青贮对柳枝稷制取燃料乙醇转化过程的影响

青贮是一种传统的生物质原料保存方法,广泛应用于纤维素乙醇炼制领域尚需要考察其对原料品质和下游乙醇转化过程的影响。文中以秋季(初、中和末)收割的柳枝稷为原料,通过青贮、高温水热(LHW)预处理、纤维素酶水解和同步糖化与发酵(SSF)实验对上述问题予以回答。结果显示,秋季初收割的柳枝稷以不同湿度青贮后pH均小于4.0,干重损失小于2%,各主要成分与青贮前相比无明显变化;LHW预处理中青贮样品半纤维素水解率普遍高于未贮存样品,但青贮同样使原料获得了更高的发酵抑制物产生水平;青贮柳枝稷葡萄糖、木糖和半乳糖产量(预处理+酶水解)高于未贮存柳枝稷;经过168 h的SSF,青贮样品乙醇浓度为12.1 g/L,未贮存的秋季初、秋季中和秋季末柳枝稷为底物的浓度分别为10.3 g/L、9.7 g/L和10.6 g/L。综上,青贮有助于提高柳枝稷LHW预处理效率、酶水解率和乙醇产量。     

Influence of moisture content on microbial activity and silage quality during ensilage of food processing residues

Seasonally produced biomass such as sugar beet pulp (SBP) and tomato pomace (TP) needs to be stored properly to meet the demand of sustainable biofuel production industries. Ensilage was used to preserve the feedstock. The effect of moisture content (MC) on the performance of ensilage and the relationship between microorganism activities and MC were investigated. For SBP, MC levels investigated were 80, 55, 30, and 10% on a wet basis. For TP, MC levels investigated were 60, 45, 30, and 10%. Organic acids, ethanol, ammonia, pH and water soluble carbohydrates (WSC) were measured to evaluate the silage quality. Ensilage improved as the MC decreased from 80 to 55% for SBP and from 60 to 45% for TP. When the MC decreased to 30%, a little microbial activity was detected for both feedstocks. Storage at 10% MC prevented all the microbial activity. The naturally occurring microorganisms in TP were found to preserve TP during silage and were isolated and determined by polymerase chain reaction (PCR). The results suggest that partial drying followed by ensilage may be a good approach for stabilization of food processing residues for biofuels production.     

Corn stover feedstock trials to support predictive modeling

To be sustainable, feedstock harvest must neither degrade soil, water, or air resources nor negatively impact productivity or subsequent crop yields. Simulation modeling will help guide the development of sustainable feedstock production practices, but not without field validation. This paper introduces field research being conducted in six states to support Sun Grant Regional Partnership modeling. Our objectives are to (1) provide a fundamental understanding of limiting factor(s) affecting corn (Zea mays L.) stover harvest, (2) develop tools (e.g., equations, models, etc.) that account for those factors, and (3) create a multivariant analysis framework to combine models for all limiting factors. Sun Grant modelers will use this information to improve regional estimates of feedstock availability. A minimum data set, including soil organic carbon (SOC), total N, pH, bulk density (BD), and soil‐test phosphorus (P), and potassium (K) concentrations, is being collected. Stover yield for three treatments (0%, 50%, and 90% removal) and concentrations of N, P, and K in the harvested stover are being quantified to assess the impact of stover harvest on soil resources. Grain yield at a moisture content of 155 g kg^?1 averaged 9.71 Mg ha^?1, matching the 2008 national average. Stover dry matter harvest rates ranged from 0 to 7 Mg ha^?1. Harvesting stover increased N–P–K removal by an average of 42, 5, and 45 kg ha^?1 compared with harvesting only grain. Replacing those three nutrients would cost $53.68 ha^?1 based on 2009 fertilizer prices. This first‐year data and that collected in subsequent years is being used to develop a residue management tool that will ultimately link multiple feedstock supplies together in a landscape vision to help develop a comprehensive carbon management plan, quantify corn stover harvest effects on soil quality, and predict regional variability in feedstock supplies.     

