Direct Reuse Research Articles

Exploring take-back recovery strategies in the Circular Economy

The take-back of end-of-use products has gained increasing importance with the growing focus on the circular economy. However, not all take-back strategies have been thoroughly explored and understood in relation to consumer engagement. This study examines the role of take-back recovery approaches and strategies in the circular economy, integrating a product design and service lens to address consumer return practices. The research identifies four distinct opportunities under the take-back umbrella: Direct Reuse, Ease of Disassembly, Final Recovery, and Safe Disposal. For each opportunity, potential sub-opportunities are identified and expanded upon. Through a multiple case study analysis, these sub-opportunities are further developed using a "Design for X" approach to form nine distinct take-back strategies. This research emphasizes that the appropriateness of a take-back strategy depends on various factors, such as consumer behavior and context, industry specifics, and material flows. The study highlights the critical role of take-back systems and returns behavior in promoting circular product development and consumption.

Direct Reuse of Spent Nd–Fe–B Permanent Magnets

Nd–Fe–B permanent magnets are vital for numerous key technologies in strategic sectors such as renewable energy production, e-mobility, defense, and aerospace. Accordingly, the demand for rare earth elements (REEs) enormously increases in parallel to a significant uncertainty in their supply. Thus, research and innovative studies are focus on the investigation of sustainable solutions to the problem and a closed-loop value chain. The present study is based on two benign-by-design approaches aimed at decreasing the recycling loop span by preparing standardized batches of EoL Nd–Fe–B materials to be treated separately depending on their properties, as well as using mechanochemical method for waste processing. The previously reported benefits of both direct recycling and mechanochemistry include significant improvements in processing metrics, such as energy use, ecological impact, technology simplification, and cost reduction. Waste-sintered Nd–Fe–B magnets from motorbikes were collected, precisely sorted, selected, and pre-treated. The study presents a protocol of resource-efficient recycling through mechanochemical processing of non-oxidized sintered EoL magnets, involving the extraction of Nd2Fe14B magnetic grains and refining the material’s microstructure and particle size after 120 min of high-energy ball milling in a zirconia reactor. The recycled material preserves the main Nd2Fe14B magnetic phase, while an anisotropic particle shape and formation of a thin Nd/REE-rich layer on the grain surface were achieved.

An investigation of the engineering properties and environmental impact of low-temperature modified electrolytic manganese residue for karst grouting materials.

An investigation of the engineering properties and environmental impact of low-temperature modified electrolytic manganese residue for karst grouting materials.

Direct reuse of the end‐of‐use structural steel: Assessing the economic and carbon reduction effects

Abstract Due to increasing market demand and limited resources for utilization and allocation, the global economy faces mounting pressure. Construction and demolition waste (C&DW) is therefore considered a potentially significant source of secondary materials for the future. To prolong the service time of these end‐of‐use products within the construction sector, innovative business models for effectively utilizing these urban mines are emerging, with direct reuse strategies being one practical solution. Among various types of C&DW, the inherent properties of steel make it particularly favorable for direct reuse. This study develops a hybrid input–output analysis and environmental extended input–output analysis model to assess the economic and environmental impact of applying a direct reuse strategy in the construction sector, with a focus on end‐of‐use structural steel products from end‐of‐service buildings. Under the scenario that end‐of‐use structural steel is directly reused, the economy may experience slight output value losses owing to reduced demand for raw material and remanufacturing sectors. However, it can result in significant carbon reduction impacts on energy and raw material sectors. Moreover, the carbon reduction achieved through the direct reuse strategy is around 25% of that achieved by transitioning from blast furnace‐basic oxygen furnace (BF‐BOF) steelmaking process to direct reduced iron‐electric arc furnace (DRI‐EAF) steelmaking process. These findings indicate that the innovative direct reuse business strategy could effectively serve as a catalyst for reducing carbon emissions across the entire economy.

Combinatorial optimization approach for the efficient reuse of RC components

Abstract The reuse of reinforced concrete (RC) components from deconstructed buildings offers a promising approach to reduce the environmental impact of new constructions. However, it represents a complex combinatorial optimization problem to efficiently place the available modules, which vary in geometry and load‐bearing capacity, into new structures while maximizing their utilization. This paper proposes a two‐stage optimization method to enable the reuse of arbitrary RC modules. First, an agent‐based model is employed to rapidly explore feasible geometric combinations of modules and preselect suitable placements based on a target span length. Second, metaheuristic optimization algorithms, namely Simulated Annealing and Tabu Search, are adapted to maximize the utilization of the modules' load‐bearing capacity while ensuring global structural integrity. The methods are demonstrated on a case study of assembling a three‐span continuous beam. Lacking real data of dismantled RC elements, a construction kit of 100 modules with varying cross‐sectional properties and material parameters is artificially sampled. The results show the agent‐based preselection effectively finds viable geometric combinations, while the metaheuristics converge on optimized module placements with up to 88% utilization on average. The proposed approach provides a computational framework to enable the direct reuse of structural concrete components, supporting the design of low‐carbon circular buildings.

