共查询到20条相似文献,搜索用时 316 毫秒
1.
Amit Kumar Jay B. Cameron Peter C. Flynn 《Applied biochemistry and biotechnology》2005,121(1-3):47-58
Issues of traffic congestion and community acceptance limit the size of biomass-processing plants based on truck delivery
to about 2 million (M) dry t/yr or less. In this study, the cost of ethanol from an ethanol fermentation plant processing
2 M dry t/yr of corn stover supplied by truck is compared with that of larger plants in the range of 4–38 M dry t/yr supplied
by a combination of trucks plus pipelines. For corn stover, a biomass source with a low yield per gross hectare, the cost
of ethanol from larger plants is always higher. For wood chips from the boreal forest, a biomass source with a relatively
high yield per gross hectare, a plant processing 14–38 M dry t/yr produces ethanol at a 13% reduction in cost compared with
a plant producing 2 M dry t/yr supplied by truck. Processing of value-added products, such as chemicals from lignin, would
be enabled by larger-scale plants. 相似文献
2.
Optimization of steam pretreatment of corn stover to enhance enzymatic digestibility 总被引:5,自引:0,他引:5
Among the available agricultural byproducts, corn stover, with its yearly production of 10 million t (dry basis), is the most
abundant promising raw material for fuel ethanol production in Hungary. In the United States, more than 216 million to fcorn
stover is produced annually, of which a portion also could possibly be collected for conversion to ethanol. However, a network
of lignin and hemicellulose protects cellulose, which is the major source of fermentable sugars in corn stover (approx 40%
of the dry matter [DM]). Steam pretreatment removes the major part of the hemicellulose from the solid material and makes
the cellulose more susceptible to enzymatic digestion. We studied 12 different combinations of reaction temperature, time,
and pH during steam pretreatment. The best conditions (200°C, 5 min, 2% H2SO4) increased the enzymatic conversion (from cellulose to glucose) of corn stover more then four times, compared to untreated
material. However, steam pretreatment at 190°C for 5 min with 2% sulfuric acid resulted in the highest overall yield of sugars,
56.1 g from 100 g of untreated material (DM), corresponding to 73% of the theoretical. The liquor following steam explosion
was fermented using Saccharomyces cerevisiae to investigate the inhibitory effect of the pretreatment. The achieved ethanol yield was slightly higher than that obtained
with a reference sugar solution. This demonstrates that baker's yeast could adapt to the pretreated liquor and ferment the
glucose to ethanol efficiently. 相似文献
3.
Richard G. Nelson Marie Walsh John J. Sheehan Robin Graham 《Applied biochemistry and biotechnology》2004,113(1-3):13-26
A methodology was developed to estimate quantities of crop residues that can be removed while maintaining rain or wind erosion
at less than or equal to the tolerable soil-loss level. Six corn and wheat rotations in the 10 largest corn-producing states
were analyzed. Residue removal rates for each rotation were evaluated for conventional, mulch/reduced, and no-till field operations.
The analyses indicated that potential removable maximum quantities range from nearly 5.5 million dry metric t/yr for a continuous
corn rotation using conventional till in Kansas to more than 97 million dry metric t/yr for a corn-wheat rotation using no-till
in Illinois. 相似文献
4.
Effects of temperature and moisture on dilute-acid steam explosion pretreatment of corn stover and cellulase enzyme digestibility 总被引:3,自引:0,他引:3
Melvin P. Tucker Kyoung H. Kim Mildred M. Newman Quang A. Nguyen 《Applied biochemistry and biotechnology》2003,105(1-3):165-177
Corn stover is emerging as a viable feedstock for producing bioethanol from renewable resources. Dilute-acid pretreatment
of corn stover can solubilize a significant portion of the hemicellulosic component and enhance the enzymatic digestibility
of the remaining cellulose for fermentation into ethanol. In this study, dilute H2SO4 pretreatment of corn stover was performed in a steam explosion reactor at 160°C, 180°C, and 190°C, approx 1 wt% H2SO4, and 70-s to 840-s residence times. The combined severity (Log10 [R
o
] - pH), an expression relating pH, temperature, and residence time of pretreatment, ranged from 1.8 to 2.4. Soluble xylose
yields varied from 63 to 77% of theoretical from pretreatments of corn stover at 160 and 180°C. However, yields >90% of theoretical
were found with dilute-acid pretreatments at 190°C. A narrower range of higher combined severities was required for pretreatment
to obtain high soluble xylose yields when the moisture content of the acid-impregnated feedstock was increased from 55 to
63 wt%. Simultaneous saccharification and fermentation (SSF) of washed solids from corn stover pretreated at 190°C, using
an enzyme loading of 15 filter paper units (FPU)/g of cellulose, gave ethanol yields in excess of 85%. Similar SSF ethanol
yields were found using washed solid residues from 160 and 180°C pretreatments at similar combined severities but required
a higher enzyme loading of approx 25 FPU/g of cellulose. 相似文献
5.
