Research Articles

Taxodium ‘Zhongshansa’ (T. ‘Zhongshansa’) is a hybrid cultivar of the Taxodium Rich. genus. The wood and fiber characteristics and wood chemical compositions of three T. ‘Zhongshansa’ wood specimens were analyzed and compared with their parents, Taxodium mucronatum (T. mucronatum) and Taxodium distichum (T. distichum). It was found that the wood density of the three T. ‘Zhongshansa’ hybrids were slightly lower than the densities of their parents. The average fiber length and length to width ratio of the three samples were similar and greater than their parents. Runkel ratios of the three T. ‘Zhongshansa’ hybrids was smaller than their patents. Compared to the parents, the extractives contents of the three T. ‘Zhongshansa’ hybrids hardly varied, while the lignin content was slightly lower. The result of the kraft cooking and bleaching of T.Z.502 indicated that with a cooking yield of 44.9%, the kappa number of the kraft pulp was 41.8. The T.Z.502 kraft pulp was easier to delignify via oxygen with alkali, and the brightness reached up to 76% ISO after an elemental chlorine free bleaching process. The results provide a reference for the application of T. ‘Zhongshansa’ wood in pulp and paper making in future.

The effect of different carbon sources was studied relative to the treatment effect of aerobic denitrifying bacteria during the treatment of nitrate-containing wastewater as well as the influence of co-metabolism flora. Three carbon sources, i.e., glucose, citric acid, and sodium acetate, were selected to study the changes in the pH, nitrate nitrogen, chemical oxygen demand removal, nitrite nitrogen concentration, physical and chemical properties of sludge and volatile fatty acids, and high-throughput sequencing to study any changes in flora. The results showed that the denitrification ability of the system using citric acid as the carbon source was stronger than the denitrification ability of the system using glucose or sodium acetate as the carbon source. The removal of nitrate nitrogen in the system was the result of the co-metabolism of acid producing bacteria and aerobic denitrifying bacteria. Due to the greater number of types and greater amount of dominant bacteria in the sludge domesticated and cultured with citric acid as a carbon source, the co-metabolism flora formed was more stable, so it could better remove nitrate nitrogen.

Water is the most widely used fire extinguishing agent. It is used to eliminate a wide range of fires, often occurring in ecologically sensitive areas. There is little information on the toxicity of the fire-fighting substances in connection with aquatic and terrestrial organisms. Toxic substances often present in fire waters slow down life processes. As a result, some organisms die. This study deals with the extinguishing of burning solids (fiberboard, cannabis, straw, cork) with extinguishing water and assessment of its effects on the aquatic and terrestrial environment. The following test organisms were selected to test the effects of the extinguishing water: Daphnia magna – consumer; and Sinapis alba and Lemna minor – producers. A preliminary test was carried out on all the samples to evaluate the (positive / negative) effects of the fire water on the test organisms. Specific conductivity, pH, and chemical oxygen demand were also determined. The results of this study call attention to negative impacts of extinguishing water on the environment. It is necessary to pay attention to prevention and thus eliminate potential risks. If environmental contamination can no longer be prevented, the spread of contaminated water must at least be reduced.

Regression models and a neural net approach were used to predict the cutting performance during milling of Scots pine (Pinus sylvestris L.) by shank cutter. The influence of rake angle, spindle speed, and milling depth on surface roughness of the workpiece, as well as the connection between the milling force and the surface roughness, were thoroughly considered. Four approaches were used to predict the workpiece’s surface roughness based on the experimental data: Back Propagation Neural Network (BPNN), Radial Basis Function Neural Network (RBFNN), Support Vector Machines (SVM), and multiple linear regression. The comparative analysis of the predictive models showed that Neural Network (NN) had preferable performance for prediction of machined surface roughness, with an R2 of 0.98. The SVM had certain fluctuations and the R2 of the multiple linear regression was just 0.87, indicating that they did not fit well for prediction machined surface roughness. In summary, the effective trend of milling parameters on the machined surface roughness of Scots pine was similar to multiple nonlinear regression, and the accurate prediction by BPNN model can provide technical support for the surface roughness of the Scots Pine and enhance shank cutter performance.

This work investigated the ironwood used to construct a gambang, which is a traditional musical instrument. A gambang is constructed from a wooden bar with a similar thickness and width but a different length. The sound and established frequencies were compared with the equal tempered scale. The peak differed from the intended pitch and the partials were not always harmonic. This gambang only classified 4 octaves. The audio classification of the gambang was based on signal processing using a Picoscope oscilloscope. This article explains how wood is transformed into musical instruments. The findings revealed that the sound aspect and sound value of the wood keyboard instruments differed from the desired pitch. The third octave notes created C5, E5, E5, G5, and A5 instead of C5, D5, E5, G5, and A5, while the fourth octave pitch produced C6, D6, E6, G6, and A6# instead of C6, D6, E6, G6, and A6. Only the third and fourth octaves exhibited nearly flawless tuning for the gambang.

The aim of this work was to better understand the ignition method of timber charring in order to improve the industrial process. Three silver fir boards were tied together to make a triangular prism, which acted as a chimney. To start the charring process, the traditional Yakisugi method uses an ignitor paper ball. This ignitor paper ball was in this research replaced with a gas burner. The gas burner supplies the required energy in an even level and provides airflow in the upward direction. The surface temperature of the samples increased from 10 to 500 °C in approximately 40 to 80 s at all recorded positions, which is considerably faster than when using a traditional method. The thickness of the charred layer and the resulting cupping effect were investigated as an indicator of the quality of the process. The charred layer produced by the gas burner method was not as thick as was achieved with the traditional method, which can be attributed to a shorter charring time. Approximately half the specimens showed cupping to the charred side, which may be related not only to a shorter charring time than previous studies, but also to the annual ring orientation of the timber. Further research should be performed on the charred layer thickness and cupping to define all relevant parameters.

Large amounts of plant biomass are produced by public work projects. This plant biomass was evaluated as an aid for the dewatering of sludge from a sewage treatment plant. The relationships were investigated between the different structural types of plant biomass (grass clippings, pruned branches of Japanese black pine, and bamboo powder) and their dewaterability potential in digested sludge. Microscopic observations revealed that grass fibrous materials and Japanese black pine needles had hollow structures. However, xylem, bark parts of Japanese black pine, and bamboo culms exhibited woody cell structures. The difference in water retention value of grass clippings after filtration and centrifugation was higher than that of Japanese pine and bamboo, indicating that the water present within the pores of grass fibrous materials could be easily removed. Plant biomass was captured inside the floc when digested sludge was mixed with plant biomass and flocculation was performed by adding a flocculant. The addition of grass clippings exhibited better dewaterability compared with both Japanese black pine and bamboo. The grass fibrous materials used as a dewatering aid effectively improved the dewaterability of the digested sludge because the water in a sludge floc may be drained from within the grass fibrous materials.

Biomass densification, which is also known as briquetting of sawdust and other agro residues, has been practiced for many years in several countries. The purpose of the present study was to produce fuel briquettes using heat-dried bagasse and to improve their physical properties and thermal value through using varying proportions of bagasse powder as the filler material and lignin as the natural binder. The results showed that lignin had a significant desirable effect on the entire properties of the prepared briquettes. In contrast, as a cellulose-based filler, bagasse powder was also able to significantly improve the thermal energy of the briquettes through increasing the briquettes’ density and mitigating porosity and moisture content. On this basis, according to the obtained results it can be stated that the process of heat-drying, using lignin as the binding element, and using cellulose-based powders, such as bagasse, as the filler are all suitable alternatives to increase the energy yielded by briquettes biomasses.

Azolla filiculoides is an aquatic fern with the potential to become a source of raw materials in a biorefinery system, e.g., a source of soluble and insoluble carbohydrates, proteins, carotenoids, and polyphenols. The fiber chemical content was determined as cellulose (19.2% dry basis) and hemicellulose (7.6% dry basis) content. Azolla has no lignin as a cell wall structure material. Cellulase treatment showed no effect in ethanolic extraction, but polyphenols were found in the enzyme solution at the end of the reaction. The phenolic acids and flavonoids contents of those with health promoting activity were determined, with gallic, syringic, rosmarinic, and p-coumaric the most abundant acids; kaempferol, apigenin, and quercetin were the most abundant flavonoids. The results show that A. filiculoides is a valuable source of bioactive components and cellulosic materials.

Radial and between-clone variations in stress-wave velocity, air-dry density (AD), and mechanical properties in six clones of 5-year-old Acacia auriculiformis trees planted in Vietnam were investigated. The potential to predict modulus of elasticity (MOE) and modulus of rupture (MOR) using stress-wave velocity of standing trees (SWVT) or small specimens (SWVS) was also examined. The examined SWVT, SWVS, and wood properties differed significantly among clones, particularly with two (clones 1 and 6) well suited for A. auriculiformis tree breeding programs focusing on lumber production, as they had the highest static bending values and no significant difference in AD between positions near pith and bark. At the specimen level, the best prediction of static bending properties could be achieved when both SWVS and AD were used in a model for calculation of dynamic modulus of elasticity (MOEd) in air-dry conditions. Significant correlations between SWVT and average MOE (r = 0.83) and MOR (r = 0.61) of test specimens indicated that the use of stress-wave technique for assessing MOE and MOR for selecting the best A. auriculiformis clones in terms of lumber performance was possible.