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[Display omitted] • SLF from WEEE can be transformed into a feedstock material for recycling. • base metals (Cu, Pb, Zn) and precious metals are concentrated in the solid product. • Continuous pyrolysis evidenced a substantial reduction of mass (50%) in the SLF. • Pyrolytic carbon from SLF can be used as reducing agent in the copper industry. • Continuous technology minimized oil production while maximizing permanent gas. The surge in Waste Electrical and Electronic Equipment (WEEE) generation, reaching 53.6 million metric tons (Mt) in 2019, demands efficient recycling solutions. This study focuses on the Shredder Light Fraction (SLF), a material stream derived from the mechanical pre-processing of WEEE, which is considered "municipal waste". SLF constitutes 4.2% of the output material and is rich in metals like copper, tin, lead, zinc, silver, and gold. Pyrolysis treatment was applied to SLF, enabling recyclability. Both batch and continuous setups were employed for materials flow analysis and technical evaluation of the resource potential. The research evaluates the impact of pyrolysis technology on solid fraction metal content and pyrolysis gas/oil energy potential. Scaling up the process addressed material heterogeneity and increased the reliability of the obtained results. An innovative pyrometallurgical extraction approach was suggested, to recover valuable metals in SLF which otherwise could be lost via energy recovery methods. The resulting solid product after pyrolysis showed enriched concentrations of copper, zinc, lead, and precious metals with concentrations acceptable for industrial use. Additionally, it displayed reduced mass and diminished hazardous constituents. The non-condensable gas, rich in hydrogen, carbon monoxide, and methane, exhibited potential as an alternative energy source or reducing agent in the metallurgical sector. This research advances metal recycling from SLF, offering valuable insights for environmental impact mitigation as waste was transformed into a valuable by-product for potential use in the copper industry. [ABSTRACT FROM AUTHOR]

[Display omitted] • Measurement of GEM emissions from urban atmosphere in Pakistan. • Open burning, and physical dismantling are common e-waste recycling practices. • E-waste sites from Karachi, Lahore, and Peshawar were found highly contaminated. • Lower seasonal variations indicating the stable emission sources throughout year. • Workers and public living close to these facilities are exposed to hazards of GEM. Detrimental effects of mercury (Hg) on ecosystems and human health have been well-documented. Whereas emissions of gaseous elemental mercury (GEM) from e-waste recycling have been reported in developed countries, much less is known about the situation in the Global South. Using a total of 132 passive air samplers, seasonally resolved concentrations of GEM in air were measured continuously at 32 informal e-waste recycling facilities and background location in Pakistan for a period of one year between September 2020 and December 2021. Annual average GEM concentrations at the studied locations ranged from 1.8 to 92 ng m−3. Among the studied cities, higher concentrations were measured in Karachi (mean ± s.d: 17 ± 22, range: 4.2–92 ng m−3), Lahore (16 ± 4.2, 8.2–22 ng m−3) and Peshawar (15 ± 17, 4.9–80 ng m−3), while lower levels were measured in Hyderabad (6.9 ± 6.2, 3.1–25 ng m−3), consistent with a higher rate of informal recycling activities in metropolitan areas. Seasonally, higher GEM levels occurred during autumn (15 ± 16: 3.3–92 ng m−3) and summer (13 ± 8.7: 1.8–80 ng m−3) than in winter (12 ± 8.4: 2.5–49 ng m−3) and spring (9.2 ± 7.3: 1.8–80 ng m−3), possibly reflecting enhanced volatilization at higher temperatures and/or varying magnitude of recycling operations in different seasons. Policies and strict regulations related to e-waste management should be developed and implemented urgently in the country. [ABSTRACT FROM AUTHOR]

• Real-time object detection can be utilized to pre-separate EEEs. • Among 37 types of EEEs, 12 types of battery-powered EEE were sorted. • Image augmentation and transfer learning improved training and test efficiency. • YOLOv4-based backbone, precision rate showed ranging from 84.5% to 90.1%. With the growing use of electrical and electronic equipment (EEE), managing end-of-life EEE has become critical. Thus, the demand for sorting and detaching batteries from EEE in real time has increased. In this study, we investigated real-time object detection for sorting EEE, which using batteries, among numerous EEEs. To select products with batteries that have been mainly recycled, we crowd-sourced and gathered about 23,000 image datasets of the EEE with battery. Two learning techniques—data augmentation and transfer learning—were applied to resolve the limitations of the real-world data. We conducted YOLOv4-based experiments on the backbone and the resolution. Moreover, we defined this task as a binary classification problem; therefore, we recalculated the average precision (AP) scores from the network through postprocessing. We achieved battery-powered EEE detection scores of 90.1% and 84.5% at AP scores of 0.50 and 0.50–0.95, respectively. The results showed that this approach can provide practical and accurate information in the real world, hence encouraging the use of deep learning in the pre-sorting stage of the battery-powered EEE recycling industry. [ABSTRACT FROM AUTHOR]

