The Experts below are selected from a list of 18783 Experts worldwide ranked by ideXlab platform
Helene Carrere - One of the best experts on this subject based on the ideXlab platform.
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Biological Pretreatments of biomass for improving biogas production: an overview from lab scale to full-scale
Renewable and Sustainable Energy Reviews, 2018Co-Authors: Ulysse Bremond, Jean-philippe Steyer, Raphaëlle De Buyer, Nicolas Bernet, Helene CarrereAbstract:Recent shifts in European countries biogas policies tend to limit the use of energy crops and encourage the use of manure, lignocellulosic feedstocks and bio-waste. The need to use feedstocks that are more difficult to handle (displaying either too low or too high biodegradation rates) is calling for the development of adapted Pretreatments. Among them, biological Pretreatments are very promising due to their reasonable cost, environmental friendliness and possible application to a wide spectrum of feedstocks. They can be divided into three categories: enzymatic, anaerobic and aerobic ones. This review aims at providing some guidelines on which type of biological pretreatment to apply for a given feedstock. To deliver such recommendations we considered the full range of technological readiness level. We gathered an analysis of the recent literature data obtained at lab or pilot scale focusing on methane yield enhancements and the description of some full-scale commercialized technologies. For lignocellulosic feedstocks, both enzymatic Pretreatments using lignin-modifying enzymes or carbohydrases and aerobic Pretreatments using consortia or simple aeration appear as promising. For bio-waste, anaerobic pretreatment via two-stage digestion seems to be an efficient biological pretreatment. For landfill, enzymatic treatment may be an interesting solution. Finally, for sludge digestion, both aerobic and anaerobic Pretreatments favouring autohydrolysis may be recommended. Full-scale applications already exist but their use remains scarce. Indeed, each biological pretreatment features technological issues. Enzymes have high production costs and limited activity in time. Anaerobic Pretreatments, notably two-stage digestion, are more expensive and complex to handle than a single stage. Finally, aerobic Pretreatments need fine tuning and control due to respiration mass loss. Research and development conducted toward these specific issues may allow these Pretreatments to become more cost-effective as well as practical and thus facilitate their development at full-scale.
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Improvement of anaerobic degradation by white-rot fungi pretreatment of lignocellulosic biomass: A review
Renewable and Sustainable Energy Reviews, 2016Co-Authors: E. Rouches, I. Herpoël-gimbert, Jean-philippe Steyer, Helene CarrereAbstract:Anaerobic digestion of lignocellulosic biomass appears to be an efficient process for the production of energy whilst answering present-day environmental challenges. However, lignin contained in lignocellulosic biomass is hardly biodegradable, thus representing a major obstacle for maximum methane production. Consequently, although Pretreatments need to be considered, their cost is a limit for their full-scale use. Biological Pretreatments are a cheaper alternative in this context. Several biological Pretreatments have been studied for anaerobic digestion: Ensiling, partial composting, specific microbial consortia, enzymes and fungi. Simple, inexpensive and efficient Pretreatments can be obtained using fungi. White-rot fungi (WRF), have been considered as most capable of delignifying a substrate. However, their use in the pretreatment of substrates for anaerobic digestion is quite recent and still needs to be investigated. This review compares fungal pretreatment with other biological treatments for anaerobic digestion of lignocellulosic biomass. Enzymatic mechanisms for WRF Pretreatments are then exposed. The literature data regarding the improvement of anaerobic digestibility with WRF pretreatment are summarized (anaerobic digestion and in vitro digestibility with rumen microorganisms). Finally, lignocellulosic biomass features allowing the improvement of anaerobic digestion are exposed (porosity, cellulose crystallinity, etc.). The possible effects of WRF on these characteristics are discussed and industrial perspectives for WRF Pretreatments are presented.
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review of feedstock pretreatment strategies for improved anaerobic digestion from lab scale research to full scale application
Bioresource Technology, 2016Co-Authors: Helene Carrere, Fabiana Passos, Georgia Antonopoulou, Rim Affes, Audrey Attimelli, G Lyberatos, Ive FerreAbstract:When properly designed, Pretreatments may enhance the methane potential and/or anaerobic digestion rate, improving digester performance. This paper aims at providing some guidelines on the most appropriate Pretreatments for the main feedstocks of biogas plants. Waste activated sludge was firstly investigated and implemented at full-scale, its thermal pretreatment with steam explosion being most recommended as it increases the methane potential and digestion rate, ensures sludge sanitation and the heat needed is produced on-site. Regarding fatty residues, saponification is preferred for enhancing their solubilisation and bioavailability. In the case of animal by-products, this pretreatment can be optimised to ensure sterilisation, solubilisation and to reduce inhibition linked to long chain fatty acids. With regards to lignocellulosic biomass, the first goal should be delignification, followed by hemicellulose and cellulose hydrolysis, alkali or biological (fungi) Pretreatments being most promising. As far as microalgae are concerned, thermal pretreatment seems the most promising technique so far.