Enzyme enhanced solid-state fermentation of kenaf core fiber for storage and pretreatment

Kenaf is an annual fiber crop adaptable to a wide range of climates and soil types. This study investigated the use of kenaf core fiber as a feedstock for enzyme-enhanced fermentation. Triplicate kenaf core fiber samples were treated with enzymes having cellulase:hemicellulase activity ratios of 0:1, 0.015:1, 0.45:1, and 2.54:1 at a rate of 5010 IU/kg dry matter hemicellulase activity, vacuum-sealed, and incubated at 37 degrees C for 21 d. Samples were analyzed for pH, water soluble carbohydrates, organic acids, and hemicellulose and cellulose concentrations. All treatments produced a pH less than 4.0, which is sufficient for stable storage. Treatments with 2.54:1 and 0.45:1 produced the highest water soluble carbohydrate and lactic acid concentrations. Enzymes with no or low cellulase activity produced results similar to the control. Utilizing enzyme mixtures with high cellulase activity is an effective pretreatment method for ensiled kenaf core fiber.     

Availability of corn stover as a sustainable feedstock for bioethanol production

The amount of corn stover that can be sustainably collected is estimated to be 80-100 million dry tonnes/yr (t/yr), a majority of which would be available to ethanol plants in the near term as only a small portion is currently used for other applications. Potential long-term demand for corn stover by non-fermentative applications in the United States is estimated to be about 20 million dry t/yr, assuming that corn stover-based products replace 50% of both hardwood pulp and wood-based particleboard, and that 50% of all furfural production is from corncobs. Hence, 60-80 million dry t/yr of corn stover should be available to fermentative routes. To achieve an ethanol production potential of 11 billion L (3 billion gal) per year (a target level for a non-niche feedstock), about 40% of the harvestable corn stover is needed. This amount should be available as long as the diversion of corn stover to non-ethanol fermentative products remains limited.     

Evaluation of the phytosanitary, fermentative and nutritive characteristics of the silage made from crude artichoke (Cynara scolymus L.) by-product feeding for ruminants

The crude by-product left after industrial processing of artichoke (Cynara scolymus L.) was ensiled in microsilos and sampled at different times. To evaluate its suitability as animal feed, various fermentative, chemical and phytosanitary parameters were determined. The by-product showed a good aptitude for ensilage, having a pleasant smell and good visual characteristics. The DM content was 297 g kg⁻¹, and no effluents were detected. It stabilized after 12 days of ensiling and showed a pH value of 4.1 at the end of the process. Only small losses were detected in its chemical value after the ensiling period. Prometryn was the only phytosanitary product found at day 0 (0.04 ppm a concentration below the maximum amount permitted by law), but was not detected after 12 days of ensilage. It is concluded that the silage by-product can be used as animal feed.     

Multilocation Corn Stover Harvest Effects on Crop Yields and Nutrient Removal

Corn (Zea mays L.) stover was identified as an important feedstock for cellulosic bioenergy production because of the extensive area upon which the crop is already grown. This report summarizes 239 site-years of field research examining effects of zero, moderate, and high stover removal rates at 36 sites in seven different states. Grain and stover yields from all sites as well as N, P, and K removal from 28 sites are summarized for nine longitude and six latitude bands, two tillage practices (conventional vs no tillage), two stover-harvest methods (machine vs calculated), and two crop rotations {continuous corn (maize) vs corn/soybean [Glycine max (L.) Merr.]}. Mean grain yields ranged from 5.0 to 12.0 Mg ha^?1 (80 to 192 bu ac^?1). Harvesting an average of 3.9 or 7.2 Mg ha^?1 (1.7 or 3.2 tons ac^?1) of the corn stover resulted in a slight increase in grain yield at 57 and 51 % of the sites, respectively. Average no-till grain yields were significantly lower than with conventional tillage when stover was not harvested, but not when it was collected. Plant samples collected between physiological maturity and combine harvest showed that compared to not harvesting stover, N, P, and K removal was increased by 24, 2.7, and 31 kg ha^?1, respectively, with moderate (3.9 Mg ha^?1) harvest and by 47, 5.5, and 62 kg ha^?1, respectively, with high (7.2 Mg ha^?1) removal. This data will be useful for verifying simulation models and available corn stover feedstock projections, but is too variable for planning site-specific stover harvest.     

Concentrated HCl Catalyzed 5-(Chloromethyl)furfural Production from Corn Stover of Varying Particle Sizes

5-(Chloromethyl) Furfural (CMF) is a potential chemical building block for replacing petroleum-derived chemicals derived from lignocellulosic feedstocks. In this study, hand harvested corn stover and mechanically forage chopped corn stover was processed in a 1 L hydrolysis reactor to produce CMF in a biphasic, two solvent system. Both 1,2 dichloroethane (DCE) and dichloromethane (DCM) were tested as organic solvents. The results showed that DCE performed better than DCM due to temperature and pressure limitations of the reactor system. Using DCE as the extracting solvent, the effects of solids loading, particle size, and moisture content of the corn stover on the hydrolysis efficiency were determined. One liter acid hydrolysis reactor provides consistent and reproducible yields of 63% CMF from hand harvested corn stover as feedstock at solid loading of 10% wt/v, 100C for 1 h. For the forage chopped corn stover, increasing particle size brings an increase in the feedstock sugar content. Foraged chopped corn stover (FCCS) particle sizes larger than 19 mm (0.75 in.) results in significant reduction in CMF yield from 43 to 35%.     

Nutrient Removal as a Function of Corn Stover Cutting Height and Cob Harvest

One-pass harvest equipment has been developed to collect corn (Zea mays L.) grain, stover, and cobs that can be used as bioenergy feedstock. Nutrients removed in these feedstocks have soil fertility implication and affect feedstock quality. The study objectives were to quantify nutrient concentrations and potential removal as a function of cutting height, plant organ, and physiological stage. Plant samples were collected in 10-cm increments at seven diverse geographic locations at two maturities and analyzed for multiple elements. At grain harvest, nutrient concentration averaged 5.5 g?N kg^?1, 0.5 g?P kg^?1, and 6.2 g?K kg^?1 in cobs, 7.5 g?N kg^?1, 1.2 g?P kg^?1, and 8.7 g?K kg^?1 in the above-ear stover fraction, and 6.4 g?N kg^?1, 1.0 g?P kg^?1, and 10.7 g?K kg^?1 in the below-ear stover fraction (stover fractions exclude cobs). The average collective cost to replace N, P, and K was $11.66 Mg^?1 for cobs, $17.59 Mg^?1 for above-ear stover, and $18.11 Mg^?1 for below-ear stover. If 3 Mg ha^?1 of above-ear stover fraction plus 1 Mg of cobs are harvested, an average N, P, and K replacement cost was estimated at $64 ha^?1. Collecting cobs or above-ear stover fraction may provide a higher quality feedstock while removing fewer nutrients compared to whole stover removal. This information will enable producers to balance soil fertility by adjusting fertilizer rates and to sustain soil quality by predicting C removal for different harvest scenarios. It also provides elemental information to the bioenergy industry.     

The potential for using the needle litter of Scotch pine (Pinus sylvestris L.) as a raw material for particleboard manufacturing

Particleboard panels were made from various wood particle/needle litter of Scotch pine (Pinus sylvestris L.) mixtures bonded with urea formaldehyde resin. Litter was characterized by having higher solubility's in alcohol-benzene, with diluting alkali and hot water, and resulted in lower pH values than those of wood particles. The mechanical properties (modulus of rupture, modulus of elasticity, and internal bond strength) of boards containing up to 6.25% litter were lower than those of panels made from wood particles. However, needle litter usage improved the physical property (thickness swelling) and decay resistance of the panels, significantly. Panels consist of 6.25% and 12.50% needle litter met the minimum EN standard requirements of mechanical properties for general-purposes. Particleboards contain more than 50% needle litter had the required level of thickness swelling for 24 h immersion.     

Environmental profile analysis of particleboard production: a study in a Pakistani technological condition

Purpose

Particleboard is a composite panel comprising small pieces of wood bonded by adhesives. The particleboard industry is growing in Pakistan, but there is little information on the environmental impacts associated with this product. Therefore, the aim of this study was to develop a life cycle assessment of particleboard manufactured in Pakistan and to provide suggestions to improve its environmental profile. The study covers energy use and associated environmental impacts of raw materials and processes during particleboard manufacture in the year 2015–2016.

