Recycling

27 pages, 2232 KiB

Open AccessReview

An Analytical Review of Construction and Demolition Waste Management and Quantification Methods Using a Science Mapping Approach

by Weihan Sun, Quddus Tushar, Guomin Zhang, Andy Song, Lei Hou, Jingxuan Zhang and Shuxi Wang

Recycling 2025, 10(3), 115; https://doi.org/10.3390/recycling10030115 - 9 Jun 2025

Abstract

Construction and demolition waste (CDW) management remains a pressing challenge in the construction industry, contributing significantly to environmental degradation and resource depletion. Accurate waste measurement is essential for improving resource recovery and circular economy adoption. However, existing research lacks standardised estimation methods, the [...] Read more.

Construction and demolition waste (CDW) management remains a pressing challenge in the construction industry, contributing significantly to environmental degradation and resource depletion. Accurate waste measurement is essential for improving resource recovery and circular economy adoption. However, existing research lacks standardised estimation methods, the integration of digital technologies, and comprehensive lifecycle analysis approaches, limiting the effectiveness of waste prediction and management strategies. This study addresses the gap by conducting a scientometric analysis using CiteSpace and SciMAT, examining research trends, thematic clusters, and knowledge evolution in CDW quantification and management from 2014 to 2024. It establishes a conceptual framework for integrating digital systems and sustainable practices in CDW, focusing on waste generation rate, carbon emission, and phase-based waste management analysis. Network cluster analysis reveals the integral role of estimation tools and modelling techniques in refining waste generation quantification for building constructions. It also examines the interplay of digital tools, their influence on environmental cost reduction, and factors affecting waste production and environmental protection across project phases. This conjugate approach highlights the importance of the successful implementation of waste quantification and the imperative of machine learning for further investigation. This review offers an evidence-based framework to identify key stakeholders, guide future research, and implement sustainable waste management policies. Full article

► Show Figures

Figure 1

15 pages, 4184 KiB

Open AccessArticle

Characterization of Cellulose and Starch Degradation by Extracellular Enzymes in Frankia Strains

by Medhat Rehan and Ahmed Alzoheiry

Recycling 2025, 10(3), 114; https://doi.org/10.3390/recycling10030114 - 7 Jun 2025

Viewed by 151

Abstract

Annually, a considerable amount of agricultural waste is produced leading to serious environmental pollution if not managed effectively. A wide range of bio-decomposers, including fungi, bacteria, and actinomycetes may break down the complex agro-residues in an eco-friendly way through secreting many cellulolytic and [...] Read more.

Annually, a considerable amount of agricultural waste is produced leading to serious environmental pollution if not managed effectively. A wide range of bio-decomposers, including fungi, bacteria, and actinomycetes may break down the complex agro-residues in an eco-friendly way through secreting many cellulolytic and amylolytic enzymes. The present study aimed at exploring the ability of Frankia to degrade cellulose and starch and identifying the cellulase and α-amylase genes in Frankia genomes for potential agricultural waste degradation. Frankia alni ACN14a and Frankia casuarinae CcI₃ produced clear zones around growing hyphae on carboxymethyl cellulose (CMC) and starch substrates. The hydrolytic index (HI) ranged from 1 to 2.14 reflecting variation in their degradation efficacy. Quantification of CMCase (carboxymethyl cellulase) production in strain ACN14a presented the maximum activity (0.504 U/mL) under 1% CMC after 16 days whereas strain CcI₃ produced a weak activity after 6 days from incubation. Besides, amylase activity in strain ACN14a reached the highest value (3.215 U/mL) after 4 days of growing with 1% starch, while strain CcI₃ had the superior production (3.04 U/mL) after 12 days from 1% starch condition. Data mining and genome blasting led to the identification of multiple genes related to cellulose and starch degradation. Two endoglucanases (celA1, FRAAL4955 and celA2, FRAAL4956), two glycosyl hydrolase family 16 (FRAAL6120 and FRAAL2663), and one glycosyl hydrolase family 16 (Francci3_3843) were predicted in the two genomes. Likewise, the α-amylase genes (FRAAL5900) from Frankia alni ACN14a and (Francci3_3679) from strain CcI₃ were identified. The gene expression of endo-1, 4-beta-glucanase (celA2, FRAAL4956) revealed the maximum increment in its mRNA abundance under 0.25% CMC exposure and showed a 3.3-fold increase. Frankia capability to degrade cellulose and starch represents a critical process in nutrient cycling and environment protection. Full article

(This article belongs to the Special Issue Biomass Revival: Rethinking Waste Recycling for a Greener Future)

► Show Figures

Figure 1

27 pages, 2759 KiB

Open AccessReview

A Review of Global Municipal Solid Waste Management and Valorization Pathways

by Sagar Kafle, Bhesh Kumar Karki, Manish Sakhakarmy and Sushil Adhikari

Recycling 2025, 10(3), 113; https://doi.org/10.3390/recycling10030113 - 6 Jun 2025

Viewed by 530

Abstract

Municipal solid waste (MSW) is rising globally, and improper management harms the environment and public health. As a result, there is heightened interest in finding effective solutions, and identifying research trends helps determine the best management and valorization pathways. However, the existing reviews [...] Read more.

Municipal solid waste (MSW) is rising globally, and improper management harms the environment and public health. As a result, there is heightened interest in finding effective solutions, and identifying research trends helps determine the best management and valorization pathways. However, the existing reviews often focus narrowly on specific technologies or regional case studies, lacking a comprehensive analysis of global research trends. This study addresses this significant gap by conducting a large-scale trend analysis based on 15,646 relevant articles screened from 25,068 Scopus-indexed publications from 1904 to 2023 using title, abstract, and keyword analysis. Literature-based comparative assessments were conducted to critically evaluate the pathways through TEE (techno-economic and environmental), SWOT (strengths, weaknesses, opportunities, and threats), and PESTEL (political, economic, social, technological, environmental, and legal) frameworks. Since 1990, article publication has increased by about 10% annually, consistently concentrating on thermochemical conversion and, more recently, on sustainability and circular economy perspectives. Seven distinct pathways for MSW management were identified, with recycling and material recovery, followed by thermochemical conversion for high-calorific waste and biochemical conversion for high-organic waste, showing the most promise. The findings aim to help researchers understand MSW research trends and assist planners in identifying effective management and valorization strategies. Full article

(This article belongs to the Topic Advances and Innovations in Waste Management)

► Show Figures

Figure 1

28 pages, 2017 KiB

Open AccessArticle

Valorization Diagnosis of Roasted Pyrite Ashes Wastes from the Iberian Pyrite Belt

by Juan Antonio Ramírez-Pérez, Manuel Jesús Gázquez-González and Juan Pedro Bolívar

Recycling 2025, 10(3), 112; https://doi.org/10.3390/recycling10030112 - 4 Jun 2025

Viewed by 329

Abstract

The Iberian Pyrite Belt (IPB) contains the world’s largest massive sulfide deposit, and, due to extensive mining developed during the last 200 years, large amounts of mining waste have been abandoned in this area, with roasted pyrite ash being the focus of this [...] Read more.

