Search Results (18,303)

The management of waste bentonite slurry (WBS) produced during slurry shield TBM excavation involves environmental and operational challenges from the perspective of developing a more sustainable tunnelling construction process. In this study, the potential reuse of WBS as a complete replacement for bentonite in two-component grout formulations used for TBM backfilling is explored. A comprehensive laboratory testing program is conducted, in which the effects of WBS on the properties of two-component grout (unit weight, viscosity, bleeding, gel time, and mechanical strength) are assessed after various curing times, and the outcomes are compared with standard values commonly given in technical specifications. WBS produced from two different commercial bentonites is investigated. The results show that while the first formulation exhibits rapid setting and irregular gelation, the mix derived from the second bentonite demonstrates superior mechanical performance, increasing compressive strength by up to 40%. This enhancement is primarily governed by a physical filler effect, where fine soil particles optimize packing density and refine the microstructure. Consequently, the incorporation of selected types of WBS into a two-component grout could be a practicable approach, since it offers benefits in terms of mechanical performance, although careful mix design would be required to manage workability. This study shows how tunnelling can become more sustainable by reusing excavation waste and transforming it into a useful by-product. Full article

This study explores how residents of Vrnjačka Banja (Serbia) perceive the impacts of tourism and how these attitudes influence their support for future tourism development. Specifically, it examines positive and negative economic, socio-cultural, and environmental impacts, as well as the types of tourism residents favor. Data were collected from 420 local residents using a structured survey, and the reliability of the scales was confirmed using Cronbach’s alpha. Descriptive statistics provided an overview of participant characteristics, while MANOVA and follow-up ANOVA tests were used to examine differences in perceived tourism impacts across tourism types. Multiple linear regression was used to assess how attitudes toward positive and negative impacts predict residents’ support for future tourism development. The results indicate that attitudes toward positive impacts are relatively consistent across residents, whereas negative socio-cultural and environmental impacts differ depending on the type of tourism they support. Regression analysis shows that positive socio-cultural and environmental impacts are the strongest drivers of residents’ support, while negative socio-cultural and economic impacts reduce support. These findings highlight the importance of social and environmental considerations in shaping community attitudes and suggest that sustainable tourism planning should prioritize local well-being and responsible environmental management alongside economic objectives. This study contributes to the literature by addressing the heterogeneity in residents’ attitudes through tourism type preferences, while also highlighting the limited research on this topic in spa destinations. It further provides practical guidance for destination managers and policymakers in developing more targeted and sustainable tourism strategies. Full article

Depletion of reserves of rich copper–porphyry ore deposits necessitates the development of highly efficient methods for Mo (VI) extraction from complex, corrosive hydro-metallurgical media. The present study undertakes a comprehensive assessment of sorptive concentration of Mo (VI) from strongly acidic sulfate solutions (120 g/L H₂SO₄) by employing a spectrum of commercially available strong- and weak-base anion-exchange resins. It has been established that the macroporous weak-base anion exchanger Purolite A-100 demonstrates decisive superiority over gel-type analogs (Lewatit M-800, AB-17), facilitating unimpeded intra-gel diffusion of bulky molybdenyl sulfato-complexes anions, thereby circumventing the obstructive “sieve effect.” Thermodynamic and kinetic investigations revealed that the sorption process exhibits pronounced concentration- and pH-dependent characteristics. Peak extraction efficiency (up to 95.91%) is achieved at pH ≈ 1, a finding that correlates with the region of maximal protonation of tertiary amino groups within the resin matrix. Kinetic acceleration of mass transfer upon heating to 80 °C has been experimentally confirmed, yielding 94.6% extraction within 60 min. The obtained results corroborate the prospective integration of macroporous weak-base anion exchangers into operational hydro-metallurgical schemes as an environmentally benign and efficacious alternative to conventional solvent extraction of molybdenum. Full article

