Showing papers in "Resources Conservation and Recycling in 2019"

Circular economy indicators: What do they measure?

Abstract: Circular Economy (CE) is a growing topic, especially in the European Union, that promotes the responsible and cyclical use of resources possibly contributing to sustainable development. CE is an umbrella concept incorporating different meanings. Despite the unclear concept, CE is turned into defined action plans supported by specific indicators. To understand what indicators used in CE measure specifically, we propose a classification framework to categorise indicators according to reasoning on what (CE strategies) and how (measurement scope). Despite different types, CE strategies can be grouped according to their attempt to preserve functions, products, components, materials, or embodied energy; additionally, indicators can measure the linear economy as a reference scenario. The measurement scope shows how indicators account for technological cycles with or without a Life Cycle Thinking (LCT) approach; or their effects on environmental, social, or economic dimensions. To illustrate the classification framework, we selected quantitative micro scale indicators from literature and macro scale indicators from the European Union 'CE monitoring framework'. The framework illustration shows that most of the indicators focus on the preservation of materials, with strategies such as recycling. However, micro scale indicators can also focus on other CE strategies considering LCT approach, while the European indicators mostly account for materials often without taking LCT into account. Furthermore, none of the available indicators can assess the preservation of functions instead of products, with strategies such as sharing platforms, schemes for product redundancy, or multifunctionality. Finally, the framework illustration suggests that a set of indicators should be used to assess CE instead of a single indicator.

A literature review on green supply chain management: Trends and future challenges

Abstract: This study aims to review the literature in green supply chain management (GSCM) published from 1998 to 2017 and presenting insights and directions for future research. The study collects data from Scopus and ISI Web of Science databases and objectively selects 880 papers and conducts metadata analysis. In addtion, 236 papers from ISI Web of Science is analyzed to present the insights along with the classifications of the literatures based on content analyses, which comprises of conceptual development, drivers and barriers, collaboration with supply chain partners, mathematical and other optimization models, and assessment of green supply chain management practices and performance. The study finds that research on drivers or barriers analysis of green supply chain management reveals a declining trend while there is a growing trend of applying mathematical optimization models for enhancing decision making in pursuit of environmental performance. Moreover, the study finds a consistent growth in the evaluation of green supply chain management practices and performance. Though, the concept of green supply chain management started gaining popularity among academicians from the beginning of the 20th century, this study finds a sharp growth of publications on the topic after 2010 until now. This study identifies influential authors, top journals, top contributing countries, top contributing institutions and contribution by disciplines. This study presents a comprehensive but straightforward conceptual model of green supply chain management. The findings and future research directions of the study offers a new avenue for further exploration and contribution to this discipline.

Towards sustainable development through the circular economy—A review and critical assessment on current circularity metrics

Abstract: The circular economy (CE) is perceived as a sustainable economic system where the economic growth is decoupled from the resources use, through the reduction and recirculation of natural resources. In the shift towards the CE, quantifying the circularity of products and services (or their contribution to the CE) is crucial in designing policies and business strategies, and prioritizing sustainable solutions based on evidence. New circularity metrics are being developed for that purpose, but they often present contradiction in both form and content, which contributes to confusion and misunderstanding of the CE concept. This review aims to map methodological developments regarding circularity metrics for products and services, in order to: (1) identify the foundations of circularity metrics used so far and their applications, (2) evaluate the validity of current circularity metrics, based on predefined requirements and a CE definition anchored in the sustainability concept, and (3) provide recommendations on how to measure circularity. The literature search provided a wide variety of CE metrics being developed and applied (seven measurement indices, nine assessment indicators and three assessment frameworks). However, none of them are addressing the CE concept in full, potentially leading to undesirable burden shifting from reduced material consumption to increased environmental, economic or social impacts. Additionally, new metrics under-represent the complexities of multiple cycles and the consequences of material downcycling. Circularity metrics intended to sustainable decision making should be comprehensive enough to avoid burden shifting, and clearly indicate how the benefits of recycling are allocated between the primary and secondary products.

