Search Results (5,475)

The world’s food industry faces significant obstacles today as it strives to meet the nutritional needs of its rapidly expanding global population while also managing an immense amount of food processing waste (FPW) generated throughout the entire food supply chain. The widespread use of traditional disposal techniques for food waste (landfilling and incineration) regularly faces challenges related to environmental sustainability and economic efficiency. This manuscript reviews the necessary transition from a linear “take-make-dispose” approach to food production to a more circular model that recycles food waste into high-value intermediate chemicals and renewable energy through the development of biorefineries. The manuscript explores the biochemical composition of food waste, with carbohydrates, lipids, proteins, and bioactive materials, making it a suitable feedstock for different multi-stage biorefinery operations. In addition, this review will evaluate a variety of existing conversion technologies for food processing waste, such as biological methods (e.g., anaerobic digestion and fermentation) and thermochemical methods (e.g., pyrolysis, gasification, and hydrothermal liquefaction), to create various platform chemicals, including organic acids, bio-alcohols and volatile fatty acids (VFAs), as well as the production of sustainable biofuels and biopolymers. The review also elucidates the three most determinative constraints on large-scale industrial implementation of food waste valorisation: feedstock variability, techno-economic feasibility, and the need for comprehensive life cycle assessments (LCAs). The alignment of food waste management strategies with the UN SDGs (in particular, SDG 12 ‘Responsible Consumption and Production’ and SDG 13 ‘Climate Action’) reflects the opportunity for food waste to serve as a foundation for a carbon-neutral, sustainable future. This review provides a strategic roadmap for academics, practitioners, and policymakers to tap into the full potential of food waste through a sustainable circular economy model. Full article

The growing interest in sustainable materials has stimulated research into bio-based reinforcements. This study investigates the influence of fiber extraction methods on the properties of Carica papaya (CP) pseudostem fibers and on the performance of polyester-based nonwoven composites. Fibers were extracted by water retting (CPFR) and alkaline treatments using 5 wt.% NaOH (CPF5) and 10 wt.% NaOH (CPF10). Preliminary characterization confirmed the suitability of CP fibers as reinforcements for nonwoven composite materials. After carding, the fiber mats were impregnated with unsaturated polyester resin (UP), consolidated by compression molding, and post-cured in an oven. The experimental results showed that alkaline extraction significantly improved fiber–matrix adhesion and reduced water uptake. CPF10UP exhibited the lowest porosity (12.7%) and water absorption (2.62%). CPF5UP provided the best overall mechanical performance, achieving the highest tensile and flexural properties compared with neat polyester resin. In contrast, CPF10UP maximized tensile stiffness, impact resistance, and thermal stability. Radar chart analysis revealed two distinct optimization strategies: CPF5UP for superior mechanical performance and CPF10UP for enhanced moisture resistance and impact durability. Overall, the 5 wt.% NaOH treatment provided the best compromise between strength and stiffness, whereas the 10 wt.% NaOH treatment favored higher rigidity, thermal stability, and water resistance. Derived from agricultural waste, CP fibers demonstrate strong potential for semi-structural automotive interior components, particularly door panels, while supporting circular economy principles and sustainable material development. Full article

This study investigates the hydrometallurgical recovery of valuable metals from copper shaft furnace dust (SFD), a complex industrial waste containing approximately 40 wt.% Zn, 16 wt.% Pb, and 1 wt.% Cu. In contrast to conventional inorganic leaching processes that rely on aggressive acids and bases, this research explores the use of deep eutectic solvents (DESs) as eco-friendly and selective lixiviants. Deep eutectic solvents based on choline chloride combined with citric acid and lactic acid were evaluated as leaching media for metal recovery from SFD. The effects of temperature, leaching time, stirring intensity, and the DES:SFD ratio on metal extraction were systematically investigated. Analytical characterization of the raw material, leaching residues, and pregnant leach solutions was performed using Atomic Absorption Spectroscopy (AAS), X-ray Fluorescence Spectrometry (XRF), and Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy (SEM–EDS). The experimental results demonstrated efficient recovery of Zn, Pb, Cu, and Sn under mild leaching conditions. For the citric acid–choline chloride system, the highest extraction efficiency was obtained at 60 °C using a DES:SFD ratio of 30, whereas increasing the temperature to 70–80 °C did not significantly improve metal extraction. The lactic acid–choline chloride system exhibited different leaching behaviour, with the highest recoveries achieved after short leaching times. These findings indicate that DES-based systems represent a promising, sustainable alternative for the selective leaching of heavy metals such as Zn, Pb, Cu, and Sn, from metallurgical secondary raw materials, contributing to the development of greener circular economy practices. Full article