The energy utilization of residual woody biomass is a relevant strategy for the decentralized energy transition and local waste management in rural areas. The objective of this study was to characterize (physically, chemically, and energetically) five types of residual biomass: pine branches, huinumo (this material refers to the long, thin pine needles that, after drying and falling, form a layer on the forest floor), cherry branches and leaves, and grass waste generated in the community of San Francisco Pichátaro, Michoacán, Mexico, in order to evaluate its viability for the production of densified solid biofuels. A comprehensive analysis was conducted, including moisture content, higher heating value, proximate characterization, structural chemical analysis (using the Van Soest method), elemental CHONS analysis, ash microanalysis (by ICP-OES), and a multicriteria analysis with normalized energy and compositional indicators. The results showed that huinumo and cherry leaves were the most outstanding biomasses, presenting the highest heating values (20.7 MJ/kg) and low moisture and ash contents. Pine branches obtained the most balanced results, characterized by their equilibrium in fixed carbon and lignin, as well as their low potassium content. The multicriteria analysis showed that there is no absolute optimal biomass; however, it indicates that pine branches and huinumo are the most robust feedstocks for the production of briquettes or pellets. The results confirm the significant technical and environmental potential of local lignocellulosic residues for the production of solid biofuels and for contributing to sustainable energy solutions at the local scale. Full article

Formaldehyde emissions from urea–formaldehyde (UF)-bonded particleboards remain a significant environmental and health concern. This study evaluates the effectiveness of flours as bio-based formaldehyde scavengers in particleboard production. Food-based flours (soy, wheat, green pea) and feed flours (hemp, maize DDGS, feather meal) were incorporated into UF resin at concentrations of 0.3–2.0%. Resin characterization included pH, viscosity, gelation time, solid content, and free formaldehyde, while rheological behavior was monitored at 70 °C and 90 °C. The addition of flour decreased pH from 9.1 to 7.9 and increased viscosity from 414 to up to 1600 cP, depending on flour type and dosage. Free-formaldehyde content was reduced from 0.17% to as low as 0.08%, with the most effective reduction observed for hemp flour. At industrial scale, particleboards produced with 0.5% soy and hemp flours significantly reduced free formaldehyde, with emission values of 3.26 mg/m² and 3.05 mg/m², corresponding to reductions of 66–70% compared to the reference (3.97 mg/m²). Mechanical properties, including density (652–665 kg·m⁻³), bending strength (13.2–14.1 N·mm⁻²), and internal bond (0.42–0.45 N·mm⁻²), were maintained within acceptable limits. While feed flours such as feather meal showed strong scavenging potential, they caused significant viscosity increases (up to 1800 cP), limiting processability. These findings demonstrate that adding low levels of flour, particularly soy or hemp, is an effective, renewable, and low-cost strategy to reduce formaldehyde emissions in UF-bonded particleboards, supporting the production of safer and more sustainable wood-based composites. Full article

Bio-based, biodegradable, and renewable polymers offer a promising alternative to traditional synthetic polymers derived from petroleum or other non-renewable resources. However, their use is limited by suboptimal properties and high costs. Incorporating sustainable reinforcements into the polymer matrix significantly improves biopolymer performance while preserving key properties, sustainability, and cost-effectiveness. Bio-based polymeric composites have emerged as a crucial category of biopolymers, playing a key role in advancing a sustainable, circular economy. This review provides an updated overview of bio-based polymer composites and nanocomposites, focusing on reinforcement strategies using natural nanofillers and engineered nanoparticles. We summarize key synthesis and processing methods, discuss structure–property relationships, and highlight recent advances in applications such as food packaging, biomedical devices, energy systems, environmental remediation, 3D printing, and supercapacitors. Polymer nanocomposites are versatile, with their performance depending on the type, size, and interactions between the fillers and the polymer matrix. Progress in metallic, ceramic, carbon-based, natural, and hybrid fillers has improved their properties. Using bio-based polymers and renewable fillers supports sustainability. Natural nanofillers derived from renewable sources and industrial byproducts offer a sustainable approach to developing high-performance, biodegradable nanocomposites. Smart nanocomposites can react to external stimuli by integrating specialized fillers that enhance their mechanical and mobility properties. Shape memory nanocomposites can be remotely activated—using heat, electricity, magnets, or light—enabling advanced applications. Finally, we address major challenges and outline future directions for scalable, circular-material solutions, drawing on perspectives from the circular economy and life cycle assessment (LCA). Full article