Methods

The study uses a cradle-to-gate (distribution center) life cycle assessment approach. The reference unit for this study was 1.0 m³ of finished, uncoated particleboard. Primary data from the particleboard mill surveys were combined with secondary database information and modeled using CML 2000 v.2.05 methodology and a cumulative exergy demand indicator present in the SimaPro v.8.3 software.

Results and discussion

The results reveal that urea formaldehyde resin, transportation of raw materials, and finished product distribution had the highest contribution to all the environmental impact categories evaluated. Heavy fuel oil and natural gas consumption was responsible for abiotic depletion, photochemical oxidation, ozone layer depletion, and marine aquatic ecotoxicity impacts. The rotary dryer and hot press were the most important sectors in terms of emissions from the manufacturing process. The total cumulative exergy demand required for manufacturing of 1.0 m³ particleboard was 15,632 MJ-eq, with most of the energy usage associated with non-renewable, fossil fuel sources. A sensitivity analysis was conducted for a reduction in the quantity of urea formaldehyde resin consumed and freight transport distances.

Conclusions

The results indicated that reducing the urea formaldehyde resin use and freight distances could greatly decrease environmental impacts. Most of the surveyed mills did not have emissions control systems, and most of the mills exceed the limits set by the National Environmental Quality Standards of Pakistan. Environmental impact improvements might be attained by reducing quantity of urea formaldehyde resin and transportation freight distances and by installing pollution control devices.

     

The response of sheep to big bale grass silage ensiled with,or supplemented separately with,molassed sugar beet feed

Second cut big bale grass silage was prepared with grass ensiled alone or with added pelleted, molassed sugar beet feed (MSBF) at 32 or 64 g MSBF kg⁻¹ fresh weight of grass. Addition of MSBF at ensilage increased silage dry matter (DM), water soluble carbohydrate and lactic acid concentrations and decreased ammonia concentration. When fed to wether lambs, MSBF addition, whether at ensilage or given separately, variably improved DM intake, live-weight gain and feed conversion efficiency. Ruminal concentrations of ammonia were reduced and acetate molar proportion increased in diets supplemented with MSBF separately compared with the silage only control diet. Animal performance was generally improved by MSBF supplementation with responses to silages made with added MSBF comparable to those from silage supplemented with MSBF at feeding. There was little difference in animal performance between silages made with 32 or 64 g kg⁻¹ MSBF added at ensiling.     

Development of a fluorescence-based method for monitoring glucose catabolism and its potential use in a biomass hydrolysis assay

Background  

The availability and low cost of lignocellulosic biomass has caused tremendous interest in the bioconversion of this feedstock into liquid fuels. One measure of the economic viability of the bioconversion process is the ease with which a particular feedstock is hydrolyzed and fermented. Because monitoring the analytes in hydrolysis and fermentation experiments is time consuming, the objective of this study was to develop a rapid fluorescence-based method to monitor sugar production during biomass hydrolysis, and to demonstrate its application in monitoring corn stover hydrolysis.     

Effect of variety and harvest date on nutritive value and ruminal degradability of ensiled maize ears

The nutritive value of whole crop forage maize is influenced by the proportion of ears and stover in the whole crop and by the nutrient composition and digestibility characteristics of the plant parts. An experiment investigating the impact of variety, harvest date and year on the nutritive value of ensiled maize ears was carried out in three consecutive years (2007, 2008 and 2010). Nine different maize varieties were harvested at three different maturity stages (50, 55 and 60% dry matter (DM) content in the ears). After harvest, ears and stover were ensiled separately and afterwards nutrient composition and ruminal nutrient degradability (organic matter (OM), crude protein (CP) and non-fibre carbohydrates (NFC)) were analysed. Variety had a significant influence on content of CP and effective ruminal degradability (ED) of OM at low passage rates, whereas ED of CP and NFC was not affected by variety. In contrast, harvest date and year significantly influenced nutrient composition and ruminal degradability of ensiled maize ears. The content of NFC increased and the content of fibre components as well as ED of OM, CP and NFC declined with processing maturity of the maize plants. At a passage rate of 5% h^?1, ED of OM declined from 75.9% to 68.4%, ED of CP from 82.5% to 73.8% and ED of NFC from 88.0% to 82.3% between the early and late harvest date. The results of this study indicate that the nutrient composition and ruminal degradability of ensiled maize ears are affected mainly by maturity stage at harvest and by year, whereas variety has only little influence.     

