Recycling

53 pages, 1491 KB

Open AccessArticle

Implementing the LCCE5.0 Framework (Lean Construction, Circular Economy, and Construction 5.0) in the Moroccan Construction Sector

by Abderrazzak El Hafiane, Abdelali En-nadi and Mohamed Ramadany

Recycling 2026, 11(3), 63; https://doi.org/10.3390/recycling11030063 - 19 Mar 2026

Viewed by 537

Abstract

Integrating Lean Construction (LC), the Circular Economy (CE), and Construction 5.0 (C5.0) remains challenging in emerging delivery contexts. This difficulty increases when procurement routines determine which practices become enforceable across tendering, contracting, and site execution. This study prioritized barriers to LCCE5.0 implementation in [...] Read more.

Integrating Lean Construction (LC), the Circular Economy (CE), and Construction 5.0 (C5.0) remains challenging in emerging delivery contexts. This difficulty increases when procurement routines determine which practices become enforceable across tendering, contracting, and site execution. This study prioritized barriers to LCCE5.0 implementation in Morocco and translated expert judgments into actionable recommendations. A structured literature review informed the barrier inventory and conceptual framing. The study proposed a three-layer, life-cycle LCCE5.0 framework that links governance, operational routines, and digital enablers. It operationalized 40 critical barrier factors across six dimensions and five life-cycle macro-phases. A two-round Delphi study was conducted with 22 Moroccan experts using a 7-point Likert scale. Barriers were ranked using Round 2 (T2) medians with ties resolved using the interquartile range. Top-box agreement (ratings of 6–7) and consensus tiers were reported. The ranking showed strong stability across rounds, with 92.5% of barrier factors remaining stable. Kendall’s W at T2 equaled 0.817 (p < 0.001), indicating high panel consensus. Results indicated that constraints clustered in upstream governance. Three procurement-centered regulatory and contractual barriers topped the ranking (Mdn_T2 = 7). These barriers reflected missing CE procurement guidelines, limited weighting of environmental criteria, and the absence of circularity and digital requirements in tenders. Six additional barriers reinforced this procurement bottleneck. They included limited owner commitment, weak enforcement authority, limited top-management commitment, and regulatory instability. They also included low interorganizational trust, limited risk-sharing contracts, and tool-centered deployment of LCCE5.0 practices. These findings support procurement-focused recommendations to institutionalize auditable circular requirements and data-enabled verification in tendering and contracting routines. The proposed LCCE5.0 mechanism and the resulting recommendations require empirical validation beyond this Delphi-based prioritization. Full article

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34 pages, 1940 KB

Open AccessArticle

Mapping Polyester Waste Stream and Recyclability: A Material Flow Analysis of Indonesia’s Textile and Clothing Industry

by Siti Nurkomariyah, Dodik Ridho Nurrochmat, Dikky Indrawan and Harianto

Recycling 2026, 11(3), 62; https://doi.org/10.3390/recycling11030062 - 19 Mar 2026

Viewed by 488

Abstract

Indonesia, as a major global textile exporter, faces substantial sustainability challenges due to its linear production model, which generates massive volumes of post-industrial polyester waste (PIPW). However, reliable data and recycling pathways remain critically lacking. This study quantifies the volume, composition, and textile-to-textile [...] Read more.

Indonesia, as a major global textile exporter, faces substantial sustainability challenges due to its linear production model, which generates massive volumes of post-industrial polyester waste (PIPW). However, reliable data and recycling pathways remain critically lacking. This study quantifies the volume, composition, and textile-to-textile (T2T) recyclability potential of PIPW across Indonesia’s national textile and clothing production chain, employing a mixed-methods approach that integrates material flow analysis (MFA), site visits, and stakeholder interviews. The results indicate that 572 kilotonnes of PIPW were generated in 2023, with garment manufacturing identified as the most waste-intensive. Nineteen waste types were identified; 61% comprise fibre blends, which significantly constrain closed-loop recycling. A novel five-tier waste typology was developed to classify waste streams based on material characteristics, technological availability, and economic feasibility. The circularity map reveals that Indonesia is trapped in pseudo-circularity. Scenario analysis suggests that up to 184 kilotonnes of PIPW could be feasibly redirected towards higher-value chemical recycling. The research recommends mandatory source segregation, fiscal incentives, investment in chemical recycling infrastructure, and the integration of circular design into national standards. The study provides the first national-level MFA of PIPW in Indonesia and establishes an empirical baseline to advance T2T recycling in emerging economies. Full article

(This article belongs to the Special Issue Advancing the Circular Economy: A Life Cycle Perspective on Waste Valorization)

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16 pages, 1442 KB

Open AccessArticle

Aerobic and Energy-Recovery Treatment Processes of Sanitary Waste to Reduce End-of-Life Carbon Emissions

by Gidalti García Cabrera, José Aurelio Sosa Olivier, Guadalupe Hernández Gerónimo, José Ramón Laines Canepa, Alejandro Padilla Rivera, Gabriel Núñez-Nogueira and María del Carmen Cuevas Díaz

Recycling 2026, 11(3), 61; https://doi.org/10.3390/recycling11030061 - 19 Mar 2026

Viewed by 238

Abstract

Greenhouse gas (GHG) emissions from sanitary waste (SW) are not usually quantified in institutional inventories, which limits the ability to assess its management and associated carbon footprint. This study establishes emission factors (EF) for SW generated in a higher education institution (HEI), focusing [...] Read more.

