Non-treated Straw Research Articles

Environmentally sound materials from rice straw for elevator decoration

The main goal of this work was to use rice straw (WS) in the production of environmentally sound materials using corn based adhesives (CA). Treatments of WS with NaOH and hot-water were undertaken to evaluate the effect of such treatments on the performance of produced materials. The influence of material density, starch content and varieties of starch (cornstarch, cassava starch, potato starch) on properties of materials was also investigated. Results showed that cornstarch based materials had higher flexural properties. Materials made from hot-water treated straw and cornstarch had better interface and higher flexural properties, and flexural strength and flexural elastic modulus reached peak values at starch content of 10% and material density of 0.7 g/cm3. Materials made from non-treated straw and cornstarch had lower moisture absorption. Moisture absorption was increasing with starch content increasing and density decreasing. The materials developed from this work may have potential application for ceiling panels and bulletin boards.

Liquid hot water pretreatment to enhance the anaerobic digestion of wheat straw—effects of temperature and retention time

Wheat straw is an abundant agricultural waste that is rich in lignocellulose. However, its waxy surface, highly crystallized structure, and limited surface area make it difficult to be hydrolyzed and used efficiently by microorganisms. Liquid hot water (LHW) pretreatment was studied to explore the feasibility of improving the methane yield of wheat straw in anaerobic digestion (AD). The results showed that the crosslinking structure of wheat straw was broken by LHW pretreatment. Some pores and cracks appeared on the surface of the pretreated wheat straw, increasing the microbial attachment sites. Under different hydrothermal temperatures (150-225 °C) and retention times (5-60 min), the degradation of hemicellulose ranged from 27.69 to 99.07%. The maximum methane yield (201.81 mL CH4/g volatile solids) was achieved after LHW pretreatment at 175 °C for 30 min, which was a 62.9% increase compared with non-treated straw. LHW at high temperatures such as 225 °C was not suitable for the AD of wheat straw. Methane yield results were fitted with the first-order and modified Gompertz equations to evaluate the hydrolysis rate and inhibitory effects of the pretreated materials in AD.

Mechanical Pretreatment in a Screw Press Affecting Chemical Pulping of Lignocellulosic Biomass

To convert lignocellulose into transportation fuels and chemical products, pretreatment of the biomass, leading to the separation of the main components (cellulose, hemicellulose, and lignin), is a crucial and still challenging first step. Within this study, the screw press pretreatment of lignocellulosic biomass and its effect on the subsequent chemical pretreatment steps were evaluated. Macroscopic disruption and defibration of reed straw after screw press pretreatment were confirmed by scanning electronic microscopy and dye adsorption studies, showing an enhancement of the accessible surface area. Alkaline and dilute acid hydrolysis was tested to study the release of phenols or sugars from screw-press-treated and non-treated straw materials. To showcase a realistic subsequent chemical pretreatment step, kinetics of enzymatic hydrolysis after a biogenic and biphasic fractionation (OrganoCat) process was tested to evaluate the release of glucose from cut and pressed reed straw. Pretreatment by a screw pr...

Biomethane potential of wheat straw: Influence of particle size, water impregnation and thermal hydrolysis

The anaerobic digestion of organic wastes such as wheat straw represents a very interesting means of generating biogas while reducing the amount of waste to disposal. An enhancement in the hydrolysis limited digestion of straw can be achieved by optimizing operation and performing pre-treatments. In this study, the influence of particle size, water impregnation and thermal pre-treatment was investigated through biochemical methane potential tests (BMP). The maximum methane yield was obtained by heating the straw at 200°C for 5min followed by steam explosion, obtaining a 27% increase in methane productivity compared to non-treated straw (from 233 to 296mL CH4/gVSfed). Cutting (3–5cm) showed to be better than milling (<1mm), and the impregnation of the straw with water helped to enhance BMP test results by 4–10% (supposed better mixing due to a 10 times reduction of solids concentration) but had no effect on thermal pre-treatment. On the contrary, the economic impact of milling and water addition on a thermal pre-treatment would be absolutely negative, increasing the operation cost necessary to reduce the size and to heat water, respectively.

