Response to waste electrical and electronic equipments in China: legislation, recycling system, and advanced integrated process

Drivers and Pathways for the Recovery of Critical Metals from Waste-Printed Circuit Boards

The ever-increasing importance of critical metals (CMs) in modern society underscores their resource security and circularity. Waste-printed circuit boards (WPCBs) are particularly attractive reservoirs of CMs due to their gamut CM embedding and ubiquitous presence. However, the recovery of most CMs is out of reach from current metal-centric recycling industries, resulting in a flood loss of refined CMs. Here, 41 types of such spent CMs are identified. To deliver a higher level of CM sustainability, this work provides an insightful overview of paradigm-shifting pathways for CM recovery from WPCBs that have been developed in recent years. As a crucial starting entropy-decreasing step, various strategies of metal enrichment are compared, and the deployment of artificial intelligence (AI) and hyperspectral sensing is highlighted. Then, tailored metal recycling schemes are presented for the platinum group, rare earth, and refractory metals, with emphasis on greener metallurgical methods contributing to transforming CMs into marketable products. In addition, due to the vital nexus of CMs between the environment and energy sectors, the upcycling of CMs into electro-/photo-chemical catalysts for green fuel synthesis is proposed to extend the recycling chain. Finally, the challenges and outlook on this all-round upgrading of WPCB recycling are outlined.

Recycling technologies, policies, prospects, and challenges for spent batteries

The recycling of spent batteries is an important concern in resource conservation and environmental protection, while it is facing challenges such as insufficient recycling channels, high costs, and technical difficulties. To address these issues, a review of the recycling of spent batteries, emphasizing the importance and potential value of recycling is conducted. Besides, the recycling policies and strategies implemented in representative countries are summarized, providing legal and policy support for the recycling industry. Moreover, a comprehensive classification and comparison of recycling technologies identify the characteristics and current status of different approaches. The integrated recycling technology provides a better recycling performance with zero-pollution recycling of spent battery. Biorecycling technology is expected to gain a broad development prospect in the future owing to the superiority of energy-saving and environmental protection, high recycling efficiency, via microbial degradation, enzymatic degradation, etc. Consequently, as for the existing recycling challenges of waste batteries, developing new recycling technology and perfecting its recycling system is an indispensable guarantee for the sustainable development of waste battery. Meanwhile, theoretical support is offered for the recycling of spent batteries.

Optimal Decision-Making of Closed-Loop Supply Chains in E-Commerce Platform Considering Sales Cooperations under Environmental Effects and WEEE Regulations

Nowadays, to achieve carbon neutrality, e-commerce platforms participate in the sales and recycling of electrical and electronic products in consideration of waste electrical and electronic equipment (WEEE) regulations and environmental effects. This study builds a Stackelberg game model for an e-commerce closed-loop supply chain (ECLSC) under different sales cooperation modes between a manufacturer of electrical and electronic products and an e-commerce platform. Reverse induction is used to obtain the optimal decision-making and profit of the ECLSC under three sales cooperation modes, considering the influence of environmental effects on optimal decision and objective functions. The results show the following: the sales cooperation mode and environmental cost do not affect the WEEE recovery prices of manufacturers and e-commerce platforms, nor do they affect government subsidy standards for dismantling WEEEs; they are, however, positively correlated with environmental benefits. Furthermore, the wholesale and retail prices of electrical and electronic products under different sales cooperation modes are related to sales cooperation modes and environmental costs. Moreover, the processing fees imposed on the manufacturers are related to the environmental costs of the electrical and electronic products; the thresholds of environmental costs of products for government to levy processing fees are different under different sales cooperation modes. Finally, the environmental cost of products required by the government's levying of processing fees are the lowest under a hybrid model. Generally speaking, under WEEE regulations, governments should levy more processing fees for electrical and electronic products with higher environmental costs. Meanwhile, increased environmental benefits will always increase the profits of supply chain members, but increased environmental costs do not always reduce the profits of supply chain members, and multichannel product sales do not always generate profits for manufacturers.