The Iberian Pyrite Belt (IPB) contains the world’s largest massive sulfide deposit, and, due to extensive mining developed during the last 200 years, large amounts of mining waste have been abandoned in this area, with roasted pyrite ash being the focus of this study. Polymetallic mining is also classified as a NORM (naturally occurring radioactive material) activity, thus the main objective of this work was to develop a radiological and physicochemical characterization of this waste (mineral phases, elemental and radionuclide concentrations) in order to perform a valorization diagnosis of this material. The composition of this waste strongly depends on its origin (mine), and is mainly formed by iron oxides (hematite, Fe₂O₃) and heavy metals and metalloids such as As, Pb, Zn, and Cu, in levels 2–4 orders of magnitude higher than those of undisturbed soils, depending on each particular element. However, the average natural radionuclide levels are similar to those of unperturbed soils (around 30 Bqkg⁻¹ of ²³⁸U-series, 50 Bqkg⁻¹ of ²³²Th, and 70 Bqkg⁻¹ for ⁴⁰K), thus they are below the limits established by European Union regulations to require radiological control during their future valorization. As the main potential applications of roasted pyrite ash, the valorization diagnosis indicates that it can be used as a source of Fe (FeCl₃ or FeSO₄), or an additive in the manufacturing of cements, pigments, etc. Full article

► Show Figures

Figure 1

19 pages, 1069 KiB

Open AccessArticle

Sustainable Consumer Behavior: Identifying Behavior Change Stages in Recycling in the USA

by Jing Jian Xiao and Feihong Xia

Recycling 2025, 10(3), 111; https://doi.org/10.3390/recycling10030111 - 3 Jun 2025

Viewed by 162

Abstract

Sustainable consumer behavior refers to any behavior that benefits environmental protection and social justice. Previous research has shown that sustainable consumer behavior is positively associated with consumer wellbeing. Recycling behavior is a type of sustainable behavior that has been studied extensively. However, research [...] Read more.

Sustainable consumer behavior refers to any behavior that benefits environmental protection and social justice. Previous research has shown that sustainable consumer behavior is positively associated with consumer wellbeing. Recycling behavior is a type of sustainable behavior that has been studied extensively. However, research on behavior change in recycling is limited. The purpose of this study is to identify the change stages for recycling behavior among American consumers. Using national data collected in the U.S. and under the guidance of the transtheoretical model of behavior change (TTM), the results showed that most Americans engage in recycling behavior, but a minority of them do not. Among them, 13% have never considered recycling in the near future. We also identified the differences in behavior change stages in terms of psychological, cognitive, socioeconomic, and environmental factors. The findings have implications for policy makers, business professionals, and consumer educators to develop strategies to encourage consumer recycling behavior. Full article

► Show Figures

Figure 1

13 pages, 7492 KiB

Open AccessArticle

Hydrothermal Extraction of Cellulose from Sugarcane Bagasse for Production of Biodegradable Food Containers

by Adisak Jaturapiree, Thanunya Saowapark, Kanjarat Sukrat and Ekrachan Chaichana

Recycling 2025, 10(3), 110; https://doi.org/10.3390/recycling10030110 - 1 Jun 2025

Viewed by 220

Abstract

Sugarcane bagasse (SCB), an organic waste generated during sugar and ethanol production, is a potential biomass source with a high cellulose content. In this study, cellulose was extracted from SCB using a hydrothermal method with various types of solvents, following which the extracted [...] Read more.

Sugarcane bagasse (SCB), an organic waste generated during sugar and ethanol production, is a potential biomass source with a high cellulose content. In this study, cellulose was extracted from SCB using a hydrothermal method with various types of solvents, following which the extracted materials were used for food container production. An alkali solvent—sodium hydroxide (NaOH)—and organic acids—citric acid and formic acid—were included as extractive solvents at two different concentrations (0.25 M and 2.0 M). Hydrothermal extraction with the alkali solvent demonstrated higher cellulose extraction abilities (67.7–74.0%) than those with the acids (52.5–57.3%). Using a low alkali concentration in the hydrothermal extraction (H-NaOH_low) demonstrated a cellulose extraction ability near that when using a high alkali concentration in the conventional boiling method (B-NaOH_high): 67.7% and 70.5%, respectively. Moreover, cellulose extracted with H-NaOH_low had better mechanical properties than that from B-NaOH_high, likely due to fewer defective fibers in the former. A high alkali concentration led to vigorous reactions that damaged the cellulose fibers. Thus, hydrothermal extraction has the benefit of using fewer chemicals, leading to a lower environmental impact. In addition, H-NaOH_low fibers were employed for food container production, and it was found that the obtained product has excellent properties, comparable to those of commercial containers. Full article

► Show Figures

Figure 1

18 pages, 2566 KiB

Open AccessArticle

Potential of Natural Sheep Casings Waste as a Sole Nitrogen Source for the Marine Microalga Scenedesmus rubescens MDP19 Growth and Lipid Production

by Sanaa Ouzakar, Nadia Skali Senhaji, Francesca Rigano, Cinzia Cafarella, Francesco Cacciola, Luigi Mondello and Jamal Abrini

Recycling 2025, 10(3), 109; https://doi.org/10.3390/recycling10030109 - 1 Jun 2025

Viewed by 241

Abstract

The meat industry is one of the main sources of organic waste in the food processing sector. Due to their high content of biodegradable organic matter, these wastes represent a potentially valuable resource for the development of recycling and valorization processes, particularly with [...] Read more.

The meat industry is one of the main sources of organic waste in the food processing sector. Due to their high content of biodegradable organic matter, these wastes represent a potentially valuable resource for the development of recycling and valorization processes, particularly with regard to the circular economy and environmental sustainability. The present study aimed at assessing the potential of natural sheep casings waste (NSCW) as a source of nitrogen for promoting the growth and lipid production of Scenedesmus rubescens MDP19, a marine microalga isolated from the Mediterranean coastline of northern Morocco. For this purpose, we evaluated the effects of different NSCW concentrations (0.25–5 g L⁻¹) on the microalga growth, its ability to utilize organic waste components (proteins, amino acids, and carbohydrates) as nutrients, and its efficiency in eliminating nitrogen and phosphorus. Lipid and pigment contents were determined using colorimetric methods, and their composition was analyzed by high-performance liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometry (HPLC-APCI-MS/MS). The results showed that S. rubescens MDP19 achieved the highest biomass production of 1.737 g L⁻¹ at an NSCW concentration of 5 g L⁻¹. This strain removed 33.70–47.63% of protein, 71.84–87.62% of amino acids, 41.9–92.97% of carbohydrates, 59.72–99.30% of nitrogen, and 80.74–99.10% of phosphorus. Furthermore, S. rubescens MDP19 showed a significantly enhanced lipid content (68.11%) at an NSCW concentration of 0.5 g L⁻¹. At this concentration, the lipid composition of S. rubescens MDP19 was particularly complex, including monounsaturated and polyunsaturated fatty acids, digalactosyldiacylglycerols, sulfoquinovosyldiacylglycerols, phosphatidylglycerols, and acylglycerols. The pigment profile includes neoxanthin, canthaxanthin, lutein, chlorophyll a, geranylgeranyl chlorophyll a, chlorophyllide b, hydrochlorophyllide b, and pheophytin a. These results indicate that natural sheep casings waste represents a promising source of nitrogen, reducing the need for nutrient supplementation in microalgae production. This approach not only offers a sustainable and economical alternative for optimizing microalgae cultivation but also contributes to the valorization of organic waste, thus supporting more ecological and responsible practices. Full article

(This article belongs to the Topic The Role of Microorganisms in Waste Treatment)

► Show Figures

Figure 1

20 pages, 4139 KiB

Open AccessArticle

Impact of Recycled Concrete and Ceramic Fillers on the Performance of Cementitious Systems: Microstructural, Mechanical, and Durability Aspects

by Tianjun Han, Diego Aponte, Susana Valls and Marilda Barra Bizinotto

Recycling 2025, 10(3), 108; https://doi.org/10.3390/recycling10030108 - 1 Jun 2025

Viewed by 235

Abstract

Cement production is a major contributor to CO₂ emissions, while construction and demolition waste (CDW) presents growing environmental challenges. The new European standard UNE-EN 197-6 permits the use of recycled concrete fines as partial clinker replacements, providing a regulatory framework for integrating [...] Read more.

