Resources, Conservation and Recycling: X最新文献

The treatment of ideas of repair in circular economy literature is critically reviewed, revealing instrumental understandings of repair as a tool to extend product life-spans and reduce waste. These framings are interpreted as an expression of the dominant technocratic and post-political discourses of circular economy as an intervention to sustain industrial capitalism in the face of sustainability constraints. The review contrasts these understandings of repair derived from a review of circular economy literature with richer and contested interpretations found in sociological, ethnographic and political literatures examining material repair in practice. Drawing on the emerging sociology of repair and applying more distinct concepts of restoration, remediation, reconfiguration and reconciliation derived from these literatures, the paper argues that the understandings of repair in circular economy literature are limited and restrictive, generally supporting a view of repair as sustaining, consumerist and nostalgic; and thereby overlooking potentially transformative, political and future-oriented roles for repair in a circular economy. In the restorative and remedial modes most commonly understood in the circular economy, repair is seen to enable new forms of capitalist commodification, notably of waste and domestic labour. Learning from contestation in other arenas of repair by contrast, understanding repair as encompassing ideas for reconciliation and reconfiguration, and adopting values of integrity, care and legibility, opens up repair in the circular economy to constructive critical discussion and reflection and offers new insights for policy makers.

Large-scale mining of low-grade ores is energy-intensive and generates vast wastes. It has limited suitability for production of specialist metals that are required in relatively small quantities. An approach that limits environmental impact by restricting mining to high-grade deposits requires the investigation of small ore deposits as alternative sources of metals. The return on investment from small deposits is incompatible with the expensive surveys needed to secure investment and the high costs of managing risk. But increasing energy and transport costs may create space in the market for small-deposit mining with highly-competitive technological solutions. It can be argued that small-deposit mining is ethical because it must involve cooperation between mining companies and local residents who share a collective expectation and responsibility for their quality of life. However, small-deposit mining tends to be a limited, short-term initiative, which requires consideration of the extended ‘afterlife’ of mines. This manuscript is the culmination of five years of cross-sector dialogue and stakeholder engagement activities. It debates what constitutes a small deposit and describes the interactions between mining and manufacturing, investment, environment and society. It reaches the conclusion that technological innovations will support the re-emergence of small deposit mining as an important part of a diverse raw materials production sector. We do not suggest a return to past approaches, to mining of small, high-grade deposits, but a consideration of alternative narratives of localised, community-orientated mining processes, thus giving social, economic and environmental context to the needs of the present day.

The principle of cascading, the sequential and consecutive use of resources, is a potential method to create added value in circular economy (CE) practices. Despite conceptual similarities, no research to date has explored how cascading has been operationalised and how to integrate it with CE R-imperatives (Reduce, Reuse etc.) to facilitate implementation practices. CE practices emphasise value creation and retention, yet, there has been little reflexive examination of explicit and intrinsic value considerations; namely, how allocation choices, i.e. the decision-making process, for resource utilization are made. This paper aims to (1) examine how cascading has been operationalised (empirically and theoretically) to understand its normative underpinnings and value considerations; and (2) integrate cascading with the CE practices in a manner that accounts for the complexities of material allocation choices. Through a literature review of 64 articles from three bodies of literature (CE, cascading and up/downcycling), plus additional material on sustainable development, we show the cascading concept is a suitable framework to direct material uses and provides an overarching concept to integrate with CE R-imperatives. From this, we propose a new theoretical framework that considers the socio-organisational necessities for a CE-cascading system, specifically by deconstructing the allocation choices and exchanges of product material combinations between actor groups. This considers a dual perspective of the physical aspects of materials and the social context in which material allocation is made. The framework transcends individual value chain actor configurations to propose an overarching steering/governance framework, based on the triple-P of sustainability (People, Planet, Prosperity), to examine and direct CE-cascading exchanges, between and above individual users/firms.

Using human excreta derived fertiliser (HEDF) in agriculture reduces dependence on diminishing phosphorus rock reserves, improves soil health, and facilitates sustainable nutrient recycling. Such schemes have particular scope for expansion in peri-urban areas of low-income countries, where large quantities of faecal sludge from on-site sanitation systems are available. However, public acceptability is a critical unknown factor. This study used surveys of 534 peri-urban subsistence farmers in Blantyre, Malawi, to investigate the public acceptability of HEDF. Two factors are highlighted as having a particularly strong association with acceptability: showing a sample of composted, granulated faecal sludge to participants at the start of the survey, and having heard of HEDF before. For instance, almost all participants who were shown the composted, granulated sample and had prior knowledge of HEDF were willing to buy maize grown in HEDF (96%). Conversely, less than a third of participants who had not heard of HEDF before and were not shown the composted, granulated sample were willing to do so (30%). Maize was the most widely accepted crop for use with HEDF, as there is perceived to be little contact between the edible parts and the ground. This suggests that HEDF has the potential to be widely accepted by subsistence maize farmers and the general public in Malawi. However, uptake rates could be substantially improved with public engagement campaigns involving demonstrations or samples of a visually appealing product, and by promoting the concept through channels such as farmer radio programmes or agricultural extension workers.

A circular biobased economy must be able to sustainably manage multiple resources simultaneously. Nutrient (nitrogen, phosphorus, and potassium) recycling and renewable energy production (biogas) can be compatible practices but require substantial transport of heavy organic waste. We combine a spatial optimization model and Life Cycle Assessment (LCA) to explore how Sweden could maximize its use of excreta resources. We use $10\times 10$ km${}^2$ resolution data on the location of animal and human excreta and crop demand and model both optimal biogas plant locations and transport of nutrients to and from these plants. Each type of biogas plant (given 4 realistic mixes of excreta) is then evaluated for global warming potential, primary energy use and financial resource costs. Moving excreta through biogas plants, as opposed to simply reapplying on fields, to meet crop nutrient demands comes at a similar cost but the climate and primary energy savings are substantial. As much as 91% of phosphorus and 44% of nitrogen crop demand could be met via optimally transported excreta and the country would avoid about 1 450 kt of CO₂-eq, save 3.6 TWh (13 000 tera-joules) of primary energy, and save 90 million euros per year. Substituting mineral fertilizers with recycled nutrients results in savings across all indicators, but the added energy and avoided greenhouse gas emissions associated with biogas production make a large difference in the attractiveness of nutrient recycling. Although the numeric values are theoretical, our results indicate that carefully coordinated and supported biogas production could help maximize multi-resource benefits.

Rainwater harvesting systems (RWHS) are increasing in popularity because of their ability to alleviate water pressure on centralized systems, minimize or delay rainfall runoff, and fit relatively easily in both the centralized/decentralized infrastructure organization. Adequately sizing RWHS is critical to optimizing their operation because under-sizing results in systems that are unable to provide a sufficient, reliable source of water while oversizing increases the capital costs incurred with limited marginal benefits and poses potential water quality risks.

In this paper, we conduct a systematic literature review to assess the state-of-art in the field of optimization of domestic rainwater harvesting systems. Sizing of storage is identified as the most important objective of optimization, yet sizing for cost is the most frequently implemented outcome of optimization. Optimizing for a local maximum is often favored over simulation-based optimization methods that produce global maxima. To derive more realistic sizing estimates, future optimization studies will have to take into account greater variation in water demands as well as various climate change scenarios, especially given that rainfall frequency and quantity are critical design variables of a rainwater harvesting system.

Car electronics form an extensive yet untapped source for secondary critical raw materials. To seize their recycling potentials it is imperative to understand how the number and volumes of car electric and electronic (EE) devices are affected by trends in: i) car typology, ii) penetration and integration of automobile electronic control systems (AECS), and iii) unit mass of EE devices. We used a layered dynamic material flow analysis (MFA) incorporating comprehensive data series to analyze the aforementioned trends and their influence on end-of-life mass flows of two automobile EE devices in Switzerland over the period 1975 to 2015. We found that there has been an increased penetration of the EE devices coinciding with a replacement of unifunctional devices by multifunctional ones (integration) and a decrease in their unit mass (downsizing). Both penetration and unit mass changed most rapidly in the 1990s and have flattened after the year 2000. Penetration outweighed integration and downsizing, so that before stabilizing, it caused a rapid increase in the mass flows of the EE devices. Due to the long lifetime of cars, changes in penetration, integration and downsizing are still evident at the end-of-life flows, but can be expected to slow down considerably between 2015 and 2025. The results demonstrate that monitoring of the trends at the car inflow, in combination with a dynamic MFA, can be used to anticipate changes in end-of-life flows 10–20 years before they occur and to timely inform recycling policies.