• Electronic recycling exposes workers to toxic metals, e.g. lead, cadmium and nickel. • Metals and dust concentrations are associated with the volume of materials treated. • Dismantling of cathode ray tubes generates more lead and yttrium than other devices. • Exposures to metal mixtures increase risk of renal and nervous system disorders. • Occupational health & safety practices are inadequate in most facilities. Electronic waste recycling (e-recycling) involves manual operations that expose workers to toxic metals. We aim to describe occupational health and safety practices and workers' exposures to metals in the Canadian formal e-recycling industry, and to estimate the health risk associated with multiple exposures. This cross-sectional study documented practices through observations and questionnaires, and assessed metal exposures using personal air samples and biomarkers. Health risks were estimated relative to recognised occupational exposure guidelines, and using an additive approach for consideration of multiple exposures. Six e-recycling and one commercial recycling facilities were investigated, and the metal exposures of 99 workers (23 women) were measured. In most facilities, dust control was inadequate and personal protective equipment was improperly worn. In e-recycling, lead was detected in all air samples and in most blood samples, up to 48 µg/m3 and 136 µg/l, respectively. Other quantified metals included beryllium, mercury, arsenic, barium, cadmium, chrome, cobalt, copper, indium, manganese, nickel and yttrium. When handling cathode ray tube screens, workers were 4.9 times and 8.5 times more likely to be exposed to lead and yttrium, respectively, than workers who were not assigned to a specific type of electronics. Overall, exposures were largely associated with facility size and airborne dust concentration. The additive hazard indices for airborne exposures raised concerns for kidney disorders, for peripheral and central nervous systems, and for the male reproductive system. Minimizing airborne dust through collective control methods and adequately using personal protection should reduce metal exposures and associated health risks in this growing industry. [ABSTRACT FROM AUTHOR]

• Systems for recycling e-waste are not working in many countries. • Governance constructed by local actors shows better results. • Data sustain the local constructed governance as a way to manage recycling chain. • The matrix of local constructed governance indicators is operational. Electronic waste is an environmental problem because its production volume exceeds its recycling capacity. Academic and managerial production affirm two reasons: (a) dominant market logic and; (b) unresolved asymmetries among actors, causing conflicts to work together. Following the qualitative methodology, we investigate the e-waste situation in São Paulo City. The results allow us to propose that governance constructed by local actors could be a thoughtful way to promote e-waste recycling. Examples from around the world sustain this proposition. The theoretical principle is that the social process of constructing the mechanisms for collective action can solve challenges because the rules, roles, and actions are discussed and assumed by the actors working together. We present a matrix of indicators to be used in future studies in order to refine the proposition of constructed governance. [ABSTRACT FROM AUTHOR]

[Display omitted] • An eco-efficient tantalum recovery process from e-waste has been developed. • Two different competitive feasible routes for extraction of tantalum are purposed. • Quantitative extraction of tantalum without using HF has been archived. • Calcination, HF substitute lixiviant are two important components for recovery. • The mechanism involved in calcination-assisted oxidation has been explored. Global tantalum production from mines averages 1800 tons per year and hardly increases, but demand for tantalum in the electronics industry consistently increasing. Globally, 50% of total tantalum produced is being used for tantalum capacitors manufacturing, almost all demand from various industries is mainly met by primary resources only. Tantalum production and supply predominantly dominated by Congo and Rwanda which accounts for > 50%, add disadvantages for the strategic and economic competitiveness of other nations. To address the monopoly dominated by Congo and Rwanda, and the disparity of tantalum primary reserve, exploitation of secondary resources can alternatively address the drawbacks of primary resource distribution. Currently, hardly < 1% of tantalum getting recycled, and the poor recycling rate of tantalum is mainly contributed by the lack of efficient and sustainable valorization technology for recycling tantalum-bearing scraps like electronic capacitors and semiconductor industry tantalum scrap. In the current investigation, a sustainable tantalum extraction process from scrap dominated by hydrometallurgical route has been developed. Tantalum scrap which is passive to leach for tantalum recovery was calcinated for oxidation of TaN content and followed by tantalum has been leached using a mixture of NaF and HCl, a specially developed novel lixiviant for the purpose as an HF substituent. Calcination process parameter like temperature and time requirement for oxidation was optimized varying one parameter at a time. Then, the efficient leaching condition was optimized for quantitative leaching of tantalum. The process can achieve 99.99% efficient leaching, the process can successfully be applied for feasible industrial-scale tantalum scrap recycling. The HF substituent lixiviant can add advantages to overcome occupational and industrial operation safety challenges associated with HF lixiviant. The reported valorization process can be a sustainable tantalum recycling process that simultaneously can address UNO sustainable development goal, WEEE directive, and UNEP E-Waste Management goal. [ABSTRACT FROM AUTHOR]

• A multi-data source-based hybrid methodology was developed. • A novel seasonal grey model considering seasonal trend trait was proposed. • The recycling value of wasted DESWH from 2012Q1 to 2038Q4 was analysed. A domestic electrical storage water heater (i.e., DESWH) is one of the 14 products listed in China's Waste Electrical and Electronic Products Disposal Catalogue (Batch 2). Due to the lack of systematic quantitative analysis on the waste quantity and recovery value of a DESWH, a multi-data source-based hybrid methodology based on quarterly sales data, survey data and internet data is proposed. In the methodology, the seasonal Mann-Kendall trend test is used to identify the seasonal trait of the quarterly sales data for DESWHs, and an accurate prediction of the sales volume of DESWHs is obtained via a generalised seasonal grey model with dynamic seasonal adjustment factors. Then the lifespan distribution of DESWHs is fitted based on the survey data, and the quantity of wasted DESWHs is estimated from 2012Q1 to 2038Q4. Finally, on the basis of the data crawled from the internet, the weight distribution of DESWHs is constructed, and the recycling value of wasted DESWHs is then calculated. The empirical results show that the waste quantity of DESWHs will increase greatly from 2012Q1 to 2022Q4 and that the recycling value of wasted DESWHs may be worth 18.48 billion yuan in China. The results show that the wasted DESWHs have a great recycling value, and that the proposed multi-data source based hybrid methodology can be used as an effective estimation method for the recycling value of electronic waste. [ABSTRACT FROM AUTHOR]