J. Richard Hess Kevin L. Kenney Christopher T. Wright Robert Perlack Anthony Turhollow 《Cellulose (London, England)》2009,16(4):599-619
As biorefining conversion technologies become commercial, feedstock availability, supply system logistics, and biomass material
attributes are emerging as major barriers to the availability of corn stover for biorefining. While systems do exist to supply
corn stover as feedstock to biorefining facilities, stover material attributes affecting physical deconstruction, such as
densification and post-harvest material stability, challenge the cost-effectiveness of present-day feedstock logistics systems.
In addition, the material characteristics of corn stover create barriers with any supply system design in terms of equipment
capacity/efficiency, dry matter loss, and capital use efficiency. However, analysis of a conventional large square bale corn
stover feedstock supply system concludes that (1) where other agronomic factors are not limiting, corn stover can be accessed
and supplied to a biorefinery using existing bale-based technologies, (2) technologies and new supply system designs are necessary
to overcome biomass bulk density and moisture material property challenges, and (3) major opportunities to improve conventional
bale biomass feedstock supply systems include improvements in equipment efficiency and capacity and reducing biomass losses
in harvesting, collection, and storage. Finally, the backbone of an effective stover supply system design is the optimization
of intended and minimization of unintended material property changes as the corn stover passes through the individual supply
system processes from the field to the biorefinery conversion processes.
相似文献
J. Richard HessEmail: |
6.
William A. Smith David N. Thompson Vicki S. Thompson Corey W. Radtke Brady Carter 《Applied biochemistry and biotechnology》2009,154(1-3):108-122
Enzymatic preprocessing of lignocellulosic biomass in dry storage systems has the potential to improve feedstock characteristics and lower ethanol production costs. To assess the potential for endoxylanase activity at low water contents, endoxylanase activity was tested using a refined wheat arabinoxylan substrate and three commercial endoxylanases over the water activity range 0.21–1.0, corresponding to water contents of 5% to >60% (dry basis). Homogeneously mixed dry samples were prepared at a fixed enzyme to substrate ratio and incubated in chambers at a variety of fixed water activities. Replicates were sacrificed periodically, and endoxylanase activity was quantified as an increase in reducing sugar relative to desiccant-stored controls. Endoxylanase activity was observed at water activities over 0.91 in all enzyme preparations in less than 4 days and at a water activity of 0.59 in less than 1 week in two preparations. Endoxylanase activity after storage was confirmed for selected desiccant-stored controls by incubation at 100% relative humidity. Water content to water activity relationships were determined for three lignocellulosic substrates, and results indicate that two endoxylanase preparations retained limited activity as low as 7% to 13% water content (dry basis), which is well within the range of water contents representative of dry biomass storage. Future work will examine the effects of endoxylanase activity toward substrates such as corn stover, wheat straw, and switchgrass in low water content environments. 相似文献
7.
David W. Templeton Amie D. Sluiter Tammy K. Hayward Bonnie R. Hames Steven R. Thomas 《Cellulose (London, England)》2009,16(4):621-639
Corn stover, the above-ground, non-grain portion of the crop, is a large, currently available source of biomass that potentially
could be collected as a biofuels feedstock. Biomass conversion process economics are directly affected by the overall biochemical
conversion yield, which is assumed to be proportional to the carbohydrate content of the feedstock materials used in the process.