This paper explores the technical, economic, and environmental viability of producing secondary wrought aluminium alloys from post-consumer scrap. The technical review relates to the industrial-level use of laser-induced breakdown spectroscopy (LIBS) in automated scrap sorting under realistic operating conditions. First, process scrap was used to determine the accuracy of LIBS in sorting and separating wrought aluminium alloys, and then the method was applied to post-consumer scrap streams. The melted products were then analyzed, and their chemical compositions were confirmed using optical emission spectroscopy (OES) to meet the established alloy specifications. The economic analysis compares traditional recycling routes of cast alloys with a second route in which recyclers provide already sorted secondary wrought alloys, with a focus on cost and market feasibility. Simultaneously, an environmental analysis using life cycle analysis (LCA) measures the effects of sorting and manufacturing procedures. The results show that LIBS can effectively sort secondary wrought aluminium under controlled input conditions. The process reaches a break-even point in about five years when a 50% price premium for secondary wrought alloys over mixed scrap is assumed. The method is environmentally beneficial, with the global warming potential per kilogram of aluminium reduced by over 95% compared to the global average. The findings highlight the significant potential of combining advanced sorting technologies, new business models, and sustainability-oriented practices to support the implementation of circular material flows in aluminium recycling. Full article

Metal–organic frameworks (MOFs) have emerged as a versatile class of porous nanomaterials with exceptional surface area, tunable pore architectures, and customizable chemical functionalities, creating new opportunities for advanced food applications. Increasing demand for functional foods, precision fermentation, and sustainable bioprocessing has stimulated interest in MOFs as multifunctional platforms for microbial encapsulation, biocatalyst stabilization, and resource recovery. This review examines recent advances in the design and application of MOFs for probiotic delivery, precision fermentation, and circular food systems. The relationships between MOF structure, physicochemical properties, and functional performance are discussed in the context of probiotic encapsulation, protection against environmental and gastrointestinal stress, and controlled release within the intestinal tract. Emerging applications in precision fermentation are evaluated, including microbial immobilization, enzyme stabilization, metabolite separation, and bioprocess intensification. The potential of MOFs to enable circular food systems through the valorization of fermentation by-products, nutrient recovery, and waste-to-value strategies is also assessed. Despite significant progress, challenges related to biocompatibility, food-grade synthesis, scalability, regulatory approval, and long-term safety continue to limit industrial implementation. Future research directions include the development of sustainable and biodegradable MOFs, data-driven material design, and standardized evaluation frameworks to accelerate the translation of MOF-enabled technologies from laboratory research to commercial food applications. Full article

Although low-carbon geopolymers incorporating construction and demolition waste (CDW) offer a promising circular economy pathway, the synergistic mechanisms between pretreated recycled fine aggregates (RFA) and geopolymer binders have not been systematically elucidated. This study investigated the comprehensive performance of geopolymer mortar containing recycled powder (RP) incorporating RFA; 50% Fly ash, 25% slag, and 25% RP were incorporated as precursor for the production of geopolymer binders, while the replacement ratios (0%, 20%, 40%, 60%, 80%, 100%) and the pretreatment methods (carbonation and prewetting) of RFA were taken as experimental parameters. The effect of these parameters on the fluidity, setting time, water absorption, compressive strength, and microstructure of recycled geopolymer mortar (RGM) and recycled cement mortar (RCM) was analyzed. Results showed that as the RFA replacement ratio increases, the measured properties generally decline. However, pretreating the RFA, particularly through carbonation, effectively mitigates these drawbacks. The use of 60% carbonated RFA enhanced the compressive strength of RGM by 12% compared to untreated RFA at equivalent replacement ratio. A comparative evaluation of the performance variations between RGM and RCM revealed that geopolymer mortar exhibited lower fluidity, faster setting time, and higher compressive strength. The microstructure analysis by SEM showed that the geopolymerization reaction between adherent cement paste in RFA and geopolymer binders significantly enhanced the microstructural compactness compared to RCM. Furthermore, carbonation and prewetting treatments can mitigate cracks and pores in the mortar. The results demonstrate that RGM prepared with carbonated RFA offer an estimated 76% reduction in net CO₂ emission and 14.3% reduction in total cost relative to conventional cement mortar. This study established a framework that compares the mechanisms of RFA pretreatment and equip engineers with validated pretreatment strategies for upcycling CDW into construction materials. Full article

The building industry is central to climate change mitigation because it generates substantial energy use and carbon emissions across the full building life-cycle, from material production to operation. Passive and energy-efficient designs, renewable energy integration, use of low-carbon and reusable materials, digital optimization, and circular waste management can minimize operational and embodied emissions, and climate-responsive design can enhance heat, water stress, and other environmental resilience. This study explores sustainable construction practices and climate change mitigation strategies in four different economies: China, Malaysia, South Africa, and Peru. Based on questionnaire data collected from professional engineering and green building networks associated with the World Federation of Engineering Organizations (WFEO), the study applies thematic analysis to compare national priorities and strategies. The findings show that each country pursues sustainability according to its resources, development needs, environmental challenges, and technological strengths. China and Malaysia emphasize energy-efficient design and digital building systems, South Africa focuses on climate-responsive design and material recovery, while Peru prioritizes bio-based materials and local solutions. Overall, renewable energy, circularity, resource optimization, and digital technologies emerge as key trends in advancing low-carbon, climate-resilient construction. Full article

