Dry Corn Stover Research Articles

Pilot-scale acetone-butanol-ethanol fermentation from corn stover

Biobutanol is an advanced biofuel that can be produced from excess lignocellulose via acetone-butanol-ethanol (ABE) fermentation. Although significant technological progress has been made in this field, attempts at large-scale lignocellulosic ABE production remain scarce. In this study, 1 m3 scale ABE fermentation was investigated using high inhibitor tolerance Clostridium acetobutylicum ABE-P1201 and steam-exploded corn stover hydrolysate (SECSH). Before expanding the fermentation scale, the detoxification process for SECSH was simplified by process engineering. Results revealed that appropriate pH management during the fed-batch cultivation could largely decrease the inhibition of the toxic components in undetoxified SECSH to the solventogenesis phase of the ABE-P1201 strains, avoiding “acid crash”. Therefore, after naturalizing the pH by Ca(OH)2, the undetoxified SECSH, without removal of the solid components, reached 17.68 ± 1.30 g/L of ABE production with 0.34 ± 0.01 g/g of yield in 1 L scale bioreactor. Based on this strategy, the fermentation scale gradually expanded from laboratory-scale apparatus to pilot-scale bioreactors. Finally, 17.05 ± 1.20 g/L of ABE titer and 0.32 ± 0.01 g/g of ABE yield were realized in 1 m3 bioreactor, corresponding to approximately 145 kg of ABE production from 1 t of dry corn stover. The pilot-scale ABE fermentation demonstrated excellent stability during repeated operations. This study provided a simplified ABE fermentation strategy and verified the feasibility of the pilot process, providing tremendous significance and a solid foundation for the future industrialization of second-generation ABE plants.

Integrated strategies for furfural production and lignocellulose fractionation in aqueous deep eutectic solvents

The current biomass refinery pretreatment using deep eutectic solvents (DES) has primarily focused on downstream utilization of cellulose and lignin, while often overlooking the potential of hemicellulose. Herein, an innovative and integrated strategy was proposed for simultaneous production of furfural (FF) and fractionation of lignin and cellulose from biomass using the same aqueous DES. To achieve this goal, response surface methodology (RSM) was employ to optimize the dilute hydrochloric acid (HA) pretreatment of corn stover, a representative of lignocellulosic material, ensuring complete removal of hemicellulose. The resulting hemicellulose hydrolysate was then efficiently converted into FF in aqueous DES system, achieving an impressive yield of 72.82 %. By introducing MgCl2 as a catalyst, the FF yield soared to an exceptional 86.94 %. Furthermore, a plausible mechanism was elucidated for the conversion of hemicellulose to FF in the aqueous DES. Concurrently, the solid residue resulting from the dilute HA pretreatment was fractionated using the same aqueous DES, successfully extracting cellulose and lignin fractions. Notably, the separated cellulose solid residue exhibited an outstanding digestion efficiency of 96.3 % after 72 h of enzymatic hydrolysis at 30 FPU/g, as confirmed through meticulous FTIR analyses. In addition, an advanced 2D-HSQC NMR technique was utilized to unveil the intricate structure of the obtained lignin, revealing a guaiacol-syringyl-p-hydroxyphenyl (G-S-H) type lignin enriched with abundant CH3O- and β-O-4 linkages. A mass balance analysis showed the production of 14.0 g FF, 31.9 g glucose and 14.2 g lignin from 100 g dry corn stover. This state-of-the-art approach presented not only pioneers a novel avenue for the concurrent production of FF but also offers a sustainable and eco-friendly method for the fractionation of lignin and cellulose using DES solvents.

Biorefining of corn stover for efficient production of bioethanol, biodiesel, biomethane, and value-added byproducts