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comparison of seven types of thermo chemical Pretreatments on the structural features and anaerobic digestion of sunflower stalks
Bioresource Technology, 2012Co-Authors: Florian Monlau, Jean-philippe Steyer, Abdellatif Barakat, Helene CarrereAbstract:Abstract Sunflower stalks can be used for the production of methane, but their recalcitrant structure requires the use of thermo-chemical Pretreatments. Two thermal (55 and 170 °C) and five thermo-chemical Pretreatments (NaOH, H 2 O 2 , Ca(OH) 2 , HCl and FeCl 3 ) were carried out, followed by anaerobic digestion. The highest methane production (259 ± 6 mL CH 4 g −1 VS) was achieved after pretreatment at 55 °C with 4% NaOH for 24 h. Acidic Pretreatments at 170 °C removed more than 90% of hemicelluloses and uronic acids whereas alkaline and oxidative Pretreatments were more effective in dissolving lignin. However, no pretreatment was effective in reducing the crystallinity of cellulose. Methane production rate was positively correlated with the amount of solubilized matter whereas methane potential was negatively correlated with the amount of lignin. Considering that the major challenge is obtaining increased methane potential, alkaline Pretreatments can be recommended in order to optimize the anaerobic digestion of lignocellulosic substrates.
Charles E. Wyman - One of the best experts on this subject based on the ideXlab platform.
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sugar yields from dilute oxalic acid pretreatment of maple wood compared to those with other dilute acids and hot water
Carbohydrate Polymers, 2013Co-Authors: Taiying Zhang, Rajeev Kumar, Charles E. WymanAbstract:Abstract Dilute oxalic acid pretreatment was applied to maple wood to improve compatibility with downstream operations, and its performance in pretreatment and subsequent enzymatic hydrolysis was compared to results for hydrothermal and dilute hydrochloric and sulfuric acid Pretreatments. The highest total xylose yield of ∼84% of the theoretical maximum was for both 0.5% oxalic and sulfuric acid pretreatment at 160 °C, compared to ∼81% yield for hydrothermal pretreatment at 200 °C and for 0.5% hydrochloric acid pretreatment at 140 °C. The xylooligomer fraction from dilute oxalic acid pretreatment was only 6.3% of the total xylose in solution, similar to results with dilute hydrochloric and sulfuric acids but much lower than the ∼70% value for hydrothermal pretreatment. Combining any of the four Pretreatments with enzymatic hydrolysis with 60 FPU cellulase/g of glucan plus xylan in the pretreated maple wood resulted in virtually the same total glucose plus xylose yields of ∼85% of the maximum possible.
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comparative data on effects of leading Pretreatments and enzyme loadings and formulations on sugar yields from different switchgrass sources
Bioresource Technology, 2011Co-Authors: Charles E. Wyman, Michael R Ladisch, Bruce E. Dale, Venkatesh Balan, Yoon Y Lee, Richard T Elander, Mark T Holtzapple, Matthew Falls, Bonnie Hames, Nathan S. MosierAbstract:Dilute sulfuric acid (DA), sulfur dioxide (SO2), liquid hot water (LHW), soaking in aqueous ammonia (SAA), ammonia fiber expansion (AFEX), and lime Pretreatments were applied to Alamo, Dacotah, and Shawnee switchgrass. Application of the same analytical methods and material balance approaches facilitated meaningful comparisons of glucose and xylose yields from combined pretreatment and enzymatic hydrolysis. Use of a common supply of cellulase, beta-glucosidase, and xylanase also eased comparisons. All Pretreatments enhanced sugar recovery from pretreatment and subsequent enzymatic hydrolysis substantially compared to untreated switchgrass. Adding beta-glucosidase was effective early in enzymatic hydrolysis while cellobiose levels were high but had limited effect on longer term yields at the enzyme loadings applied. Adding xylanase improved yields most for higher pH Pretreatments where more xylan was left in the solids. Harvest time had more impact on performance than switchgrass variety, and microscopy showed changes in different features could impact performance by different Pretreatments.