Effect of Pretreatment of Raw Material on Properties of Particleboard Panels Made from Wheat Straw

The objective of this study was to evaluate properties of experimental particleboard panels manufactured from wheat straw that had been pretreated with acetic anhydride, soapy solution, hot water, or steam. Wheat straw particles were mixed with commercially manufactured wood particles at a ratio of 60%. Control straw particleboards with non-treated straw and wood particles were also produced. The results showed that the pretreatment of wheat straw significantly improved both the physical and mechanical properties of the straw particleboards. Panels made from wheat straw treated with a 9% solution of acetic anhydride or boiled in a soapy solution resulted in the highest mechanical properties, with an increase in bending strength values. Regarding internal bond strength, the samples made from wheat straw particles treated with acetic anhydride and a soapy solution had 2 and 3 times higher values, respectively, than those of non-treated samples. It seems that the pretreatment of wheat straw had a greater effect on the thickness swelling of the specimens than on their water absorption.

Influence of thermal pretreatment on the biochemical methane potential of wheat straw

The biochemical methane potential of steam exploded wheat straw was evaluated in a pilot plant under different temperature-time combinations. The optimum was obtained for 1 min and 220 °C thermal pretreatment (3.5 severity factor), resulting in a 20% increase in methane production respect non-treated straw. For more severe treatments the biodegradability decreased due to a possible formation of inhibitory compounds. The results of the tests were modeled with a first order equation to estimate the hydrolysis constant and biodegradability extent, and the influence of temperature and time on the kinetic parameters was obtained with a response surface study. The data processing confirmed the accuracy of the model and the optimum operation conditions, and demonstrated that the biomethanization of raw and pretreated wheat straw is limited by the hydrolysis, being the individual influence of temperature and time much more important than the interaction between them.

Rice Straw and Cornstarch Biodegradable Composites

The main goal of this work was to use rice straw (RS) in the production of environmentally sound composites using corn based adhesives (CA). Treatments of RS with NaOH and hot-water were undertaken to evaluate the effect of such treatments on the performance of produced composites. The influence of composite density and starch content on properties of composites was also investigated. The microstructure of fractured surfaces was further observed. Results showed that cornstarch based composites had higher flexural strength. Composites made from hot-water treated straw and cornstarch had better interface and higher flexural strength, and flexural strength reached peak values at starch content of 10% and composite density of 0.7 g/cm3. Composites made from non-treated straw and cornstarch had lower moisture absorption. Moisture absorption was increasing with starch content increasing and density decreasing. The composites developed from this work may have potential application for ceiling panels and bulletin boards.

Grinding performance and physical properties of non-treated and steam exploded barley, canola, oat and wheat straw

Grinding experiments were conducted on non-treated and steam exploded barley, canola, oat and wheat straw using a forage chopper and a hammer mill (screen sizes of 30, 6.4, 3.2 and 1.6 mm) to determine specific energy requirements, and geometric mean particle size and distribution of ground material. The bulk density of non-treated biomass was significantly higher than bulk density of steam exploded agricultural biomass. For non-treated agricultural straw, the particle density of canola and oat straw significantly increased with a decrease in hammer mill screen size from 30 to 1.6 mm. The particle density of steam exploded barley and oat straw was significantly higher than non-treated straw, except for barley at 6.4 mm hammer mill screen size. The particle density of steam exploded canola straw was not statistically different from non-treated straw. The chopper consumed highest (3.15 ± 0.09 kWh t−1) and lowest (1.96 ± 0.33 kWh t−1) specific energy to chop barley and canola straw, respectively. The highest and lowest specific energy was consumed by wheat (42.57 ± 2.04 kWh t−1) at 1.6 mm and canola (1.46 ± 0.30 kWh t−1) straws ground using 30 mm hammer mill screen size, respectively. For steam exploded agricultural biomass, the highest and lowest specific energy was consumed by oat (33.18 ± 3.10 kWh t−1) at 1.6 mm and canola (2.69 ± 0.26 kWh t−1) straws ground using 6.4 mm hammer mill screen size, respectively. Specific energy required by hammer mill to grind non-treated and steam exploded barley, canola, oat and wheat straw showed a negative power correlation with hammer mill screen sizes.