Debromination with Bromine Recovery from Pyrolysis of Waste Printed Circuit Boards Offers Economic and Environmental Benefits

Bromine is an important resource that is widely used in medical, automotive, and electronic industries. Waste electronic products containing brominated flame retardants can cause serious secondary pollution, which is why catalytic cracking, adsorption, fixation, separation, and purification have gained significant attention. However, the bromine resources have not been effectively reutilized. The application of advanced pyrolysis technology could help solve this problem via converting bromine pollution into bromine resources. Coupled debromination and bromide reutilization during pyrolysis is an important field of research in the future. This prospective paper presents new insights in terms of the reorganization of different elements and adjustment of bromine phase transition. Furthermore, we proposed some research directions for efficient and environmentally friendly debromination and reutilization of bromine: 1) precise synergistic pyrolysis should be further explored for efficient debromination, such as using persistent free radicals in biomass, polymer hydrogen supply, and metal catalysis, 2) rematching of Br elements and nonmetal elements (C/H/O) will be a promising direction for synthesizing functionalized adsorption materials, 3) oriented control of the bromide migration path should be further studied to obtain different forms of bromine resources, and 4) advanced pyrolysis equipment should be well developed.

Analysis of the effect of heating rate on pyrolysis kinetics and product composition of copper-containing waste circuit boards

Pyrolysis is a cost-effective and environmentally benign method for recycling organic waste, which can be converted into high-energy gases and oils. Pyrolysis technology was employed in this study to recycle copper-containing discarded circuit board material and recover copper, glass fibers, and gases and oils with high calorific values. Thermogravimetric analyses (TGA), Fourier transform infrared spectroscopy (FTIR), and gas chromatography-mass spectrometry (GC-MS) were used to evaluate pyrolyses of copper-containing waste circuit board materials conducted at different heating rates (5, 10, 20, and 40 °C/min), and the resulting volatiles were studied in detail. The effects of heating rate on the kinetics and activation energies for pyrolyses of copper-containing waste circuit boards were also investigated by using the Coats-Redfern (C-R) method. The TGA curves and FTIR spectra did not differ significantly for different heating rates, and the main functional groups identified with the FTIR results were O-H, C = C, aromatic benzene, substituted benzene, and C-Br. Additionally, GC-MS analyses showed that the heating rate had a great influence on the pyrolysis products formed; the phenol content decreased with increasing heating rate, and the highest content was realized at 5 ℃/min. Energy dispersive spectroscopy (EDS) analyses showed that bromine was removed from the solid phase products during pyrolysis, while copper was effectively enriched in the feedstock. This indicated that pyrolysis can be used to recover copper-containing waste circuit boards.

Selective extraction of precious metals in the polar aprotic solvent system: Experiment and simulation

The traditional hydrometallurgical process is the mainstream technology to recover precious metals from e-waste, which usually adopts strong acid/base and strong oxide with high environmental cost and energy consumption. In the present study, the selective extraction of precious metals was simulated and experimented with DMF as the solvent and Cl^- ions provided by CaCl₂ and CuCl₂ (oxidizing agent). The leaching and precipitation rates of precious metals (Au, Ag, Pd) can reach more than 98% under optimization conditions. Kinetic data shows that the control model of the leaching process on precious metals was determined by linear fitting of the shrinkage model. The complex trace precious metals were extracted selectively using dimethylglyoxime and deionized water as precipitators by the leaching-precipitation-cycle method. Meanwhile, the waste liquid produced by this reaction process could be cyclically utilized. Furthermore, the leaching mechanism of precious metals was proposed. DMF could be complexed with the metals as well as coordination ions (Cl^-), which can reduce the redox potentials. Cu(II) could be easily reduced to Cu(I) in the DMF system due to the higher second ionization energy of copper, which is not influenced by the hydration effect, thus shifting the equilibrium to the metal leach side. Oppositely, the addition of water promoted the conversion of Cu(I) to Cu(II) since the higher hydration energy of Cu(II) compensates for the second ionization energy. This research opens up a new path of sustainable development and provides basic theory and practical experience for environmentally friendly recovery of precious metals from e-waste.

What drives WEEE recycling? A comparative study concerning legislation, collection and recycling

Waste electrical and electronic equipment (WEEE) has been rising worldwide, and its improper management incurs in economic losses and environmental damage. To provide a better understanding of the forces that drive the management of WEEE, economic and political roles are discussed by comparing the WEEE recycling system of Brazil and Australia. Additional insights about the recycling systems were gathered from interviews with recyclers of both countries (in-loco visits and online/phone surveys). Previous studies show that both countries act as first stage recyclers, dismantling WEEE to ship their valuable components for international recyclers (such as printed circuit boards) while keeping less valuable material (such as polymeric and ferrous pieces). Australia has defined the responsibilities of most agents involved in the WEEE management and recycling setup, while Brazil inadvertently has left the system to be defined through free market regulation. As Brazil recently signed a reverse logistic agreement, there is an important opportunity to channel WEEE into formal routes and implement improvements in the entire recycling system (some suggestions are provided). Australian recyclers were found more organised in their disassembly lines, and some characteristics of the Australian model can be adapted for the Brazilian benefit. In conclusion, economic factors will drive first stage recycling (where labour wages are a small fraction of the total costs) and international downstream recycling, while a political framework is necessary to establish a comprehensive collection system, first stage recycling (where wages are representative) and domestic downstream recycling, given these are generally non-profitable activities in the short term.

Emission of PAHs, PCBs, PBDEs and heavy metals in air, water and soil around a waste plastic recycling factory in an industrial park, Eastern China

Environmental information in recovery of waste plastic in a certificated factory in industrial park in Eastern China is provided in this paper. The process involves raw material storage, washing, closed crushing, closed regeneration, product storage, and waste storage. Particulate matters, heavy metals, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyis (PCBs), and polybrominated diphenyl ethers (PBDEs) emitted from the production process are analyzed. A total of 25 atmospheric samples, 6 soil samples, and 2 water samples are sampled in and around the factory. The following conclusions could be concluded: (1) the concentrations of Cu and Pb are significantly higher than that of Ni, Cr and Cd in total suspended particulate matters; (2) PHE, DghiP, NAP and FLA are the main PAHs components in the air; PHE, FLA, DghiP, NAP, and PYR are the main congeners of PAHs in both washing wastewater and surface water; PHE, NAP, FLA, and CHR are the major congeners in the soil samples; (3) PCB-18, PCB-17 and PCB-31,28 are the main congeners in the air samples; PCB-70 and PCB-110 are the main congeners in soil samples; PCB-49 and PCB-52 are the main congeners in both surface water and washing wastewater; (4) DBDPE and BDE-209 are the main congeners for the all air, water and soil samples. Washing process and crushing process are identified as the main sources of all the above pollutants releases, and management strategies are provided to reduce the pollutants emission and the environmental hazardous caused by the waste plastic recovery process.

Waste Electrical and Electronic Fund Policy: Current Status and Evaluation of Implementation in China

With the accelerated iteration of global electronic and electrical product updates, the demand for electronic and electrical products presents a new trend in which the life cycle of electronic and electrical products is shortened. Waste electrical and electronic equipment (WEEE) products pose a great threat to the global ecological environment, and solving this problem is urgent. Therefore, governments around the world have formulated funding policies for WEEE products, which has led to continuous improvements in such policies. Along these lines, we adopt the circular economy concept, extended producer responsibility theory and life cycle assessment method to comparatively analyse and compare the different fund operation modes in China, Germany, Japan and The Netherlands. In addition, based on the data related to fund policy implementation, we point out the problems in the development of the WEEE industry in China. The analysis results show that although China is the largest WEEE market, it is still in the initial stage and lags behind Western countries in efficiency and cost management. Then, taking as an example ‘Go Green’, an O2O classified recycling platform launched in 2005, this paper performs an extended analysis of the “Internet +” recycling model, which was proposed as a WEEE fund operation solution in China. Finally, we discuss the economic impact of this study on the future implementation and valuation of WEEE fund policy.

Automatic magnetic projection for one-step separation of mixed plastics using ring magnets

Magnetic projection, a novel separation method proposed recently, can separate multiple mixed materials in an efficient and low-cost way. Although promising, existing magnetic projection method cannot achieve the automatic feeding of mixed materials, which limits its applications. To address this challenge, ring magnets were used to replace conventional square magnets in this research. Specifically, a mixture of particles with different densities were fed through the hole of ring magnets and then projected to the corresponding area. Moreover, to increase the magnetic field strength, magnets were superimposed. To predict the projection process, magnetic field analysis was conducted. And from the results, an interesting trap area was found, where the separated materials may be constrained, leading to the failure of projection. The simulation of the projection process revealed that with the increase of the number of magnets (1-3 magnets), the magnetic field strength increased. However, the projection distance will not keep increasing with the increase of the magnetic field strength, which also was verified by experiments (Err within 10%). Based on this principle, an automatic feeding device with ring track and pendulum was designed and manufactured. In the separation experiment, six different plastics, that were PP, ABS, PC, PLA, PET and PVC, were used to verify the separation effect. The experimental results showed that the proposed method can automatically separate a plastic mixture with a recovery rate of over 95%. This study presents a break-through in magnetic projection, laying the foundation for the practical application of magnetic projection.