The effects of activated biochar addition on remediation efficiency of co-composting with contaminated wetland soil

Abstract: Unreasonable disposal of organic wastes has caused great problems, including occupying land, affecting organoleptic feeling and causing environmental re-contamination. By incorporation of biochar as raw material into co-composting with agricultural organic matter, it not only can the wastes recycling be realized, but also can the remediation efficiency of multi-element contaminated soil be improved to reach land reclamation. Activated biochar was added for investigating the influences on physico-chemical properties of soil during composting. The concentrations of available metals and arsenic in soil were detected on great reduction in the treatment of biochar-blended composting. Based on the stronger adsorption and microbial activity induced by biochar, the initial content of available PAHs in wetland soil decreased to remain about 3.03% and 5.47% below the control (9.47%) in co-composting added with activated and fresh biochar, respectively. It was related to the observation with improved microbial number as well as optimized fungi/bacteria gene copy number ratio by activated biochar addition, which is conducive to vegetation replanting of contaminated land. The feasibility of applying biochar into co-composting with contaminated soil was confirmed by not only the high remediation efficiency but also the sustainable recycling of agricultural waste.

The composition, recycling and utilisation of Bayer red mud

Abstract: Red mud or bauxite residue is a solid waste generated from the Bayer process. The disposal of red mud leads to a serious environmental threat because of its tiny particle size and high alkaline value. The utilisation and recycling of red mud is currently a crucial issue and needs to be addressed as soon as possible. This study demonstrates the different methods and techniques recently analysed or suggested for the consumption of bulk red mud to maintain a sustainable environment. The potential utilisations of red mud include valuable metal recovery, the preparation of construction materials and as an alternative catalyst for diverse processes, including hydrodechlorination, hydrogenation and hydrocarbon oxidation. In addition, the red mud can also be used to control environmental pollution, such as in wastewater treatment, soil remediation and the purification of flue gas. However, the proper utilisation and recycling of red mud has a number of shortcomings: pyro-metallurgical recovery involves high energy costs; large volumes of acid by-product needing to be neutralised after the leaching process; the fine particle size of red mud; and the necessity of pre-treatment in some methods. Although many studies have investigated the potential utilisation of red mud, most of them have concentrated on lab-scale studies. Therefore, a large-scale investigation of the recycling and utilisation of red mud needs to be explored. Moreover, an appropriate cost-benefit analysis of the existing technologies needs to be examined in the future because of the high cost of the transportation of a large amount of red mud from alumina refineries to the point of application.

Pursuing green growth in technology firms through the connections between environmental innovation and sustainable business performance: Does service capability matter?

Abstract: In response to greater environmental awareness among stakeholders, companies have become increasingly interested in practices such as eco-innovation. Despite the expanding literature on eco-innovation, scholars have so far paid little attention to the study of eco-innovation and its impact on business sustainability, particularly considering the mediating effect of service innovation capability. To fill this research gap, this study extends the concepts of green business by investigating an original conceptual framework, which proposes that the capacity for service innovation has a mediating effect on the relationship between sustainable organizational performance and environmental innovation. This conceptual framework is subjected to empirical testing, implemented through a survey involving 95 Malaysian firms which use green technology. Data is collected through both postal and online questionnaires and analyzed through structural equation modeling using partial least squares. Respondents for this paper were identified using the directories of MyHijau (2013) and the Malaysia External Trade Development Corporation, 2014. The results suggest that: (1) eco-innovations unlock better sustainable performance; (2) service innovation capability has a partially significant positive mediating effect; (3) service innovation capability ultimately benefits companies by allowing them to differentiate through an emphasis on value creation; (4) service capability can also act as a business strategy to create barriers to new entry by competitors. Thus, eco-innovation and service innovation capability tend to represent significant intangible resources and enable an organization to achieve long-term objectives, competitive advantage and business sustainability. To date, this is the first study relating eco-innovation, service innovation capability and sustainability performance in the Malaysian corporate context and using a specific sample of companies that make use of green technologies. © 2018 Elsevier B.V.

Green innovation and firm performance: Evidence from listed companies in China

Abstract: This paper focuses on how green patenting influences a firm’s subsequent performance. By investigating listed manufacturing firms in China for the 2000–2010 period, we find a positive and significant relationship between green patenting and firm performance. Moreover, our research reveals that green growth is mainly driven by green utility-model patents and that this positive relationship only exists among state-owned enterprises (SOEs), which are more capable of leveraging green innovation through their close relationship with the government. Furthermore, the positive relationship is found to exist primarily after 2006, when the government began to provide formal legislative support to green industry.

What influences an individual’s pro-environmental behavior? A literature review

Abstract: This review paper discusses determinants of pro-environmental behavior on Resources Conservation and Recycling from 1987 to 2017. The main factors which influence pro-environmental behavior include both external and internal factors—specifically, demographic variables and psychological factors. The main purpose of this work is to review the literature (i.e., published studies) regarding the impact, relations, and mutual effects on pro-environmental behavior of each group of factors. Identifying the determinants of pro-environmental behavior is helpful when formulating the most appropriate and effective policies for improving the public’s behavior toward protecting the natural environment.