Rethinking replacement, rebound and environmental impact in reuse practice

Despite the current emphasis on reuse as a primary strategy for realising more circular economic systems, researchers have questioned the assumed environmental benefits of the practice – arguing that reuse can result in unintended rebound effects that diminish or outweigh environmental gains. This article reviews studies focused on potential rebound effects in reuse practices – not as a means to re-adjudicate the environmental virtues of reuse – but rather to critically examine common assumptions about the people and practices that animate reuse markets. The article thus responds to calls for additional research on the behavioural dimensions of reuse in more circular economic systems – and the associated implications for modelling environmental impact. We draw on an in-depth study of 30 active participants in direct product reuse markets to theorise everyday circularity from a critical social science perspective. We argue, based on our observations, that environmental impact models of reuse should not assume that: (1) all forms of product reuse are the same; (2) buyers and sellers are driven primarily by price logics; and (3) new goods are the default preference. We find reuse markets to be much more fluid than imagined by environmental impact models and argue that these insights are particularly important to consider as we approach the end of cheap nature and the costs of overconsumption are increasingly clear.

Water reuse options for decentralised MBR effluents: a case study in South Africa

ABSTRACT Treated wastewater is emerging as a promising alternative water solution. This study evaluated the feasibility of reusing effluents from three decentralised membrane bioreactor (MBR) wastewater treatment facilities in Western Cape, South Africa. Using water quality results from each facility, the technical feasibility of irrigation and both indirect potable and direct potable reuse (DPR) options for MBR effluents was evaluated. Effluents from all facilities typically meet national irrigation standards, with only one site requiring pH correction. Partially recharged groundwater with 25% of its water demand using MBR effluents requires additional treatment for organic matter, faecal coliform, nitrates, colour, saturation index, iron, and manganese parameters to meet drinking water quality upon abstraction. For DPR, MBR effluent must undergo pre-treatment to remove excess organic matter, turbidity, and suspended solids before advanced treatment with reverse osmosis. However, only one facility has economic feasibility for potable reuse with payback periods of 7 and 8 years for DPR and indirect potable reuse, respectively. Potable reuse may not be economical for small-scale MBR plants unless the necessity for drinking water reuse outweighs the financial implications. The study highlights the need for evaluating alternative low-cost technologies for MBR effluent treatment and integrated managed aquifer recharge modelling to assess various groundwater recharge scenarios.

Nanoconfined Polycarbene@Covalent Organic Frameworks for Efficient Gold Trapping from Electronic Waste

Abstract Gold, often recognized as a luxury jewelry, plays an important role in diverse fields because of its specific physical and chemical properties. However, the limited supply and lack of abundance of gold led to continuous competition for its use. Therefore, industries have developed various techniques for gold mining and recycling, e.g., gold recovery from electronic waste (e‐waste, commonly referred to as the gold bonanza). To address this challenge, a novel poly(ionic liquid)@covalent organic framework (PIL@COF) nanotrap for highly efficient gold recovery from e‐waste is reported. The orderly arrangement of PIL facilitated by COF nanochannels, coupled with the strong binding affinity of PIL to gold (generated by its polycarbene intermediate) and the highly ordered porous COF architecture results in the rapid and selective capture of gold ions. This polycarbene@COF material achieves a gold adsorption capacity of up to 1.9 g g−1 and exhibits excellent sorption kinetics of 90% gold adsorption within 10 min while simultaneously reducing Au3⁺ to metallic Au0, which enables direct gold recovery and reuse. The high selectivity and efficiency of the gold recovery of this composite material are further confirmed by theoretical calculations. In addition, this polycarbene@COF nanotrap demonstrates high effectiveness across a wide pH range and maintains stability over multiple adsorption‒desorption cycles, highlighting its potential as a sustainable and robust platform for the recovery of precious metals.