Cement production is a major contributor to CO₂ emissions, while construction and demolition waste (CDW) presents growing environmental challenges. The new European standard UNE-EN 197-6 permits the use of recycled concrete fines as partial clinker replacements, providing a regulatory framework for integrating CDW into cementitious systems. This study investigates two CDW-derived fillers, FHH (recycled concrete filler) and FHC (recycled ceramic–concrete mixed filler), as partial substitutes for ordinary Portland cement (OPC). The materials were characterized using XRD, XRF, FTIR, and particle size analysis. Cement pastes and mortars with 10%, 20%, and 30% volume replacements were evaluated for hydration behavior, mechanical performance, and durability. At lower replacement levels, FHC promoted ettringite formation and microstructural refinement, while FHH favored carbonate hydrate development; both fillers also exhibited durability comparable to the control. At higher levels, they maintained satisfactory compressive strength. This study offers critical insights into the integration of CDW-derived fillers into cementitious systems, revealing their potential to significantly reduce clinker consumption while maintaining high mechanical and durability standards. Full article

► Show Figures

Figure 1

16 pages, 5906 KiB

Open AccessArticle

Research into Efficient Technology for Material Recovery of Waste Polyurethane Foams

by Ľubomír Šooš, Miloš Matúš, Stanislaw Legutko and Jozef Bábics

Recycling 2025, 10(3), 107; https://doi.org/10.3390/recycling10030107 - 1 Jun 2025

Viewed by 221

Abstract

The recovery of waste from old vehicles generates different types of waste. Most waste can be recovered with more or less success. Among the wastes that are problematic is foam. It is large in volume and light in weight, and there is currently [...] Read more.

The recovery of waste from old vehicles generates different types of waste. Most waste can be recovered with more or less success. Among the wastes that are problematic is foam. It is large in volume and light in weight, and there is currently no highly efficient technology to recover this waste and produce new products. The aim of this paper is to analyse the current situation in the processing, research, development, design and testing of test samples as a basis for the production of a machine to produce new 3D products made from waste foam. The paper begins with an analysis of the amount of plastic waste generated in the automotive industry. It describes the current state of waste management and the possibilities of its use in the production of new products. The core of the paper is the selection of suitable technology and the design and verification of experimental measurement and evaluation of test samples at different temperatures and pressures and with different endurance times. Full article

(This article belongs to the Special Issue Challenges and Opportunities in Plastic Waste Management)

► Show Figures

Figure 1

17 pages, 10015 KiB

Open AccessArticle

Combined Frozen Crystallization and Stepwise Decompression Evaporation for Na₂SO₄/NaCl Separation from Mixed Salts

by Chuqi Wang, Xinyu Huang, Hao Wang, Rui Chen and Xiuxiu Ruan

Recycling 2025, 10(3), 106; https://doi.org/10.3390/recycling10030106 - 1 Jun 2025

Viewed by 179

Abstract

Rapid industrialization has led to a substantial increase in waste salts containing Na₂SO₄/NaCl mixtures, posing significant challenges for their phase separation and resource recovery. This study pioneers an integrated process combining frozen crystallization with stepwise decompression evaporation for Na [...] Read more.

Rapid industrialization has led to a substantial increase in waste salts containing Na₂SO₄/NaCl mixtures, posing significant challenges for their phase separation and resource recovery. This study pioneers an integrated process combining frozen crystallization with stepwise decompression evaporation for Na₂SO₄/NaCl separation. Through the systematic investigation of phase transition behaviors under varying ionic ratios, the optimal combined processes corresponding to mixed salts with different compositions were identified. The experimental results demonstrate that brines with NaCl > 80.0% should preferentially undergo vacuum evaporation, while those below this threshold are suitable for prioritizing frozen crystallization for Na₂SO₄ recovery. Utilizing the complementary advantages of both processes, the mixture was prepared with a mass ratio of NaCl to Na₂SO₄ of 3:1. The frozen crystallization of the brine yielded 90.0% pure Na₂SO₄ crystals while concentrating NaCl to 92.0% in the residual liquor. Subsequent stepwise evaporation yielded 98.5% pure NaCl crystals. Finally, the removal effect and lifecycle evaluation of the process for impurity ions provide new insights for the zero liquid discharge system in industrial waste salt management. Full article

► Show Figures

Figure 1

22 pages, 7139 KiB

Open AccessArticle

Alkaline Solvothermal Debromination of Commercial Brominated Polystyrene

by Mario Ferreiro González, Fernanda Cabañas Gac and Gregory S. Patience

Recycling 2025, 10(3), 105; https://doi.org/10.3390/recycling10030105 - 1 Jun 2025

Viewed by 250

Abstract

Government regulations have required consumer products—electrical and electronic components, toys, furniture, clothing, and cars— to meet ever-increasing flame resistance standards, and industry has met these norms by adding brominated fire retardants. However, end-of-life treatment and up-cycling of these plastics is challenging as the [...] Read more.

Government regulations have required consumer products—electrical and electronic components, toys, furniture, clothing, and cars— to meet ever-increasing flame resistance standards, and industry has met these norms by adding brominated fire retardants. However, end-of-life treatment and up-cycling of these plastics is challenging as the brominated compounds are endocrine disruptors, bioaccumulators, and persist in the environment. Pyrolysis, catalytic cracking, or combustion, to recover its fuel value, produces toxic brominated dibenzodioxins and dibenzofurans Here, we demonstrated the efficacy of a solvothermal treatment that extracts up to 99% of the bromine from high-impact polystyrene (HIPS) and polystyrene (PS) in electrical and electronic waste (e-waste). The process operated between 160 °C and 230 °C with ethylene glycol or triethylene glycol as the solvent and NaOH or KOH as the extraction agent (0.5 M to 2 M). The reaction rates depended on the particle size: 60 mm plastic chunks took up to between 4 and 24 h to react while fibers 3 mm in diameter reacted in less than 5 min. Full article

(This article belongs to the Special Issue Challenges and Opportunities in Plastic Waste Management)

► Show Figures

Figure 1

10 pages, 3953 KiB

Open AccessArticle

An Innovative Approach for Delamination of Solar Panels Using a Heated Metal Wire

by Mihail Zagorski, Konstantin Dimitrov, Valentin Kamburov, Antonio Nikolov, Kostadin Stoichkov and Yana Stoyanova

Recycling 2025, 10(3), 104; https://doi.org/10.3390/recycling10030104 - 22 May 2025

Viewed by 386

Abstract

Over the last two decades, the use of photovoltaic panels for the production of electricity has increased significantly, which leads to the need to solve the problems concerning the decommissioning and disposal of the panels and the development of appropriate technologies for their [...] Read more.