• This study models different formal channel structures under government subsidy. • The study considers both price insensitive/sensitive overall collection quantity. • It concludes the positive influence of the subsidy on the formal channel. • Deriving optimal subsidies from the aspect of minimizing informal channel's profit. • Exploring optimal formal channel structures for formal recyclers and the government. This study aims to analyze the influence of Chinese government subsidy on e-waste treatment formal and informal reverse supply chains (RSC) and to explore the optimal formal channel structure. Under the formal recycler-Stackelberg game, we establish three game theory models respectively under the conditions of price insensitive and price sensitive overall collection quantity. In each model, a dual-channel RSC, the green technology investment decision of formal recycler and a subsidy for formal recycler are modelled. Besides, the three models are different in collectors and collection effort implementers of the formal channel. Through mathematical modelling and comparison analysis, the study concludes that the best choice for the formal recycling enterprises is to establish its own collection channel or centralize other independent collection channels. Under the condition of price insensitive overall collection quantity, the suboptimal choice is to implement collection effort positively. Under the condition of price sensitive overall collection quantity, the suboptimal choice is to outsource the collection effort when formal recycling enterprises benefit more from the collection effort. And the phenomenon is more outstanding when the overall collection quantity can be greatly improved by the collection price. For governments, they are recommended to prudently implement the subsidy and determine the amount of subsidy because the subsidy may benefit informal channels and the effectiveness of the subsidy varies along with formal channel structures. This study is beneficial for the promotion of formal RSC by providing the optimal channel structure for formal recycling enterprises and indicating the optimal subsidy for governments. [ABSTRACT FROM AUTHOR]

• Key policies to promote the CDW recycling are quantitatively explored. • The stepwise regression was employed to evaluate the effect of the nine policies. • Green product label is the top policy followed by Charge and Tax and Technical Standard. • 84.6% of the sample cities employed the Charge and Tax. • The ratios were only 11.5% for Technical Standard and 7.7% for Green Product Label. There is a growing need to recycle construction and demolition waste (CDW) in order to treat the huge amount of CDW in many metropolises of China. However, the CDW recycling industry is still in its initial stage and developed unevenly across various areas of China. In spite of some qualitative discussions, the quantitative analysis of crucial policies to the development of CDW recycling industry was overlooked. Through literature review, nine influential policy instruments were identified in term of three categories, i.e. control and command policy, market-based policy and information-based policy. The stepwise regression analysis was employed to explore the relationships between the influential policies and the development level of CDW recycling industry in 52 sample Chinese cities. The results demonstrated that Green Product Label, Charge and Tax and Technical Standards had statistically significant association with the development of CDW recycling industry in sample cities. In the surveyed cities, Charge or Tax was the most common policy tool (84.6%), but Green Product Label (7.7%) and Technological standards (11.5%) were rather less frequently employed. According to the results, Green Product Label and Technical Standards should be given higher priority. In addition, landfill charge should be introduced as a fundamental impetus. These results provide directions for other cities to facilitate the development of their CDW recycling industry. [ABSTRACT FROM AUTHOR]

• Index of recycling sustainability for assessing waste paper recycling. • Integrating methodology of GIS and value chain model. • Historical changes of informal recyclables distribution sites in Beijing. • Value chain of waste paper recycling in Beijing may face challenges in the future. • Policy implications to improve waste paper recycling in Beijing. China established a self-organized and market-driven recycling system, which was dominated by the informal sectors. In recent years, the amount of domestically-recycled waste paper grew slower than expectation in China, which may be resulted from a decline in economic sustainability of current recycling system. For understanding the waste paper recycling system in most cities in China, the economic mechanism remains unclear and the city-level data is extremely insufficient. In this work, an index of recycling sustainability (IRS, benefit divided by cost) is analyzed with a resolution of 1 km2 grid in Beijing City, by adopting value chain and GIS methodology. Five degrees of IRS are defined, from high-degree (IRS > 1.10) to low-degree (IRS < 0.95). Different stakeholders in the informal waste paper recycling system were interviewed to fill the data gap. Results show that: (1) from 2015 to 2018, the informal recycling of waste paper accounted for approximate 80% in Beijing; (2) the number of informal recyclables distribution sites decreased from 27 to 11, and their average distance to the city-center rose from 27.5 km to 40.9 km; (3) in 2015 and 2018, the grids with high-degree IRS accounted for 99.5% and 89.2%, respectively, indicating a sustainable waste paper recycling industry in Beijing; and (4) according to the scenario analysis, if the operating cost rises by 30%, the grids with low-degree IRS accounts for 98.5%, indicating a nontrivial challenges when the recycling cost keeps increasing in the future. Policy recommendations are put forward for a more sustainable paper waste recycling system in China. [ABSTRACT FROM AUTHOR]

• Family size and level of education are weak drivers of separation intention. • The quality of council services is a moderator of separation intention. • Perceived behavioural control have no impact on attitude towards source separation. • Long distances to buyback centre is a deterrent. Waste recycling, in particular source separation contribute significantly to the extension of landfill life and the evolution of green communities. Factors that affect participation in source waste separation amongst Metropolitans Johannesburg residents was investigated by social survey using field questionnaire data to assess socio-demographic factors and was analysed by statistical tools and behavioural constructs i.e. attitudes, subjective norms, perceived behavioural control, intentions, and situational factors. The results revealed that for graduates, source separation was driven by social responsibilities and family size while council awareness campaign, financial incentives and provision of recycling facilities are the driving force for source separation amongst respondents with matric and lower formal education. Family size and level of education are correlated to attitude with low correlations. The weak correlation was due to the perception of quality of services provided by the council. Incentives are moderators of intention of source separation but distances to buyback centre have to be carefully selected in order not to be a deterrent. Waste management agencies should accommodate the level of formal education and different family size in the formulation of source separation program. [ABSTRACT FROM AUTHOR]