Understanding consumers’ behavior intentions towards dealing with the plastic waste: Perspective of a developing country

Abstract: Plastic consumption has been increasing globally, creating large amount of litter and posing threat to the environment. The recycling of the plastic waste can help in reducing it and its environmental threat. The purpose of this paper is to identify the factors that influence the consumer’s return/recycling intention regarding plastic waste. Moreover, recycling behavior of consumer was explored in detail. The theory of planned behavior was adapted and extended to measure the determinants of recycling behavior. Survey research design was employed whereas data includes valid 243 households, collected through survey questionnaire, by employing purposive sampling. PLS-SEM was applied on the collected data for hypotheses testing. The finding of this study indicates that subjective norms, awareness consequences and convenience are major predictors of return/recycling intention. Whereas, hypothesis for the attitude, perceived behavioral control and moral norms were rejected and they all have insignificant impact on return/recycling intention. Moreover, return intention have positive significant impact on resell, reuse, dispose and donate. Reuse was the most predicted by the return intention. This study enriches the literature of reverse logistics helping to understand the consumers’ perspective. Provides the insights that will help government and organizations to understand consumers’ return/recycling intention and formulate such strategies that will increase the involvement of consumers in recycling activities.

Recovery of precious metals from electronic waste and spent catalysts: A review

Abstract: Precious metals are widely applied in many industry fields due to their excellent corrosion resistance, good electrical conductivity and high catalytic activity. However, the reserves of precious metals falls short of the production globally. The rapid generation of end-of-life products has become the significant resources of precious metals. Among these products, electronic waste (e-waste) and spent catalysts are more concentrated since they account for over 90% of precious metals in industry. This article provides an overview of various technologies on the recovery of precious metals from e-waste and spent catalysts. It shows that recycling technologies have been significantly improved in recent years. The recycling processes have transferred from leaching by aqua regia, cyanide and chlorine in acid solution to less pollution agents leaching. Environment-oriented technologies have been raised great attention in precious metals recycling. The advantages and environmental impacts of these recycling technologies have been discussed in detail. However, there are still some challenges for future promotion. In order to achieve the environment-friendly and sustainable recycling for precious metals with high recovery rate, several considerations have been proposed.

Food waste to biochars through pyrolysis: A review

Abstract: Waste generated from anthropogenic activities contributes toward stresses on our natural systems through impacts associated with both production and disposal. Sustainable waste management necessitates that industries shift from the current linear model to a circular based economy, utilizing wastes as raw materials for the production of new products, eg. fuels and chemicals. Biomass and associated waste materials can be converted into value-added products using thermochemical processes. The pyrolysis process is a convenient thermochemical method, whereby biomass is efficiently converted into biofuels, biochars and BBQ briquettes; and further processing yields additional value added products, such as activated carbons, carbon black and printing ink. This paper reviews current development work and evaluates potential opportunities for food waste pyrolysis focusing on the conversion of food waste to biochar products. Overall, it was found that the constituents of the food waste together with the process conditions play a major role in the yield and composition of the produced chars. Moreover, more research work needs to be conducted on food waste to biochar and on mixed food blends in particular.

Sustainable use of Hermetia illucens insect biomass for feed and food: Attributional and consequential life cycle assessment

Abstract: The lack of protein sources in several parts of the world is triggering the search for locally produced and sustainable alternatives. Insect production is recognized as a potential solution. This study is a life cycle assessment (LCA) of food industry side streams transformation via Hermetia illucens into intermediate products applicable for feed and food purposes. It relies on attributional modelling for the estimation of the most impacting stages of insect production and on consequential modelling for the estimation of potential benefits or risks for the agri-food system. The consequential LCA included effects on the market, associated with upstream increase in feed (increase in commercial feed production) or downstream availability of insect product (substitution of fertilizer, protein concentrate for feed or chicken meat). Attributional and consequential LCAs are followed by sensitivity analyses, which identify the most promising directions towards sustainable insect production and estimate the magnitude of impact reductions if those directions are pursued by the industry. Analyses of the existing pilot process largely correspond with other findings in the literature, indicating fresh insect biomass is almost twice more sustainable than fresh chicken meat. Produced at pilot scale, protein concentrate (insect meal) while being competitive against animal-derived (whey, egg protein, fishmeal) and microalgae, has higher environmental impacts than plant-based meals. Further scenarios illustrate strategies for more sustainable use of environmental resources providing guidance for producers and funding agencies to direct the industry to an impact profile that is lower, than many existing protein sources.

Utilization of red mud in road base and subgrade materials: A review

Abstract: Red mud is highly alkaline slurry produced during alumina extraction from bauxite. Its disposal generates serious environmental pollution. The best way to solve red mud disposal issues is to develop economic utilization technologies that consume significant amounts of red mud. This paper reviews the possibility of utilizing red mud as a road base material, weak subgrade soil stabilizer as well as a subgrade material. Results showed that red mud can be used for those purposes. It was also found that the stabilizing content needed to meet a certain standard differs due to differences in requirements from one country to another. Therefore, there is a need to design proportions with UCS, CBR, leaching characteristics required by the country in which red mud is intended for use. The effect of various stabilizers on performance of red mud is discussed and it transpired that lime showed the best performance followed by dolime fine, ground granulated blast furnace slag, cement kiln dust and fly ash. Findings indicated that red mud shows better performance as a subgrade material than natural soil. Also the synergistic use of red mud and other wastes also improves the mechanical and durability properties of the material compared with using red mud alone. Based on mechanical, economic and environmental benefits, it is recommended to use red mud in road base structure rather than in subgrade despite higher red mud consumption in subgrade than in road base. The scope for future research in this area is also suggested.

Quantification of food waste per product group along the food supply chain in the European Union: a mass flow analysis

Abstract: In 2015, the United Nations defined the Sustainable Development Goals (SDG), which include a target (12.3) on food waste. The target requires "by 2030, to halve per capita global food waste at the retail and consumer levels and to reduce food losses along production and supply chains, including post-harvest losses". The target has increased awareness about the food waste problem and boosted research in food waste quantification. Nevertheless, there is a lack of studies that adopt a systematic approach to account for food waste providing disaggregated values per food supply chain stage and per food groups. Such an approach could support policy makers in prioritizing interventions for food waste reduction. To fill this gap, this paper presents a high-level top-down approach to food waste accounting in the European Union. The study aims to support the understanding of the mass flows associated with food production, consumption, and waste, addressing different food groups along the food supply chain. The method for accountin is the mass flow analysis. According to the results, cereals, fruit, and vegetables as the food groups are responsible for the highest amount of food waste, and the consumption stage to be responsible for the largest share of food waste for most food groups. This work highlights the need for further primary research on food waste generation in the EU. Ultimately, this would allow to robustly estimate the food waste generated at EU level, and establishing a more accurate baseline to track the progress towards SDG target 12.3.

On the importance of sustainable human resource management for the adoption of sustainable development goals

Abstract: Today, firms are becoming increasingly aware of the importance of social, ethical, and ecological objectives. In addition to financial profit, organizations are setting themselves new goals, focusing on individual, communal, and environmental-friendly performance and development. One of the disciplines that is promoting “green” organizations is Sustainable Human Resource Management (SHRM). Sustainable development goals (SDGs) are achieved through the adoption of new ecological techniques by the organization’s human capital and by the integration of innovative sustainable strategies. This systematic literature review examines the key role of SHRM in developing a sustainable work environment and in facilitating the attainment of SDGs. Based on a selection of empirical and conceptual articles, this review identifies the antecedents and outcomes of SHRM and highlights the obstacles to sustainable implementation not only at the level of the firm, but also from an international perspective. Four propositions are formulated that might be empirically tested in future studies. Research gaps in the existing literature are identified and potential future directions are suggested for further research in the field of sustainable management.

The process of peak CO2 emissions in developed economies: A perspective of industrialization and urbanization

Abstract: The experiences of peak carbon emissions in developed economies can provide a significant reference for other economies. In terms of peak carbon intensity, per capita carbon emissions and carbon emissions, the peak process in developed economies is divided into three stages. This study analyzes gross domestic product (GDP), per capita GDP, industrialization rate, urbanization rate, and other indicators in each stage. The impacts of urbanization and industrialization on carbon emissions are examined by using a threshold regression model. The results indicate that urbanization and income level have a significant double-threshold effect on carbon emissions. From the perspective of urbanization, there is no significant correlation between carbon emissions and urbanization in the low-urbanization stage. However, urbanization has a negative effect on carbon emissions in the mid-urbanization stage. Then, this inhibitory effect becomes a promotional effect when the urbanization level crosses the second threshold. From the perspective of income level, industrialization contributes to the growth of carbon emissions. The promotional effect of industrialization on carbon emissions gradually increases in the low and intermediate income levels. However, this promotional effect begins to weaken in the high income level. Our study not only extends the existing literature about peak carbon emissions, but also merits particular attention for policy makers in less developed economies.

Mapping Industrial Symbiosis Development in Europe_ typologies of networks, characteristics, performance and contribution to the Circular Economy

Abstract: Last years have seen a surge of Industrial Symbiosis (IS) development in association with ad-hoc widespread policies to encourage more circular and sustainable practices in the manufacturing sector. Developments in Europe, despite having attracted less attention in the literature, have been significant, driven both by public and private initiative. This paper provides an updated overview of IS activity in Europe, with a mapping of key networks, and a study of prevailing typologies of networks, size, geographical distribution and main streams/ resources traded. The analysis is based on a combination of desk research, gathering of primary data from case studies, a survey to IS network facilitators (n = 22) and in-depth interviews and focus groups (3) with IS practitioners, policy officers and industry representatives (n = 25). The analysis identified pockets of IS activity across all Europe, although varying in nature, resources exchanged and scale and scope of the initiatives. The average size of the mapped networks is approx. 473 members, but the median is approx. 100 members, which indicates high variability of sizes. The geographical scope of the synergies also seems to be dependent upon the following factors: 1) the type of waste stream/by-product; 2) transport costs and 3) market value of secondary materials. Types of waste streams exchanged common to most networks, are chemicals (e.g. chemical base products), biomass and agriculture by-products, wood and wood pellets, plastics, reusable construction materials, equipment, inert waste and water (different qualities including industrial water), residual heat and steam. The paper also discusses key obstacles facing IS development in Europe highlighting: 1) weakness of economic incentives given the low margin of IS projects associated to undeveloped secondary markets; 2) geographical variation of incentives and drivers, given differences in policy frameworks and support mechanisms (e.g. landfill tax levels) and 3) legislative issues that make transport over geographic boundaries extremely complex and administratively burdensome. Finally, the paper concludes with a general discussion of the potential of IS to contribute to the transition to the circular economy (CE) in Europe and identifies some key areas of future research.

Science Mapping Approach to Assisting the Review of Construction and Demolition Waste Management Research Published between 2009 and 2018

Abstract: Sustainable treatments of construction and demolition (C&D) wastes have become an increasingly urgent social, environmental, and economic issue worldwide. Based on a filter of 370 articles related to C&D waste management, this review-based study adopted a science mapping approach to evaluating the recent decade’s C&D waste management research. Through a three-step workflow consisting of bibliometric literature search, scientometric analysis, and qualitative discussion, this study identified the most influential journals, scholars, articles, and countries that have been active and influential in the C&D waste management research since 2009. Keyword analysis revealed the emerging research topics, such as BIM, prefabricated construction, Big Data, and Circular Economy. The follow-up discussion summarized the mainstream research areas (e.g., qualification of waste generation), discussed research gaps (e.g., integration of BIM and Big Data into C&D waste management), and proposed the framework for near-future research, such as a comprehensive evaluation of the performance of C&D waste diversion, human factors, and design and planning for waste diversion. By providing the big picture of the latest research in C&D waste management since 2009, the paper serves as a multi-disciplinary guide for practitioners and researchers to link current research areas into future trends.

Effect of Chinese policies on rare earth supply chain resilience

Abstract: Rare earths elements (REE) are considered as strategic resources because they interact with business and governments’ direct policy interventions. Policy interventions can have a major effect on security of rare earth supply (Kooroshy et al., 2015). The purpose of this study is to scrutinize China’s REE policies and its impacts on the supply chain resilience. We analyze the supply chain dynamics by specifically targeting a number of Chinese REE policies that have disruptive tendencies. We analyze various policies placing the price at the center as an overarching feedback loop. In other words, we focus on how price responds to various resilience influencing mechanisms such as diversity of supply, regulatory frameworks, and stockpiling. In the process, we investigate Chinese influence on rest of the world (RoW) supply chain and dynamics inside the Chinese supply chain as there are two different layers of supply chain one for China and another one for rest of the world. We show that the supply chain is a complex phenomenon and resilience of a system is not solely dependent on physical disruptions but also on dynamic factors such as societal and geo-political (eg. environmental regulation, speculative market and export ban). We identify links and interdependencies even where data is not readily available and examine how the overall system reacts to various constraints and disruptions.

Food-energy-water (FEW) nexus for urban sustainability: A comprehensive review

Abstract: The emerging popularity of the nexus discussion reflects the ongoing transition from a sectoral or silo approach to an integrative approach to address the global challenges pertinent to the three essential resources: food, energy, and water (FEW). Cities are critically important for advancing regional sustainable development and are thus placed at the center of the FEW nexus. This paper provides a comprehensive literature review to debate the current concepts and methods of the FEW nexus at different scales, with the aim of developing a conceptual knowledgebase framework for scientific analysis and policy making associated with the urban FEW nexus. Although the concept of nexus thinking has been widely accepted, a consistent and explicit cognition of the FEW nexus is still lacking, and a sophisticated methodological modeling framework is urgently required at various scales. As such, we proposed a three-dimensional conceptual framework of the urban FEW nexus from the perspective of resource interdependency, resource provision and system integration. This framework is useful in steering the systematic modeling and integrative management of the complex nexus issues of urban systems with different perspectives. Finally, the future directions of urban nexus research are identified from four aspects, including systematic characterization, cross-region tele-connection mechanisms, co-decision model development, and governance transition.

Environmental behavior in a private-sphere context: Integrating theories of planned behavior and value belief norm, self-identity and habit

Abstract: This study explores the determinants of environmental behavior in a private-sphere context and proposes an integrative model that includes the constructs from two theoretical frameworks, the theory of planned behavior (TPB) and the value belief norm theory (VBN), along with two additional variables, habits and self-identity. A questionnaire survey method was used to collect the survey data and statistical analysis relied on application of structural equation modeling (SEM). The results show that intention is the best predictor of environmental behavior followed by habits and subjective norm is the main attendant of intention. Awareness of consequences has a positive impact on personal and subjective norms, attitudes and perceived behavioral control, while these constructs have in turn a significant influence on behavioral intention. Self-identity moderates the relationships between biospheric values and personal norm, attitudes, subjective norm, and perceived behavioral control. The proposed model exhibit superior predictive ability compared to the original TPB and VBN models verifying its utility and effectiveness in explaining environmental behavior. The results of this work can be used by governments and policymakers to design and implement conservation programs to promote a more sustainable lifestyle. Recommendations for future research are discussed in the last section of this paper.

Exploring young adults’ e-waste recycling behaviour using an extended theory of planned behaviour model: A cross-cultural study

Abstract: The objective of this research is to explore young adults’ e-waste recycling behaviour cross-culturally using an extended Theory of planned Behaviour (TPB) model. The results of a survey involving respondents from the two culturally-distinct emerging markets showed that the key influencing factors that influenced e-waste recycling behaviour amongst young adults were: Attitude (moderated by a Sense of Duty), Perceived Control, Subjective Norm and Individual Responsibility whereas Convenience and Consequences Awareness constructs did not have significant influence. Cross-cultural differences were also evident as stronger relationships were witnessed for Perceived Control and Subjective Norm constructs for the Chinese young adults’ intention to recycle e-waste. The reverse was found to be true for Attitude (moderated by a Sense of Duty) and Individual Responsibility constructs where stronger relationships were observed in the Indian sample. This research makes a valuable theoretical contribution as it is positioned at the intersection of cross-cultural studies, sustainability and reverse supply chain management areas. This study has practical implication at two levels: the individual actor level and the supply chain level as consumers’ intentions to recycle, underpinned by responsibility towards environment, directly impact the performance of reverse supply chains.

Investigation on decision-making mechanism of residents’ household solid waste classification and recycling behaviors

Abstract: Residents’ participation in classification and recycling of urban household solid waste (HSW) is a critical factor for the success of municipal solid waste management. The aim of this study is to investigate the decision-making mechanism of residents’ HSW disposal behaviors by merging the theory of planned behavior and the Attitude-Behavior-Condition theory. In this study, based on the survey data of 709 residents in Suzhou, China and structural equation modeling method, the main factors that affect residents’ HSW disposal behaviors and their degree of influence were analyzed, followed by discussion on decision-making mechanisms. The findings show that residents’ behavioral selection has been significantly related to four intrinsic subjective factors and seven external objective factors, and the combined effect of the latter ones is nearly twice of that of the former ones. Moreover, the convenient of environmental facilities and services are most effective at promoting residents’ participation in HSW classification and recycling. Specifically, the observed variables of publicity and education, accessibility to recycling facilities, accessibility to classification facilities, willingness to participation of classification and residents' environmental awareness are the five most significant factors. The impact of laws and regulations is not significant; however, this may be because that there was no mandatory laws, regulations and incentive mechanisms on HSW classification and recycling in Suzhou in this period, and there is still a big gap and room for improvement in this aspect in mainland China. Finally, the study put forward relevant policy recommendations for the comprehensive management of urban HSW classification and recycling.