Environmentally friendly automated line for recovering aluminium and lithium iron phosphate components of spent lithium-iron phosphate batteries

Lithium iron phosphate (LFP) batteries contain metals, toxic electrolytes, organic chemicals and plastics that can lead to serious safety and environmental problems when they are improperly disposed of. The published literature on recovering spent LFP batteries mainly focuses on policy-making and conceptual design. The production line of recovering spent LFP batteries and its detailed operation are rarely reported. A set of automatic line without negative impact to the environment for recycling spent LFP batteries at industrial scale was investigated in this study. It includes crushing, pneumatic separation, sieving, and poison gas treatment processes. The optimum retaining time of materials in the crusher is 3 minutes. The release rate is the highest when the load of the impact crusher is 800 g. An air current separator (ACS) was designed to separate LFP from aluminium (Al) foil and LFP powder mixture. Movement behaviour of LFP powder and Al foil in the ACS were analysed, and the optimized operation parameter (35.46 m/s) of air current speed was obtained through theoretical analysis and experiments. The weight contents of an Al foil powder collector from vibrating screen-3 and LFP powder collector from bag-type dust collector are approximately 38.7% and 52.4%, respectively. The economic cost of full manual dismantling is higher than the recovery production line. This recycling system provides a feasible method for recycling spent LFP batteries.

Electronic waste generation, recycling and resource recovery: Technological perspectives and trends

The growing population and increased disposal of end-of-life (EoL) electrical and electronic products have caused serious concerns to the environment and human health. Electronic waste (e-waste) is a growing problem because the quantity and the rate at which it is generated has increased exponentially in the last 5 years. The rapid changes or upgradation in technologies, IT requirements for working or learning from home during COVID-19, manufacturers releasing new electronic gadgets and devices that serves the consumers comfort and a declension in services has contributed to an increase in the e-waste or waste of electrical and electronic equipment (WEEE) generation rates. The current status of e-waste generation, handling procedures and regulatory directives in USA, EU, China, India, Vietnam and Gulf Cooperation Council (GCC) countries are presented in this review. The recent developments in e-waste recycling methods/recovery of base and precious metals, the advantages and limitations of hydrometallurgy, pyrometallurgy, biohydrometallurgy and pyrolysis are discussed. Considering the impediments in the present technologies, the extraction of valuable resources, i.e. precious metals, from e-waste using suitable biocatalysts shows promising applications. This review also stresses on the research needs to assess the economic effects of involving different unit operations/process industries for resource recovery, reuse and recycling.

Management status of waste lithium-ion batteries in China and a complete closed-circuit recycling process

Lithium-ion batteries (LIBs) were used extensively in people's lives, especially with the vigorous promotion of new energy vehicles, which led to the generation of a large number of waste LIBs. In consideration of the enormous quantity, environmental risk, and resource properties, many countries have issued a series of laws and regulations to manage waste LIBs and developed a lot of recycling technologies. As the biggest producer of batteries in the world, China has also taken necessary measures to deal with this situation. This paper presents the latest regulations of waste LIBs in China and reviews the recycling strategies of waste LIBs, especially physical recycling methods. Based on the analysis of the current management status of waste LIBs in China and the recycling technologies, some management suggestions, and a complete closed-circuit recycling process including cascade utilization and resource recovery were put forward. A rough economic evaluation of the process was also conducted to demonstrate the economic feasibility of the proposed process. The purpose of this paper is to provide some valuable references for decision-making bodies in the improvement of waste lithium-ion battery management and to provide an environmentally friendly and industrial feasible recycling process for reference.