This study presents a source-specific experimental evaluation of particle board waste sludge (PBWS), a sludge-type industrial by-product from the wood-based panel industry, as a partial cement replacement in Portland cement paste systems. The hydration-related behavior of cement pastes containing 0%, 5%, 10%, and 20% PBWS at 7, 28, and 90 days was investigated using Fourier Transform Infrared Spectroscopy (FT-IR), X-Ray Diffraction (XRD), and Thermogravimetry/Derivative Thermogravimetry (TG/DTG). The results showed that PBWS affected phase development and thermal decomposition behavior depending on replacement level and curing age. In the TG/DTG analysis, mass losses in the 30–230 °C region were generally higher in the PBWS-containing mixtures than in the reference paste, particularly at 28 and 90 days, suggesting differences in dehydration-related phase development. FT-IR and XRD results further showed that PBWS modified the evolution of hydration-related phases in the blended systems. From an environmental perspective, increasing PBWS replacement reduced the calculated energy intensity, CO₂ emissions, and production cost; at 20% replacement, these values decreased from 3300 to 2654 MJ/t, from 830 to 706.77 kg/t, and from 3400 to 2867.16 TL/t, respectively. Overall, the results indicate that PBWS has the potential to improve the environmental profile of cement-based production while influencing hydration-related phase evolution in blended paste systems. Full article

(1) Background: University food service establishments are complex environments, where high turnover and handling practices create conditions for microbial persistence. Food-contact surfaces (FCSs) and handlers’ hands (FHs) function as dynamic reservoirs, facilitating the circulation of contaminants within these institutional settings. This study aimed to characterise the microbiological contamination of FCSs and FHs in university food service establishments in Northern Portugal and to evaluate their role as interconnected environmental reservoirs within the indoor built environment. (2) Methods: A total of 590 samples were analysed from two universities in Northern Portugal (L1, L2), comprising 380 FCS and 210 FH samples. Aerobic colony counts (ACCs), Enterobacteriaceae, and Moulds and yeasts (MYs) were analysed according to ISO methods. FH samples were additionally screened for Escherichia coli and Staphylococcus spp. (3) Results: Overall, 35.5% of FCSs were classified as non-compliant, according to microbial criteria based on guideline values from the National Health Institute Dr. Ricardo-Jorge (INSA), with non-compliance primarily driven by elevated ACCs and MYs. Based on a Generalised Linear Model (GLM), establishment types (canteens vs. cafes) were associated with Enterobacteriaceae levels (p = 0.016), whereas ACCs and MYs were not significantly associated with district, establishment type, or functional surface category (p > 0.05). Differences between left and right hands showed small effect sizes, and location was a highly significant determinant of hand hygiene acceptability. (4) Conclusions: FCSs and FHs act as relevant contamination reservoirs in these settings. The results indicate that Enterobacteriaceae levels on FCSs differed between establishment types, while ACCs and MYs showed no significant variation across the evaluated environmental factors. Marked differences in hand hygiene acceptability between campuses support the implementation of targeted interventions, including the optimisation of cleaning and disinfection protocols, the structured training of food handlers, and the routine microbiological monitoring of surfaces and hands to improve institutional food safety. Full article

This study presents the results of research on the modification of gypsum with bio-waste to improve its thermal insulation properties and to evaluate the influence of the type and amount of the additive on the physical, mechanical, and microstructural properties of the composite. Various fractions of plant-based bio-waste were used in amounts ranging from 0.75 to 10% by weight. The thermal conductivity coefficient and thermal diffusivity were determined. Additionally, analyses of dimensional stability over time, visual appearance, and phase distribution uniformity were conducted. Mechanical tests included surface hardness measurements. In order to determine the material’s durability, water absorption and frost resistance tests were performed, and structural changes and properties after these cycles were analyzed. It was found that selecting the appropriate type and proportion of additive makes it possible to obtain composites with a favorable balance between thermal insulation, dimensional stability, and mechanical performance. The conducted research confirms the potential for effective use of bio-waste as a gypsum-modifying raw material, contributing to the development of sustainable building materials with a reduced environmental footprint and improved functional parameters. Full article

