Special Issue "Feature Papers in Recycling 2021"

A special issue of Recycling (ISSN 2313-4321).

Deadline for manuscript submissions: closed (31 March 2022) | Viewed by 27264

Special Issue Editors

Prof. Dr. Francesco Paolo La Mantia
E-Mail Website
Guest Editor
Department of Engineering, University of Palermo, RU INSTM, Viale delle Scienze, 90128 Palermo, Italy
Interests: polymer processing; mechanical behaviour of polymer-based systems; rheological behaviour of polymer-based systems; green composites; biocomposites; nanocomposites; biodegradable polymers; polymer blends; degradation and recycling of polymer-based systems
Special Issues, Collections and Topics in MDPI journals
Dr. Beatrice Castellani
E-Mail Website
Guest Editor
Department of Engineering, CIRIAF, University of Perugia, Via G.Duranti 67, 06125 Perugia, Italy
Interests: energy storage and energy systems; natural gas hydrates; clathrate hydrates; CO2 capture; energy efficiency; waste management
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

It is our pleasure to announce a new Special Issue entitled “Feature Papers in Recycling 2021.” This is a collection of important high-quality papers (original research articles or comprehensive review papers) published in open access format by prominent scholars. Recycling is a peer-reviewed scientific journal in the area of waste reutilization and resource recycling. It provides an international online forum for studies related to recycling, resource recovery and waste utilisation across many industries, including glass, paper, metal, plastic, textiles, and electronics. We intend for this issue to be the best forum for disseminating excellent research findings, as well as sharing innovative ideas in the field.

In this Special Issue, we aim to collect contributions in the main fields covered by the journal:·      

Resource recycling

Waste processing technologies·      

Circular economy·      

Zero waste programs·      

Environmental and social impact of recycling·      

Product (eco) design and recycling

Prof. Dr. Francesco Paolo La Mantia
Dr. Beatrice Castellani
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Recycling is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Metal recycling
  • Polymers recycling
  • Biomass recycling
  • Chemicals recycling
  • E-waste recycling
  • Energy recycling
  • Waste management
  • Recycling policies
  • The economics of recycling

Published Papers (18 papers)

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Editorial

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Editorial
Special Issue “Feature Papers in Recycling 2021”
Recycling 2022, 7(4), 56; https://doi.org/10.3390/recycling7040056 - 11 Aug 2022
Viewed by 386
Abstract
Recycling is the collection and conversion process of waste materials into second raw materials [...] Full article
(This article belongs to the Special Issue Feature Papers in Recycling 2021)