Assessment of polybrominated diphenyl ethers and emerging brominated flame retardants in Pheretima (a Traditional Chinese Medicine): Occurrence, residue profiles, and potential health risks

China produces and consumes large quantities of brominated flame retardants (BFRs) as well as several other unregulated electronic waste recycling activities, causing high BFR concentrations in the natural environment. Thus, Traditional Chinese Medicines (TCMs) may be contaminated by legacy BFRs (e.g. polybrominated diphenyl ethers (PBDEs)) and emerging BFRs (eBFRs, such as decabromodiphenyl ethane (DBDPE)) during growth, processing, packaging, and transportation. Pheretima, which is a typical animal drug recorded in Chinese Pharmacopoeia, was used as an example to evaluate human exposure to BFRs through TCM intake. This study is the first to determine 25 PBDEs and 5 eBFRs in Pheretima and estimate the daily BFR intake via Pheretima-containing TCMs. Twenty-seven Shanghai Pheretima and fifty-one Guang Pheretima samples were collected between March and June 2019 in southeast China. High BFR detection frequencies were found in Pheretima, of which BDE-209 and DBDPE were the most predominant analytes. The total PBDE contents ranged from 73 pg/g to 8,725 pg/g, while that of the eBFRs varied between 115 pg/g and 2,824 pg/g. The profiles and abundances were found to be species- and origin-dependent. However, the traditional processing of Pheretima may reduce BFR residues. Based on the usual clinical doses of Pheretima and the available chronic oral reference doses of BDE-47, 99, 153, and 209, the mean (95th percentile) of the total hazard quotient was estimated to be 9.1 × 10^-5 (2.7 × 10^-4). Therefore, there is little risk related to BFR exposure for patients taking formulated Pheretima-containing TCMs. However, it is necessary to establish routine monitoring programs for the co-existence of pollutants in TCMs to perform a systematic and comprehensive risk assessment.

Polybrominated diphenyl ethers (PBDEs) in the Danjiangkou Reservoir, China: identification of priority PBDE congeners

Although the production of polybrominated diphenyl ethers (PBDEs) has been phased out over the past decade worldwide, they are still potentially hazardous to the environment due to their persistence and toxicity. This study investigated the levels of 55 PBDEs in water and sediments from the Danjiangkou Reservoir, China. The levels of PBDEs were in the range of not detected (ND)-286.67 ng/L in water and ND-236.04 ng/g in sediments. BDE209 was the predominant PBDE congener and constituted 15-50% and 44-68% of the total PBDEs in water and sediments, respectively. Commercial pentaBDE products (70-5DE, DE-71) were the dominant source of tetraBDE, pentaBDE, and hexaBDE, while commercial octaBDE (79-8DE) and decaBDE (102E and 82-0DE) products were the main sources of nonaBDE and decaBDE in water. PBDEs in sediments mainly stemmed from commercial decaBDE products and combustion sources. BDE-209 posed high ecological risks to aquatic organisms and dominated the total ecological risks of PBDEs. No cancer risks and non-cancer risks were observed for PBDEs. A ranking method based on four criteria, i.e., detection frequency, concentration, ecological risk, and health risks, was proposed, and 17 PBDEs were identified as high priority PBDEs for future monitoring and management in the Danjiangkou Reservoir.

Effect of Chloride Ions on Electro-Coagulation to Treat Industrial Wastewater Containing Cu and Ni

A series of experiments with different NaCl concentrations added to the PCB (printed circuit board) wastewater were prepared to investigate the chloride effect on the formation of aluminum floc and removal efficiency of Cu and Ni. The effects of pH, current density, and different concentration of NaCl were studied and the results are discussed. Results imply that chloride ions are favored to avoid the passivation of the aluminum anode in the EC (electro-coagulation) system. Chloride ions used as the electrolyte can facilitate the release of Al3+, which results in the current efficiency of over 100% in the EC system. For the PCB factory’s wastewater, the EC system could remove Cu2+ and Ni2+ effectively (both Cu and Ni concentration of treated wastewater was less than 1.0 mg/L within three minutes). PCB wastewater’s pH value could maintain stably about 9.0 in the EC system when the initial pH value was around 2.5. The estimated electricity consumption for treating PCB wastewater by the EC process was about 0.894 kWh for each meter of cubic wastewater.

Evaluation of a new extended producer responsibility mode for WEEE based on a supply chain scheme

China is promoting extended producer responsibility (EPR) for waste electrical and electronic equipment (WEEE). However, the present EPR policy in China, in fund mode, has been facing the challenge of fund deficit severely since 2016. A new sustainable EPR mode is needed to solve this problem. In this paper, a mandatory recycling EPR mode is designed and studied as a potential solution. A quantitative evaluation system is innovatively established to evaluate the effectiveness of the mode and to compare the new mode to the present mode. The evaluation system first summarizes a supply chain scheme of electrical and electronic equipment (EEE) in each mode, which describes the life cycle of China's EEE from products to wastes to renewed resources. The supply chain schemes are complex since they contain five to six different stakeholders. Then classical game theory models are applied to the supply chain scheme based on the interaction among different stakeholders to calculate the indicators used for evaluation. At last, the two modes are compared in terms of economic, environmental and social effects in the case of the air-conditioner market. Results show the mandatory recycling mode is similar to the fund mode in economic and social effects. It is more financially sustainable, capable of enabling a higher recycling rate and more beneficial to certified recycling companies. Therefore, applying the recycling obligation mode in the future to maintain the EPR system is recommended.