Greenhouse gas (GHG) emissions from sanitary waste (SW) are not usually quantified in institutional inventories, which limits the ability to assess its management and associated carbon footprint. This study establishes emission factors (EF) for SW generated in a higher education institution (HEI), focusing on toilet paper. In 2022, 19 sanitary waste sources were monitored, obtaining a per capita generation of 3.02 g person⁻¹ day⁻¹ and an annual total of 356.87 kg of SW. Samples were characterized through proximate and elemental analyses, applying stoichiometric calculations for two disposal-site degradation pathways: Aerobic: 841.95 kg (total climate indicator) t⁻¹ SW, and Anaerobic: 7041.97 kg (total climate indicator) t⁻¹. The arithmetic mean of the aerobic and anaerobic EFs was 3941.96 kg (total climate indicator) t⁻¹ SW. Based on an estimated annual mass of 1.12 t yr⁻¹, emissions ranged from 0.35 to 6.71 t yr⁻¹ (total climate indicator: CO₂ + CH₄-derived CO₂e) depending on the scenario. Emissions could be reduced by over 90% when aerobic degradation or controlled methane capture predominates. The results suggest that separating SW at its point of generation and ensuring that it undergoes aerobic or energy-recovery treatment processes can limit its contribution to institutional GHG inventories. Having material-specific EF enables quantitative comparison among management strategies and guides continuous-improvement decisions. Full article

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21 pages, 4328 KB

Open AccessArticle

Delamination of Aluminium Current Collectors from Spent Lithium-Ion Battery Cathodes Using Room-Temperature Organic Acid-Assisted Ultrasonication

by Tendai Tawonezvi, Anele Sinto, Mihle N. Qhina, Dorcas Zide, Emihle Mlotha and Bernard J. Bladergroen

Recycling 2026, 11(3), 60; https://doi.org/10.3390/recycling11030060 - 16 Mar 2026

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Abstract

The strong adhesion between cathode materials and aluminium (Al) foil substrates presents a significant challenge in the recycling of spent lithium-ion batteries (LiBs). Conventionally, high temperatures and high concentrations of costly organic solvents such as N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAC), dimethylformamide (DMF), and dimethyl [...] Read more.

The strong adhesion between cathode materials and aluminium (Al) foil substrates presents a significant challenge in the recycling of spent lithium-ion batteries (LiBs). Conventionally, high temperatures and high concentrations of costly organic solvents such as N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAC), dimethylformamide (DMF), and dimethyl sulfoxide (DMSO) are used to enhance ultrasonication-based delamination. In this study, a novel, eco-efficient approach was demonstrated for delaminating cathode materials from Al foil using a low-concentration organic citric-acid-assisted low-power ultrasonic treatment coupled with a gentle, low-power-per-volume mechanical mixing system at room temperature. The separation mechanism was attributed to the structure disruption, possibly swelling, of the polyvinylidene fluoride (PVDF) binder using low-concentration citric acid and the cavitation effects induced by ultrasound. Key parameters influencing the delamination efficiency included the solvent type, temperature, ultrasonic power, and treatment duration. Under optimised conditions, citric acid was used as the sonication reagent, with a process temperature of 20 °C, 60 W ultrasonic power, and 80 min of ultrasonication; a delamination efficiency of approximately 92% was achieved. The recovered cathode materials exhibited low agglomeration, favouring subsequent leaching processes. This work proposes an environmentally friendly and effective method for cathode and Al foil recovery from spent LiBs, integrating manual dismantling, ultrasonic treatment, and material separation. Full article

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20 pages, 36258 KB

Open AccessArticle

Recovery of Valuable Metals from Spent Lithium-Ion Batteries by Combining Reduction Roasting and Selective Leaching

by Ruijiao Zhai, Kui Huang, Shanjin Mao, Rugui Li, Haili Dong and Xi Zhai

Recycling 2026, 11(3), 59; https://doi.org/10.3390/recycling11030059 - 10 Mar 2026

Viewed by 446

Abstract

Amid growing environmental pressure and increasing demand for resource sustainability, the efficient recovery of valuable metals from spent lithium-ion batteries (LIBs) has become a critical challenge in the field of resource recycling. Therefore, a novel approach is presented for selective lithium (Li) and [...] Read more.

Amid growing environmental pressure and increasing demand for resource sustainability, the efficient recovery of valuable metals from spent lithium-ion batteries (LIBs) has become a critical challenge in the field of resource recycling. Therefore, a novel approach is presented for selective lithium (Li) and manganese (Mn) separation from LiNi_xCo_yMn_1−x−yO₂ by combining carbothermic reduction roasting and selective leaching. Low-cost glucose (C₆H₁₂O₆) was selected as the reduction roasting reductant, which converts the cathode materials into water-soluble lithium carbonate (Li₂CO₃), water-insoluble cobalt (Co), nickel (Ni), and manganese oxide (MnO). Wet magnetic separation was employed to preferentially extract Li while simultaneously removing excess carbon from Ni, Co, and MnO. Under optimal roasting conditions at 600 °C for 90 min followed by wet magnetic separation with a liquid–solid ratio of 30 mL/g for 30 min, 95.42% of Li was preferentially extracted. Subsequently, at a formic acid (HCOOH) concentration of 1.6 mol/L, liquid–solid ratio of 6 mL/g, and leaching time of 30 min, 94.29% of Mn was selectively extracted from the wet magnetic separation products, whereas Ni and Co were leached at 6.13% and 7.22%, respectively. The acid-leaching residue can be recycled as a Ni-Co alloy. Full article