• Consumer behaviors are critical to managing and reducing e-waste. • Faculty, students, and staff at a Midwestern University surveyed regarding e-waste. • Cost, knowledge, and access to recycling affect consumers choice to recycle. • Increased consumer knowledge should be paired with free or low-cost e-waste recycling options. The United States lacks a set of unified electronic waste recycling laws, contributing in part to the observed low rate of e-waste recycling behaviors among consumers. Individual factors of consumers contributing to the low recycling rates are not well understood. The objective of this study was to evaluate consumer behaviors, including barriers, surrounding e-waste recycling at a large Midwestern university in the United States. A survey was administered to faculty, graduate students, undergraduate students, and staff to determine their personal recycling habits, knowledge, and beliefs. The results indicate that free access to disposal, lack of consumer knowledge about products and disposal sites, and access to a recycling facility within a reasonable distance are all important factors in consumer decisions. Policy-makers and waste management professionals should focus on promotion of e-waste recycling behaviors through increased access to free or low-cost recycling as well as through the creation of recycling incentives. [ABSTRACT FROM AUTHOR]

• Quantitative measurements of 56 metals in ten electronic devices or waste samples. • Wide range of elements in a single device: 48 metals in computer hard drives. • Potentially high economic value recovered from metals in electronic devices. • Disposal and handing regulations should consider toxic elements in some electronics. Over the past few decades, electronic devices of all kinds, and especially consumer electronics, have evolved in function and composition, in parallel to increasing manufacture and use. There is great potential for recovering economic value and reducing environmental impact by recycling devices and extracting various elements. However, there are few studies that comprehensively identify the elemental content of electronic devices or electronic waste. In the present study, consumer electronics and components (hard drives, ethernet hubs, portable media players, printers, answering machines, mobile phones, Digital Versatile Disc (DVD) players, computer wiring, and printed circuit boards) and electronic waste (low-grade scrap from one commercial recycling facility) were analyzed for rare earth, precious and critical metals. The overall procedure included size reduction, microwave assisted digestion, and Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) analysis. Fifty-six elements were quantified or detected in these devices: 14 rare earth elements, six platinum group metals, 20 critical metals, and 16 other elements, including some precious metals. A single device could include a wide range of elements: 48 metals were quantified in the computer hard drives. The estimated economic value of the metals in each device ranged from $12.94 USD (computer wiring) to $454 USD (hard drives). The variety of metals in electronic devices suggests that end-of-life management strategies should focus on recycling and recovery, which also decreases the overall environmental impacts of the devices, especially associated with mining and refining metals. [ABSTRACT FROM AUTHOR]

• The survey yielded meaningful primary data on electronics acquisition/use/disposal. • Fixing damaged items was common, but purchasing second-hand items was not. • More out-of-use electronics were stored in the home than had been disposed of. • Residents of São Paulo showed different patterns from those in the UK or Spain. • These findings can inform e-waste management policies in Brazil. Understanding the domestic flow of e-waste is essential for efficient waste management in urban contexts. However, diagnosis of domestic e-waste flow is complex due to its diffuse generation and dependence on consumer behavior. Here, we characterized domestic e-waste flow in São Paulo, Brazil (a megacity with roughly 11 million inhabitants in 3.5 million households), describing the stages of product acquisition, out-of-use storage, and end-of-life destination, via a population-based cross-sectional study using a statistically representative sample. We conducted household interviews using a structured questionnaire, with questions on characteristics, quantities, and behaviors of acquisition, replacement, storage, repair, and destination for 26 electric and electronic equipment (EEE) categories. Each household had on average 21 EEE (95% confidence interval [CI]: 19.7–21.7), of which 18 were in use and 3 were out-of-use. Out-of-use storage was common, occurring in 72.6% of households. Discarded EEE (i.e., e-waste) was destined for intended reuse (59.5%; 95% CI: 57.4–61.5%), recycling (20.4%; 95% CI: 18.8–22.1%), and, particularly for small EEE, municipal waste (16.0%; 95% CI: 14.5–17.6%). Other aspects of domestic e-waste flow (e.g., place and time of acquisition, second-hand acquisition, donation, intention to repair damaged EEE, and storage) were quantified and related to actions for public policies. This research shows that household surveys are useful for obtaining primary data to verify consumer behavior toward EEE. We expect the findings of this study to support decision-making for public policies related to e-waste management, particularly in countries where reverse logistics systems are in the initial phase of implementation. [ABSTRACT FROM AUTHOR]

