Search Results (3,842)

In protracted humanitarian crises, solid waste management (SWM) becomes a major challenge due to limited resources, inadequate infrastructure, and competing response priorities. Waste generated in humanitarian settings typically consist of heterogeneous streams, where plastics, biodegradable fractions, and packaging materials represent the dominant components. Proper management of this waste is essential to reduce health risks and environmental impacts on local communities. Within this framework, sustainable bio-based alternatives and compostable solutions represent promising alternatives. The EU-funded Bio4HUMAN project promotes the integration of innovative bio-based solutions aligned with humanitarian and sustainability goals. An exploratory assessment focused on analyzing waste production, material composition, and handling practices in two case study locations in Sub-Saharan Africa (Democratic Republic of Congo (DRC) and South Sudan (SS)). The results indicate that humanitarian waste cannot be clearly distinguished from household or commercial waste, as streams are typically mixed. Waste composition is dominated by organic matter (43–65%), followed by plastics (15–33%), while other fractions such as paper, glass, metals, and textiles are less significant. Further insights into challenges and opportunities were obtained through a combination of quantitative surveys (n = 29), qualitative interviews with key informants (KIIs) (44) and group discussions sessions (FDG) (9), direct observations, and literature review. Subsequently, a scoping approach was applied to map and classify suitable sustainable solutions into two main categories: bio-based products (BBPs) and organic waste valorization technologies. These were assessed through life cycle assessment (LCA) in accordance with ISO 14040 and 14044, applying SimaPro v.10.2.0.3 software and the Ecoinvent 3.10 database, and compared against fossil-based alternatives. This study compares two case scenarios: a HDPE oil bottle versus PLA alternative (functional unit 6 L), and PE water container versus PLA alternative (functional unit 10 L). For the oil bottle, PLA shows a lower carbon footprint (1.33 kg CO₂-eq) than HDPE (2.37 kg CO₂-eq). In contrast, for the water container, PLA performs worse (2.22 kg CO₂-eq) compared to PE (1.59 kg CO₂-eq), due to higher material demand. The results suggest that benefits are context-dependent and most evident for lightweight products with high leakage risks, particularly when composting infrastructure is accessible. This study advances previous work on humanitarian SWM by integrating field-based waste flow characterization with context-specific screening and life cycle assessment of bio-based alternatives, providing quantitative evidence on the conditions under which these solutions can effectively reduce environmental burdens in protracted crisis settings. Full article

Prolonged cultivation of cereal-based cropping systems in the Indo-Gangetic Plain has contributed to soil degradation, groundwater depletion, and declining soil organic carbon levels, highlighting the urgent need for climate-resilient, sustainable crop diversification strategies that enhance soil carbon sequestration and improve overall soil health. A 6-year field experiment assessed 10 cropping systems (CSs) using a randomized complete block design with four replications, focusing on their effects on soil carbon stocks and sequestration at two soil depths (0–15 cm and 15–30 cm). It was inferred from the results that there is a significant variation in soil carbon stocks, with maize–peas–spring groundnut (CS6) having the highest surface carbon stock (13.0 Mg ha⁻¹) and baby corn–potato–okra (CS10) having the highest sub-surface carbon stock (11.9 Mg ha⁻¹). Carbon sequestration peaked in CS6 at 5.06 Mg ha⁻¹ at 0–15 cm, and its sequestration rate was the highest (0.84 Mg ha⁻¹ yr⁻¹). Total organic carbon (TOC) ranged from 0.63% in Rice–Wheat (CS1) to 0.73% in CS6, with similarly high values in other diversified systems. Very labile carbon (VLC) was highest in basmati rice, late-sown wheat, and cowpea (CS3) and CS6, demonstrating the benefits of legume-based systems. At depths of 15–30 cm, trends were consistent but lower. Water-soluble carbon (WSC) and hot water-soluble carbon (HWSC) showed significant differences across systems, with CS3 recording the highest values. The findings indicate that cropping systems incorporating legume diversification and green manuring enhance carbon stocks, sequestration rates, and soil carbon stability, demonstrating that crop diversification is an effective means of increasing soil carbon storage, promoting soil health, and supporting sustainable agricultural production in Northwestern India. Full article

