Search Results (13,809)

Accurate prediction of settling velocities for irregular particles offers significant advantages in various fields, including more efficient water/wastewater treatment, environmental pollution control, industrial productivity, and sustainable resource utilization. These predictions are essential for advancing sustainable hydraulic engineering and environmental management. In this study, a new algorithmic modeling framework was proposed to estimate the terminal settling velocity of irregularly shaped particles/materials. The framework integrates advanced non-linear regression techniques with robust optimization methods. The model successfully incorporated seven key input parameters to construct a comprehensive mathematical representation of the settling process. The proposed explicit model demonstrates superior prediction accuracy compared to existing empirical and drag correlation models. The model’s validity was confirmed using a large and morphologically diverse dataset of 86 irregular materials and rigorously evaluated using an extensive battery of statistical goodness-of-fit parameters. The developed model is a robust and highly accurate tool for predicting the settling behavior of non-spherical particles in the transition flow regime. Beyond its technical merits, the model could offer significant sustainability benefits by enhancing the design and optimization of wastewater treatment systems. More precise predictions of non-spherical particle settling behavior could improve sedimentation or particle removal efficiency, potentially reducing energy consumption and mitigating adverse environmental impacts on industrial waste management and aquatic ecosystem preservation. Full article

Rice is a staple food for global nutrition, and its processing generates large volumes of waste with a consequent environmental impact. The industry needs to improve its capacity to manage and treat this waste with more sustainable options than traditional management methods, thereby mitigating the environmental impact of the rice industry. Among the waste streams generated, rice bran represents a significant fraction that is largely underutilized. This study proposes a comprehensive approach to rice bran recovery, aiming to transform 100% of the waste into bio-based products through a three-stage biorefinery approach that combines chemical and biological operations. The process began with the ethanolic extraction of rice bran, which yielded 20.58% (w·w⁻¹) rice bran oil. This oil, evaluated through both in vitro and in vivo trials, has demonstrated effectiveness when combined with commercial edible coatings, reducing post-harvest damage in grapes and lemons by 15–20%. Following extraction, the remaining defatted rice bran, accounting for 79.42% (w·w⁻¹) of the initial material, was used as a carbon-rich substrate for microbial fermentation by Haloferax mediterranei. This step converts 28.75% (w·w⁻¹) of rice bran into microbial biomass and 12.75% (w·w⁻¹) into polyhydroxybutyrate-valerate. The undigested residual biomass, comprising 37.95% (w·w⁻¹) of the starting material, was further valorized through the purification of high-value products such as cellulose (13.08% (w·w⁻¹)), hemicellulose (14.58% (w·w⁻¹)), and lignin (10.29% (w·w⁻¹)). Overall, the biorefinery model recovers 100% of the initial waste and demonstrates, under laboratory conditions, the model’s ability to transform rice bran into six products of industrial interest, offering an option with the potential to effectively manage rice bran waste and help circularize the production model of an industry that traditionally operates under a linear production model. Full article

Recycled aggregate sourced from construction and demolition waste presents a viable means of reducing the environmental impact associated with concrete production. However, previous research has shown that concrete incorporating recycled aggregate typically exhibits reduced strength and increased susceptibility to deterioration. In this work, eight concrete mixes were prepared using both virgin and locally sourced recycled coarse aggregate from the United Arab Emirates, with selected mixes incorporating various combinations of supplementary cementitious materials (SCMs) (ground granulated blast-furnace slag (GGBS) and silica fume). The mixes were tested over a period of 180 days to evaluate key mechanical properties, durability, and embodied carbon. It was found that partial replacement of Portland cement with GGBS and silica fume had no marked beneficial effect on the strength and water absorption of recycled aggregate concrete when compared to mixes containing virgin aggregate. However, improvements in resistance to chloride ingress and reductions in drying shrinkage were observed. Notably, the incorporation of SCMs resulted in a significant reduction in embodied carbon, with reductions in excess of 40% when compared with conventional Portland cement concrete. Full article

