Submit to Recycling Review for Recycling

Journal Menu

Journal Browser

► Journal Browser

Recycling, Volume 10, Issue 3 (June 2025) – 6 articles

Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
You may sign up for e-mail alerts to receive table of contents of newly released issues.
PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Reader to open them.

Order results

Result details

Show export options Show export options

Select all

Export citation of selected articles as:

23 pages, 3745 KiB

Open AccessArticle

Towards Circularity in Anaerobic Digestion: Methane Yield Enhancement Using Biochar from Co-Pyrolysis of Anaerobic Sludge and Residual Lignocellulosic Biomass

by César Omar Díaz Lara, Diana Cabañas Vargas, Julio César Sacramento Rivero, Sergio Baz-Rodríguez, Juan Enrique Ruiz Espinoza, Erick Alberto Aguilera-Cauich, José Martín Baas-López and Daniella E. Pacheco-Catalán

Recycling 2025, 10(3), 84; https://doi.org/10.3390/recycling10030084 (registering DOI) - 1 May 2025

Abstract

Improper management of anaerobic pig sludge poses significant environmental and health risks. Converting this waste into biochar to enhance methane production during anaerobic digestion (AD) presents an environmentally sound and circular solution, especially when the biochar is produced through co-pyrolysis with lignocellulosic biomass residues. This study first determined the co-pyrolysis biomass ratio (anaerobic sludge to lignocellulosic biomass) that caused the highest increase on methane yield. Subsequently, the effects of biochar dosage (6, 12, 18, 24, and 30 g/L) and particle size (0.5–1 cm, 212–355 µm, and <53 µm) on methane production were assessed. Biochar derived from up to 25 % anaerobic pig sludge increased methane yield by 74.49 ± 1.25 % without compromising its catalytic effect. Methane yield was significantly affected by both biochar dosage and particle size, with best results observed at dosages of 12–18 g/L. These findings highlight the feasibility of the co-pyrolysis of anaerobic pig sludge and lignocellulosic residues as an attractive circular solution for integrated waste management and energy production. Full article

► Show Figures

Figure 1

13 pages, 2797 KiB

Open AccessArticle

Forecasting the Shredder Output Volume Flow Towards Dynamic Control in Waste Management

by Tatjana Lasch, Jason Imhof, Lisa Kandlbauer, Renato Sarc and Karim Khodier

Recycling 2025, 10(3), 83; https://doi.org/10.3390/recycling10030083 (registering DOI) - 1 May 2025

Abstract

The digitalization of mechanical waste treatment can have a supporting effect in recovering valuable raw materials from mixed solid waste, achieving the EU’s recycling targets, and developing the waste industry into a circular economy. Therefore, influencing factors on machines and the entire plant must be known. Furthermore, optimization potentials can be developed with the help of digital approaches, such as dynamic control of machine and plant operation, to be able to control the heterogeneous material streams to enable optimized treatment and preserve valuable materials. To establish dynamic control in waste treatment machines, sensors are required to record the necessary variable parameters. In this work, the focus of those variables is placed on the volume flow leaving the shredding machine, where a volume flow sensor is used as a sensor system. To predict the volume flow of the shredder’s output to create a possible dynamic control, forecasting with ARIMA models is used. Initial results show that it is possible to predict a heterogeneous material stream with a selected model, currently over a time period of 10 s. However, the testing of additional prediction models still offers the opportunity of predicting the material stream over a longer period of time to enable dynamic control. Full article

► Show Figures

Figure 1

16 pages, 4956 KiB

Open AccessArticle

New Strategy for Upcycling Marine Plastic Waste Through the Development of a Diamine-Functionalized Poly(ethylene terephthalate) Compatibilizer

by Pedro V. Rodrigues, Sibele P. Cestari, Vasco Cruz, M. Cidália R. Castro and Ana Vera Machado

Recycling 2025, 10(3), 82; https://doi.org/10.3390/recycling10030082 (registering DOI) - 1 May 2025

Abstract

A compatibilizer for low-density polyethylene (LDPE)/poly(ethylene terephthalate) (PET) blends was developed. This compatibilizer consists of amine-functionalized PET, which is blended with maleated polyethylene to form a copolymer. The goal is to use this compatibilizer in the future for recycling plastic waste from the marine environment. Fourier-transform infrared spectroscopy confirmed the successful incorporation of amine groups into PET chains through the addition of p-phenylenediamine in a molten state. An increase in diamine content allowed for the visualization of three bands where PET reacted with the diamine. Differential scanning calorimetry suggested that the polyester chains were grafted onto the maleated polyethylene backbone, with crystallinity increasing up to 2.5% diamine content. Scanning electron microscopy (SEM) images showed that the LDPE/PET blend resulted in a continuous polyethylene matrix with a dispersed polyester phase. The blend compatibilized with modified maleated polyethylene, and functionalized PET exhibited an improved interface. Oscillatory rheology and dynamic mechanical analysis indicated that the developed compatibilizer positively impacted the mechanical properties of the compatibilized LDPE/PET blends. This new approach enables the creation of innovative strategies for enhancing the properties of pre-existing polyolefin/polyester recycled blends. Full article