Pelleting characteristics of selected biomass with and without steam explosion pretreatment

Processing and densification of agricultural biomass into high density and durable pellets are critical to facilitate handling, storage and transportation. Biomass pelleting experiments were designed to conduct single and pilot scale pelleting of non-treated and steam exploded barley, canola, oat and wheat straw grinds acquir ed from 6.4, 3.2, 1.6 and 0.8 mm hammer mill screen sizes at 10% moisture content (wb). Single-pelleting was performed by applying compression pressures of 31.6, 63.2, 94.7, and 138.9 MPa using a close-fit plunger die assembly (die length 135.3 mm and diameter of ( 6.30±0.5 ) mm). During pilot scale pelleting, customization of ground straw material was performed by adding steam exploded biomass in increments of 25% to non-treated ground straw for respective biomass at specific grind size. Ground s traw samples were conditioned to 17.5% moisture content and 10% flaxseed oil was added to increase the bulk density and flowability of grinds, which resulted in the production of pellets. The quality of pellets from single pelleting experiments was ascertained by measuring their respective density and durability. In addition, the change in pellet density was measured after a storage period of one month to determine its dimensional stability. It was determined that applied pressure and pre-treatment were significant factors affecting the pellet density. Also, bigger grind sizes and lower applied pressures resulted in higher pellet relaxations (lower pellet densities) during storage of pellets. The pilot scale pellet mill produced pellets from ground non-treated straw at hammer mill screen sizes of 0.8 and 1.6 mm and customized samples having 25% steam exploded straw at 0.8 mm. It was observed that the p ellet bulk density and particle density are positively correlated. The density and durability of agricultural straw pellets significantly increased with decrease in hammer mill screen size from 1.6 mm to 0.8 mm. Customization of agricultural straw by adding 25% of steam exploded straw by weight is possible, but it did not improve pellet quality. In addition, d urability of pellets was negatively correlated to pellet mill throughput and was positively correlated to specific energy consumption. Keywords: b iofuel s , b iomass, d ensity, d urability, p elleting, s pecific e nergy, s team e xplosion, p retreatment DOI: 10.3965/j.issn.1934-6344.20 1 0.0 3 .0 62 -0 79 Citation: Phani Adapa, Lope Tabil, Greg Schoenau , Anthony Opoku . Pelleting c haracteristics of s elected b iomass with and without s team e xplosion p retreatment. Int J Agric & Biol Eng, 20 1 0; 3 ( 3 ): 62 <span style=font-size: 9pt; line-height: 130%; font-family:

Physical and frictional properties of non-treated and steam exploded barley, canola, oat and wheat straw grinds

During storage and handling, accurate knowledge of the physical and frictional behaviors of biomass grinds is essential for the efficient design of equipment. Therefore, experiments were performed on non-treated and steam exploded barley, canola, oat and wheat straw grinds to determine their coefficient of internal friction and cohesion at three hammer mill screen sizes of 6.4, 3.2 and 1.6 mm, three normal stress values of 9.8, 19.6 and 39.2 kPa at 10% moisture content (wb). At any specific hammer mill screen size, the geometric mean particle size and bulk density of non-treated straw was significantly larger than steam exploded straw. The bulk density of ground straw significantly increased with a decrease in hammer mill screen sizes. The steam exploded straw grinds resulted in higher coefficient of internal friction compared to non-treated straw grinds primarily because of lower bulk densities. The coefficient of friction for non-treated barley, canola, oat and wheat straw were in the range of 0.505 to 0.584, 0.661 to 0.665, 0.498 to 0.590, and 0.532 to 0.591, respectively. Similarly, the coefficient of friction for steam exploded barley, canola, oat and wheat straw were in the range of 0.562 to 0.738, 0.708 to 0.841, 0.660 to 0.860, and 0.616 to 1.036, respectively, which were higher than non-treated straw of the kind. Power, logarithmic or exponential equations were developed to predict the coefficient of internal friction and cohesion with respect to average geometric mean particle sizes for non-treated and steam explode barley, canola, oat and wheat straw grinds.

Compression Characteristics of Non-Treated and Steam-exploded Barley, Canola, Oat, and Wheat Straw Grinds

