Circularity in Practice: Review of Main Current Approaches and Strategic Propositions for an Efficient Circular Economy of Materials

This paper aims to summarize, propose, and discuss existing or emerging strategies to shift towards a circular economy of materials. To clarify the landscape of existing circular practices, a new spectrum is proposed, from product-based strategies, where entire products go through several life cycles without being reprocessed, to material-based approaches, extracting, recycling, and reprocessing materials from the waste flow. As refillable packaging does not lose any functionality or value, when re-used through many life cycles, product-based strategies are globally extremely efficient and must be promoted. It appears however that their implementation is only possible at the scale of individual products such as packaging containers, relying on the cooperation of involved companies and consumers. It appears more and more urgent to focus as well on a more systematic and flexible material-oriented scheme. The example of circular glass recycling is a success in many countries, and technologies become nowadays available to extend such practices to many other materials, such as rigid plastics. An ideal would be to aim at an economy of materials that would imitate the continuous material cycle of the biosphere. Technological and business strategies are presented and discussed, aiming at a relevant impact on circularity.

Approaches and Policies to Promote Zero-Waste City Construction: China’s Practices and Lessons

The rapidly growing output of solid waste has brought tremendous pressure to urban development. China launched an action plan known as “Zero-waste city” (ZWC), that refers to an urban development model aimed at reducing the generation of and enhancing the recycling of solid waste, in order to alleviate environmental impacts. Eleven cities and five special zones achieved positive results of solid waste management were selected as pilot areas for exploring empirical methods until 2019. The practices and lessons of the pilot cities need to be deeply analyzed and summarized, so as to promote successful models, learn lessons and better implement the policy comprehensively for other cities. This study presents a review of China’s ZWC policies and practices with constructive suggestions for further development. Based on the policy objective of ZWC and the field investigation of solid waste flow, five crucial approaches to developing ZWC are proposed, namely, solid waste reduction throughout the industrial chain, collaborative treatment of classified municipal solid waste (MSW), efficient utilization of agricultural waste with multiple purposes, safety control of hazardous waste flow, and optimization of market mechanisms. The case study demonstrates that the five paths are appropriate to Xuzhou city. However, deficiencies in MSW classification, pesticide packaging waste collection systems, solid waste product application, management, and policymaking, have emerged. Regulatory prohibitions, extended producer responsibility and market vitality should be adopted to improve the collection, transportation, and utilization of solid waste. Key findings from this research are to summarize crucial paths toward fulfiling ZWC goal, and to reveal some successful practices of, and lessons from ZWC construction by case studies. This study provides a method to further implement zero solid waste management in a targeted manner. The recommendations drawn from the study, which include law, market and institutional measures, may contribute to the achievement of developing sustainable cities.

A Global Map of Human Sewage in Coastal Ecosystems

Prodigious quantities of nitrogen from human waste flow into coastal waters, a study of nearly 135,000 watersheds reveals.

Component-Based Model for Building Material Stock and Waste-Flow Characterization: A Case in the Île-de-France Region

Building demolition is one of the main sources of waste generation in urban areas and is a growing problem for cities due to the generated environmental impacts. To promote high levels of circular economy, it is necessary to better understand the waste-flow composition; nevertheless, material flow studies typically focus on low levels of detail. This article presents a model based on a bottom-up macro-component approach, which allows the multiscale characterization of construction materials and the estimation of demolition waste flows, a model that we call the BTP-flux model. Data mining, analytical techniques, and geographic information system (GIS) tools were used to assess different datasets available at the national level and develop a common database for French buildings: BDNB. Generic information for buildings in the BDNB is then enriched by coupling every building with a catalog of macro-components (TyPy), thus allowing the building’s physical description. Subsequently, stock and demolition flows are calculated by aggregation and classified into 32 waste categories. The BTP-flux model was applied in Île-de-France in a sample of 101,320 buildings for residential and non-residential uses, representative of the assessed population (1,968,242 buildings). In the case of Île-de-France, the building stock and the total demolition flows were estimated at 1382 Mt and 4065 kt, respectively. For its inter-regional areas—departments—, stock and demolition waste can vary between 85 and 138 tons/cap and 0.263 and 0.486 tons/cap/year, respectively. The mean of the total demolition wastes was estimated at 0.33 tons/cap/year for the region. Results could encourage scientists, planners, and stakeholders to develop pathways towards a circular economy in the construction sector by implementing strategies for better management of waste recovery and reintegrating in economic circuits, while preserving a maximum of their added value.

A critical review of household recycling barriers in the United Kingdom

The UK recycling rate fluctuates between 45% and 47% and has consistently failed to meet the 65% target set by the post-Brexit Resource and Waste Strategy. Understanding the issues surrounding the low recycling rate in metropolitan cities in the United Kingdom will help to overcome these recycling challenges. The review examines the current situation with regard to the recycling rate and tonnage of waste produced in the United Kingdom based on available secondary waste flow data and explores different barriers related to household recycling. Many areas giving rise to the recycling challenges have been identified, including waste policy constraints, lack of effective communication, public engagement, physical barriers, service constraints, human factors and socio-economic barriers. The literature review reveals that factors such as waste policy, communication and physical factors were the most important aspects in influencing recycling rate or output. It is concluded that a multi-dimension intervention is required, which includes a thorough review of waste policy, a more stringent enforcement, an improved communication strategy and a more integrated planning development policy to mitigate issues affecting the United Kingdom’s low recycling rate or output. This approach will propel the local authorities to launch or initiate effective recycling management and to put in place the required infrastructure to facilitate effective recycling activities.

End-of-life tire management: a critical review

Environmental and social awareness are the key elements of the sustainable tire industry. End-of-life tire (ELT) waste flow is an important environmental problem worldwide since it produces severe air, water, and soil pollution issues. Significant advancements have been made in ELT management in the last few years. As a result, ELTs should not only be regarded as waste but also as a source of environmentally friendly materials. Besides, sound ELT management has vital importance for circular economy and sustainable development. Over the last decade, ELT management has attracted many researchers and practitioners. Unfortunately, a comprehensive review of the ELT management area is still missing. This study presents the first critical review of the whole ELT management area. It aims to present an extensive content analysis overview of state-of-the-art research, provide its critical analysis, highlight major gaps, and propose the most significant research directions. A total of 151 peer-reviewed studies published in the journals between 2010–2020 are collected, analyzed, categorized, and critically reviewed. This review study redounds comprehensive insights, a valuable source of references, and major opportunities for researchers and practitioners interested in not only ELT material flow but also the whole waste management area. Graphical abstract

National and subnational outcomes of waste management policies for 1718 municipalities in Japan: development of a bottom-up waste flow model and its application to a declining population through 2030

Japan has been promoting 3R (reduce, reuse, and recycle) policies for several decades, but the recycling rate of the whole country has leveled off, and more effective policies are needed. At the same time, municipalities have been implementing measures for municipal waste management considering their specific regional conditions, but the relationship between the municipalities’ policy inputs and national policy output is unclear, which causes difficulties in setting national targets and identifying effective policies. We, therefore, developed the Municipal Input and National Output Waste (MINOWA) model, which represents the municipal waste flows of all 1718 municipalities in Japan. The model enables users to establish various 3R measures at the municipal level and estimate their effects at the national level. Using the model, we estimated the flows under business-as-usual (BaU) and additional-measure scenarios that extended the use of conventional policies to 2030. The results revealed differences in the policy effects between areas with different populations. In addition, the results showed that the extension of conventional measures will be insufficient to achieve national goals. The developed model links municipal policies, regional characteristics, and national policy and goal-setting in an integrated framework, and supports ways to find more effective policies.

Consideration of Complexity in the Management of Construction and Demolition Waste Flow in French Regions: An Agent-Based Computational Economics Approach

For each region of France, there is currently a program to implement a plan for regional prevention and management of construction and demolition waste (CDW) used in the buildings and public works (e.g., roads) sector, also called the BTP (from the French Bâtiment et Travaux Publics) sector. To implement such a plan, its complexity must be considered; i.e., account (a) for how different scales are endogenously connected and (b) for decision-making rules at each scale being introduced. However, this complexity has rarely been taken into account in the literature. Using the PACA region as a case-study, this paper presents the first results of modelling that determines a hypotheses for the geographic distribution of the road renovation rate in each municipality (microscale) and Department (mesoscale) in a region of France. Such a renovation requires recycled aggregates (gravel) and asphalt supplies simultaneously. To consider this endogenous connection between scales, the model at the micro-scale must also be calibrated so the simulated values emerging at a higher-scale approach a supply–demand balance. We also discuss the transposition of the model to another French region (Ile-de-France). The method we used is the Agent-based Computational Economics (ACE) modelling approach. In addition, the coherent interplay between scales is determined by an approach called pattern-oriented modelling (POM). Our research revealed, at a thematic level, that for a circular economy to develop, the network of facilities in the territory is very important, and effective commercialization of secondary resources is major in the areas that group together recycling platforms and nearby asphalt plants. At a methodological level, our research revealed that in any multi-level modelling exercise, POM can be seen as an essential approach to accompany the ACE approach, particularly for a macroeconomic (here macro = regional) looping of a model designed at a microscale. However, convincing the BTP sector to integrate ACE/POM as a full part of a methodological support for regional prevention and management of CDW remains a challenge

Waste Flow, Recycling, and Greenhouse Gas Emissions: a Case Study of the Comparative Environmental Impact of Recycling Approaches on a College Campus

Municipal solid waste flow was modeled and measured at the U.S. Naval Academy to understand not only the movement of waste, but also the policies and economic incentives that have led to the current waste management plan at the Academy. The study contains four primary thrusts: regulatory policies, waste production and recycling levels, collection and sorting processes, and disposal and material recovery. Waste hauling data for a one-year period in 2017-2018 showed that the institution generated approximately 300 tons of total waste each month and recycled approximately 11-15% of that waste. From directly measuring waste across campus, approximately 36% of the non-recyclable waste stream contains recyclable materials. Most recyclable materials that ended up in the non-recyclable waste stream were plastics and cans, and came from academic spaces. However, a test academic space that gave access to waste bins only conjoined with recycling bins showed a substantial reduction in recycling infiltrating the non-recyclable waste stream. The study also shows how the handling of waste has evolved over recent years. Since the mid-2000s, the Academy has shifted to relying on contractors to sort and transport waste. Currently, five private contracting agencies are utilized in the waste flow stream after materials leave the Academy. To assess environmental impact, a life cycle assessment model was constructed based on the movement of waste to estimate the possible effects of the current recycling program on carbon equivalent emissions. The results indicate that current practices result in over 500 metric tons of carbon equivalent savings over the long-term during the one-year measurement period. The model also shows that by reducing recycling infiltrates into the waste stream, an additional 1000 metric tons of carbon equivalent savings are possible. Economic incentives were evaluated at each of the four sections of the waste process model, and analysis suggests that focusing on behavioral change strategies at the waste generation and initial collection and sorting levels holds the best promise for increasing levels of recycling, reducing landfilled waste, and reducing net carbon emissions in accordance with DOD policy goals.