The large-scale generation of industrial waste salts (IWSs) across sectors such as coal chemical, pesticide, pharmaceutical, and dye manufacturing has raised increasing environmental and regulatory concerns. These IWSs often exhibit complex physicochemical profiles—featuring high concentrations of inorganic salts, persistent organic pollutants, and trace heavy metals—that pose significant challenges for both safe disposal and resource recovery. This review provides a comprehensive and pollutant-oriented overview of industrial waste salts, focusing on their sector-specific characteristics, dominant contaminant types, and tailored treatment strategies. Removal pathways for organic matter (e.g., thermal decomposition, advanced oxidation) and inorganic impurities (e.g., precipitation, ion exchange) are systematically analyzed, followed by technical pathways for salt separation based on crystallization and membrane processes. Resource utilization routes for major salt components, particularly NaCl and Na₂SO₄, are critically assessed in terms of technical feasibility, impurity tolerance, and end-use compatibility. The emergence of reclaimed salt quality standards and sector-specific impurity thresholds reflects a paradigm shift from purity-based to performance-based reuse evaluation. Finally, the review highlights future priorities including adaptive impurity control, downstream-specific salt grading, and enforceable regulatory frameworks to ensure the safe, scalable, and circular deployment of reclaimed salts in industrial systems. This study supports the coordinated advancement of control technologies and reuse standards, enabling the transformation of waste salts from environmental liabilities to secondary resources. Full article

Blue-green infrastructure in high-density communities has been found to be vital to the well-being of urban residents, particularly in 15 min walkable communities. However, residents’ environmental preferences for blue-green infrastructure in high-density urban areas have received little attention. This study uses a walking interview method with 90 participants to explore residents’ motivations, activities and preferences in both community and riverside green spaces. The study area centers on the Licun River and surrounding communities within a 15 min walking distance of the river in Qingdao, China, a high-density city promoting 15 min walkable communities. The findings showed that relaxation was the main reason for visiting both types of spaces. Riverside green spaces supported a wider variety of activities but notable differences in preferences for particular spaces, particularly across gender and age groups. Within community green spaces, artificial elements had a stronger impact on preferences, whereas in riverside green spaces, natural elements were more influential. Blue-green infrastructure planning in high-density cities should then consider diverse user needs by accounting for demographic differences and adapting design elements to various spatial contexts. Since a 15 min walk is not feasible for all residents, enhancing the safety, walkability and inclusivity of blue-green infrastructure is essential for everyday use. Full article

Aiming at the rain protection problem of outdoor precision instruments such as total stations, this paper designs an environmentally adaptive intelligent protection system based on D-S evidence fusion and state machine control. In terms of mechanical structure, the protective cover is designed as a sinking type, which not only improves the safety of the equipment but also avoids the shielding problem of the working surface compared with the traditional upward-lifting structure. The system collects data from multi-source meteorological sensors and uses D-S evidence theory for fusion decision-making. To alleviate decision conflicts in high-conflict scenarios, a conflict-guided dynamic weight adjustment strategy is introduced. Combined with a dual-layer finite state machine, the system realizes coordinated control between environmental perception and protection actions and can activate protection within 30 s under severe weather. Simulation results show that the improved method increases the response speed by 41.9–62.5% compared with traditional D-S fusion in weather transition conditions. In a 28-day field test, the system achieves a daily protection success rate of 96.4% and 100% reliability in critical weather transitions. The proposed system can provide reliable support for the all-weather safe operation of field precision measurement equipment. Full article