Over the last two decades, the use of photovoltaic panels for the production of electricity has increased significantly, which leads to the need to solve the problems concerning the decommissioning and disposal of the panels and the development of appropriate technologies for their recycling. One of the key steps in this process is the separation of the tempered glass layer. Various technologies and devices are known for separating the glass of the solar panel by cutting it with a knife, as well as other instruments, with the different methods being based on mechanical, chemical, and thermal processes and accordingly having their own advantages and disadvantages. This article proposes an innovative approach for the mechanical delamination of solar panels using a metal wire heated by Joule heating, with the potential to become an energy-efficient, economical, and environmentally friendly method. This publication presents results from experiments using this type of tool to separate the layers of solar panels. Photos from a thermal camera are presented, showing the heat distribution in the panel and the reached operating temperature of the heated metal wire, necessary to soften the EVA bonding layer. Full article

► Show Figures

Figure 1

19 pages, 449 KiB

Open AccessArticle

Understanding Demographic and Behavioral Determinants of Engagement in Plastic Tableware Reduction: Behavior, Support, and Price Sensitivity

by Sai-Leung Ng and Yu-Chieh Hsieh

Recycling 2025, 10(3), 103; https://doi.org/10.3390/recycling10030103 - 20 May 2025

Viewed by 208

Abstract

Plastic waste reduction has become a global priority, with consumer engagement playing a crucial role in the success of sustainability initiatives. This study examines the demographic and behavioral determinants of consumer engagement in plastic tableware reduction. Using survey data from Hong Kong residents [...] Read more.

Plastic waste reduction has become a global priority, with consumer engagement playing a crucial role in the success of sustainability initiatives. This study examines the demographic and behavioral determinants of consumer engagement in plastic tableware reduction. Using survey data from Hong Kong residents and a Multivariate Analysis of Variance (MANOVA) approach, this study analyzes how age, gender, education, income, housing type, order frequency, opt-out effectiveness, and their interactions influence the four dimensions of engagement, namely plastic tableware opt-out behavior, support for government policies, support for plastic-free restaurants, and price sensitivity. The results indicate that age significantly affects plastic tableware reduction engagement, with order frequency and opt-out effectiveness moderating the effects of age and education. The study contributes to the literature by providing empirical insights into consumer-driven sustainability efforts and the role of behavioral factors in shaping engagement in plastic waste reduction. These findings offer valuable implications for policymakers and businesses promoting sustainable consumption practices. Full article

► Show Figures

Figure 1

20 pages, 2880 KiB

Open AccessArticle

Measuring the Impact of Education on Waste Streams from Multi-Family Housing

by Dhanush Kenchanna, Tina Marie Waliczek and Xiangping Liu

Recycling 2025, 10(3), 102; https://doi.org/10.3390/recycling10030102 - 19 May 2025

Viewed by 276

Abstract

Food waste is a significant global issue with substantial environmental, economic, and social implications. This exploratory study aimed to evaluate the impact of an educational composting program on reducing food waste generation and promoting proper waste sorting practices within multi-family housing units in [...] Read more.

Food waste is a significant global issue with substantial environmental, economic, and social implications. This exploratory study aimed to evaluate the impact of an educational composting program on reducing food waste generation and promoting proper waste sorting practices within multi-family housing units in San Marcos, Texas. A comprehensive methodology was employed, encompassing pre- and post-intervention waste audits, educational interventions, weekly organic waste collection, and quantitative data analyses. Nine multi-family complexes, spanning student housing, conventional family units, low-income residences, and senior living facilities, were targeted through strategic recruitment efforts and incentivization. The treatment group, consisting of 43 participants, received ongoing education throughout the eight-week implementation period, facilitated through informational resources, feedback mechanisms, and door-to-door organic waste collection. Conversely, the control group did not partake in the educational component. Statistical analyses, including descriptive statistics and paired t-tests, facilitated comparisons across various dimensions, such as housing types, treatment versus control groups, and pre- versus post-intervention periods. The findings revealed significant reductions in organic waste and compostable materials within the treatment group’s weekly landfill trash, underscoring the effectiveness of the educational program. Furthermore, insights into contamination patterns and housing-specific waste characteristics were garnered, informing targeted intervention strategies and policy recommendations for optimizing multi-family composting initiatives. Full article

► Show Figures

Graphical abstract

16 pages, 1164 KiB

Open AccessArticle

Value Extraction from End-of-Life Textile Products in Pakistan

by Muhammad Waqas Iqbal, Muhammad Babar Ramzan, Haleema Manzoor and Sheheryar Mohsin Qureshi

Recycling 2025, 10(3), 101; https://doi.org/10.3390/recycling10030101 - 19 May 2025

Viewed by 316

Abstract

Overconsumption and unplanned disposal of garments result in millions of tons of textile products going to landfills. Understanding the environmental benefits and impact of various recycling options is crucial for integrating recycling into the apparel waste stream. This study aims to assess the [...] Read more.

Overconsumption and unplanned disposal of garments result in millions of tons of textile products going to landfills. Understanding the environmental benefits and impact of various recycling options is crucial for integrating recycling into the apparel waste stream. This study aims to assess the environmental impacts of products made from post-consumer textile waste fibers, highlighting the importance of closed-loop textile supply chains in developing countries. Using Open LCA software, the cradle-to-gate approach for life cycle assessment is used to calculate the environmental impacts of post-consumer textile waste, virgin cotton, virgin polyester fibers, and their blends in two different scenarios. The life cycle inventory data for functional units (1000 kg apparel) has been collected from the industrial units and the Ecoinvent v3.0 database. The results of 16 environmental impact categories are computed, showing that textile products made from virgin cotton fiber have 60% more global warming potential than those made from post-consumer textile waste fibers. Hence, the environmental impact of textile products can be controlled by recycling them. Consumption of post-consumer textile waste fiber is the key to reducing the new material needs in the textile supply chain. The closed-loop apparel supply chain can help developing countries generate maximum financial value with minimal environmental damage. In developing countries, value extraction from post-consumer textile waste recycling is essential to meet international consumer demands for cleaner production. Full article

► Show Figures

Figure 1

32 pages, 1460 KiB

Open AccessArticle

Evaluating Recycling Initiatives for Landfill Diversion in Developing Economies Using Integrated Machine Learning Techniques

by Muyiwa Lawrence Adedara, Ridwan Taiwo, Olusola Olaitan Ayeleru and Hans-Rudolf Bork

Recycling 2025, 10(3), 100; https://doi.org/10.3390/recycling10030100 - 19 May 2025

Viewed by 346

Abstract

This study investigates the effectiveness of the Lagos Recycle Initiative (LRI) on landfill diversion (LFD) in Lagos, Nigeria, where evidence-based assessments of such initiatives are lacking. It evaluates the recycling diversion rate (RDR) of household recyclables (HSRs) across local government areas using field [...] Read more.

