Research Articles

The microbiological diversity of cultivable bacteria was analyzed in an aerated facultative lagoon. The removal of specific compounds and measures of pollutant load was evaluated with isolated native bacteria, selected and identified in kraft cellulose effluent. The system was operated with an organic loading rate of 0.2 kgCODm-3d-1 for 60 days. Analyses of the fluorescence excitation-emission matrix, acute ecotoxicity, and microbiology were performed. Bioaugmentation tests were done to emphasize the removal of color, using promising species. The removals of biochemical oxygen demand, chemical oxygen demand, and total organic carbon in AFL were 94%, 51%, and 41%, respectively. Regarding color, removal was up to 4%, and the total phenolic compounds were not removed through biological treatment. The treatment also decreased turbidity by 94% and lignin derivatives by 12%. The bacteria identified through NCBI-BLAST and statistical similarity totaled 9 species in the cellulose effluent, three of which have the potential for color treatment: Bacillus cereus, Bacillus thuringiensis, and Paenibacillus sp. The Bacillus cereus combined with biomass removed color (69%), total phenolic compounds (37%), and compounds derived from lignin (53%). These species are promising for removing specific parameters combined with biomass from biological AFL treatment systems.

Due to great advantages, such as simple operation, high porosity, and good fiber continuity, the working principle and research progress of electrospinning technology was studied and polyvinyl alcohol (PVOH) nanofibers were prepared via this process. Air filter paper was used as the receiving substrate to prepare electrospun nano air filter paper (NAFP). The PVOH concentration, static voltage, and receiving distance, were tested to explore the influence of spinning parameters on the filtration performance. Further, the microfiber morphology of the electrospun NAFP was observed. The performance of filter paper, including air permeability, pore size, initial resistance, filtration efficiency, and dust retention, were tested. The results showed that the electrospun NAFP had better filtration performance compared to the air filter paper, and simultaneously they had lower initial resistance and higher precision filtration efficiency. The nanofiber influenced the surface of the air filter paper, as it sharply reduced the pore size. When the spinning condition was 10%, 21 kV, and 15 cm, the pore size decreased approximately 0.6 times of the original, which meant the electrospun NAFP could capture particles ≥ 0.2 μm in size. Finally, after three repeated uses, the good filtration performance was maintained.

In biomass pyrolysis engineering, it is important to develop an industrial catalyst with efficient activity, high selectivity, and a long working life. Dolomite-based porous ceramics were considered in this work. The influence of total corn flour content on the open porosity, compressive strength, and thermal conductivity of dolomite-based porous ceramics was investigated. In order to enhance the catalytic activity, dolomite-based porous ceramics were impregnated with an Al2(SO4)3 solution to load the Al2O3 catalyst. Catalytic fast pyrolysis experiments using corn stalk were conducted with the aforementioned catalyst. The bio-oil yield increased as the open porosity of the dolomite-based porous ceramics increased. The pyrolysis bio-oil yield decreased as the Al2(SO4)3 concentration increased. The phenol content in the bio-oil increased as the Al2O3 load increased. Aluminum oxide not only promoted the formation of phenols in the bio-oil, but it also promoted the conversion of phenols, e.g., 4-ethylphenol and 2, 6-dimethoxy-phenol. The results demonstrated that Al2O3 was beneficial for the formation of phenols during pyrolysis. The results detailing the preparation of Al2O3 loaded dolomite-based porous ceramics can provide a reference for large-scale biomass pyrolysis projects.

A treatment is proposed to sanitize wood for export packaging using radio frequency equipment that is capable of treating wood. This was achieved by optimizing the sanitization process and developing an equation to predict the total sanitization time. Statistical analysis determined that the separation of plates and the power density of the equipment significantly influenced the duration of a sanitization process using radio frequency heating, whereas the thickness of the material was not as influential for the overall process. Furthermore, the sanitization process did not influence the quality of the wood; therefore, the proposed sanitization protocol provided a balance between duration and the quality of the finished radiata pine packaging material.

The effect of plant species on the accelerated weathering behaviors of polyvinyl chloride-based wood-plastic composites (WPCs) was studied. The selected plant species were eucalyptus, rice husk, and bamboo. The color and chemical compositional changes that occurred due to accelerated weathering were monitored using colorimetry and Fourier transform infrared spectroscopy. The lignin and carbonyl contents of the WPCs were altered with exposure. The color change and lightness of the weathered WPCs increased with exposure time, and the degree of increase depended on the plant species. The water absorption and swelling ratio of the WPCs increased with an increase in exposure. The eucalyptus-based composite was the highest ranked in terms of mechanical properties, and the microstructure of the impact section showed that the interfacial bonding performance deteriorated after exposure. In conclusion, the selection of plant fibers is critical to the service performance of WPCs.

