Volume 21 Issue 4

An integrated CaO–Fenton waste-to-resource strategy was evaluated for converting anaerobic sewage digestate into a microbiologically safe and nutritionally functional solution for hydroponic lettuce (Lactuca sativa L.) cultivation. Lime stabilization at dosages up to 35% achieved near-complete pathogen inactivation. Beside substantial decreases in total solids (TS), total volatile solids (TVS), chemical oxygen demand (COD), NH₄⁺ ions, and heavy metals.  Subsequent Fenton oxidation using hydrogen peroxide (H₂O₂) and Fe²⁺ ensured complete microbial sterilization and further improved effluent quality, achieving additional reductions in TS (87.7%), TVS (100%), COD (52.5%), and BOD (52.4%). When applied in a deep-water culture (DWC) hydroponic system, CaO–Fenton-TD supported plant growth with moderate biomass reductions but significantly increased the accumulation of bioactive compounds with potential nutritional value, including ascorbic acid, total carotenoids, total phenolics, and total flavonoids, relative to the control. One-way ANOVA followed by Tukey’s HSD confirmed that both CaO stabilization and Fenton oxidation had significant effects (P ≤ 0.05) on the physicochemical and microbial properties of the digestate. Overall, the results demonstrated the feasibility of using CaO–Fenton-treated anaerobic digestate in hydroponic systems. The proposed approach supports circular economy by promoting nutrient recovery and beneficial reuse of digestate, thereby reducing waste-disposal burdens and dependence on conventional mineral fertilizers.

Long-term anthropometric changes (1980 to 2025) of young adults (aged 18 to 25) were evaluated in the Czech Republic and Slovakia to inform the design of wooden beds. Both populations exhibited identical anthropometric parameters and secular trends: mean body mass increased by 6.2 kg (~1.4 kg/decade) in men and 7.1 kg (~1.6 kg/decade) in women. To address these changes, updated single-bed dimensions are proposed, extending the bed length from 200 cm to a minimum of 220 cm (recommended: 240 cm) and increasing the width from 90 cm to a minimum of 100 cm (recommended: 141 cm). A 3D finite-element (FE) model evaluated structural performance under a design load of 250 kg, which surpasses the reference single-user body mass (~110 kg) specified in EN 1725:2023. The analysis identified the side rails as the most critical structural components. Stiffness was verified against the Eurocode 5 (EN 1995-1-1) L/300 criterion (an 8.0 mm limit for a 2400 mm span). Maximum vertical deflections (6.2 mm for oak and 8.2 mm for spruce) and lateral deflections (5.2 mm and 6.8 mm, respectively) demonstrated that oak satisfies the stiffness requirements, whereas spruce marginally exceeds the allowable deformation limit. The findings confirm that current furniture design standards fail to align with the anthropometric realities and require updates.

Root biomechanical properties, including tensile strength, tensile force, and Young’s modulus, are fundamental parameters governing vegetation-induced soil reinforcement. However, the effects of sample preservation and loading rate on these properties remain insufficiently understood, limiting the reliability and comparability of root biomechanical data. This study investigated the influence of loading rate and freezing preservation on the mechanical properties of roots from four dominant Hyrcanian forest tree species. Fresh roots were tested at two loading rates, and an additional experiment evaluated the effect of one month of frozen storage before tensile testing. Freezing significantly increased tensile force, tensile strength, and Young’s modulus, while also improving the consistency of diameter–property relationships. These increases most likely resulted from structural and moisture-related changes induced by freezing rather than reflecting the natural mechanical behavior of roots, indicating that frozen samples may overestimate root reinforcement capacity. In contrast, loading-rate effects were generally limited and species-dependent. Root diameter increased tensile force but was generally associated with lower tensile strength and Young’s modulus. These findings highlight the importance of standardized testing protocols to improve the reliability of root biomechanical data and the accuracy of soil bioengineering applications.