Variability in the feedstock carbohydrate levels affects the maximum theoretical biofuels yield and may influence the optimum
pretreatment or saccharification conditions. The aim of this study is to assess the extent to which commercial hybrid corn
stover composition varies and begin to partition the variation among genetic, environmental, or annual influences. A rapid
compositional analysis method using near-infrared spectroscopy/partial least squares multivariate modeling (NIR/PLS) was used
to evaluate compositional variation among 508 commercial hybrid corn stover samples collected from 47 sites in eight Corn
Belt states after the 2001, 2002, and 2003 harvests. The major components of the corn stover, reported as average (standard
deviation) % dry weight, whole biomass basis, were glucan 31.9 (2.0), xylan 18.9 (1.3), solubles composite 17.9 (4.1), and
lignin (corrected for protein) 13.3 (1.1). We observed wide variability in the major corn stover components. Much of the variation
observed in the structural components (on a whole biomass basis) is due to the large variation found in the soluble components.
Analysis of variance (ANOVA) showed that the harvest year had the strongest effect on corn stover compositional variation,
followed by location and then variety. The NIR/PLS rapid analysis method used here is well suited to testing large numbers
of samples, as tested in this study, and will support feedstock improvement and biofuels process research. 相似文献
8.
Ethanol production from steam-explosion pretreated wheat straw 总被引:1,自引:0,他引:1
Ignacio Ballesteros Ma José Negro José Miguel Oliva Araceli Cabañas Paloma Manzanares Mercedes Ballesteros 《Applied biochemistry and biotechnology》2006,130(1-3):496-508
Bioconversion of cereal straw to bioethanol is becoming an attractive alternative to conventional fuel ethanol production
from grains. In this work, the best operational conditions for steam-explosion pretreatment of wheat straw for ethanol production
by a simultaneous saccharification and fermentation process were studied, using diluted acid [H2SO4 0.9% (w/w)] and water as preimpregnation agents. Acid-or water-impregnated biomass was steam-exploded at different temperatures
(160–200°C) and residence times (5, 10, and 20 min). Composition of solid and filtrate obtained after pretreatment, enzymatic
digestibility and ethanol production of pretreated wheat straw at different experimental conditions was analyzed. The best
pretreatment conditions to obtain high conversion yield to ethanol (approx 80% of theoretical) of cellulose-rich residue after
steam-explosion were 190°C and 10 min or 200°C and 5 min, in acid-impregnated straw. However, 180°C for 10 min in acid-impregnated
biomass provided the highest ethanol yield referred to raw material (140 L/t wheat straw), and sugars recovery yield in the
filtrate (300 g/kg wheat straw). 相似文献
9.
Production of 5-Hydroxymethylfurfural and Furfural from Lignocellulosic Biomass in Water-Tetrahydrofuran Media with Sodium Bisulfate 下载免费PDF全文
5-Hydroxymethylfurfural (HMF) and furfural (FF), two bio-based platform chemicals, were produced from various raw lignocellulosic materials (corncob, corn stover, wheat straw, rice straw and sugarcane bagasse) in a water-tetrahydrofuran media by using NaHSO4 as catalyst. The in fluences of reaction temperature (160-200 oC), reaction time (30-120 min), solvent volume ratio, feedstock concentration (2.4wt%-11.1wt%) and catalyst dosage were studied. The highest HMF and FF yields obtained from corncob were 47mol% and 56mol% under condition of 190 oC, 90 min, 10/1 of THF/H2O. Besides, the lignin in the raw biomass wasalso depolymerized into organosolv lignin. 相似文献
10.
Mette Hedegaard Thomsen Anders Thygesen Henning Jørgensen Jan Larsen Børge Holm Christensen Anne Belinda Thomsen 《Applied biochemistry and biotechnology》2006,130(1-3):448-460
The overall objective in this European Union-project is to develop cost and energy effective production systems for coproduction
of bioethanol and electricity based on integrated biomass utilization. A pilot plan reactor for hydrothermal pretreatment
(including weak acid hydrolysis, wet oxidation, and steam pretreatment) with a capacity of 100 kg/h was constructed and tested
for pretreatment of wheat straw for ethanol production. Highest hemicellulose (C5 sugar) recovery and extraction of hemicellulose
sugars was obtained at 190°C whereas highest C6 sugar yield was obtained at 200°C. Lowest toxicity of hydrolysates was observed
at 190°C; however, addition of H2O2 improved the fermentability and sugar recoveries at the higher temperatures. The estimated total ethanol production was 223
kg/t straw assuming utilisation of both C6 and C5 during fermentation, and 0.5 g ethanol/g sugar. 相似文献
11.