Compaction of low bulk density agricultural biomass is a critical and desirable operation for sustainable and economic availability of feedstock for biofuel industry.A comprehensive study of the compression characteristics (density of pellet and total specific energy required for compression) of ground non-treated and steam-exploded barley, canola, oat, and wheat straw obtained from three hammer mill screen sizes of 6.4, 3.2 and 1.6 mm at 10% moisture content (wb) was conducted. Four preset pressures of 31.6, 63.2, 94.7, and 138.9 MPa were applied using an Instron testing machine to compress samples in a cylindrical die. Ground steam-exploded barley straw at screen sizes of either 3.2 or 1.6 mm produced high density compacts, while ground steam-exploded canola, oat, and wheat straw at screen sizes of 6.4, 3.2 or 1.6 mm produced high density compacts. Steam-exploded barley straw for 3.2 mm at 138.9 MPa produced compacts having 13% higher density and consumed 19% lower total specific energy compared to non-treated straw. Steam-exploded canola straw for 1.6 mm at 138.9 MPa produced compacts having 13% higher density and consumed 22% higher total specific energy compared to non-treated straw. Steam-exploded oat straw for 3.2 mm at 94.7 MPa produced compacts having 19% higher density and consumed 13% higher total specific energy compared to non-treated straw. Steam-exploded wheat straw for 6.4 mm at 138.9 MPa produced compacts having 17% higher density and consumed 17% higher total specific energy compared to non-treated straw. Three compression models, namely: Jones model, Cooper-Eaton model, and Kawakita-Ludde model were considered to determine the pressure-volume and pressure-density relationship of non-treated and steam-exploded straws. Kawakita-Ludde model provided the best fit to the experimental data having R2 values of 0.99 for non-treated straw and 1.00 for steam-exploded biomass samples. The steam-exploded straw had higher porosity than non-treated straw. In addition, the steam-exploded straw was easier to compress since it had lower yield strength or failure stress values compared to non-treated straw.

Effect of enzyme extracts isolated from white-rot fungi on chemical composition and in vitro digestibility of wheat straw

A series of in vitro experiments were completed to evaluate the potential of enzyme extracts, obtained from the white-rot fungi Trametes versicolor (TV1, TV2), Bjerkandera adusta (BA) and Fomes fomentarius (FF), to increase degradation of cell wall components of wheat straw. The studies were conducted as a completely randomized design and analysed using one-way ANOVA. Enzyme activities of the extracts, previously obtained from a liquid culture medium, were characterized in terms of laccase and peroxidase for ligninolytic activity. Carboxymethyl cellulase (CMCase) and avicell digesting cellulase (Avicelase) were used for cellulolytic enzyme assays. Wheat straw samples were incubated with enzyme extracts in a citrate buffer (pH 5.0) in a forced air oven at 25 °C for 6 days. In vitro NDF digestibility (IVNDFD), and the rate and extent of NDF fermentation, without and after incubation with the white-rot enzyme extracts, were determined using a gravimetric microbiological method and a gas production technique, respectively. Results from cell wall chemical composition showed that TV2 and BA enzyme extracts decreased NDF concentration (P<0.05) and that TV1 had higher activity (P<0.05) towards cellulose. There was an increase in IVNDFD (P<0.05), resulting from treatment of wheat straw with enzyme extracts from BA, TV1 and TV2, reaching a difference of 13% for TV2 (P<0.05), versus the non-treated straw control. Treatment with enzyme extract from TV2 caused increased gas production (P<0.05) after the first 20 h of incubation, and also increased the maximum rate of gas production, thus enhancing fermentation kinetics. This study indicates that enzyme extracts from white-rot fungi can be used to develop new approaches to overcome low digestibility of some plant cell walls. Utilization of different substrates to produce enzyme extracts can lead to production of viable ligninolytic complexes which could improve the nutritive value of fibrous feeds.

Microbial community structure and activity in wheat straw after inoculation with biological control organisms

Wheat straw on pans of soil in a greenhouse was inoculated with either the fungus Limonomyces roseipellis or the bacterium Pseudomonas fluorescens strain Pf-5, biocontrol agents for Pyrenophora tritici-repentis, a straw-borne phytopathogen. The inoculated straw was exposed to alternate wetting and drying for 7 weeks to assess the effects of intentionally applied microorganisms on selected ecological parameters of the plant litter microflora. Pseudomonas fluorescens had little effect, but L. roseipellis had measurable effects on some aspects of microbial community structure and function. The frequency distribution of fungal taxa on straw was altered by L. roseipellis, with a large increase in yeasts and a decrease in several filamentous fungi. Compared with non-treated straw, respiration (CO 2 evolution) under conditions of adequate moisture (−0.1 MPa) was increased in straw colonized by L. roseipellis, but respiration at −7 MPa was unaffected. The spectrum of sole carbon sources utilized by the straw microflora was altered slightly in Limonomyces-treated straw. These observations provide a basis for further studies concerning inoculant-induced ecological effects under field conditions.