The growing demand for rare earth elements (REEs), heavy metals (HMs) and precious metals (PMs) has intensified interest in sustainable recovery strategies from secondary resources, including mining residues, industrial effluents and waste electrical and electronic equipment (WEEE). These streams represent exposure interfaces, because soluble and bioavailable metal species may persist, bioaccumulate and contribute to oxidative stress, genotoxicity, carcinogenic outcomes and chronic systemic effects. This systematic review, conducted following PRISMA guidelines, evaluates the thermoacidophilic red microalga Galdieria spp. as an extremophilic platform for metal bioremediation, recovery and upstream risk reduction. Galdieria spp. combines tolerance to low pH, elevated temperature and high metal loads with rapid surface biosorption and, in living biomass, slower intracellular sequestration and detoxification. Its interaction with REEs, PMs and toxic HMs is mediated by cell-wall functional groups, extracellular polymeric substances, redox-active processes and metabolic flexibility shaped partly by horizontal gene transfer (HGT). The review discusses matrix complexity and adsorption–desorption cycles, highlighting their implications for real industrial streams. Overall, Galdieria spp. emerges as a robust extremophilic bio-interface for selective metal recovery, hazardous waste mitigation, circular-economy biorefinery models and prevention of metal-associated risks to environmental and human health, while current scale-up limitations and process-oriented research priorities are identified. Full article

The increasing demand for sustainable road infrastructure has encouraged the development of asphalt mixtures incorporating recycled materials and industrial by-products. This study developed and validated a highly circular AC14 asphalt surface mixture incorporating steel slag aggregates (SSA) and reclaimed asphalt pavement (RAP). The laboratory-designed mixture contained 63.8% SSA and 17.2% RAP, corresponding to 81.0% secondary materials, or 83.0% when recovered filler is included. Its volumetric and mechanical performance was compared with that of a conventional AC14 surface mixture with natural aggregates. The highly circular formulation was then produced in an asphalt plant and applied in a full-scale field trial. A life cycle assessment (LCA), following EN 15804:2012+A2:2019, and a production-stage cost analysis were conducted using plant-specific data. The highly circular mixture showed improved rutting resistance, higher stiffness modulus, very high resistance to water damage, and better fatigue indicators than the conventional reference mixture. The field trial supported its feasibility under real production and construction conditions. The LCA showed reductions in 12 of the 13 product-stage environmental impact indicators, including reductions of 18.1% in total global warming potential, 26.6% in abiotic depletion potential for fossil resources, 77.6% in abiotic depletion potential for minerals and metals, and 81.5% in water deprivation potential. The estimated production-stage unit price was 36.4% lower than that of the conventional mixture and 45.4% lower than the Portuguese market benchmark. These results demonstrate the technical, environmental, and economic potential of highly circular asphalt surface mixtures incorporating SSA and RAP. Full article

This study assesses the technical performance and environmental impact of traditional and eco-efficient materials used in civil construction in Colombia through a structured synthesis of scientific, technical, and regulatory evidence covering the period 2010–2025. The analysis integrates mechanical performance indicators, environmental footprint metrics, and the national regulatory framework supporting sustainable material adoption. Results show that conventional materials—Portland cement, structural steel, ceramic bricks, and timber—remain essential due to their proven structural reliability but are also responsible for the highest contributions to CO₂ emissions, energy consumption, and resource depletion. In contrast, eco-efficient alternatives, including blended concretes with mineral additions, geopolymers, rammed earth, Guadua angustifolia, and natural biocomposites, achieve carbon emission reductions between 40% and 85% while maintaining comparable mechanical performance for specific applications. Colombian policies—notably Resolutions 1257 of 2021 and 0194 of 2025—promote waste valorization and low-impact materials, yet their implementation remains limited by technical, economic, and knowledge barriers. The findings support a decision-oriented framework for material selection that balances structural efficiency with environmental responsibility. Full article