Inconsistencies of e-waste management in developing nations - Facts and plausible solutions

Electronic and electrical equipment (EEE) became an integral part of daily life and had an immense influence on the economy. The skyrocketing demand, progressive technologies, and high dependency resulted in inconceivable utilization of EEE. However, these scientific expansions shortened the life span of EEE, thereby generating massive volumes of waste electronic and electrical equipment (WEEE). On a global perspective, Oceania generates a per capita of 17.3 kg/inh (inhabitants), followed by Europe 16.6 kg/inh, America 11.6 kg/inh, Asia 4.2 kg/inh and the least contribution by Africa 1.9 kg/inh. As known, EEE comprises complex metallic and non-metallic fractions causing severe discrepancies within the ecosystem, endangering the living species; if not dealt with properly. Thus, there is a pressing need of immediate addressal on the effective e-waste management strategies both from developed and developing countries. On the spin side, the separation of the precious fractions from the EEE on the end-of-life may be a twin dimensional strategy of economic addition, and plummeting the alarming level threats to ecology. However, these menaces are well tackled by the developed countries to some extent by the stringent law enactments, establishing proper recycling facilities, and trading to the underdeveloped and developing nations. But, the majority of the developing and under developed nations lacks the statutes, gaps in policy making, socio-economic-cultural barriers, technology, and the appropriate treatment facilities. In addition, the review identified ten major shortfalls (10L's) refraining the effective e-waste management, especially in the developing and under developed nations. Among which, integration of the formal and informal sectors, mandated network registry, stringent law enforcements, regulated transboundary movements, manufacturers responsibility, consumer awareness and improved eco designs, investing on effective recycling facilities, and improved disposal facilities holds the key. Further, replacing the traditional and conventional procedures with the futuristic and eco-friendly approaches such as chelation, inducing ionic liquids, integrated processes or hybrid technologies, micro factories, photo catalysis, and green adsorption will substantially harness the current barriers of the e-waste management. Finally, the present review will be a thorough glancing for the future research of e-waste management of meso-micro-macro scales.

Effect of ionic liquid [MIm]HSO4 on WPCB metal-enriched scraps refined by slurry electrolysis

Waste printed circuit boards (WPCBs) are usually dismantled, crushed, and sorted to WPCB metal-enriched scraps, still containing an amount of non-metallic materials. This research used slurry electrolysis to refine these WPCB metal-enriched scraps and to examine if a standard ionic liquid, [MIm]HSO₄, can replace H₂SO₄ in the system. The impact of the refinement process on metal migration and transformation is discussed in detail. The results demonstrated that metals in WPCB metal-enriched scraps could be successfully refined using slurry electrolysis, and [MIm]HSO₄ can be used to replace H₂SO₄ in the system. When 80% of H₂SO₄ was replaced by [MIm]HSO₄ (electrolyte of 200 mL, 30 g/L CuSO₄·5H₂O, 60 g/L NaCl, 130 g/L H₂SO₄, and 1.624 A for 4 h), the total metal recovery rate is 85%, and the purity, current efficiency, and particle size of cathode metal powder were 89%, 52%, and 3.77 μm, respectively. Moreover, the microstructure of the cathode metal powder was dendritic in the H₂SO₄-CuSO₄-NaCl slurry electrolysis system, whereas at an 80% [MIm]HSO₄ substitution rate slurry electrolysis system, the cathode metal powder was irregular and accumulated as small-sized spherical particles. Thus, replacing inorganic leaching solvents with ionic liquids may provide a potential choice for the resources in WPCB metal-enriched scraps.