Measurement of rheological properties of corn stover suspensions 总被引:1,自引:0,他引:1
Corn stover is currently being evaluated as a feedstock for ethanol production. The corn stover suspensions fed to reactors
typically range between 10 and 40% solids. To simulate and design bioreactors for processing highly loaded corn stover suspensions,
the rheologic properties of the suspension must be measured. In systems with suspended solids, rheologic measurements are
difficult to perform owing to settling in the measurement devices. In this study, viscosities of corn stover suspensions were
measured using a helical ribbon impeller viscometer. A calibration procedure is required for the impeller method in order
to obtain the shear rate constant, k, which is dependent on the geometry of the measurement system. The corn stover suspensions are described using a power law
flow model. 相似文献
12.
Ammonia fiber explosion treatment of corn stover 总被引:1,自引:0,他引:1
Farzaneh Teymouri Lizbeth Laureano-Pérez Hasan Alizadeh Bruce E. Dale 《Applied biochemistry and biotechnology》2004,115(1-3):951-963
Optimizing process conditions and parameters such as ammonia loading, moisture content of biomass, temperature, and residence
time is necessary for maximum effectiveness of the ammonia fiber explosion process. Approximate optimal pretreatment conditions
for corn stover were found to be temperature of 90°C, ammonia: dry corn stover mass ratio of 1∶1, moisture content of corn
stover of 60% (dry weight basis), and residence time (holding at target temperature), of 5 min. Approximately 98% of the theoretical
glucose yield was obtained during enzymatic hydrolysis of the optimal treated corn stover using 60 filter paper units (FPU)
of cellulase enzyme/g of glucan (equal to 22 FPU/g of dry corn stover). The ethanol yield from this sample was increased up
to 2.2 times over that of untreated sample. Lowering enzyme loading to 15 and 7.5 FPU/g of glucan did not significantly affect
the glucose yield compared with 60 FPU, and any differences between effects at different enzyme levels decreased as the treatment
temperature increased. 相似文献
13.
Fermentation of Biologically Pretreated Wheat Straw for Ethanol Production: Comparison of Fermentative Microorganisms and Process Configurations 总被引:2,自引:0,他引:2
María López-Abelairas Thelmo Alejandro Lu-Chau Juan Manuel Lema 《Applied biochemistry and biotechnology》2013,170(8):1838-1852
The pretreatment of lignocellulosic biomass with white-rot fungi to produce bioethanol is an environmentally friendly alternative to the commonly used physico-chemical processes. After biological pretreatment, a solid substrate composed of cellulose, hemicellulose and lignin, the two latter with a composition lower than that of the initial substrate, is obtained. In this study, six microorganisms and four process configurations were utilised to ferment a hydrolysate obtained from wheat straw pretreated with the white-rot fungus Irpex lacteus. To enhance total sugars utilisation, five of these microorganisms are able to metabolise, in addition to glucose, most of the pentoses obtained after the hydrolysis of wheat straw by the application of a mixture of hemicellulolytic and cellulolytic enzymes. The highest overall ethanol yield was obtained with the yeast Pachysolen tannophilus. Its application in combination with the best process configuration yielded 163 mg ethanol per gram of raw wheat straw, which was between 23 and 35 % greater than the yields typically obtained with a conventional bioethanol process, in which wheat straw is pretreated using steam explosion and fermented with the yeast Saccharomyces cerevisiae. 相似文献
14.
Murthy GS Johnston DB Rausch KD Tumbleson ME Singh V 《Applied biochemistry and biotechnology》2012,166(1):87-111
Ethanol from corn is produced using dry grind corn process in which simultaneous saccharification and fermentation (SSF) is
one of the most critical unit operations. In this work an optimal controller based on a previously validated SSF model was
developed by formulating the SSF process as a Bolza problem and using gradient descent methods. Validation experiments were
performed to evaluate the performance of optimal controller under different process disturbances that are likely to occur
in practice. Use of optimal control algorithm for the SSF process resulted in lower peak glucose concentration, similar ethanol
yields (13.38±0.36% v/v and 13.50±0.15% v/v for optimally controlled and baseline experiments, respectively). Optimal controller
improved final ethanol concentrations as compared to process without optimal controller under conditions of temperature (13.35±1.28
and 12.52±1.19% v/v for optimal and no optimal control, respectively) and pH disturbances (12.65±0.74 and 11.86±0.49% v/v
for optimal and no optimal control, respectively). Cost savings due to lower enzyme usage and reduced cooling requirement
were estimated to be up to $1 million for a 151 million L/yr (40 million gal/yr) dry grind plant. 相似文献
15.
Yongming Zhu Tae Hyun Kim Y. Y. Lee Rongfu Chen Richard T. Elander 《Applied biochemistry and biotechnology》2006,130(1-3):586-598
A novel method of producing food-grade xylooligosaccharides from corn stover and corn cobs was investigated. The process starts
with pretreatment of feedstock in aqueous ammonia, which results delignified and xylan-rich substrate. The pretreated substrates
are subjected to enzymatic hydrolysis of xylan using endoxylanase for production of xylooligosaccharides. The conventional
enzyme-based method involves extraction of xylan with a strong alkaline solution to form a liquid intermediate containing
soluble xylan. This intermediate is heavily contaminated with various extraneous components. A costly purification step is
therefore required before enzymatic hydrolysis. In the present method, xylan is obtained in solid form after pretreatment.
Water-washing is all that is required for enzymatic hydrolysis of this material. The complex step of purifying soluble xylan
from contaminant is essentially eliminated.
Refining of xylooligosaccharides to food-grade is accomplished by charcoal adsorption followed by ethanol elution. Xylanlytic
hydrolysis of the pretreated corn stover yielded glucan-rich residue that is easily digestible by cellulase enzyme. The digestibility
of the residue reached 86% with enzyme loading of 10 filter paper units/g-glucan. As a feedstock for xylooligosaccharides
production, corn cobs are superior to corn stover because of high xylan content and high packing density. The high packing
density of corn cobs reduces water input and eventually raises the product concentration. 相似文献
16.
John J. Fenske Andrew Hashimoto Michael H. Penner 《Applied biochemistry and biotechnology》1998,73(2-3):145-157
The relative toxicity of the combined nonxylose components in prehydrolysates derived from three different lignocellulosic
biomass feedstocks was determined. One woody (poplar) and two herbaceous (corn stover and switchgrass) feedstocks were dilute-acid
pretreated under temperature and acid conditions chosen to optimize xylose recovery in the liquid prehydrolysate; xylose yields
averaged 96,89,and 87% of theoretical for switchgrass,corn stover,and poplar,respectively. Prehydrolysates from each feedstock
were neutralized,adjusted to equivalent xylose concentrations,and bioassayed for toxicity,using a standardized fermentation
protocol withPichia stipitis NRRL 11545. Full time-courses for ethanol production (30-60 h) clearly illustrate the distinct inhibitory effects of prehydrolysates
from different feedstocks. The relative toxicity of the prehydrolysates,ranked in order of decreasing toxicity,is poplar-derived
prehydrolysates > switchgrass-derived prehydrolysates > corn stover-derived prehydrolysates. The inhibition of ethanol production
appeared to be the result of a general slowdown of yeast metabolism,rather than the result of the production of alternative,
nonethanol end products. Ethanol yields averaged 74,83,and 88% of control values for poplar,switchgrass,and corn stover prehydrolysates,
respectively. Volumetric ethanol productivities (g ethanol L/h) averaged 32,70,and 102% of control values for poplar,switchgrass,and
corn stover prehydrolysates,respectively. Ethanol productivities correlated closely with acetate concentrations in the prehydrolysates;
however, regression lines correlating acetate concentrations and ethanol productivities were found to be feedstock-dependent.
Oregon State University Agricultural Experiment Station Technical Publication Number 11114 相似文献
17.