Some aspects of the compaction of raw dredged sediments for a direct reuse as fill material

The management of sediments dredged and deposited on land has been the focus of many recycling studies, especially in laboratories where small quantities of sediments are oven-dried. These investigations have usually concluded that recovery as a material requires stabilization/solidification treatment. Few research studies are available for the sustainable, ecological and direct use of dewatered sediments, particularly on the compaction of raw sediments and the analysis of the different influences related to their texture, composition and drying methods. The present study investigates the compaction of raw dredged sediments for their potential reuse as fill material in the infrastructure projects. A series of 16 types of sediment from various environments, including rivers, dams and harbors, were compacted at an energy equivalent to that of the normal Proctor test. The test used a miniature laboratory version of the conventional Proctor test to estimate optimal compaction parameters. The results show that factors such as particle size, plasticity, specific gravity and organic matter content have a significant influence on optimum compaction values. Four distinct groups of sediments were identified, each with specific characteristics in terms of maximum dry density and optimum moisture content. The analysis first focused on the study of the influence of these factors (geotechnical properties) on the optimum compaction parameters in relation with organic matter content, for which a threshold of 5% made it possible to distinguish between non-organic and organic sediments. Another important result concerns the sediment drying method, which affects an influence on these optimum compaction parameters. While the most common method used in laboratory studies is oven-drying, on-site applications use natural drying using ambient air. The trends observed for these drying methods could be useful to sediment authorities in the case of on-site applications.

Mild chemical recycling of waste wind turbine blade for direct reuse in production of thermoplastic composites with enhanced performance

Mild chemical recycling of waste wind turbine blade for direct reuse in production of thermoplastic composites with enhanced performance

Assessing the Feasibility of Integrating a Thermal Separational Method with PV Recycling Technologies

The growing volume of end-of-life photovoltaic (PV) panels, projected to reach 60–78 million tons by 2050, poses significant environmental challenges. With landfilling being the most cost-effective but unsustainable disposal method, developing eco-friendly processes to recover valuable materials is essential. One potential solution for recovering raw materials from PV panels is thermal treatment. Therefore, in this study, PV modules were heat-treated at a low heating rate, and their components were manually separated with an average efficiency of 90%. The recovered silicon wafers and tempered glass sheets were utilized to fabricate new PV panels using lamination technology. The applied heating parameters enabled the cells to be removed from the PV panels without structural damage. However, the results of electroluminescence tests showed that thermal treatment significantly damages the p-n junctions, rendering direct reuse in new panels unfeasible. The thermal separation methods outlined in this study offer valuable opportunities for industries employing various PV-panel-recycling technologies. These methods lay the groundwork for environmentally responsible management and recovery of materials from end-of-life solar panels, advancing sustainable recycling practices.

Water Reuse—Retrospective Study on Sustainable Future Prospects

In recent decades, societies and economies across the globe have started to show signs of stress associated with water shortages. Meeting the sustainability benchmarks in arid and semi-arid regions has caused water reuse to be considered a viable alternate source to augment the existing water supply resources. Water reuse, resource recovery, and recycling are extensions of the concept of a circular economy that has been practiced in other fields. Globally, the U.S. has played a leadership role in the development of guidance and regulations for various water reuse applications. Other countries and organizations have also developed similar programs. This paper aims to propose a review of the existing literature and provide a broader perspective of water reuse focusing on the most pressing issues such as direct potable reuse with the backdrop of viral pathogens and perfluorinated compounds. The global history of statutory developments to regulate the selected contaminants has also been discussed by covering the recent advancement in water reuse applications. Technological developments and regulatory trends are chronicled in the context of emerging contaminants linked with an imminent social, industrial, and agricultural prospectus. The proposed high viral log removal credit for water reuse is a challenging task especially at regular intervals; therefore, the treatment requirements must be verified to ensure public safety. The extreme persistence of PFAS, their tendency for buildup in biotic systems, and their removal is another challenging task which requires development of cost effective and efficient technologies. Disparity in the financial and technological capabilities of regional or internal stakeholders of shared watershed or aquifer is a bottleneck in tangible advancements in this area. The role of public–private partnerships in addressing the impending water sustainability challenges is discussed as a model for future direction in funding, managing, and public acceptance.