Heat exchangers are key components of advanced waste-heat recovery energy systems that operate on low-boiling working fluids. The efficiency and cost of power plants depend directly on their design characteristics. Increasing the heat-transfer surface area, on the one hand, reduces temperature differences and improves cycle efficiency, but on the other hand increases material consumption and equipment cost. For given fluid parameters and heat-exchanger duty, the required surface area is determined by the type of heat exchanger, the choice of device, the shape of the enhanced heating surface, and the methods of heat-transfer intensification. This paper provides a comprehensive analysis of the current state of heat exchangers for low-boiling working fluids and discusses their areas of application. A methodology has been developed for optimizing the main design characteristics of heat exchangers, including a search algorithm aimed at minimizing the total costs of equipment production and operation. Using this methodology, computational studies were carried out for advanced energy cycles with low-boiling working fluids (organic Rankine cycles, recompression supercritical CO₂ (s-CO₂) Brayton cycle). The relationships of weight, size, and cost parameters of heat exchangers for waste-heat recovery cycles using low-boiling fluids to exhaust-gas temperatures and external economic factors were obtained. Optimal channel geometric parameters and heat-exchanger design types were identified that ensure minimal material consumption and cost while delivering the required heat-transfer performance. Recommendations are formulated for selecting and designing heat exchangers for waste-heat recovery power plants using low-boiling working fluids, the implementation of which will improve their efficiency and reduce costs. Full article

This study employs a practice-oriented research method, emphasizing practical application rather than laboratory testing, and was conducted in Pingtung County, Taiwan, from 2017 to 2023. The practical results of the five case studies demonstrate that (1) eco-friendly buildings integrating agricultural and fishery waste overcome the obstacles of obtaining building permits and (2) the carbon emissions of exterior walls made of pozzolana are only 44% of those of reinforced concrete. This study contributes to understanding the contemporary characteristics of sustainable buildings and provides directly applicable insights into and suggestions on how buildings can actively utilize local materials. Full article

Municipal solid waste (MSW) recycling is constrained by contamination, heterogeneity, and infrastructure built around material-specific pathways. We introduce effectiveness-normalized greenhouse gas (GHG) emissions as a system-level metric that adjusts reported process burdens by feedstock eligibility (Effectiveness Fraction, EF) and carbon recovery efficiency (CRE) to reflect real-world MSW conditions. Using published LCA data and engineering estimates, we benchmark six pathways, mechanical recycling, PET depolymerization, enzymatic depolymerization, pyrolysis, supercritical water gasification (SCWG), and Regenerative Robust Gasification (RRG), at the scale of mixed MSW. Normalizing for EF and CRE reveals large differences between process-level and system-level performance. Mechanical recycling and PET depolymerization show low process intensities yet high normalized impacts because they can treat only a small share of plastics in MSW. SCWG performs well at broader eligibility. RRG, a plasma-assisted molten-bath approach integrated with methanol synthesis, maintains the lowest normalized impact (~1.6 t CO₂e per ton of recycled polymer) while accepting virtually all organics in MSW and vitrifying inorganics. Modeled methanol yields are ~200–300 gal·t⁻¹ without external hydrogen and up to ~800 gal·t⁻¹ with renewable methane reforming. The metric clarifies trade-offs for policy and investment by rewarding technologies that maximize diversion and carbon retention. We discuss how effectiveness-normalized results can be incorporated into LCA practice and Extended Producer Responsibility (EPR) frameworks and outline research needs in techno-economics, regional scalability, hydrogen sourcing, and uncertainty analysis. Findings support aligning infrastructure and procurement with robust, scalable routes that deliver circular manufacturing from heterogeneous MSW. Full article

De-sealing, or depaving, is increasingly adopted to restore soil permeability and support green infrastructure, yet its potential to recover soil functions remains insufficiently understood. This study reports one year of soil monitoring following the de-sealing of a brownfield site in Milan (Italy). It compares the evolution of pedoclimatic parameters in sealed and de-sealed soils and assesses the suitability of recycled aggregates (RAs) from demolition waste as a soil-forming material. Buried sensors continuously recorded pedoclimatic parameters, temperature, water content, and oxygen concentration, while periodic sampling was carried out to analyse soil chemical properties, bacterial community composition, and the quality of percolation water (heavy metal content). De-sealing immediately improved pedoclimatic conditions, enhancing soil aeration, water regulation, and heat exchange capacity. No significant variation was detected in soil chemical properties, apart from pH fluctuations linked to the leaching of alkaline ions from concrete-based RAs. The presence of RAs caused no adverse effects on either soil or percolation water. Bacterial community composition was strongly associated with soil organic carbon, C:N ratio, and soil water content, without showing clear temporal trends. Overall, the study demonstrates that de-sealing rapidly triggers soil functional recovery and that, when properly characterised for composition and contamination risk, RAs pose no evident threat to the surrounding environment. Full article