Soaking in aqueous ammonia at moderate temperatures was investigated as a method of pretreatment for enzymatic hydrolysis as well as simultaneous saccharification and cofermentation (SSCF) of corn stover. The method involves batch treatment of the feedstock with aqueous ammonia (15-30 wt%) at 40-90 degrees C for 6-24 h. The optimum treatment conditions were found to be 15 wt% of NH(3), 60 degrees C, 1:6 of solid-to-liquid ratio, and 12 h of treatment time. The treated corn stover retained 100% glucan and 85% of xylan, but removed 62% of lignin. The enzymatic digestibility of the glucan content increased from 17 to 85% with 15 FPU/g-glucan enzyme loading, whereas the digestibility of the xylan content increased to 78%. The treated corn stover was also subjected to SSCF test using Spezyme-CP and recombinant Escherichia coli (KO11). The SSCF of the soaking in aqueous ammonia treated corn stover resulted in an ethanol concentration of 19.2 g/L from 3% (w/v) glucan loading, which corresponds to 77% of the maximum theoretical yield based on glucan and xylan. 相似文献
18.
Tracy P. Houghton Daniel M. Stevens Peter A. Pryfogle Christopher T. Wright Corey W. Radtke 《Applied biochemistry and biotechnology》2009,153(1-3):4-10
The compositional quality of different lignocellulosic feedstocks influences their performance and potential demand at a biorefinery. Many analytical protocols for determining the composition or performance characteristics of biomass involve a drying step, where the drying temperature can vary depending on the specific protocol. To get reliable data, it is important to determine the correct drying temperature to vaporize the water without negatively impacting the compositional quality of the biomass. A comparison of drying temperatures between 45 °C and 100 °C was performed using wheat straw and corn stover. Near-infrared (NIR) spectra were taken of the dried samples and compared using principal component analysis (PCA). Carbohydrates were analyzed using quantitative saccharification to determine sugar degradation. Analysis of variance was used to determine if there was a significant difference between drying at different temperatures. PCA showed an obvious separation in samples dried at different temperatures due to sample water content. However, quantitative saccharification data shows, within a 95% confidence interval, that there is no significant difference in sugar content for drying temperatures up to 100 °C for wheat straw and corn stover. 相似文献
19.
Ethanol fermentation of various pretreated and hydrolyzed substrates at low initial pH 总被引:1,自引:0,他引:1
Kádár Z Maltha SF Szengyel Z Réczey K de Laat W 《Applied biochemistry and biotechnology》2007,137(1-12):847-858
Lignocellulosic materials represent an abundant feedstock for bioethanol production. Because of their complex structure pretreatment is necessary to make it accessible for enzymatic attack. Steam pretreatment with or without acid catalysts seems to be one of the most promising techniques, which has already been applied for large variety of lignocellulosics in order to improve enzymatic digestibility. During this process a range of toxic compounds (lignin and sugar degradation products) are formed which inhibit ethanol fermentation. In this study, the toxicity of hemicellulose hydrolysates obtained in the steam pretreatment of spruce, willow, and corn stover were investigated in ethanol fermentation tests using a yeast strain, which has been previously reported to have a resistance to inhibitory compounds generated during steam pretreatment. To overcome bacterial contamination, fermentations were carried out at low initial pH. The fermentability of hemicellulose hydrolysates of pretreated lignocellulosic substrates at low pH gave promising results with the economically profitable final 5 vol% ethanol concentration corresponding to 85% of theoretical. Adaptation experiments have shown that inhibitor tolerance of yeast strain can be improved by subsequent transfer of the yeast to inhibitory medium. 相似文献
20.
Improving the quality of cellulosic ethanol feedstocks through breeding and genetic manipulation could significantly impact
the economics of this industry. Attaining this will require comprehensive and rapid characterization of large numbers of samples.
There are many similarities between improving corn silage quality for dairy production and improving feedstock quality for
cellulosic ethanol. It was our objective to provide insight into what is needed for genetic improvement of cellulosic feedstocks
by reviewing the development and operation of a corn silage breeding program. We discuss the evolving definition of silage
quality and relate what we have learned about silage quality to what is needed for measuring and improving feedstock quality.
In addition, repeatability estimates of corn stover traits are reported for a set of hybrids. Repeatability of theoretical
ethanol potential measured by near-infrared spectroscopy is high, suggesting that this trait may be easily improved through
breeding. Just as cell wall digestibility has been factored into the latest measurements of silage quality, conversion efficiency
should be standardized and included in indices of feedstock quality to maximize overall, economical energy availability. 相似文献