Direct water reuse: a hydraulic economic analysis of connecting the wastewater treatment effluent to water treatment influent

ABSTRACT Climate change is causing increased flooding and droughts. Droughts can cause drinking water sources to run dry. Therefore, recycling water from the wastewater plant effluent to the water treatment plant influent, also called ‘direct reuse’ is becoming necessary. A connection between a city's wastewater treatment plant (WWTP) effluent and water treatment plant (WTP) influent via pipe was simulated to provide an understanding of the capital costs and feasibility of execution. Hydraulic pipe-flow and pump equations were used to calculate the pipe and pump sizes needed for various flow rate and elevation head values. Various flow rate recycle rates were modeled by taking the WWTP effluent flow and in percentages ranging from 5 to 100% to estimate the pipe and pump requirements to send that amount to the WTP influent, including greenhouse gas emissions from pumping. The costs of installation were then determined using current market values for parts and trenching. Data analysis showed that the cost of this project is driven by the pump size requirements.

Mathematical insights into disassembly and separation of highly stressed CFRP structures

In the current effort towards sustainability, the aviation industry faces challenges in repurposing carbon fibre-reinforced plastic (CFRP) components effectively. Traditional “downcycling” methods fail to maintain CFRP integrity, as they involve cutting load-bearing fibres and re-embedding them with new polymers, which leads to fragmentation and loss of properties. Innovative solutions like non-destructive disassembly or dismantling offer precise separation without compromising fibre integrity. This method allows for the direct reuse of materials in similar or new applications and highlights the importance of advanced recycling technologies for fibre-reinforced plastics. In this work, an approach for disassembly based on the mechanism of wedge separation is developed. For this purpose, the mathematical fundamentals are first derived analytically and their applicability is demonstrated. Subsequently, the non-destructive disassembly of a stringer-stiffened CFRP structure is demonstrated using a Finite Element model in combination with a Cohesive Zone Approach. In summary, the wedge separation approach proves to be suitable for application in the non-destructive disassembly of stiffening elements, offering a promising method for future non-destructive disassembly within the scope of sustainable recycling.

Recovery of Neodymium from Spent Hard Disk Drivers by Microwave Treatment and Magnesium Liquid Extraction

Rare earth elements (REEs) possess unique physical and chemical properties that render them indispensable in various industries, including electronics, energy production and storage, hybrid and electric vehicles, metallurgy, and petro-chemical processing. The criticality of REE underscores the need to enhance the efficiency of primary resource extraction and promote circularity through increased recycling from secondary sources. This paper provides a brief overview of REE recovery from secondary sources, particularly waste from electronic and electric equipment (WEEE). The discussion encompasses direct reuse of magnets, short-loop recycling (direct recycling), hydro- and pyrometallurgical processes, highlighting microwave (MW) technology. Original results are presented, focusing on the recovery of neodymium (Nd) from permanent magnet scraps from hard disk drives (HDD-PC) using microwave-assisted liquid metal extraction (LME) with magnesium (Mg) as the extractant. The subsequent separation of Nd from the Mg-Nd alloy via vacuum Mg distillation that is reused in the process is described. The experimental study demonstrates that the LME process, conducted in a microwave furnace, is a viable method for recovering Nd from permanent magnet scraps, which are essential for reducing the environmental impact of REE extraction and promoting a circular economy. By separating Nd from the alloy through vacuum distillation (450–550 mmHg), at temperatures of 850–900 °C for 8 h, a Nd sponge with a content of 95–98 wt.% Nd was obtained. The extracted content of Nd in the Mg alloy increases with increasing temperature and holding time. It was found that ≈ 97% of the Nd in the scrap was extracted from 2 to 5 mm crushed scrap at 800 °C for 8 h, using a LiF-LiCl-MgF2 protecting flux in a furnace Ar atmosphere.

Membrane Treatment to Improve Water Recycling in an Italian Textile District.

The textile district of Prato (Italy) has developed a wastewater recycling system of considerable scale. The reclaimed wastewater is characterized by high levels of hardness (32 °F on average), which precludes its direct reuse in numerous wet textile processes (e.g., textile dyeing). Consequently, these companies utilize ion exchange resins for water softening. However, the regeneration of the resins results in an increased concentration of chlorides in the reclaimed wastewater that exceeds the limit set by Italian regulations for the reuse of water for irrigation purposes. The objective of this study is to investigate the potential of membrane filtration as an alternative method for removing hardness from water. Therefore, an industrial-scale ultrafiltration-nanofiltration (UF-NF) pilot plant was installed to test the rejection of hardness from the reclaimed wastewater. The experiment employed two types of NF membranes and three permeate fluxes (27, 35, and 38 L·m-2·h-1) for testing. The results demonstrated that the system could remove hardness with efficiencies exceeding 98% under all conditions tested. The experimental findings indicate that the UF-NF system has the potential to be employed as a post-treatment step to render the reclaimed wastewater suitable for all textile finishing processes and to expand the scope for reuse.