Background and Objective: Gastric cancer (GC) is a serious public health problem in southeastern Mexico. Some cases go undiagnosed or are diagnosed at advanced stages of the tumors. Borrmann classification is the method used by endoscopists to classify gastric lesions and identify tumor stage. This study aimed to characterize GC patients treated at a specialized hospital in the Yucatan Peninsula, Mexico, according to the Borrmann endoscopic classification, with a focus on clinicopathological characteristics and survival differences. Materials and Methods: A retrospective cohort study was conducted among patients aged 18 years or older who underwent an endoscopic procedure at the hospital to confirm a diagnosis of GC between January 2019 and December 2024. Clinical data were collected, including medical history, blood type, non-communicable diseases, tumor type, tumor location (primary or metastatic), and details of medical and/or surgical treatment. Survival curves were generated for all patients and stratified by the Borrmann classification. Results: A total of 209 cases of GC were included, with 115 men with a mean age of 59.3 years and 94 women with a mean age of 52.2 years. Acid peptic disease (70.3%), followed by wasting syndrome (66.9%), was the most common medical condition in patients with GC. Blood type O with a positive Rh factor was the most frequent (66.5%). According to the Borrmann classification, localized tumors (p = 0.001) were observed at lower Borrmann levels, whereas Helicobacter pylori (p = 0.040) was more frequent at higher levels. The overall survival time was 18 months for all patients; specifically, 18 months at higher Borrmann levels and 20 months at lower levels. Conclusions: GC is a highly prevalent malignancy in southeastern Mexico. The Borrmann classification remains a valuable and practical tool for evaluating GC. The association between Borrmann endoscopic classification and the clinicopathological and survival characteristics may contribute to accurate diagnosis assessment and improved prognostic stratification in future GC cases. Full article

With the rapid increase in solid waste generated worldwide, sustainable approaches for the recovery of resources considering environmental protection are required. As one of the emerging strategies in recent years, biochar has shown great potential due to its high carbon stabilization, adjustable porosity and tunability. This review focuses on the critical assessment of the available technologies for biochar upgrading, with a specific objective of biochar physicochemical functionality improvement and critical materials recovery in line with circular economy targets. We systematically review physicochemical activation methodologies, functionalizations and leaching approaches, accounting for their effects on surface area, porosity and functional group chemistry. Particular attention is paid to the dual functionality of upgraded biochar (i) as a catalyst support for thermochemical processes and (ii) as a medium for the recycling of essential nutrients (e.g., phosphorus, potassium, magnesium, calcium). It is evidenced that customized activation can further improve its adsorption and catalytic efficiency as well as promote near-total nutrition extraction. This review positions advanced biochar as an enabling multipurpose technology across sustainable material production, nutrient cycling and waste valorization in the circular bioeconomy. Full article

The use of wood waste as a component in cementitious composites represents a promising strategy for reducing environmental impact and promoting circular economy principles in the construction sector. This study examines the influence of five types of wood waste, spruce sawdust, spruce shavings, oak, beech, and oriented strand board (OSB), on the properties of Portland cement mortars. A constant 5% by mass of sand was replaced with each wood residue, and mixtures were tested for flowability, density, flexural, and compressive strength at 7, 14, and 28 days. Our results show that wood addition reduces density by 20–36% and compressive strength by 70–85%, depending on species and particle morphology. Denser materials (oak and OSB) resulted in composites with higher mechanical strength, suggesting a more effective particle packing and interfacial interaction compared to porous particles (spruce sawdust, shavings), which led to higher water demand and reduced strength. Beech showed the highest flexural strength, indicating potential for bending-dominated applications. The study demonstrates the feasibility of using selected wood residues for lightweight, non-structural cement composites and outlines the need for future microstructural validation through SEM and porosity analyses Full article

Composite geopolymer concrete (CGPC), is receiving growing attention in the construction sector for its sustainable nature, environmental benefits, and its valuable role in promoting efficient waste utilization. The strategic incorporation of reinforcing fibers into geopolymer concrete (GPC) matrices is critical for enhancing mechanical performance and meeting the durability requirements of high-performance construction applications. Although substantial research has focused on strength enhancement of fiber-reinforced geopolymer concrete (FGPC) individually, it has neglected practical considerations such as energy use for curing and life-cycle assessments. Thus, this study investigates the cost-effective aspects of FGPC cured under different regimes. Different cementitious binders were incorporated, i.e., fly ash (FA) and ground granulated blast-furnace slag (GGBS), in addition to alkaline activators (a combination of sodium hydroxide and sodium silicate), hooked-end steel fibers (HESFs), basalt fibers (BFs), and polypropylene fibers (PPFs), as well as aggregates (gravel and sand). The effect of different geopolymer-based materials, reinforcing fibers, and different curing regimes on the mechanical, durability, and economic performance were analyzed. Results showed that the applied thermal curing regimes (oven curing or steam curing) had a considerable impact on durability performance, compressive strength, and flexural strength development, especially for GPC mixes involving high FA content. Cost analysis outcomes suggested that the most affordable option is GPCM1 (100% FA without fibers), but it demonstrates low strength under ambient curing conditions; RGCM4 (100% GGBS and 0.75% HESF) provided the best strength and durability option but at higher material cost; RGCM7 (50% FA, 50% GGBS, and 0.75% HSF) exhibited a balanced choice since it offer satisfied strength and durability performance with moderate cost compared to other options. Full article