This study investigates the effectiveness of the Lagos Recycle Initiative (LRI) on landfill diversion (LFD) in Lagos, Nigeria, where evidence-based assessments of such initiatives are lacking. It evaluates the recycling diversion rate (RDR) of household recyclables (HSRs) across local government areas using field surveys and population data. Machine learning algorithms (logistic regression, random forest, XGBoost, and CatBoost) refined with Bayesian optimisation were employed to predict household recycling motivation. The findings reveal a low RDR of 0.37%, indicating that only approximately 2.47% (31,554.25 metric tonnes) of recyclables are recovered annually compared to a targeted 50% (638,750 metric tonnes). The optimised CatBoost model (accuracy and F1 score of 0.79) identified collection time and the absence of overflowing HSR bins as key motivators for household recycling via the SHapley Additive exPlanations (SHAP) framework. This study concludes that current LRI efforts are insufficient to meet recycling targets. It recommends expanding recovery efforts and addressing operational challenges faced by registered recyclers to improve recycling outcomes. The policy implications of this study suggest the need for stricter enforcement of recycling regulations, coupled with targeted financial incentives for both recyclers and households to boost recycling participation, thereby enhancing the overall effectiveness of waste diversion efforts under the LRI. This research provides a benchmark for assessing urban recycling initiatives (RIs) in rapidly growing African cities. Full article

► Show Figures

Figure 1

31 pages, 6141 KiB

Open AccessArticle

Fe₃O₄/SiO₂ Nanocomposite Derived from Coal Fly Ash and Acid Mine Drainage for the Adsorptive Removal of Diclofenac in Wastewater

by Dance Mabu, Ngwako Joseas Waleng, Tshimangadzo S. Munonde, Azile Nqombolo and Philiswa Nosizo Nomngongo

Recycling 2025, 10(3), 99; https://doi.org/10.3390/recycling10030099 - 16 May 2025

Viewed by 200

Abstract

The ubiquity of diclofenac (DCF) in the environment has raised significant concerns. Diclofenac is a non-steroidal anti-inflammatory drug that has been found in various environmental matrices at minimum concentrations that are harmful to aquatic and terrestrial organisms. Traditional wastewater treatment plants (WWTPs) are [...] Read more.

The ubiquity of diclofenac (DCF) in the environment has raised significant concerns. Diclofenac is a non-steroidal anti-inflammatory drug that has been found in various environmental matrices at minimum concentrations that are harmful to aquatic and terrestrial organisms. Traditional wastewater treatment plants (WWTPs) are not fully equipped to remove a range of pharmaceuticals, and that explains the continued ubiquity of DCF in surface waters. In this study, an Fe₃O₄/SiO₂ nanocomposite prepared from acid mine drainage and coal fly ash was applied for the removal of DCF from wastewater. Major functional groups (Si–O–Si and Fe–O) were discovered from FTIR. TEM revealed uniform SiO₂ nanoparticle rod-like structures with embedded dark spherical nanoparticles. SEM-EDS analysis discovered a sponge-like structure fused with Fe₃O₄ nanoparticles that had significant Si, O, and Fe content. XRD demonstrated the crystalline nature of the nanocomposite. The surface properties of the nanocomposite were evaluated using BET and were 67.8 m²/g, 0.39 cm³/g, and 23.2 nm for surface area, pore volume, and pore size, respectively. Parameters that were suspected to be affecting the removal process were evaluated, including pH, nanocomposite dosage, and sample volume. The detection of DCF was conducted on high-performance liquid chromatography with diode-array detection (HPLC-DAD). Under optimum conditions, the adsorption process was monolayer, and physisorption was described using the Langmuir and Dubinin-Radushkevich (D-R) isotherm models. The kinetic data best fitted the pseudo-first order kinetic model, indicating a physisorption adsorption process. The thermodynamic experimental data confirmed that the adsorption process was spontaneous. The results obtained from real water samples showed 95.28% and 97.44% removal efficiencies from influent and effluent: 94.83% and 88.61% from raw sewage and final sewage, respectively. Overall, this work demonstrated that an Fe₃O₄/SiO₂ nanocomposite could be successfully prepared from coal fly ash and acid mine drainage and could be used to remove DCF in wastewater. Full article

► Show Figures

Figure 1

19 pages, 2682 KiB

Open AccessArticle

Life Cycle Assessment of Recycling Polyethylene Terephthalate (PET): A Comparative Case Study in Taiwan

by Allen H. Hu, Chih-Yu Ting, Ali Ouattara, Wei-Tse Chen and Chien-Hung Kuo

Recycling 2025, 10(3), 98; https://doi.org/10.3390/recycling10030098 - 16 May 2025

Viewed by 566

Abstract

Polyethylene terephthalate (PET) is commonly used in beverage container manufacturing; however, its classification as a single-use plastic significantly contributes to environmental pollution. Improper disposal results in enduring contamination of both terrestrial and marine ecosystems, which poses ecological and health risks. Among the disposal [...] Read more.

Polyethylene terephthalate (PET) is commonly used in beverage container manufacturing; however, its classification as a single-use plastic significantly contributes to environmental pollution. Improper disposal results in enduring contamination of both terrestrial and marine ecosystems, which poses ecological and health risks. Among the disposal methods, recycling, incineration, and landfilling, only recycling promotes a circular economy by reducing reliance on landfills, alleviating emissions, and conserving fossil resources. This study employs the life cycle assessment (LCA) method to evaluate the environmental impacts of three PET bottle recycling facilities in Taiwan, considering collection, transportation, and processing in the system boundary. It also assesses the effects of raw material composition, comparing transparent, colored, and mixed PET bottles. The results indicate that facilities processing colorless PET have lower environmental damage values (16.6–18.1 mPt·kg⁻¹ of recycled flakes) than those handling colored and oil-trapped PET (25 mPt·kg⁻¹) due to higher energy demands and poly aluminum chloride usage in wastewater treatment. Granulation was identified as a significant environmental hotspot for recycled PET pellets, with a damage value of 35 mPt·kg⁻¹. Integrating renewable energy and recycled PET into PET bottle manufacturing could significantly reduce their environmental impacts. Policy recommendations include adopting renewable energies as the source energy, calibrating the use of chemicals in recycling facilities, and mandating minimum recycled content in PET products to enhance circularity. Full article

(This article belongs to the Special Issue Challenges and Opportunities in Plastic Waste Management)

► Show Figures

Figure 1

24 pages, 13260 KiB

Open AccessArticle

Upcycling of Cupric Chloride Waste Solution from PCB Manufacturing for Antibacterial Copper Nanoparticles

by Tapany Patcharawit, Chatisa Kansomket, Napat Mahiwan, Sumita Chailoi, Thanapon Chandakhiaw, Tanongsak Yingnakorn, Teerawut Tunnukij and Sakhob Khumkoa

Recycling 2025, 10(3), 97; https://doi.org/10.3390/recycling10030097 - 14 May 2025

Viewed by 312

Abstract

Issues encompassing hazardous waste management face challenges, particularly those involving the manufacture of electronic devices such as PCBs that are in high demand with continual growth. Therefore, upcycling to create new products viable for highly valued markets emphasizes alternative solutions towards the circular [...] Read more.