To evaluate the static and seismic behaviour of glulam beam-to-column connections with screwed-in threaded rods, nine specimens grouped in three were tested under both monotonic and reversed cyclic loads. The failure modes, moment resistance, initial rotation stiffness, ductility, and energy dissipation capacity of the developed connections were investigated. The results indicated that the developed beam-to-column connections showed superior structural performance. Furthermore, with the introduction of a steel bracket, the hybrid screwed-in threaded rod connection features larger stiffness, higher load-carrying capacity, remarkable ductility, and better energy dissipation capacity. The main failure modes included the yielding of steel brackets, as well as the yielding or rupture of the threaded rods, which indicated a ductile behaviour. The connection specimens with steel columns showed larger stiffness than those with glulam columns, which is reasonable for the bigger compressive deformation of glulam columns.

Pleurotus ostreatus and a newly isolated Ganoderma lingzhi strain were evaluated for their laccase secretion capacity by solid-state fermentation with different agricultural and forestry residues. There was a significant difference among fungi for biosynthetic potential. In principle, the laccase secretion capacity of P. ostreatus CY 568 was stronger than that from G. lingzhi Han 500. Different species of fungi had a preference for agricultural and forestry residues. The presence of cottonseed hull and Populus beijingensis were helpful for accelerating the rate of laccase enzyme production of P. ostreatus CY 568. Cottonseed hull and corncob were useful for improving the production of laccase from G. lingzhi Han 500. Continuous and stable laccase production was found on cottonseed hull by P. ostreatus CY 568 and G. lingzhi Han 500. Maximum laccase activity obtained from P. ostreatus CY 568 on Toona sinensis, Sophora japonica, Salix babylonica, Populus beijingensis, corncob, cottonseed hull, and straw of Oryza sativa was higher than that from G. lingzhi Han 500, and was nearly 1.16-fold, 1.59-fold, 3.32-fold, 1.39-fold, 1.08-fold, 1.08-fold, and 1.36-fold, respectively. These findings will be helpful for developing new productive strains and expanding more species for industrial application to obtain efficient and low-cost laccase.

Three kinds of softwoods (Douglas fir, radiata pine, and Sugi) were used to test the possibility of their classification via near infrared (NIR) spectroscopy. In a previous study, the authors presented that the content of Korean softwood extractives (larix, red pine, Korean pine, cedar, and cypress) influenced wood classification. For expanding the extent of wood species to be considered in the analysis, three foreign wood species were newly introduced. Prior to comparing the NIR spectra obtained from the three softwoods, principal component analysis (PCA) was conducted to evaluate the possibility of discriminating the three foreign softwoods. The three species were also divided into three groups based on PCA, and a thin-layer chromatography (TLC) test improved the reliability of NIR-based wood classification via extractive contents. A similar pattern was obtained for alcohol-benzene eluted extractive compounds between same wood species.

A restoring force model of through-tenon and half-tenon joints was studied with a certain level of universality. To address the differences among data collected under different test conditions, test data collected via through-tenon and half-tenon joints were counted and fitted, and their similarities were then generalized. To better simulate the gap and stiffness degradation between the through-tenon and half-tenon joints, the skeleton curves frameworks were simplified into four phases, namely sliding, elastic, yielding, and failure. The normalized control parameters collected through the characteristics of the framework of through-tenon and half-tenon joints, as well as the different coefficients of strength degradation and stiffness degradation were calculated. The hysteretic rules of the restoring force model of through-tenon and half-tenon joints were developed. Through case study, the results show that the MAPE (mean absolute percentage error) and R2 (coefficient of determination) of experimental data in the references and simulated data of through-tenon are respectively 12.570% and 0.735, while those of half-tenon are respectively 11.763% and 0.772; and the restoring force model of through-tenon and half-tenon joints being constructed had a certain level of universality. The results demonstrated that the construction of refined finite element analysis model of Chinese ancient timber architectures can be simplified to a certain extent to meet the pressing time for seismic performance analysis of many ancient timber architectures. It provides researchers with an innovative pathway to enhance the efficiency of seismic performance analysis of ancient timber architectures.

Because of the diversity of vessel pores in different hardwood species, they are important for wood species identification. In this paper, a Micro CT was used to collect wood images. The experiment was based on six wood types, Pterocarpus macrocarpus, Pterocarpus erinaceus, Dalbergia latifolia, Dalbergia frutescens var. tomentosa, Pterocarpus indicus, and Pterocarpus soyauxii. One-thousand cross-sectional images of 2042 px × 1640 px were collected for each species. One pixel represents 1.95 µm of the real physical dimension. The level set geometric active contour model was used to obtain the contour of the vessel pores. Combined with a variety of morphological processing methods, the binary images of the vessel pores were obtained. The features of the binary images were extracted for classification. Classifiers such as BP neural network and support vector machine were used, the number, roundness, area, perimeter, and other characteristic parameters of the vessel pores were classified, and the accuracy rate was more than 98.9%. The distribution and arrangement of the vessel pores of six kinds of hardwood were obtained through the level set geometric active contour model and image morphology. Then BP neural network and support vector machine were used for realizing the classification of hardwood species.