Feature Papers in Recycling 2022

Mobile phones are the most heavily utilised electronic devices on a global scale. Since they are relatively smaller than other electronic devices, unlike other electronic waste (e-waste), they are not disposed of properly. Hence, this study examines the factors influencing mobile phone users’ overall intention to recycle their mobile phones. The factors used originate from the theory of planned behaviour (TPB), but additional factors were also included, namely, perceived benefits and data security, to allow for a more in-depth analysis of customer behaviour. Partial least squares structural equation modelling (PLS-SEM) was employed to analyse 601 results from the United Arab Emirates (UAE) through a self-administered online survey. The results demonstrate that perceived benefits (whether environmental or financial) and perceived behavioural control possess the most statistically significant positive effects on the UAE mobile phone users’ intention to participate in reverse supply chain (RSC) processes such as refurbishing or recycling. The impacts of attitude and subjective norms were the second most positive influences. Meanwhile, only 7% of UAE mobile phone users were significantly impacted by data security in participating in RSC processes. Additionally, recycling intention had no noticeable mediation effect on the relationship among the TPB variables and the extended variables (namely, data security and perceived benefits) and mobile phone recycling behaviour. The study offers confidence to industrial players in implementing these particular factors in their reverse supply chain management (RSCM) systems to influence more users to return end-of-life (EOL) or end-of-use (EOU) mobile phones, which could, in return, assist in resource preservation and environmental protection. Full article

Compounding is the final processing step for quality adjustment and control before recycled thermoplastic polymer material can be introduced into production processes. Motivated by the need for higher recyclate shares, the research question is which quality problems recycling compounders are encountered in practice, where they occur, and which mitigation options might be reasonable. Therefore, an online survey with 20 recycling compounders based in Germany was conducted asking about typical processing steps and processed materials, test procedures for quality assurance, quality problems, and possibilities for reducing quality problems. Results show that compounders mainly name impurities and contaminations of the input material as challenging and the reason for quality problems. The study shows that the problems are not dependent on the material input type. Quality problems occur along the entire secondary value chain, with companies manufacturing components themselves being particularly affected. The composition determination of the input materials helps to minimize quality problems. Full article

The production and consumption of plastics, which is indispensable in our modern life, has caused severe environmental impacts. Hence, academics and policymakers have been advocating the circularity of plastics. The role of businesses—particularly manufacturing companies—is pivotal to ensuring the circularity of plastics. This study, therefore, attempted to investigate whether chief executives of manufacturing companies based in the EU are keen on the uptake of recycled plastic and, furthermore, whether the uptake of recycled plastic is a worthwhile business strategy. This study found that the attitude, subjective norms and perceived behavioral control of chief executives positively shape their behavioral intention toward the circularity of plastics. Furthermore, the behavioral intentions of chief executives positively influence the uptake of recycled plastic in manufacturing companies, which could consequently improve business performance. This study suggests measures to increase the uptake of recycled plastic among businesses. Full article

Mineral carbonation is a method in carbon capture and utilization (CCU) in which carbon dioxide reacts with natural or synthetic mineral phases to form carbonates. In this study, BOF slag consisting of alite, Ca₃SiO₅, belite, Ca₂SiO₄, melilite, (Ca,Na)₂(Mg,Al)^[4][Si₂O₇], brownmillerite, Ca(Fe,Al)₂O₅, calcium ferrite, Ca₂FeO₄ and Ca-, Mg- and Mn-bearing wuestite, (Mg,Ca,Mn,Fe)O, was crushed into different particle size fractions and exposed over various durations (1 d, 3 d, 9 d, 14 d, 24 d) at a grate to 120 °C hot off-gas with a CO₂ content of 25%. However, the total inorganic carbon (TIC) content never increases above the detection limit of 0.5% throughout the experimental duration. The determination of the carbonation depth using phenolphthalein does not reveal a homogeneous carbonation front, but an irregular carbonation. This observation was confirmed by microprobe analyses using elemental mapping. The solubility of the slag increases with increasing carbonation, e.g., the leachability of sulfate increases from 7.8 to 8270 mg/kg dry matter (DM), and of calcium from 940 to 3860 mg/kg DM. The leaching of environmentally relevant element varies: the leachable concentration of molybdenum increases from 0.017 mg/kg DM to 0.089 mg/kg DM, that of chromium remains constant (ca. 0.05 mg/kg DM) whereas that of vanadium decreases from 1.1 to 0.45 mg/kg. In summary, the chosen carbonation technology must be improved to enhance carbonate yield. Full article

This research investigated recycling of manufacturing NdFeB magnet wastes in as-sintered and powder forms which contained high carbon via pyro-hydro metallurgy process. Effects of oxidative roasting on selective leaching of the magnet wastes were the main focus in comparison to recycling via whole leaching without oxidative roasting. The process started from oxidative roasting at 600 °C, sulfuric leaching, drying, roasting at 750 °C for powder and 800 °C for sintered wastes, water leaching, oxalic acid precipitation and calcination at 1000 °C to obtain neodymium oxides. Oxidative roasting was found to reduce carbon and resulted in neodymium and iron oxide formation with a minimum amount of neodymium iron oxide. This provided effective selective leaching of neodymium. For whole leaching, a significant loss of neodymium into leached residue was observed. Oxidative roasting-selective leaching provided significant recovery in the amount of 75.46% while whole leaching resulted in only 31.62 wt.% in the case of sintered waste. The final composition via oxidative roasting-selective leaching consisted of 68.11 wt.% neodymium, 19.83 wt.% praseodymium and 0.31 wt.% iron, while whole leaching resulted in a higher amount of iron at 1.20 wt.%. Similar results were obtained for powder magnet waste. Full article

Few prior studies have examined the social and environmental consequences of waste generation and recycling, resulting in a policy gap in the sustainability agenda. The research filled a knowledge vacuum in the literature by investigating the environmental repercussions of different waste generation and recycling processes in the Chinese economy. The study analyzed waste production and recycling statistics over the last 46 years, from 1975 to 2020, and their impact on the nation’s emissions per capita. This study used four primary approaches to determine the links between the examined variables, beginning with the unit root test, which identifies the stationary process of the variables’ underlying processes. Second, the autoregressive distributed lag (ARDL) model was used to produce the variables’ short- and long-run estimates. Third, estimations of Granger causality examined the causal relationships between the variables. Finally, innovation accounting matrices (IAM)were utilized to predict the relationships between variables during the following decade. The unit root estimates imply the mix order of variable integration; hence, it is appropriate to employ ARDL modeling for parameter estimations. The ARDL estimations demonstrate that combustible renewables and waste decrease a nation’s carbon emissions by boosting industrial waste recycling. Despite recycling systems, carbon emissions have escalated to uncontrolled levels owing to the massive production of municipal solid garbage. Sustainable waste management and recycling are vital to reducing carbon emissions. Granger’s estimations of causation imply that combustible renewables and waste and carbon emissions cause industrial and municipal solid waste recycling. Additionally, population growth is responsible for greenhouse gas emissions, biowaste recycling, and industrial waste recycling. Furthermore, this shows the two-way connections between combustible renewables and waste and carbon emissions, implying the need to develop green waste recycling strategies in a nation. The IAM method identified future relationships between variables, which aids policymakers in implementing sustainable waste management practices for a nation. This study concludes that the environmental consequences of waste generation and recycling impede the nation’s circular economy agenda, which can be sustained by knowledge spillovers, chemical reduction in manufacturing, and allocating a certain amount of US dollars to ecological resource conservation. Full article

Increased fashion consumption spurred by fast fashion has led to excessive textile waste, giving rise to a global crisis as textile waste pollutes land and waterways, while landfill and incineration contribute to global greenhouse gas emissions. Extending a product’s life for as long as possible is a core principle of the circular economy (CE) to ensure that the maximum value of the original product is realized over its lifetime. As such, repair is an essential component of a CE because it supports the preferred waste hierarchy elements of reduce and reuse, with recycling being the last resort in a CE necessary to close resource loops. Consumers are an essential enabler of a CE; therefore, it is critical to understand consumers’ characteristics in the context of behaviors such as repair. The purpose of this study was to examine the role of gender on engagement in clothing repair practices; women have often only been the focus of clothing repair studies. An online survey was conducted to collect responses from Canadian and U.S. consumers (n = 512). Findings showed that self-repair was the most common form of clothing repair, with women being more highly engaged in self-repair practices, increasing with age. Paid repair is the type of repair that has the lowest level of engagement, and there are only negligible differences between the genders. Men utilize unpaid forms of repair more than women. However, among the youngest age group (18–24), both genders are equally likely to have clothing repaired for free. Gender gaps exist, but opportunities for increased utilization in repair can be created to encourage full participation within a CE. In particular, the findings point to the importance of increasing repair activities amongst men and younger consumers. Full article

Recycled aggregates (RAs) have been playing an important role in replacing natural aggregates (NAs) in concrete production, thereby contributing to a reduction in the extraction of natural resources and the promotion of a circular economy. However, it is important to assess the global impacts of this replacement, in both environmental and economic terms. In this study, an overview of the impacts of the production of natural and recycled aggregates is presented, using the life cycle assessment (LCA) methodology. Through this methodology, products with the same function are compared and information about the best solutions is given, considering their environmental and economic impacts. Studies with data collected from specific producers were compared, as well as environmental product declarations (EPDs) and generic databases, regarding the production of natural and recycled, coarse and fine, and rolled and crushed aggregates. This study intends therefore to provide the environmental and economic impact comparison at the global level through LCA from different data sources. According to this literature review, the best and worst environmental results are assigned to lower and higher transport distances, respectively. Regarding EPDs, the lowest environmental impacts are related to recycled coarse aggregates and the highest to natural coarse crushed aggregates. In terms of generic databases, the results are similar, with the lowest impacts associated with natural fine rolled aggregates and the highest to natural coarse crushed aggregates. In what concerns the economic impacts, in general, recycled aggregates are associated with the lowest costs. However, these results are highly dependent on transport distances and costs. Full article

Efficient packaging waste management systems are essential considering recent revisions of the European legislation on packaging waste management that sets ambitious targets. European rules aim to deal with the increasing quantities of packaging waste, which cause environmental problems. Consequently, it is necessary to identify functional packaging waste management systems to achieve these targets effectively and efficiently. However, given the heterogeneity of the different packaging management systems, policymakers, scholars, and industry operators struggle to have a comparative view. The number of non-harmonized laws in force across countries, autonomous recycling targets, and constant updates are prominent problems that make it difficult to obtain comparable information for research, business, and policymaking. To fill this gap, our research question consists of assigning responsibilities for prevention, collection, recycling, and recovery and an overview of some models at a glance with respect to the general governance and functioning of the system. We base our research on a multiple-case design since more cases are examined using complementary data collection methods, analysis of the previous literature, reports, legislation, and business and institutional websites. Our results provide insights from the following cases: Germany, France, the United Kingdom, the Netherlands, Portugal, Denmark, Spain, and Italy. In addition, policy implications emerge as our insights help overcome barriers in the European market’s development caused by the different rules on packaging management and design serving policymakers that aim to harmonize the management of packaging waste. The paper also contains managerial implications for circular economy business models that can be used by managers who aim to design or upgrade their business models according to both recent legislative upgrades and packaging management systems. Full article

Reinforced concrete based on ordinary Portland cement (OPC) is one of the most commonly used materials in modern buildings. Due to the global growth of the building industry, concrete components have been partially or completely replaced with waste materials that can be used as binders or aggregates. Besides the ecological aspects, modern architecture widely needs materials to make the concrete durable, resisting large loads and various detrimental forces in the environment. This opens the possibilities of managing waste materials and applying them in practice. This paper presents a concise review of the green solutions for ecofriendly materials in the building industry that deal with the practical application of materials commonly treated as waste. The main emphasis was placed on their influence on the properties of the building material, optimal composition of mixtures, and discussion of the advantages and disadvantages of each of the “green” additives. It turned out that some solutions are far from being ecofriendly materials, as they leech and release numerous harmful chemicals into the environment during their presence in concrete. Finally, the paper suggests a research direction for the development of an ecofriendly structural material for a sustainable future. Full article