• A household e-waste collection network model. • Optimizing the collection amount and total costs, including advertising cost. • An efficient metaheuristic to obtain the Pareto frontier. • A case study showing tradeoff between network construction and public awareness. • Insights for policy makers for the tradeoff between collection amount and cost. The rapid expansion of technology, coupled with the falling prices of electronic products and their fast obsolescence, has resulted in a rapidly-growing amount of e-waste worldwide. Because of adverse effects on environment and public health, more and more countries and regions have begun to establish and operate public e-waste collection systems. In many developing countries, the low level of environmental awareness and the existence of informal sectors present obstacles to the success of such collection systems. This paper proposes to design a household e-waste collection network and launch a corresponding public service advertising campaign to counteract the informal recycling markets. The proposed mixed integer nonlinear program maximizes the amount of collected e-waste and minimizes overall costs of developing the network and its advertising campaign. A decomposition-based, multi-objective metaheuristic was developed to obtain the Pareto frontier. A case study based on the e-waste collection system in Changsha, China contextualizes the problem and developed methodology. Experiment results show that the cost of network construction and public advertising must be carefully balanced for limited budgets. The impact of residents' environmental awareness is also important to the collection effect. From a methodology perspective, this paper uses the Pareto analysis approach to study the design of household e-waste collection networks, with a supporting public service announcement campaign, in the presence of informal recycling markets. This paper also offers a policy design decision support tool to help regulators determine most workable policies that will balance the trade-offs between the two objectives. [ABSTRACT FROM AUTHOR]

• Knowledge spillovers have a positive impact on environmental innovation. • We investigated the waste recycling innovation in the USA, Japan and Europe. • Policymakers should carefully favor industrial relatedness. Since natural resources are finite, new policy instruments to sustain the most efficient processes of waste recycling are required in all countries. To this end, it is critical to explore all technology mechanisms underlying solid waste researchers and practitioners' behaviors. The study focuses on to demonstrate the importance of knowledge diffusion between the source and destination of environmental innovations. This way, policymakers can elaborate opportune strategies to improve the efficiency of innovation activities. By analyzing a sample of 240 large international firms from the USA, Japan, and Europe, this paper discusses the extent to which innovation inputs, research and development, and relative technological spillovers affect environmental innovation—that is measured by the number of waste recycle and land fertilizers patents. The novelty of the study comes from introducing a knowledge production function approach to analyze the role of technological knowledge spillovers on waste recycling and land fertilizers efficiency at the firm level. The technological relatedness between the firms is computed through technological proximity, based on the construction of technological vectors for each firm. The results reveal a significant positive impact of external spillovers on firms' environmental innovation levels. This finding is important particularly in terms of policy implications concerning industrial strategies; as in order to improve environmental innovation, incentives that favor industrial relatedness and establishing integration between firms are crucial. [ABSTRACT FROM AUTHOR]

The thermal treatment of waste electrical and electronic equipment (WEEE) is regarded as the largest potential contributor to the environmental release of polybrominated dibenzo-p-dioxins/dibenzofurans (PBDD/Fs). Herein, the pyrolysis of decabromodiphenyl ether (deca-BDE), polyethylene (PE) and metal blends was conducted to investigate the emission characteristics of PBDD/Fs at different thermal treatment conditions. The total yield of polybrominated dibenzo-p-dioxins (PBDDs) was less than that of polybrominated dibenzofurans (PBDFs) during the pyrolysis of the PE matrix and metal blends. 2,3,7,8-TBDF and 1,2,3,7,8-PBDF were the dominant congeners emitted from the pyrolysis. Temperature, presence of oxygen and type of added metal were the critical influencing factors for the PBDD/F formation rates and speciation in the pyrolysis process. [ABSTRACT FROM AUTHOR]

An integral closed circuit hydrometallurgical process is presented for base metal recovery from electronic waste. The leaching medium consists of a sodium citrate solution, from which base metals are retrieved by direct electrowinning, and the barren solution is recycled back to the leaching stage. This leaching-electrowinning cycle was repeated four times. The redox properties of the fresh citrate solution, as well as the leach liquors, were characterized by cyclic voltammetry to determine adequate conditions for metal reduction, as well as to limit citrate degradation. The leaching efficiency of electronic waste, employing the same solution after four complete cycles was 71, 83 and 94% for copper, iron and lead, respectively, compared to the original leach with fresh citrate solution. [ABSTRACT FROM AUTHOR]

Waste Electrical and Electronic Equipment (WEEE) volume is increasing, worldwide. In 2011, the Chinese government issued new regulations on WEEE recycling and disposal, establishing a WEEE treatment subsidy funded by a levy on producers of electrical and electronic equipment. In order to evaluate WEEE recycling treatment costs and revenue possibilities under the new regulations, and to propose suggestions for cost-effective WEEE management, a comprehensive revenue-expenditure model (REM), were established for this study, including 7 types of costs, 4 types of fees, and one type of revenue. Since TV sets dominated the volume of WEEE treated from 2013 to 2014, with a contribution rate of 87.3%, TV sets were taken as a representative case. Results showed that the treatment cost varied from 46.4 RMB/unit to 82.5 RMB/unit, with a treatment quantity of 130,000 units to 1,200,000 units per year in China. Collection cost accounted for the largest portion (about 70.0%), while taxes and fees (about 11.0 %) and labor cost (about 7.0 %) contributed less. The average costs for disposal, sales, and taxes had no influence on treatment quantity (TQ). TQ might have an adverse effect on average labor and management costs; while average collection and purchase fees, and financing costs, would vary with purchase price, and the average sales fees and taxes would vary with the sales of dismantled materials and other recycled products. Recycling enterprises could reduce their costs by setting up online and offline collection platforms, cooperating with individual collectors, creating door-to-door collection channels, improving production efficiency and reducing administrative expenditures. The government could provide economic incentives—such as subsidies, low-cost loans, tax cuts and credits—and could also raise public awareness of waste management and environmental protection, in order to capture some of the WEEE currently discarded into the general waste stream. Foreign companies with advanced WEEE utilization technology could invest or participate in this area, producing profits for themselves while helping to develop and implement environmentally friendly and energy-saving technologies applicable to the Chinese market. [ABSTRACT FROM AUTHOR]