(This article belongs to the Topic Waste Management for Recycling and Environmental Protection)

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16 pages, 2220 KB

Open AccessArticle

Investigations on the Effects of Granite Sawdust on the Pore Structure of Dry-Mixed Mortar and Its Mechanical Properties

by Zhiji Gao, Jin’an Xu, Hanjie Qiu, Maoxin Shi, Siyao Li, Rusheng Qian, Jingchen Luo, Fanli Wu, Haibo Nie and Tengfei Ma

Recycling 2026, 11(3), 58; https://doi.org/10.3390/recycling11030058 - 6 Mar 2026

Viewed by 331

Abstract

Granite sawdust is a by-product in the process of stone processing, which is usually piled up, thus easily causing environmental pollution. To achieve resource utilization, granite sawdust was used as a partial substitution of cement in this work. The effects of different sawdust [...] Read more.

Granite sawdust is a by-product in the process of stone processing, which is usually piled up, thus easily causing environmental pollution. To achieve resource utilization, granite sawdust was used as a partial substitution of cement in this work. The effects of different sawdust contents (10–50%) were systematically studied on the pore structure and the mechanical properties of its dry powder mortar. Combined with the grey correlation theory, the correlation between pore size distribution and compressive strength was analyzed. The results showed that the consistency and mechanical properties of the mortar gradually decreased along with the increasing sawdust content, while its critical pore-diameter decreased. The mortar performance was the best when its sawdust content is 10%, which meets the M25 technical requirements. When content reaches up to 30%, the mortar still met the strength standard of M20. Compared to fly ash, the mortar with 30% sawdust as the substitution has a higher water retention rate but lower mechanical strength. The grey correlation analysis indicated that the pores with diameters less than 10 nm and greater than 1000 nm had the most significant impact on the compressive strength. Full article

(This article belongs to the Topic Converting and Recycling of Waste Materials)

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18 pages, 1282 KB

Open AccessArticle

The Use of Fresnel Lens Softening Stations to Improve Recycling Feasibility of Injection-Molding Purges

by Ma. Guadalupe Plaza, Maria Luisa Mendoza López, José de Jesús Pérez Bueno, Edain Belén Pérez Mendoza and Martha Elva Pérez Ramos

Recycling 2026, 11(3), 57; https://doi.org/10.3390/recycling11030057 - 5 Mar 2026

Viewed by 388

Abstract

Injection-molding purges are heterogeneous, bulky residues whose uncertain composition and irregular geometry hinder direct reinsertion, making cold shredding costly and maintenance-intensive. This work develops a low-infrastructure solar-assisted pre-processing route using a PMMA Fresnel lens to induce controlled sub-onset softening and enable clean shear [...] Read more.

Injection-molding purges are heterogeneous, bulky residues whose uncertain composition and irregular geometry hinder direct reinsertion, making cold shredding costly and maintenance-intensive. This work develops a low-infrastructure solar-assisted pre-processing route using a PMMA Fresnel lens to induce controlled sub-onset softening and enable clean shear cutting without destructive thermal histories. The sub-onset softening is here defined into a viscoelastically active range (at or above T_g for the amorphous phase) while remaining below the melting onset (T_m, onset) and below the onset of thermal degradation (T_d, onset). The station was engineered via QFD and risk-oriented design tools, while a weighted Pugh matrix selected shear cutting over saw-based alternatives. A screening factorial DOE showed that lens height, angle, and their interaction significantly govern focal-spot diameter and receiver temperature, yielding linear relations for conservative set-point selection. Receiver benchmarking further indicated that copper reaches substantially higher temperatures than graphite under identical exposure conditions, supporting copper as the simplest, rapid-heating receiver. Under DOE-calibrated operation, tear-free shear cutting was achieved across representative purge families (PP–ABS, PC–ABS–PP, PA66, PA66-filler, and POM) without forced convection. From a recycling and waste-management perspective, the approach converts bulky purge scrap into mill-compatible feedstock with reduced mechanical resistance, lowering tool wear and fines generation, accelerating downsizing, and limiting stockpiling that elevates combustible-inventory fire risk. Overall, the proposed DOE-calibrated, operator-friendly framework improves recycling feasibility by enabling safer handling, more stable preprocessing throughput, and reduced reliance on disposal or long-term storage for heterogeneous industrial purges. Full article

(This article belongs to the Special Issue Celebrating 10 Years of Recycling: Shaping the Future of Waste Management)

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29 pages, 1355 KB

Open AccessReview

Waste-to-Energy Technologies and Their Role in Municipal Solid Waste Management

by Harrison Appiah, Paul Asamoah and Armando Gabriel McDonald

Recycling 2026, 11(3), 56; https://doi.org/10.3390/recycling11030056 - 5 Mar 2026

Cited by 2 | Viewed by 1363

Abstract

Rising global municipal solid waste (MSW) generation poses severe environmental and resource challenges, necessitating sustainable management strategies beyond landfilling. This review critically synthesizes thermochemical waste-to-energy (WtE) technologies, including incineration, pyrolysis, gasification, and hydrothermal carbonization, as viable pathways for converting heterogeneous MSW into energy [...] Read more.