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physical and chemical characterizations of corn stover and poplar solids resulting from leading pretreatment technologies
Bioresource Technology, 2009Co-Authors: Rajeev Kumar, Venkatesh Balan, Gaurav Mago, Charles E. WymanAbstract:In order to investigate changes in substrate chemical and physical features after pretreatment, several characterizations were performed on untreated (UT) corn stover and poplar and their solids resulting Pretreatments by ammonia fiber expansion (AFEX), ammonia recycled percolation (ARP), controlled pH, dilute acid, flowthrough, lime, and SO(2) technologies. In addition to measuring the chemical compositions including acetyl content, physical attributes determined were biomass crystallinity, cellulose degree of polymerization, cellulase adsorption capacity of pretreated solids and enzymatically extracted lignin, copper number, FT-IR responses, scanning electron microscopy (SEM) visualizations, and surface atomic composition by electron spectroscopy of chemical analysis (ESCA). Lime pretreatment removed the most acetyl groups from both corn stover and poplar, while AFEX removed the least. Low pH Pretreatments depolymerized cellulose and enhanced biomass crystallinity much more than higher pH approaches. Lime pretreated corn stover solids and flowthrough pretreated poplar solids had the highest cellulase adsorption capacity, while dilute acid pretreated corn stover solids and controlled pH pretreated poplar solids had the least. Furthermore, enzymatically extracted AFEX lignin preparations for both corn stover and poplar had the lowest cellulase adsorption capacity. ESCA results showed that SO(2) pretreated solids had the highest surface O/C ratio for poplar, but for corn stover, the highest value was observed for dilute acid pretreatment with a Parr reactor. Although dependent on pretreatment and substrate, FT-IR data showed that along with changes in cross linking and chemical changes, Pretreatments may also decrystallize cellulose and change the ratio of crystalline cellulose polymorphs (Ialpha/Ibeta).
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Summary of findings from the Biomass Refining Consortium for Applied Fundamentals and Innovation (CAFI): corn stover pretreatment
Cellulose, 2009Co-Authors: Richard T Elander, Michael R Ladisch, Bruce E. Dale, Mark T Holtzapple, Y. Y. Lee, Colin Mitchinson, John N. Saddler, Charles E. WymanAbstract:The Biomass Refining Consortium for Applied Fundamentals and Innovation, with members from Auburn University, Dartmouth College, Michigan State University, the National Renewable Energy Laboratory, Purdue University, Texas A&M University, the University of British Columbia, and the University of California at Riverside, has developed comparative data on the conversion of corn stover to sugars by several leading pretreatment technologies. These technologies include ammonia fiber expansion pretreatment, ammonia recycle percolation pretreatment, dilute sulfuric acid pretreatment, flowthrough pretreatment (hot water or dilute acid), lime pretreatment, controlled pH hot water pretreatment, and sulfur dioxide steam explosion pretreatment. Over the course of two separate USDA- and DOE-funded projects, these pretreatment technologies were applied to two different corn stover batches, followed by enzymatic hydrolysis of the remaining solids from each pretreatment technology using identical enzyme preparations, enzyme loadings, and enzymatic hydrolysis assays. Identical analytical methods and a consistent material balance methodology were employed to develop comparative sugar yield data for each pretreatment and subsequent enzymatic hydrolysis. Although there were differences in the profiles of sugar release, with the more acidic Pretreatments releasing more xylose directly in the pretreatment step than the alkaline Pretreatments, the overall glucose and xylose yields (monomers + oligomers) from combined pretreatment and enzymatic hydrolysis process steps were very similar for all of these leading pretreatment technologies. Some of the water-only and alkaline pretreatment technologies resulted in significant amounts of residual xylose oligomers still remaining after enzymatic hydrolysis that may require specialized enzyme preparations to fully convert xylose oligomers to monomers.
