Comparison of gasification and pyrolysis of thermal pre-treated wood board waste

The second step of a two-step process of thermo-chemical conversion of wood board waste is discussed in this paper. GC-TCD and FTIR analyses of the gas product enable to compare the two proposed way: pyrolysis and gasification of the pre-treated and virgin wood board sample between 800 and 1000 °C. The effect of the first step of the process (low-temperature pyrolysis which aims to remove nitrogen initially present in wood board waste) has shown to be really efficient as the production of ammonia observed during the second step decreases by a factor 6–8 jointly to a slight decrease of the energy recovery. The first step also prevents the production of hydrogen cyanide and is therefore essential. Concerning pre-treated samples, the best results have been obtained at 1000 °C with samples pre-treated at 250 °C. The way of gasification has been shown to be more efficient in term of energy recovery but leads to a production of ammonia larger than in the case of the pyrolysis way. The conversion of the pyrolysis residual char into an activated char must be considered since it presents a potential economic interest.     

Determination of airborne wood dust in Button samples by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS)

Emerging concerns regarding the toxicity of inhaled wood dust support the need for techniques to quantitate wood content of mixed industrial dusts. The diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis technique was applied to the determination of wood content of 181 inhalable dust samples (geometric mean concentration: 0.895?mg/m³; geometric standard deviation: 2.73) collected from six wood product industry factories using 25?mm glass fibre filters with the Button aerosol sampler. Prior to direct DRIFTS analysis the filter samples were treated with ethyl acetate and re-deposited uniformly. Standards ranging from 125?µg to 4000?µg were prepared for red oak, southern yellow pine, and red cedar and used for quantitation of samples depending upon the wood materials present at a given factory. The oak standards spectra were quantitated by linear regression of response in Kubelka-Munk units at 1736?cm^?1, whereas the pine standards and the cedar standards spectra were quantitated by polynomial regression of response in log 1/R units at 1734?cm^?1, with the selected wavenumbers corresponding to stretching vibration of free C=O from cellulose and hemicelluloses. For one factory which used both soft- and hard-woods, a separate polynomial standard curve was created by proportionally combining the oak and pine standards polynomial regression equations based on response (log 1/R) at 1734?cm^?1. The analytical limits of detection were approximately 52?µg of oak, 20?µg of pine, 30?µg of cedar, and 16?µg of mixed oak and pine for the factory with mixed woods. Overall, the average of dry wood dust percentage of inhalable dust was approximately 56% and the average dry wood dust weight was 0.572?mg for the Button samples. Across factories, there were statistically significant differences (p?<?0.001) for the percentage of dry wood dust in inhalable dust with factory averages ranging from 33.5 to 97.6%.     

Surface characterization of untreated and hydro‐thermally pre‐treated Turkey oak woods after UV‐C irradiation

The aim of this study was to determine the effect of UV‐C irradiation on the Turkey oak wood surface (Quercus cerris L.). In order to compare the effect of irradiation, both untreated wood samples and those treated with steam and heat were analyzed. The steam treatments were carried out in an autoclave at 130 °C; samples were then heated in an oven for 2 h at 180 °C. The physical and chemical changes brought about in the untreated and treated wood samples by the UV‐C light were monitored by colorimetry (color changes), X‐ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) (chemical composition) and scanning electron microscopy (SEM) (microstructure and morphology). A detailed analysis of the results indicates that the UV‐C treatment caused irreversible changes in both the chemical composition and morphology of the wood samples via photooxidation and photodegradation processes. Depending on the type of pre‐treatment used, these processes affected the wood samples differently. Copyright © 2014 John Wiley & Sons, Ltd.     