Soil nutrient budgets following projected corn stover harvest for biofuel production in the conterminous United States

Increasing demand for food and biofuel feedstocks may substantially affect soil nutrient budgets, especially in the United States where there is great potential for corn (Zea mays L) stover as a biofuel feedstock. This study was designed to evaluate impacts of projected stover harvest scenarios on budgets of soil nitrogen (N), phosphorus (P), and potassium (K) currently and in the future across the conterminous United States. The required and removed N, P, and K amounts under each scenario were estimated on the basis of both their average contents in grain and stover and from an empirical model. Our analyses indicate a small depletion of soil N (?4 ± 35 kg ha^?1) and K (?6 ± 36 kg ha^?1) and a moderate surplus of P (37 ± 21 kg ha^?1) currently on the national average, but with a noticeable variation from state to state. After harvesting both grain and projected stover, the deficits of soil N, P, and K were estimated at 114–127, 26–27, and 36–53 kg ha^?1 yr^?1, respectively, in 2006–2010; 131–173, 29–32, and 41–96 kg ha^?1 yr^?1, respectively, in 2020; and 161–207, 35–39, and 51–111 kg ha^?1 yr^?1, respectively, in 2050. This study indicates that the harvestable stover amount derived from the minimum stover requirement for maintaining soil organic carbon level scenarios under current fertilization rates can be sustainable for soil nutrient supply and corn production at present, but the deficit of P and K at the national scale would become larger in the future.     

Life Cycle Performance of Cellulosic Ethanol and Corn Ethanol from a Retrofitted Dry Mill Corn Ethanol Plant

This study conducts a life cycle assessment of a simulated dry mill corn ethanol facility in California’s Central Valley retrofitted to also produce ethanol from corn stover, a cellulosic feedstock. The assessment examines three facility designs, all producing corn ethanol and wet distiller’s grains and solubles as a co-product: a baseline facility with no cellulosic retrofit, a facility retrofitted with a small capacity for stover feedstock, and a facility retrofitted for a large capacity of stover feedstock. Corn grain is supplied by rail from the Midwest, while stover is sourced from in-state farms and delivered by truck. Two stover feedstock supply scenarios are considered, testing harvest rates at 25 or 40 % of stover mass. Allocation is required to separate impacts attributable to co-products. Additional scenarios are explored to assess the effect of co-product allocation methods on life cycle assessment results for the two fuel products, corn ethanol and stover ethanol. The assessment tracks greenhouse gas (GHG) emissions, energy consumption, criteria air pollutants, and direct water consumption. The GHG intensity of corn ethanol produced from the three facility designs range between 61.3 and 68.9 g CO₂e/MJ, which includes 19.8 g CO₂e/MJ from indirect land use change for Midwestern corn grain. The GHG intensity of cellulosic ethanol varies from 44.1 to 109.2 g CO₂e/MJ, and 14.6 to 32.1 g CO₂e/MJ in the low and high stover capacity cases, respectively. Total energy input ranges between 0.60 and 0.71 MJ/MJ for corn ethanol and 0.13 to 2.29 MJ/MJ for stover ethanol. This variability is the result of the stover supply scenarios (a function of harvest rate) and co-product allocation decisions.     

Production, transportation and milling costs of sweet sorghum as a feedstock for centralized bioethanol production in the upper Midwest