Cathode ray tubes (CRTs) contain numerous harmful substances with different functions. Lead is found in the funnel glass of CRTs. Improperly treated toxic lead may pose significant risks to human health and the environment. This paper reviews and summarizes existing technological processes on the recycling of lead from waste CRTs, including pyrometallurgy, hydrometallurgy, and product-regeneration. The present situation, advantages, and disadvantages of these techniques are described in detail. Generally, pyrometallurgy shows better practicability in recovery lead from waste CRT than hydrometallurgy and hydrometallurgy, in view of environmental impact, energy-consumption, product formats and safety and maturity of technology. Moreover, the gaps in the existing technologies were identified and recommendations for future research were provided. [ABSTRACT FROM AUTHOR]

Bioleaching of Au from mobile phone printed circuit boards (MPPCBs) was studied, using Bacillus megaterium which is a cyanogenic bacterium. To maximize Au extraction, initial pH, pulp density, and glycine concentration were optimized via response surface methodology (RSM). Bioleaching of Cu, an important inhibitor on Au recovery, was also examined. To maximize Au recovery, the optimal condition suggested by the models was initial pH of 10, pulp density of 8.13 g/l, and glycine concentration of 10 g/l. Under the optimal condition, approximately 72% of Cu and 65 g Au/ton MPPCBs, which is 7 times greater than the recovery from gold mines, was extracted. Cu elimination from the MPPCBs having a rich content of Au did not cause a significant effect on Au recovery. It was found that when the ratio of Cu to Au is high, Cu elimination can considerably improve Au recovery. B. megaterium could extract the total Au from PCBs containing 130 g Au/ton MPPCBs. [ABSTRACT FROM AUTHOR]

Life cycle assessment of the collection, transport and recycling of various types of waste electrical and electronic equipment (WEEE) in Norway shows that small amounts of critical materials (refrigerants, precious/trace metals) are vital for the overall environmental accounts of the value chains. High-quality recycling ensures that materials and energy are effectively recovered from WEEE. This recovery means that responsible waste handling confers net environmental benefits in terms of global warming potential (GWP), for all types of WEEE analysed. For refrigeration equipment, the potential reduction of GWP by high-quality recycling is so large as to be of national significance. For all waste types, the magnitude of the net benefit from recovering materials and energy exceeds the negative consequences of irresponsible disposal. One outcome of this may be widespread misunderstanding of the need for recycling. Furthermore, framing public communication on recycling in terms of avoiding negative consequences, as is essentially universal, may not convey an appropriate message. The issue is particularly important where the consumer regards products as relatively disposable and environmentally benign, and/or where the “null option” of retaining the product at end-of-life is especially prevalent. The paper highlights the implications of all these issues for policy-makers, waste collectors and recyclers, and consumers. [ABSTRACT FROM AUTHOR]

Considering indium scarcity, the end-of-life (EOL) LCD, which accounts for up to 90% of market share can be a feasible secondary resource upon successful recycling. In the preferred hydrometallurgical process of such critical metals, leaching is the essential primary and essential phase has been investigated. In this process, LCD was mechanically separated along with other parts from EOL TVs through a smartly engineered process developed at our institute, Institute for Advanced Engineering (IAE), the Republic of Korea. After removing plastics and metals from the LCD, it was mechanically shredded for size reduction. The mechanically shredded LCD waste was leached with HCl for recovery of indium. Possible leaching parameters such as; effect of acid concentration, pulp density, temperature and effect of oxidant H 2 O 2 concentration were investigated to identify the best conditions for indium extraction. Indium (76.16 × 10 −3 g/L) and tin (10.24 × 10 −3 g/L) leaching was achieved at their optimum condition, i.e. lixiviant of 5 M HCl, a pulp density of 500 g/L, temperature 75 °C, agitation speed of 400 rpm and time for 120 min. At optimum condition the glass, plastic and the valuable metal indium have completely been separated. From indium enriched leach liquor, indium can be purified and recovered through hydrometallurgy. [ABSTRACT FROM AUTHOR]

This paper reviews the existing and state of art knowledge for electronic waste (e-waste) recycling. Electrical and/or electronic devices which are unwanted, broken or discarded by their original users are known as e-waste. The main purpose of this article is to provide a comprehensive review of e-waste problem, strategies of e-waste management and various physical, chemical and metallurgical e-waste recycling processes, their advantages and disadvantages towards achieving a cleaner process of waste utilization, with special attention towards extraction of both metallic values and nonmetallic substances. The hazards arise from the presence of heavy metals Hg, Cd, Pb, etc., brominated flame retardants (BFRs) and other potentially harmful substances in e-waste. Due to the presence of these substances, e-waste is generally considered as hazardous waste and, if improperly managed, may pose significant human and environmental health risks. This review describes the potential hazards and economic opportunities of e-waste. Firstly, an overview of e-waste/printed circuit board (PCB) components is given. Current status and future perspectives of e-waste/PCB recycling are described. E-waste characterization, dismantling methods, liberation and classification processes are also covered. Manual selective dismantling after desoldering and metal-nonmetal liberation at −150 μm with two step crushing are seen to be the best techniques. After size reduction, mainly physical separation processes employing gravity, electrostatic, magnetic separators, froth floatation, etc. have been critically reviewed here for separation of metals and nonmetals, along with useful utilizations of the nonmetallic materials. The recovery of metals from e-waste material after physical separation through pyrometallurgical, hydrometallurgical or biohydrometallurgical routes is also discussed along with purification and refining. Suitable PCB recycling flowsheets for industrial applications are also given. It seems that hydrometallurgical route will be a key player in the base and precious metals recoveries from e-waste. E-waste recycling will be a very important sector in the near future from economic and environmental perspectives. Recycling technology aims to take today’s waste and turn it into conflict-free, sustainable polymetallic secondary resources (i.e. Urban Mining) for tomorrow. Recycling technology must ensure that e-waste is processed in an environmentally friendly manner, with high efficiency and lowered carbon footprint, at a fraction of the costs involved with setting multibillion dollar smelting facilities. Taking into consideration our depleting natural resources, this Urban Mining approach offers quite a few benefits. This results in increased energy efficiency and lowers demand for mining of new raw materials. [ABSTRACT FROM AUTHOR]

