Yeast cultivation for single-cell protein production using the carbohydrate hydrolysate of steam-exploded eucalyptus wood

This study was aimed at producing single-cell (SCP) protein from the carbohydrate hydrolysate of steam-exploded eucalyptus (Eucalyptus urophylla) wood. Two yeast strains including Saccharomyces cerevisiae and Candida utilis 2.587 were used for batch fermentation. Results showed that the total reducing sugars (TRS), glucose and xylose in hydrolysate had concentrations of 17.52, 10.71, and 4.30 g•L-1, respectively. During fermentation, yeast strains of S. cerevisiae and C. utilis 2.587 used monosaccharides sequentially, and secondary growth occurred. The yeast biomass contained 43.59% crude protein and was rich in all essential amino acids such as lysine, leucine, and valine. Total amino acid reached 401.45 g•kg-1, and corresponded with the standard recommended by the Food and Agriculture Organization of the United Nations for amino acids, except sulfur-containing amino acids.

Properties and use of biomass from reclaimed land in the North Bohemian Basin

Spoil heaps are negative urban landscape features resulting from intense human activities to acquire mineral resources. One very positive method for reclaiming spoil heaps is afforestation. This paper analyzes the quality of Black locust wood acquired from the reclaimed area of Varvažov, North Bohemian Basin, Czech Republic. The following characteristics were used as indicators of the quality of wood obtained from the given area: chip dimensions; ash content; bulk density; bark content; contents of C, H, N, and O; and contents of S, P, Ca, Mg, K, Fe, Zn, and Mn. Black locust biomass is suitable for energy purpose, although it contains an increased proportion of inorganic elements. The other properties, such content of C, H, N, and O, ash content as well as heating value, are in compliance with the standardized values. The Black locust chips can be categorized as Coarse-grained energetic wood chips with minimal dust particle content according to particle-size distribution analysis.

Manufacturing of torrefied pellets without a binder from different raw wood materials in the pilot plant

This paper concentrated on the production of torrefied without an additional binder from different raw wood materials. The torrefaction and pelletizing was carried out at the Torrec Ltd. pilot plant located in Eastern Finland and its effective capacity was 2,200 tonnes per year. Six different woodchips lots were tested in the pilot runs. The test was to identify whether the pelletizing process requires an additional sealant as a binder. The pelletizing process only exploited condensation water that came about from the torrefaction process. The temperature control range and the holding time were varied, regarding the driving parameters. Finally, quality factors were analysed from torrefied pellets and its raw wood materials after each pilot run. The maximum temperature of the reactor, 260°C, was perhaps too low to manufacture pellets of high energy content. Based on the study, the pelletizing process will not require an additional binder in the future.

Influence of die temperature and moisture content on the densification of bamboo powder using die heating method

Residues of agriculture and forestry are usually exploited as feedstock within pellet production for energy producing applications. Some variables such as moisture content and die temperature strongly influence this process. Bamboo powder was used as the experimental material to produce high quality pellet fuel in this paper. A series of experiments involving pellet production were conducted in different die temperatures and at different moisture contents by a newly-developed pellet extruder using a die heating production method. Unit density and densification pressure were tested with four levels of moisture contents (5, 10, 15 and 20%) at five levels of temperatures (40, 80, 120, 160 and 200°C). The surface quality of the pellets was investigated 6 months after the pellets had been produced. The optimum moisture content is around 10% and a suitable die temperature is 160°C to 200°C when producing bamboo pellets.

Aboveground biomass basic density of hardwoods tree species

The influence of tree species on basic density of wood, bark and small-wood was investigated here. Experimental material was obtained from 73 trees of 7 tree species, namely alder (Alnus glutinosa (L.) Gaertn.), beech (Fagus sylvatica L.), birch (Betula pendula Roth.), hornbeam (Carpinus betulus L.), Black locust (Robinia pseudoacacia L.), Sessile oak (Quercus petraea (Matt.) Liebl.) and Turkey oak (Quercus cerris L.) from the territory of Slovakia. Wood and bark samples were taken from discs cut from three trunk sections and from small-wood and branch parts coming from tree crowns. The volume of green samples was measured in graduated cylinders with a precision of 1 ml; a dry matter was measured with a precision of 0.01 g. The statistically significant effect has been shown in tree species, biomass fractions and locations on the tree. The average basic density of all species varies from 440 to 650 kg.m-3 for wood, for bark it is 380-670 kg.m-3 and for small-wood outside bark it reaches 490-650 kg.m-3. Alder and Black locust tree species have the lowest and highest wood density, Black locust and Turkey oak of bark and alder and Turkey oak of small-wood.

Optimisation of acid hydrolysis in ethanol production from Ampelodesmos mauritanicus (Diss)

In this work, statistical modeling and optimization of hydrolyzate from Ampelodesmos mauritanicus (Diss) using 1.5% sulfuric acid hydrolysis was carried. A central composite design (CCD) model was used to study the influence of reaction temperature (70°C to 110°C), ratio (5% to 15%, w/v), and reaction time (60 to 180 min). Reducing sugars, pH, proteins, lignin, ash content and the elements minerals composition were determined. Optimized reducing sugars yield of 0.249 g.g-1 of dry weight was obtained for reaction time of 180 min, reaction temperature of 110°C and ratio 5% (w/v). Therefore, this study tests the production of bioethanol from pure Diss hydrolyzate by the yeast Saccharomyces cerevisiae ATCC 9763. This strain showed a consumption of 67.6% of reducing sugars available (25 g.L-1), which made it possible to obtain ethanol yield per consumed sugar 0.33 g.g-1.

Various lignocellulosic raw materials pretreatment processes utilizable for increasing holocellulose accessibility for hydrolytic enzymes Part II. Effect of steam explosion temperature on beech enzymatic hydrolysis

Beech wood is one of the most abundant species and the most harvested hardwood in Slovak Republic. The structure and chemical composition predetermines beech wood for the second generation bioethanol production. Steam explosion of beech wood from industrial treatment was investigated as a suitable pretreatment method. The effect of steam explosion temperature on beech sawdust enzymatic hydrolysis was investigated. Optimum steam explosion temperature at around 180°C was determined based on concentration of monosaccharides in hydrolysates and concentration of enzymatic hydrolysis inhibitors such as formic acid and acetic acid from beech sawdust. This corresponds to creating conditions resulting in good disintegration to the lignocellulosic structure which leads to increased cellulose accessibility. Non-treated beech sawdust does not enable sufficient cellulose accessibility while excessively high temperature results in significant breakdown of monosaccharides and lignin and formation of inhibitors. The concentration of inhibitors was also determined for each studied steam explosion temperature. Based on steam explosion of beech sawdust, the effect of severity factors was investigated to find the optimum conditions of steam explosion pretreatment on cellulose and xylan recovery of beech wood. The obtained optimum steam explosion temperature corresponds to severity factor R0 = 3.36 (180°C, 10 minutes).

Various lignocellulosic raw materials pretreatment processes utilizable for increasing holocellulose accessibility for hydrolytic enzymes Part I: Evaluation of wheat straw pretreatment processes

New requirements for the biofuels industry force individual enterprises to develop various procedures for newly selected substrates pretreatments that could be applicable in processing of large quantities of raw materials. Even greater pressures are on second-generation biofuels producers justified by selection of waste lignocellulosic substrates and methods of substrate processing. Among the most suitable lignocellulosic raw materials in Slovak Republic (SR) for 2G bioethanol production is wheat straw. This raw material (Senec region, SR) for enzymatic hydrolysis was pretreated by dry milling (Brabender), cyclic freezing and thawing, wet milling (Sprout Waldron), two-step process of steam explosion at 180°C and extrusion at 145°C and one-step process of steam explosion at different temperatures. Wheat straw holocellulose accessibility was tested by adsorption of three commercially available dyes (Pylam Products Company, Inc., USA). Absorptivity coefficient of each dye at its maximum wavelength was determined from individual calibration curves of dyes and their values resulted ranging from 13.78 to 19.52 The absorption of solution was measured and concentration of residual dye was calculated at given wavelength. The accessibility of holocellulose contained in wheat straw pretreated by steam explosion was controlled by SEM (scanning electron microscope) in correlation with the ratio of adsorbed dyes according to the modified Simons’ method.

Influence of kraft lignin on the properties of rubber composites

The influence of lignin content on reclaimed rubber (RR)/natural rubber (NR) blend composite properties has successfully been studied. Scanning electron microscopy (SEM) were used to understand morphology. Fourier-transform infrared spectroscopy (FTIR) for the possible chemical interaction, whereas thermogravimetric analysis (TGA) and tensile tester were used to predict strength and elongation for possible practical applications. The results indicated that the presence of lignin forms cavities which seemed to arise from complex interactions of the blend with the lignin. Those cavities dominated tensile fractured surface and the increase in lignin indicated inconsistencies of interfacial interactions. Lignin RR/NR blend composites revealed a drop in tensile strength and shift in glass transition temperature, except for the highest lignin containing blend composite. More active interactive constituent of the blend appeared to be NR. The interaction has not favored the thermal stability and crosslinking density.