Circular Economy in Interdisciplinary Perspective: Valorization of Raw Materials, Sustainable Products, and Pro-Ecological Industrial Developments

Topic Information

Dear Colleagues,

The Circular Economy (CE) system is the opposite of the dominant linear economy model, which is based on the principles of "take from the environment, produce, consume and throw away". Due to limited raw material resources and the frequently increasing difficulty in procuring them, the linear economy model is gradually being replaced by a circular economy model assuming the reuse of products (waste) through their recovery and recycling. Product design (eco-design) plays an important role in ensuring the least possible impact is had on the natural environment during products’ life cycles and after their use. CE models described in the literature also include stages of raw material acquisition, effective chemical, biological and material recycling (including intra-production recycling), activities to extend the life of products and possibly repair them, as well as more effective production methods for products using recycled materials. A modern circular economy requires interdisciplinary cooperation between industry and science in order to develop new environmentally friendly materials and practical technological solutions that meet current requirements, e.g., energy efficiency goals. It is worth pointing out that the concept of cleaner production contributes to the development of CE, and it is supported by the results of modeling and experimental verifications performed in academia and non-academic research centers. The determined structure–property relationships help considerably in designing advanced materials and technologies complying with the CE rules.

In this context, this Topic Issue aims to collect research and review papers devoted to up-to-date Circular Economy approaches from an interdisciplinary perspective, including those pertaining to the valorization of raw materials, development of sustainable products, and advancement of pro-ecological industrial solutions. Publications in the broad field of technological development and economic assessments of production, the application and re-use of materials, and products designed with CE in mind are welcome.

Prof. Dr. Krzysztof Pielichowski
Prof. Dr. Piotr Duda
Dr. Michał Łach
Dr. Tomasz Mariusz Majka
Dr. Tomasz Zdeb
Dr. Giovanni De Feo
Topic Editors

Keywords

Participating Journals

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Energies energies	3.2	7.3	2008	16.2 Days	CHF 2600	Submit
Materials materials	3.2	6.4	2008	15.2 Days	CHF 2600	Submit
Recycling recycling	4.6	8.9	2016	20.9 Days	CHF 1800	Submit
Sustainability sustainability	3.3	7.7	2009	19.3 Days	CHF 2400	Submit
Waste waste	-	-	2023	30.5 Days	CHF 1000	Submit

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Published Papers (8 papers)

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All Energies Materials Recycling Sustainability Waste

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24 pages, 3184 KB  

Open AccessArticle

Life Cycle Assessment of Biocomposite Production in Development Stage from Coconut Fiber Utilization

by Viviana Cecilia Soto-Barrera, Fernando Begambre-González, Karol Edith Vellojín-Muñoz, Daniel Fernando Fernandez-Hoyos and Franklin Manuel Torres-Bejarano

Sustainability 2025, 17(18), 8338; https://doi.org/10.3390/su17188338 - 17 Sep 2025

Viewed by 236

Abstract

Agricultural biowaste poses a major environmental challenge when improperly disposed of. An alternative to this is their utilization for producing natural fibers (NFs) to manufacture biocomposites, promoting a circular economy. However, the fact that a product is classified as renewable does not necessarily [...] Read more.

Agricultural biowaste poses a major environmental challenge when improperly disposed of. An alternative to this is their utilization for producing natural fibers (NFs) to manufacture biocomposites, promoting a circular economy. However, the fact that a product is classified as renewable does not necessarily imply that its environmental performance is superior when compared to its conventional market counterpart. For this reason, this study conducted a Life Cycle Assessment (LCA) of biocomposites reinforced with coconut fiber and a polyester resin matrix, using a “cradle-to-gate” approach. Six scenarios were evaluated, grouped into S1 (2–5% fiber) and S2 (20–30% fiber), with and without chemical treatment, plus a reference scenario without fiber utilization. The IPCC 2021 GWP 100 and ReCiPe Midpoint (H) 2016 methods were applied. The results show that the scenarios without chemical treatment (RF-CCT) were environmentally more optimal, reducing CO₂ emissions by up to 7.4% (RF-CCT/H) and 1.70 kg CO₂-eq (RF-CCT/L) compared to conventional practices. The main reasons for these reductions are the avoidance of emissions associated with disposal, decreased reliance on conventional materials, and the omission of chemical treatment, which in turn mitigates critical impacts such as ozone depletion potential (ODP) linked to N₂O emissions from fertilizers (93% contribution) and terrestrial/marine toxicity. Full article

(This article belongs to the Topic Circular Economy in Interdisciplinary Perspective: Valorization of Raw Materials, Sustainable Products, and Pro-Ecological Industrial Developments)

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33 pages, 4786 KB  

Open AccessArticle

The Influence of Lignin Derivatives on the Thermal Properties and Flammability of PLA+PET Blends

by Tomasz M. Majka, Rana Al Nakib, Yusuf Z. Menceloglu and Krzysztof Pielichowski

Materials 2025, 18(17), 4181; https://doi.org/10.3390/ma18174181 - 5 Sep 2025

Viewed by 715

Abstract

This paper presents a detailed analysis of the thermal and flammability properties of polylactide- (PLA) and poly(ethylene terephthalate)- (PET) based polymer blends with biofillers, such as calcium lignosulfonate (CLS), lignosulfonamide (SA) and lignosulfonate modified with tannic acid (BMT) and gallic acid (BMG). Calorimetric [...] Read more.

This paper presents a detailed analysis of the thermal and flammability properties of polylactide- (PLA) and poly(ethylene terephthalate)- (PET) based polymer blends with biofillers, such as calcium lignosulfonate (CLS), lignosulfonamide (SA) and lignosulfonate modified with tannic acid (BMT) and gallic acid (BMG). Calorimetric studies revealed the presence of two glass transitions, one cold crystallization temperature, and two melting points, confirming the partial immiscibility of the PLA and PET phases. The additives had different effects on the temperatures and ranges of phase transformations—BMT restricted PLA chain mobility, while CLS acted as a nucleating agent that promoted crystallization. Thermogravimetric analyses (TGA) analyses showed that the additives significantly affected the thermal stability under oxidizing conditions, some (e.g., BMG) lowered the onset degradation temperature, while the others (BMT, SA) increased the residual char content. The additives also altered combustion behavior; particularly BMG that most effectively reduced flammability, promoted char formation, and extended combustion time. CLS reduced PET flammability more effectively than PLA, especially at higher PET content (e.g., 65% reduction in PET for 2:1/CLS). SA inhibited only PLA combustion, with strong effects at higher PLA content (up to 76% reduction for 2:1/SA). BMT mainly reduced PET flammability (48% reduction in 1:1/BMT), while BMG inhibited PET more strongly at lower PET content (76% reduction for 2:1/BMG). The effect of each additive also depended on the PLA:PET ratio in the blend. FTIR analysis of the char residues revealed functional groups associated with decomposition products of carboxylic acids and aromatic esters. Ultimately, only blends containing BMT and BMG met the requirements for flammability class FV-1, while SA met FV-2 classification. BMG was the most effective additive, offering enhanced thermal stability, ignition delay, and durable char formation, making it a promising bio- based flame retardant for sustainable polyester materials. Full article

(This article belongs to the Topic Circular Economy in Interdisciplinary Perspective: Valorization of Raw Materials, Sustainable Products, and Pro-Ecological Industrial Developments)

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23 pages, 1776 KB  

Open AccessArticle

Assessment of Greenhouse Gas Emissions, Energy Demand and Solid Waste Generation Between Two Manufacturing Processes: A Case Study

by Fernando Nogueira Cardoso, João da Cruz Payão Filho, Margareth Nascimento de Souza Lira and Claudinei de Souza Guimarães

Recycling 2025, 10(4), 163; https://doi.org/10.3390/recycling10040163 - 13 Aug 2025

Viewed by 520

Abstract

Additive manufacturing (AM) is an Industry 4.0 technology that assists or replaces the conventional manufacturing (CM) of complex geometries in various sectors, including transport, steel, aerospace, military, and architecture. The aim is to improve processes, reduce energy consumption, atmospheric emissions, and solid waste, [...] Read more.

Additive manufacturing (AM) is an Industry 4.0 technology that assists or replaces the conventional manufacturing (CM) of complex geometries in various sectors, including transport, steel, aerospace, military, and architecture. The aim is to improve processes, reduce energy consumption, atmospheric emissions, and solid waste, and streamline stages while complying with the new environmental regulations. The main objective of this work was to carry out a cradle-to-gate Life Cycle Assessment (LCA), considering the raw material extraction, pre-processing, manufacturing, and post-processing stages, comparing two manufacturing methods for the same ER-90 metal flange part, conventional forging and wire and arc additive manufacturing (WAAM), all following the requirements and operations proposed by the ISO 14040/44 standard. WAAM is a Directed Energy Deposition (DED) technology that uses welding techniques to produce 3D objects with more complex geometries. Compared to the forging industry, which requires a lot of heat and kinetic energy in its metal part production stages, WAAM is a more sustainable and modern alternative because it does not require high temperatures and energy to produce the same parts. The environmental indicators compared in the process stages were energy consumption, greenhouse gas (GHG) emissions, and solid waste. The total energy consumption in AM was 18,846.61 MJ, the GHG emissions were 864.49 kgCO₂-eq, and the solid waste generated was 142.34 kg, which were 63.8 %, 90.5%, and 31.6% lower than the environmental indicators calculated for CM, respectively. Full article

(This article belongs to the Topic Circular Economy in Interdisciplinary Perspective: Valorization of Raw Materials, Sustainable Products, and Pro-Ecological Industrial Developments)

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27 pages, 355 KB  

Open AccessReview

Comprehensive Review of Life Cycle Carbon Footprint in Edible Vegetable Oils: Current Status, Impact Factors, and Mitigation Strategies

by Shuang Zhao, Sheng Yang, Qi Huang, Haochen Zhu, Junqing Xu, Dan Fu and Guangming Li

Waste 2025, 3(3), 26; https://doi.org/10.3390/waste3030026 - 6 Aug 2025

Viewed by 1038

Abstract

Amidst global climate change, carbon emissions across the edible vegetable oil supply chain are critical for sustainable development. This paper systematically reviews the existing literature, employing life cycle assessment (LCA) to analyze key factors influencing carbon footprints at stages including cultivation, processing, and [...] Read more.

Amidst global climate change, carbon emissions across the edible vegetable oil supply chain are critical for sustainable development. This paper systematically reviews the existing literature, employing life cycle assessment (LCA) to analyze key factors influencing carbon footprints at stages including cultivation, processing, and transportation. It reveals the differential impacts of fertilizer application, energy structures, and regional policies. Unlike previous reviews that focus on single crops or regions, this study uniquely integrates global data across major edible oils, identifying three critical gaps: methodological inconsistency (60% of studies deviate from the requirements and guidelines for LCA); data imbalance (80% concentrated on soybean/rapeseed); weak policy-technical linkage. Key findings: fertilizer emissions dominate cultivation (40–60% of total footprint), while renewable energy substitution in processing reduces emissions by 35%. Future efforts should prioritize multidisciplinary integration, enhanced data infrastructure, and policy scenario analysis to provide scientific insights for the low-carbon transformation of the global edible oil industry. Full article

(This article belongs to the Topic Circular Economy in Interdisciplinary Perspective: Valorization of Raw Materials, Sustainable Products, and Pro-Ecological Industrial Developments)

20 pages, 2299 KB  

Open AccessArticle

Valorization of Waste Mineral Wool and Low-Rank Peat in the Fertilizer Industry in the Context of a Resource-Efficient Circular Economy

by Marta Huculak-Mączka, Dominik Nieweś, Kinga Marecka and Magdalena Braun-Giwerska

Sustainability 2025, 17(15), 7083; https://doi.org/10.3390/su17157083 - 5 Aug 2025

Viewed by 460

Abstract

This study aims to evaluate eco-innovative solutions in the fertilizer industry that allow for waste valorization in the context of a resource-efficient circular economy. A comprehensive reuse strategy was developed for low-rank peat and post-cultivation horticultural mineral wool, involving the extraction of valuable [...] Read more.

This study aims to evaluate eco-innovative solutions in the fertilizer industry that allow for waste valorization in the context of a resource-efficient circular economy. A comprehensive reuse strategy was developed for low-rank peat and post-cultivation horticultural mineral wool, involving the extraction of valuable humic substances from peat and residual nutrients from used mineral wool, followed by the use of both post-extraction residues to produce organic–mineral substrates. The resulting products/semifinished products were characterized in terms of their composition and properties, which met the requirements necessary to obtain the admission of this type of product to the market in accordance with the Regulation of the Minister for Agriculture and Rural Development of 18 June 2008 on the implementation of certain provisions of the Act on fertilizers and fertilization (Journal of Laws No 119, item 765). Elemental analysis, FTIR spectroscopy, and solid-state CP-MAS ¹³C NMR spectroscopy suggest that post-extraction peat has a relatively condensed structure with a high C content (47.4%) and a reduced O/C atomic ratio and is rich in alkyl-like matter (63.2%) but devoid of some functional groups in favor of extracted fulvic acids. Therefore, it remains a valuable organic biowaste, which, in combination with post-extraction waste mineral wool in a ratio of 60:40 and possibly the addition of mineral nutrients, allows us to obtain a completely new substrate with a bulk density of 264 g/m³, a salinity of 7.8 g/dm³ and a pH of 5.3, with an appropriate content of heavy metals and with no impurities, meeting the requirements of this type of product. A liquid fertilizer based on an extract containing previously recovered nutrients also meets the criteria in terms of quality and content of impurities and can potentially be used as a fertilizing product suitable for agricultural crops. This study demonstrates a feasible pathway for transforming specific waste streams into valuable agricultural inputs, contributing to environmental protection and sustainable production. The production of a new liquid fertilizer using nutrients recovered from post-cultivation mineral wool and the preparation of an organic–mineral substrate using post-extraction solid residue is a rational strategy for recycling hard-to-biodegrade end-of-life products. Full article

(This article belongs to the Topic Circular Economy in Interdisciplinary Perspective: Valorization of Raw Materials, Sustainable Products, and Pro-Ecological Industrial Developments)

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19 pages, 17315 KB  

Open AccessArticle

Development and Mechanical Characterization of Environmentally Friendly PLA/Crop Waste Green Composites

by Karolina Ewelina Mazur, Tomasz Wacław Witko, Alicja Kośmider and Stanisław Tadeusz Kuciel

Materials 2025, 18(15), 3608; https://doi.org/10.3390/ma18153608 - 31 Jul 2025

Viewed by 485

Abstract

This study presents the fabrication and characterization of sustainable polylactic acid (PLA)-based biocomposites reinforced with bio-origin fillers derived from food waste: seashells, eggshells, walnut shells, and spent coffee grounds. All fillers were introduced at 15 wt% into a commercial PLA matrix modified with [...] Read more.

This study presents the fabrication and characterization of sustainable polylactic acid (PLA)-based biocomposites reinforced with bio-origin fillers derived from food waste: seashells, eggshells, walnut shells, and spent coffee grounds. All fillers were introduced at 15 wt% into a commercial PLA matrix modified with a compatibilizer to improve interfacial adhesion. Mechanical properties (tensile, flexural, and impact strength), morphological characteristics (via SEM), and hydrolytic aging behavior were evaluated. Among the tested systems, PLA reinforced with seashells (PLA15S) and coffee grounds (PLA15C) demonstrated the most balanced mechanical performance, with PLA15S achieving a tensile strength increase of 72% compared to neat PLA. Notably, PLA15C exhibited the highest stability after 28 days of hydrothermal aging, retaining ~36% of its initial tensile strength, outperforming other systems. In contrast, walnut-shell-filled composites showed the most severe degradation, losing over 98% of their mechanical strength after aging. The results indicate that both the physicochemical nature and morphology of the biofiller play critical roles in determining mechanical reinforcement and degradation resistance. This research underlines the feasibility of valorizing agri-food residues into biodegradable, semi-structural PLA composites for potential use in sustainable packaging or non-load-bearing structural applications. Full article

(This article belongs to the Topic Circular Economy in Interdisciplinary Perspective: Valorization of Raw Materials, Sustainable Products, and Pro-Ecological Industrial Developments)

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16 pages, 2185 KB  

Open AccessArticle

Maximizing Energy Recovery from Waste Tires Through Cement Production Optimization in Togo—A Case Study

by Mona-Maria Narra, Essossinam Beguedou, Satyanarayana Narra and Michael Nelles

Waste 2025, 3(2), 19; https://doi.org/10.3390/waste3020019 - 8 Jun 2025

Viewed by 1264

Abstract

The cement industry faces increasing energy costs and environmental pressures, driving the adoption of alternative fuels derived from waste materials. In Togo, approximately 350,000 t of end-of-life tires (ELT) are generated annually, creating significant environmental and health hazards through uncontrolled disposal and burning [...] Read more.

The cement industry faces increasing energy costs and environmental pressures, driving the adoption of alternative fuels derived from waste materials. In Togo, approximately 350,000 t of end-of-life tires (ELT) are generated annually, creating significant environmental and health hazards through uncontrolled disposal and burning practices. This study investigated the technical feasibility and economic viability of incorporating waste tires as an alternative fuel in cement manufacturing. Tire-derived fuel (TDF) performance was evaluated by comparing pre-processed industrial tires with unprocessed ones, focusing on clinker production loss, elemental composition, heating values, and bulk density. The results demonstrate that TDF exhibits superior performance characteristics, with the highest heating values, and meets all the required specifications for cement production. In contrast, whole tire incineration fails to satisfy the recommended criteria, necessitating blending with conventional fuels to maintain clinker quality and combustion efficiency. The investigation revealed no significant adverse effects on production processes or clinker quality while achieving substantial reductions in nitrogen and sulfur oxide emissions. The experimental results were compared with the theoretical burnout times to optimize the shredding operations and injection methods. However, several challenges remain unaddressed, including the absence of streamlined handling processes, limited understanding of long-term ecological and health impacts, and insufficient techno-economic assessments. Future research should prioritize identifying critical aging points, investigating self-rejuvenating behaviors, and quantifying long-term environmental implications. These findings provide a foundation for developing computational models to optimize the mixing ratios of alternative and fossil fuels in cement manufacturing, offering significant environmental, economic, and societal benefits for the cement industry. Full article

(This article belongs to the Topic Circular Economy in Interdisciplinary Perspective: Valorization of Raw Materials, Sustainable Products, and Pro-Ecological Industrial Developments)

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25 pages, 5651 KB  

Open AccessArticle

Kinetic and Thermodynamic Analysis of Fried Tilapia Fish Waste Pyrolysis for Biofuel Production

by Mohamed Koraiem M. Handawy, Ik-Tae Im, Gyo Woo Lee and Hamada Mohamed Abdelmotalib

Recycling 2025, 10(2), 61; https://doi.org/10.3390/recycling10020061 - 1 Apr 2025

Viewed by 984

Abstract

Converting food waste into biofuel resources is considered a promising approach to address the rapid increase in energy demand, reduce dependence on fossil fuels, and decrease environmental hazards. In Egypt, large quantities of fried tilapia fish waste are produced in restaurants and households, [...] Read more.

Converting food waste into biofuel resources is considered a promising approach to address the rapid increase in energy demand, reduce dependence on fossil fuels, and decrease environmental hazards. In Egypt, large quantities of fried tilapia fish waste are produced in restaurants and households, posing challenges for proper waste management due to its decaying nature. The current study investigates the kinetic triplet and thermodynamic parameters of fried tilapia fish waste (FTFW) pyrolysis. Kinetic analysis was carried out using four iso-conversional models, Friedman, Kissinger–Akahira–Sunose (KAS), Flynn–Wall–Ozawa (FWO), and Starink, at heating rates of 10, 15, and 20 °C/min. The study findings indicate that FTFW decomposes within the temperature range of 382–407 °C. The estimated activation energy using the Friedman, FWO, KAS, and Starink methods ranged from 43.2 to 208.2, 31.3 to 148.3, 22.3 to 179.3, and 24.1 to 181.3 kJ/mol, respectively, with average values of 118.4, 96.7, 109.7, and 100.5 kJ/mol, respectively. The average enthalpy change determined using the Friedman, FWO, KAS, and Starink methods was 113.45, 91.78, 95.58, and 104.73 kJ/mol, respectively. The average values of Gibbs free energy change for the Friedman, KAS, FWO, and Starink, methods were 192.71, 171.04, 174.83, and 183.99 kJ/mol, respectively. Full article

(This article belongs to the Topic Circular Economy in Interdisciplinary Perspective: Valorization of Raw Materials, Sustainable Products, and Pro-Ecological Industrial Developments)

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