Improved bioleaching efficiency of metals from waste printed circuit boards by mechanical activation

The low bioleaching efficiency of Acidithiobacillus ferrooxidans results in its sparse industrial application for metal extraction from waste printed circuit boards (WPCBs). To improve the bioleaching efficiency of Acidithiobacillus ferrooxidans, we propose the use of mechanical activation to dispose WPCBs prior to performing bioleaching. Response surface methodology (RSM), scanning electron microscope- energy dispersive spectrometer (SEM-EDS), and laser particle size analyzer (LPSA) were used to optimize and analyze the mechanical activation process, respectively. The optimal conditions for mechanical activation was a milling time of 2 h, milling speed of 340 r min^-1, and ball material ratio (w/w) of 10/1; the bioleaching rates of Cu, Ni, and Zn were 94.33%, 90.69%, and 90.78%, respectively. The bioleaching rates of Cu, Ni, and Zn were 74.75%, 70.46%, and 71.05%, respectively, without mechanical activation pretreatment. SEM-EDS and LPSA analyses indicated that mechanical activation could lead to a smaller particle size and expose wrapped metals, thus improving the bioleaching efficiency oyf tyhe metals inside the WPCBs. The electrode potential of the metals was likely changed by the mechanical activation, resulting in an improvement of their bioleaching efficiency. Additionally, the bioleaching rates of Pb, Cr, and Cd after mechanical activation pretreatment were 10.29%, 74.89%, and 54.12%, respectively. Contrastingly, the bioleaching rates of Pb, Cr, and Cd without mechanical activation pretreatment were 5.18%, 59.97%, and 37.12%, respectively. Thereinto, the precipitation of PbSO₄ may result in a decrease of leached Pb. We propose a mechanical activation process for improving the bioleaching efficiency of metals from WPCBs.

Long-term Persistent Organic Pollutants Exposure Induced Telomere Dysfunction and Senescence-Associated Secretary Phenotype

Environmentally persistent organic pollutant (POP) is the general term for refractory organic compounds that show long-range atmospheric transport, environmental persistence, and bioaccumulation. It has been reported that the accumulation of POPs could lead to cellular DNA damage and adverse effects of on metabolic health. To better understand the mechanism of the health risks associated with POPs, we conducted an evidence-based cohort investigation (n = 5,955) at the Jinghai e-waste disposal center in China from 2009 to 2016, where people endure serious POP exposure. And high levels of aging-related diseases, including hypertension, diabetes, autoimmune diseases, and reproductive disorders were identified associated with the POP exposure. In the subsequent molecular level study, an increased telomere dysfunction including telomere multiple telomere signals, telomere signal-free ends, telomere shortening and activation of alternative lengthening of telomeres were observed, which might result from the hypomethylated DNA modification induced telomeric repeat-containing RNA overexpression. Moreover, dysfunctional telomere-leaded senescence-associated secretory phenotype was confirmed, as the proinflammatory cytokines and immunosenescence hallmarks including interleukin-6, P16^INK4a, and P14^ARF were stimulated. Thus, we proposed that the dysfunctional telomere and elevated systemic chronic inflammation contribute to the aging-associated diseases, which were highly developed among the POP exposure individuals.

Towards minimization of secondary wastes: Element recycling to achieve future complete resource recycling of electronic wastes

Recycling resources from millions of tons of e-wastes are a global challenge. E-wastes is complex and contains both toxic organics and valuable metals. Therefore, the technologies for e-wastes recycling are totally different from those used for mineral separation. Current technologies for e-wastes tend to focus on recycling materials with high economic value and ignore components that cannot be recycled or have low reuse value. As a result, some secondary pollution problems inevitably occur due to the recycling process. Based on these problems, we summarize the universal characteristics of e-wastes and explore new approaches to achieve complete resource recycling of e-wastes with minimum secondary waste generation. A concept of element recycling is proposed to achieve complete resource recycling of e-wastes in the study. We can use the properties of the elements in different types of e-wastes to achieve e-wastes recycling, i.e., recycle of elements in e-wastes. Under the guidance of element recycling, various e-wastes types have common connections. If element recycling in e-wastes is realized, all components in e-wastes can be fully recycled without/with minimal production of secondary waste. The two case studies are discussed to clarify the concept and principle of element recycling. This study explores the recycling of e-wastes from a new perspective-element recycling in e-wastes. The concept of element recycling is significant for resource recycling from e-wastes.