Methane (CH₄) was employed as a carbon source for the reduction and carburization of TiO₂ via a gas-phase infiltration process to synthesize titanium carbide (TiC). The highly reactive and diffusible carbon species derived from CH₄ decomposition enable a significant reduction in both reaction time and temperature compared with conventional carbothermal reduction methods. The phase evolution during the CH₄-driven reduction–carburization of TiO₂ was analyzed, and the effects of CH₄ volume fraction, reaction temperature, and reaction time on the carburization efficiency were systematically investigated, with the phase composition and microstructure of the products also characterized. The optimal conditions in a CH₄-Ar system were found to be 10%CH₄–90%Ar at 1270 °C for 8 h, yielding a carburization efficiency of 79.1% for TiO₂ pellets. Increasing the CH₄ proportion led to more severe carbon deposition, with deposited carbon adhering to the pellet surface and clogging the internal pores. Raising the temperature promoted the reduction–carburization reaction, but excessive acceleration of CH₄ cracking above 1270 °C caused carbon accumulation on the TiO₂ surface, forming a carbon shell that lowered the carburization efficiency. Prolonging the reaction time was beneficial for achieving a higher degree of carburization. Full article

While geotechnical parameter determination is fundamental to foundation engineering, traditional approaches often suffer from data fragmentation and subjective safety assessments. This research introduces an integrated framework that synthesizes multivariable regression with the Effective Random Dimension (ERD) method to bridge the gap between raw laboratory indices and structural design. By analyzing datasets from the stable Suceava Moldavian Platform (68 samples) and the tectonized Subcarpathian Flysch (50 samples), the study demonstrates that granulometric fractions, moisture content, and carbonate content can predict consistency limits with high statistical fidelity, achieving R² = 0.98 for the Liquid Limit at Suceava and R² ≈ 0.90 for the Plasticity Index at Doftana. The novelty of the approach lies in the generation of continuous vertical profiles transformed into code-compliant characteristic values (X_k) via Taylor series linearization and the ERD framework. The derived characteristic interval for the Plasticity Index (58.66–70.15%) quantitatively demonstrates the reduction in hyper-conservative bias compared with discrete sampling. This methodology eliminates subjective judgment and ensures a mathematically rigorous transition to Eurocode 7 and NP 122:2010 standards, optimizing both safety and economic efficiency in variable geological strata. Full article

The present study investigates the possibility of selective iron reduction from the Keregetas iron–manganese ore deposit (Kazakhstan) using hydrogen, followed by the separation of iron- and manganese-containing phases. The relevance of the research is associated with the need to develop environmentally sustainable processing technologies for low-grade iron–manganese ores under the conditions of metallurgical industry decarbonization. Experimental studies were carried out at temperatures of 800–900 °C in a high-purity hydrogen atmosphere, followed by magnetic separation and liquid-phase separation of the reduction products. The phase and chemical compositions of the samples were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). It was established that during the reduction process, iron oxides were predominantly transformed into the metallic state with the formation of α-Fe, whereas manganese oxides were mainly reduced to MnO and Mn₃O₄. Magnetic separation demonstrated limited selectivity due to the simultaneous transfer of iron-containing and manganese-containing phases into the magnetic fraction. At the same time, liquid-phase separation of the pre-reduced material at 1650 °C ensured effective separation of metallic and slag phases, with manganese concentrated in the slag and minimal losses in the metallic product. A technological flowsheet for the processing of iron–manganese ores is proposed, including hydrogen reduction, magnetic separation, and subsequent high-temperature phase separation. The obtained results demonstrate the prospects of hydrogen metallurgy for the development of low-carbon technologies for the integrated processing of iron–manganese raw materials. Full article

Fresh flotation tailings represent an underutilized archive of mineralogical and geochemical information in which multiple strands of evidence for ore-forming processes and post-depositional modification can be preserved. Detailed characterization of tailings is also vital for assessment of their future potential as a secondary source of recoverable by-products. This study investigates residual mineral speciation and mineral distributions in size fractions of tailings from the Prominent Hill iron oxide–copper–gold (IOCG) deposit, South Australia, with emphasis on rare earth element (REE) minerals and associated phases containing uranium (U). Assemblages of REE minerals can be highly complex at the micron scale and include sequences of mineral replacement, notably monazite → florencite, and monazite → synchysite. Bastnäsite-(Ce) commonly appears paragenetically early and is frequently altered or replaced by synchysite and parisite, supporting episodes of REE remobilization and reconcentration over geological time. Uranium is closely associated with REEs, and U-mineral assemblages are similarly characterized by intricate replacement relationships between uraninite and secondary phases. Uraninite is variably replaced by coffinite and the U-carbonate wyartite, reflecting changes in redox state, silica activity, and fluid composition. Additional replacement pathways from uraninite to Cu–Fe sulphides, including bornite and chalcopyrite, are documented and indicate coupled dissolution–reprecipitation of sulphides and U-minerals during superimposed hydrothermal activity. Preservation of mineralogical relationships within tailings drawn from multiple parts of a large deposit highlights their value as an essentially untapped library of information to reconstruct deposit evolution, complementing traditional study of selected drill core samples. Systematic investigation of tailings from large deposits can improve genetic models for large copper deposits, including but not restricted to IOCGs, and provide essential insights into REE behaviour, uranium remobilization, and critical metal potential. These findings emphasize the scientific and economic value of tailings-based studies for improved resource characterization, refining metallogenic interpretations, guiding future exploration strategies, and assessing opportunities for reprocessing and metal recovery in large ore systems worldwide across diverse geological settings. Full article

Urbanisation-driven housing demand and the environmental burden of sewage sludge disposal highlight the need for low-carbon, circular construction materials. This study evaluates incinerated sanitary sludge ash (ISSA) as a supplementary cementitious material in stabilised earth blocks, aiming to reduce the use of cement and lime while valorising waste sludge. Lateritic soil blocks were produced with a binder-to-soil ratio of 1:7 by mass, in which ISSA partially replaced the primary stabilising binder (cement or lime) at a replacement level of 10–40% within the binder fraction. ISSA’s mineralogical characteristics were analysed using XRD and XRF. The compressive strength and density of earth blocks were measured at 7 and 28 days under curing conditions (29–36 °C; 60–75% humidity). Cement-stabilised blocks were water-cured to support cement hydration, whereas lime-stabilised blocks were air-cured to promote carbonation and pozzolanic reactions. The results, therefore, compared practical binder-specific curing regimes rather than strictly identical curing environments. ISSA exhibited moderate pozzolanic potential, and its incorporation enabled substantial partial replacement of both binders. Cement-stabilised blocks achieved higher strengths, up to 7.7 MPa, after 28 days of curing, whereas lime-stabilised blocks developed strength more gradually, reaching 4.8 MPa. Optimal mixtures were identified at 40% cement + 60% ISSA and 30% lime + 70% ISSA, balancing mechanical performance and binder reduction. A positive density–strength relationship was observed, but chemical bonding predominated over densification effects. ISSA-based stabilised earth blocks show promising structural performance and reduced binder use, but durability and life-cycle assessment need further evaluation before large-scale implementation. Full article

Waste lubricating oils (WLOs) represent a major stream of hazardous petroleum-based residues, with global generation exceeding 24 million tons annually. Improper disposal of WLOs poses risks to soil, water, and air quality, while their chemical composition makes them a potential secondary resource within circular economy frameworks. This review summarizes conventional, advanced, and emerging technologies reported for the recycling and valorization of WLOs into high-value petrochemicals and carbon-based materials. Established processes such as acid–clay treatment, solvent extraction, and vacuum distillation are discussed together with more recent approaches, including catalytic upgrading, hydrotreatment, membrane separation, and thermochemical conversion methods such as pyrolysis and catalytic cracking. Reported data on process performance, environmental considerations, techno-economic indicators, and life cycle assessment outcomes are comparatively analyzed to outline current trends, technical challenges, and future development directions in WLO recycling. Particular attention is given to thermochemical pathways capable of generating carbonaceous materials, including carbon black, porous carbons, and functional carbon nanostructures with potential applications in adsorption, catalysis, electrochemical systems, and tribological formulations. Hybrid and integrated process configurations described in the literature are highlighted for their potential to improve recovery efficiency, enhance product quality, and reduce environmental burdens. In addition, recent life cycle assessment (LCA) and techno-economic analysis (TEA) studies are reviewed to provide insight into the environmental and economic implications of advanced re-refining systems. Overall, the reviewed literature indicates that WLO recycling represents not only an important element of sustainable lubricant management but also a promising waste-to-carbon strategy for the production of value-added carbon-based materials and petrochemical products. Full article

Among pathways toward carbon neutrality, substituting hydrocarbons with hydrogen-carrier fuels such as ammonia presents significant potential for carbon emission reduction. This study examines the combustion characteristics of ammonia (NH₃) and simulated LPG consisting of 70% propane (C₃H₈) and 30% butane (C₄H₁₀) by volume blends under non-premixed conditions using a crossflow slot burner. Flame appearance, OH* chemiluminescence, flame temperature, and CO and NO_x emissions were evaluated at equivalence ratios (Φ) of 0.4, 0.7, and 1.0, with ammonia fractions ranging from 0% to 70%. Increasing ammonia content decreased OH* chemiluminescence intensity, indicating a reduced radical pool and lower reaction intensity, particularly under lean conditions. Nevertheless, stable combustion was achieved at Φ = 1.0 due to improved mixing and heat recirculation. Flame temperature declined by only 9.3%, even at 70% ammonia, confirming good thermal stability. NO_x emissions exhibited non-monotonic behavior, increasing at moderate ammonia fractions due to fuel-bound nitrogen and thermal mechanisms, and then decreasing at higher ammonia levels as flame temperature and radical activity diminished, while CO emissions remained low up to 50% ammonia near stoichiometric conditions but increased under ultra-lean operation because of limited oxidation kinetics. These results highlight the feasibility of simulated LPG–NH₃ blends as transitional low-carbon fuels in practical combustion systems. Full article

The blast furnace–basic oxygen furnace long process is the dominant steel production route in China. Increasing the scrap ratio is an effective way to reduce cost and carbon emissions, and scrap preheating is a key technology to achieve a high scrap ratio. To improve the low thermal efficiency and poor deep-bed melting performance of converter gas-based scrap preheating, an innovative process using oxygen-enriched combustion in a hot metal ladle is proposed. Numerical simulation is essential for capturing the complex multiphysics phenomena, as real-time monitoring of melting inside the packed scrap bed is extremely difficult. In this study, a novel multiphysics approach based on a User-Defined Function (UDF) is developed to dynamically track the progressive melting of the scrap skeleton, overcoming the key limitation of conventional enthalpy–porosity models that cannot capture the feedback between phase change and porous medium property evolution. A three-dimensional transient model was established, integrating turbulent combustion, gas–solid convective heat transfer in porous media, and solid–liquid phase change. The effects of impact pit depth, scrap porosity, and converter gas flow rate on temperature distribution, melting behavior, and thermal efficiency were systematically investigated. Results showed that porosity had the strongest influence; thermal efficiency increased from 33.92% to 65.59% as porosity rose from 0.6 to 0.8, due to a transition from conduction-dominated to coupled convection–conduction heat transfer. Converter gas flow rate exhibited a non-monotonic effect, peaking at 3688.14 m³·h⁻¹, highlighting a trade-off between energy input and gas residence time, while impact pit depth showed a limited effect with diminishing returns. A 600 s full-process simulation revealed stage-dependent melting, and the initial phase was crucial for process optimization. The optimal condition, with a pit depth of 64 cm, porosity of 0.8, and converter gas flow rate of 3688.14 m³·h⁻¹, achieved a 1.23% melting fraction and 65.59% thermal efficiency within 120 s. These findings clarify the combined roles of geometric confinement, permeability, and energy-residence time interactions, providing guidance for industrial scrap preheating design. Full article