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effects of cellulase and xylanase enzymes on the deconstruction of solids from pretreatment of poplar by leading technologies
Biotechnology Progress, 2009Co-Authors: Rajeev Kumar, Charles E. WymanAbstract:Comparative data is presented on glucose and xylose release for enzymatic hydrolysis of solids produced by pretreatment of poplar wood by ammonia fiber expansion (AFEX), ammonia recycled percolation (ARP), controlled pH, dilute acid, flowthrough (FT), lime, and sulfur dioxide (SO(2)) technologies. Sugar solubilization was measured for times of up to 72 h using cellulase supplemented with beta-glucosidase at an activity ratio of 1:2, respectively, at combined protein mass loadings of 5.8-116 mg/g of glucan in poplar wood prior to pretreatment. In addition, the enzyme cocktail was augmented with up to 11.0 g of xylanase protein per gram of cellulase protein at combined cellulase and beta-glucosidase mass loadings of 14.5 and 29.0 mg protein (about 7.5 and 15 FPU, respectively)/g of original potential glucose to evaluate cellulase-xylanase interactions. All pretreated poplar solids required high protein loadings to realize good sugar yields via enzymatic hydrolysis, and performance tended to be better for low pH Pretreatments by dilute sulfuric acid and sulfur dioxide, possibly due to higher xylose removal. Glucose release increased nearly linearly with residual xylose removal by enzymes for all Pretreatments, xylanase leverage on glucan removal decreased at high cellulase loadings. Washing the solids improved digestion for all Pretreatments and was particularly beneficial for controlled pH pretreatment. Furthermore, incubation of pretreated solids with BSA, Tween 20, or PEG6000 prior to adding enzymes enhanced yields, but the effectiveness of these additives varied with the type of pretreatment.
Bruce E. Dale - One of the best experts on this subject based on the ideXlab platform.
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comparative material balances around pretreatment technologies for the conversion of switchgrass to soluble sugars
Bioresource Technology, 2011Co-Authors: Rebecca J Garlock, Nathan S. Mosier, Bruce E. Dale, Venkatesh Balan, Ramesh V Pallapolu, Yoon Y Lee, Youngmi Kim, Michael R LadischAbstract:For this project, six chemical Pretreatments were compared for the Consortium for Applied Fundamentals and Innovation (CAFI): ammonia fiber expansion (AFEX), dilute sulfuric acid (DA), lime, liquid hot water (LHW), soaking in aqueous ammonia (SAA), and sulfur dioxide (SO2). For each pretreatment, a material balance was analyzed around the pretreatment, optional post-washing step, and enzymatic hydrolysis of Dacotah switchgrass. All Pretreatments + enzymatic hydrolysis solubilized over two-thirds of the available glucan and xylan. Lime, post-washed LHW, and SO2 achieved >83% total glucose yields. Lime, post-washed AFEX, and DA achieved >83% total xylose yields. Alkaline Pretreatments, except AFEX, solubilized the most lignin and a portion of the xylan as xylo-oligomers. As pretreatment pH decreased, total solubilized xylan and released monomeric xylose increased. Low temperature-long time or high temperature-short time Pretreatments are necessary for high glucose release from late-harvest Dacotah switchgrass but high temperatures may cause xylose degradation.
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comparative data on effects of leading Pretreatments and enzyme loadings and formulations on sugar yields from different switchgrass sources
Bioresource Technology, 2011Co-Authors: Charles E. Wyman, Michael R Ladisch, Bruce E. Dale, Venkatesh Balan, Yoon Y Lee, Richard T Elander, Mark T Holtzapple, Matthew Falls, Bonnie Hames, Nathan S. MosierAbstract:Dilute sulfuric acid (DA), sulfur dioxide (SO2), liquid hot water (LHW), soaking in aqueous ammonia (SAA), ammonia fiber expansion (AFEX), and lime Pretreatments were applied to Alamo, Dacotah, and Shawnee switchgrass. Application of the same analytical methods and material balance approaches facilitated meaningful comparisons of glucose and xylose yields from combined pretreatment and enzymatic hydrolysis. Use of a common supply of cellulase, beta-glucosidase, and xylanase also eased comparisons. All Pretreatments enhanced sugar recovery from pretreatment and subsequent enzymatic hydrolysis substantially compared to untreated switchgrass. Adding beta-glucosidase was effective early in enzymatic hydrolysis while cellobiose levels were high but had limited effect on longer term yields at the enzyme loadings applied. Adding xylanase improved yields most for higher pH Pretreatments where more xylan was left in the solids. Harvest time had more impact on performance than switchgrass variety, and microscopy showed changes in different features could impact performance by different Pretreatments.