Effects of Low Moisture Anhydrous Ammonia (LMAA) Pretreatment at Controlled Ammoniation Temperatures on Enzymatic Hydrolysis of Corn Stover

Corn stover was treated using low-moisture anhydrous ammonia (LMAA) at controlled ammoniation temperature. Moisturized corn stover (50 % moisture) was contacted with anhydrous ammonia (0.1 g NH₃/g-biomass) in a batch reactor at various temperatures (ambient to 150 °C). After ammoniation at elevated and controlled temperature, ammoniated corn stover was pretreated at various temperatures (60–150 °C) for 72–144 h. Change in composition was marginal at low pretreatment temperature but was relatively severe with pretreatment at high temperature (130–150 °C). The latter resulted in low enzymatic digestibility. It was also observed that extreme levels (either high or low) of residual ammonia affected enzymatic digestibility, while residual ammonia improved by 1.0–1.5 %. The LMAA method enhanced enzymatic digestibility compared to untreated corn stover (29.8 %). The highest glucan and xylan digestibility (84.1 and 73.6 %, respectively) was obtained under the optimal LMAA conditions (i.e., ammoniation at 70 °C for 20 min, followed by pretreatment at 90 °C for 48 h).     

Enhancement of Enzymatic Hydrolysis and Klason Lignin Removal of Corn Stover Using Photocatalyst-Assisted Ammonia Pretreatment

Photocatalyst-assisted ammonia pretreatment was explored to improve lignin removal of the lignocellulosic biomass for effective sugar conversion. Corn stover was treated with 5.0–12.5 wt.% ammonium hydroxide, two different photocatalysts (TiO₂ and ZnO) in the presence of molecular oxygen in a batch reactor at 60 °C. Various solid-to-liquid ratios (1:20–1:50) were also tested. Ammonia pretreatment assisted by TiO₂-catalyzed photo-degradation removed 70 % of Klason lignin under the optimum condition (12.5 % ammonium hydroxide, 60 °C, 24 h, solid/liquid?=?1:20, photocatalyst/biomass?=?1:10 with oxygen atmosphere). The enzymatic digestibilities of pretreated corn stover were 85 % for glucan and 75 % for xylan with NH₃-TiO₂-treated solid and 82 % for glucan and 77 % for xylan with NH₃-ZnO-treated solid with 15 filter paper units/g-glucan of cellulase and 30 cellobiase units/g-glucan of β-glucosidase, a 2–13 % improvement over ammonia pretreatment alone.     

The ammonia sensitivity of platinum-gate MOSFET devices: dependence on gate electrode morphology

The response to ammonia of silicon-based Metal Oxide Semiconductor Field Effect Transistor (MOSFET) devices having either evaporated or sputtered Pt gate electrodes has been studied. A substantial difference in ammonia sensitivity was observed between these two types of device, which is thought to be related to differences in morphology between the two types of gate electrode; devices having evaporated Pt gate electrodes, which are non-continuous, are very ammonia sensitive, whereas devices having sputtered Pt gates, which are continuous, are not ammonia sensitive. However, both the evaporated and sputtered gate devices exhibit a similar response to hydrogen (typically, changes in threshold voltage (V_T) of approximately -420 mV and -350 mV respectively to 500 ppm hydrogen at 150 °C). The ammonia sensitivity of the evaporated Pt-gate MOSFET is dependent on both temperature and ageing effects; the optimum operating temperature of this device is 175 °C, and a burn-in period of approximately 48 h at 200 °C is necessary before the maximum response to ammonia is observed. The humidity response of both evaporated and sputtered Pt-gate MOSFET devices has been studied at 175 °C; a change from 20 to 95% r.h. does not produce a significant response from either of these devices (ΔV_T is typically -35 mV and -5 mV respectively).     

Sweetgum (Liquidambar styraciflua L.): Extraction of Shikimic Acid Coupled to Dilute Acid Pretreatment

Liquidambar styraciflua L., also known as sweetgum, is an understory hardwood species that has widespread distribution in the southeast USA, especially in pine plantations. In addition to being a possible biorefinery feedstock, sweetgum contains shikimic acid, which is a precursor for the drug Tamiflu®. Sweetgum bark was extracted with 65 °C water and yielded 1.7 mg/g of shikimic acid, while sweetgum de-barked wood yielded 0.2 mg/g of shikimic acid. Because shikimic acid can be extracted with water, the coupling of the phytochemical hot water extraction with dilute acid pretreatment was examined. The addition of a 65 °C shikimic acid extraction step coupled to pretreatment with 0.98% H₂SO₄ at 130 °C for 50 min resulted in 21% and 17% increases in xylose percent recovery from bark and de-barked wood, respectively. These results indicate that, in addition to recovering a high value product, the 65 °C wash step also increases xylose recovery.     