Biomineralization in plant tissues is a widespread process accompanied by carbon fixation in biogenic minerals. This study aimed to evaluate the effect of CaCO₃ application to soil on the formation and localization of biominerals in the pericarp of fruits of Buglossoides arvensis (L.) I.M. Johnst., as well as on the accumulation of carbon in minerals. B. arvensis seeds were sown in the soil treated with CaCO₃ at concentrations of 0.0 (0 Ca), 2.5 (2.5 Ca), 5.0 (5 Ca), 7.5 (7.5 Ca), and 10.0 (10 Ca) t ha⁻¹. As a result of CaCO₃ application, on average across all treatments, the increase in soil pH was 30%, and the calcium and silicon content in the soil increased by 60 and 39%, respectively. The fruit weight was 4, 28, 42, and 21% higher in 2.5 Ca, 5 Ca, 7.5 Ca, and 10 Ca plants than in 0 Ca plants. Scanning electron microscopy analysis revealed the presence of silica and calcium carbonate in the pericarp of B. arvensis fruits, but showed no significant differences in the localization of biominerals in the pericarps between the treatments. The content of biosilica (phytoliths) was lower in 2.5 Ca, 5 Ca, 7.5 Ca, and 10 Ca plants than in 0 Ca plants, respectively, by 11, 14, 25, and 19%. The content of organic carbon occluded in a unit mass of phytoliths was, on average, 49% higher in treated than in 0 Ca plants. The content of carbonate fraction in fruits was 13, 14, 20, and 21% higher in 2.5 Ca, 5 Ca, 7.5 Ca, and 10 Ca plants than in 0 Ca plants, reflecting the effect of soil calcium levels on carbonate content in B. arvensis pericarp. Thus, in the pericarp of fruits, the ratio of silica to carbonates changed towards a decrease in silica content and an increase in carbonate content as the availability of calcium in the soil increased. In summary, B. arvensis responds to increased soil calcium and soil pH by increasing carbon accumulation in biominerals formed in fruit pericarps, supporting the potential for variability in plant biomineralization characteristics under changing growth conditions. Full article

The integration of biochar into asphalt binders represents a significant advancement toward global sustainability in pavement engineering. Produced through biomass pyrolysis, biochar enables the valorization of agricultural and industrial waste while reducing dependence on petroleum-derived binder constituents. This review critically synthesizes current research regarding the impact of biochar on the physical, rheological, and aging performance of bitumen. The evidence consistently shows that biochar improves binder stiffness, raises softening points, and strengthens rutting resistance at elevated temperatures, largely due to its porous microstructure and high carbon content. Biochar-modified binders also exhibit enhanced aging resistance through the adsorption of volatile light fractions. These improvements are primarily ascribed to the carbonaceous composition and high porosity of the biochar particles. However, systemic challenges, including phase stability at high concentrations, long-term oxidative aging, and a lack of standardized characterization protocols, hinder widespread implementation. By identifying consistent findings, contradictions, and critical research gaps across the literature, this review provides a consolidated foundation to guide the transition of biochar-modified bitumen from laboratory investigation to large-scale pavement infrastructure applications. Full article