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the impacts of pretreatment on the fermentability of pretreated lignocellulosic biomass a comparative evaluation between ammonia fiber expansion and dilute acid pretreatment
Biotechnology for Biofuels, 2009Co-Authors: Ming W Lau, Christa Gunawan, Bruce E. DaleAbstract:Background Pretreatment chemistry is of central importance due to its impacts on cellulosic biomass processing and biofuels conversion. Ammonia fiber expansion (AFEX) and dilute acid are two promising Pretreatments using alkaline and acidic pH that have distinctive differences in pretreatment chemistries.
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Summary of findings from the Biomass Refining Consortium for Applied Fundamentals and Innovation (CAFI): corn stover pretreatment
Cellulose, 2009Co-Authors: Richard T Elander, Michael R Ladisch, Bruce E. Dale, Mark T Holtzapple, Y. Y. Lee, Colin Mitchinson, John N. Saddler, Charles E. WymanAbstract:The Biomass Refining Consortium for Applied Fundamentals and Innovation, with members from Auburn University, Dartmouth College, Michigan State University, the National Renewable Energy Laboratory, Purdue University, Texas A&M University, the University of British Columbia, and the University of California at Riverside, has developed comparative data on the conversion of corn stover to sugars by several leading pretreatment technologies. These technologies include ammonia fiber expansion pretreatment, ammonia recycle percolation pretreatment, dilute sulfuric acid pretreatment, flowthrough pretreatment (hot water or dilute acid), lime pretreatment, controlled pH hot water pretreatment, and sulfur dioxide steam explosion pretreatment. Over the course of two separate USDA- and DOE-funded projects, these pretreatment technologies were applied to two different corn stover batches, followed by enzymatic hydrolysis of the remaining solids from each pretreatment technology using identical enzyme preparations, enzyme loadings, and enzymatic hydrolysis assays. Identical analytical methods and a consistent material balance methodology were employed to develop comparative sugar yield data for each pretreatment and subsequent enzymatic hydrolysis. Although there were differences in the profiles of sugar release, with the more acidic Pretreatments releasing more xylose directly in the pretreatment step than the alkaline Pretreatments, the overall glucose and xylose yields (monomers + oligomers) from combined pretreatment and enzymatic hydrolysis process steps were very similar for all of these leading pretreatment technologies. Some of the water-only and alkaline pretreatment technologies resulted in significant amounts of residual xylose oligomers still remaining after enzymatic hydrolysis that may require specialized enzyme preparations to fully convert xylose oligomers to monomers.
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comparative sugar recovery data from laboratory scale application of leading pretreatment technologies to corn stover
Bioresource Technology, 2005Co-Authors: Charles E. Wyman, Michael R Ladisch, Bruce E. Dale, Richard T Elander, Mark T Holtzapple, Yonghyun LeeAbstract:Biological processing of cellulosic biomass to fuels and chemicals would open up major new agricultural markets and provide powerful societal benefits, but pretreatment operations essential to economically viable yields have a major impact on costs and performance of the entire system. However, little comparative data is available on promising Pretreatments. To aid in selecting appropriate systems, leading Pretreatments based on ammonia explosion, aqueous ammonia recycle, controlled pH, dilute acid, flowthrough, and lime were evaluated in a coordinated laboratory program using a single source of corn stover, the same cellulase enzyme, shared analytical methods, and common data interpretation approaches to make meaningful comparisons possible for the first time. Each pretreatment made it possible to subsequently achieve high yields of glucose from cellulose by cellulase enzymes, and the cellulase formulations used were effective in solubilizing residual xylan left in the solids after each pretreatment. Thus, overall sugar yields from hemicellulose and cellulose in the coupled pretreatment and enzymatic hydrolysis operations were high for all of the Pretreatments with corn stover. In addition, high-pH methods were found to offer promise in reducing cellulase use provided hemicellulase activity can be enhanced. However, the substantial differences in sugar release patterns in the pretreatment and enzymatic hydrolysis operations have important implications for the choice of process, enzymes, and fermentative organisms.
Michael R Ladisch - One of the best experts on this subject based on the ideXlab platform.
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Severity factor coefficients for subcritical liquid hot water pretreatment of hardwood chips.
Biotechnology and Bioengineering, 2013Co-Authors: Thomas Kreke, Nathan S. Mosier, Michael R LadischAbstract:: Single stage and multi-stage liquid hot water Pretreatments of mixed hardwood pinchips were investigated at various severities (log R0 = 3.65-4.81) to assess the efficiencies of the Pretreatments with respect to achieving high pentose sugar yields and improved enzymatic digestibility of pretreated cellulose. We investigate the effect of pretreatment parameters that is, temperature, and time, as expressed in the severity factor, on the recovery of sugars and hydrolyzability of pretreated cellulose. We find the severity factor, in its widely used form, is an incomplete measure for evaluating the pretreatment efficiencies and predicting overall sugar yields when pretreatment temperatures above 200°C are used. Corrections to the severity factor and its correlation to the measured pretreatment responses (% xylan solubilization, xylan recovery as fermentable sugars, cellulose enzymatic digestibility) indicate a greater influence of temperature on the pretreatment efficiencies than predicted by the commonly used severity factor. A low temperature, long residence time is preferred for hemicellulose dissolution during the pretreatment since the condition favors oligosaccharide and monomeric sugar formation over sugar degradation. On the contrary, high cellulose hydrolyzability is achieved with a high temperature (>200°C), high severity pretreatment when pretreatment is followed by enzyme hydrolysis. In multi-stage pretreatment, the first low-severity pretreatment is optimized for solubilizing fast-hydrolyzing hemicellulose while minimizing formation of furans. The subsequent pretreatment is carried out at over 200°C to recover the difficult-to-hydrolyze hemicellulose fraction as well as to increase susceptibility of pretreated cellulose to enzymes. High recovery (>92%) of hemicellulose-derived pentose sugars and enhanced enzymatic hydrolysis of pretreated cellulose (where >80% glucose yield results with 20 FPU = 32 mg protein/g glucan or 10-13 mg/g initial hardwood) are achieved by applying a multi-stage pretreatment. This work shows how the severity equation may be used to obtain a single characteristic curve that correlate xylan solubilization and enzymatic cellulose hydrolysis as a function of severity at pretreatment temperatures up to 230°C.
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comparative material balances around pretreatment technologies for the conversion of switchgrass to soluble sugars
Bioresource Technology, 2011Co-Authors: Rebecca J Garlock, Nathan S. Mosier, Bruce E. Dale, Venkatesh Balan, Ramesh V Pallapolu, Yoon Y Lee, Youngmi Kim, Michael R LadischAbstract:For this project, six chemical Pretreatments were compared for the Consortium for Applied Fundamentals and Innovation (CAFI): ammonia fiber expansion (AFEX), dilute sulfuric acid (DA), lime, liquid hot water (LHW), soaking in aqueous ammonia (SAA), and sulfur dioxide (SO2). For each pretreatment, a material balance was analyzed around the pretreatment, optional post-washing step, and enzymatic hydrolysis of Dacotah switchgrass. All Pretreatments + enzymatic hydrolysis solubilized over two-thirds of the available glucan and xylan. Lime, post-washed LHW, and SO2 achieved >83% total glucose yields. Lime, post-washed AFEX, and DA achieved >83% total xylose yields. Alkaline Pretreatments, except AFEX, solubilized the most lignin and a portion of the xylan as xylo-oligomers. As pretreatment pH decreased, total solubilized xylan and released monomeric xylose increased. Low temperature-long time or high temperature-short time Pretreatments are necessary for high glucose release from late-harvest Dacotah switchgrass but high temperatures may cause xylose degradation.
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comparative data on effects of leading Pretreatments and enzyme loadings and formulations on sugar yields from different switchgrass sources
Bioresource Technology, 2011Co-Authors: Charles E. Wyman, Michael R Ladisch, Bruce E. Dale, Venkatesh Balan, Yoon Y Lee, Richard T Elander, Mark T Holtzapple, Matthew Falls, Bonnie Hames, Nathan S. MosierAbstract:Dilute sulfuric acid (DA), sulfur dioxide (SO2), liquid hot water (LHW), soaking in aqueous ammonia (SAA), ammonia fiber expansion (AFEX), and lime Pretreatments were applied to Alamo, Dacotah, and Shawnee switchgrass. Application of the same analytical methods and material balance approaches facilitated meaningful comparisons of glucose and xylose yields from combined pretreatment and enzymatic hydrolysis. Use of a common supply of cellulase, beta-glucosidase, and xylanase also eased comparisons. All Pretreatments enhanced sugar recovery from pretreatment and subsequent enzymatic hydrolysis substantially compared to untreated switchgrass. Adding beta-glucosidase was effective early in enzymatic hydrolysis while cellobiose levels were high but had limited effect on longer term yields at the enzyme loadings applied. Adding xylanase improved yields most for higher pH Pretreatments where more xylan was left in the solids. Harvest time had more impact on performance than switchgrass variety, and microscopy showed changes in different features could impact performance by different Pretreatments.