A Cost–Benefit Model for Sustainable Product Reuse and Repurposing in Circular Remanufacturing

This study developed and validated cost–benefit models to evaluate the economic feasibility of reuse and repurposing strategies in remanufacturing, utilizing activity-based costing to assess key financial factors and implications. The models provide a structured approach to compare reuse, repurposing, and recycling, focusing on identifying conditions that maximize cost savings and reduce environmental impact. Reuse strategies emphasize scenarios requiring minimal maintenance to extend product life, while repurposing explores transformations for new applications when direct reuse is not feasible. By quantifying reuse and repurposing costs, the models help manufacturers identify sustainable lifecycle extensions that support circular economy principles. The results demonstrate that reuse and repurposing are particularly advantageous when products retain significant remaining useful life. These models serve as practical tools for industries aiming to implement resource-efficient practices that enhance both economic resilience and environmental sustainability. Furthermore, these models can be adapted for specific industrial applications and enhanced with real-world validation, providing companies with actionable insights to further refine cost-saving and environmental impact predictions. This study addresses gaps in the current literature by presenting tailored cost assessment tools for circular remanufacturing, promoting informed decision making for sustainable manufacturing.

Reuse of End-of-life Seawater Reverse Osmosis (RO) Membranes for Water Treatment

Due to the continuing growth in RO desalination plants and the finite lifespan of the RO membranes, large stocks of the end-of-life (EoL) RO membranes are discarded to landfills. This has become a critical challenge in the RO desalination industry. The overall objective of this study was to validate the possibility of direct reuse of the end-of-life seawater reverse osmosis membranes (EoL SWRO) for brackish water desalination in order to limit the environmental impact of their disposal. This study investigates the membrane performance and characterization of four SWRO modules (EoL-M1, EoL-M2, EoL-M3, and EoL-M4). The hydraulic performance of the old membranes was assessed using 5,000 ppm synthetic (NaCl) brackish water and real brackish water, and was compared with the performance of two commercial membranes, namely brackish water RO membrane (BW30) and nanofiltration membrane (NF90). 84-92% NaCl rejection was achieved by direct reuse of EoL membranes, which was higher than the rejection characteristics obtained using commercial BW30 and NF90 membranes. Removal of common salts represent in natural water sources (Na2SO4, Mg2SO4 and MgCl2) and humic substances was also investigated using EoL membranes. The rejection of Na2SO4, MgSO4 and MgCl2 salt solutions was in the range of (50.0-85.8%) with a highest rejection value was obtained for Na2SO4 and the lowest rejection was observed for MgCl2 solution, while a complete rejection was achieved for humic acid. Salt rejection of real brackish water filtration by the EoL membranes (75-77%) presented NF-like properties (Salt rejection was obtained for NF90 membrane was 77%). Therefore, the potential of reusing EoL SWRO is promising and thus benefit the desalination industry and the environment in Oman.

Magnetic Performance and Anticorrosion Coating Stability of Thermally Demagnetized Nd-Fe-B Permanent Magnets for Reuse Applications.

Nd-Fe-B-type permanent magnets, containing approximately 30% critical rare-earth elements by weight, are essential components in renewable energy systems (e.g., wind turbines, hydroelectric generators) and electric vehicles. They are also critical for consumer electronics and electric motors in products like energy-efficient air conditioners and home appliances. In light of advancing sustainability goals, the direct reuse of magnets from end-of-life devices offers a promising alternative to energy-intensive and costly recycling methods based on hydro- and pyrometallurgical processes, as well as modern short-loop recycling through hydrogen processing. However, Nd-Fe-B magnets must be demagnetized before they can be extracted from devices. This study explores the effects of thermal demagnetization, performed either in air or a vacuum, on the stability of anticorrosion coatings and the magnetic performance of remagnetized magnets. Corrosion tests were conducted to assess the compatibility of various coatings with thermal demagnetization, identifying those most suitable for future applications involving magnet reuse.

Authors' reply to correspondence on "direct potable reuse and birth defects prevalence in Texas": An augmented synthetic control method analysis of data from a population-based birth defects registry.

Authors' reply to correspondence on "direct potable reuse and birth defects prevalence in Texas": An augmented synthetic control method analysis of data from a population-based birth defects registry.