Road infrastructure accounts for a substantial and systematically under-reported fraction of construction-related embodied carbon globally. Despite rapid network expansion across sub-Saharan Africa, no peer-reviewed study identified in the databases searched has established a quantified embodied-carbon baseline for Ghanaian road construction, creating a notable gap in national carbon accounting and low-carbon procurement policy. This study addresses that gap through two integrated components: a PRISMA 2020-guided systematic review of road-LCA and embodied-carbon literature, and a first-pass scenario model for Ghanaian low-volume paved roads (LVRs) bounded at A1–A3 (cradle-to-gate). Database searches of Scopus and Web of Science (14 March 2026) returned 3193 records; following deduplication and two-stage screening, 574 studies were included in the review. A staged harmonisation procedure converted 211 benchmark-shortlisted studies to comparable units, yielding a harmonisation subset of 29 studies and a final benchmark pool of 10 studies expressed as kgCO₂e per lane-kilometre (3.5 m lane width). The scenario model applies emission factors from the ICE Database (Educational V4.1, 2025) to three pavement configurations drawn from the Ghana Manual for Low Volume Roads (Parts B and D), all surfaced with double bituminous surface treatment (DBST); Otta seal is evaluated as a sensitivity case. Results show A1–A3 embodied carbon of 14,165 kgCO₂e/lane-km for Scenarios S1 and S3 (SC2/TLC 0.01 and SC4/TLC 1.0, respectively) and 12,564 kgCO₂e/lane-km for Scenario S2 (SC3/TLC 0.3). Bituminous binder accounts for 30–34% of A1–A3 emissions despite representing less than 1% of pavement mass, identifying binder supply as the primary carbon lever. The two most structurally comparable benchmark studies, chip-seal treatments in the USA, bracket the Ghana values at 12,687–16,400 kgCO₂e/lane-km, providing external plausibility validation. To the best of our knowledge, this study delivers a peer-reviewed, reproducible A1–A3 (cradle-to-gate) carbon baseline for Ghanaian LVR construction, a PRISMA-compliant synthesis of road embodied-carbon evidence, and a documented framework for early-stage carbon benchmarking in West African road infrastructure planning. Full article

This study investigates the feasibility of recycling scallop shells as a partial substitute for natural coarse aggregates in concrete at replacement rates of 20%, 30%, and 40% by mass. The originality of the work lies in combining conventional mechanical and durability tests with a six-month environmental monitoring protocol under simulated rainfall and an end-of-life regulatory interpretation of chemical release. Processed shells were used as a 2/20 mm coarse fraction and characterized by a density of 2713 kg/m³, a water absorption of 2.93%, and a Los Angeles coefficient of 15.1. At 28 days, compressive strength decreased from 33.7 MPa for the reference concrete to 27.9 MPa, 28.1 MPa, and 26.7 MPa for SS20, SS30, and SS40, respectively. Water-accessible porosity increased from 7.8% to 9.9%, and carbonation depth after 70 days increased from 6.2 mm to 12.8 mm at 40% shell replacement. In contrast, chloride ion migration decreased from 19.0 × 10⁻¹² m²/s for the reference concrete to 17.4, 16.3, and 12.1 × 10⁻¹² m²/s at 90 days for SS20, SS30, and SS40, respectively. Environmental monitoring showed low runoff concentrations for anions and trace metals, all below the French regulatory thresholds considered in this work. Under the conditions of this study, shell replacement up to 30% appears technically feasible for non-structural or lightly loaded applications, while the environmental behavior remained compatible with an inert end-of-life classification. Full article

Carbon nanotube (CNT)-reinforced composites are promising advanced materials due to their exceptional mechanical properties. This paper presents a comprehensive investigation of the mechanical behavior of CNT/epoxy composites through theoretical modeling and experimental validation. An equivalent cylindrical fiber model was developed to transform CNTs into effective reinforcement phases, enabling the application of classical composite mechanics. Three reinforcement configurations were analyzed: two unidirectional short fiber models (aligned and staggered) and a three-dimensional four-directional braided long-fiber model. The effects of geometric parameters, including the diameter-to-thickness ratio (D/t) and fiber aspect ratio, on the effective elastic moduli were systematically evaluated. Static and dynamic compression experiments were conducted using an MTS 810 testing system and a Split Hopkinson Pressure Bar (SHPB) to examine the influence of loading rate, vacuum treatment, and reinforcement type (CNT, SiC, and hybrid SiC/CNT) on composite strength. The results indicated that 3 wt% CNT reinforcement increases the Young’s modulus by 30% under static loading and enhanced the dynamic compressive strength under impact loading. The vacuum degassing process significantly affected composite quality, with insufficient vacuum leading to strength degradation due to void formation. Theoretical predictions using Mori–Tanaka and dilute methods showed good agreement with experimental results at low reinforcement volume fractions. Scanning electron microscopy revealed uniform CNT dispersion and provided insights into failure mechanisms, including CNT pull-out and breakage. This work contributes to the understanding of structure–property relationships in CNT-reinforced polymer composites and provides guidelines for achieving their optimal design. Full article