Rising global municipal solid waste (MSW) generation poses severe environmental and resource challenges, necessitating sustainable management strategies beyond landfilling. This review critically synthesizes thermochemical waste-to-energy (WtE) technologies, including incineration, pyrolysis, gasification, and hydrothermal carbonization, as viable pathways for converting heterogeneous MSW into energy (electricity, heat, syngas, bio-oil) and valuable materials (biochar, ash for construction). Drawing on recent literature, it highlights their superior greenhouse gas reductions, energy recovery efficiencies, and residue valorization potential compared to traditional disposal, while addressing persistent limitations such as feedstock variability, tar formation, high capital costs, and stringent emission controls. Advanced variants and integration with circular economy principles enhance feasibility, particularly in diverse regional contexts. Despite technical and economic barriers, thermochemical WtE offers a transformative approach to resource-efficient waste management, supporting zero-waste goals and renewable energy transitions when combined with optimized pre-treatment, policy incentives, and ongoing innovation in process efficiency and pollutant mitigation. Full article

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13 pages, 3145 KB

Open AccessArticle

Utilizing Industrial Waste to Enhance Mechanical Strength and Cost-Effectiveness of Dredged Soil

by Jinzhao Li, Xin Zuo and Changchun Xin

Recycling 2026, 11(3), 55; https://doi.org/10.3390/recycling11030055 - 5 Mar 2026

Viewed by 428

Abstract

The large-scale dredging activities in port areas generate substantial quantities of dredged soil, leading to land occupation and disposal challenges, while industrial wastes such as fly ash and desulfurization gypsum remain underutilized. In this study, industrial wastes were employed as a curing agent [...] Read more.

The large-scale dredging activities in port areas generate substantial quantities of dredged soil, leading to land occupation and disposal challenges, while industrial wastes such as fly ash and desulfurization gypsum remain underutilized. In this study, industrial wastes were employed as a curing agent to stabilize dredged soil, aiming to achieve both mechanical performance improvement and cost-effective recycling. In total, 100 g of curing agent was added to 1 kg of sludge. The optimal strength-maximizing formulation comprised 4.5% activator 1 #, 4.5% fly ash, 4.5% mineral powder, and 0.5% desulfurization gypsum. It achieved an unconfined compressive strength of 0.794 MPa. For enhanced cost-effectiveness, a modified binder blend (1.88% activator 1 #, 4.5% fly ash, 4.5% mineral powder, and 0.5% desulfurization gypsum) delivered 0.63 MPa at 28 days, satisfying mechanical construction specifications. Results demonstrate that unconfined compressive strength increases with solid wastes; however, with the extension of solidification time, the unconfined compressive strength of dredged soil gradually slows down. Full article

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18 pages, 4846 KB

Open AccessArticle

Valorization of Sugarcane Bagasse Ash (SCBA) in Cementitious Composites: Hydration Behavior, Nanomodification and Sustainability Performance

by Javier Rodrigo Nahuat-Sansores, Karla del Carmen García-Uitz, Julio César Cruz-Argüello, Carlos Andrés Ramírez-Pinto, Ricardo Enrique Vega-Azamar, Danna Lizeth Trejo-Arroyo and Yazmin Vidal Valdez

Recycling 2026, 11(3), 54; https://doi.org/10.3390/recycling11030054 - 5 Mar 2026

Viewed by 447

Abstract

Sugarcane bagasse ash (SCBA) has been widely studied as a partial supplementary cementitious material; nonetheless, its hydration behavior and performance when combined with nanoscale modifiers remain insufficiently understood. The aim of this study is to assess the pozzolanic potential of SCBA, the hydration [...] Read more.

Sugarcane bagasse ash (SCBA) has been widely studied as a partial supplementary cementitious material; nonetheless, its hydration behavior and performance when combined with nanoscale modifiers remain insufficiently understood. The aim of this study is to assess the pozzolanic potential of SCBA, the hydration behavior of binary SCBA–cement composites and the mechanical performance of ternary mortars with silica nanoparticles (Si-NPs). SCBA reactivity was confirmed by a Chapelle index of ~300 mg Ca(OH)₂/g, while hydration development in binary pastes (5–20 wt% SCBA) was quantified using TG/dTG and semi-quantitative XRD. Low SCBA replacement levels (5–10 wt%) enhanced the hydration degree by up to ~12% at 28 days compared with the reference paste. Ternary mortars incorporating 5 wt% SCBA and Si-NPs exhibited significant strength gains, with the optimal blend (2.5 wt% Si-NPs) achieving a 42% increase in 28-day compressive strength relative to the reference mortar. A sustainability assessment showed concurrent reductions in clinker intensity and CO₂ intensity of approximately 33% and 32%, respectively. These findings support the sustainable and technical viability of combining agro-industrial waste and nanotechnology as complementary strategies for reducing clinker content while enhancing eco-efficiency in alternative cementitious composites. Full article

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21 pages, 4913 KB

Open AccessArticle

Comprehensive Assessment and Long-Term Monitoring of High-Red-Brick-Content Recycled Aggregates from Rural Construction and Demolition Waste: A Study on Inorganic Composite Material Performance

by Pengfei Li, Jie Ji, Daiyue Wang, Chuan Qiu, Ran Zhang and Yanling Li

Recycling 2026, 11(3), 53; https://doi.org/10.3390/recycling11030053 - 5 Mar 2026

Viewed by 400

Abstract

The durability characteristics of inorganic mixtures incorporating recycled aggregates from rural residential construction and demolition waste with high red brick content remain inadequately elucidated. To illuminate their long-term serviceability, two types of recycled aggregate inorganic mixtures (RAIMs) were formulated and implemented in a [...] Read more.