Research

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Article
The Physical Characterization and Terminal Velocities of Aluminium, Iron and Plastic Bottle Caps in a Water Environment
Recycling 2022, 7(3), 28; https://doi.org/10.3390/recycling7030028 - 22 Apr 2022
Cited by 1 | Viewed by 1191
Abstract
Aluminium, iron and plastic are materials which are extensively used at both industry and individual levels. However, significant amounts of aluminium, iron and plastic end up in the environment. Specifically, bottle caps made of these materials are often thrown away, with or without [...] Read more.
Aluminium, iron and plastic are materials which are extensively used at both industry and individual levels. However, significant amounts of aluminium, iron and plastic end up in the environment. Specifically, bottle caps made of these materials are often thrown away, with or without bottles, and appear among the common plastic debris entering the world’s oceans and beaches. More than 20 million bottle caps and lids have been identified during beach-cleaning campaigns over the last 30 years. To recover bottle caps from the shores, conventional technologies can be used. In this paper, the physical properties of used metal and plastic bottle caps were examined and related to the settling and rising velocities of the caps, as well as their drag coefficients and hydrodynamic modes in water environments, with respect to gravity separation. The sample contained aluminium, iron, high-density polyethylene (HDPE), low-density polyethylene (LDPE), and polypropylene (PP) bottle caps. The findings revealed that the density differences between the bottle caps resulted in the terminal settling velocities of aluminium and iron particles, which were significantly higher than the rising velocities of the plastic caps. The results allowed us to design a flowsheet for bottle cap recovery from beach coasts in order to reduce environmental impact and produce add-on plastic and metal products. Full article
(This article belongs to the Special Issue Feature Papers in Recycling 2021)
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Article
Intelligent and Real-Time Detection and Classification Algorithm for Recycled Materials Using Convolutional Neural Networks
Recycling 2022, 7(1), 9; https://doi.org/10.3390/recycling7010009 - 18 Feb 2022
Cited by 3 | Viewed by 1422
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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Article
Recycling of Waste Fiber-Reinforced Plastic Composites: A Patent-Based Analysis
Recycling 2021, 6(4), 72; https://doi.org/10.3390/recycling6040072 - 05 Nov 2021
Cited by 5 | Viewed by 1345
Abstract
Fiber-reinforced plastic composite materials are increasingly used in many industrial applications, leading to an increase in the amount of waste that must be treated to avoid environmental problems. Currently, the scientific literature classifies existing recycling technologies into three macro-categories: mechanical, thermal, and chemical; [...] Read more.
Fiber-reinforced plastic composite materials are increasingly used in many industrial applications, leading to an increase in the amount of waste that must be treated to avoid environmental problems. Currently, the scientific literature classifies existing recycling technologies into three macro-categories: mechanical, thermal, and chemical; however, none are identified as superior to the others. Therefore, scholars and companies struggle to understand where to focus their efforts. Patent analysis, by relying on quantitative data as a precursor to new technological developments, can contribute to fully grasping current applications of each recycling technology and provide insights about their future development perspectives. Based on these premises, this paper performs a patent technology roadmap to enhance knowledge about prior, current, and future use of the main recycling technologies. The results show that recycling macro-categories have different technology maturity levels and growth potentials. Specifically, mechanical recycling is the most mature, with the lowest growth potential, while thermal and chemical recycling are in their growth stage and present remarkable future opportunities. Moreover, the analysis depicts several perspectives for future development on recycling technologies applications within different industries and underline inter- and intra-category dependencies, thus providing valuable information for practitioners and both academic and non-academic backgrounds researchers interested in the topic. Full article
(This article belongs to the Special Issue Feature Papers in Recycling 2021)
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Article
The Impact of a Rural School-Based Solid Waste Management Project on Learners’ Perceptions, Attitudes and Understanding of Recycling
Recycling 2021, 6(4), 71; https://doi.org/10.3390/recycling6040071 - 03 Nov 2021
Cited by 1 | Viewed by 1232
Abstract