The present study investigated an integrated biorefinery that employed corn stover as the feedstock for sustainable bioethanol, biodiesel, biogas, chitosan, glycerol, and animal feed production. Corn stover was initially subjected to dilute acid pretreatment (1.8 % v/v H2SO4, 121 °C, and 22 min) followed by enzymatic hydrolysis with a commercial cellulase (37 °C, 72 h) to promote the release of glucose (∼93 wt%) and xylose (∼89 wt%). Mucor indicus fungus was then employed to convert the released sugars into bioethanol, glycerol, and fungal biomass with yields of 0.38 g g−1, 36 mg g−1, and 0.51 g g−1, respectively. The biomass of M. indicus was processed to extract chitosan (6 mg g−1 fungal biomass) and lipids (297 mg g−1 fungal biomass). The lipid was subsequently converted to biodiesel via transesterification in the presence of HCl/ MeOH with the yield of 0.54 g g−1 fungal lipid. The defatted biomass residue was then converted to biogas with 81 % theoretical yield through anaerobic digestion. To ensure process circularity, the nutritional values of pretreated and hydrolyzed corn stover were also investigated with their suitability as livestock. It was determined that 158.1 thousand tons of dry corn stover, which was annually collectible in Iran, could be used for the production of 137.6 kg chitosan, 10.4 ton animal feed, 870.0 kg glycerol, 40.7 million litters ethanol, 2.8 million m3 biodiesel, and 449.2 million m3 biomethane. The utilization of the produced ethanol, biodiesel, and biomethane in transporting sector was shown to have the potential of facilitating 4.3 million tons of equivalent carbon dioxide and a 197.8 million dollars reduction of associated social costs.

The Effectiveness of Organic Fertilizer Granules for Increasing Sweet Corn Production on Acid Dryland In Bogor District

Acid dry land generally has limiting factors of higher acidity and low nutrients availibity, so that has low productivity. However, the appropriate inputs have productivity to be better. Research on effectivness of granular organic fertilizers (GOF) to increase sweet corn production has been carried out on dry land in Bogor Regency. The purpose research was to determine the effect GOF of plant growth and enhancment production of sweet corns in acid dry land. This study used a Completely Randomized Block Design with ten treatments and three replications. The results showed that the application of GOF dose 200 kg/ha could increasing soil pH. This improvement in soil chemical properties was followed by increased growth and production of sweet corn. Besides increase the plant growth, GOF made more efficiency 25% of anorganic fertilizer usage. The combination treatment of granular organomineral fertilizers dose 600 kg/ha and NPK recommendation 75% fertilizers increase plant growth such as plant height (124,52%), number of leaves (49%), and plant stem diameter (84,3%). The combination treatment of granular organomineral fertilizers dose 200 – 400 kg/ha and NPK recommendation 75% fertilizers increase sweet corn production such fresh cobs production (345%) and dry corn stover (345%). RAE value is >100% in each GOF treatment, which is the fertilizer effective to increase the sweet corn crops. The optimum yield of maize is 17,45 ton/ha could be obtained with the application of granular organomineral fertilizers dose 275 kg/ha.

Re-examination of dilute acid hydrolysis of lignocellulose for production of cellulosic ethanol after de-bottlenecking the inhibitor barrier

Dilute acid hydrolysis of lignocellulose biomass had been used for production of cellulosic ethanol since 1940 s. The major technical barrier is the acid catalyzed dehydration of monosaccharides to furan aldehydes (furfural and 5-hydroxymethylfurfural), resulting in the high loss of fermentable sugars and significant inhibition on the fermentability of ethanologenic strains. This study re-examined the dilute acid hydrolysis of corn stover and cellulosic ethanol fermentation after a novel biodetoxification approach was introduced to de-bottleneck the inhibitor barrier. The cocktail of sulfuric acid, phosphoric acid and oxalic acid hydrolyzed corn stover to the 51.1 g/L of glucose (0.50 g/g cellulose) and 18.1 g/L of xylose (0.22 g/g xylan). The furfural, 5-hydroxymethylfurfural and acetic acid in the corn stover hydrolysate were completely removed by Paecilomyces variotii FN89, leading to the successful ethanol fermentation of 24.2 g/L, corresponding to 72.6 kg per metric ton of dry corn stover. No wastewater streams, solid wastes and toxic compounds were generated in hydrolysis, biodetoxification and fermentation. The techno-economic evaluations suggest that the cost reduction of replacing cellulase enzyme with cheap acid catalysts compensated the partial ethanol loss of sugar conversion to inhibitors (21.5–89.1%). The re-examination of acid hydrolysis process reveals that a substantial breakthrough in highly active and selective acid catalyst is required for acid hydrolysis to compete with enzymic hydrolysis for cellulosic ethanol fermentation.

Bioethanol from corn stover – Integrated environmental impacts of alternative biotechnologies

The environmental impact potentials of producing bioethanol from corn stover were systematically assessed by life cycle assessment using datasets reported in the literature. The 15% best datasets with respect to global warming potential for seven different technological configurations were extracted from a published database reviewing 474 publications on converting corn stover to bioethanol. A total of 10 impact categories were evaluated. The impacts included both environmental loads and savings, and generally ranged from −0.1 to 0.1 person-equivalent per ton of dry corn stover for most non-toxic impacts and −0.2 to 0.5 person-equivalent for toxic impacts. Fossil fuel substitution with bioethanol provided savings in most impact categories, and so did the energy recovered from the residues, while enzyme production was a significant load. The treatment and discharge of effluent from the liquid residues may constitute a significant load to the environment. Based on the cumulative probabilities of overall environmental performance together with the bioethanol amount produced, the prioritisation of technologies for further development should be as follows: steam explosion (S4) and ammonia-based (S6) technologies as the highest priorities with approximately 100% and 40% probabilities to have savings in non-toxic and toxic impacts, respectively; acid (S1), alkaline (S2) and fungi (S7) technologies as medium priorities and solvent-based (S3) and liquid hot water (S5) technologies have the lowest priorities. We suggest the integration of life cycle assessment modelling to the research and development of biofuel production from biomass waste to ensure that the technologies being developed for full-scale applications are sustainable.

An integrated and optimized process for cleaner production of ethanol and biodiesel from corn stover by Mucor indicus

A two-stage process was successfully developed for biodiesel and ethanol production from corn stover using zygomycetes fungus Mucor indicus. Dilute-acid pretreatment followed by enzymatic saccharification was applied to release the maximum amount of sugars (glucose and xylose) from the lignocellulosic structure of corn stover. Dilute-acid hydrolysis was optimized by a response surface design. Under the optimal reaction conditions (i.e., 1.8% v/v H2SO4, 121 °C for 22 min), the hydrolysis resulted in the production of 270 g glucose per kg of dry corn stover (57.8% theoretical yield) and 100 g xylose per kg of dry corn stover (84.0% theoretical yield). Validation of the model exhibited proper fit between predicted and observed values of glucose and xylose concentrations: 91.4% regression adjustment for xylose and 98.2% for glucose. In the first stage, cells fermented the enzymatic hydrolysate to the maximum amount of 74.5% (0.38 g g−1) ethanol as the main product. In the second stage, the dilute-acid hydrolysate was used for lipid accumulation in the fungal cells of the first stage fermentation. The hydrolysates were used without detoxification since the fungus is among the most resistant microorganisms to the inhibitors available in the acid hydrolysates. Effects of addition of different nutrient sources, including fungal extract and yeast extract along with mineral salts, were also investigated to maximize lipid yield. Overall, 21.4 g ethanol and 2.2 g biodiesel (obtained from 4.00 g accumulated lipid) were produced from 100 g dry corn stover.

Bioethanol from corn stover – Global warming footprint of alternative biotechnologies

Bioethanol from residual corn stover could contribute to lowering CO2 loads within the transport sector, if used as an amendment to gasoline. We modelled by life cycle assessment and Monte Carlo simulation seven different technological configurations for producing bioethanol from corn stover based on consistent mass flows and estimated ethanol production extracted from 141 datasets of reasonable quality. By parametrizing key processes and determining their statistical distribution based on actual data, we were able to estimate the Global Warming Potential (GWPs) for all the alternative technologies on a system level. Most of the individual cases showed a net saving in GWP when the savings obtained from recovering energy from anaerobic digestion of the liquid residues and incineration of the solid residues were included. The net savings could in some cases be as high as 900 ∼ 1200 kg CO2-eq/t dry corn stover solids. If the residues were not subject to energy recovery, the production of bioethanol and use in gasoline would be a net load to global warming in more than 50% of the technological configurations. The “best-practice”, defined as the top 15% cumulative probability with respect to GWP, suggests that technologies based on steam explosion and ammonia-based pretreatment appear statistically the most promising and could contribute, with residue energy recovery, to GWP savings of 850–1050 kg CO2-eq/t dry corn stover solids and produce in the range 178–216 kg of bioethanol. This paper provides insights into the key parameters for bioethanol production from corn stover and suggests areas for further research.