► Show Figures

Figure 1

14 pages, 9369 KiB

Open AccessArticle

Synergetic Treatment of BOF Slag and Copper Slag via Oxidation–Magnetic Separation for MgFe₂O₄ Preparation and Non-Magnetic Slag Stabilization

by Bowen Cao, Nan Wang and Min Chen

Recycling 2025, 10(3), 81; https://doi.org/10.3390/recycling10030081 (registering DOI) - 1 May 2025

Abstract

This study proposes a synergistic treatment method for BOF slag and copper slag via oxidation–magnetic separation, with the dual goals of preparing MgFe₂O₄ magnetic material and stabilizing the non-magnetic slag. The effects of copper slag addition, the oxidation temperature and the oxidation time on the phase transformation and MgFe₂O₄ morphology during the oxidation process are investigated. The results show that copper slag addition can release the simple iron oxides of FeO and Fe₂O₃ from iron-containing phases from BOF slag and copper slag, promoting the synthesis of MgFe₂O₄. Furthermore, the oxidation temperature and oxidation time have a significant influence on the size of the MgFe₂O₄ particles. To obtain the MgFe₂O₄ magnetic material, the optimum oxidation parameters were used, with an oxidation degree of Fe²⁺ of 95.85% and a yield of MgFe₂O₄ of 90.31%. In addition, the main phase of non-magnetic slag was Ca₂SiO₄, and both free CaO and free MgO from BOF slag were eliminated, indicating a potential application in construction materials. This technology maximizes resource utilization and the valorization of metallurgical solid waste. Full article

► Show Figures

Graphical abstract

17 pages, 5835 KiB

Open AccessArticle

Effect of Solvent Pre-Treatment on the Leaching of Copper During Printed Circuit Board Recycling

by Ahmed Tarek Ismail Mohamed, Giuliana Schimperna, Gianluca Cantoni, Francesca Demichelis, Debora Fino, Sara Perucchini, Francesca Rubertelli and Francesco Laviano

Recycling 2025, 10(3), 80; https://doi.org/10.3390/recycling10030080 (registering DOI) - 1 May 2025

Abstract

Printed circuit boards (PCBs) are fundamental components of electronic devices, acting as an important source of various valuable metals such as copper, gold, and silver. Efficient recycling methods that offer high recovery rates are essential to the full reutilization of these materials. Hydrometallurgical leaching is a prominent technique for metal recovery, but its efficiency can be significantly enhanced through solvent pre-treatment. In this study, an experimental analysis of the material composition of different categories of PCBs is presented. In addition, the study evaluates the influence of particle size on the subsequent copper leaching process and the efficiency of copper recovery. These investigations aim to better understand the material composition of PCBs and propose an optimized material recovery technique. The study finds that there are significant variances among the different categories of PCBs investigated, allowing a more informed handling process of WEEE. This research suggests that solvent pretreatment using DMSO for PCB particle sizes between 5.6 mm and 2 mm would be a good optimization technique, mitigating the drawbacks of treating fine particles while maintaining appealing recovery efficiency. Full article

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

► Show Figures

Figure 1

16 pages, 11739 KiB

Open AccessArticle

Use of Secondary Cellulose Fibers as a Replacement for the Basic Components of Core Insulators of Vacuum Insulation Panels

by Jiří Zach, Jitka Peterková, Vítězslav Novák, Mitja Košir and David Božiček

Recycling 2025, 10(3), 79; https://doi.org/10.3390/recycling10030079 (registering DOI) - 1 May 2025

Abstract

The ever-increasing requirements in the field of energy efficiency of buildings imply the necessity of using an ever-increasing amount of insulation in building structures. However, together with the requirements of the new EPBD directive EU/2024/1275, it is also necessary to monitor the carbon footprint of individual materials incorporated into the building structure. The aim of the research work is to substitute primary raw materials used for the production of vacuum insulation panels (VIPs) with secondary cellulose fibers produced by recycling newsprint. Five recipes were proposed to verify the substitution effect for individual key raw materials of core insulation for VIPs. Key (primarily thermal insulation) properties were determined on laboratory-produced samples, and it was found that the proposed hybrid core insulations with secondary cellulose fibers from recycled newsprint exhibit very favorable properties and could be used for the production of VIPs used in building structures. Full article

► Show Figures

Figure 1

Show export options Show export options

Select all

Export citation of selected articles as:

Displaying articles 1-6

Previous Issue

Volume 10, April

Journal Menu

Journal Browser

Recycling, Volume 10, Issue 3 (June 2025) – 6 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI