High-quality Recycling Research Articles

Optimal design of a post-demolition autoclaved aerated concrete (AAC) recycling network using a capacitated, multi-period, and multi-stage warehouse location problem

Autoclaved aerated concrete is a popular building material in constructing one- and two-family houses because of its low thermal conductivity and fire resistance. Since autoclaved aerated concrete production rose significantly in the 1960s and 1970s, increasing post-demolition volumes can be expected in the following decades. However, these are currently landfilled as high-quality recycling options are still to be established.This study develops a new capacitated, multi-period, and multi-stage network model for optimising a Germany autoclaved aerated concrete recycling network. The multi-period character of the model enables the precise consideration of increasing post-demolition volumes by constantly allowing the move of recycling plants or opening new ones throughout the planning horizon. Additionally, the multi-stage formulation facilitates incorporating an optional second recycling step, which involves additional effort and higher revenues. The model aims to find a cost-minimised recycling network and identify optimal network transformations until 2050. Results show that recycling is preferred over landfilling. The optimised recycling network uses large recycling plants for economies of scale and opens new plants in the future to handle the expected increase in post-demolition autoclaved aerated concrete. Transport costs account for the largest share of total costs (50%), while fixed costs reach around 40%, and revenues offset approximately 20% of all costs. The total costs of the network reach about 2200 M€ until 2050, which is 4600 M€ (68%) less than without establishing recycling. The results offer new insights into cost-minimal network structures and their future development to encourage decision-makers to promote autoclaved aerated concrete recycling.

Enhancement of Sustainable Recycling Systems for Industrial Waste in South Korea via Hazardous Characteristics Analysis

The South Korean government has implemented an acceptance system to promote the high-quality recycling of waste. Industrial waste generators must provide “hazardous characteristics data” to recycling operators. Nonetheless, ~80% of industrial safety accidents in South Korea occur during recycling, most involving fire or explosions. Moreover, a gap in safety management exists during ‘Circular Resource’ acceptance if the target substance is not regarded as waste. In this study collected data on hazardous waste characteristics. From 62 waste generators, 72 waste samples were collected, accounting for most of the resources accepted for recycling, including waste synthetic polymers, slag, dust, waste sand, and waste foundry sand. Then, the hazardous characteristics, as stated in the Ministry of Environment notifications, were assessed. Leaching toxicity was detected in one slag sample and six dust samples. The Cd, Cu, As, Pb, Zn, Ni, Hg, F, and CN levels dissatisfied the Soil Contamination Warning Standard in 31 samples. Explosivity was not detected in any sample, whereas flammability was detected in one waste synthetic polymer sample. The results revealed 15 cases of potential flammability. Flammability is legally defined as below the criteria if the combustion speed criterion is not met. However, in the case of flame ignition, which could cause large fires and safety accidents, the relevant notification should be revised. In this study, we aimed to improve the gap between the hazardous waste management systems and industrial fields through actual measurements of hazardous characteristics. By doing so, we seek to contribute to the prevention of environmental and safety accidents. By continuously accumulating data and utilizing actual measurements, we aim to revise and enhance relevant regulations, ultimately improving the hazardous characteristics of waste management systems.

Consequential life cycle assessment of demolition waste management in Germany

ContextBulk mineral waste materials such as construction and demolition waste are Germany’s largest waste stream. Despite the availability of high-quality recycling pathways such as road base layers, waste concrete is predominantly recycled into lower-quality recycling pathways like earthworks or unbound road construction. This is due to low demand for recycled aggregates in road base layers and frost protection layers, especially in public procurement.PurposeThis study assesses the environmental consequences of increasing high-quality recycling of waste concrete in the near future to provide decision support for public procurement in Germany. The focus lies on climate change due to its importance for decision-makers. However, 17 other impact categories were assessed to avoid problem shifting.MethodsLife cycle assessment (LCA) is applied with background data from ecoinvent 3.9.1. Impact assessment was conducted at midpoint level using IPCC 2021 and ReCiPe Midpoint (H). Foreground data were taken from literature and expert interviews. In line with the goal of this LCA, a consequential modeling approach was followed to account for changes in the material flow system. Substitution creates a cascade effect previously omitted in consequential LCA studies, in which lower quality recycling materials replace higher quality recycling materials in their respective utilization pathways.Results and discussionIncreasing the high-quality recycling of waste concrete into road base layers causes a reduction in environmental impacts for all 18 impact categories, as it replaces natural aggregate and avoids backfilling of mixed mineral waste and excavated earth through substitution effects. Transport distances and ferrous metal recovery were identified as hot spots. Sensitivity analyses show that only transport is a significant issue.ConclusionIncreasing the high-quality recycling of waste concrete in Germany is recommended in terms of environmental impacts. Lower-quality recycling is environmentally feasible only in cases where the avoided transport distances for natural aggregates and backfilling are significantly lower than the additional transport distances for high-quality recycling.

Mechanochemical preparation and performance evaluations of bitumen-used waste polypropylene modifiers

The value-added recycling of waste polypropylene (PP) as asphalt modifiers has been a popular research topic in recent years, but high blending temperatures and asphalt smoke emissions are difficult issues that have not been solved. Therefore, this study innovatively used phthalic anhydride (PA) and catalysts (NHPI or BPO) to mechanochemically turn waste PP into different reaction products as bitumen-use PP modifiers (PPM(N) & PPM(B)). To well understand the physicochemical characteristics of PPMs, thermogravimetric analysis, torque rheology, and scanning electron microscopy were adopted and analyzed. Furthermore, the penetration, softening point, viscosity, storage stability, and dynamic shear rheology (DSR) tests were also carried out to study the performance differences of their PP modified asphalt (PPMA(N) & PPMA(B)). The main results showed that the PPM(N) continues being degraded with PA, but BPO-degraded PP conversely gets chemical connections with PA. With the effects of NHPI and BPO, all PPMs can improve the deformation resistance of virgin bitumen, even at higher temperatures, but as the PA content increases, this performance will gradually deteriorate for PPMA(N) and shows a slight improvement for PPMA(B). The appropriate use of PA can decrease the mixing temperature of PPM(N) with virgin bitumen and improve the storage stability of PPMA binders, and will not significantly sacrifice the resistances of its PPMA(N) to deformation, while with the addition of PA, the mixing temperatures of PPM(B) and virgin bitumen will not be decreased as expected and the resistances of PPMA(B) to deformation remain unchanged. Overall, the proposed mechanochemical method can work out to well address the high-quality recycling and reuse issue of waste PP for its large-scale application in asphalt pavement.

Enhancement of recycling system for large WEEE plastics in Korea via material flow analysis (MFA) and hazardous substances assessment

Globally, there is interest in recycling waste electrical and electronic equipment (WEEE) plastics for transition to circular resource society and concern about substances with potential harzard in WEEE. For high-quality recycling of WEEE plastics, it is necessary to find factors that hinder recycling of the entire life of plastics and investigate hazardous substances for recycling safety. In this study, through conducting material flow analysis(MFA), 27 kt of WEEE was collected and only 3.9 % of the production was returned to plastic recycling market. To resolve this gap, further research by related organizations, including updating statistical data on the plastics, is required in addition to consideration for converting unofficial routes into official routes. For the activation of the secondary material recycling market, strict quality control is required, because some samples contained relatively high levels of PBDEs DEHP restricted under law. And it is necessary to monitor of unrestricted substance, TBBPA and Bisphenol A detected at high concentration in WEEE plastic, for the safe recycling of plastic waste.

High-Quality Recycling and Utilization of China’s Steel Scrap Resources in the Context of Carbon Peaking and Carbon Neutrality

High-Quality Recycling and Utilization of China’s Steel Scrap Resources in the Context of Carbon Peaking and Carbon Neutrality

Incentive contract for high-quality recycling of construction waste: Considering fairness concerns and information asymmetry

Incentive contract for high-quality recycling of construction waste: Considering fairness concerns and information asymmetry

Design for circularity in manufacturing industries–operationalisation and decision support

Achieving a more circular economy can be an important contributor to sustainable development. The successful implementation at the industrial level requires the development of circular products, services and business models. This paper addresses the compelling need for industrial product development to consider the entire life cycle of products from raw material extraction to the end of life to initiate and evaluate circular economy improvements such as lifetime extension or high-quality recycling. The actual implementation of circular economy in industrial product design processes hasn't yet been extensively researched. This paper operationalises a comprehensive design for circularity by conceptualising a decision support method for the industrial product development process based on literature analysis, decision matrix methodology, and expert evaluation. Results highlight the interplay of circular business models, ecodesign approaches, and product life cycle intensities and shape the basis for technical circular design principles and metrics as well as advanced implementation-oriented research in the field.

Rigid Polyethylene Terephthalate Packaging Waste: An Investigation of Waste Composition and Its Recycling Potential in Austria

The need for increased recycling of plastic packaging waste (PPW) is apparent from a legal and waste management perspective and, therefore, further waste streams need to be investigated in detail in terms of their recycling potential. Polyethylene terephthalate (PET) PW is already closed-loop recyclable (bottle-to-bottle recycling); however, other rigid PET PW is mainly thermally recovered. Explicit quantitative and qualitative data on rigid PET packaging waste are limited. Therefore, this study investigates the composition and packaging characteristics of rigid PET packaging waste contained in separate waste collection as well as in the mixed PET sorting stream in Austria by conducting a manual sorting analysis. Furthermore, the waste volume is projected, and the recycling potential is extrapolated according to new European recycling rate reporting formats. The results show that approximately 11% of separate collection represents rigid PET packaging waste. Most PW derives from food packaging and is transparent. Contained residues with more than 1% of the total packaging weight might negatively impact the sortability. The applicable net quantity indicator (ALR) amounts to 0.888 at the stage of sorting. The volume of rigid PET PW is extrapolated to 26–36 kt in 2020 with a high-quality recycling rate of 25%, which contributes 2.6% to the Austrian PPW recycling target of 50%.

The circular economy potential of reversible bonding in smartphones

The increased use of adhesive bonding in manufacturing is an important barrier to implement circular economy strategies, including repair, refurbishment, and high-quality recycling. The circular economy potential of reversible adhesives that are debondable on demand, however, remains largely unexplored. In this paper we apply an integrated technology-agnostic framework to smartphones to identify and quantify the circular economy potential of reversible bonding. In this framework we combine insights from Life Cycle Assessment, Life Cycle Costing, and Statistical Entropy Analysis. We find that reversible bonding of smartphones can be an enabler for circular strategies and have a considerable positive impact on preserving higher functionality on a product, component, and material level. The major added value of reversible bonding is its potential to replace and update parts, retaining the main environmental hotspot of a smartphone. Firms, however, will not likely switch to this technology, even though bonding and debonding make up only a small fraction of total lifecycle costs. Therefore, policy recommendations include mandatory policies on repairability and public procurement favouring the use of reversible bonding techniques. This would alter incentives in contexts where consumer preferences for lease markets cannot be taken for granted. The evaluation of different debonding scenarios from three distinct perspectives provides a comprehensive, more reliable, and robust understanding of the trade-offs related to debonding and its potential contribution to the circular economy.

High-quality electrostatic recycling of waste carbon fiber via spark-driven shock waves and Joule heating

The recycling of waste carbon fibers (CF) has emerged as a crucial research area for both environmental protection and economic sustainability. To sufficiently exert the potential and extend the application life cycle of CFs, here we propose an eco-friendly and efficient electrostatic method for rapid recycling of tightly entangled reclaimed carbon fibers (rCFs) by spark-driven disentanglement and depolymerization. Our research indicates that the spark discharge generated by fiber induction under low-voltage conditions can excite the shock waves and Joule heating effects, resulting in the separation of individual rCFs and the removal of surface organic matrix. Furthermore, the constructed electric field can synchronously and continuously orient the dispersed rCFs to form a vertical alignment in a short time with good maneuverability and directionality for reutilization. The results demonstrate that this one-step disentanglement, depolymerization, and alignment method achieves a high-quality recycling process with 100% dispersion efficiency, minimal damage, cost-effectiveness, uniform distribution, upright orientation, and high-speed embedding performance. Our findings reveal the potential of the electrostatic strategy for the high-quality recycling of rCFs, in line with the principles of the circular economy. The proposed method offers broad prospects for application in continuous in-line production and material manufacturing, and is a step towards sustainable and cost-effective CF recycling.

Modelling the Barriers to Circular Economy Practices in the Indian State of Tamil Nadu in Managing E-Wastes to Achieve Green Environment

Owing to a heightened necessity, the consumption rate of electronic items has increased exponentially in recent decades, resulting in huge quantities of electronic waste (e-waste). Though increasing e-waste has many adverse impacts, it also provides an ample opportunity of recover value from the waste through circular economy (CE) practices. However, the adoption to CE practices is jeopardised by myriad barriers. This paper wishes to identify and evaluate the barriers that hamper CE practices in e-waste management. First, 30 barriers to the adoption of CE practices in India e-waste management are identified by reviewing the existing literature and conformed using experts’ inputs. Furthermore, based on the experts’ opinion, the thirty barriers are categorised into social, economic, and environmental categories. An integrated multi-criteria decision-making (MCDM) framework of fuzzy decision-making trial and evaluation laboratories (FDEMATEL) and fuzzy analytic network processes (FANP) is employed to understand the causal interrelationship and also to rank the barriers. Uncertainty about the profitability of the circular economy (E9), insufficient market demand (E6), lack of successful circular business model (E5), shortage of high-quality recycling materials (E4), and lack of adequate technology (EN6) have been identified as the top five barriers to the incorporation of CE practice in e-waste management. Out of these 30 barriers, 12 come under the cause group and 18 come under the effect group. Understanding the causal interrelationship and prioritization of barriers provide better insight into the barriers. This study offers some managerial implications that could assist industrial practitioners and policymakers.

Analysing the potential of the selective dissolution of elastane from mixed fiber textile waste

Textile products are composed of various blends of synthetic or natural polymers. Elastane increases the functionality during use phase, but impedes high quality recycling. This study investigates the selective chemical dissolution of elastane from blended textile. Hansen solubility parameters and COSMO-RS were applied for solvent screening. The most recommended biobased solvents were experimentally validated with polyester, polyamide, cotton, wool and elastane for which solubility limits were determined and hence, their selectivity towards elastane dissolution. A TGA-corrected gravimetric method was developed as quantification tool and showed that tetrahydrofurfuryl alcohol and ɣ-valerolactone have comparable elastane dissolution capabilities to classical solvents (5 mg elastane/g solvent). Polyester/elastane and polyamide/elastane blends were subjected to this process as case studies. The LCA study showed that this selective solvent-based dissolution process saves 60% CO2-eq./kg textile waste compared to incineration. This interdisciplinary work can set the benchmark for further developing and upscaling physical/dissolution recycling processes for blended textiles.

Chemical upcycling of waste PET into sustainable asphalt pavement containing recycled concrete aggregates: Insight into moisture-induced damage

Waste polyethylene terephthalate (PET) plastic and construction and demolition waste are main municipal solid wastes. If they are not properly disposed of, they will cause continuous damage to the ecological environment. Previous studies have shown that recycled concrete aggregate (RCA) can be successfully adopted to replace natural aggregate (NA) for asphalt pavement construction. However, the moisture-induced damage, as one of the pavement engineering performances, is very prominent for asphalt concrete containing RCA (RCA-AC), due to the high absorption of RCA and the weakness of the adhered mortar. Given this, PET additive, derived from waste bottle bodies, is considered to improve the resistance of RCA-AC to moisture-induced damage in this study, which has been previously identified effective to enhance the anti-stripping characteristics of asphalt mixtures containing NA. To achieve this goal, this study applied a series of tests including contact angle, image recognition, boiling water test, immersed Marshall test, freeze–thaw (F-T) splitting test, wheel tracking test, and field emission scanning electron microscope (FESEM) to evaluate the moisture-induced damage of RCA-AC containing PET additive. The results showed that PET additive has a significant ability to improve the bonding strength and adhesion of asphalt binder to RCA and reduce the stripping percentage and moisture-induced susceptibility of RCA-AC, especially under the F-T cycles. In addition, the 60 °C rut deformation resistance of RCA-AC after immersion can be improved as the PET additive is used. Furthermore, the interfacial bonding layers (IBL) of PET additive modified asphalt binder between RCA particles are still existent and its width is not significantly increased after immersion and F-T cycles by contrast to that of virgin binder. In general, the appropriate use of PET additive is a good approach to promote the high-quality recycling of RCA into sustainable asphalt pavement.

Metallic product recognition with dual attention and multi-branch residual blocks-based convolutional neural networks

Visual recognition technologies based on deep learning have been gradually playing an important role in various resource recovery fields. However, in the field of metal resource recycling, there is still a lack of intelligent and accurate recognition of metallic products, which seriously hinders the operation of the metal resource recycling industry chain. In this article, a convolutional neural network with dual attention mechanism and multi-branch residual blocks is proposed to realize the recognition of metallic products with a high accuracy. First, a channel-spatial dual attention mechanism is introduced to enhance the model sensitivity on key features. The model can focus on key features even when extracting features of metallic products with too much confusing information. Second, a deep convolutional network with multi-branch residual blocks as the backbone while embedding a dual-attention mechanism module is designed to satisfy deeper and more effective feature extraction for metallic products with complex characteristic features. To evaluate the proposed model, a waste electrical and electronic equipment (WEEE) dataset containing 9266 images in 18 categories and a waste household metal appliance (WHMA) dataset containing 11,757 images in 23 categories are built. The experimental results show that the accuracy reaches 94.31% and 95.88% in WEEE and WHMA, respectively, achieving high accuracy and high quality recycling.

ECONOMIC ASPECTS AND LEGAL REGULATIONS OF RECYCLING IN THE REPUBLIC OF SERBIA

The topic of waste management and recycling is becoming very important both in our country andthroughout the world. The goal is to emphasize the importance of the environment, its protection and thepreservation of the world around us. Recycling is a key component of modern waste reduction. It promotesenvironmental sustainability by removing input raw materials and redirecting waste production into the economicsystem. The question of environmental protection is a question of the future. It is not possible to protect theenvironment if we do not prevent the accumulation of various wastes, the sanctioning of which is constantlypostponed. Urbanization and globalization bring increasing needs of each individual for packaged goods, whichleads to a huge increase in packaging worldwide. The development of industry leads to increased industrial waste.The only way to control waste is recycling treatment. By recycling, in addition to the reduction of waste disposed ofin landfills, we enable re-production, i.e. the use of waste for the re-production of a product. The recycling processhas a huge ecological and economic importance in the system of a country. For a recycling program to work, a large,stable supply of recyclable materials is essential. High-quality recycling can support economic growth bymaximizing the value of waste materials. Three legal options have been used to create such stockpiles: compulsorycollection of recycling, a law on depositing containers and a ban on waste. Compulsory collection laws set recyclingtargets for cities, so a percentage of the material must be diverted from the city's waste stream by a target date. Thecity is responsible for working towards this goal. Recyclable quality not only supports high-quality recycling but canalso bring significant environmental benefits by reducing, reusing and keeping products out of landfills. Anytreatment that is planned to be used in the recycling process must be justified by legal regulations. The keyinstitutional responsibility in the field of waste management lies with the Ministry of Environmental Protection ofthe Republic of Serbia, which, in accordance with the Law on Ministries, performs state administration tasks relatedto: waste management, including hazardous waste, except for radioactive waste; approval of cross-border transportof waste, as well as other tasks specified by law. The paper presents the principle of municipal waste management inthe Republic of Serbia. By reviewing data from abroad, the goals that the Republic of Serbia strives to achieve inthis matter are analyzed, as well as the legal frameworks that regulate the achievement of those goals. The analysisincludes the recycling process itself, its flows, as well as waste management treatments. Concrete ecological andeconomic aspects of recycling that affect life and work in the Republic of Serbia are presented.

An Approach for Automated Disassembly of Lithium-Ion Battery Packs and High-Quality Recycling Using Computer Vision, Labeling, and Material Characterization

A large number of battery pack returns from electric vehicles (EV) is expected for the next years, which requires economically efficient disassembly capacities. This cannot be met through purely manual processing and, therefore, needs to be automated. The variance of different battery pack designs in terms of (non-) solvable fitting technology and superstructures complicate this. In order to realize an automated disassembly, a computer vision pipeline is proposed. The approach of instance segmentation and point cloud registration is applied and validated within a demonstrator grasping busbars from the battery pack. To improve the sorting of the battery pack components to achieve high-quality recycling after the disassembly, a labeling system containing the relevant data (e.g., cathode chemistry) about the battery pack is proposed. In addition, the use of sensor-based sorting technologies for peripheral components of the battery pack is evaluated. For this purpose, components such as battery pack and module housings of multiple manufacturers were investigated for their variation in material composition. At the current stage, these components are usually produced as composites, so that, for a high-quality recycling, a pre-treatment may be necessary.