This study investigates the mechanical and durability performance of sustainable concrete using stone dust (SD) and ground sugarcane bagasse ash (GSCBA) to partially replace natural sand and cement, respectively. The experimental program was conducted with concrete containing 0–40 wt% GSCBA and 100% SD were prepared and tested. The results showed that full replacement of natural sand with SD did not significantly affect compressive strength. Concrete containing 10% GSCBA and 100% SD (10GSCBA) exhibited comparable compressive strength to the control concrete (CON) up to 90 days. However, the modulus of elasticity and modulus of rupture decreased slightly with increasing GSCBA content, indicating a close correlation with compressive strength. The mix containing 40% GSCBA and 100% SD (40GSCBA) achieved a compressive strength of 42.6 MPa at 90 days, representing 91% of the CON, with acceptable durability performance. These findings demonstrate that the combined utilization of SD and GSCBA offers an innovative and eco-efficient solution for concrete production, contributing to reduced cement consumption, lower production costs, and minimized carbon emissions without necessarily affecting mechanical strength or the long-term viability of the system. Full article

The limited availability of high-quality ore deposits and the environmental hazards of metallurgical wastes highlight the importance of developing resource-efficient metal recovery technologies. Zinc kiln slag (ZKS), also known as Waelz slag, a by-product material enriched in non-ferrous metals, was processed through oxidative HCl leaching with H₂O₂ as an oxidant. Thermodynamic simulation and laboratory experiments were applied to determine optimal leaching conditions to dissolve copper, zinc, and iron. Optimal leaching efficiency was achieved with consumptions of 0.8 g HCl and 0.1 g H₂O₂ per gram of ZKS, a liquid-to-solid (L/S) ratio of 5 mL/g, a temperature of 70 °C, and a duration of 180 min, which resulted in recoveries of 96.3% Cu, 93.6% Fe, and 76.8% Zn. The solid residue with 43.5 wt.% C is promising for reuse as a reductant material in pyrometallurgical processes. Copper and arsenic were separated from the leachate via cementation with iron powder, achieving recovery rates of 98.9% and 91.2%, respectively. A subsequent two-step iron precipitation produced ferric hydroxide with 52.2 wt.% Fe and low levels of impurities. As a result, the developed novel hydrochloric acid oxidative leaching and metal precipitation route for ZKS recycling provides an efficient and sustainable alternative to conventional treatment methods. Full article

This study adheres to the principles of the circular economy by valorising fruit processing waste—specifically, the oil cake remaining after the cold pressing of plum seeds—for the production of new biopolymer packaging material. This study investigates the effects of incorporating Satureja montana essential oil (SMeo) on the properties of plum oil cake (POC)-based biofilms for potential food packaging applications. The mechanical, physico-chemical, barrier, structural, thermal, and biological properties of the POC-based film were investigated. The results showed that the addition of SMeo had the greatest impact on improving the water vapor barrier permeability (up to 48%). Antimicrobial analyses showed outstanding results against bacteria, yeasts, and molds, with the most pronounced inhibition observed for A. ochraceus and S. aureus. On the other hand, structural analysis confirmed that the 3% SMeo sample underwent the greatest changes, as indicated by the appearance of new bonds originating from oil–biopolymer interactions. This observation was further supported by thermal analysis, which showed that films containing SMeo degraded more rapidly than the control in a dose-dependent manner. The reduction in tensile strength values (up to 35%) suggests that SMeo-loaded POC films are more suitable for use as coatings rather than standalone packaging materials. Full article

Mining activities are conducted to extract valuable minerals from the Earth, which are used to manufacture many objects. However, these operations generate landform alterations, such as deep excavations, artificial embankments, and landscape reshaping. In this study, landform changes were monitored in a mining area in Mazapil, Zacatecas, Mexico, using geomatic techniques. Multitemporal Landsat satellite images and digital elevation models (DEMs) from different years were used to detect and quantify landform alterations and estimate the volumes of removed material. The results show ground depressions greater than −333 m and waste material accumulations greater than +152 m, with an average standard deviation of ±3.6 m. A total excavation volume of 413.524 million m³ and a total fill volume of 431.194 million m³ were quantified, with an estimated standard deviation of ±810 m³. The proposed methodology proved effective for the remote quantification of large-scale relief disturbances in open-pit mining areas. It can also be used for environmental monitoring and hydrological risk assessment in active and inactive mining areas. Full article