Issues encompassing hazardous waste management face challenges, particularly those involving the manufacture of electronic devices such as PCBs that are in high demand with continual growth. Therefore, upcycling to create new products viable for highly valued markets emphasizes alternative solutions towards the circular economy. This research highlights the advantages of copper sulfate recovery from the cupric chloride etching waste solution from PCB manufacturing, combined with the synthesis of copper nanoparticles for antibacterial application. First, aluminium cementation, sulfuric acid leaching, and crystallization were incorporated in the recovery step to ensure a high purity of 99.95% and a recovery of 94.76%. Aluminium cementation selectively offered copper-containing precipitates suitable for leaching to gain high-purity recovered products. In the second step, copper nanoparticles were synthesized using 0.01–0.20 M copper sulfate precursors via sonochemical reduction. In total, 1–5 mL of hydrazine and 5–30 mL of 0.01 M ethylene glycol were added into a 50 mL precursor as reducing and capping agents, respectively. Hydrazine addition under high pH played a key role in controlling the shape, size, and purity of the copper nanoparticles, required for their antibacterial properties. The optimum condition gave spherical or polygonal copper nanoparticles of 54.54 nm at 99.95% purity and >92% recovery. The antibacterial test of the synthesized copper nanoparticles using E. coli via agar well diffusion exhibited a zone of inhibition (ZOI) of 50 mm at 127 mg/mL, similar to the antibiotic-controlled condition, proving their antibacterial potential. Along with process effectiveness, a feasibility study of the inventing process confirmed the environmental and economic impacts of minimizing energy consumption and processing time, which are competitive with respect to the existing recycling technologies. Full article

► Show Figures

Graphical abstract

37 pages, 6715 KiB

Open AccessArticle

Barriers to Mainstream Adoption of Circular Packaging in Indonesia

by Nazlı Terzioğlu, Fabrizio Ceschin, Yulianti Pratama, Emenda Sembiring and Susan Jobling

Recycling 2025, 10(3), 96; https://doi.org/10.3390/recycling10030096 - 13 May 2025

Viewed by 416

Abstract

Achieving the mainstream adoption of circular packaging is essential for mitigating the environmental impacts of plastic waste. Its widespread adoption, however, remains hindered by significant user barriers. This study investigates the barriers to user adoption of upstream packaging solutions in Indonesia with the [...] Read more.

Achieving the mainstream adoption of circular packaging is essential for mitigating the environmental impacts of plastic waste. Its widespread adoption, however, remains hindered by significant user barriers. This study investigates the barriers to user adoption of upstream packaging solutions in Indonesia with the aim of reducing plastic packaging waste. Through a mixed-methods approach including case studies, expert workshops, and focus group discussions, nine key barriers were identified and analysed. These include inconvenience, resistance to changing habits and behaviours, higher costs and deposit schemes, contamination and hygiene concerns, wear and tear, functional and performance limitations, a lack of awareness about the environmental impacts, limited availability and variety, and a lack of trust. This research advances the literature by offering a detailed analysis of these barriers, categorising them into sociocultural, economic, contextual, and regulatory aspects. Additionally, barriers specific to Indonesia were identified such as a shift from being served to self-service refilling, some people not having smartphones, poor cellular signals in rural areas, a preference for plastic packaging due to its resale value, and a preference for cash payments due to limited access to credit or bank cards. The findings highlight the need for tailored, multidisciplinary strategies to overcome these barriers and promote the adoption of circular packaging solutions. This research provides valuable insights for researchers studying circular design, businesses seeking to innovate upstream packaging solutions, and policymakers aiming to develop regulations that support the adoption of circular packaging practices. Full article

► Show Figures

Figure 1

15 pages, 3312 KiB

Open AccessArticle

Recycling of Poly(Propylene) Based Car Bumpers in the Perspective of Polyolefin Nanoclay Composite Film Production

by Nemr El Hajj, Sylvain Seif and Nancy Zgheib

Recycling 2025, 10(3), 95; https://doi.org/10.3390/recycling10030095 - 10 May 2025

Viewed by 365

Abstract

This study uses the melt compounding method to recycle polypropylene-based car bumper waste (PP-CBW) in order to produce nanocomposite films for mulch application. The nanocomposite films were compounded by mixing virgin linear low-density polyethylene (LLDPE) with PP-CBW at a constant ratio of 4:1 [...] Read more.

This study uses the melt compounding method to recycle polypropylene-based car bumper waste (PP-CBW) in order to produce nanocomposite films for mulch application. The nanocomposite films were compounded by mixing virgin linear low-density polyethylene (LLDPE) with PP-CBW at a constant ratio of 4:1 in the presence of different percentages of nanofillers. Nanocomposites reinforced with nanoclays were compatibilized with an anhydride grafted polyethylene (PE-g-MAH), at a constant compatibilizer-to-clay ratio equal to 3, to improve the adherence between the nonpolar matrix and the hydrophilic nanoclay and acrylic paint present in the car bumper. An extruder with a corotating twin screw was used to produce blends of different compositions. To create nanocomposite films, the mixtures were further processed in a blown film extruder. The effect of the presence of nanoclays on the barrier, thermal, and mechanical properties of the nanocomposite films was investigated. The dispersion of clay layers in the matrix was examined by atomic force microscopy (AFM). The results indicate that 3 wt% of clay loading maximized the tensile strength in the transverse direction (TD) and machine direction (MD). A 1 wt% clay loading increased the MD tear resistance by 66% and manifested an optimum dart impact strength. Significant improvements in thermal and barrier properties were also achieved in the presence of 3 wt% clay loading. Full article

(This article belongs to the Special Issue Challenges and Opportunities in Plastic Waste Management)

► Show Figures

Graphical abstract

32 pages, 2154 KiB

Open AccessArticle

An Environmental and Economic Assessment of Household Food Waste Management Scenarios in Ireland

by Majid Bahramian, Courage Krah, Paul Hynds and Anushree Priyadarshini

Recycling 2025, 10(3), 94; https://doi.org/10.3390/recycling10030094 - 9 May 2025

Viewed by 416

Abstract

Effective management of household food waste (HFW) is essential for sustainability and aligning with Ireland’s waste reduction goals. This study evaluates the environmental and economic impacts of four HFW management scenarios—incineration, anaerobic digestion (AD) with digestate composting, AD with digestate incineration, and AD [...] Read more.

Effective management of household food waste (HFW) is essential for sustainability and aligning with Ireland’s waste reduction goals. This study evaluates the environmental and economic impacts of four HFW management scenarios—incineration, anaerobic digestion (AD) with digestate composting, AD with digestate incineration, and AD with digestate gasification—using life cycle assessment (LCA) and life cycle costing (LCC) analyses. The functional unit is 1000 tons of daily HFW treatment. The results show that AD scenarios offer significant environmental advantages over incineration, with AD combined with digestate composting identified as the most sustainable option. This scenario achieves the greatest reduction in greenhouse gas emissions and enhances nutrient recovery. Economically, while AD involves higher capital investments (€677,000–€2,033,000), its long-term cost effectiveness is demonstrated through LCCs ranging from €1,016,000 to €3,386,000, partially offset by revenues of €339,000–€677,000. The sensitivity analysis highlights opportunities for improvement, such as optimizing water use and reducing emissions from biogas engines. The findings provide actionable insights for policymakers, emphasizing the environmental and economic benefits of integrating AD with composting as a preferred strategy for HFW management. Full article

► Show Figures

Figure 1

19 pages, 6562 KiB

Open AccessArticle

Rethinking PE-HD Bottle Recycling—Impacts of Reducing Design Variety

by Lorenz P. Bichler, Thomas Koch, Nina Krempl and Vasiliki-Maria Archodoulaki

Recycling 2025, 10(3), 93; https://doi.org/10.3390/recycling10030093 - 8 May 2025

Viewed by 641

Abstract

As the severe environmental impacts of plastic pollution demand determined action, the European Union (EU) has included recycling at the core of its policies. Consequently, evolving jurisdiction now aims to achieve a recycling rate of 65% for non-PET plastic bottles by 2040. However, [...] Read more.

