Considering the importance of waste metals for the transition to circular economies, this study follows a bio-inspired approach to evaluate their material and monetary global trade patterns for sustainability and equity. Between 2000 and 2022, the global trade grew by 5 % in trading countries, by 37 % in trade links, by 71 % in material flows, and by 569 % in economic flows. Driven by indirect effects, the average circulation of material and monetary flows ranged between 21.8–34.9 % depending on the demand or supply perspective but showed a declining trend. Due to homogenization, high network redundancy, and low network efficiency the trade remained robust yet outside the "window of vitality" characterizing natural ecosystems. A few, mostly high-income countries dominated the market, consolidating imports of high-value metal waste mostly from low- and middle-income exporters. Policies should address circularity and trade inequities, accounting for environmental and social ramifications throughout the lifecycle of products and materials.@en

The inclusion of the informal recycling sector (IRS) in a circular economy (CE) is challenging and it is gaining increasing attention by the academic community in an exponential yet fragmented way. In this narrative review, we demarcate the direct and indirect contributions of the IRS to various domains of the CE by drawing knowledge from relevant literature. First, we capture the modi operandi of different forms of recycling value chains into a typology. We do so based on distinct foci and policy approaches towards the IRS which have been adopted across different countries. Second, we synthesize various threads of information on reported forms of collaboration, tensions, and challenges in the context of urban waste management, into a conceptual framework to facilitate transitions towards circular and inclusive wise-waste systems. Finally, we discuss important aspects related to circular business models and integration approaches towards the IRS, and we propose avenues for further research.

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Chinese cities are experiencing rapid urban development while facing severe challenges of environmental pollution. China's central government has proposed several policies to reduce urban waste. However, little is known about the adoption of these policies. Here, we raise the question how can circular policies be classified, and how can this classification be applied to cities in China that wish become zero-waste cities? We develop a framework to classify urban waste policies according to: (a) the “5R” principles (“Rethink”, “Reduce”, “Reuse”, “Recycle”, and “Recover”), (b) four types of waste (industrial, agricultural, municipal, and hazardous) and (c) six types of policy instruments (legal, economic, network, communication, innovation and projects). We use this framework to analyze urban waste policies implemented by sixteen zero-waste demonstration projects in China. The present study emphasizes combinations of policy instruments, “R” strategy and waste type in the implementation of zero-waste policies. We find that the “Rethink”, “Reduce”, and “Recycle” principles have been widely implemented by local authorities in contrast to the principles “Reuse” and “Recover”. Local governments address waste management by embracing regulations, innovation instruments, and project arrangements, while network-based, economic, or communicative policy instruments are used less often. Based on the results we suggest that local governments embrace a comprehensive approach to the use of the “5R” principles and deploy a diverse portfolio of policy instruments.@en

For many islands, the answer to the question “why a locally, self-sustaining, and regenerative economy is needed?” is clear. The struggle often lies in the “how”. Here, we argue that tools from regenerative economics, which follow an island economy-as-an-organism analogy, offer valuable and complementary insights to socio-metabolic research. Indicators from flow-based and information-based ecological network analysis can quantify properties of an island's socio-economic metabolism (SEM) which are related to cycling, resilience, and degree of mutualism, among others. To illustrate the applicability of these methods, we select Samothraki in Greece as a case study. Results show that over the years the island became very efficient in streamlining imported resources, experiencing physical growth as indicated by a substantial increase in its total material throughput. This growth was attributed to a high degree of order (i.e., network efficiency) endowed by the constraining (ordered) part of the linear structure of the island's SEM. The disordered part of its SEM which is related to resilience, played a much smaller role which became progressively more important over the years, albeit to a limited degree. While the island exhibits an increasing trend in its robustness, its value over the years studied was well below what is typically observed for healthy natural ecosystems, and its current SEM has a very low ability to generate internal flow activity and cycling of resources per unit input. This limited robustness is due to the island's dependency on imports but also due to its linear SEM which had a very small number of feedback loops in its network. A scenario analysis showed that a reticulated network structure would theoretically endow the island with increased resilience, and hence robustness, by allowing for more internal resource flow activity to be circulated as regenerative re-investment. This article highlights that methods from regenerative economics can be used as diagnostic tools to assess and monitor the impact of strategies related to circular economy interventions on network properties, and to illuminate their effect on the regenerative potential of islands.

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The potential for carbon emissions avoidance through post-consumer recycling has been highlighted in the "Zero-Waste City" initiatives in China, which call for increasing household participation in the community recycling programs. A shift from a facility-oriented strategy to behavior-oriented norm building at the community level provides the local niches for emerging business models in post-consumer recycling. This paper proposes a framework based on the Theory of Planned Behavior to simulate the impact on the participation rate of households in community-based recycling program in the context of different recycling business models in Beijing. Firstly, a questionnaire survey was conducted in 2021 in Beijing (N = 1153) to test the key factors which affect household recycling behavior. Secondly, an agent-based model for community-based recycling which was developed in 2016 has been updated to incorporate the institutional change in the development of zero-waste city initiatives. Scenario analysis is adopted to compare the effects of introducing two new business models to the baseline situation that is prevalent at present. The settings for the two new business models represent the diversified directions of the upgrading of urban recycling sector: one is to improve the intelligence of the collection facilities to save labors, and the other is to involve the informal recyclers to provide door-to-door collection services in person so as to save time for the residents. Additional scenario shows the effects of norm-based solutions in combination with the two strategies addressed above in the long run. The simulation results show that the potential for carbon emissions reduction through post-consumer recycling in Beijing can range from 1 million tons per year at the basic scenario to more than 4.5 million tons per year in the community level norm-based solution scenario. In conclusion, the proposal for sustaining the community-based new business models through the capture of value in the carbon emission reduction is put forward as a guideline for urban recycling infrastructure design.@en

Considering its relatively low circularity rate (11.8% in 2019), the EU set several waste management targets as part of its roadmap to a circular economy yet the decision about which transition pathway to follow is not trivial. The maximization of circularity in human made systems is intended to function as a catalyst for this transition albeit at the risk of establishing fragile techno-economic systems. To provide insights for a balanced transition to a circular economy its link with the ecological concepts of “resilience” and “robustness” is illuminated by assessing the theoretical robustness of the material and energy flow networks of the EU27 countries between 2010-2018 using Eurostat data. Results show that despite the high degrees of order (efficiencies) which all European countries developed over the years studied, none of them achieved near-maximum robustness. The identified relationships between the average circularity rate and the average energy efficiency with the theoretical robustness of these material and energy flow networks (for the years studied), respectively, suggest that ascendency analysis is a credible tool for supporting policy making. Both on a national and on a local level for developing circular and robust urban waste management systems given data availability. The contribution to the underlying theory of ascendency analysis is the introduction of the concepts of “technological boundaries” and “windows of efficiency” of these human-made networks which are juxtaposed with the “window of vitality” that is often used to describe healthy natural ecosystems. Finally, the limitations of ascendency analysis and directions for future research are presented.@en