The Integrated Process of Microbial Ensiling and Hot-Washing Pretreatment of Dry Corn Stover for Ethanol Production

In this study, we used dry corn stover (DCS) silage as feedstock to produce ethanol using hot-washing treatment (HWT) followed by prehydrolysis and fed-batch simultaneous saccharification and fermentation (FD-SSF) using cellulase and Saccharomyces cerevisiae. The inoculants product for ensiling of DCS was composed of lactic acid-producing organisms, such as Lactobacillus casei, Lactobacillus fermentum and Enterococcus durans. Moreover, the appropriate condition was selected by the dynamic analysis of silage quality. Among test conditions, the pH value (4.22), pretreatment time (4 week) and the content of lactic acid in DCS silage (4.32%) could be considered as important indicators of the success of microbial ensiling. The 16S rRNA gene-based pyrosequencing was used to analyze the community of the resulting silage, and the results indicated that Lactobacillus was the advantageous species. The observed glass transition temperature (Tg) value for DCS silage occurred at a temperature of 124.2 °C (Tmid). DCS silage was hydrothermally treated at temperature of Tg for 20 min. It was proved that biomass can be pretreated for cellulosic ethanol production by the integrated process of microbial ensiling and HWT. Ethanol fermentation of HWT-treated (at 30% glucan loading) DCS silage hydrolyzate (resulting in 61.92 g/L ethanol at 59.15% metabolic yield of FD-SSF) was reported in this work.

Fermentation quality and nutritive value of fresh and fermented total mixed rations containing Chinese wildrye or corn stover

AbstractNutritive value of fresh or fermented total mixed ration (TMR) containing Chinese wildrye (Leymus chinensis (Trin.) Tzval.) or dry corn (Zea mays L.) stover was determined. The experimental treatments included fermentation and dietary roughage. The fermentation treatments included fresh and fermented TMR, while the dietary roughage treatments included Chinese wildrye and corn stover. Compared to the fresh TMR, the fermented TMR had higher (P < 0.05) contents of ether extract, lactic acid, acetic acid and ammonia‐nitrogen (N) but lower (P < 0.05) organic matter, non fibrous carbohydrate and neutral detergent fiber, and inhibited growth of molds in silages; moreover, the fermented TMR increased (P < 0.05) the digestibility of ether extract and neutral detergent fiber, and tended to increase (P < 0.05) the digestibility of acid detergent fiber, but also increased the concentration of ruminal total volatile fatty acid and valeric acid at 2 h of feeding, and ammonia‐N at 2 or 4 h of feeding. The silage with 10 mm corn stover had a higher (P < 0.05) lactic acid content, and reduced (P < 0.05) losses of non fibrous carbohydrate during fermentation compared with 50 mm treatment. Almost all chopped‐corn stover TMR had similar nutrient digestibility to Chinese wildrye. Among the eight TMRs, the fermented TMR with 10 mm corn stover had the highest intake ration of dry matter, while the fermented TMR with Chinese wildrye was the lowest. These results suggest that fermentation inhibit growth of molds in silage, decrease neutral detergent fiber, and then improve the nutrient digestibility. Chopped corn stover TMR had similar nutrient digestibility to Chinese wildrye TMR, and could replace Chinese wildrye in TMRs for ruminants.

Impact of ammonia fiber expansion (AFEX) pretreatment on energy consumption during drying, grinding, and pelletization of corn stover

ABSTRACTPretreatment and densification of biomass can increase the viability of bioenergy production by providing a feedstock that is readily hydrolyzed and able to be transported over greater distances. Ammonia fiber expansion (AFEX™) is one such method targeted for use at distributed depots to create a value-added and densified feedstock for bioenergy use. However, the pretreatment process results in a high-moisture material that must be dried, further size reduced, and pelletized, all of which are energy-intensive processes. This work quantifies the energy consumption required to dry, grind, and densify AFEX-pretreated corn stover compared to non-pretreated stover and explores the potential of reduced drying as a means to conserve energy. The purpose of this work is to understand whether material property changes resulting from AFEX pretreatment influence the material performance in downstream formatting operations. Material properties, heat balance equations, and a rotary drum dryer model were used to model a commercial-scale rotary drum dryer for AFEX-pretreated corn stover, showing the potential to reduce dryer energy consumption by up to 36% compared to non-pretreated corn stover. Laboratory-measured grinding and pelleting energies were both very sensitive to material moisture content. Overall, the total energy required for drying, grinding, and pelleting amounts to a savings of up to 23 kWh/dry Mg for the AFEX-pretreated material when dried to a low moisture content, equating to up to 0.61 $/Mg savings for gas and electricity. Grinding and pelleting of high-moisture AFEX-pretreated stover was shown to be more costlier than the savings collected through reduced drying. Although the energy and cost savings shown here are modest, the results help to highlight operational challenges and opportunities for continued improvement.

Pilot-Scale Batch Alkaline Pretreatment of Corn Stover

The goal of biomass pretreatment is to increase the enzymatic digestibility of the plant cell wall polysaccharides to produce sugars for upgrading to biofuels. Alkaline pretreatment has the ability to solubilize much of the lignin in biomass while the carbohydrates remain insoluble. With an increased research focus to produce high-value products from lignin, a low molecular weight, lignin-rich stream in a biorefinery is desirable. This work reports on batch alkaline pretreatment of corn stover conducted using a three-factor, two-level central composite experimental design in a pilot-scale reactor to determine the relationship between sodium hydroxide (NaOH) loading, temperature, and anthraquinone (AQ) charge on solids solubilization, component yields, and enzymatic digestibility of the residual solids. Operating conditions were 100 to 140 °C, 40 to 70 mg NaOH/g dry corn stover, and 0.05% to 0.2% (w/w) AQ loading. An enzymatic hydrolysis screening study was performed at 2% cellulose loading. Empirical modeling results showed that NaOH loading and temperature are both significant factors, solubilizing 15% to 35% of the solids and up to 54% of the lignin. Enzymatic hydrolysis of the residual solids produced good monomeric glucose (>90%) and xylose (>70%) yields at the more severe pretreatment conditions. We also found that the AQ charge was not a significant factor at the conditions studied, so efforts to reduce xylan and increase lignin solubilization using this compound were not successful. While good lignin solubilization was achieved, effectively recovering this stream remains a challenge, and demonstrating performance in continuous reactors is still needed.

Bioflocculant production from untreated corn stover using Cellulosimicrobium cellulans L804 isolate and its application to harvesting microalgae.

BackgroundMicroalgae are widely studied for biofuel production. Nevertheless, harvesting step of biomass is still a critical challenge. Bioflocculants have been applied in numerous applications including the low-cost harvest of microalgae. A major bottleneck for commercial application of bioflocculant is its high production cost. Lignocellulosic substrates are abundantly available. Hence, the hydrolyzates of rice stover and corn stover have been used as carbon source to produce the bioflocculant in previous studies. However, the hydrolyzates of biomass required the neutralization of pH before the downstream fermentation processes, and the toxic by-products produced during hydrolysis process inhibited the microbial activities in the subsequent fermentation processes and contaminated the bioflocculant product. Therefore, strains that can secrete plant cell-wall-degrading enzymes and simultaneously produce bioflocculants through directly degrading the lignocellulosic biomasses are of academic and practical interests.ResultsA lignocellulose-degrading strain Cellulosimicrobium cellulans L804 was isolated in this study, which can produce the bioflocculant MBF-L804 using untreated biomasses, such as corn stover, corn cob, potato residues, and peanut shell. The effects of culture conditions including initial pH, carbon source, and nitrogen source on MBF-L804 production were analyzed. The results showed that over 80 % flocculating activity was achieved when the corn stover, corn cob, potato residues, and peanut shell were used as carbon sources and 4.75 g/L of MBF-L804 was achieved under the optimized condition: 20 g/L dry corn stover as carbon source, 3 g/L yeast extract as nitrogen source, pH 8.2. The bioflocculant MBF-L804 contained 68.6 % polysaccharides and 28.0 % proteins. The Gel permeation chromatography analysis indicated that the approximate molecular weight (MW) of MBF-L804 was 229 kDa. The feasibility of harvesting microalgae Chlamydomonas reinhardtii and Chlorella minutissima using MBF-L804 was evaluated. The highest flocculating efficiencies for C. reinhardtii and C. minutissima were 99.04 and 93.83 %, respectively.ConclusionsThis study shows for the first time that C. cellulans L804 can directly convert corn stover, corn cob, potato residues and peanut shell into the bioflocculants, which can be used to effectively harvest microalgae.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-015-0354-4) contains supplementary material, which is available to authorized users.