The durability characteristics of inorganic mixtures incorporating recycled aggregates from rural residential construction and demolition waste with high red brick content remain inadequately elucidated. To illuminate their long-term serviceability, two types of recycled aggregate inorganic mixtures (RAIMs) were formulated and implemented in a test road section, with their mechanical properties and fatigue resistance systematically monitored and assessed. Comparative analysis indicated that RAIMs exhibit comparable resistance to permanent deformation and analogous fracture failure mechanisms to natural aggregate inorganic mixtures (NAIMs), yet their elastic deformation recovery capability is compromised. Specifically, RAIMs attained parity with NAIMs in terms of unconfined compressive strength, indirect tensile strength, flexural tensile strength, and static compressive resilient modulus. However, their dynamic compressive resilient modulus, indirect tensile resilient modulus, and flexural tensile resilient modulus were lower than those of NAIMs by over 30%. Furthermore, probabilistic fatigue prediction models for RAIMs were established, facilitating reliable estimation of the service life of RAIMs under various stress intensity levels. This study holds considerable significance for dispelling the inherent perception of RAIMs’ inferior service performance and augmenting the theoretical foundation for their resourceful utilization in road engineering. Full article

(This article belongs to the Special Issue Recycled Materials in Sustainable Pavement Innovation)

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21 pages, 11318 KB

Open AccessArticle

Multistage Recycling of Aluminum Casting Slags: Metal Extraction and Salt Flux Regeneration

by Boris Kulikov, Nikolay Dombrovskiy, Aleksandr Kosovich, Evgeniy Partyko, Yulbarskhon Mansurov, Pavel Yuryev, Nikita Stepanenko, Yuriy Baykovskiy, Alexander Durnopyanov, Ruslan Balanev and Maxim Baranov

Recycling 2026, 11(3), 52; https://doi.org/10.3390/recycling11030052 - 4 Mar 2026

Viewed by 415

Abstract

The depletion of natural resources remains an acute global problem, highlighting the importance of developing sustainable technologies that enable the simultaneous extraction of metals and recycling of waste. This paper describes a study of a technology for recycling aluminum slag from foundries to [...] Read more.

The depletion of natural resources remains an acute global problem, highlighting the importance of developing sustainable technologies that enable the simultaneous extraction of metals and recycling of waste. This paper describes a study of a technology for recycling aluminum slag from foundries to produce secondary aluminum alloy and regenerated flux. Research and processing methods include X-ray phase and spectral analysis of slag composition, multi-stage grinding in a jaw crusher and planetary mill, screening for fraction separation, and selective dissolution of the oxide–salt phase in water or hydrochloric acid followed by filtration and evaporation; obtaining regenerated flux based on phase diagrams of chloride systems; and briquetting and remelting of the extracted aluminum. The technology ensures the extraction of up to 85% of the metallic aluminum from slag and the production of regenerated flux based on the NaCl–KCl–MgCl₂ system with a low melting point. Full article

(This article belongs to the Topic Converting and Recycling of Waste Materials)

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22 pages, 744 KB

Open AccessArticle

Packaging Waste Recycling Rates in Central and Eastern Europe: Trend Analysis of the EU-27 Reference Path

by Ramona Giurea, Ionela Gavrila-Paven and Elena Cristina Rada

Recycling 2026, 11(3), 51; https://doi.org/10.3390/recycling11030051 - 4 Mar 2026

Viewed by 491

Abstract

This paper analyzes the evolution of packaging waste recycling rates in four Central and Eastern European EU Member States—Bulgaria, Hungary, Poland, and Romania—in comparison with the EU-27 average over the period 2014–2023. The analysis is based on Eurostat data on total packaging waste [...] Read more.

This paper analyzes the evolution of packaging waste recycling rates in four Central and Eastern European EU Member States—Bulgaria, Hungary, Poland, and Romania—in comparison with the EU-27 average over the period 2014–2023. The analysis is based on Eurostat data on total packaging waste recycling rates (percentage of generated waste recycled) and employs a linear trend model estimated for the EU-27, which is used as a reference trajectory. This reference trend does not aim to predict future recycling rates or to validate absolute national performance levels; rather, it serves as an analytical benchmark for assessing the relative convergence or divergence of national trajectories over time. Descriptive statistics and linear regression techniques are applied to characterize long-term tendencies and year-to-year dynamics, including potential disruptions during the 2020–2021 period. The results indicate that the EU-27 recycling rate remains high and relatively stable (average 78.7%), albeit with a slight downward trend (−0.44%) across the analyzed interval. Poland and Bulgaria record overall improvements relative to their initial levels, while Hungary—and particularly Romania—exhibit declining trends and persistent negative gaps compared to the EU-27 benchmark. Poland stands out by surpassing the EU-27 average after 2019, reporting exceptionally high recycling rates in several years, whereas Romania consistently records the largest deviation, with an average gap exceeding 20% in the later period. These findings reveal substantial heterogeneity in the implementation of EU packaging waste policies and highlight the need for targeted, country-specific interventions in Member States facing structural constraints in recycling capacity and collection systems. Full article

