Volume 21 Issue 3

The paper industry has achieved relatively high levels of recovery and reuse of cellulosic fibers by the recycling of paper. The industry’s record of recovering material from used paper products far exceeds that of, for instance, the plastics industry. However, in the course of that success there are challenges. This paper provides a tutorial review of problems related to the stickies content of recovered used paper material. The review considers what stickies are composed of, how they can affect papermaking and its products, and how papermakers can minimize their adverse effects. Stickies tend to be problematic in mills without deinking systems. Though some stickies can be removed by screening, much of the material is expected to deform and thereby pass through industrial screens. Larger stickies (macrostickies) can be removed using hydrocyclones, whereas smaller ones (microstickies) are often removed using flotation. Other approaches to dealing with stickies include using detackifiers, which essentially means covering the stickies with a polymer or a mineral product. Production teams can optimize conditions to retain the stickies, ideally as small particles, onto cellulosic fibers. Because the processes are complex, and the composition of recovered stock tends to change over time, continuing efforts will be required. Effective control of stickies can be expected to require effective collaboration among people at the mill, chemical supplier companies, and machinery specialists.

Dandelion (Taraxacum officinale) is an edible plant belonging to the Asteraceae family, known for its therapeutic qualities. The antioxidant potential of dandelion leaves was assessed by 1.1-diphenyl-2-picrylhdrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), lipid peroxidation, phosphomolybdenum assay, and metal chelation assays. Results revealed a concentration-dependent antioxidant activity, with DPPH inhibition ranging from 27% to 78%, ABTS inhibition from 55% to 75%, and lipid peroxidation inhibition ranging from 31% to 70% against different prooxidants. Total antioxidant activity was evaluated by phosphomolybdenum reduction assay while metal chelation inhibition was observed between 23% and 58%. Bioactive chemicals in the aqueous extract included total flavonoid content (TFC), which was estimated as 20 mg/g, and total phenolic content (TPC), which is 41 mg/g. In addition to its antioxidant properties, the study also evaluated the antidiabetic potential of dandelion through an alpha-amylase inhibition assay, which exhibited inhibition values ranging from 32% to 77%. These findings suggest that Taraxacum officinale possesses considerable antioxidant and antidiabetic activities, presumably due to the high concentration of flavonoids and phenols in it.

There has been a lack of in-depth research on plywood quality inspection. There are problems that cannot be detected with current methods due to an insufficiency of inspection methods, low inspection efficiency, and the internal nature of some wood defects. This paper describes the design, software, and experimental verification of a new plywood quality inspection system based on air-coupled ultrasound. An ultrasonic C-scanning platform was designed and constructed. Features selected included a core detection devices, signal excitation module, signal processing module, and motion control module design. The software system design included a host computer interface, C-scanning motion control, MCU excitation signal output, serial communication, ultrasonic C-scanning imaging, as well as interpolation algorithms, etc. The validation test during the inspection of plywood shows that the system was able to realize accurate positioning detection of common plywood defects, such as blisters and plywood seams, and determine the location and shape of plywood defects. The above can provide technical support for the online quality inspection of plywood products, which is of high practical significance.

The plywood industry must maintain strict standards of quality if it is to survive the global market competition and be sustainable in terms of resources. In this paper, a quality assessment of meranti (Shorea spp.) plywood in Indonesia is reported, based on QC records from January–December 2024 covering 188,015 panels, which employs the integrated Six Sigma DMAIC and the Seven Quality Tools. The study highlights the major defects responsible for production losses, including insufficient core, thinness, blistering, press marks, and brittleness. An assessment of the performance through Sigma level calculation showed a value of 3.1, computed from the DPMO using five defect opportunities per panel and the conventional 1.5 sigma shift. The use of Fishbone Diagrams and P charts (included in the Results) helped identify process instability and highlight root cause patterns related to machine calibration, operator performance, and thermal variation. Proposed improvements include a proactive maintenance schedule and standardized SOPs for adhesive application and pressing. This approach can be used to scale up yield and quality in the wood-based industry.

Jute fiber powder (0.25% to 2% of cement weight, with a 0.25% increment) was evaluated for reinforcing cement mortars. The addition of jute powder maintains a constant flow diameter of 180 mm, ensuring good workability and homogeneity. This behavior was attributed to the fine particle size and low dosage of the jute powder, which limited its effect on water demand and rheological behavior of the mortar, despite a slight setting delay proportional to the dosage. The low dosage of the jute powder limited its effect on water demand and rheological behavior of the mortar. The incorporation of fibers enhanced internal heat retention, with the material temperature increasing from 44.5 to 45.8 °C as fiber content increased. Although capillary water absorption slightly increased (up to 6.47%), the mortars maintained good compactness and remained within R1 to R3 classes according to NF EN 998-1 (2016). In the hardened state, jute powder improved tensile strength at an optimal dosage of 0.5%, while a progressive decrease in compressive strength was observed, related to changes in the cementitious microstructure. The dosage of 0.5% appeared to be optimal, offering a good balance between mechanical and thermal performance while preserving workability and durability.

Arsenic (As) contamination of freshwater poses a major global public-health challenge. This study evaluated locally isolated freshwater green macroalgae as a feedstock for producing low-cost biochar for As(III) removal from aqueous solutions. Four filamentous chlorophytes, Basicladia kosterae, Stigeoclonium tenue, Cladophora dalmatica, and Spirogyra fluviatalis, were isolated from the Korang River (Islamabad, Pakistan), cultivated in BG11 medium, and combined in equal proportions to form a composite feedstock. The biomass was pyrolyzed at 500 °C under an N₂ atmosphere to produce composite algal biochar. FTIR analysis revealed O–H, C=O, and aromatic C–H functional groups that may contribute to arsenic adsorption, while XRF analysis indicated a high Fe content (~33 wt%), suggesting a role of Fe-(hydr)oxide phases in arsenic immobilization. Batch adsorption experiments were conducted at a biochar dosage of 10 g L⁻¹ using initial As(III) concentrations of 0.05 to 0.5 ppm and contact times of 12 to 72 h. The highest removal efficiency (88 ± 3.5%) was achieved at 0.5 ppm after 12 h. These findings demonstrate the potential of indigenous freshwater algal biochar as an economical adsorbent for arsenic remediation. Further studies involving BET characterization, arsenic speciation, pH effects, post-adsorption analyses, and column-scale testing are needed to clarify adsorption mechanisms and practical applicability.

This review examines the biomethane value chain from feedstock selection and feedstock-specific pretreatment to digester operation, gas upgrading, utilization pathways, and life-cycle constraints. Rather than evaluating biomethane by methane purity alone, it emphasizes the combined effects of feedstock quality, pretreatment intensity, process stability, upgrading energy demand, methane slip, digestate management, and end-use infrastructure. Key anaerobic digestion variables, including temperature, pH, volatile fatty acids, carbon-to-nitrogen ratio, organic loading rate, hydraulic retention time, and inhibitor control, are linked to process robustness. Major upgrading technologies, including water scrubbing, chemical absorption, pressure swing adsorption, membrane separation, and cryogenic separation, are compared in terms of methane purity, methane loss, energy demand, cost tendency and deployment fit. Biomethane shows the strongest mitigation potential when wastes are locally sourced, methane losses are controlled and digestate is safely recycled.

Production of high-purity lactic acid was achieved through fermentation using Enterococcus faecalis (strain 2409), isolated from silage, as the microorganism for converting glucose derived from sago starch. Lactic acid is a valuable organic compound with numerous applications, including food preservation, pharmaceuticals, and the production of biodegradable plastics. The fermentation process was conducted under carefully controlled conditions in a fermenter, with optimal parameters of pH 6.8, 45 °C, and 200 rpm, resulting in a lactic acid concentration of 87 g/L and a purity of approximately 80%. These findings highlight the potential of E. faecalis to efficiently produce lactic acid and demonstrate the viability of utilizing renewable resources such as sago starch for sustainable bioprocessing. Additionally, activated carbon was used to purify the fermentation broth, effectively removing impurities, and enhancing the overall quality of the final product. This approach offers an environmentally friendly and cost-effective solution for the commercial production of lactic acid.

Global wood demand continues to rise while supply from natural forests declines, increasing the importance of forest plantations as a sustainable timber source. In Malaysia, Eucalyptus urograndis has gained attention as a fast-growing plantation species, but stem canker disease caused by Chrysoporthe deuterocubensis threatens timber recovery and value. This study evaluated the effect of infection severity on sawn timber recovery, grading, and value in 11-year-old E. urograndis trees from Sabah, Malaysia. Twelve trees were classified into four infection-severity classes, felled, and sawn using a back-sawing pattern. A total of 404 boards were assessed for dimensions, recovery, visual grade, and disease-related defects using modified Malaysian Grading Rules. Board size shifted toward smaller dimensions as infection severity increased. However, total recovery remained relatively high across classes, and severely infected logs produced the highest volume recovery. Healthy trees yielded the greatest proportion of SELECT and STANDARD grade boards, whereas infected trees produced more downgraded boards. Infection severity was not significantly correlated with log diameter or board volume recovery. These findings indicate that infected E. urograndis logs can still provide commercially usable timber, although with reduced product quality and value.

An environmentally friendly barrier-coating strategy  was studied for fruit-packing tissue paper intended for use in fruit protection bags under humid agricultural conditions. Because tissue paper has high porosity and hydrophilic characteristics, its practical use is limited by low mechanical strength, high air permeability, and poor water resistance. Three coating systems were evaluated using nanofibrillated cellulose (NFC) and a water-based acrylic water-repellent: tissue paper coated twice with NFC, tissue paper coated twice with the acrylic agent, and tissue paper sequentially coated with one NFC layer followed by one acrylic top coating. Double NFC coating increased tensile strength from 2.96 to 4.34 kN/m and improved Gurley air resistance from 34.3 to 114.6 s through pore filling and enhanced inter-fiber bonding. The double acrylic coating provided a water-repellency level of 8 but had limited effects on tensile strength and air resistance. The multilayer coating combined the advantages of both materials, maintaining improved tensile strength, reduced air permeability, and strong water repellency. FE-SEM observations confirmed reduced pore openness after NFC application and continuous film formation after acrylic top coating. These results indicate that sequential coating with NFC and an acrylic water-repellent provides an effective route for improving the barrier performance of tissue paper for fruit protection applications.