LCA of plastic waste recovery into recycled materials, energy and fuels in Singapore

Abstract: In Singapore, 822,200 tonnes of plastic waste was generated in 2016, with only 7% recycled. Due to the complex nature of plastic waste mixtures, mechanical recycling is often inefficient, leading to a majority of waste being incinerated. In this article, alternative solutions are introduced to address the waste problem, such as recovering valuable fuels from plastics via thermochemical methods. Life cycle assessment (LCA) was adopted to investigate 8 scenarios of plastic waste management options. In a nation with land scarcity, the scales and sizes of each plastic waste recycling/recovery method is also taken into consideration. The results demonstrated how different combinations of four plastics valorization technologies, and associated capacities, affected the potential environmental benefits and drawbacks of plastic waste treatment systems. In order to enable selecting the best option among the 8 scenarios, normalization and weighting was carried out.

Total material requirement for the global energy transition to 2050: A focus on transport and electricity

Abstract: Global energy transitions could fundamentally change flows of both minerals and energy resources over time. It is, therefore, increasingly important to holistically and dynamically capture the impacts of large-scale energy transitions on resource flows including hidden flows such as mine waste, as well as direct flows. Here we demonstrate a systematic model that can quantify resource flows of both minerals and energy resources under the energy transition by using stock-flow dynamics and the concept of Total Material Requirement (TMR). The proposed model was applied to the International Energy Agency’s scenarios up to 2050, targeting 15 electricity generation and 5 transport technologies. Results indicate that the global energy transition could increase TMR flows associated with mineral production by around 200–900% in the electricity sector and 350–700% in the transport sector respectively from 2015 to 2050, depending on the scenarios. Such a drastic increase in TMR flows is largely associated with an increased demand for copper, silver, nickel, lithium and cobalt, as well as steel. Our results highlight that the decarbonization of the electricity sector can reduce energy resource flows and support the hypothesis that the expansion of low-carbon technologies could reduce total resource flows expressed as TMR. In the transport sector, on the other hand, the dissemination of Electric Vehicles could cause a sharp increase in TMR flows associated with mineral production, which could offset a decrease in energy resource flows. Findings in this study emphasize that a sustainable transition would be unachievable without designing resource cycles with a nexus approach.

Coupling material circularity indicators and life cycle based indicators: A proposal to advance the assessment of circular economy strategies at the product level

Abstract: The debate on the identification of the most suited metrics for circular economy (CE) is open, no consensus has been reached yet on what CE indicators at product level should measure, which creates a subjective methodological framework for assessing CE strategies. In this study, we demonstrate that by coupling different types of indicators via Multi Criteria Decision Analysis (MCDA) it is possible to deal with conflicting situations where the selection of the best alternative can be biased by the choice of the metric. We use a beer packaging case, by simulating a situation where a company is interested in comparing the performances of different packaging from a CE perspective. We consider eight different beer packaging alternatives in two geographical contexts (United Kingdom and India). Two sets of indicators are coupled via MCDA: i) material circularity based- indicators, namely Material Reutilization Score and Material Circularity Indicator, and ii) a selection of life cycle based- indicators relevant for beer, i.e. climate change, abiotic resource depletion, acidification, particulate matter and water consumption. The results obtained by the application of the TOPSIS (Technique for Order by Similarity to Ideal Solution) method show that the different sets of indicators can be integrated and conflicts among them can be resolved. Overall, the application of different weighting scenarios does not change the ranking of the alternatives, thus confirming that the results are stable. Therefore, our proposal of coupling material circularity indicators with LCA indicators via MCDA can advance the assessment of CE strategies at the product level.

Young people’s behaviour intentions towards reducing PM2.5 in China: Extending the theory of planned behaviour

Abstract: Fine particulate matter (PM2.5) emissions have attracted extensive attention because of their severe negative impacts on human health and the national economy. Promoting public participation in reducing PM2.5, especially among young people, is one effective manner in which to control PM2.5 emissions. The present study explores the determinants that influence young people’s behavioural intentions towards reducing PM2.5 using an extended version of the theory of planned behaviour (TPB), which incorporates personal moral norms. Additionally, this paper evaluates and compares the direct and indirect relationships between subjective norms and PM2.5 reduction intentions. This study was tested empirically using survey data collected from 425 respondents in China. The results revealed that young people’s attitude towards reducing PM2.5, the subjective norm, was that behavioural control and personal moral norms significantly affect PM2.5 reduction intentions. Furthermore, the indirect effects of subjective norms on PM2.5 reduction intentions via other determinants were 2.5 times greater than the direct effect. In addition, the results also validated the appropriateness of the extended theory of planned behaviour for exploring young people’s PM2.5 reduction intention. Based on the results, implications and future research directions are also discussed.