Nontuberculous mycobacteria (NTM) are ubiquitous environmental organisms capable of causing diverse clinical manifestations. Their epidemiology among people with HIV remains insufficiently characterized. This study examined the epidemiology of NTM among people with HIV admitted to the Hospital for Infectious Diseases in Warsaw between 2017 and 2023. Data on CD4+ T-cell counts, type of NTM involvement, species identification, and antimicrobial resistance were obtained from medical records. In the analyzed group the median of the CD4+ T-cell count was 25 cells/mm³ (IQR 65 cells/mm³). Late HIV diagnosis was observed in n = 45/50 (90.0%) patients. NTM colonization was identified in n = 20 (33.9%) patients, while n = 39 (66.1%) had active NTM disease, including pulmonary (53.9%), disseminated (41.0%), and extrapulmonary (5.1%) forms. Mycobacterium kansasii was the most common species among colonized patients, n = 7/24 (29.2%), whereas Mycobacterium avium predominated among patients with NTM disease, n = 30/42 (71.4%). Among patients with NTM disease, in vitro resistance to at least one antimicrobial agent was observed in 80.0% of M. avium isolates. High levels of resistance of M. avium were noted for ethambutol (n = 8/8, 100%), moxifloxacin (n = 16/22, 72.8%) and linezolid (n = 9/21, 42.9%). Proper identification of Mycobacterium species and its antibiotic resistance might be helpful in selecting effective antimicrobial therapy. Early HIV diagnosis is needed to prevent NTM disease. Full article

The use of biostimulants in agriculture is increasing; however, their effects on raspberry remain insufficiently understood. The aim of this study was to evaluate the impact of foliar-applied biostimulants on yield and growth in three primocane raspberry cultivars grown under field conditions using multispectral imaging based on unmanned aerial vehicles. An experiment included a control and four foliar biostimulant treatments based on animal-derived amino acids, plant-derived amino acids, seaweed extract, and seaweed extract combined with animal-derived amino acids. Biostimulant effects on primocane raspberry were found to vary substantially depending on cultivar, environmental conditions, and formulation type, with measurable impacts on both yield formation and vegetative growth. These responses were further supported and characterized using multispectral UAV-based mutlispectral imaging, which enabled effective detection of treatment-related physiological changes. This approach was based on the analysis of relative percentage changes between consecutive measurements of selected vegetation indices, allowing the identification of dynamic physiological responses over time. These findings highlight the need for a more targeted approach to biostimulant use, taking into account cultivar-specific responses and environmental variability. Future research should extend this framework to a broader range of genotypes, cultivation systems, and biostimulant formulations, while integrating remote sensing with other analytical methods to better understand plant physiological responses. Such developments may support the transition toward data-driven and precision-guided biostimulant application strategies in sustainable crop production. Full article

Urban trees deliver multiple ecosystem services. However, rapid climate change may alter species-specific growth suitability, necessitating climate-informed planting and management. We developed 1 km grid-based ensemble species distribution models (ensemble SDMS) for 18 tree species widely planted in South Korean cities and projected growth suitability under SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5 across four future periods (2021–2040, 2041–2060, 2061–2080, 2081–2100) relative to a historical baseline (2000–2019). We quantified multidimensional redistribution signals from SDM outputs, including binary suitable area changes, centroid displacement, latitudinal boundary shifts, and mean suitability changes, using multivariate climatic predictors and complementary environmental variables. These indicators were integrated to classify species responses into four management-relevant types: Stable, Northward Expansion, Poleward Shift, Range Contraction. Model performance was generally high (AUC = 0.74–0.97). Although the median change in suitable area remained near 0%, interspecific variability increased toward later periods and under stronger forcing, with the largest dispersion under SSP3-7.0 (2041–2060). Stable type was most frequent overall (36.8–63.2%), but Northward Expansion increased to 42.1% under late-century SSP3-7.0, and Range Contraction reached 36.8% under mid-century SSP3-7.0. This indicator-based typology provides a practical basis for decision-support tools to prioritize climate-adaptive urban tree selection, replacement, and monitoring. Full article