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Recycling
Volume 7
Issue 1
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Recycling, Volume 7, Issue 1 (February 2022) – 10 articles

Cover Story (view full-size image): End-of-life Li-ion batteries (LIBs) can be considered a valuable mine for some critical raw materials such as Co, Li, and graphite, in addition to other valuables such as Ni, Cu, and Mn. A successful story for developing and upscaling a pyrometallurgical process for efficient recycling of LIBs from lab to technical to pilot scale near to the commercial scale has been performed at SWERIM in the Re-Lion project financed by Swedish Energy Agency. Our study was conducted on the technical scale for the recycling of spent LIBs and the impact of graphite on valuable metals recovery from the battery black mass. It was possible to recover 98–99% of Co, Ni, and Cu, which is a great step for valorizing valuables from spent LIBs, saving virgin natural resources, and securing a sustainable LIB manufacture. View this paper
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9 pages, 20699 KiB  
Article
Evaluation of Vermicompost Produced by Using Post-Consumer Cotton Textile as Carbon Source
by Vijaypal Singh, Jordan Wyatt, Ali Zoungrana and Qiuyan Yuan
Recycling 2022, 7(1), 10; https://doi.org/10.3390/recycling7010010 - 21 Feb 2022
Cited by 4 | Viewed by 3707
Abstract
A large amount of textile waste is generated every year around the globe. The textile product made from natural fibers might be vermicomposted and used as fertilizer. The present study aimed to research an integrated system of pre-composting (pathogen kill) and vermicomposting with [...] Read more.
A large amount of textile waste is generated every year around the globe. The textile product made from natural fibers might be vermicomposted and used as fertilizer. The present study aimed to research an integrated system of pre-composting (pathogen kill) and vermicomposting with various levels of post-consumer cotton waste to determine if this addition has any effects on the composting process. A vermicompost bin was constructed and filled with feedstocks mixed with post-consumer cotton textile waste at a 25:1 C:N ratio, and operated for three months at approximately 70% moisture content, with four composting trials with 0 g (control), 100 g, 200 g, and 300 g of textile waste. The pre-composting stage reached a temperature ranging from 40 °C to 50 °C, able to neutralize the pathogens. All four trials resulted in final compost with C: N ratios around 14, proving that post-consumer cotton textile waste did not affect the vermicomposting process, and was successfully used as a carbon source by worms to produce a healthy and mature compost. This indicates a sustainable option for the recovery of textile waste that is being decomposed in landfills. Full article
(This article belongs to the Special Issue Recycling and Recovery of Biomass Materials II)
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14 pages, 6085 KiB  
Article
Intelligent and Real-Time Detection and Classification Algorithm for Recycled Materials Using Convolutional Neural Networks
by Dimitris Ziouzios, Nikolaos Baras, Vasileios Balafas, Minas Dasygenis and Adam Stimoniaris
Recycling 2022, 7(1), 9; https://doi.org/10.3390/recycling7010009 - 18 Feb 2022
Cited by 15 | Viewed by 6265
Abstract
In recent years, the production of municipal solid waste has constantly been increasing. Recycling is becoming more and more important, as it is the only way that we can have a clean and sustainable environment. Recycling, however, is a process that is not [...] Read more.
In recent years, the production of municipal solid waste has constantly been increasing. Recycling is becoming more and more important, as it is the only way that we can have a clean and sustainable environment. Recycling, however, is a process that is not fully automated; large volumes of waste materials need to be processed manually. New and novel techniques have to be implemented in order to manage the increased volume of waste materials at recycling factories. In this paper, we propose a novel methodology that can identify common waste materials as they are being processed on a moving belt in waste collection facilities. An efficient waste material detection and classification system is proposed, which can be used in real integrated solid waste management systems. This system is based on a convolutional neural network and is trained using a custom dataset of images, taken on site from actual moving belts in waste collection facilities. The experimental results indicate that the proposed system can outperform existing algorithms found in the literature in real-world conditions, with 92.43% accuracy. Full article
(This article belongs to the Special Issue Feature Papers in Recycling 2021)
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16 pages, 2600 KiB  
Article
Physicochemical and Biological Contribution of Native Macrophytes in the Constructed Wetlands to Treat Municipal Wastewater: A Pilot-Scale Experiment in a Sub-Tropical Climate Region
by Tofeeq Aalam, Carlos Alberto Arias and Nadeem Khalil
Recycling 2022, 7(1), 8; https://doi.org/10.3390/recycling7010008 - 17 Feb 2022
Cited by 2 | Viewed by 2333
Abstract
In this study, the physicochemical and biological contributions of different macrophytes in horizontal sub-surface flow constructed wetlands (HSSF-CWs) to treat low-strength municipal wastewater operated at high hydraulic loads under a sub-tropical climatic region is investigated. Out of the four identical beds, three were [...] Read more.
In this study, the physicochemical and biological contributions of different macrophytes in horizontal sub-surface flow constructed wetlands (HSSF-CWs) to treat low-strength municipal wastewater operated at high hydraulic loads under a sub-tropical climatic region is investigated. Out of the four identical beds, three were planted with locally available macrophytes (P. australis, Sagittaria, and Iris), whereas one bed was kept as a control. The beds were filled with media and operated in parallel continuously for eight months, with increasing the surface loading rate (SLR) from 0.19 to 2.78 m day−1. The results indicate that the planted beds performed significantly (p < 0.01) better to remove TSS (70% to 78%), BOD5 (66% to 77%), COD (59% to 75%), NO3-N (56% to 64%), NH4-N (41% to 69%), TN (36% to 41%), and TP (44% to 61%) as compared to the unplanted bed for the same parameters (48%, 39%, 40%, 33%, 18%, 20%, and 29%, respectively). The presence of macrophytes in HSSF-CWs was found to be highly significant. The average relative growth rate (RGR) was observed in the order of P. australis (0.0086 day−1) > Sagittaria (0.0061 day−1) > Iris (0.0059 day−1). When compared to the performances of the species used, Sagittaria and P. australis produced better results than Iris. The investigations on biomass showed that Sagittaria yielded higher production, followed by P. australis and Iris. The proportions of uptake by the macrophytes were found to be 9.3%, 6.3%, and 3.9% of mass N removal, and 7.6%, 5.1%, and 4.4% of mass p removal in Sagittaria, P. australis, and Iris, respectively. This study contributes to the effective response to the environment, which validates a major role of macrophytes and their disparate response to pollutant removal processes by different species from municipal wastewater through HSSF-CWs. Full article
(This article belongs to the Special Issue Reuse of Wastewater: Recovery of Water, Nutrients, and Energy)
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15 pages, 1862 KiB  
Article
Energy Potential Assessment of Excavated Landfill Material: A Case Study of the Perm Region, Russia
by Iuliia Shcherbinina, Stepan Polygalov, Galina Ilinykh, Vladimir Korotaev, Natalia Sliusar, Ivana Mihajlovic and Nemanja Stanisavljevic
Recycling 2022, 7(1), 7; https://doi.org/10.3390/recycling7010007 - 15 Feb 2022
Cited by 1 | Viewed by 3102
Abstract
The paper presents results of field and laboratory studies of thermal characteristics to excavated landfill waste in Perm region, Russia. The peculiarity of the study includes the following aspects: waste composition with a high share of polymers, the climatic conditions of the territory [...] Read more.
The paper presents results of field and laboratory studies of thermal characteristics to excavated landfill waste in Perm region, Russia. The peculiarity of the study includes the following aspects: waste composition with a high share of polymers, the climatic conditions of the territory and the lack of engineering infrastructure at the waste disposal facility. When determining the waste composition and thermal properties of waste, it is proposed to include a stage of removal of contamination from landfilled waste fraction, since their share of contamination can reach up to 33%. This stage will allow researchers to adjust the net calorific value of the excavated waste without overestimation, which may affect decision-making when implementing waste management technology. Among combustible components with the highest moisture content are waste paper (69.1%) and diapers (65.8%), whereas wood (11.2%), PET bottles (3.1%) and other 3D plastics (13.4%) have rather low ash content on a dry basis. Calculation of thermal properties and analysis of the energy potential of the waste samples was conducted based on the obtained data. The calorific value of the individual components and excavated waste depends not only on the moisture and ash content of the individual components, but also on the presence of contaminants. The average net calorific value of the excavated waste is 4.9 MJ/kg, and for the separate mixture of combustible components, it is 7.5 MJ/kg at a moisture content of 44%. Excavated landfill waste can be regarded as a resource for the manufacture of secondary fuel only after pretreatment that includes at least sorting and drying. The results of this study may be useful in developing technologies needed to eliminate old MSW dumps and old landfills, for the development of the concept of circular economy and prevention of environmental degradation problems. Full article
(This article belongs to the Special Issue From Waste to Energy—Challenges and Opportunities)
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13 pages, 2126 KiB  
Article
Embodied Energy in Pyrolysis and Solvolysis Approaches to Recycling for Carbon Fiber-Epoxy Reinforced Composite Waste Streams
by Komal Kooduvalli, John Unser, Soydan Ozcan and Uday K. Vaidya
Recycling 2022, 7(1), 6; https://doi.org/10.3390/recycling7010006 - 14 Feb 2022
Cited by 12 | Viewed by 5879
Abstract
Carbon fiber composites are increasingly used in aerospace, motorcycles, sporting, and high-performance vehicles, and their end of life recycling is of growing interest. This study deals with the life cycle assessment (LCA) of carbon fiber reinforced plastics (CFRP) waste streams. The embodied energy [...] Read more.
Carbon fiber composites are increasingly used in aerospace, motorcycles, sporting, and high-performance vehicles, and their end of life recycling is of growing interest. This study deals with the life cycle assessment (LCA) of carbon fiber reinforced plastics (CFRP) waste streams. The embodied energy (EE) of recycling CFRP via two viable methods—i.e., pyrolysis and solvolysis—is studied. Both pyrolysis and solvolysis were studied for EE with different variants. Alongside fiber recovery from CFRP, the pyrolysis process calculations consider energy recovery from syngas and oil produced within the system. For pyrolysis, electric furnace and natural gas were primarily considered. For solvolysis, different solvent scenarios were considered, including (a) deionized water, (b) water and potassium hydroxide, (c) acetone and water, and (d) water with acetic acid and potassium hydroxide. Energy reduction from one generation to the next has also been highlighted. The EE for recycling CFRP is quantified and discussed for these scenarios in this paper. Full article
(This article belongs to the Special Issue Advances in the Recycling and Processing of Plastic Waste)
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15 pages, 3821 KiB  
Article
Effect of Graphite on the Recovery of Valuable Metals from Spent Li-Ion Batteries in Baths of Hot Metal and Steel
by Elsayed Mousa, Xianfeng Hu and Guozhu Ye
Recycling 2022, 7(1), 5; https://doi.org/10.3390/recycling7010005 - 03 Feb 2022
Cited by 4 | Viewed by 3559
Abstract
The recycling of valuable metals from spent lithium-ion batteries (LIBs) is highly important to secure the sustainable production of new LIBs and reduce the dependence on virgin resources. The present paper aims to study the smelting behaviour of black mass (BM) from spent [...] Read more.
The recycling of valuable metals from spent lithium-ion batteries (LIBs) is highly important to secure the sustainable production of new LIBs and reduce the dependence on virgin resources. The present paper aims to study the smelting behaviour of black mass (BM) from spent LIBs and investigate the effect of graphite on metal recovery in a carbon-saturated hot metal bath and in a low-carbon steel bath. The smelting trials of BM were conducted in a technical scale (150 kg) induction furnace using hot metal and steel scrap at operating temperatures in the range of 1278–1438 °C and 1470–1610 °C, respectively. Two grades of BM were applied in the current study; high-Ni BM and high-Co BM. Parts of both grades of the BM were briquettes to enhance the direct reduction of metal oxides with embedded graphite and to reduce the dust generation during loading into the furnace. The briquette BM was charged to carbon-saturated hot metal bath while the other part of the BM was subjected to de-coking in a muffle furnace in an oxidising atmosphere to remove graphite (37–39%) and to concentrate the valuable metals in the BM. The de-coked BM was loaded directly, without the need for the briquette, to the low-carbon steel bath. The results indicated that smelting of the de-coked BM in a steel bath is more efficient in metal recovery than the smelting of the corresponding briquette BM in a molten hot metal bath. The highest recovery rate of Co, Ni and Cu (98–99%) was obtained by smelting de-coked high-Co BM in a low-carbon molten steel bath, while the lowest recovery rate (38–55%) was obtained by smelting the briquette high-Ni BM in the carbon-saturated hot metal bath. Full article
(This article belongs to the Special Issue Recycling of Lithium Ion Batteries and Other Next Generation Materials)
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16 pages, 3373 KiB  
Article
Critical Evaluation of the Potential of Organic Acids for the Environmentally Friendly Recycling of Spent Lithium-Ion Batteries
by Eva Gerold, Clemens Schinnerl and Helmut Antrekowitsch
Recycling 2022, 7(1), 4; https://doi.org/10.3390/recycling7010004 - 31 Jan 2022
Cited by 17 | Viewed by 5136
Abstract
The need to recover valuable metals from spent lithium-ion batteries (LIBs) is undisputed. However, the environment and the climate are also affected by emissions from the recycling processes. Therefore, the call for environmentally friendly recycling methods is currently louder than ever. In the [...] Read more.
The need to recover valuable metals from spent lithium-ion batteries (LIBs) is undisputed. However, the environment and the climate are also affected by emissions from the recycling processes. Therefore, the call for environmentally friendly recycling methods is currently louder than ever. In the field of hydrometallurgical recovery of metals from spent LIBs, inorganic acids have so far proved to be an effective, but environmentally problematic, leaching agent, since the pollution of wastewater by high salt loads and the emission of toxic gases cannot be avoided. This has recently led to a trend towards the application of organic acids, as these have significantly more environmentally friendly properties. In order to continue this approach, and to improve it even further from an environmental point of view, this work focuses on the utilization of low leaching temperatures in combination with organic acids for the recovery of valuable metals from spent lithium-ion batteries. This can drastically reduce the required energy demand. Furthermore, attention is paid to higher (50–100 g·L−1) solid-liquid ratios, which are indispensable, especially with regard to the economic establishment of the tested process. The experimental verification of the feasibility using citric, oxalic, and formic acid showed the possibility of an efficient recovery of cobalt, nickel, and lithium. In particular, citric acid in combination with hydrogen peroxide as a reducing agent appears to be a suitable and environmentally friendly alternative to classical inorganic acids, even at low process temperatures, for the hydrometallurgical recycling of lithium-ion batteries. Full article
(This article belongs to the Special Issue Recycling of Lithium Ion Batteries and Other Next Generation Materials)
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3 pages, 162 KiB  
Editorial
Acknowledgment to Reviewers of Recycling in 2021
by Recycling Editorial Office
Recycling 2022, 7(1), 3; https://doi.org/10.3390/recycling7010003 - 20 Jan 2022
Viewed by 1939
Abstract
Rigorous peer-reviews are the basis of high-quality academic publishing [...] Full article
12 pages, 883 KiB  
Article
Baseline Data of Low-Density Polyethylene Continuous Pyrolysis for Liquid Fuel Manufacture
by Aleksandr Ketov, Vladimir Korotaev, Natalia Sliusar, Vladivir Bosnic, Marina Krasnovskikh and Aleksei Gorbunov
Recycling 2022, 7(1), 2; https://doi.org/10.3390/recycling7010002 - 12 Jan 2022
Cited by 3 | Viewed by 3146
Abstract
The recycling of end-of-life plastics is a problem, since small parts can be returned into circulation. The rest is burned, landfilled or recycled into low-quality heating oil by pyrolysis methods. The disadvantages of this method are the need to dispose the formed by-product, [...] Read more.
The recycling of end-of-life plastics is a problem, since small parts can be returned into circulation. The rest is burned, landfilled or recycled into low-quality heating oil by pyrolysis methods. The disadvantages of this method are the need to dispose the formed by-product, pyrolytic carbon, the poor quality of produced liquid fuel and the low productivity of the method associated with the periodicity of the process. In this work, methods of thermogravimetry and chromatography–mass spectrometry (GC-MS) have been used to study the co-pyrolysis products of low-density polyethylene (LDPE) and oxygen-containing substances at the pressures of 4–8 MPa and temperatures of 520–620 °C. Experiments have highlighted the conditions needed for producing of high-quality liquid fuel. Initial data have been prepared for the design of a continuous pyrolysis reactor to dispose polymer waste for the production of bio-oil which would be available to enter the petrochemical products market. Full article
(This article belongs to the Special Issue From Waste to Energy—Challenges and Opportunities)
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15 pages, 4719 KiB  
Article
An Empirical Study on the Main Determinants of Recycling Plastic Waste in Tunisia
by Lamia Ben Amor and Sami Hammami
Recycling 2022, 7(1), 1; https://doi.org/10.3390/recycling7010001 - 06 Jan 2022
Cited by 2 | Viewed by 4357
Abstract
Over the past fifteen years, numerous policies for recycling and recovering waste have been implemented throughout the world. Tunisia is among the countries considering recycling as a sustainable development path. This empirical study aimed to investigate and examine the influence of financial determinants [...] Read more.
Over the past fifteen years, numerous policies for recycling and recovering waste have been implemented throughout the world. Tunisia is among the countries considering recycling as a sustainable development path. This empirical study aimed to investigate and examine the influence of financial determinants measured by the price of waste disposal (PDI), institutional determinants measured by the collection of waste (CW) and the number of drop-off recycling centers, and ordinance and demographic determinants measured by the population density and the recycling rate for plastic as a domestic waste based on a panel of 24 Tunisian governorates over the 2001–2020 period. It is concluded from the empirical findings that all exogenous variables except population density have a significant effect on the recycling rate. Full article
(This article belongs to the Special Issue Advances in the Recycling and Processing of Plastic Waste)
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