Cross-laminated timber (CLT) slabs and steel beams can be combined to form hybrid floor systems for long spans and heavy loads. The performance of these systems depends greatly on the shear connections between the CLT slabs and steel beams. In this study, push-out tests were conducted on CLT–steel joints connected with bolts or lag screws. The tests followed the loading procedure specified in EN 26891. Six specimen types were prepared by varying the fastener type, lag screw diameter and length, and reinforcement condition. Carbon fiber reinforced polymer (CFRP) plates were fabricated by laminating pultruded CFRP sheets with epoxy resin, whereas GF plates were fabricated by bonding woven glass-fiber cloth layers with phenol–resorcinol–formaldehyde adhesive. Both types of plates were bonded to the CLT with epoxy resin. CFRP reinforcement increased the strength and stiffness of the joints but resulted in brittle screw fracture. GF reinforcement produced smaller strength gains but showed a more gradual post-peak response. A modified Ramberg–Osgood model was used to describe the nonlinear load–slip behavior. The analytical curves agreed well with the test results (R² > 0.99). The model parameters reflected differences in fastener geometry and reinforcement condition. The results provide useful data for the design and numerical analysis of CLT–steel composite floor systems.

The flatbed die-cutting principles used to convert sustainable dispersion-coated paperboards for food packaging have remained largely unchanged for decades, despite persistent issues with coated-surface integrity after creasing. To improve the convertibility of such materials, this study developed novel die incorporating low-friction plastic creasing rules for industrial die cutters. The die comprised conventional uncoated steel creasing rules as the control condition and interchangeable creasing-rule inserts machined from polytetrafluoroethylene (PTFE) or polyoxy-methylene (POM). The rule contours were surrounded by conventional steel knives to produce standard folding-carton blanks from three dispersion-coated paperboards. The coated surface integrity of the materials was evaluated by measuring the oil and grease resistance (OGR) and performing scanning electron microscopy before and after conversion. The results indicated that the highest OGR was obtained for two paperboards creased with PTFE rules. Die cutting with POM rules improved creasability at specific test points; however, the average performance was comparable to that of steel rules. The third paperboard was particularly prone to damage, precluding a comparison across rules. As the PTFE-based toolset demonstrated superior performance on an industrial die cutter, future research should examine whether die design can be simplified by applying a low-friction PTFE coating to conventional steel creasing rules.

A composite material was fabricated using a hand lay-up technique, incorporating layers of woven kenaf, cotton, and polyester fiber fabrics as reinforcement in a polyester resin matrix, arranged in a specific stacking sequence to enhance its properties performance. The composite material was compressed after the polyester resin was applied in the stacking sequence. Four stacking sequences were designed, and their influence on density, water absorption, moisture content, thickness swelling, tensile strength, flexural strength, and thermal stability was assessed. The PKCCKP sample also exhibited the lowest water absorption (1.99%), moisture content (1.42%), and thickness swelling (0.6%). Tensile and flexural strength attributes were enhanced when all three reinforcement materials were used together.  The optimal stacking sequence for tensile, and flexural strength and modulus was with PKCCKP (52.1 MPa and 133.4 MPa). This improvement can be attributed to the excellent fabric adherence, with polyester fabric playing a significant role in the outside layer compared to the inside layer. All hybrid composite stacking sequences demonstrated good thermal stability, indicating their suitability for various eco-friendly applications. The choice of outer layers affected the durability and mechanical performance of composites for use in automotive, household, and structural applications.

Old ship timber is a wood resource that combines reuse potential, cultural significance, and distinctive aesthetic characteristics. By extending the material life cycle and promoting resource circularity, it provides potential value for sustainable furniture design. However, wood furniture design remains limited by insufficient requirement identification, experience-driven decisions, and inadequate integration of cultural values with contemporary functional needs. To address these challenges, this study focused on Chinese old ship timber furniture and proposes a sustainable design decision-making framework integrating Grounded Theory (GT), Kano model, the Analytic Hierarchy Process (AHP), Quality Function Deployment (QFD), and VIKOR. Semi-structured interviews were conducted with 15 participants to capture users’ perceptions, and GT identified five categories of user requirements—functional, visual, cultural, material, and market-related—comprising 15 elements. Kano classified these requirements, while AHP quantified their relative importance, identifying material expressiveness, ergonomic performance, and style compatibility as the highest-priority requirements. QFD translated these priorities into nine technical characteristics, and VIKOR evaluated four design schemes. Results indicate that Scheme 2, emphasizing the integration of reclaimed ship timber with contemporary living environments, achieved the highest overall evaluation score. The findings suggest that the framework supports requirement identification, technical translation, and alternative selection for sustainable furniture design.

Dissolving-grade pulp (DGP) is a high-purity cellulose feedstock used in the manufacture of regenerated cellulose fibers and cellulose derivatives. Global DGP production is concentrated in regions with established forest-based industries and relies primarily on virgin lignocellulosic resources, including cotton linters, hardwoods, softwoods, and bamboo. These raw materials are typically processed through acid sulfite or prehydrolysis kraft pulping to achieve alpha-cellulose contents above 90%. Compared with virgin feedstocks, recycled fibers exhibit greater variability in morphology and chemical composition, including shorter fiber lengths, lower cellulose quality, and higher levels of residual lignin, ash, inks, fillers, coatings, and other papermaking additives. Consequently, major waste paper streams, such as old corrugated container (OCC), old newspaper (ONP), old magazine (OMG), sorted office paper (SOP), and mixed paper (MP), present distinct challenges for meeting DGP quality specifications. Producing DGP from these secondary fiber resources requires the application of key pulp and paper processing technologies, including repulping, screening, advanced washing and deinking, delignification and bleaching, selective hemicellulose removal through alkaline and enzyme-assisted treatments, and cellulose reactivity enhancement. This review evaluates the technical feasibility of producing DGP from waste paper and highlights both the challenges and opportunities associated with valorizing recycled fibers as a sustainable source of high-purity cellulose.

Agro-industrial residues from the olive oil industry present considerable environmental challenges due to their high organic load and phytotoxic phenolic content. This study explored the valorization of olive pomace by developing pectin, pectin gel, and a biochar–pectin gel composite (BPGC) for sustainable agricultural applications. The materials were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, and Brunauer–Emmett–Teller analysis, confirming successful composite formation and revealing the predominantly mesoporous characteristics of the olive pomace-derived biochar. Swelling analysis showed that pectin reached 121% within 10 min and 195% after 2 h, while BPGC exhibited superior moisture retention (60%) and water-holding capacity (97.9%). Germination studies demonstrated high seed viability (96% to 98%) across treatments, with BPGC producing the highest seedling-growth responses, including shoot length of 8.31 cm, root length of 4.03 cm, and a seedling vigor index of 1210. Enzymatic activity was also improved, with protease and lipase reaching 186 and 201 U/g FW, respectively, in BPGC-treated samples. No detectable phytotoxic effects were observed under the tested conditions. These findings indicate that BPGC is a promising bio-based water-retaining soil amendment for improving soil moisture management and early plant growth, particularly in arid and semi-arid agricultural systems.

Enzyme instability and recovery may limit the practical use of ligninolytic enzymes that originate from white-rot fungus for the management of colored industrial effluents. This study examined the use of a crude cellulose synthesis enzyme preparation from Trametes versicolor in conjunction with a charcoal-based support to treat wastewater from food processing. Spectrophotometric analysis was utilized to assess the conditions of mushroom biomass extraction and charcoal treatment, while FTIR, XRD, SEM, and dynamic light scattering were employed to investigate changes in the charcoal material after modification. The improved charcoal preparation showed alterations in its surface functional groups, scattering profile, shape, and hydrodynamic size distribution; the optimal extraction temperature examined was 30 °C. Shezan International Limited in Lahore provided food-processing wastewater, which was first physically pretreated before being treated with an enzyme preparation and charcoal-based substance. Following treatment, a decrease in UV-Vis absorbance was noted, suggesting color removal. The decrease in absorbance cannot be taken as proof of enzymatic dye degradation because hydrogen peroxide can contribute to chemical oxidation and charcoal can independently absorb color-causing chemicals. The results underline the necessity for quantifiable immobilization, adsorption, stability, and degradation-product studies while supporting the potential of the charcoal-supported ligninolytic enzyme system for additional research.