Research Articles

Rapid urbanization and industrialization have led to a substantial increase in sewage sludge production at wastewater treatment plants (WWTPs). WWTP sludge poses significant challenges for municipalities, not only due to the environmental damage caused by existing disposal methods, but also due to energy consumption in storage, drying, and incineration processes, as well as transportation costs. Integrating Thermal Hydrolysis Process (THP) technology into municipal WWTPs offers a sustainable solution by enhancing waste management efficiency and mitigating greenhouse gas emissions (GHGE), while simultaneously yielding eco-friendly byproducts. This study evaluates the characteristics of sludge generated at the Seyhan WWTP in Adana, Turkey—which currently processes approximately 100 tons of sludge daily—with operational projections extending to 2025. The findings indicate that by 2025, THP technology is projected to emit approximately 12,957 kgCO₂eq/ton of GHG, achieving a nine-fold greater emission reduction compared to traditional incineration. Furthermore, the implementation of THP is expected to generate an additional 54 m³/h of biogas and reduce annual dewatered sludge volume by 4,886 tons, resulting in approximately $122,150 in annual operational savings.

The geopolymer field is flourishing, as researchers work to lessen the reliance on conventional cements as building materials. However, high price and energy-intensity of  commercial alkaline activators hamper the usage of geopolymers. Bio-based waste materials are efficacious in mitigating the environmental concerns for alkaline activators, but the synthesis process of this alternative alkali activator requires further research, especially on the optimization for RHA dissolution parameters. The objective of this study was to optimize the alkali treatment process on rice husk ash (RHA) using response surface methodology. The effect of five factors, i.e., RHA quantity, sodium hydroxide concentration, stirring speed, heating temperature, and heating time on two output responses, i.e., activator alkalinity and silica composition of alternative activators, were investigated. Central composite design provided the combination for an optimum alternative activator, which was 162.5 g of RHA quantity, 3M of NaOH concentration, 350 RPM of stirring speed, 75 °C of heating temperature, and 3.5 h of heating time with R² > 0.91 of reduced quadratic models. The activator alkalinity (pH) and silica composition (wt%) for alkali treatment processed activator were 12.1 and 20.3, respectively.

The effects of different drying modes on moisture distribution and cutting power was investigated for beech wood (Fagus sylvatica L.) from northern Poland. Samples (70 mm × 1000 mm) were subjected to air-drying (25 °C) and gas-steam drying (at 90 °C and 105 °C). Moisture content was measured across the cross-section, and cutting power was measured on a narrow-kerf frame sawing machine. The wood resistance was found to depend on moisture content and drying conditions, with higher resistance observed in normal (90 °C) and high-temperature (105 °C) gas-steam drying processes. Cutting power increased linearly with feed per tooth under all drying conditions, ranging from approximately 400 to 1100 W, with the strongest dependence observed for wood dried at 90 °C (r2=0.9364), while both feed per tooth and drying temperature significantly affected the sawing process. Boxplot analysis confirmed clear differences between drying regimes, showing the highest cutting resistance for air-dried samples, while thermally dried wood (90 °C and 105 °C) exhibited lower median cutting power values. Differences between 90 °C and 105 °C were minor. Although drying may influence thermal conductivity and dimensional stability, these effects were minimal at 105 °C due to conditioning, and both feed per tooth and drying temperature significantly affected the sawing process.

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.

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.