Kinetics of primary biodegradation of sulphosuccinate esters by Comamonas terrigena

A series of in vitro experiments were completed to evaluate the potential of enzyme extracts, obtained from the white-rot fungi Trametes versicolor (TV1, TV2), Bjerkandera adusta (BA) and Fomes fomentarius (FF), to increase degradation of cell wall components of wheat straw. The studies were conducted as a completely randomized design and analysed using one-way ANOVA. Enzyme activities of the extracts, previously obtained from a liquid culture medium, were characterized in terms of laccase and peroxidase for ligninolytic activity. Carboxymethyl cellulase (CMCase) and avicell digesting cellulase (Avicelase) were used for cellulolytic enzyme assays. Wheat straw samples were incubated with enzyme extracts in a citrate buffer (pH 5.0) in a forced air oven at 25 °C for 6 days. In vitro NDF digestibility (IVNDFD), and the rate and extent of NDF fermentation, without and after incubation with the white-rot enzyme extracts, were determined using a gravimetric microbiological method and a gas production technique, respectively. Results from cell wall chemical composition showed that TV2 and BA enzyme extracts decreased NDF concentration (P<0.05) and that TV1 had higher activity (P<0.05) towards cellulose. There was an increase in IVNDFD (P<0.05), resulting from treatment of wheat straw with enzyme extracts from BA, TV1 and TV2, reaching a difference of 13% for TV2 (P<0.05), versus the non-treated straw control. Treatment with enzyme extract from TV2 caused increased gas production (P<0.05) after the first 20 h of incubation, and also increased the maximum rate of gas production, thus enhancing fermentation kinetics. This study indicates that enzyme extracts from white-rot fungi can be used to develop new approaches to overcome low digestibility of some plant cell walls. Utilization of different substrates to produce enzyme extracts can lead to production of viable ligninolytic complexes which could improve the nutritive value of fibrous feeds.

Establishment of microbial inocula on decomposing wheat straw in soil of different water contents

The effects of five different microbial inoculant treatments on straw decomposition and its residual N content were determined in a wet (< −0.1 MPa water potential) and dry (approx. −1.4 MPa) silt loam soil. The inoculant treatments consisted of the cellulolytic fungi Trichoderma harzianum, Gliocladium roseum and Penicillium hordei added individually, and two mixtures, one containing T. harzianum and P. hordei, the other T. harzianum and the bacteria Closlridium butyricum and Enterobacter cloacae. In general, whereas all inoculants successfully established to different extents on the straw, none markedly improved decomposition in either wet or dry soil when compared with non-treated straw. After 6 months 50% dry matter loss had occurred in the wet soil while only about half of this had occurred in the dry soil. There was no difference in N content (mg N g −1 original straw) between straw treated with any microbial inoculant and controls, but the N gain to straw was significantly greater in the wet than in the dry soil. The failure to respond to inoculation could in part be due to the high natural C. butyricum populations present on the straw used. G. roseum and T. harzianum inocula were always present on at least 89% of straw pieces in wet soil but progressively decreased in the dry soil during the 28 wk experiment. Co-inoculation of T. harzianum and P. hordei resulted in the former being dominant in wet soil and the latter in the dry soil.

Decomposition of wheat and barley straw treated with urea-sulfuric acid

Wheat straw treated with 0.5 or 1.0 ml/g urea-sulfuric acid (1:1 acid in water v/v) and incubated in Protneuf or Woodburn silt loam soils in the laboratory decomposed faster than nontreated straw the first 4–6 weeks but at 12 weeks the nontreated straw had decomposed 25%–45% more. In a field experiment, urea-sulfuric acid treated straw, removed at 40-day intervals over 160 days, decomposed faster than nontreated straw. The differences were attributed to salt buildup in the laboratory samples, where electrical conductivities up to 17.6 dS/m were observed. In the field, leaching removed the excess salts. Nitrification produced up to 1875 mg NO 3 − N/kg Portneuf silt loam soil in the laboratory, indicating that nitrifying bacteria were not suppressed by the salt. Total plate counts with no straw were 1.8 × 106 microorganisms/g and with urea-sulfuric acid treated straw were 15.7 × 106/g soil after 14 days incubation. The respective actinomycete counts were 0.3 × 106 and 6.7 × 106/g for the no straw and straw-treated soils, respectively. The urea-sulfuric acid treatments suppressed straw decomposition in the laboratory and accelerated straw decomposition in the field.