Plastics Flow Analysis for Korea, 2017-2019

As one of the world''s top producers and top consumers of plastics, Korea has been experiencing problems with regard to the management of waste plastics since 2018, such as collection service disruptions, illegal abandonment and exports of waste, and marine pollution. To gain a complete understanding of Korea''s contemporary management of plastics, this study quantified national plastic flows across production, use, and end-of-life management between 2017 and 2019. In 2017, Korea produced 17.5 million metric tons of plastic resins, more than half of which was exported, and consumed 7 million metric tons of plastic products including 3.2 million metric tons of packaging. On a per-capita basis, Korea''s plastic consumption and waste generation were higher than that of other major economies, such as Japan, China, the United States, and Europe, which implies considerable potential for plastic consumption reduction. Despite the high level of waste generation, Korea has increased the level of material recycling while minimizing the landfill rate by implementing various policies, such as waste levies, voluntary agreements, and extended producer responsibility. For more sustainable plastic management, Korea must make additional efforts to reduce plastic consumption and promote high-quality recycling, for example through circular design, business models with less packaging, and advanced technologies.

Development of a System for Recycling Used Batteries and Lead-Containing Batteries: Assessment of the Economic Effect with Minimising Damage to the Environment

The relevance of the subject under study is determined by the issues of practical application of charging batteries and accumulators after the completion of the declared technical lifetime, in connection with the pollution problems due to lack of potential for normal disposal. The purpose of this study is to investigate the prospects of development and practical implementation of a system of recycling used batteries and lead-containing batteries, in the context of assessing the potential economic impact of minimising environmental damage while fully implementing the objective. The methodological framework of this study comprises a combination of quantitative and qualitative methods. The application of methods of analysis, synthesis, induction, and deduction in this paper provides sufficient information about the existing principles of recovery of lead-containing batteries and accumulators. The method of generalisation involves the implementation of a qualitative assessment of the data obtained in this study. The method of modelling provides the display of the results obtained using appropriate schemes and diagrams. The available publications of several researchers engaged in scientific development of the issues of disposal of spent lead batteries and accumulators were analysed. The factors of the economic effect that can be achieved by the high-quality recycling of lead-containing batteries were investigated. An approximate assessment of the economic effect with a given direction to minimise damage to the environment was formed. The results obtained in this paper and the conclusions formulated on their basis have practical significance in terms of the prospects of increasing the volume of production of secondary lead by recycling of used batteries and reducing damage to the environment, when it is uncontrollably contaminated by secondary products of their use

Modelling and Simulation of Building Material Flows: Assessing the Potential for Concrete Recycling in the German Construction Sector

The reuse and recycling of materials can make an important contribution to the conservation of natural resources in the sense of a circular economy. This applies in particular to high quality recycling, supporting the material use of waste and closing product cycles. The construction sector is the most important sector in terms of available volume of materials for recycling. However, the largest share of recycling (RC) materials goes predominantly into road construction and underground engineering. This research developed a dynamic model and used a simulation tool to calculate future building material flows in the German construction sector of residential buildings to explore the medium- and long-term potential for RC concrete. The results show that, by increasing the RC rate of concrete to produce recycled aggregates for concrete (RAC) from currently 1.5% to 48%, up to 179 million tons of sand and gravel could be saved until 2060. If the current maximum secondary input rate of RAC of 45% is increased to 70%, the savings could rise over another 66 million tons. If a secondary input rate of 100% is applied, RAC could completely fulfill the demand for sand and gravel for new residential building in Germany from 2045 onwards. The approval of RC concrete for more concrete strength and exposure classes is required to avoid a surplus of RAC and a rapid exhaustion of landfill capacities in the future.