemical inductors have been used to promote laccase secretion due to the application of these enzymes in lignocellulosic biomass pretreatment. Cordyceps nidus ANDES-F1080 was previously described as a source of bioactive compounds that could influence the enzymatic production system of other fungi. For that reason, this study evaluates the effect of C. nidus’ ANDES-F1080 extracts on the laccase activity of P. ostreatus ANDES-F515. To achieve this objective, C. nidus ANDES-F1080 was grown in four different substrates: two artificial-based and two natural-based culture media. Metabolites were extracted from C. nidus ANDES-F1080 using water and methanol as solvents. Biochemical characterization of these extracts was performed to complement the analysis of their effect on laccase activity. Our results revealed an enhancement on the laccase activity of P. ostreatus ANDES-F515 grown in natural-based cultures when C. nidus’ ANDES-F1080 extracts were supplemented. The best laccase activities registered values around 10,575 ± 813 U·L−1.

Subcritical CO2 shows no effect on liquid hot water pretreatment of poplar wood

Pretreatment of lignocellulosic biomass is required for many biorefinery processes. Previous studies have described hydrolysis of hemicelluloses by using liquid hot water (LHW) pretreatment. We evaluated the effect of carbonic acid originating from pressurized carbon dioxide during LHW pretreatment of poplar. The conditions applied covered temperatures from 120 to 200 °C, pretreatment times from 5 to 240 min and pressures from 1.0 to 2.2 MPa CO2 or N2. The pressure and the type of gas (CO2 or N2) did not have an effect on production of acetic acid, which functioned as a marker of progress of biomass hydrolysis. Results suggested that the presence of carbonic acid in the process does not significantly contribute to acidification. Deacetylation of lignocellulosic biomass can be achieved by LHW pretreatment irrespective of pressure and of gas type used, at the conditions tested.

Ionic liquid-tolerant cellulase system of Stachybotrys microspora exploited in the in situ saccharification of lignocellulosic biomass

Ionic liquids (ILs) are used as green solvents for pretreatment of lignocellulosic biomass before enzymatic hydrolysis for bioenergy production. The enzymatic saccharification of regenerated biomass must be carried in a two steps process (IL treatment followed by enzymatic one) because the majority of cellulase are inactive in the presence of ILs. In this study, a highly tolerant IL-cellulase system from the halophilic cellulolytic fungus Stachybotrys microspora is developed. The cellulase activity was enhanced to 115.5% and 114.5% in the presence of 5% (v/v) of 1-Ethyl-3-methylimidazolium diethyl phosphate [EMIM][DEP] and 1-Allyl-3-methylimidazolium chloride [AMIM][Cl] and retained 84.4% and 76.7% of activity in presence of 30% (v/v) of each compound, respectively. The cellulase was most sensitive to 1-Ethyl-3-methylimidazolium methyl sulphate [EMIM] [MtSO4] loosing 72% and 25% of initial activity after incubation in 5% and 30% solution of IL, respectively. The effectiveness of ILs for wheat bran pretreatment process shows the sequence: [EMIM][DEP] > [AMIM][Cl] > [EMIM] [MtSO4]. The IL-activated wheat bran slurry was enzymatically hydrolyzed in the best solvent [EMIM][DEP] diluted to 5, 10, 15 and 20% (v/v), the highest yield of reducing sugars, 52.4%, was obtained with the 15% pretreated substrate. Results showed a very high digestibility of the slurry and confirmed a high glucose yield for the pretreatment methodology. Indeed, the in situ saccharification of IL-pretreated wheat bran was significantly improved compared to the untreated (2.6 fold). Thus, a successful system in a one-pot procedure was developed.

Mechanical pretreatment of lignocellulosic biomass to improve biogas production: Comparison of results for giant reed and wheat straw

The effects of a mechanical pretreatment were determined on the methane yield of giant reed stems (Arundo Donax) and wheat straw. The feedstocks were pretreated using a two stages dry milling device, whose working capacity - up to 1,2 t h−1- can meet the requirements of medium and large-scale biogas plants. Untreated and pretreated materials were anaerobically digested in batch reactors under mesophilic conditions for 28 days. The cumulative biogas production from the pretreated giant reed stems exceeded 212 Nm3 t−1 of volatile solids, showing a 137% gain as compared to the raw material; furthermore, a significant decrease in the acid detergent fiber content was observed in the processed material. Pretreated straw reached a cumulative methane yield of 250.3 Nm3 t−1 of volatile solids, gaining a 49.1% as compared to the feedstock; no statistically significant differences were observed in physicochemical composition following pretreatment. The aforementioned gains resulted far above the known range for mechanical pretreatments. The specific electric energy requirement for pretreatment decreased from 76.5 kWh t−1 of processed giant reed stems to 66.0 kWh t−1 for straw. With reference to the use of biogas in CHP plants, the net electric energy output from pretreated materials was enhanced by about 111.7% and 38.3% as compared to the feedstocks for reed and straw, respectively. The cost for the extra electric energy produced by pretreatment was estimated at 0.034 and 0.048 € kWh−1 for giant reed and straw, respectively, resulting fully compatible with the selling price for the electric energy produced from biogas in force in Italy.

Correction to Pretreatment of Lignocellulosic Biomass Using Vortex-Based Devices for Cavitation: Influence on Biomethane Potential

ADVERTISEMENT RETURN TO ISSUEPREVAddition/CorrectionNEXTORIGINAL ARTICLEThis notice is a correctionCorrection to Pretreatment of Lignocellulosic Biomass Using Vortex-Based Devices for Cavitation: Influence on Biomethane PotentialSanjay NagarajanSanjay NagarajanMore by Sanjay Nagarajan and Vivek V. Ranade*Vivek V. Ranade*Email: [email protected]More by Vivek V. Ranadehttp://orcid.org/0000-0003-0558-6971Cite this: Ind. Eng. Chem. Res. 2020, 59, 19, 9340–9341Publication Date (Web):April 29, 2020Publication History Published online29 April 2020Published inissue 13 May 2020https://doi.org/10.1021/acs.iecr.0c01828Copyright © 2020 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views422Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (957 KB) Get e-Alerts Get e-Alerts

Interplay of Acid–Base Ratio and Recycling on the Pretreatment Performance of the Protic Ionic Liquid Monoethanolammonium Acetate

The use of protic ammonium ionic liquids (PILs) in the pretreatment of lignocellulosic biomass is a promising alternative to using expensive aprotic ionic liquids such as 1-ethyl-3-methylimidazoliu...

Production of bioethanol and xylitol from non-detoxified corn cob via a two-stage fermentation strategy

A novel two-stage fermentation strategy was applied to produce xylitol and ethanol from the whole acid-pretreated corn cob slurry. The acid-pretreated corn cob was used without filtration and detoxification by the two-stage fermentation with the robust Kluyveromyces marxianus CICC 1727-5. In the first stage, xylose in the slurry after dilute acid pretreatment of lignocellulosic biomass was used to produce xylitol under micro-aeration conditions. In the second stage, simultaneous saccharification fermentation was carried out, and the ethanol was produced from glucose releasing from the solid. Important parameters, such as aeration rate, cellulase loading during xylose utilization and SSF fermentation were studied for best performance. The two-stage fermentation strategy removed the inhibition of glucose on xylose, and little xylose was left in the fermentation broth. Under the optimized condition, the maximum ethanol and xylitol concentration were 52 g/L and 24.2 g/L corresponding to the yield of 0.41 g/g and 0.82 g/g, respectively.

Ammonia Fiber Expansion (AFEX) Pretreatment of Lignocellulosic Biomass.

Lignocellulosic materials are plant-derived feedstocks, such as crop residues (e.g., corn stover, rice straw, and sugar cane bagasse) and purpose-grown energy crops (e.g., miscanthus, and switchgrass) that are available in large quantities to produce biofuels, biochemicals, and animal feed. Plant polysaccharides (i.e., cellulose, hemicellulose, and pectin) embedded within cell walls are highly recalcitrant towards conversion into useful products. Ammonia fiber expansion (AFEX) is a thermochemical pretreatment that increases accessibility of polysaccharides to enzymes for hydrolysis into fermentable sugars. These released sugars can be converted into fuels and chemicals in a biorefinery. Here, we describe a laboratory-scale batch AFEX process to produce pretreated biomass on the gram-scale without any ammonia recycling. The laboratory-scale process can be used to identify optimal pretreatment conditions (e.g., ammonia loading, water loading, biomass loading, temperature, pressure, residence time, etc.) and generates sufficient quantities of pretreated samples for detailed physicochemical characterization and enzymatic/microbial analysis. The yield of fermentable sugars from enzymatic hydrolysis of corn stover pretreated using the laboratory-scale AFEX process is comparable to pilot-scale AFEX process under similar pretreatment conditions. This paper is intended to provide a detailed standard operating procedure for the safe and consistent operation of laboratory-scale reactors for performing AFEX pretreatment of lignocellulosic biomass.