The growing demand for granular materials in transportation infrastructure increases the extraction of natural aggregates and the environmental impacts of the construction sector. At the same time, large volumes of municipal solid waste incineration bottom ash (IBA) and mine tailings (MTs) are generated and stored, posing environmental and geotechnical challenges. This review critically evaluates the potential of these waste streams as alternative materials for transportation infrastructure embankments, including zoned embankment approaches, that may enhance sustainability. The analysis integrates evidence on physical, geotechnical, and environmental performance, including compaction, compressibility, shear strength, permeability, bearing capacity, chemical composition, leaching, and ecotoxicity. IBA generally exhibits favourable engineering properties, although its performance depends on ageing and pre-treatment. MTs show greater variability, with behaviour largely controlled by mineralogy, particle-size distribution, and contaminant mobilisation potential. Environmental assessment should consider total chemical composition alongside leaching behaviour, ecotoxicity, and exposure conditions. Overall, the safe use of IBA and MTs requires an integrated evaluation of geotechnical and environmental performance, enabling their selective placement within functional embankment zones. Such approaches can support circular resource use and more sustainable transportation infrastructure without compromising technical performance. Full article

Earthen plasters are attracting interest as low-impact, vapour-open finishing systems, yet most evidence still derives from laboratory characterization rather than from full-scale exposure. Their application in real buildings is still constrained by regulatory and material-related barriers, as national regulatory frameworks remain uneven and existing guidelines provide limited support for fibre-reinforced earthen mixtures. Moreover, natural soils vary in composition, making standardization and quality control difficult. In Mediterranean climates, vapour-open materials can support passive moisture regulation. However, seasonal changes in solar exposure and rainfall make full-scale assessment under real operating conditions necessary. This study assesses the in situ hygrothermal behaviour of an experimental circular earthen plaster, formulated with marble-processing dust and sisal fibres, against a natural hydraulic lime (NHL) reference. Two near-identical hollow-clay-block masonry test boxes were built near Catania (Southern Italy, Köppen Csa) and monitored under free-running conditions across winter, transition and summer campaigns in 2026, recording surface temperatures, indoor air temperature, relative humidity and CO₂. In winter, the earthen finish reduced the daily internal surface amplitude from 4.9 °C to 4.2 °C consistently on every paired monitoring day. During the transition period, surface differences were negligible, but relative humidity emerged as the discriminating variable, the earthen room remaining higher and more stable. In summer, the hygroscopic buffering became most evident, with the earthen room holding indoor humidity near 72% almost unchanged across a near-five-degree seasonal warming. A difference in solar absorptance between the two external finishes was identified and quantified, reducing the external surface peak of the earthen prototype by about 2 °C at maximum west-wall irradiance. The results support the use of full-scale monitoring for circular earthen plasters, advancing scientific understanding of circular earthen plasters under Mediterranean exposure and providing applied evidence for their performance-oriented use. Full article

In this article, static durability testing is combined with an economic analysis of selected furniture manufactured from solid oak residues. Durability was assessed under the EN 1728 and EN 12520 static-load procedures, and dimensional stability was examined using statistical process-control tools (normality analysis, kurtosis and Shewhart control charts). Chairs intended for children were tested for the body mass of five-, seven- and nine-year-old children, as well as for an adult (seat force F1 = 250–850 N, backrest force F2 = 90–290 N). The tested chairs met the strength and durability requirements of the applied standards, and none overturned or tended to tip. A manufacturing cost and profitability analysis then quantified the cost structure. Material accounted for only 10–31% of manufacturing costs, with labour as the dominant component, reflecting the labour intensity of upcycling irregular residues into individually designed furniture. Manufacturing costs per item ranged from PLN 108 to PLN 251 against trial sale prices of PLN 250 to PLN 1300, yielding net profit margins of 46–81%. The findings indicate that upcycling post-production residues can improve the economic and potential environmental performance of furniture enterprises and support circular-economy objectives by reducing demand for virgin timber. Full article

The global construction industry is increasingly seeking sustainable alternatives to conventional structural materials to reduce environmental impacts and support circular economy goals. This review examines bio-based construction materials from a structural engineering perspective, focusing on the transition from intrinsic material properties to member-level behavior and system-scale applications. A combined bibliometric and “From Material to Member” framework is used to connect microstructural characteristics with structural performance across scales. The review covers microbial self-healing concretes, engineered bamboo, plant-aggregate concretes such as hempcrete and rice-husk composites, lignin-based polymers and resins, and mycelium composites, with emphasis on materials and systems relevant to structural and member-scale applications. Bio-based materials developed primarily for asphalt and pavement applications are outside the scope of this review. Mechanical, thermal, durability, and environmental performance are evaluated alongside emerging multi-scale modeling approaches and hybrid structural systems. The findings show that bio-concretes can provide autonomous crack repair, engineered bamboo offers high strength-to-weight efficiency, and lignin-based polymers enable renewable composite matrices with adaptable properties. However, challenges remain regarding connection design, moisture sensitivity, long-term durability, standardization, and the transfer of laboratory findings to structural-scale reliability. Life-cycle assessment studies indicate substantial embodied carbon reduction potential, although outcomes depend on processing methods, service-life assumptions, and end-of-life scenarios. Overall, performance-based design, durability assessment, standardized testing, and dynamic life-cycle approaches are essential for broader structural implementation. Full article