Microbial Lipid Production from Enzymatic Hydrolysate of Pecan Nutshell Pretreated by Combined Pretreatment

Biodiesel is a fuel composed of monoalkyl esters of long-chain fatty acids derived from renewable biomass sources. In this study, biomass waste pecan nutshell (PS) was attempted to be converted into microbial oil. For effective utilization of PS, sequential pretreatment with ethylene glycol–H₂SO₄–water (78:2:20, wt:wt:wt) at 130 °C for 30 min and aqueous ammonia (25 wt%) at 50 °C for 24 h was used to enhance its enzymatic saccharification. Significant linear correlation was obtained about delignification-saccharification (R ² = 0.9507). SEM and FTIR results indicated that combination pretreatment could effectively remove lignin and xylan in PS for promoting its enzymatic saccharification. After 72 h, the reducing sugars from the hydrolysis of 50 g/L pretreated PS by combination pretreatment could be obtained at 73.6% yield. Using the recovered PS hydrolysates containing 20 g/L glucose as carbon source, microbial lipids produced from the PS hydrolysates by Rhodococcus opacus ACCC41043. Four fatty acids including palmitic acid (C16:0; 23.1%), palmitoleic acid (C16:1; 22.4%), stearic acid (C18:0; 15.3%), and oleic acid (C18:1; 23.9%) were distributed in total fatty acids. In conclusion, this strategy has potential application in the future.     

Characterization of Fast Pyrolysis Bio-oils Produced from Pretreated Pine Wood

The pretreatment of biomass prior to the fast pyrolysis process has been shown to alter the structure and chemical composition of biomass feed stocks leading to a change in the mechanism of biomass thermal decomposition. Pretreatment of feed stocks prior to fast pyrolysis provides an opportunity to produce bio-oils with varied chemical composition and physical properties. This provides the potential to vary bio-oil chemical and physical properties for specific applications. To determine the influence of biomass pretreatments on bio-oil produced during fast pyrolysis, we applied six chemical pretreatments: dilute phosphoric acid, dilute sulfuric acid, sodium hydroxide, calcium hydroxide, ammonium hydroxide, and hydrogen peroxide. Bio-oils were produced from untreated and pretreated 10-year old pine wood feed stocks in an auger reactor at 450 °C. The bio-oils’ physical properties of pH, water content, acid value, density, viscosity, and heating value were measured. Mean molecular weights and polydispersity were determined by gel permeation chromatography. Chemical characteristics of the bio-oils were determined by gas chromatography–mass spectrometry and Fourier transform infrared techniques. Results showed that the physical and chemical characteristics of the bio-oils produced from pretreated pine wood feed stocks were influenced by the biomass pretreatments applied. These physical and chemical changes are compared and discussed in detail in the paper.     

Isolation and characterization of a novel feather-degrading bacterial strain

Feather waste, generated in large quantities as a byproduct of commercial poultry processing, is almost pure keratin, which is not easily degradable by common proteolytic enzymes. Feather-degrading bacteria were isolated from a Brazilian poultry industrial waste. Among these isolates, a strain identified as kr2 was the best feather-degrading organism when grown on basal medium containing 10 g/L of native feather as a source of energy, carbon, and nitrogen. The isolate was characterized according to morphological characteristics and biochemical tests belonging to the Vibrionaceae family. Keratinolytic activity of this isolate was monitored throughout the cultivation of the bacterium on raw feather at different temperatures. The optimum temperature for growth was about 30°C, at which maximum enzyme and soluble protein production were achieved. The enzyme had a pH and temperature optima of 8.0 and 55°C, respectively.     

Ethanol production from pretreated olive tree wood and sunflower stalks by an SSF process

Olive tree wood and sunflower stalks are agricultural residues largely available at low cost in Mediterranean countries. As renewable lignocellulosic materials, their bioconversion may allow both obtaining a value-added product, for fuel ethanol, and facilitating their elimination. In this work, the ethanol production from olive tree wood and sunflower stalks by a simultaneous saccharification and fermentation (SSF) process is studied. As a pretreatment, steam explosion at different temperatures was applied. The water insoluble fractions of steam-pretreated sunflower stalks and steamed, delignified olive tree wood were used as substrates at 10% w/v concentration for an SSF process by a cellulolytic commercial complex and Saccharomyces cerevisiae. After 72-h fermentation, ethanol concentrations up to 30 g/L were obtained in delignified steam-pretreated olive tree wood at 230°C and 5 min. Sunflower stalks pretretated at 220°C and 5 min gave maximum ethanol concentrations of 21 g/L in SSF experiments.     

Effect of pretreatment reagent and hydrogen peroxide on enzymatic hydrolysis of oak in percolation process

The effect of pretreatment reagent and hydrogen peroxide on enzymatic digestibility of oak was investigated to compare pretreatment performance. Pretreatment reagents used were ammonia, sulfuric acid, and water. These solutions were used without or in combination with hydrogen peroxide in the percolation reactor. The reaction was carried out at 170°C for the predetermined reaction time. Ammonia treatment showed the highest delignification but the lowest digestibility and hemicellulose removal among the three treatments. Acid treatment proved to be a very effective method in terms of hemicellulose recovery and cellulose digestibility. Hemicellulose recovery was 65–90% and digestibilities were >90% in the range of 0.01–0.2% acid concentration. In both treatments, hydrogen peroxide had some effect on digestibility but decomposed soluble sugars produced during pretreatment. Unlike ammonia and acid treatments, hydrogen peroxide in water treatment has a certain effect on hemicellulose recovery as well as delignification. At 1.6% hydrogen peroxide concentration, both hemicellulose recovery and digestibility were about 90%, which were almost the same as those of 0.2% sulfuric acid treatment. Also, digestibility was investigated as a function of hemicellulose removal or delignification. It was found that digestibility was more directly related to hemicellulose removal rather than delignification.     

Kinetics of Lime Pretreatment of Sugarcane Bagasse to Enhance Enzymatic Hydrolysis

The objective of this work was to determine the optimum conditions of sugarcane bagasse pretreatment with lime to increase the enzymatic hydrolysis of the polysaccharide component and to study the delignification kinetics. The first stage was an evaluation of the influence of temperature, reaction time, and lime concentration in the pretreatment performance measured as glucose release after hydrolysis using a 2³ central composite design and response surface methodology. The maximum glucose yield was 228.45 mg/g raw biomass, corresponding to 409.9 mg/g raw biomass of total reducing sugars, with the pretreatment performed at 90°C, for 90 h, and with a lime loading of 0.4 g/g dry biomass. The enzymes loading was 5.0 FPU/dry pretreated biomass of cellulase and 1.0 CBU/dry pretreated biomass of β-glucosidase. Kinetic data of the pretreatment were evaluated at different temperatures (60°C, 70°C, 80°C, and 90°C), and a kinetic model for bagasse delignification with lime as a function of temperature was determined. Bagasse composition (cellulose, hemicellulose, and lignin) was measured, and the study has shown that 50% of the original material was solubilized, lignin and hemicellulose were selectively removed, but cellulose was not affected by lime pretreatment in mild temperatures (60–90°C). The delignification was highly dependent on temperature and duration of pretreatment.     

Maximum Production of Fermentable Sugars from Barley Straw Using Optimized Soaking in Aqueous Ammonia (SAA) Pretreatment

Soaking in aqueous ammonia (SAA) pretreatment was investigated to improve enzymatic digestibility and consequently to increase total fermentable sugar production from barley straw. Various effects of pretreatment process parameters, such as reaction temperature, reaction time, solid:liquid ratio, and ammonia concentration, were evaluated, and the optimum conditions for two of the most important factors, reaction temperature and time were determined using response surface methodology. Optimized reaction conditions were 77.6 °C treatment temperature, 12.1 h. treatment time, 15 wt.% ammonia concentration, and 1:8 solid-to-liquid ratio, which gave a sugar recovery yield of 71.5 % (percent of theoretical sugar recovered from the untreated barley straw) with enzyme loading of 15 FPU/g-glucan. In the optimization of the SAA pretreatment process, ammonia concentration, reaction temperature, and reaction time were determined to be the most significant factors correlated to subsequent enzyme digestibility. Based on tested conditions exhibiting high sugar recovery yields of >60 %, it appeared that reaction temperature affected total fermentable sugar production more significantly than reaction time.     

Chicken Bone as a Bioresource for the Bioceramic (Hydroxyapatite)

Natural hydroxyapatite (HAP) is isolated from waste chicken bone by thermal calcinations at different temperatures in the range of 200 °C to 1000 °C. The isolated HAP has been characterized using thermo gravimetric analysis (TG) and differential thermal analysis (DTA), Fourier Transformed Infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission electron microscope (FE-SEM), and energy dispersive X-ray (EDX). The XRD results showed that the enhanced crystallinity of HAP phase by thermal calcination above 600 °C and the crystal size has been found to increase with increasing temperature of thermal calcinations due to agglomeration. Value addition for the waste chicken bone is given by the isolation of useful bioceramics (HAP) and the optimum temperature for the thermal calcination is found to be 600 °C. The isolated HAP has been characterized as carbonated HAP of B type with the hexagonal structure. These results will not only make the chicken bone as an important bioresource for the HAP but will also reduce the environmental pollution caused by dumping of the waste chicken bone.     

Evaluation and Optimization of Organic Acid Pretreatment of Cotton Gin Waste for Enzymatic Hydrolysis and Bioethanol Production

This paper investigates the efficiency of the organic acids on the pretreatment of an industrially generated cotton gin waste for the removal of lignin, thereby releasing cellulose and hemicellulose as fermentable sugar components. Cotton gin waste was pretreated with various organic acids namely lactic acid, oxalic acid, citric acid, and maleic acid. Among these, maleic acid was found to be the most efficient producing maximum xylose sugar (126.05?±?0.74 g/g) at the optimum pretreatment condition of 150 °C, 500 mM, and 45 min. The pretreatment efficiency was comparable to the conventional dilute sulfuric acid pretreatment. A lignin removal of 88% was achieved by treating maleic acid pretreated biomass in a mixture of sodium sulfite and sodium chlorite. The pretreated biomass was further evaluated for the release of sugar by enzymatic hydrolysis and subsequently bioethanol production from hydrolysates. The maximum 686.13 g/g saccharification yield was achieved with maleic acid pretreated biomass which was slightly higher than the sulfuric acid (675.26 g/g) pretreated waste. The fermentation of mixed hydrolysates(41.75 g/l) produced 18.74 g/l bioethanol concentration with 2.25 g/l/h ethanol productivity and 0.48 g/g ethanol yield using sequential use of Saccharomyces cerevisiae and Pichia stipitis yeast strains. The production of bioethanol was higher than the ethanol produced using co-culture in comparison to sequential culture. Thus, it has been demonstrated that the maleic acid pretreatment and fermentation using sequential use of yeast strains are efficient for bioethanol production from cotton gin waste.     

Pretreatment of yellow poplar sawdust by pressure cooking in water

The pretreatment of yellow poplar wood sawdust using liquid water at temperatures above 220°C enhances enzyme hydrolysis. This paper reviews our prior research and describes the laboratory reactor system currently in use for cooking wood sawdust at temperatures ranging from 220 to 260°C. The wood sawdust at a 6–6.6% solid/liquid slurry was treated in a 2 L, 304 SS, Parr reactor with three turbine propeller agitators and a proportional integral derivative (PID) controller, which controlled temperature within ±1°C. Heat-up times to the final temperatures of 220, 240, or 260°C were achieved in 60–70 min. Hold time at the final temperature was less than 1 min. A serpentine cooling coil, through which tap water was circulated at the completion of the run, cooled the reactor’s contents within 3 min after the maximum temperature was attained. A bottoms port, as well as ports in the reactor’s head plate, facilitated sampling of the slurry and measuring the pH, which changes from an initial value of 5 before cooking to a value of approx 3 after cooking. Enzyme hydrolysis gave 80–90% conversion of cellulose in the pretreated wood to glucose. Simultaneous saccharification and fermentation of washed, pretreated lignocellulose gave an ethanol yield that was 55% of theoretical. Untreated wood sawdust gave less than 5% hydrolysis under the same conditions.     

Effect of alkaline pretreatment on delignification of wheat straw

This study was conducted to analyse structural changes through scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) after alkaline pretreatment of wheat straw for optimum steaming period. During the study, 2 mm size of substrate was soaked in 2.5% NaOH for 1 h at room temperature and then autoclaved at 121°C for various steaming time (30, 60, 90 and 120 min). Results revealed that residence time of 90 min at 121°C has strong effect on substrate, achieving a maximum cellulose content of 83%, delignification of 81% and hemicellulose content of 10.5%. Further SEM and FTIR spectroscopy confirmed structural modification caused by alkaline pretreatment in substrate. Maximum saccharification yield of 52.93% was achieved with 0.5% enzyme concentration using 2.5% substrate concentration for 8 h of incubation at 50°C. This result indicates that the above-mentioned pretreatment conditions create accessible areas for enzymatic hydrolysis.     

Isolation of Cyclodextrin Producing Thermotolerant Paenibacillus sp. from Waste of Starch Factory and Some Properties of the Cyclodextrin Glycosyltransferase

A Cyclodextrin (CDs) producing bacteria was isolated from waste of starch factory in Thailand and identified as Bacillus circulans by biochemical characterization and Paenibacillus sp. by 16S rRNA. The Paenibacillus grew and produced cyclodextrin glycosyltransferase (CGTase) at temperature range 37–45 °C. The optimum culturing conditions for highest CD-forming activity were pH 10.0 and 40 °C for 72 h in Horikoshi broth containing 0.5% soluble starch. The CGTase was partially purified by starch absorption, with 64% recovery and purification fold of 27. The optimum temperatures for dextrinizing and CD-forming activity were 70 and 50–55 °C. At the optimum temperature, the optimum pH for dextrinizing activity was 6.0, while CD-forming activity was 7.0. When the enzyme was incubated for 1 h at different temperatures, CD-forming activity retained its full activity up to 70 °C while dextrinizing activity dropped to 60%. Cyclodextrin products analyzed by HPLC was α:β=1:1, temperature of reaction mixture can affect the yield of CDs.     

Degradability of biodegradable plastic under controlled composting conditions

Biodegradability of poly(ß-propiolactone) (PPL), one of biodegradable plastics, was tested in a bench-scale composting reactor under controlled conditions, with uniform temperature, moisture content, and aerobiosis maintained. The composting raw mixture was prepared by mixing commercial dog food instead of real organic waste, saw dust as a bulking agent, commercial inoculum sold for acceleration of composting, and PPL in the ratio of 10:9:1:10 on dry weight basis. The degree and rate of PPL degradation were determined by comparing the difference in the CO₂ evolution for composting with and without addition of PPL. The influence of temperature on the degradability of PPL was investigated at 40, 50, and 60 °C and the optimum temperature was found to be around 40-50°C where ca. 40 wt.-% of PPL was decomposed in 8 days. The effect of inoculum on the degradability of PPL during 50 °C composting was then examined, a considerable difference (100%) being observed in the biodegradability using two different inocula.