Continued environmental degradation necessitates innovative strategies to improve society’s attitude towards and understanding of recycling solid waste. Previous research has shown that school-based projects integrated into the school curriculum could effectively enhance learners’ knowledge of recycling and attitudes towards recycling. However, not much [...] Read more.
Continued environmental degradation necessitates innovative strategies to improve society’s attitude towards and understanding of recycling solid waste. Previous research has shown that school-based projects integrated into the school curriculum could effectively enhance learners’ knowledge of recycling and attitudes towards recycling. However, not much is known about the impact of such projects if they are driven by learners, particularly in under-resourced rural schools. Therefore, in the current research, we aimed to determine the impact of a school-based recycling project, integrated as practical work, on learners’ understanding of recycling, their attitude towards recycling, and the perceived impact of the project on the school environment, in an under-resourced rural school. Our findings showed that participating in a rural school-based recycling project may not enhance Grade 7 Natural Sciences learners’ perceptions of, attitudes towards, and understanding of recycling. We posit that various factors may affect the effectiveness of a recycling project. Further research is required to explore these factors further. Full article
(This article belongs to the Special Issue Feature Papers in Recycling 2021)
Article
A Multiplatform BIM-Integrated Construction Waste Quantification Model during Design Phase. The Case of the Structural System in a Spanish Building
Recycling 2021, 6(3), 62; https://doi.org/10.3390/recycling6030062 - 15 Sep 2021
Cited by 5 | Viewed by 1580
Abstract
Construction waste (CW) is a prime contributor to the stream of total waste worldwide. One of the biggest challenges of the construction industry is to minimise CW and to develop practices of a more sustainable nature for its management and recycling in order [...] Read more.
Construction waste (CW) is a prime contributor to the stream of total waste worldwide. One of the biggest challenges of the construction industry is to minimise CW and to develop practices of a more sustainable nature for its management and recycling in order to promote its transition towards a more effective circular economy. The implementation of these practices contributes towards mitigating the scarcity of natural resources and the environmental impact of CW. Thus, a preceding and essential step is the estimation of CW during building design, which will allow the adoption of measures for its early reduction and optimisation. For this purpose, Building Information Modelling (BIM) has become a useful methodology to predict waste during the early stages of design. There remains, however, a lack of instrumental development. Therefore, this study proposes a BIM-based method to estimate CW during building design by integrating a consolidated construction waste quantification model in three different BIM platforms. For its validation, the method is applied to the structural system of a Spanish residential building. The results provide evidence that the proposed method is vendor-neutral and enables the automatic identification and quantification of the waste generated by each building element during the design stage in multiple BIM platforms. Full article
(This article belongs to the Special Issue Feature Papers in Recycling 2021)
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Article
Cost Analysis of Various Factors for Geopolymer 3D Printing of Construction Products in Factories and on Construction Sites
Recycling 2021, 6(3), 60; https://doi.org/10.3390/recycling6030060 - 08 Sep 2021
Cited by 5 | Viewed by 1304
Abstract
The utilization of geopolymer 3D printing for construction products in recent years has been exceptionally substantial, owing to their low carbon dioxide emissions, high-performance properties such as durability, and good thermal and mechanical properties. This automated manufacturing process reduces the need for additional [...] Read more.
The utilization of geopolymer 3D printing for construction products in recent years has been exceptionally substantial, owing to their low carbon dioxide emissions, high-performance properties such as durability, and good thermal and mechanical properties. This automated manufacturing process reduces the need for additional formworks, capital investments, and human resources. Geopolymer 3D printing development is emerging because of its advanced use in construction applications. However, high costs of the initial stages of geopolymer production and 3D printing has inhibited the development of this technology in many countries. This research presents a comprehensive economic evaluation of the investment for each principal stage that facilitates a better deployment of the resources. The study investigated all phases of geopolymer