查看更多>>摘要：Electronics require a complex composition and energy-intensive manufacturing. Yet, most of the world's waste electrical and electronic equipment is not collected and recycled. Circular economy (CE) strategies can reduce the loss of materials and environmental footprint in electronics. Resource efficiency indicators - typically defined as benefits (handprint) over burdens (footprint) - can measure materials' life cycle performance. This paper aims to develop resource efficiency indicators that show the benefits and burdens of materials use. We illustrated the indicators with a case study of four materials (aluminium, copper, iron, and plastics) embedded in laptops. The study includes scenarios with different CE strategies: energy recovery, recycling, refurbishing, and reuse. The scenarios show the use of the materials in several cycles of laptops over a 25-year time horizon. Generally, scenarios with cycles of refurbishment and reuse showed improved resource efficiency compared to recycling scenarios. Compared to energy recovery the improvement was up to 189% (refurbishment) and 157% (reuse) in the case of aluminium. Nonetheless, it is remarkable that the average resource efficiency results showed a preference for refurbishing over reuse during 25 years. The result is limited to a shorter functional inuse time of reused laptops. This analysis is relevant for a CE, where the value of materials should be kept for as long as possible. Our methodology expands the traditional one-cycle perspective by measuring the use of materials for 25 years. Policy-makers can use our indicators to assess CE strategies for several product cycles that keep materials in use lowering environmental impacts.
Sinha, R.Thomas, J. -B. E.Strand, A.Soderqvist, T....
11页
查看更多>>摘要：Anthropogenic consumption of nitrogen (N) and phosphorus (P) has pushed their respective planetary boundaries beyond a safe operating space causing environmental problems, and simultaneously, the depletion of finite mineral P resources is of growing concern. Previous research has found that marine biomass such as kelp, reed and mussels have a high potential for taking up N and P, which could potentially contribute both to alleviating environmental problems and recirculating P from marine environments back to human consumption systems. This paper thus examines these nutrient flows and the extent to which marine biomass can contribute to close the loop. The study utilizes an element flow analysis (EFA) to establish the mapping of N and P flows and explore plausible scenarios of biomass utilisation by 2030 and 2050 for P loop closure in Sweden. The current uptake of P and N through the seven marine biomass cases (mariculture of mussels on both the Swedish east and west coasts, kelp and ascidians and the harvest of wild oysters, beach-cast and reed) contributes to 1.1% and 0.3% respectively of the full loop closure (relative to 2016 loading). Approximately 22% of the total P (and 23% N) uptake (in the biomasses) is currently being used in products, while the rest remains unused. The plausible future scenario for 2050 expects to contribute to around 10% P and 2.8% N loop closure (relative to 2016) if all nutrients in the uptake are used.
查看更多>>摘要：Numerous indicators have been suggested as tools for assessing progress towards the circular economy (CE). However, it is unclear what specifically is captured by CE indicators and few studies have tested them on real cases. This review addresses this gap by describing and comparing the resource-related effects captured by existing resource-based product-level indicators and suggesting recommendations for their use and further development. First, the flows and processes quantified by product-level indicators are mapped on a novel flowchart model, which can also be used to select and develop indicators. Second, the indicators are tested on seven real cases. Third, indicator and life cycle assessment (LCA) results are compared. A significant divergence of indicators' scope is found, where most capture a limited part of the product system. Moreover, important aspects of the CE are not captured: no indicator accounts for resource use in the use phase and there is limited attention to lifetime extension strategies. Additional limitations are the difficulties to assess multiple use-cycles and that most indicators cannot capture absolute mass variations, thus neglecting mass reduction strategies. The testing reveals that using a set of single-focus indicators may be necessary to outline trade-offs. Multi-focus indicators are sometimes harder to analyse but provide a more comprehensive assessment. The testing also illustrates that indicator and LCA results are not necessarily aligned. The latter provides information on environmental impacts and can point to trade-offs between impact categories such as climate change, resource use and land use, indicating that CE indicators cannot easily replace LCA.
