Volume 14 Issue 3

This research evaluated a sequential process of thermal-alkali pretreatment, enzymatic hydrolysis, and anaerobic co-digestion applied on a mixture of corn straw (CS) and cattle manure (CM). The results showed that the optimal conditions of thermo-alkaline pretreatment were a Ca(OH)2 dosage of 1.5% and temperature of 120 °C. The optimal conditions of enzymatic hydrolysis in terms of cellulase loading, operational time, and protease loading were determined. Co-digestion with enzymes and thermal-alkali pretreatment achieved the highest methane yield of 0.41 m3 kg-1-VS from the liquid of hydrolysates. An maximum applicable organic loading rate (OLR) of 13.7 kg-SCOD m-3 d-1 was found with a soluble chemical oxygen demand (SCOD) removal of 96.4% in an expanded granular sludge blanket (EGSB) reactor. The optimization of conditions could lead to the industrial-scale treatment of organic solids with a high energy yield and efficiency.

A composite prepared from oil palm empty fruit bunch (OPEFB) and abundantly available wild seaweed showed great potential as a soil stabilizer, which is attributed to its natural hydrophilic nature. The water absorption and thickness swelling percentages of the oil palm empty fruit bunch-seaweed composite (OPEFB-SW) were recorded at 117.2% (± 7.1) and 10.5% (± 1.7), respectively. The main objective of this study was to determine the effectiveness of the biocomposite in regulating runoff volume and water quality due to soil erosion from the experimental plots. Hence, the volume, turbidity, and total suspended solids (TSS) of the water runoff were investigated. A rainfall simulation test was conducted to test the effectiveness of the cover material (biocomposite) at different application levels (0 kg/m2 (T1), 3.0 kg/m2 (T2), 4.0 kg/m2 (T3), and 5.0 kg/m2 (T4)) of the composite in reducing soil erosion. Overall, the OPEFB-SW composite demonstrated its capability to absorb rainfall impact and therefore stabilize the soil structure. The runoff volume, turbidity, and TSS were reduced significantly to 49.1%, 94.6%, and 99.2%, respectively. In addition, the plot with 4.0 kg/m2 indicates the best treatment in regulating runoff volume, turbidity, and TSS.

Frequently sampled process data from a conical disc refiner and infrequently sampled pulp data from a full scale chemi-thermomechanical pulp (CTMP) mill were evaluated to study autocovariance with aspects of potential dynamic modelling applicability. Two trial measurements with an online pulp analyzer at decreased sampling intervals were performed. For variability analysis, time-series containing up to one day of operational data were used. At the chip refiner, the clearest significant autocovariance was identified for the specific electricity consumption, based on the longer sequences. Most of the estimated pulp properties indicated low or non-significant autocovariance, limiting applicability of a specific dynamic model. A mill trial was conducted to investigate the impact from an increase in the conical disc gap on the specific electricity consumption and the resulting freeness. The response time from the gap change in the refiner to measured change in freeness was estimated at 19 min, which was approximately the hydraulic residence time in the latency chest. The relevance of this study lies in applicability of mill-data-driven modelling to capture the dynamics of a specific refining process. Through mill trials the sampling speed of pulp properties was more than doubled to gain insights into short term systematic variations by applying time-series-analysis.

Autohydrolysis and kraft pulping were sequentially applied to Eucalyptus urograndis wood to obtain added-value products from hydrolysis liquor. A biorefinery approach was used to bleach the resulting solid phase containing the cellulose pulp with an optimized O–D–(EP)–D bleaching sequence, where O denotes delignification with the sequence D bleaching with chlorine dioxide and EP alkaline extraction with soda and hydrogen peroxide. The pulp was then beaten to obtain paper sheets. The two-stage process yielded pulp with a small Kappa number relative to conventional delignification (4.9 to 13.7 vs 17.1). Using autohydrolysis temperatures of 160 °C to 170 °C during 0 min to 15 min made the process selective towards the extraction of hemicelluloses (xylan up to 43.9%). Additionally, the Kappa number and brightness obtained after bleaching with an O-D-EP-D sequence were suitable for preparing dissolving grade pulp. The brightness of the pulp obtained was identical with that of the reference pulp (91.0%) and the Kappa number was smaller (0.2 to 0.6). Beating the pulp for 4500 PFI revolutions produced paper sheets with slightly better tensile strength and tear index than those for sheets from the reference pulp (viz., 90.3 N·m·g-1 and 9.9 mN·m²·g-1, respectively, versus 89.8 N·m·g-1 and 9.7 mN·m²·g-1, respectively).

Employee motivation is a prerequisite for the effective development of the potential of human resources. Therefore, motivation processes are important. The aim of the paper was to define the motivational priorities of white-collar employees in forest enterprises. Following the research results, cluster analysis statistical methods were used to define employee groups with similar motivations. The research was carried out in 11 forest enterprises with 195 total respondents. The results indicated that it is possible to create a unified motivation program with selected motivation factors for white-collar employees in forest enterprises. Defined groups had similar levels of motivation in individual motivation factors. Three significant motivation factors were determined: basic salary, working environment, and fair appraisal system. These motivation factors can be systematically implemented as a tool to improve the level of motivation of individual groups. It is important to consider that conditions and work environments change over time, so an effective motivation program must be updated regularly in order to produce sustained benefits.

The production of environmentally friendly thermal insulation boards is important for the building industry to reduce its environmental impact. The primary objective of this study was to test the feasibility of producing wood-based insulation panels as well as to use fungi as a binding agent and to explore whether a bio-based composite could be a viable alternative to the standard traditional foam insulation board and more expensive wood fibreboards (mainly available in European markets). Experiments were conducted to determine which combinations of wood fibers from selected northern tree species, wood decay fungi, and growth conditions were most suitable for panel making. The results showed that under the determined optimal growth conditions, Polyporus arcularius and Trametes suaveolens on birch wood shavings provided the best combination. Outcomes from initial physical screening tests, particularly thermal conductivity, suggested that these panels had a comparable performance to traditional insulation material.

Three zinc-phosphate-solubilizing fungi (ZPSF) were isolated from rhizospheric soil cultivated with Sorghum bicolor L. The fungal isolates were identified as Aspergillus chevalieri, Fusarium moniliforme, and Trichoderma harzianum. The results showed that halo zone formation by ZPSF on Pikovskaya (PVK) agar medium plates was an indicator of zinc phosphate (ZP) solubilization. The lowest in pH of the inoculated medium containing ZP was observed with A. chevalieri, followed by T. harzianum, followed by F. moniliforme, compared with the initial pH (6.5) of the non-inoculated medium. ZP solubilization processes at different temperatures (10 °C, 20 °C, 30 °C, and 40 °C) were conducted using ZPSF at different doses of ZP (0.5 g/L, 1 g/L, and 2 g/L). The released P, to P2O5, was monitored during the solubilization process. The released phosphorus increased as the temperature increased, with the greatest values of phosphorus obtained with F. moniliforme, A. chevalieri, and T. harzianum being 11.54 mg/L, 24.40 mg/L, and 28.40 mg/L, at 30 °C and a dose of 2 g/L of ZP, respectively. In contrast, the smallest values of phosphorus were 11.89 mg/L, 8.2 mg/L, and 7.97 mg/L, at 10 °C and a dose of 0.5 g/L of ZP, with F. moniliforme, A. chevalieri, and T. harzianum, respectively.

Photocatalytic carbonized medium density fiberboard (MDF) was prepared by one-step carbonization with titanium tetraisopropoxide (Ti-tip) as a TiO2 precursor. Anatase TiO2 was formed at carbonizing temperatures of 600 to 800 °C. However, at > 900 °C, most crystalline TiO2 was rutile. Ti-tip-treated carbonized MDF (c-MDF) showed outstanding formaldehyde reduction performance with complete removal of formaldehyde from the chamber in 1 to 3 days. However, with non Ti-tip-treated c-MDF, formaldehyde remained after 20 days. No toluene was detected after 3 h on 50% Ti-tip-treated c-MDF, while toluene was continuously detected with other samples (10% and 5% Ti-tip-treated c-MDF, and untreated c-MDF). After 9 h ultraviolet exposure, toluene was completely reduced on 10% and 50% Ti-tip-treated c-MDF; reduction was only 20% on untreated c-MDF. In addition, c-MDF/TiO2 prepared at 800 and 900 °C had significantly higher photocatalytic performances compared to those obtained at lower carbonization temperatures. Based on the results, the combination of 10% Ti-tip treatment and carbonizing at 800 °C provided the optimum photodegradation capacity for formaldehyde and toluene.

The objective of this study was to evaluate the possibility of producing dissolving grade pulp from tobacco stalk through combining SO2-ethanol-water (SEW) fractionation, alkaline extraction, and bleaching with oxygen (O), chlorine dioxide (D), alkaline extraction with hydrogen peroxide (Ep), and hydrogen peroxide (P) (OD0(Ep)D1P). The results showed that the optimum SEW cooking condition to remove the original xylan and lignin in tobacco stalk to an acceptable level was 6% SO2 charge (by weight) at 135 °C for 180 min. A bleachable pulp (Kappa number of 21.5) was produced from the SEW-treated tobacco stalk via a subsequent 1% NaOH extraction. After the OD0(Ep)D1P sequence bleaching, the bleached pulp showed a high brightness (88.1% ISO) and a high α-cellulose content (94.9%). The viscosity (15.8 cP) and the residual xylan content (4.4%) of the pulp were within acceptable levels for dissolving pulp production. Thus, tobacco stalk was shown to be a viable raw material for dissolving pulp production following a SEW treatment, alkaline extraction, and a conventional bleaching sequence.

Cross-laminated timber (CLT) is an engineered wood material that is used in the construction industry, e.g., for floors, walls, and beams. In cases where CLT-elements are used as shear walls, the in-plane-stiffness is an important property. For non-edge glued CLT, in-plane shear stiffness is lower than for edge-glued CLT. To evaluate the non-edge glued CLT panel’s in-plane shear modulus, the diagonal compression test and finite element (FE) simulation was used. FE-models with both isotropic and orthotropic material models were used to calculate the shear stiffness. The FE models using pure shear loads were used as a reference to determine the correct value of the shear modulus. To verify the FE simulations, diagonal compression tests were conducted on 30 CLT samples. A calibration formula was derived using the least square method for calculation of shear modulus. The formula gave accurate results. The results showed that FE simulations can reproduce the same shear stiffness as tests of non-edge glued 3-layer and 5-layer CLT panels.