production, from the extraction of raw materials to printing. The cost for the four fundamental stages, namely raw material availability and transportation, pretreatments for raw materials, parameter selection and strength requirements, and printing in factories and on construction sites, were analyzed. The results show that 3D printing of a geopolymer on a construction site is economically more advantageous compared to printing in the factory. The study also verified that raw material transportation cost has the least effect on the finished product cost, whereas pretreatments of raw material and mixing parameters significantly influenced the ultimate cost of the product. Finally, research work suggested the need for future tasks to make geopolymer 3D printing a viable construction approach. Full article
(This article belongs to the Special Issue Feature Papers in Recycling 2021)
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Article
Characterising Radioactive Caesium Leaching from Incineration Ash of Municipal Solid Waste in Fukushima and the Inhibitory Effect of Acid Clay
Recycling 2021, 6(3), 56; https://doi.org/10.3390/recycling6030056 - 29 Aug 2021
Cited by 1 | Viewed by 1014
Abstract
Following the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident caused by the 2011 Tōhoku earthquake and tsunami, radioactive caesium (r-Cs) was detected in the ash generated by municipal solid waste (MSW) incineration facilities in Fukushima Prefecture. This has led to concerns of r-Cs [...] Read more.
Following the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident caused by the 2011 Tōhoku earthquake and tsunami, radioactive caesium (r-Cs) was detected in the ash generated by municipal solid waste (MSW) incineration facilities in Fukushima Prefecture. This has led to concerns of r-Cs leaching and subsequent environmental contamination during recycling or landfill disposal. Therefore, it is crucial that the relevant authorities have a thorough understanding of r-Cs leaching behavior to establish suitable prevention methods. In this study, we collected r-Cs-contaminated fly and bottom ash (FA and BA) samples from five MSW incineration facilities in Fukushima Prefecture and conducted tests to clarify their basic physical properties and r-Cs leaching properties. We also examined the possibility of preventing r-Cs leaching by adding 5 wt% acid clay to the FA. FA had greater chloride content and r-Cs leaching rate than BA and was found to absorb moisture and deliquesce when stored under high-humidity conditions. However, the addition of acid clay effectively prevented r-Cs leaching upon contact with moisture. From the results, we propose some specific recommendations to counter the leaching of r-Cs from FA at MSW incineration facilities, which will limit r-Cs leaching during recycling or landfill processes. Full article
(This article belongs to the Special Issue Feature Papers in Recycling 2021)
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Article
Sustainability Assessment of Reuse and Recycling Management Options for End-of-Life Computers-Korean and Japanese Case Study Analysis
Recycling 2021, 6(3), 55; https://doi.org/10.3390/recycling6030055 - 26 Aug 2021
Cited by 2 | Viewed by 1118
Abstract
The depletion of natural resources and global warming have increased in severity globally. In the industrial field, assembly products, such as electronic products, should be disassembled for recycling and reuse to deal with these problems. Reuse and recycling can contribute to reducing GreenHouse [...] Read more.
The depletion of natural resources and global warming have increased in severity globally. In the industrial field, assembly products, such as electronic products, should be disassembled for recycling and reuse to deal with these problems. Reuse and recycling can contribute to reducing GreenHouse Gas (GHG) emissions and less depletion of natural resources since GHG emissions for virgin material production can be saved using reused components and recycled materials. However, each component of selling revenue and material-based GHG emissions depends on the country because of the different energy mixes of electrical power. Moreover, each collected component embedded in End-of-Life (EOL) products needs to be selected as a life cycle option based on its remaining life. The purpose of this study is to decide life cycle options such as reuse, recycling, and disposal of each component environmentally-friendly and economically in Korea and Japanese cases for computers. Firstly, selecting the life cycle option for each component was formulated by 0–1 integer programming with ε constraints. Next, GHG emissions, profits, and costs in Korea and Japan were estimated and analyzed for each component. Finally, Korean and Japanese cases were analyzed to obtain an economic value in the same material-based GHG saving rate with each component’s life cycle option selection by comparing each EOL product data. In the experiments, GHG recovery efficiency was higher in Japan 43 [g/Yen] than one in Korea 28 [g/Yen]. Therefore, it was better to retrieve and reutilize the components in Korea. However, if the maximum GHG recovery efficiency is desired, Japan is a better option. Full article
(This article belongs to the Special Issue Feature Papers in Recycling 2021)
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Article
Rheological, Mechanical and Morphological Characterization of Monopolymer Blends Made by Virgin and Photo-Oxidized Polypropylene
Recycling 2021, 6(3), 51; https://doi.org/10.3390/recycling6030051 - 16 Jul 2021
Cited by 2 | Viewed by 1235
Abstract
In this work, monopolymer blends of virgin polypropylene and photo-oxidized polypropylene were prepare and characterized. The polypropylene samples were subjected to accelerated ageing to simulate the effects of outdoor exposure of polypropylene. After exposure, samples were pelletized and mixed with the same virgin [...] Read more.
In this work, monopolymer blends of virgin polypropylene and photo-oxidized polypropylene were prepare and characterized. The polypropylene samples were subjected to accelerated ageing to simulate the effects of outdoor exposure of polypropylene. After exposure, samples were pelletized and mixed with the same virgin polymer. The rheological, mechanical and morphological characterization was conducted on both the polymers and the blends. Both viscosity and mechanical properties decrease with increases in the content of recycled, photo-oxidized components and of the level of degradation of this component. In addition, the experimental data were compared with a model that takes into account both the effect of the change of the molecular weight and of the presence of oxygenated groups. Full article
(This article belongs to the Special Issue Feature Papers in Recycling 2021)
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Article
A Gap Analysis of Ship-Recycling Practices in Indonesia
Recycling 2021, 6(3), 48; https://doi.org/10.3390/recycling6030048 - 13 Jul 2021
Cited by 3 | Viewed by 1721
Abstract
Ship recycling is gaining attention in Indonesia due to the increase in end-of-life ships and uneconomical nationally flagged ships, and is considered a prospective source of economic development and employment opportunity, and yet conceivably poses a threat to the health and safety of [...] Read more.
Ship recycling is gaining attention in Indonesia due to the increase in end-of-life ships and uneconomical nationally flagged ships, and is considered a prospective source of economic development and employment opportunity, and yet conceivably poses a threat to the health and safety of workers and the environment. There are international and national regulations that govern ship-recycling activities to ensure that the hazardous impacts of the industry are minimized. We investigated the disparity between current ship-breaking practices in Indonesia and the requirements of related international and national regulations, with the findings intended for use as a stepping stone to proposing a strategy to establish a green and sustainable ship-recycling industry. A benchmark study of the world’s leading ship-recycling countries was conducted, and a gap analysis was performed by comparing existing international and national regulations with current ship-breaking practices in Indonesia. We identified two types of ship-breaking practices in Indonesia: Conventional environmentally unfriendly ship-breaking method, conducted by most Indonesian ship-breaking yards, and a rather modern, more environmentally friendly method, conducted by ship-repair yards. However, neither of the practices met the requirements of the regulations, and improvements are therefore needed to make the ship-recycling industry more green and sustainable, and to gain international recognition. Full article
(This article belongs to the Special Issue Feature Papers in Recycling 2021)
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Article
Using Artificial Intelligence for Optimizing Natural Frequency of Recycled Concrete for Mechanical Machine Foundation
Recycling 2021, 6(3), 43; https://doi.org/10.3390/recycling6030043 - 23 Jun 2021
Cited by 3 | Viewed by 1236
Abstract
This paper investigates the mechanical properties of two different types of recycled concrete, which use wood and rubber, relative to those characteristics of pure concrete, in terms of maximum load and natural frequencies. This paper contributes to the state of the art in [...] Read more.
This paper investigates the mechanical properties of two different types of recycled concrete, which use wood and rubber, relative to those characteristics of pure concrete, in terms of maximum load and natural frequencies. This paper contributes to the state of the art in this area in a number of ways. Firstly, the paper provides furtherance to the progressively growing literature in the field of recycled concrete and mechanical properties of materials. Secondly, the paper investigates the mechanical properties of two different types of recycled concrete by means of investigating the natural frequency of the samples, which is a new contribution. Lastly, the results from predicting the natural frequencies of concrete using fuzzy logic have been effectively assessed and compared with the analytical results. Results from the study show that the pure concrete samples produced maximum natural frequency, then concrete samples with wood, and lastly, concrete samples with rubber. The tolerance between the lab test results and fuzzy logic is approximately 5%. These results could have significant implications for furthering recycled concrete research and for designing machine foundations. Evidence of the applicability of fuzzy logic as a predictive and analysis tool for the mechanical properties of recycled concrete are discussed. Full article
(This article belongs to the Special Issue Feature Papers in Recycling 2021)
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Article
Appraisal of Households’ Knowledge and Perception towards E-Waste Management in Limpopo Province, South Africa
Recycling 2021, 6(2), 39; https://doi.org/10.3390/recycling6020039 - 11 Jun 2021
Cited by 2 | Viewed by 1585
Abstract
The generation of electronic waste (e-waste) is increasing at an alarming rate in South Africa. This waste stream is also emanating from household appliances due to beneficial attributes accrued to the use of these electronic devices. At the same time, these devices are [...] Read more.
The generation of electronic waste (e-waste) is increasing at an alarming rate in South Africa. This waste stream is also emanating from household appliances due to beneficial attributes accrued to the use of these electronic devices. At the same time, these devices are a source of concern considering the environmental impacts as well the threat of health hazards they possess to human wellbeing. In appraising household knowledge and perception on e-waste management in Limpopo Province of South Africa, 200 semi-structured, self-administered questionnaires were used in eliciting data from the participants. The results indicated that 76% of the respondents believed that e-waste streams have negatively affected their environment. Additionally, 85% of the survey households are willing to pay for the proper disposal of their e-waste. Furthermore, the results indicated a statistically significance between gender and knowledge on e-waste management (p-value 0.003) while there was no statistically significant difference between gender and perception (p-value 0.318) on e-waste management. Based on the results, the study recommends awareness and educational campaigns as a step in changing the perception of households on e-waste and environmental consciousness. Full article
(This article belongs to the Special Issue Feature Papers in Recycling 2021)
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Article
Characterization of Cytisus striatus (Hill) Rothm.: Waste Biomass Energy Recovery as a Measure to Reduce the Risk of Rural Fires
Recycling 2021, 6(2), 36; https://doi.org/10.3390/recycling6020036 - 07 Jun 2021
Cited by 3 | Viewed by 1342
Abstract
Shrub species play a critical ecological role in ecosystems, covering significant areas. However, with the current development of vegetation cover, conditioned by climate change, certain species have acquired a dominant role, which suffocates the other ecosystem species in a natural monoculture model. Thus, [...] Read more.
Shrub species play a critical ecological role in ecosystems, covering significant areas. However, with the current development of vegetation cover, conditioned by climate change, certain species have acquired a dominant role, which suffocates the other ecosystem species in a natural monoculture model. Thus, some species, such as Cytisus striatus (Hill) Rothm., have acquired preponderance, mainly due to the dense forests they establish. This situation has contributed to the increased risk of rural fires, forcing permanent actions to control the settlements. These actions entail costs that make the continuity and permanence of control unsustainable. The energetic valorization of residual biomass resulting from operations to reduce fuel load is an option that seems viable, mainly if used in the production of biomass pellets in a mixture with other biomasses, such as Pinus pinaster or Eucalyptus globulus. The laboratory characterization tests demonstrated that the residual biomass of C. striatus presents parameters that fall within limits defined by the standard ENPlus®. The processing of this residual biomass on an industrial scale line is also feasible. However, given the configuration of the material to be processed, production lines may be necessary, especially concerning the detachment of the material. The logistical issue may also impose restrictions since the material has a low density, even when baled. Full article
(This article belongs to the Special Issue Feature Papers in Recycling 2021)
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Review

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Review
Comparison of Properties with Relevance for the Automotive Sector in Mechanically Recycled and Virgin Polypropylene
Recycling 2021, 6(4), 76; https://doi.org/10.3390/recycling6040076 - 24 Nov 2021
Cited by 3 | Viewed by 1781
Abstract
Polypropylene (PP) has a high recycling potential. However, the properties of mechanically recycled PP (R-PP) have not been fully compared to those of virgin PP (V-PP). Therefore, in this study, properties of R-PP and V-PP were compared using data from recyclers, virgin plastic [...] Read more.
Polypropylene (PP) has a high recycling potential. However, the properties of mechanically recycled PP (R-PP) have not been fully compared to those of virgin PP (V-PP). Therefore, in this study, properties of R-PP and V-PP were compared using data from recyclers, virgin plastic suppliers, and the literature. The properties of recyclates could not be directly correlated either with the properties of the virgin polymers from which the recyclates were made or the recycling parameters. It was found that the MFR of R-PP was higher; MFR R-PP had a median value (m) of 11 g/10 min while MFR V-PP had a median value of 6.3 g/10 min (at 230 °C and with 2.16 kg). In terms of mechanical properties, in many cases R-PP exhibited stiffer and more brittle behavior, with a slightly higher Young’s modulus (ER-PP = 1400 and EV-PP = 1200 MPa), a reduced elongation at break (ɛbR-PP = 4 l.-% and ɛbV-PP = 83 l.-%), and notched charpy impact strength (NCISR-PP = 4.8 and NCISV-PP = 7.5 kJ/m2). However, the values for every property had a broad distribution. In addition to existing information from the literature, our research sheds fresh light on the variation of the characteristics of recycled polypropylenes presently on the market. Full article
(This article belongs to the Special Issue Feature Papers in Recycling 2021)
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Review
Challenges and Emerging Trends in Toner Waste Recycling: A Review
Recycling 2021, 6(3), 57; https://doi.org/10.3390/recycling6030057 - 29 Aug 2021
Cited by 5 | Viewed by 1639
Abstract
Toner waste is one of the major electronic waste materials posing serious environmental threat and health hazards. Globally, only about 20–30% of toner waste is recycled, while the remaining percentage is dumped in landfills. Recycling options are limited due to the desirably engineered [...] Read more.
Toner waste is one of the major electronic waste materials posing serious environmental threat and health hazards. Globally, only about 20–30% of toner waste is recycled, while the remaining percentage is dumped in landfills. Recycling options are limited due to the desirably engineered durability of toners, ascribed to a complicated composition of chemicals, carbon black, and plastic particles, which in turn creates critical challenges in recycling. The World Health Organization has classified toner waste as class 2B carcinogen due to its potential health hazard. In this review, the existing challenges in toner waste recycling are discussed from the perspective of environmental, health, and feasibility aspects. In parallel, the challenges have been opening up alternative strategies to recycle toner wastes. Emerging trends in toner waste recycling include transformation of toner waste into value-added products, utilization as raw material for nanomaterial synthesis, generation of composite electrodes for power generation/storage devices, integration into construction materials, and development of microwave absorbing composites. Considering the enormous volume of toner waste generated globally every year, better recycling and transformation strategies are needed immediately. A circular economy could be established in the future by transforming the enormous toner waste into a resource for other applications. For an effective management of toner waste in the future, an integrated approach involving policies and legislations, infrastructure for collection and treatment, and financial planning among the stakeholders is needed in addition to technological innovations. Full article
(This article belongs to the Special Issue Feature Papers in Recycling 2021)
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Review
Factors Affecting Mobile Waste Recycling through RSCM: A Literature Review
Recycling 2021, 6(2), 30; https://doi.org/10.3390/recycling6020030 - 08 May 2021
Cited by 5 | Viewed by 1954
Abstract
Mobile phone consumers have been motivated by the rapid growth of technology and encouraged to update their devices regularly to keep up with new innovations, architectures, and capabilities. Consequently, mobile/cell phone waste has risen significantly in the last decade. Due to their small [...] Read more.
Mobile phone consumers have been motivated by the rapid growth of technology and encouraged to update their devices regularly to keep up with new innovations, architectures, and capabilities. Consequently, mobile/cell phone waste has risen significantly in the last decade. Due to their small size, it is convenient for users to keep outdated or unused mobile phones at home or the office, rather than recycling them appropriately. A reverse supply chain (RSC) is one possible method of mitigating the questionable e-waste activity present in the ecosystem. RSC has been significant for the mobile phone industry, user states, analysts, and scholars. This paper reviews the available literature in the RSC management (RSCM) domain, along with its processes and strategies. The paper reviews 223 published scholarly papers in the domain of mobile phone waste recycling and investigates 22 papers related to factors influencing consumers’ intention with regard to electronic recycling, focusing on mobile devices, which contribute significantly to electronic waste management practices. Full article
(This article belongs to the Special Issue Feature Papers in Recycling 2021)
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Review
Recycling of Aseptic Beverage Cartons: A Review
Recycling 2021, 6(1), 20; https://doi.org/10.3390/recycling6010020 - 11 Mar 2021
Cited by 12 | Viewed by 2687
Abstract
Aseptic beverage cartons are multilayer polymer-coated paperboards with a layer of aluminum foil. Due to their multilayer structure it is commonly assumed that they cannot be recycled. This is not the case and this review details the multifarious processes that are used to [...] Read more.
Aseptic beverage cartons are multilayer polymer-coated paperboards with a layer of aluminum foil. Due to their multilayer structure it is commonly assumed that they cannot be recycled. This is not the case and this review details the multifarious processes that are used to recycle aseptic beverage cartons. Hydrapulping to recover the paper fibers that constitute 75% of the carton is the most widespread process, followed by the manufacture of construction materials such as boards and tiles which utilize the complete carton. A range of mechanical, chemical and thermal processes are used to separate the PolyAl (polyethylene and aluminum) residual that remains after the paper fibers have been recovered. The simplest process involves agglutination followed by extrusion to obtain pellets that can then be used in industrial and consumer products or combined with other materials such as lignocellulosic wastes. Chemical approaches involve the solubilization of polyethylene and the removal of aluminum. Various thermal processes have also been investigated and a novel microwave-induced pyrolysis process appears the most commercially viable. It is concluded that the focus in future years is likely to be on recycling cartons into construction materials where there is a theoretical yield of 100% compared with 75% for hydrapulping. Full article
(This article belongs to the Special Issue Feature Papers in Recycling 2021)
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