As the severe environmental impacts of plastic pollution demand determined action, the European Union (EU) has included recycling at the core of its policies. Consequently, evolving jurisdiction now aims to achieve a recycling rate of 65% for non-PET plastic bottles by 2040. However, the widespread use of post-consumer high-density polyethylene (rPE-HD) recyclates in household chemical containers is still limited by PP contamination, poor mechanical properties, and low environmental stress cracking resistance (ESCR). Although previous studies have explored the improvement of regranulate properties through additives, few have examined whether reducing the variety of extrusion blow-moulded PE-HD packaging could offer similar benefits. Therefore, two sorted fractions of rPE-HD hollow bodies were processed into regranulates under industrial conditions, including hot washing, extrusion, and deodorisation. Subsequently, both materials underwent comprehensive characterisation regarding their composition and performance. The opaque material, which was sourced from milk bottles in the UK, exhibited greater homogeneity with minor impurities, leading to improved ductility and melt strain hardening at moderate strain rates compared to the mixed material stream, which contained approximately 2.5% PP contamination. However, both rPE-HD recyclates exhibited similar short-term creep behaviour, relatively low strain hardening moduli, and were almost devoid of inorganic particles. Considering the sum of the investigated properties, melt blending with suitable virgin material is likely one of the most effective options to maximise regranulate utilisation in hollow bodies, followed by recycling-oriented packaging design (e.g., for efficient sorting), and the employment of advanced sorting technology. Full article

► Show Figures

Graphical abstract

20 pages, 4247 KiB

Open AccessArticle

Redispersibility of Paper Under Low Agitation and How It Deteriorates over Time

by Andrea Christine Pfennich and Ulrich Hirn

Recycling 2025, 10(3), 92; https://doi.org/10.3390/recycling10030092 - 6 May 2025

Viewed by 230

Abstract

In many paper applications the paper is supposed to disintegrate into its constituating fibers after disposal. This happens in water with only very little input of mechanical energy. The aim of this work is to understand the natural aging processes in different pulp [...] Read more.

In many paper applications the paper is supposed to disintegrate into its constituating fibers after disposal. This happens in water with only very little input of mechanical energy. The aim of this work is to understand the natural aging processes in different pulp types and their impact on the disintegration behavior under low agitation. We first introduce a laboratory testing method to assess the disintegration performance of various paper types in water under low mechanical energy input. Then we investigated the changes in paper disintegration and the corresponding physical properties over a nine-month period of paper storage. We measured wet strength, water retention value WRV, speed of water penetration, and contact angle. Our findings reveal substantial degradation of disintegration over time for unbleached paper. In contrast, for bleached paper the changes are much less pronounced. The best predictor of paper dispersibility turned out to be wet tensile strength. Furthermore, we found a strong relation between deterioration of dispersibility and fiber wetting (contact angle) and fiber swelling (WRV). We hence conclude that the observed decrease of low agitation paper dispersibility over time is related to a deteriorated water uptake into the fibers and fiber-fiber bonds which prevents the breaking of the bonds by the water. As potential aging mechanisms related to water uptake we identified hornification, crosslinking and lignin self-sizing as major factors influencing fiber-water interactions and ultimately the disintegration behavior. Full article

► Show Figures

Graphical abstract

9 pages, 2757 KiB

Open AccessArticle

Ergothioneine Circulation in Mushroom Cultivation Using Food Waste Recycling

by Ryota Kataoka, Ami Nigaki, Babla Shingha Barua and Ko Yamashita

Recycling 2025, 10(3), 91; https://doi.org/10.3390/recycling10030091 - 6 May 2025

Viewed by 343

Abstract

Current food production systems generate and incinerate significant amounts of organic waste, which increases costs and energy consumption. In this study, we show that food waste, including food loss, can be used for mushroom cultivation. We also developed a new mushroom culture medium [...] Read more.

Current food production systems generate and incinerate significant amounts of organic waste, which increases costs and energy consumption. In this study, we show that food waste, including food loss, can be used for mushroom cultivation. We also developed a new mushroom culture medium to replace conventional sawdust. Oyster mushrooms cultivated using food waste, including food loss, as the primary component contain higher levels of ergothioneine than that in the oyster mushrooms grown using sawdust, which has an antioxidant effect. We found that the proportion of nitrogen derived from animal protein in the mushroom culture medium influences ergothioneine content in fruiting bodies. We showed that irradiation with blue LEDs might produce mushrooms with a higher ergothioneine content than T-2 media. Furthermore, we established that ergothioneine is absorbed by the plant body. We aimed to develop an agricultural technology using food waste, including food loss, as growing media for mushrooms. Ultimately, we hope to create a regional cyclical food production system centered on mushroom cultivation, using food waste, including food loss, to promote microcirculation. Full article

► Show Figures

Figure 1

21 pages, 4436 KiB

Open AccessArticle

Sustainability and Innovation: Incorporating Waste from Ophthalmic Lenses into Natural Rubber Composites

by José Afonso Rocha, Carlos Toshiyuki Hiranobe, Dener da Silva Souza, Samara da Silva Araújo, Márcia Ferreira Hiranobe, Guilherme Henrique Barros de Souza, Elmer Mateus Gennaro, Flávio Camargo Cabrera, Guilherme Pina Cardim, Michael Jones da Silva, Erivaldo Antônio da Silva, José Francisco Resende da Silva and Renivaldo José dos Santos

Recycling 2025, 10(3), 90; https://doi.org/10.3390/recycling10030090 - 4 May 2025

Viewed by 359

Abstract

This study investigates the recycling of ophthalmic lens waste (OLW) in the production of vulcanized natural rubber (NR) composites, aiming to promote sustainability and reduce costs. To this end, Vietnamese natural rubber and ophthalmic lens waste were used, varying the filler content from [...] Read more.

This study investigates the recycling of ophthalmic lens waste (OLW) in the production of vulcanized natural rubber (NR) composites, aiming to promote sustainability and reduce costs. To this end, Vietnamese natural rubber and ophthalmic lens waste were used, varying the filler content from 0 to 50 phr. Rheological tests demonstrated that the addition of OLW decreases the cure time. The crosslink density, assessed through the Flory–Rehner and Mooney–Rivlin methods, exhibited an increase with the incorporation of a reinforcement. Thermal and spectroscopic analyses demonstrated the thermal stability of the composites and the absence of chemical interactions between the polymer matrix and the OLW. Mechanical tests showed that the composites exhibit satisfactory tensile and tear resistance, although the filler primarily acts as a filler rather than a structural reinforcement. Thus, the incorporation of OLW in NR composites emerges as a viable alternative for the reuse of industrial waste, fostering more sustainable and efficient practices in the polymer industry. Full article

(This article belongs to the Special Issue Challenges and Opportunities in Plastic Waste Management)

► Show Figures

Graphical abstract

18 pages, 4764 KiB

Open AccessArticle

Hydrothermal Carbonization of Biomass Waste for Solid Biofuel Production: Hydrochar Characterization and Its Application in Blast Furnace Injection

by Guangwei Wang, Junyi Wu, Haibo Li, Andrey Karasev, Xiaojun Ning and Chuan Wang

Recycling 2025, 10(3), 89; https://doi.org/10.3390/recycling10030089 - 4 May 2025

Viewed by 392

Abstract

Hydrothermal carbonization (HTC) technology converts biomass into a carbon-rich, oxygen-containing solid fuel. Most studies have focused on hydrochar produced under laboratory conditions, leaving a gap in understanding the performance of industrially produced hydrochar. This study comprehensively analyzes three types of industrially produced hydrochar [...] Read more.