查看更多>>摘要：Resource use in the country of final demand has severe environmental impacts in other distant countries and regions through resource exploitation. In the narrative of telecoupling, the land disturbance caused by economy-wide international trade has been widely addressed using a multi-regional input-output analysis, but not sufficiently considering the telecoupled land use associated with a specific manufactured product. In this study, using the total material requirement, a new methodology is proposed for evaluating telecoupled land disturbances induced by manufacturing a given product in a given country. This product-focused method is a hybrid approach based on the integration of inventory data of a given product (bottom-up) and the global trade database (top-down). The developed methodology was applied to evaluate the multi-regional land disturbances induced by the production of gasoline vehicles (GVs), battery electric vehicles (BEVs), hybrid electric vehicles (HEVs), and fuel cell vehicles (FCVs) in Japan, as a case study. Finally, the implication is further discussed from the perspective of supply risk, governance, and corporate social responsibility. It was found that the transition of automobile technology in Japan results in changes in the countries and regions most exposed to the telecoupled land disturbances: i.e., from Australia (26% for GVs) to Chile (27% for BEVs) and South Africa (20% for FCVs). The algorithm developed is relatively simplified so that it can be readily implemented to determine the telecoupled land disturbances associated with any product in any country for a sustainable interaction in their mineral trade with other distant countries and regions.
查看更多>>摘要：Printed circuit boards (PCBs) are an essential and central component of electronic waste. The rapid depletion of natural resources, massive generation of end-of-life PCBs and inherently metal-loaded values inevitably call for recycling and recovery. This review critically discusses the systematic and sequential processes adopted for PCB metallic recoveries via physical, pyrometallurgical, hydrometallurgical, and combined technologies. Pre treatments play a decisive and significant role in upgradation and efficient metal extraction. A novel combination of different pre-treatments and hybrid thermal-chemical routes are often reported for improved separation efficiency and performance. Selective recovery (using solvent extraction, precipitation, polymer inclusion membrane, adsorption, ion exchange) of high purity product from multi-elemental leach solution has recently gained interest and is reviewed. Current recycling techniques at a commercial scale are preferably based on pyrometallurgy (smelting-refining), where electronic waste is only a fraction of the total feed stream. Electronic components such as monolithic ceramic capacitors, tantalum capacitors, integrated circuits, and central processing units mounted on the PCBs are important due to precious metals' presence. The futuristic recycling perspective should treat base and precious metal-rich components separately with minimal environmental effect, end product usage, and maximum economic benefit. Sustainable processing routes for converting discarded PCBs into value-added products should also be attempted, as amplified in this review. An integrated, definite framework for full resource recovery from waste PCBs was proposed.
Hernandez-Betancur, Jose D.Martin, MarianoRuiz-Mercado, Gerardo J.
13页
查看更多>>摘要：The presence of chemicals causing significant adverse human health and environmental effects during end-of-life (EoL) stages is a challenge for implementing sustainable management efforts and transitioning towards a safer circular life cycle. Conducting chemical risk evaluation and exposure assessment of potential EoL scenarios can help understand the chemical EoL management chain for its safer utilization in a circular life-cycle environment. However, the first step is to track the chemical flows, estimate releases, and potential exposure pathways. Hence, this work proposes an EoL data engineering approach to perform chemical flow analysis and screening to support risk evaluation and exposure assessment for designing a safer circular life cycle of chemicals. This work uses publicly-available data to identify potential post-recycling scenarios (e.g., industrial processing/use operations), estimate inter-industry chemical transfers, and exposure pathways to chemicals of interest. A case study demonstration shows how the data engineering framework identifies, estimates, and tracks chemical flow transfers from EoL stage facilities (e.g., recycling and recovery) to upstream chemical life cycle stage facilities (e. g., manufacturing). Also, the proposed framework considers current regulatory constraints on closing the recycling loop operations and provides a range of values for the flow allocated to post-recycling uses associated with occupational exposure and fugitive air releases from EoL operations.