Integrated Production of Xylonic Acid and Bioethanol from Acid-Catalyzed Steam-Exploded Corn Stover.

High-efficiency xylose utilization is one of the restrictive factors of bioethanol industrialization. However, xylonic acid (XA) as a new bio-based platform chemical can be produced by oxidation of xylose with microbial. So, an applicable technology of XA bioconversion was integrated into the process of bioethanol production. After corn stover was pretreated with acid-catalyzed steam-explosion, solid and liquid fractions were obtained. The liquid fraction, also named as acid-catalyzed steam-exploded corn stover (ASC) prehydrolyzate (mainly containing xylose), was catalyzed with Gluconobacter oxydans NL71 to prepare XA. After 72 h of bioconversion of concentrated ASC prehydrolyzate (containing 55.0 g/L of xylose), the XA concentration reached a peak value of 54.97 g/L, the sugar utilization ratio and XA yield were 94.08 and 95.45 %, respectively. The solid fraction was hydrolyzed to produce glucose with cellulase and then fermented with Saccharomyces cerevisiae NL22 to produce ethanol. After 18 h of fermentation of concentrated enzymatic hydrolyzate (containing 86.22 g/L of glucose), the ethanol concentration reached its highest value of 41.48 g/L, the sugar utilization ratio and ethanol yield were 98.72 and 95.25 %, respectively. The mass balance showed that 1 t ethanol and 1.3 t XA were produced from 7.8 t oven dry corn stover.

A self-sustaining advanced lignocellulosic biofuel production by integration of anaerobic digestion and aerobic fungal fermentation

High energy demand hinders the development and application of aerobic microbial biofuel production from lignocellulosic materials. In order to address this issue, this study focused on developing an integrated system including anaerobic digestion and aerobic fungal fermentation to convert corn stover, animal manure and food wastes into microbial lipids for biodiesel production. Dairy manure and food waste were first anaerobically digested to produce energy and solid digestate (AD fiber). AD fiber and corn stover were then processed by a combined alkali and acid hydrolysis, followed by fungal lipid accumulation. The integrated process can generate 1L biodiesel and 1.9kg methane from 12.8kg dry dairy manure, 3.1kg dry food wastes and 12.2kg dry corn stover with a positive net energy of 57MJ, which concludes a self-sustaining lignocellulosic biodiesel process and provides a new route to co-utilize corn stover and organic wastes for advanced biofuel production.

Corn Stover Bioconversion by Green Liquor Pretreatment and a Selected Liquid Fermentation Strategy

Green liquor pretreatments and different liquid-fermentation strategies were tested to establish an effective ethanol production process from corn stover. After pretreatment and enzymatic hydrolysis, 329.7 g of glucose and 126.3 g of xylose were obtained from 1,000 g of dry corn stover. The primary aim of this work was to test the fermentability of the enzymatic hydrolysate of green liquor-pretreated corn stover, for no fermentation has been done on the enzymatic hydrolysate of green liquor-pretreated corn stover before. Three liquid-fermentation strategies, including sequential fermentation, co-fermentation, and co-culture, were carried out and compared to select an appropriate fermentation strategy from green liquor-pretreated corn stover. Among the different liquid-fermentation strategies, sequential fermentation yielded the highest ethanol production (210.7 g ethanol/1,000 g corn stover). Using the sequential fermentation strategy, glucose fermentation by Saccharomyces cerevisiae and ethanol distillation was completed prior to xylose fermentation by Pichia stipitis, so that the separate utilization of glucose and xylose ensured that each fermentation stage used the suitable microorganism, permitting high ethanol yields. Sequential fermentation was thus considered to be the most promising liquid-fermentation strategy for ethanol production from green liquor-pretreated corn stover.

Use of wood-based materials in beef bedded manure packs: 1. Effect on ammonia, total reduced sulfide, and greenhouse gas concentrations.

