Recycling

66 pages, 8543 KiB

Open AccessReview

Perspectives on Plastic Waste Management: Challenges and Possible Solutions to Ensure Its Sustainable Use

by Afonso D. Macheca, Bridget Mutuma, José L. Adalima, Emmanuel Midheme, Luís H. M. Lúcas, Valentine K. Ochanda and Sabelo Dalton Mhlanga

Recycling 2024, 9(5), 77; https://doi.org/10.3390/recycling9050077 (registering DOI) - 13 Sep 2024

Abstract

The pollution of the environment by plastics is a global problem that is real and needs to be resolved urgently. The authors argue that banning the use of plastic is not a reasonable and rational solution for the problem because plastics have many [...] Read more.

The pollution of the environment by plastics is a global problem that is real and needs to be resolved urgently. The authors argue that banning the use of plastic is not a reasonable and rational solution for the problem because plastics have many useful applications. Solutions to the problem must involve developing scientific approaches as well as global efforts and strategies. The world’s approach needs to be guided by an economic model that eliminates or minimizes the amount of plastics in the waste stream. As long as most plastic materials are not made from a single polymer, then the idea of “recycling 100% of plastics” is so far an unrealistic solution. The development of biodegradable plastics is still far from being an effective solution because besides being expensive and having limitations in engineering applications when compared to petroleum-based ones, biodegradable plastics still require specific conditions for their biodegradation. Comprehensive studies on microplastic particles are needed, focusing mainly on the source of the particles, their distribution, transport, fate in different environments, and toxicological effects and mechanisms. Since plastic pollution is a global problem, its minimization will require an increased international cooperation platform and partnerships at a global level. While current technologies and strategies are not solving the environmental problem caused by waste plastic, the most effective solution would be to adopt the first two levels of the waste management hierarchy, which are “reduce” and “reuse”. Full article

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26 pages, 3662 KiB

Open AccessReview

Pathways to Circular Economy for Electric Vehicle Batteries

by Subin Antony Jose, Lyndsey Dworkin, Saihan Montano, William Charles Noack, Nick Rusche, Daniel Williams and Pradeep L. Menezes

Recycling 2024, 9(5), 76; https://doi.org/10.3390/recycling9050076 - 11 Sep 2024

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Abstract

The global shift towards sustainability is driving the electrification of transportation and the adoption of clean energy storage solutions, moving away from internal combustion engines. This transition significantly impacts lithium-ion battery production in the electric vehicle (EV) market. This paper summarizes specialized topics [...] Read more.

The global shift towards sustainability is driving the electrification of transportation and the adoption of clean energy storage solutions, moving away from internal combustion engines. This transition significantly impacts lithium-ion battery production in the electric vehicle (EV) market. This paper summarizes specialized topics to highlight regional differences and specific challenges related to electric batteries, focusing on how pollution from gas consumption, distribution, usage, and lithium production affects society. EV batteries offer promising opportunities for a sustainable future, considering their economic and environmental impacts and the importance of understanding their lifecycle. This analysis delves into the recovery of materials and various methods for extracting lithium and manufacturing EV batteries. Efficient lithium recovery is crucial and globally significant, with liquid extraction presenting a more environmentally friendly option. By addressing these challenges, this paper provides an overview of the rationale behind supporting the future of EVs. Full article

(This article belongs to the Special Issue Lithium-Ion and Next-Generation Batteries Recycling)

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18 pages, 8316 KiB

Open AccessArticle

A Comparative Analysis of Target Scenarios for Municipal Waste Reduction in Croatia’s Leading Tourist Towns

by Ivana Smoljko and Jelena Sedlar

Recycling 2024, 9(5), 75; https://doi.org/10.3390/recycling9050075 - 5 Sep 2024

Viewed by 371

Abstract

In this study, we examined the correlation between the collected municipal waste (MW) and the tourism intensity (TI) in five of Croatia’s most popular tourist towns—Zagreb, Poreč, Rovinj, Split, and Dubrovnik—from 2015 to 2021. Furthermore, we conducted a comparative analysis of target scenarios [...] Read more.

In this study, we examined the correlation between the collected municipal waste (MW) and the tourism intensity (TI) in five of Croatia’s most popular tourist towns—Zagreb, Poreč, Rovinj, Split, and Dubrovnik—from 2015 to 2021. Furthermore, we conducted a comparative analysis of target scenarios for municipal waste reduction in these tourist towns based on population changes and the amount of separately collected and residual MW collected to achieve EU targets for processing MW for reuse and recycling. The TI indicator quantifies the population’s theoretical multiplication during tourist influx, providing a clear picture of the pressure exerted by tourism. Rovinj and Poreč have the highest TIs, while larger cities like Dubrovnik, Split, and Zagreb have lower average TI values. The correlation between the collected MW and the tourism intensity in Dubrovnik is very high and positive, in Zagreb and Rovinj it is high and negative, while Split has a higher positive correlation than Poreč. The results for the MW preparation rates for reuse and recycling from 2015 to 2021 and future projections for 2021–2035 suggest that, in five of Croatia’s leading tourist towns, the imperative must be to decrease residual MW, promote separation at the source, and separate MW collection to meet EU targets. Given the challenges of meeting all three—or even two or one—of the EU’s targets of 50% by 2025, 60% by 2030, and 65% by 2035, the current waste separation system must be improved. This study contributes to the scientific community by addressing the gap in the current knowledge on the effects of population changes caused by tourism on MW in tourist destinations. The findings could be relevant for practitioners and policymakers planning MW collection, processing, and recovery in tourism-oriented economies, particularly in Croatia’s top tourist destinations. Full article

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21 pages, 5090 KiB

Open AccessArticle

Adsorptive Removal of Phosphate from Water Using Aluminum Terephthalate (MIL-53) Metal–Organic Framework and Its Hollow Fiber Module

by Shein-Fu Wu and Hsin-Ming Cheng

Recycling 2024, 9(5), 74; https://doi.org/10.3390/recycling9050074 - 5 Sep 2024

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Abstract

The aluminum terephthalate (MIL-53) metal–organic framework (MOF) (MIL-53(Al)) was evaluated as an adsorbent for removing phosphates from aqueous solutions. XRD and FTIR were used to confirm the molecular structure. TGA/DSC was used to measure its stability. The green synthesizing MIL-53(Al) showed good performance [...] Read more.

The aluminum terephthalate (MIL-53) metal–organic framework (MOF) (MIL-53(Al)) was evaluated as an adsorbent for removing phosphates from aqueous solutions. XRD and FTIR were used to confirm the molecular structure. TGA/DSC was used to measure its stability. The green synthesizing MIL-53(Al) showed good performance as a highly efficient adsorbent. The adsorbed MIL-53(Al) nanoparticles still retain their original morphology according to SEM, allowing it to be easily separated from the aqueous solution via filtration. Additionally, the thermal stability of synthesized MIL-53(Al) is capable of withstanding temperatures up to 500 °C, as confirmed by TGA/DSC. Using different initial concentrations of Na₂HPO₄ and ICP-OES measurements, we determined the adsorption values of Na₂HPO₄ by MIL-53(Al) as a function of time. Three kinetic models (pseudo-first-order, pseudo-second-order, and Elovich) and three isotherm models (Langmuir, Freundlich, and Temkin) were used to evaluate the phosphate adsorption behavior of MIL-53(Al) powder in Na₂HPO₄ aqueous solution. Error functions are used to evaluate various kinetic and isotherm models related to different physical processes. From the analysis of the adsorption experiments, the Elovich model is the best-fitting kinetic model, showing that the adsorption rate decreases with increasing adsorption capacity. Furthermore, error function analysis identified the Freundlich model as the most suitable, indicating that complicated adsorption coexists with physisorption, and chemisorption synergistically drives the adsorption process. The module utilizing MIL-53(Al) hollow fibers also demonstrated preliminary attempts at phosphate adsorption and desorption for the first time. This work demonstrated that MIL-53(Al) is an exceptionally stable adsorbent for removing phosphate from contaminated wastewater. Full article

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28 pages, 11926 KiB

Open AccessArticle

Performance Assessment of One-Part Self-Compacted Geopolymer Concrete Containing Recycled Concrete Aggregate: A Critical Comparison Using Artificial Neural Network (ANN) and Linear Regression Models

by Bahareh Nikmehr, Bidur Kafle and Riyadh Al-Ameri

Recycling 2024, 9(5), 73; https://doi.org/10.3390/recycling9050073 - 31 Aug 2024

Viewed by 540

Abstract

Geopolymer concrete, a cement-free concrete with recycled concrete aggregate (RCA), offers an eco-friendly solution for reducing carbon emissions from cement production and reusing a significant amount of old concrete from construction and demolition waste. This research on self-compacted, ambient-cured, and low-carbon concrete demonstrates [...] Read more.

Geopolymer concrete, a cement-free concrete with recycled concrete aggregate (RCA), offers an eco-friendly solution for reducing carbon emissions from cement production and reusing a significant amount of old concrete from construction and demolition waste. This research on self-compacted, ambient-cured, and low-carbon concrete demonstrates the superior performance of one-part geopolymer concrete made from recycled materials. It is achieved by optimally replacing treated RCA with a unique method that involves coating the recycled aggregates with a one-part geopolymer slurry composed of fly ash, micro fly ash, slag, and anhydrous sodium metasilicate. The research presented in this paper introduces predictive models to assist researchers in optimising concrete mix designs based on RCA rates and treatment methods, including the incorporation of coated recycled concrete aggregates and basalt fibres. This study addresses the knowledge gap regarding geopolymer concrete based on recycled aggregate, various RCA rates, and novel RCA treatments. The novelty of the paper also lies in presenting the effectiveness of Artificial Neural Network (ANN) models in accurately predicting the compressive strength, splitting tensile strength, and modulus of elasticity for self-compacting geopolymer concrete with various rates of RCA replacement. This addresses a knowledge gap in existing research on ANN models for the prediction of geopolymer concrete properties based on RCA rate and treatment. The ANN models developed in this research predict results that are more comparable to experimental outcomes, showcasing superior accuracy compared to linear regression models. Full article

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17 pages, 3525 KiB

Open AccessArticle

Circularity: Understanding the Environmental Tradeoffs of Additive Manufacturing with Waste Plastics

by Eesha Bilal, Yael R. Glazer, Doug M. Sassaman, Carolyn C. Seepersad and Michael E. Webber

Recycling 2024, 9(5), 72; https://doi.org/10.3390/recycling9050072 - 28 Aug 2024

Viewed by 543

Abstract

This paper examines the emissions tradeoffs of additive manufacturing (i.e., 3D printing) using plastic waste in fused granular fabrication (FGF) versus traditional fused filament fabrication (FFF) and injection molding (IM). A ‘cradle-to-gate’ life cycle assessment (LCA) was utilized to compare these methods, built [...] Read more.

This paper examines the emissions tradeoffs of additive manufacturing (i.e., 3D printing) using plastic waste in fused granular fabrication (FGF) versus traditional fused filament fabrication (FFF) and injection molding (IM). A ‘cradle-to-gate’ life cycle assessment (LCA) was utilized to compare these methods, built in OpenLCA v1.11.0 with the Ecoinvent v3.9.1 database. Different scenarios were used to evaluate the impacts of varying transportation and material inputs, highlighting critical emission contributors in manufacturing plastic goods. FGF with waste plastic can significantly reduce climate impact by 82.1% relative to FFF and 70.6% relative to IM for a specified unit product. Even with varied transportation and materials, FGF is a lower CO₂-equivalent emitting method. Utilizing FGF with waste plastic as a manufacturing method could reduce emissions and divert plastic from landfills and the environment, thereby contributing to a circular plastic economy. Full article

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20 pages, 717 KiB

Open AccessArticle

Barriers, Challenges, and Opportunities in the Adoption of the Circular Economy in Mexico: An Analysis through Social Perception

by Alejandro Padilla-Rivera, Magdalena Morales Brizard, Nicolas Merveille and Leonor Patricia Güereca-Hernandez

Recycling 2024, 9(5), 71; https://doi.org/10.3390/recycling9050071 - 27 Aug 2024

Viewed by 435

Abstract

This study explores the transition toward sustainable economic models through the circular economy (CE) in Mexico. Utilizing a mixed-methods approach, this research incorporates a comprehensive literature review and analyzes responses from 42 stakeholders, gathered through surveys and focus groups. These stakeholders comprise a [...] Read more.

This study explores the transition toward sustainable economic models through the circular economy (CE) in Mexico. Utilizing a mixed-methods approach, this research incorporates a comprehensive literature review and analyzes responses from 42 stakeholders, gathered through surveys and focus groups. These stakeholders comprise a diverse group including PhD students, professors, researchers, industry professionals in sustainability and the environment, and government advisors and coordinators from the Mexican Secretary of Environment. This representative sample provides a broad perspective on the barriers, opportunities, and societal perceptions regarding CE. The findings reveal significant challenges such as economic barriers, regulatory inadequacies, and a lack of awareness and education, all of which hinder the adoption of CE practices. Despite these challenges, there is a generally optimistic view among stakeholders about CE’s potential to positively impact societal needs, suggesting robust opportunities for innovation and policy enhancement to foster sustainable development. Key recommendations include intensifying educational programs to elevate public understanding and engagement, formulating supportive policies that facilitate CE adoption, and promoting intersectoral collaboration to leverage collective expertise and resources. Additionally, the research underscores the necessity of integrating CE principles into urban planning and policy frameworks to effectively address specific local challenges such as waste management, pollution, and urban sprawl. By providing a detailed analysis of the current state and potential of CE in Mexico, this paper contributes valuable insights to the global discourse on sustainability. It proposes strategic actions to overcome existing hurdles and capitalize on opportunities within the CE framework, charting a path forward for Mexico and serving as a model for other regions facing similar sustainability challenges Full article

(This article belongs to the Special Issue Sustainability of the Circular Economy)

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Recycling, Volume 9, Issue 5 (October 2024) – 7 articles

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