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Summary of findings from the Biomass Refining Consortium for Applied Fundamentals and Innovation (CAFI): corn stover pretreatment
Cellulose, 2009Co-Authors: Richard T Elander, Michael R Ladisch, Bruce E. Dale, Mark T Holtzapple, Y. Y. Lee, Colin Mitchinson, John N. Saddler, Charles E. WymanAbstract:The Biomass Refining Consortium for Applied Fundamentals and Innovation, with members from Auburn University, Dartmouth College, Michigan State University, the National Renewable Energy Laboratory, Purdue University, Texas A&M University, the University of British Columbia, and the University of California at Riverside, has developed comparative data on the conversion of corn stover to sugars by several leading pretreatment technologies. These technologies include ammonia fiber expansion pretreatment, ammonia recycle percolation pretreatment, dilute sulfuric acid pretreatment, flowthrough pretreatment (hot water or dilute acid), lime pretreatment, controlled pH hot water pretreatment, and sulfur dioxide steam explosion pretreatment. Over the course of two separate USDA- and DOE-funded projects, these pretreatment technologies were applied to two different corn stover batches, followed by enzymatic hydrolysis of the remaining solids from each pretreatment technology using identical enzyme preparations, enzyme loadings, and enzymatic hydrolysis assays. Identical analytical methods and a consistent material balance methodology were employed to develop comparative sugar yield data for each pretreatment and subsequent enzymatic hydrolysis. Although there were differences in the profiles of sugar release, with the more acidic Pretreatments releasing more xylose directly in the pretreatment step than the alkaline Pretreatments, the overall glucose and xylose yields (monomers + oligomers) from combined pretreatment and enzymatic hydrolysis process steps were very similar for all of these leading pretreatment technologies. Some of the water-only and alkaline pretreatment technologies resulted in significant amounts of residual xylose oligomers still remaining after enzymatic hydrolysis that may require specialized enzyme preparations to fully convert xylose oligomers to monomers.
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comparative sugar recovery data from laboratory scale application of leading pretreatment technologies to corn stover
Bioresource Technology, 2005Co-Authors: Charles E. Wyman, Michael R Ladisch, Bruce E. Dale, Richard T Elander, Mark T Holtzapple, Yonghyun LeeAbstract:Biological processing of cellulosic biomass to fuels and chemicals would open up major new agricultural markets and provide powerful societal benefits, but pretreatment operations essential to economically viable yields have a major impact on costs and performance of the entire system. However, little comparative data is available on promising Pretreatments. To aid in selecting appropriate systems, leading Pretreatments based on ammonia explosion, aqueous ammonia recycle, controlled pH, dilute acid, flowthrough, and lime were evaluated in a coordinated laboratory program using a single source of corn stover, the same cellulase enzyme, shared analytical methods, and common data interpretation approaches to make meaningful comparisons possible for the first time. Each pretreatment made it possible to subsequently achieve high yields of glucose from cellulose by cellulase enzymes, and the cellulase formulations used were effective in solubilizing residual xylan left in the solids after each pretreatment. Thus, overall sugar yields from hemicellulose and cellulose in the coupled pretreatment and enzymatic hydrolysis operations were high for all of the Pretreatments with corn stover. In addition, high-pH methods were found to offer promise in reducing cellulase use provided hemicellulase activity can be enhanced. However, the substantial differences in sugar release patterns in the pretreatment and enzymatic hydrolysis operations have important implications for the choice of process, enzymes, and fermentative organisms.
Jean-philippe Steyer - One of the best experts on this subject based on the ideXlab platform.