The objectives of this study were to determine the effect of using corn stover or three different wood-based bedding materials (kiln-dried pine wood chips, dry cedar chips, or green cedar chips) on airborne concentrations of NH, total reduced sulfides (TRS), CO, CH, and NO above lab-scaled bedded manure packs. Four bedded packs of each bedding material were maintained for two 42-d periods. Airborne NH, TRS, CO, CH, and NO were measured weekly. Bedded packs containing dry or green cedar had lower concentrations of NH (350.8 and 357.3 mg m, respectively; < 0.05) than bedded packs containing pine chips or corn stover (466.0 and 516.7 mg m, respectively). Airborne CO was also lower from bedded packs containing dry and green cedar (1343.7 and 1232.3 mg m, respectively; < 0.001) compared with bedded packs containing pine chips or corn stover (2000.2 and 1659.8 mg m, respectively). Air samples from bedded packs containing green cedar chips had a higher ( < 0.01) concentration of CH than bedded packs containing dry cedar chips, corn stover, or pine chips at Day 35 and 42. Initially, TRS concentration was similar among all bedding materials; at 28 to 42 d, TRS was higher ( < 0.001) from bedded packs containing the cedar products. Airborne NO was similar ( = 0.51) for all bedding materials. Pine chips and cedar products can be adequate substitutes for corn stover in deep-bedded barns, but cedar bedding may need to be removed more frequently.

Improved Enzymatic Hydrolysis of Corn Stover by Green Liquor Pretreatment and a Specialized Enzyme Cocktail

An effective strategy for sugar production from corn stover was established through a combination of green liquor pretreatment (8% total titratable alkali charge, 40% sulfidity, 140 °C, and 1 h) and enzymatic hydrolysis with a specialized enzyme cocktail. Green liquor pretreatment was demonstrated as an effective first step for sugar production due to the selective removal of lignin (39.70%), high carbohydrate recovery yield (81.53%), and obvious enhancement of enzymatic hydrolysis after pretreatment. When a specialized enzyme cocktail (cellulase, β-glucosidase, and xylanase at a ratio of 1:1.88:6.61, supplemented with 0.05 g of PEG 6000 per g of glucan) was applied, near-theoretical hydrolysis yield was achieved (glucan hydrolysis yield of 93.53% and xylan hydrolysis yield of 86.00%). A total fermentable sugar production of 50.14 g was obtained per 100 g of dry corn stover, including 36.08 g of glucose and 14.06 g of xylose.

Single reactor conversion of corn stover biomass to C5–C20 furanic biocrude oil using sulfonic acid functionalized Brönsted acidic ionic liquid catalysts

Cellulose (DP∼450) and dry corn stover powder were converted to furanic biocrude oils in a single reactor operation by heating with excess acetone in the presence of Bronsted acidic ionic liquid catalysts. Two Bronsted acidic ionic liquid catalysts, 1-(1-propylsulfonic)-3-methylimidazolium chloride (BAIL-1) and 1-(4-sulfonic-benzyl)-3-methylimidazolium chloride (BAIL-2), were compared for biocrude oil synthesis from cellulose and dry corn stover. Catalyst BAIL-1 showed slightly better activity in all experiments, where cellulose samples produced 52.9 mg biocrude oil/100 mg of cellulose, and corn stover produced 34.2 mg biocrude oil/100 mg of corn stover by heating at 120 °C for 3 h. Biocrude oil formed in the novel process is mainly a complex mixture of aldol condensation products of acetone with biomass-derived furans, furfural and 5-hydroxymethylfurfural.

Dilute Sulfuric Acid Pretreatment and Enzymatic Hydrolysis of Corn Stover into Fermentable Sugars

The pretreatment of corn stover with dilute sulfuric acid has been investigated by varying the acid concentration (0.5%-1.25%(w/w)) and the temperature (130-160°C). The pretreatment is aimed at improving enzymatic hydrolysis and increasing the fermentability of the biomass. Given the overall sugar yield, the most favourable pretreatment condition was performed with 0.75% sulfuric acid at 150°C for 30min and then with an enzyme loading of cellulase 15 FPU per gram of cellulose, and it resulted in a total of 49.74g glucose and xylose from 100g dry corn stover. The fiber physical feature, structure and property of pretreated residues were studied with Scanning Electron Microscope (SEM) and Fourier transform infrared spectroscopy. The SEM pictures indicated that the biomass structure was deformed and its fibers were exposed by the pretreatment. FTIR study showed that lignin and hemicellulose were partially removed during the diluted sulfuric acid pretreatment.