查看更多>>摘要：Expanding the curbside collection system for household plastic packaging could help in accomplishing the ambitious recycling targets set by the European Union. In this study, the effects of such expansion in terms of quality and quantity of sorted plastic waste fractions were investigated. By applying a validated sorting model, the flows of packages in Belgium from their use phase until the output of the sorting plant and the quantity and composition of sorted waste fractions were simulated. These data were subsequently used to calculate existing performance indicators, such as grade and recovery, as well as new indicators, such as the Simpson's Diversity Index (SDI), which is a measure for the compositional diversity of sorted waste fractions. The highest SDI was calculated for the fraction named 'other films', namely 82%, showing that this fraction comprised the most diverse polymer mixture. Results indicated that certain sorted fractions achieve high product grade levels, e.g. more than 99% for the PS rigid fraction, whereas others had significantly lower product grades of approximately 80% for the PE films. Material Flow Analysis showed that by expanding the collection portfolio the collection rate of plastic packaging increased from 33.6 to 64.4 m%, of which 77.3% is simulated to be separated in the targeted waste fractions. However, this will be insufficient to meet the recycling target of 50% by 2025 as in total only 49.8% of plastic packaging is sorted correctly. Hence, additional improvements in both recycling technologies and packaging design are needed to further increase plastic recycling rates.
查看更多>>摘要：In the fight for reducing GHG emissions from road transport, electromobility has gained huge attention in recent years. However, the higher adoption of battery electric vehicles in the transportation sector will increase the demand for battery materials, including nickel, lithium, copper, cobalt, and graphite. Therefore, this study estimates the future lithium-ion batteries (LIBs) market in the USA and China and its influences on the materials demand, end of life reaching of LIBs material, and second use based on three different scenarios. For this purpose, a multidimensional scenario analysis was developed for 2012 to 2030 to analyze the material flows from batteries of passenger electric vehicles in China and the USA. The result suggests strong benefits of a circular battery values chain. The results from three scenarios showed that in 2030 there would be around 5-7 kt of recovered Li, 35-60 kt of recovered Ni only in China. Based on the economic evaluation of LIBs in scenario 2, it was found that recovered nickel would have the economic values of 725 million US dollars only in 2030 in China. Through the second use assessment of LIBs in the third scenario, where 50% of used batteries were assumed for second use application, it was found that around 33 GWh batteries would be available for second use only in 2030 in China. Therefore, the larger portion of used LIBs should be utilized for a second life as it could further delay the recycling of LIBs, which can further give time to the government so that the improved and larger recycling infrastructure could be built to tackle a higher amount of coming used LIBs.
查看更多>>摘要：This paper explores the disjuncture between consumers' expressed preferences for ecologically benign packaging and their subsequent purchase decisions. We investigate consumers' attitudes towards compostable bio-based food packaging, in contrast to fossil-based plastic packaging, framing our study within analysis of implicit attitudes. We address a gap in knowledge about the moderating effects of consumers' reported health consciousness on the relationship between implicit health associations with compostable packaging and subsequent purchase intentions. Specifically, across four studies employing Implicit Associations Tests (IATs), we analyse the relationship between implicit and explicit attitudes, relating packaging associations with consumers' behavioural intentions. Our findings confirm positive implicit (and explicit) perceptions of compostable bio-based packaging (vs. fossil-based plastic) regardless of the healthiness of the food contained. This is reflected in consumers' purchase intentions. We build on this to incorporate the effects of consumers' self-reported health consciousness. We find that low health-conscious consumers are more likely to be guided in their compostable packaging decisions by their unconscious and automatic health-packaging associations, than consumers with high health consciousness. We contribute to policy discussion about effective ways of reducing fossil-based plastic packaging use and note that environmental claims for non-plastic alternatives aimed at consumers with low-health consciousness should make appeals based on health benefits, tapping into implicit attitudes to evoke automatic responses.
查看更多>>摘要：To promote diatom-based biofuel productions in clean energy, this paper explores the potential of using biosilica as a renewable and regenerative byproduct from diatom-based biofuel production in cementitious materials. High-purity diatomite (DE), a biosilica model compound, is selected to investigate the microstructure and durability performance of diatom-based cementitious composites. The replacement of portland cement with 30 wt.% DE significantly enhances the resistance to leaching, reduces the rapid chloride permeability, but increases the drying shrinkage at early ages. The microstructure of DE-containing matrix is refined due to the lime-silica reaction, and the interfacial transition zone of DE-containing concrete is densified. Overall, the DE-induced microstructural changes enhance the durability performance of DE-containing cementitious composites, which in turn demonstrates the feasibility of using biosilica as a sustainable cement substitute. The use of biosilica from diatom-based biofuel production can potentially reduce the CO2 emissions of carbon-intensive concrete production and promote the development of clean energy.
NSTL
Elsevier