Global environmental losses of plastics across their value chains

Abstract: With the increasing focus on marine plastic pollution, quantification of the environmental losses of plastics in the world, with differentiation into geographic regions, polymers and loss occurrences along the plastics value chains, is required. In this study, we make a global estimation of the losses of plastics to the environment across the entire plastic value chain, using existing literature and databases coupled with improved and additional methodological modelling of the losses. The resulting loss estimates are unprecedented in their detailed differentiations between polymers (23), plastic applications (13), geographical regions (11), and plastic value chain stages. Comprehensive sensitivity and uncertainty analyses were also conducted to identify key drivers in terms of plastic losses. We overall found that approximately 6.2 Mt (95% confidence interval, CI: 2.0–20.4 Mt) of macroplastics and 3.0 Mt (CI: 1.5–5.2 Mt) of microplastics were lost to the environment in 2015. The major macroplastic loss source was identified as the mismanaged municipal solid waste (MSW) management in low-income and lower-middle income countries (4.1 Mt). For microplastics, the major sources were abrasion of tyre rubbers, abrasion of road markings and plastics contributing to city dust generation. To curb marine plastic pollution, such quantified mapping as ours are needed to evaluate the magnitude of the plastics losses to environment from different sources and locations, and enable a further assessment of their environmental damage. Through our uncertainty and sensitivity analyses, we highlight plastics sources that should be prioritized in further research works to obtain a more comprehensive and accurate representation of global plastics losses.

An overview on the reuse of waste glasses in alkali-activated materials

Abstract: Alkali-activated materials (AAMs) have been attracting much attention worldwide owing to their excellent performances such as strong resistance to chemical corrosion and thermal properties, and the valorization of industrial waste materials. The reuse of waste glasses as aggregates, precursors and activators in the preparation of AAMs seems a feasible path of efficient utilization of solid waste and reducing the cost of AAMs. This paper comprehensively reviews researches on waste glasses reused in AAMs from three aspects is presented: reuse of waste glasses as aggregates, precursors and activators. The incorporation of waste glasses as fine aggregates can enhance the workability, thermal conductivity and capacity against sulfate attack of AAMs. The reuse of glass powders as precursors can generate acceptable strengths. Three methods, i.e. fusion, hydrothermal process and thermochemical process are applied to use waste glasses to manufacture alternative activators. However, the related research on the employment of waste glasses in AAMs is limited. For instance, the absence of assessment criteria on the reactivity of waste glasses, the potential ASR expansion of glass aggregates. More energy-efficient methods of synthesizing activators with waste glasses and investigation into the durability of AAMs with waste glasses are required in the future.

Circular building materials: Carbon saving potential and the role of business model innovation and public policy

Abstract: Buildings are responsible for a third of global greenhouse gas emissions, with much of their life cycle impacts stemming from embodied impacts of building materials. Both at EU and Member State level, circular economy and resource efficiency policies are promoting production of lower-impact building materials with secondary material input. However, secondary material strategies do not result in carbon saving by default, and depend on businesses developing effective and economic applications that can overcome the many barriers to closing material loops. This paper aims to advance understanding of the relevance of secondary material for decarbonisation of the building sector, as well as the interplay of business model innovation and policy instruments in this transition. We used a comparative case study of three pioneering Scandinavian companies that produce circular building materials to estimate the carbon saving potential of using secondary material. We also examined business model innovations to implement strategies, and companies’ experienced and desired policies to help remove barriers. The results show clearly that all three cases offer potential for carbon savings. As the savings vary significantly, findings suggest that careful consideration of affected processes and markets is a key to attaining carbon savings. Business model innovations to enable secondary material use involve establishing key partnerships to access secondary materials, developing recovery process and technology, targeting customer segments that value lower environmental impacts, and considering life cycle costs. Public policies that can help companies remove barriers include 1) incorporating reuse of higher material value in construction and demolition waste targets, and 2) incentivising waste collection and recovery markets to offer recovered material at higher value.