Hydrothermal carbonization (HTC) technology converts biomass into a carbon-rich, oxygen-containing solid fuel. Most studies have focused on hydrochar produced under laboratory conditions, leaving a gap in understanding the performance of industrially produced hydrochar. This study comprehensively analyzes three types of industrially produced hydrochar for blast furnace (BF) injection. The results indicate that hydrochar has a higher volatile and lower fixed carbon content. It has a lower high heating value (HHV) than coal and contains more alkali matter. Nevertheless, hydrochar exhibits a better grindability and combustion performance than coal. Blending hydrochar with anthracite significantly enhances the combustion reactivity of the mixture. The theoretical conversion rate calculations reveal a synergistic effect between hydrochar and anthracite during co-combustion. Environmental benefit calculations show that replacing 40% of bituminous coal with hydrochar can reduce CO₂ emissions by approximately 145 kg/tHM, which is equivalent to an annual reduction of 528 kton of CO₂ and 208 kton of coal in BF operations. While industrially produced hydrochar meets BF injection requirements, its low ignition point and high explosivity necessitate the careful control of the blending ratio. Full article

(This article belongs to the Special Issue Biomass Revival: Rethinking Waste Recycling for a Greener Future)

► Show Figures

Figure 1

15 pages, 3012 KiB

Open AccessArticle

Efficient Extraction of Lithium, Cobalt, and Nickel from Nickel-Manganese-Cobalt Oxide Cathodes with Cholin Chloride/Pyrogallol-Based Deep Eutectic Solvent

by Aisulu Batkal, Kaster Kamunur, Lyazzat Mussapyrova, Yerzhan Mukanov and Rashid Nadirov

Recycling 2025, 10(3), 88; https://doi.org/10.3390/recycling10030088 - 3 May 2025

Viewed by 370

Abstract

This study explores the use of a deep eutectic solvent (DES) composed of choline chloride and pyrogallol (1:1 molar ratio) for the recovery of lithium, cobalt, and nickel from spent lithium-ion battery cathodes based on LiNi_0.33Co_0.33Mn_0.33O₂ [...] Read more.

This study explores the use of a deep eutectic solvent (DES) composed of choline chloride and pyrogallol (1:1 molar ratio) for the recovery of lithium, cobalt, and nickel from spent lithium-ion battery cathodes based on LiNi_0.33Co_0.33Mn_0.33O₂ (NMC111). The DES exhibits moderate viscosity, intrinsic redox activity, and strong complexation ability, enabling efficient metal dissolution under mild conditions. The effects of both temperature (50–80 °C) and time (up to 12 h) on leaching efficiency were systematically investigated. Optimal leaching parameters—80 °C, 8 h, and a liquid-to-solid ratio of 50—yielded extraction efficiencies of 92% for Li, 85% for Co, and 88% for Ni. Kinetic modeling indicated pseudo-first-order behavior with activation energies of 26.6, 22.1, and 25.2 kJ/mol for Li, Co, and Ni, respectively. Mechanistic analysis confirmed the dual role of pyrogallol as both reducing agent (facilitating Co³⁺ to Co²⁺ conversion) and chelating ligand. Full article

► Show Figures

Figure 1

24 pages, 1089 KiB

Open AccessReview

Bioleaching of Gold from Printed Circuit Boards: Potential Sustainability of Thiosulphate

by Zahra Ilkhani and Farid Aiouache

Recycling 2025, 10(3), 87; https://doi.org/10.3390/recycling10030087 - 3 May 2025

Viewed by 464

Abstract

The rapid consumption and disposal of electronic waste due to technological innovations and changes in living commodities are causing the development of a significant environmental challenge. Among the components of these wastes, spent printed circuit boards are particularly considered to be among the [...] Read more.

The rapid consumption and disposal of electronic waste due to technological innovations and changes in living commodities are causing the development of a significant environmental challenge. Among the components of these wastes, spent printed circuit boards are particularly considered to be among the most valuable owing to their content of precious metals, such as gold first and potentially platinum, which may be available in a lower proportion. Effective methods as part of gold recovery strategies by industries and policymakers are developed and envisioned from economic and environmental perspectives. Currently, cyanidation dominates global gold production from e-waste due to its selectivity for gold. The high toxicity of cyanide, however, poses serious environmental issues, leading thiosulphate leaching to emerge as a non-toxic and promising alternative for gold extraction. Its industrial viability has been demonstrated by Barrick Gold Corporation at the Goldstrike site with the pretreatment of acidic or alkaline pressure oxidation. This review introduces bioleaching as a promising economic and environmentally friendly process for gold extraction. This review explores thiosulphate leaching of gold as an alternative to conventional cyanidation, with a particular focus on biothiosulphate production by adapted microorganisms. The factors that affect the pretreatment, chemical reaction mechanism, and design engineering are discussed. The consumption of thiosulphate was identified as one of the main challenges, restricting the reliability of the process. Various solutions for the reduction of its consumption and relevant process costs were discussed, with a particular examination from the engineering aspect of the process design and scalability to industrially relevant operating conditions by using bioreactors adapted to large pulp density loads of electrical waste. Full article

(This article belongs to the Special Issue Emerging Technologies in the Hydrometallurgical Recycling of Critical Metals)

► Show Figures

Figure 1

22 pages, 15469 KiB

Open AccessArticle

Electrolytic Recovery of Indium from Copper Indium Gallium Selenide Photovoltaic Panels: Preliminary Investigation of Process Parameters

by Monika Gajec, Anna Król, Jadwiga Holewa-Rataj, Ewa Kukulska-Zając and Tomasz Kuchta

Recycling 2025, 10(3), 86; https://doi.org/10.3390/recycling10030086 - 2 May 2025

Viewed by 314

Abstract

The European Green Deal emphasizes the development of renewable energy sources to combat climate change. However, as photovoltaic expansion accelerates, so does the potential for increased waste, necessitating effective material recycling strategies. Indium, a scarce and valuable element crucial to the production of [...] Read more.

The European Green Deal emphasizes the development of renewable energy sources to combat climate change. However, as photovoltaic expansion accelerates, so does the potential for increased waste, necessitating effective material recycling strategies. Indium, a scarce and valuable element crucial to the production of photovoltaic panels, underscores the necessity for efficient recycling practices to reduce reliance on virgin resources. In a recent laboratory analysis, a CIGS photovoltaic panel underwent a series of processes including crushing, grinding, and homogenization. The concentration of indium, vital for recycling, was meticulously analyzed using ICP-MS and validated through microscopic and composition analyses. Subsequent extraction utilizing 3 M HCl and H₂O₂, followed by electrolysis, yielded a remarkable up to 52% indium recovery within a 48-h timeframe. Importantly, the study encompassed both averaged panel samples and samples from the absorbing layer, emphasizing the comprehensive approach required for efficient recycling. This underscores the critical importance of optimizing recycling processes to mitigate the environmental impact associated with the disposal of photovoltaic panels. By maximizing indium recovery, not only are environmental impacts reduced, but the long-term sustainability of renewable energy technologies is also ensured. This highlights the interconnectedness of recycling practices with the broader goals of achieving a circular economy and securing the viability of renewable energy systems in the fight against climate change. Full article

(This article belongs to the Special Issue Emerging Technologies in the Hydrometallurgical Recycling of Critical Metals)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Recycling, Volume 10, Issue 3 (June 2025) – 37 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI