Untreated Wood Chips Research Articles

Study on mechanical behavior of modified wood chips reinforced cementitious composites and reinforcing mechanism of wood chips from the perspective of energy

ABSTRACT In this study, the mechanical behavior of modified wood chips reinforced cementitious composites was tested and compared with the composites prepared by ordinary(untreated) wood chips and the control. The effect of wood chips content was also evaluated. Then the reinforcing mechanism of modified wood chips was discussed through force analysis, contact angle test and surface energy calculation. And the reasons for the change of contact angle and surface energy were explained by FT-IR and SEM. The results showed that the compressive strength of modified wood chips reinforced cementitious composites decreased, whereas the flexural strength, flexural toughness, toughness index, fracture energy, and ductility index increased significantly compared to the control. With the increase in wood chips content, the compressive strength gradually decreased, the flexural strength increased at first and then decreased, and flexural toughness, toughness index, fracture energy, and ductility index gradually increased. Further, all the mechanical properties of modified wood chips reinforced cementitious composites were superior to those of ordinary wood chips reinforced cementitious composites. The reinforcing mechanism of modified wood chips is mainly attributed to the energy storage and dissipation behavior, and the modification improves the interfacial compatibility between the wood chips and cement matrix. Also, the combined modification makes the wood chips hydrophobic.

Study on wood chips modification and its application in wood-cement composites

Wood-cement composites have the advantages of high flexural strength, toughness, and impact resistance. However, the components such as hemicellulose and lignin in the wood chips can inhibit cement hydration, and thus the interface bonding between wood chips and cement matrix is poor. In order to address these issues, alkali cooking (mass concentration is 2–8%) and silane coupling agent (mass concentration is 1–5%) were used in this study to modify wood chips, and the resulting compressive and flexural strengths of wood-cement composites prepared from different kinds of modified wood chips were evaluated. Further, the XRD, SEM, and FT -IR tests were carried out to characterize the modified wood chips and explore the mechanism of modified wood chips incorporated composites. The results showed that the alkali cooking agent could effectively remove amorphous components, such as hemicellulose and lignin, from wood chips, improve crystallinity and relative cellulose content, and increase the surface roughness of wood chips. The silane coupling agent could chemically bond with wood chips to improve the interfacial properties between wood chips and cement matrix. The flexural strength of the composites prepared with wood chips treated with 3% silane coupling agent and 4% alkali cooking agent was increased, which was 11.9% higher than that of the composites prepared from wood chips treated only with 4% alkali cooking agent, while it was 27.1% and 31.6% higher than the composites prepared with untreated wood chips and mortar without wood chips, respectively. Alkali cooking modification and silane coupling agent treatment of wood chips can effectively improve the mechanical properties of composite materials.

Xylanase pretreatment of mechanically destructured chips of Eucalyptus tereticornis and its effect on kraft pulping

Mechanical pulping of raw wood material is a highly energy intensive and pollution generating step in the papermaking process. This study focused on combined mechanical and xylanase treatment prior to the kraft pulping of E. tereticornis. A screened pulp yield of 49.1% (on oven-dry wood basis) with a Kappa number of 24.9 was obtained at the optimum cooking temperature of 160 °C without any pretreatment of the wood chips. After mechanical treatment (destructuring), a slightly higher screened pulp yield (49.4%) was obtained with a Kappa number of 24.2 at the cooking temperature of 145 °C with the same active alkali charge (15%). The optimum cooking temperature was further reduced to 140 °C for the destructured xylanase-treated wood chips. The xylanase treatment resulted in a 2% reduction in screened pulp yield due to hydrolysis of xylan. However, the Kappa number was reduced to 18.2 after xylanase pretreatment of the mechanically destructured wood chips. The combined pretreatment (destructured and xylanase treatment) of wood chips resulted in a reduction in cooking temperature by 20°C compared to untreated wood chips. Such a reduction in cooking temperature can effectively reduce steam consumption. The combined pretreatment improved the pulp brightness by 2.0 (ISO points) and physical strength properties, which included the tensile index, tear index, and burst index by 11.06%, 21.72%, and 21.79%, respectively, compared to the control.

Impact of thermally modified wood on mechanical properties of mortar

Abstract In this study, the impact of partially replacing sand with sustainable and renewable biomass such as ground wood chips on the mechanical properties of mortar is investigated. The effect of thermal treated biomass on strength properties is also studied. Compared to the mortar containing untreated ground wood chips, those containing highly or lightly torrefied ground wood chips were found to have higher flexural strength and compressive strength due to the enhanced bonding between the wood chips and paste matrix. Although all the tested mortars with ground wood chips have lower strength than the mortar without any wood chips, their flexural toughness and toughness indices were found to be comparable or higher than the controlled mortar, indicating better energy absorption capacity and post-peak behavior.

Household food-waste composting using a small-scale composter

Household food-waste composting is an attractive alternative for Brazilian waste management; however, there are few programs or studies regarding the implementation or management of this small-scale process. This study investigates the performance of food‑waste composting using a simple and small-scale domestic composter. Three composting trials were conducted using food waste and wood chips in 10 L plastic bins using different filling schemes. In the first trial, the composter was filled weekly over two months. In the second, the composter was filled once with a mixture of food waste and 100% of the used wood chips from the previous trial. In the last third trial, the composter was filled with food waste and wood chips (50% of wood chips used in the second trial and 50% of untreated wood chips). The physical chemical parameters of the compost were monitored and the total coliforms and E. coli were measured. In all trials, the temperature varied between 26.7°C and 46.2°C throughout the process. The reduction in wet mass was 58-69%, while the reduction in dry mass was 37-61%. The pH value, the contents of carbon and nitrogen and the C/N ratio were in accordance with the values recommended in norm 25 (July, 2009) adopted by Brazil's Agriculture Ministry. Only the compost from Trial 2, which had 1900 MPN g-1total solids, did not meet the E. coli standards; this was likely due to the fact that when the temperatures did not reach the thermophilic phase, the relatively long time the waste remains in the composter allows these pathogenic microorganisms to decay naturally.

Pretreatment of radiata pine using two white rot fungal strains Stereum hirsutum and Trametes versicolor

Stereum hirsutum and Trametes versicolor, were studied over a period of 3–7weeks for pretreatment of radiata pine wood chips. Chemical analysis of pretreated biomass showed that the two studied strains were able to selectively degrade lignin. Selective lignin degradation was greater in week 3 of the pretreatment by Trametes versicolor compared to the other strain. Lengthening pretreatment time increased both lignin and cellulose losses which caused a reduction in selective lignin degradation for both strains. X-ray diffractometry showed that after seven weeks of pretreatment, the crystallinity of the woody biomass was decreased significantly. It decreased from 46% for untreated wood chips to 37% and 44% for Stereum hirsutum and Trametes versicolor treated biomass, respectively. The pretreatment with these two white rot fungi showed that 3-week pretreatment provided a cellulose rich biomass with the minimum cellulose loss compared to the other time of pretreatment.

Effect of Treated Wood on Biosolids Composting

ABSTRACTThe possibility of using construction and demolition (C&D) waste wood as a bulking material in biosolids composting was investigated. Potential contaminants in C&D waste wood include arsenic (As), chromium (Cr), and copper (Cu) from treated wood, and lead (Pb) from paints. Untreated and treated woodchips from C&D wood were mixed with biosolids, composted using an aerated static pile process, and cured. There were no significant differences between untreated and treated woodchips with respect to composting process, time to stability, or product quality. Composting parameters monitored included moisture content, pH, electrical conductivity, organic matter degradation, fecal coliform levels, and stability by respirometry. Finished compost quality was evaluated in terms of potential toxic elements (PTE) levels. PTE values in treated woodchips (26 ± 35, 29 ± 41, 56 ± 46, and 5 ± 5 µg·g−1 for As, Cr, Cu, and Pb, respectively) were higher and more variable than those in the untreated woodchips (3 ± 3, 17 ± 8, 13 ± 2, and 0.5 ± 0.0 µg·g−1). However, both untreated and treated wood compost products met Canadian Council of Ministers of the Environment Category B values for PTE. In addition, and only molybdenum (Mo) and Cu exceeded Category A thresholds. Biosolids were the most significant contributor of Mo, while Cu contributions came from both biosolids and wood chips; some samples of pressure-treated wood showed concentrations of Cu in the range of 765 to 8,455 µg·g−1. The results of this study suggest that treated wood from C&D recycling facilities will not significantly degrade the quality of biosolids compost products.

Dominating High Temperature Corrosion Mechanisms in Low Alloy Steels in Wood Chips Fired Boilers

Ash related problems such as slagging, fouling, and high temperature corrosion in biomass fired boilers are still insufficiently explored due to the complexity of the underlying processes. High temperature corrosion of low alloy steels like 13CrMo4-5 has already been investigated in plants firing chemically untreated wood chips. In this earlier work it has been suggested that the oxidation of the steel is the dominating mechanism in the material temperature range between 450 and 550 °C. Unfortunately the exponential dependence of the material degradation on the flue gas temperature also found within this work cannot be explained with the proposed corrosion mechanism. To determine the dominating corrosion mechanism, additionally test runs have been carried out in a specially designed drop tube reactor. To investigate the time-dependent corrosion behavior of 13CrMo4-5, a newly developed mass loss probe was applied under several constant parameter setups. In addition to these measurements, the time-dependent oxidation of 13CrMo4-5 under air was investigated in a muffle furnace. To gain relevant information regarding the corrosion mechanism prevailing, the deposits as well as the corrosion products have been examined subsequently to the test runs by means of scanning electron microscopy and energy dispersive X-ray analyses. With the experimental data gained it could be shown that the dominating corrosion mechanism strongly depends on the conditions prevailing (e.g., steel temperature, flue gas temperature, and velocity) and can either be the oxidation of the steel by gaseous O2 and H2O or a combination of oxidation and active Cl-induced oxidation.

Causes and prevention of foot problems in Greater one‐horned rhinoceros Rhinoceros unicornis in zoological institutions

Greater one‐horned rhinoceros Rhinoceros unicornis have been successfully maintained by and bred at zoological gardens in the past half century. Despite this success, decades ago it was recognized that this species frequently develops foot lesions. Such damage can impair the health and well‐being of an individual, and contribute to a reduction of its lifespan. The death of a breeding bull or cow will have an effect upon the success of the breeding programme. Various studies have been carried out to determine the types and causes of foot problems in Greater one‐horned rhinoceros with the aim of identifying long‐term solutions to this health concern. The most effective method for preventing lesions and improving the health of the feet in rhinoceros is to utilize an appropriate substrate (e.g. 50 cm‐deep untreated wood chips) in both outdoor enclosures and indoor stables.

Short term online corrosion measurements in biomass fired boilers. Part 2: Investigation of the corrosion behavior of three selected superheater steels for two biomass fuels

The high temperature corrosion behavior of the boiler steels 13CrMo4-5 (1.7335), P91 (1.4903) and 1.4541 has been investigated during short-term test runs (~500h) at a biomass fired grate furnace combined with a drop tube. For the test runs performed with 13CrMo4-5 and P91 chemically untreated wood chips have been used as fuel, whereas waste wood has been used for test runs with P91 and 1.4541. Online corrosion probes and a mass loss probe have been used applying a methodology developed in a previous study to correct for a measurement error occurring during short-term measurements with online corrosion probes (mass loss correction). Furthermore, deposit probe measurements have been performed to evaluate the deposit build-up rate and the chemical composition of deposits. SEM/EDX analyses of the corrosion probes have been performed subsequently to the test runs to gain information regarding the chemical composition and structure of the deposits as well as the corrosion layers.The furnace has been operated at constant load to ensure constant combustion conditions. The flue gas temperature at the probes has been varied between 740 and 900°C and the probe surface temperature has been varied between 400 and 560°C in order to determine their influence on the corrosion rate.General trends determined by the variation of these temperatures were similar for all boiler steels: the corrosion rate increased with increasing flue gas temperature and also with increasing probe surface temperature. For chemically untreated wood chips combustion at low flue gas temperatures (740°C) the corrosion rates were comparable for 13CrMo4-5 and P91 at all probe surface temperatures. However, at flue gas temperatures of 800°C and higher P91 showed better corrosion resistance than 13CrMo4-5. For waste wood combustion 1.4541 generally showed a better corrosion resistance than P91.The mass loss correction of the measurement error occurring in the initial phase resulted in different errors of 55% for 13CrMo4-5 and 32% for P91 for chemically untreated wood chips. For waste wood the mass loss correction resulted in errors of 55% for P91 and 77% for 1.4541. The results from the mass loss determination for the waste wood test runs scattered stronger compared to the wood chips test runs. Therefore, the fits were not that accurate and the error margin was higher. However, the results outline that the mass loss correction is relevant in order to achieve a meaningful comparison of different short-term test runs using online corrosion probes.

Low-Temperature Corrosion in Biomass Boilers Fired with Chemically Untreated Wood Chips and Bark

Low-temperature corrosion often causes failures of cold-end parts (economizers, air pre-heaters, and fire tubes of hot water boilers) in biomass boilers firing chemically untreated wood chips and bark. The most relevant mechanisms causing low-temperature corrosion are condensation of acids and hygroscopic salts in the deposits on heat-exchanger surfaces. This article offers a short review on acid condensation and presents a detailed study on the formation of hygroscopic salts, which may absorb moisture from the flue gas to such an extent that they are dissolved and form highly concentrated salt solutions. Typical fuel compositions of wood chips and bark in combination with typical operating conditions of biomass grate furnaces have been used to estimate the compositions of ash deposits on heat-exchangers. Based on these compositions, thermodynamic equilibrium calculations have been conducted in the range of 70–400 °C, which have revealed that the hygroscopic salts K2ZnCl4, KCaCl3, and CaCl2 can be formed ...

Integration of Shiitake cultivation and solid-state anaerobic digestion for utilization of woody biomass

Pretreatment technologies that can not only reduce the recalcitrance of woody biomass but also achieve a high benefit-cost ratio are desirable for bioenergy production from woody biomass. In this study, an integrated process was proposed and conducted by pretreating woodchips via Shiitake cultivation for improved methane yield during solid-state anaerobic digestion (SS-AD), and simultaneously producing mushrooms as a high-value co-product. Shiitake cultivation using woodchips as the main substrate ingredient obtained mushroom yields comparable to those using a commercial substrate. Enzymatic digestibility and cumulative methane yields (133–160Lkg−1VS during 62days of SS-AD) of pretreated substrates (spent mushroom substrate) were at least 1.5times as high as those of untreated woodchips. Compared to a sole SS-AD process, the integrated Shiitake cultivation/SS-AD process increased methane production and solid waste reduction per kilogram of woodchips by about 1.5 and 8times, respectively.

Enhanced ethanol and biogas production from pinewood by NMMO pretreatment and detailed biomass analysis.

N-Methyl morpholine-N-oxide (NMMO) is an environmentally friendly and commercially applied cellulose solvent that is suggested for pretreatment of lignocelluloses to improve biofuel productions. However, the underlying mechanisms of the improvements have been poorly understood yet. In an attempt to investigate the mechanisms, pinewood powder and chips were pretreated with 85% (w/w) NMMO at 120°C for 1–15 h. The pretreatment improved ethanol production yield from 7.2% (g/g) for the untreated wood powder to 68.1–86.1% (g/g) and from 1.7% (g/g) for the untreated wood chips to 12.6–51.2% (g/g) of theoretical yield. Similarly, the biogas yields of untreated wood chips and powder were improved from 21 and 66 (mL/g volatile solids) by 3.5–6.8- and 2.6–3.4-folds, respectively. SEM micrographs indicated major increase in the wood porosity by the pretreatment, which would confirm increase in the water swelling capacity as well as enzyme adsorption. The analysis of X-ray diffraction showed considerable reduction in the cellulose crystallinity by the pretreatment, while FTIR spectroscopy results indicated reduction of lignin on the wood surface by the pretreatment.

Assessment of Online Corrosion Measurements in Combination with Fuel Analyses and Aerosol and Deposit Measurements in a Biomass Combined Heat and Power Plant

To systematically investigate high-temperature corrosion of superheaters in biomass combined heat and power (CHP) plants, a long-term test run (5 months) with online corrosion probes was performed in an Austrian CHP plant (28 MWNCV; steam parameters: 32 t/h at 480 °C and 63 bar) firing chemically untreated wood chips. Two corrosion probes were applied in parallel in the radiative section of the boiler at average flue gas temperatures of 880 and 780 °C using the steel 13CrMo4-5 for the measurements. Corrosion rates were determined for surface temperatures between 400 and 560 °C. The results show generally moderate corrosion rates and a clear dependence upon the flue gas temperatures and the surface temperatures of the corrosion probes, but no influence of the flue gas velocity has been observed. The data are to be used to create corrosion diagrams to determine maximum steam temperatures for superheaters in future plants, which are justifiable regarding the corrosion rate. Dedicated measurements were performed at the plant during the long-term corrosion probe test run to gain insight into the chemical environment of the corrosion probes. From fuel analyses, the molar 2S/Cl ratio was calculated with an average of 6.0, which indicates a low risk for high-temperature corrosion. Chemical analyses of aerosols sampled at the positions of the corrosion probes showed that no chlorine is present in condensed form at the positions investigated. Deposit probe measurements performed at the same positions and analyses of the deposits also showed only small amounts of chlorine in the deposits, mainly found at the leeward position of the probes. Subsequent to the test run, the corrosion probes have been investigated by means of scanning electron microscopy/energy-dispersive X-ray spectroscopy analyses. The results confirmed the deposit probe measurements and showed only minor Cl concentrations in the deposits and no Cl at the corrosion front. Because, in the case of Cl-catalyzed active oxidation, a layer of Cl is known to be found at the corrosion front, this mechanism is assumed to be not of relevance in the case at hand. Instead, elevated S concentrations were detected at the corrosion front, but the corrosion mechanism has not yet been clarified.

Kraft pulping and ECF bleaching of Eucalyptus globulus pretreated by the white-rot fungus Ceriporiopsis subvermispora

Eucalyptus globulus wood chips were decayed by the lignin-degrading fungus Ceriporiopsis subvermispora as a pretreatment step before kraft pulping. Weight and component losses of wood after the biotreatment were the following: weight (5%), glucans (1.5%), xylans (4.3%), lignin (5.7%) and extractives (57.5%). The residual amount of lignin (expressed by the kappa number) in pulps from biotreated wood chips was lower than that of pulps from the undecayed control. Depending on the delignification degree, kraft biopulps presented similar or up to 4% increase in pulp yield and 20% less hexenuronic acids (HexA) than control pulps. The extended delignification with O2 decreases approximately 50% of the kappa number of the pulps and increases brightness, but had no effect in HexA reduction. The bleaching steps with chlorine dioxide (D0ED1 sequence) decreased the kappa number up to 97%, increased pulp brightness up to 84% ISO and decreased HexA amount up to 91%. The use of C. subvermispora in biopulping of E. globulus generated important benefits during the production of kraft pulps that are reflected in a high pulp yield, low residual lignin content, low HexA amount, high brightness and viscosity of the biopulps as compared with pulps produced from untreated wood chips.

Extraction of xylans from hardwood chips prior to kraft cooking

The aim of this work is to define an extraction process of hemicelluloses from hardwood chips, prior to their transformation into paper pulp by the kraft process. Eucalyptus wood chips were submitted to autohydrolysis and acid hydrolysis treatments. Autohydrolysis means that no extra acid is added during the heating of the wood suspension, whereas sulphuric acid is added for the acid hydrolysis treatment. The liquor to wood ratio was 4, and temperature and time were varied so as to optimise the hemicelluloses extraction. Quantities of xylans varying between 12 and 38g/l of hydrolysate (or between 9 and 15% on wood) could be extracted.Kraft cooking process was applied to the pre-hydrolysed wood chips. It was shown that they were easier to delignify than untreated wood chips, and the resulting pulp was also easier to bleach. The resulting cellulosic fibres were characterised for their papermaking properties: the higher the pentosan removal, the lower the strength properties of the pulps produced.

The effect of pre-softened wood chips on wood fibre aspect ratio and mechanical properties of wood–polymer composites

The objective of this work was to study the effect of chemical pre-treatment and moisture content of wood chips on the wood particle aspect ratio after compounding in a twin-screw extruder and on the mechanical properties of wood–polymer composites (WPCs). Composites with 50 wt.% wood content were manufactured using pre-treated and untreated wood chips. The effect of wood moisture content on composite properties was studied by using dried and undried wood chips. The mechanical properties and fracture surfaces of the composites as well as the microstructure and aspect ratio of wood particles after compounding were studied. The highest wood particle aspect ratio after extrusion was achieved by using pre-treated, undried wood chips as raw material. The chemical pre-treatment was found to enhance the defibration of wood chips as well as the mechanical properties of the composites.

Alkaline-sulfite chemithermomechanical pulping of Eucalyptus grandis biotreated by Ceriporiopsis subvermispora under varied culture conditions

Abstract The effect of different culture conditions have been evaluated concerning the extracellular enzyme activities of the white-rot fungus Ceriporiopsis subvermispora growing on Eucalyptus grandis wood. The consequence of the varied fungal pretreatment on a subsequent chemithermomechanical pulping (CTMP) was addressed. In all cultures, manganese peroxidase (MnP) and xylanase were the predominant extracellular enzymes. The biopulping efficiency was evaluated based on the amount of fiber bundles obtained after the first fiberizing step and the fibrillation levels of refined pulps. It was found that the MnP levels in the cultures correlated positively with the biopulping benefits. On the other hand, xylanase and total oxalate levels did not vary significantly. Accordingly, it was not possible to determine whether MnP accomplishes the effect alone or depends on synergic action of other extracellular agents. Pulp strength and fiber size distribution were also evaluated. The average fiber length of CTMP pulps prepared from untreated wood chips was 623 μm. Analogous values were observed for most of the biopulps; however, significant amounts of shorter fibers were found in the biopulp prepared from wood chips biotreated in cultures supplemented with glucose plus corn-steep liquor. Despite evidence of reduced average fiber length, biopulps prepared from these wood chips presented the highest improvement in tensile indexes (+28% at 23° Schopper-Riegler).

Quaternized wood as sorbent for hexavalent chromium.

The potential of quaternized wood (QW) chips in removing hexavalent chromium from synthetic solution and chrome waste under both batch and continuous-flow conditions was investigated. Sorption was found to be dependent on pH, metal concentration, and temperature. QW chips provide higher sorption capacity and wider pH range compared with untreated wood chips. The equilibrium data could be fitted into the Langmuir isotherm model, and maximum sorption capacities were calculated to be 27.03 and 25.77 mg/g in synthetic chromate solution and chrome waste, respectively. The presence of sulfate in high concentration appeared to suppress the uptake of chromium by QW chips. Column studies showed that bed depth influenced the breakthrough time greatly whereas flow rate of influent had little effect on its sorption on the column.

Effects of Different Microorganisms on Pulp and Paper Properties

Abstract Pretreatment of wood chips with some microorganisms including white-rot fungi and streptomyces improves the strength properties of mechanical pulps. We studied the effect of these white-rot fungi and streptomyces on the mechanical properties of handsheets. Strength and optical properties were compared in handsheets prepared from mechanical pulp of treated and untreated wood chips. The fungal pretreatments resulted in handsheet strength properties better than the control and also better than streptomyces when compared at an equivalent freeness. Fungal pretreatments decreased brightness and light-scattering coefficients but did not adversely affect opacity. Lignin content of the chips was reduced by fungal pretreatments.