Gold recovery from electronic waste material with high copper content was investigated at ambient conditions. A chemical preliminary treatment was found necessary to remove the large quantities of copper before the precious metal can be extracted. For this purpose inorganic acids (HCl, HNO 3 and H 2 SO 4 ) and two organic substances EDTA and citrate, were tested. The effect of auxiliary oxidants such as air, ozone and peroxide hydroxide was studied. In pretreatments with peroxide and HCl or citrate, copper extractions greater than 90% were achieved. In the second leaching stage for gold recovery, the solid residue of the copper extraction was contacted with thiourea solutions, resulting in greater than 90% gold removal after only one hour of reaction. [ABSTRACT FROM AUTHOR]

Waste generated by the electrical and electronic devices is huge concern worldwide. With decreasing life cycle of most electronic devices and unavailability of the suitable recycling technologies it is expected to have huge electronic and electrical wastes to be generated in the coming years. The environmental threats caused by the disposal and incineration of electronic waste starting from the atmosphere to the aquatic and terrestrial living system have raised high alerts and concerns on the gases produced (dioxins, furans, polybrominated organic pollutants, and polycyclic aromatic hydrocarbons) by thermal treatments and can cause serious health problems if the flue gas cleaning systems are not developed and implemented. Apart from that there can be also dissolution of heavy metals released to the ground water from the landfill sites. As all these electronic and electrical waste do posses richness in the metal values it would be worth recovering the metal content and protect the environmental from the pollution. Cyanide leaching has been a successful technology worldwide for the recovery of precious metals (especially Au and Ag) from ores/concentrates/waste materials. Nevertheless, cyanide is always preferred over others because of its potential to deliver high recovery with a cheaper cost. Cyanidation process also increases the additional work of effluent treatment prior to disposal. Several non-cyanide leaching processes have been developed considering toxic nature and handling problems of cyanide with non-toxic lixiviants such as thiourea, thiosulphate, aqua regia and iodine. Therefore, several recycling technologies have been developed using cyanide or non-cyanide leaching methods to recover precious and valuable metals. [ABSTRACT FROM AUTHOR]

To clarify current collection rules of waste batteries in municipal waste management in Japan and to examine future challenges for hazardous substance control and safety, we reviewed collection rules of waste batteries in the Tokyo Metropolitan Area. We also conducted a field survey of waste batteries collected at various battery and small waste electric and electronic equipment (WEEE) collection sites in Tokyo. The different types of batteries are not collected in a uniform way in the Tokyo area, so consumers need to pay attention to the specific collection rules for each type of battery in each municipality. In areas where small WEEE recycling schemes are being operated after the enforcement of the Act on Promotion of Recycling of Small Waste Electrical and Electronic Equipment in Japan in 2013, consumers may be confused about the need for separating batteries from small WEEE (especially mobile phones). Our field survey of collected waste batteries indicated that 6–10% of zinc carbon and alkaline batteries discarded in Japan currently could be regarded as containing mercury. More than 26% of zinc carbon dry batteries currently being discarded may have a lead content above the labelling threshold of the EU Batteries Directive (2006/66/EC). In terms of safety, despite announcements by producers and municipalities about using insulation (tape) on waste batteries to prevent fires, only 2.0% of discarded cylindrical dry batteries were insulated. Our field study of small WEEE showed that batteries made up an average of 4.6% of the total collected small WEEE on a weight basis. Exchangeable batteries were used in almost all of mobile phones, digital cameras, radios, and remote controls, but the removal rate was as low as 22% for mobile phones. Given the safety issues and the rapid changes occurring with mobile phones or other types of small WEEE, discussion is needed among stakeholders to determine how to safely collect and recycle WEEE and waste batteries. [ABSTRACT FROM AUTHOR]

The Waste Electrical and Electronic Equipment (WEEE) or e-waste recycling sector has grown considerably in the last fifteen years due to the ever shorter life cycles of consumables and an increasingly restrictive policy context. Cathode Ray Tubes (CRTs) from used television and computer screens represent one of the main sources of e-waste. CRTs contain toxic materials such as lead, cadmium, barium, and fluorescent powders which can be released if recycling of CRTs is not appropriate. Exposure to these harmful substances was assessed in nine workshops where CRT screens are treated. Particulate exposure levels were measured using a gravimetric method and metals were analysed by plasma emission spectrometry. The maximum levels of worker exposure were 8.8 mg/m 3 , 1504.3 μg/m 3 , 434.9 μg/m 3 , 576.3 μg/m 3 and 2894.3 μg/m 3 respectively for inhalable dust, barium, cadmium, lead and yttrium. The maximum levels of airborne pollutants in static samples were 39.0 mg/m 3 , 848.2 μg/m 3 , 698.4 μg/m 3 , 549.3 μg/m 3 and 3437.9 μg/m 3 for inhalable dust, barium, cadmium, lead and yttrium. The most harmful operations were identified, and preventive measures for reducing the chemical risk associated with screen recycling were proposed. Workplace measurements were used to define recommendations for reducing the chemical risks in CRT screens recycling facilities and for promoting the design and development of “clean and safe” processes in emerging recycling channels. [ABSTRACT FROM AUTHOR]