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29 pages, 10936 KB

Open AccessArticle

Apple Pruning-Derived Activated Biochar and Hydrochar for Efficient Dye Adsorption: Response Surface Methodology-Guided Optimization, Kinetic Analysis, and Mechanistic Modelling

by Ameni Ben Salah, M. Mirari Antxustegi, Eriz Corro and María González Alriols

Recycling 2026, 11(3), 50; https://doi.org/10.3390/recycling11030050 - 4 Mar 2026

Viewed by 481

Abstract

This study explores the valorisation of apple pruning (AP) residues into sustainable carbonaceous adsorbents for dye-contaminated wastewater. Activated biochars (ABCs) were produced via single-step (ABC-1S) and two-step (ABC-2S) KOH activation, while activated hydrochar (AHTC) was obtained through hydrothermal carbonization followed by H₃ [...] Read more.

This study explores the valorisation of apple pruning (AP) residues into sustainable carbonaceous adsorbents for dye-contaminated wastewater. Activated biochars (ABCs) were produced via single-step (ABC-1S) and two-step (ABC-2S) KOH activation, while activated hydrochar (AHTC) was obtained through hydrothermal carbonization followed by H₃PO₄ activation. The materials were comprehensively characterized using proximate analysis, FTIR spectroscopy, SEM imaging, and N₂ adsorption–desorption to evaluate surface chemistry, morphology, and textural properties. Batch adsorption experiments using MB (5–100 mg/L) demonstrated the superior performance of ABCs compared to AHTC. At low dye concentrations, adsorption on ABCs was partially influenced by external mass transfer, while kinetic data were best described by the Avrami model, indicating complex adsorption mechanisms. Isotherm analysis showed that ABC-2S exhibited heterogeneous adsorption behaviour, whereas AHTC poorly conformed to conventional isotherm models. The Langmuir model indicated higher monolayer capacities for ABCs (up to 22.9 mg/g) relative to AHTC (9.7 mg/g), reflecting a greater density of accessible adsorption sites induced by alkaline activation. Notably, nearly complete methylene blue (MB) removal was maintained over three regeneration cycles, confirming the stability, reusability, and practical potential of AP-derived ABCs and AHTC for sustainable wastewater treatment. Full article

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45 pages, 5824 KB

Open AccessReview

Role of Mineral Processing in Enhancing Recycled Concrete Aggregate Quality—A Critical Review

by Priscila Thalita Barros de Lima, Rafael dos Santos Macedo, Maurício Guimarães Bergerman, Anette Müller and Carina Ulsen

Recycling 2026, 11(3), 49; https://doi.org/10.3390/recycling11030049 - 3 Mar 2026

Viewed by 1079

Abstract

Mineral processing may decisively influence recycled aggregate (RA) production, yet it is systematically underreported. This critical review screened 338 Scopus-indexed publications (2004–2024) and retained 204 studies after eligibility assessment. Reporting on comminution was limited: ~52% (105 studies) of studies did not explicitly mention [...] Read more.

Mineral processing may decisively influence recycled aggregate (RA) production, yet it is systematically underreported. This critical review screened 338 Scopus-indexed publications (2004–2024) and retained 204 studies after eligibility assessment. Reporting on comminution was limited: ~52% (105 studies) of studies did not explicitly mention crushing, while ~26% (53 studies) identified the crusher type, and only about 1% (two articles) reported operating conditions, which undermines reproducibility and cross-study comparability. RA quality is application-/market-dependent. The literature was classified into cement-based materials (46.1%), pavement applications (44.6%), and fundamental studies without application (9.3%). For cement-based materials, water absorption and compressive strength were the most frequently reported primary and secondary properties, respectively. For pavement applications, particle-size distribution and optimum moisture content predominated. Overall, mineral processing directly governs the primary attributes of recycled aggregates (RAs) and indirectly influences their secondary performance outcomes. The main gap identified in the literature is the lack of clear recommendations for processing procedures, which limits the reproducibility and comparability of reported results. To address this limitation, this article proposes a mineral-processing framework intended to standardize both RA processing and reporting practices, thereby improving crosslink study comparability, experimental reproducibility, and evidence-based specification according to end-use requirements. Full article

(This article belongs to the Special Issue Recycled Materials in Sustainable Pavement Innovation)

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18 pages, 3937 KB

Open AccessArticle

Chemical Conversion of Waste Tire Ash into Layered Double Hydroxide via Acid Leaching for Phosphorus Removal

by Takaaki Wajima

Recycling 2026, 11(3), 48; https://doi.org/10.3390/recycling11030048 - 3 Mar 2026

Viewed by 279

Abstract

This study investigated a feasible recycling and detoxification process for waste tire ash containing hazardous Zn and Al using acid leaching, followed by layered double hydroxide (LDH) synthesis. The novelty of this work is the direct conversion of a Zn/Al/Fe/Ca-rich real waste system [...] Read more.

This study investigated a feasible recycling and detoxification process for waste tire ash containing hazardous Zn and Al using acid leaching, followed by layered double hydroxide (LDH) synthesis. The novelty of this work is the direct conversion of a Zn/Al/Fe/Ca-rich real waste system into a phosphorus removal material, in which LDH-related uptake and secondary hydroxyapatite formation cooperatively immobilize phosphorus. Waste tire ash mainly consists of Zn, Al, Fe, Ca, and Si, most of which can be effectively leached with hydrochloric acid (HCl). The optimum leaching conditions for high extraction efficiency involved treatment with 10 M HCl for 10 min at 20 °C (solid–liquid ratio: 50 g/L). Under these conditions, the elution concentrations of Zn and Al from the residue decreased to 0.3 and 0.17 mg/L, respectively, meeting the Japanese leaching standards, whereas the raw ash showed significantly higher values. From the leached solution, LDH-containing products with high phosphorus removal capacity were synthesized at 40 °C for 2 h by adjusting the pH to 11.5. A phosphorus removal performance of 2.0 mmol/g was obtained owing to the formation of hydroxyapatite. The combined process of HCl leaching and LDH synthesis enables the detoxification of waste tire ash and the production of an environmental purification material. Full article

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19 pages, 1024 KB

Open AccessReview

Environmental Risks and Sustainable Management Pathways for Used Lubricating Oils: A Structured Review with Conceptual Spill Risk Analysis

by Catherine Cabrera-Escobar, Juan Moreno-Gutiérrez, Rubén Rodríguez-Moreno, Emilio Pájaro-Velázquez, Fátima Calderay-Cayetano and Vanesa Durán-Grados

Recycling 2026, 11(3), 47; https://doi.org/10.3390/recycling11030047 - 2 Mar 2026

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Abstract

Used lubricating oils (ULOs) represent one of the largest hazardous liquid waste streams globally and pose significant environmental risks if improperly managed. This study presents a structured review of ULO management pathways, including regeneration, reprocessing, and energy recovery technologies, within a sustainability and [...] Read more.

Used lubricating oils (ULOs) represent one of the largest hazardous liquid waste streams globally and pose significant environmental risks if improperly managed. This study presents a structured review of ULO management pathways, including regeneration, reprocessing, and energy recovery technologies, within a sustainability and circular economy framework. The review systematically categorizes treatment options based on recovery efficiency, waste generation, environmental performance, and technical feasibility. To contextualize environmental risk, a conceptual numerical spill dispersion analysis using the SIMOIL model is included as an illustrative case study under simplified marine conditions. The simulation highlights the rapid dispersion potential of ULOs in coastal environments, reinforcing the need for preventive management strategies. The analysis indicates that refining technologies generally offer higher material circularity potential, while thermochemical processes provide viable alternatives for heavily contaminated oils. The study identifies critical gaps in technoeconomic comparability, regulatory harmonization, and source segregation practices. Strengthening integrated management systems is essential to minimize environmental impact and enhance resource recovery. Full article

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23 pages, 12039 KB

Open AccessArticle

Synthesis of Phosphoanhydrite Binders Based on Phosphogypsum from Various Industrial Sources

by Nataliya Alfimova, Kseniya Levickaya, Ivan Nikulin, Mikhail Lebedev and Natalia Kozhukhova

Recycling 2026, 11(3), 46; https://doi.org/10.3390/recycling11030046 - 2 Mar 2026

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Abstract

Phosphogypsum is one of the most widely produced gypsum-containing wastes. Therefore, researchers worldwide are exploring ways to recycle them. It is most often considered as an alternative to natural gypsum in the production of calcium sulfate hemihydrate. There are also isolated studies aimed [...] Read more.

Phosphogypsum is one of the most widely produced gypsum-containing wastes. Therefore, researchers worldwide are exploring ways to recycle them. It is most often considered as an alternative to natural gypsum in the production of calcium sulfate hemihydrate. There are also isolated studies aimed at producing insoluble anhydrite (CaSO₄ II) from phosphogypsum. Compared to hemihydrate, anhydrite is characterized by greater strength and water resistance, and compared to Portland cement, it demonstrates lower energy consumption and CO₂ emissions during production. This study examined the possibility of phosphoanhydrite binder (CaSO₄ II) synthesis by calcination at 600, 800, and 1000 °C of phosphogypsum from four different industrial plants. Phosphoanhydrite binders capable of self-hardening, without the use of special additives, were synthesized. Their maximum strength at 28 days reached 57 MPa, and 69 MPa at 90 days. New data have been obtained regarding the influence of initial phosphogypsum characteristics and calcination temperature on the properties of CaSO₄ II and the hardened phosphoanhydrite paste. Full article

(This article belongs to the Topic Circular Materials Engineering: Waste Valorization and Sustainable Applications)

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21 pages, 5543 KB

Open AccessArticle

Evaluation of Mechanical Properties and Interface Interactions in Thermoplastic Composites Including Discarded Musical Instrument Reeds

by Tetsuo Takayama and Syunsuke Oneda

Recycling 2026, 11(3), 45; https://doi.org/10.3390/recycling11030045 - 2 Mar 2026

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Abstract

This study investigates the material recycling potential of discarded wind instrument reeds (Arundo donax), which are conventionally incinerated, by compounding them with thermoplastics (thermoplastic polyolefin, TPO; polybutylene succinate, PBS). After recovered reeds were pulverized and injection-molded at 10 and 30 wt% [...] Read more.