Sweet sorghum has been identified as a possible ethanol feedstock because of its biomass yield and high concentration of readily fermentable sugars. It has found limited use, however, because of poor post-harvest storage characteristics and short harvest window in cooler climates. Previous research (Bennett, A.S., Anex, R.P., 2008. Farm-gate production costs of sweet sorghum as a bioethanol feedstock. Transactions of the ASABE 51(2), 603-613) indicates that fermentable carbohydrates (FC) can be produced at less expense from sweet sorghum than from corn grain. Previous research, however, did not include costs associated with off-farm transportation, storage, or capital costs associated with milling and energy recovery equipment that are required to provide FC suitable for biological conversion. This study includes these additional costs and reevaluates sweet sorghum as a biocommodity feedstock. A total of eight harvest-transport-processing options are modeled, including 4-row self-propelled and 2-row tractor-pulled forage harvesters, two different modes of in-field transport, fresh processing, on-farm ensilage and at-plant ensilage. Monte Carlo simulation and sensitivity analysis are used to account for system variability and compare scenarios. Transportation costs are found to be significant ranging from $33 to $71 Mg (-1) FC, with highest costs associated with at-plant ensilage scenarios. Economies of scale benefit larger milling equipment and boiler systems reducing FC costs by more than 50% when increasing annual plant capacity from 37.9 to 379 million liters. Ensiled storage of high moisture sweet sorghum in bunkers can lead to significant losses of FC (>20%) and result in systems with net FC costs well above those of corn-derived FC. Despite relatively high transport costs, seasonal, fresh processed sweet sorghum is found to produce FC at costs competitive with corn grain derived FC.     

Evaluation of possible decay and termite resistance of particleboard containing waste tire rubber

Particleboard specimens produced by adding waste tire rubber particles were assayed against white- and brown-rot fungi and termites in laboratory conditions. Particleboards were manufactured from a mixture of pine and poplar particles bonded with two different resins (melamine/urea formaldehyde [MUF] and polyisocyanate [PI]) by adding waste tire rubber particles at three different levels (10%/90%, 20%/80%, and 30%/70% by weight of waste tire rubber/wood). The particleboard specimens with waste tire rubber were not generally resistant against four fungi tested. Only MUF-containing specimens showed considerably better performance in decay resistance tests using the brown-rot fungus, Postia placenta; however, addition of waste tire rubber into those specimens did not provide resistance in comparison with control specimens without tire rubber. Formosan termites were also able to degrade particleboard specimens with waste tire rubber.     

Effect of stover fraction and storage method on glucose production during enzymatic hydrolysis

One avenue for overcoming the economic challenges associated with the production of ethanol from renewable resources is to reduce the cost of the biomass feedstock. The balance between storage costs and benefits depend on the storage method and composition changes of individual stover fractions. Corn stover from bales stored inside and outside of a barn was separated into an interior and exterior layer after approximately 10 months of storage. The cobs, stalks, and leaves and husks were separated, dried, and ground through a 2 mm screen. Stover, sodium acetate (buffer), cellulase, and deionized water were added to 125 ml flasks. The mixture was held at 50 degrees C in an incubator and samples taken for glucose determination. The average glucose concentration after 60 h of hydrolysis from cobs, leaves and husks, and stalks was 10.5, 9.6, and 3.1 g/l, respectively. Cobs, leaves, and husks produced over 300% more glucose than stalks. Storage outside of the barn decreased the glucose production from individual stover components between 4% and 8%. The effect of stover fraction type on glucose production was significant, while the storage treatment effect was not significant. Fractionation of corn stover may be a method to increase the value of corn stover as a feedstock for glucose production.     

Silage studies IX biochemical changes in microbe-free silage

Summary If the aseptic plant material is regarded as a substrate for preservative microbial activity, it may be said that both the nitrogen and carbohydrate components undergo changes due to the influence of native enzymes in the plant material. These changes may very well be reflected in the microbial activity in a silage.It is interesting to compare the findings of this investigation, which show that during the days immediately after ensilage practically no changes take place when no bacteria are present. In a non-sterile ensilage, on the other hand, it is during this early stage that the briskest bacterial activity takes place.The chances of, say, an acid-forming microbial process actually lowering the pH in order that preservation of the material may take place are directly counteracted by the action of native enzymes of the vegetable material. During the days immediately after ensilage, however, if other conditions are favourable, microbial activity may clearly determine the whole course of events, and may possibly even inactivate the processes of the plant material itself.As is evident from the experiments described above, the activities inherent in the ensiled material itself are of no mean proportions. Further study of the mutual relationship of the ensilage and the various microbial fractions is therefore particularly necessary in order to be able to understand a number of processes of fundamental importance in biological preservation of plant material.