Abstract: Cathode Ray Tube, CRT, waste glass recycling has plagued glass manufacturers, electronics recyclers and electronics waste policy makers for decades because the total supply of waste glass exceeds demand, and the formulations of CRT glass are ill suited for most reuse options. The solutions are to separate the undesirable components (e.g. lead oxide) in the waste and create demand for new products. Achieving this is no simple feat, however, as there are many obstacles: limited knowledge of waste glass composition; limited automation in the recycling process; transportation of recycled material; and a weak and underdeveloped market. Thus one of the main goals of this paper is to advise electronic glass recyclers on how to best manage a diverse supply of glass waste and successfully market to end users. Further, this paper offers future directions for academic and industry research. To develop the recommendations offered here, a combination of approaches were used: (1) a thorough study of historic trends in CRT glass chemistry; (2) bulk glass collection and analysis of cullet from a large-scale glass recycler; (3) conversations with industry members and a review of potential applications; and (4) evaluation of the economic viability of specific uses for recycled CRT glass. If academia and industry can solve these problems (for example by creating a database of composition organized by manufacturer and glass source) then the reuse of CRT glass can be increased. [Copyright &y& Elsevier]

Abstract: Mobile phones have relatively short lifecycles and are rapidly seen as obsolete by many users within little over a year. However, the reusability of these devices as well as their material composition means that in terms of mass and volume, mobile phones represent the most valuable electronic products that are currently found in large numbers in waste streams. End-of-life mobile phones are a high value (from a reuse and resource perspective), high volume (quantity), low cost (residual monetary value) and transient (short lifecycle) electronic product. There are very large numbers of higher education (mainly university) students in the world – there are>2.4 million in the UK alone, 19 million in Europe and 18.2 million in the USA – and they often replace their mobile phones several times before graduation. Thus, because of the potentially significant environmental and economic impacts, a large scale survey of students at 5 UK universities was conducted to assess the behaviour of students with regard to their use and disposal of mobile phones. Additionally, a small scale trial mobile phone takeback service at one of the universities was carried out. The findings indicate that many students replace their phones at least once a year; replacing broken phones, getting upgrades from network operators, remaining “fashionable” and a desire to have a handset with a longer battery life are the main reasons for such rapid replacement. Almost 60% of replaced phones are not sent to reuse or recycling operations but are stockpiled by students mainly as spare/backup phones. Approximately 61% of students own an extra mobile phone with male students replacing their phones more often than females. In particular, the results highlight the potentially huge stockpile of mobile phones – and consequently valuable supplies of rare metals – being held by the public; we estimate that there are 3.7 million phones stockpiled by students in UK higher education alone (29.3 and 28.1 million stockpiled, respectively, for Europe and USA). Although many students are aware of UK mobile phone takeback services, only a moderate number have previously used the services. Students’ recycling of other waste materials such as paper and glass did not have a significant impact on their disposal actions for their unwanted mobile phones, although students who often recycled these waste materials were also the most willing to participate in mobile phone takeback services. Monetary incentives such as cash payments and vouchers have the greatest influence over students’ willingness to utilise takeback services, followed by convenience and ease of use of the services. The paper discusses these findings as well as the outcome of the trial mobile phone takeback. It is suggested that universities should partner with established takeback operators to conduct event-based mobile phone takeback services primarily targeting students. Lessons from mobile phone takeback applicable to takeback services for end-of-life gadgets similar to mobile phones are also discussed. [Copyright &y& Elsevier]

Abstract: Waste lead storage battery is the most important recyclable lead material not only in various European and other OECD countries but also in China. Pollution control of lead has become the focus of people’s attention in the world. A vacuum process for recycling waste lead storage battery was developed in this work. The experimental results showed that all the valuable materials in waste lead storage battery could be satisfactorily recycled by vacuum technologies. The vacuum melting of lead grids and the vacuum reduction of lead pastes produce the lead bullion with the direct recovery ratio of 96.29% and 98.98%, respectively. The vacuum pyrolysis of plastics can produce pyrolysis oil with yield of more than 93 wt.%. These vacuum recycling technologies offer improvements in metallurgical and environmental performance. [Copyright &y& Elsevier]

Abstract: As a result of the continuous change in the design and function of consumer electrical and electronic products, the mechanical and material properties of the obsolete products, called waste electric and electronic equipment (WEEE), are highly variable. The variability within WEEE is explained by the number of different appliances, and the heterogeneity in composition of any given appliance. This paper reports on an extended investigation of the properties of WEEE, in particular small appliances. The investigation focuses on the analysis of the composition of about 700 single appliances. Firstly, analytical methods to characterize the waste equipment are described. The results of the experimental analyses show that the mechanical properties, the material composition, the polymer composition and the chemical composition of WEEE vary not only between equipment types with different functions, but also between single appliances within one equipment type. Data on hazardous and valuable substances in selected equipment types are presented. Using detailed data on the composition of individual appliances to calculate rates of recovery for assumed recycling processes demonstrates that the performance of recycling processes depends strongly on the composition of WEEE. Recycling-oriented characterization is, therefore, a systematic approach to support the design and the operation of recycling processes. [Copyright &y& Elsevier]