This study investigates the material recycling potential of discarded wind instrument reeds (Arundo donax), which are conventionally incinerated, by compounding them with thermoplastics (thermoplastic polyolefin, TPO; polybutylene succinate, PBS). After recovered reeds were pulverized and injection-molded at 10 and 30 wt% concentrations, their mechanical and interfacial properties were evaluated. Experimentally obtained results indicate that waste reeds function as effective reinforcing agents, particularly when combined with biodegradable PBS. Incorporating 30 wt% reed flour into PBS enhanced flexural strength by approximately 1.7 times and flexural modulus by 2.8 times compared to the neat resin. This superior performance relative to TPO composites is attributed to robust interfacial hydrogen bonding among PBS carbonyl groups and the hydroxyl groups on the reed surface. Additionally, thermal and spectroscopic analyses revealed that these strong interactions elevate the crystallization temperature and generate a “Rigid Amorphous Phase” (RAF) that facilitates efficient stress transfer. These research findings demonstrate the feasibility of creating high-quality, bio-based composites, offering a sustainable method to reduce petroleum reliance and carbon dioxide emissions by upcycling musical waste. Full article

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16 pages, 1714 KB

Open AccessArticle

Pyrolysis of Recycled LLDPE/LDPE Polymer Blend: Optimization of Process Parameters for High Yield of Wax

by Oluwatobi Elijah Akindele, Jinfeng Zhang, Yuxin Liu and Uttandaraman Sundararaj

Recycling 2026, 11(3), 44; https://doi.org/10.3390/recycling11030044 - 1 Mar 2026

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Abstract

This study evaluates the pyrolysis of recycled linear low-density and low-density polyethylene (rLLDPE/rLDPE) blends for producing wax suitable as a precursor for corrosion-resistant coatings. Experiments were performed in a horizontal quartz tubular reactor under argon, and we investigated different pyrolysis temperature (400, 450, [...] Read more.

This study evaluates the pyrolysis of recycled linear low-density and low-density polyethylene (rLLDPE/rLDPE) blends for producing wax suitable as a precursor for corrosion-resistant coatings. Experiments were performed in a horizontal quartz tubular reactor under argon, and we investigated different pyrolysis temperature (400, 450, 500 °C), residence time (45, 60, 75 min), and heating rate (3, 5, 10 °C min⁻¹). Factorial design and response surface methodology (RSM) were applied to quantify factors and optimize wax yield. Analysis of Variance (ANOVA) indicated statistically significant models (p < 0.05), with heating rate having the highest standardized effect. The highest measured yield was 82% at 400 °C, 75 min, and 3 °C min⁻¹; the DOE optimizer predicted an 84% yield at 400 °C, 45 min, and 3 °C min⁻¹. Product quality was assessed by GC-MS analysis, which showed that the waxes were predominantly composed of 1-alkenes and n-alkanes (C9–C32), consistent with the literature and closely matching compositions of commercial waxes. Overall, slow heating at low temperature with short residence time maximized wax yield without compromising quality, confirming that pyrolysis of recycled PE is a viable route to produce high-yield, specification-consistent waxes suitable for protective coating applications. Full article

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15 pages, 3651 KB

Open AccessArticle

Hyperspectral Imaging Coupled with Machine Learning for Accurate Color Classification of Glass Fragments in Recycling Processes

by Giuseppe Bonifazi, Giuseppe Capobianco, Roberta Palmieri and Silvia Serranti

Recycling 2026, 11(3), 43; https://doi.org/10.3390/recycling11030043 - 1 Mar 2026

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Abstract

Glass is a highly recyclable material that provides substantial environmental benefits, including savings in raw materials and energy as well as a reduction in CO₂ emissions. To ensure the production of high-quality secondary raw materials, container glass from municipal waste separate collection [...] Read more.

Glass is a highly recyclable material that provides substantial environmental benefits, including savings in raw materials and energy as well as a reduction in CO₂ emissions. To ensure the production of high-quality secondary raw materials, container glass from municipal waste separate collection must be accurately separated by color in recycling plants, where only minimal color mixing is tolerated. Color sorting is therefore a key step in glass recycling, as it directly affects both the quality and the market value of recycled cullet. Given the increasingly stringent color quality requirements for recycled glass and the high fraction of cullet used in container glass, advanced technological solutions are needed to improve sorting accuracy. In this study, a visible–near-infrared (VIS-NIR: 400–1000 nm) hyperspectral imaging (HSI) approach integrated with machine learning (ML) is proposed for the automated classification of post-consumer glass fragments from bottles and jars into five color categories: brown, dark green, light green, half-white and white. A hierarchical Partial Least Squares-Discriminant Analysis (PLS-DA) model combined with an object-based analysis strategy was developed to optimize color recognition. The proposed system achieved sensitivity and specificity values between 0.910 and 1.000, demonstrating excellent robustness and predictive capability. Validation on independent datasets confirmed the model’s reliability, with all color glass fragments correctly classified at the object level. The results highlight the potential of HSI-ML systems to enhance color sorting accuracy and process efficiency in recycling plants, contributing to improved material recovery and the advancement of sustainable, circular glass production. Full article

(This article belongs to the Topic Waste Management for Recycling and Environmental Protection)

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Recycling, Volume 11, Issue 3 (March 2026) – 21 articles

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