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Biological Pretreatments of biomass for improving biogas production: an overview from lab scale to full-scale
Renewable and Sustainable Energy Reviews, 2018Co-Authors: Ulysse Bremond, Jean-philippe Steyer, Raphaëlle De Buyer, Nicolas Bernet, Helene CarrereAbstract:Recent shifts in European countries biogas policies tend to limit the use of energy crops and encourage the use of manure, lignocellulosic feedstocks and bio-waste. The need to use feedstocks that are more difficult to handle (displaying either too low or too high biodegradation rates) is calling for the development of adapted Pretreatments. Among them, biological Pretreatments are very promising due to their reasonable cost, environmental friendliness and possible application to a wide spectrum of feedstocks. They can be divided into three categories: enzymatic, anaerobic and aerobic ones. This review aims at providing some guidelines on which type of biological pretreatment to apply for a given feedstock. To deliver such recommendations we considered the full range of technological readiness level. We gathered an analysis of the recent literature data obtained at lab or pilot scale focusing on methane yield enhancements and the description of some full-scale commercialized technologies. For lignocellulosic feedstocks, both enzymatic Pretreatments using lignin-modifying enzymes or carbohydrases and aerobic Pretreatments using consortia or simple aeration appear as promising. For bio-waste, anaerobic pretreatment via two-stage digestion seems to be an efficient biological pretreatment. For landfill, enzymatic treatment may be an interesting solution. Finally, for sludge digestion, both aerobic and anaerobic Pretreatments favouring autohydrolysis may be recommended. Full-scale applications already exist but their use remains scarce. Indeed, each biological pretreatment features technological issues. Enzymes have high production costs and limited activity in time. Anaerobic Pretreatments, notably two-stage digestion, are more expensive and complex to handle than a single stage. Finally, aerobic Pretreatments need fine tuning and control due to respiration mass loss. Research and development conducted toward these specific issues may allow these Pretreatments to become more cost-effective as well as practical and thus facilitate their development at full-scale.
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Improvement of anaerobic degradation by white-rot fungi pretreatment of lignocellulosic biomass: A review
Renewable and Sustainable Energy Reviews, 2016Co-Authors: E. Rouches, I. Herpoël-gimbert, Jean-philippe Steyer, Helene CarrereAbstract:Anaerobic digestion of lignocellulosic biomass appears to be an efficient process for the production of energy whilst answering present-day environmental challenges. However, lignin contained in lignocellulosic biomass is hardly biodegradable, thus representing a major obstacle for maximum methane production. Consequently, although Pretreatments need to be considered, their cost is a limit for their full-scale use. Biological Pretreatments are a cheaper alternative in this context. Several biological Pretreatments have been studied for anaerobic digestion: Ensiling, partial composting, specific microbial consortia, enzymes and fungi. Simple, inexpensive and efficient Pretreatments can be obtained using fungi. White-rot fungi (WRF), have been considered as most capable of delignifying a substrate. However, their use in the pretreatment of substrates for anaerobic digestion is quite recent and still needs to be investigated. This review compares fungal pretreatment with other biological treatments for anaerobic digestion of lignocellulosic biomass. Enzymatic mechanisms for WRF Pretreatments are then exposed. The literature data regarding the improvement of anaerobic digestibility with WRF pretreatment are summarized (anaerobic digestion and in vitro digestibility with rumen microorganisms). Finally, lignocellulosic biomass features allowing the improvement of anaerobic digestion are exposed (porosity, cellulose crystallinity, etc.). The possible effects of WRF on these characteristics are discussed and industrial perspectives for WRF Pretreatments are presented.
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comparison of seven types of thermo chemical Pretreatments on the structural features and anaerobic digestion of sunflower stalks
Bioresource Technology, 2012Co-Authors: Florian Monlau, Jean-philippe Steyer, Abdellatif Barakat, Helene CarrereAbstract:Abstract Sunflower stalks can be used for the production of methane, but their recalcitrant structure requires the use of thermo-chemical Pretreatments. Two thermal (55 and 170 °C) and five thermo-chemical Pretreatments (NaOH, H 2 O 2 , Ca(OH) 2 , HCl and FeCl 3 ) were carried out, followed by anaerobic digestion. The highest methane production (259 ± 6 mL CH 4 g −1 VS) was achieved after pretreatment at 55 °C with 4% NaOH for 24 h. Acidic Pretreatments at 170 °C removed more than 90% of hemicelluloses and uronic acids whereas alkaline and oxidative Pretreatments were more effective in dissolving lignin. However, no pretreatment was effective in reducing the crystallinity of cellulose. Methane production rate was positively correlated with the amount of solubilized matter whereas methane potential was negatively correlated with the amount of lignin. Considering that the major challenge is obtaining increased methane potential, alkaline Pretreatments can be recommended in order to optimize the anaerobic digestion of lignocellulosic substrates.