Reflection of concentrations of polybrominated diphenyl ethers in health risk assessment: A case study in sediments from the metropolitan river, North China

As a developed city in North China, Tsingtao is believed to be suffering from the pollution of polybrominated diphenyl ethers (PBDEs) due to the rapid industrialization and urbanization in recent years. In this work, 8 PBDE congeners were detected in sediments from Moshui River, Tsingtao. BDE-209 and sum of 7 low brominated PBDE congeners (∑₇PBDEs, excluding BDE-209) ranged from 10.2 × 10^-3 to 237 × 10^-3 mg kg^-1 and from 1.62 × 10^-3 to 23.1 × 10^-3 mg kg^-1 d.w., respectively. PBDE concentrations decreased in the order of midstream > downstream > upstream, attributing to the discrepancies in anthropogenic activities among these areas. Principal component analysis coupled with multiple linear regression (PCA-MLR) revealed that 24.4% of PBDEs were derived from surface runoff of contaminated soils, 58.2% from direct discharge of local sources and 17.4% from atmospheric deposition. The probabilistic health risk assessment of PBDEs was performed by using Monte Carlo simulation. The carcinogenic and non-carcinogenic risks based on total PBDEs were low for children and teens, whilst severe for adults. However, based on bioaccessible PBDEs (in vitro gastrointestinal model), there was no obvious health risk for the three age groups. To the best of our knowledge, the present study was the first attempt to assess the health risk by using bioaccessible PBDEs in sediments.

Exploring "Internet+Recycling": Mass balance and life cycle assessment of a waste management system associated with a mobile application

Individual users cannot readily access the collection channels is a persistent problem in municipal solid waste (MSW) management, resulting in low MSW collection rates. A new waste management model, "Internet+Recycling", has come into being; this model enables individuals to arrange collection appointment through various online platforms, then the collectors pick up the waste on-site. It is believed that "Internet+Recycling" can be a solution to mitigate the collection barrier in MSW management, as it provides individuals a convenient access to formal waste management systems. However, whether this emerging MSW collection model would bring environmental benefits is yet unknown. We here quantitatively examine the mass balance and environmental performance of MSW recycling associated with the use of such a "Internet+Recycling" mobile application - Aibolv. All transactions occurred on the mobile application within a period of six monthare included, and all related activities are modeled using the methodology that combines material flow analysis (MFA) and life cycle assessment (LCA). According to the extant MSW management legislation in China, we classify the collected MSW into three categories, subsidized waste electric and electronic equipment (WEEE) like television and refrigerator - T1, unsubsidized WEEE like mobile phone - T2, and other recyclables like paper and fabric - T3. The MFA results show that plastics and common metals are the dominate secondary material streams, and glass, precious metals and battery metals are mainly recovered from WEEE. The LCA results indicate that the disposal of the T2 waste has the highest environmental savings, due to the recovery of precious metals. Increased remanufacturing rates impart negative impacts, while increments in the quantity of spent mobile phones could significantly improve overall environmental performance. Based on the acquired results, recommendations are provided for facilitating the future development of "Internet+Recycling", and limitations of this work are identified as well.

Mass balance-based inventory of heavy metals inputs to and outputs from agricultural soils in Zhejiang Province, China

It is important to understand the status and extent of soil contamination with heavy metals to make sustainable management strategies for agricultural soils. Input and output inventory of heavy metals in agricultural soil of Zhejiang Province was systematically studied. The results showed that atmospheric deposition was responsible for 47.88% and 76.87% of the total Cr and Pb inputs, respectively. Livestock manures accounted for approximately 54-85% of the total As, Cu, and Zn inputs. Livestock manure and irrigation were the main sources of Hg, contributed 50.25% and 38.63% of the total inputs, respectively. Ni was derived mainly from atmospheric deposition (57.86%), followed by irrigation (22.69%). As for Cd, the relative contributions of atmospheric deposition, irrigation, and livestock manure were similar. Crop harvesting and leaching were found to be the dominant output pathways of the soil elements Cd, Cu, Hg, and Zn, being responsible for 74.43-83.62% of the total outputs. Surface runoff was the dominant output pathway for As, Cr, Ni, and Pb, accounting for approximately 73.36%, 46.32%, 54.16%, and 48.11% of the total outputs, respectively. According to prediction and early warning, Cd is the priority control pollutant in agricultural soil. This work will assist in developing strategies for reducing heavy metal inputs to agricultural soil and effectively targeting policies to protect soil environment from long-term heavy metal accumulation.

Measuring the sustainability of tin in China

Tin is a component of many items used in daily activities, including solder in consumer electronics, tin can containing food and beverages, polyvinyl chloride stabilizers in construction products, catalysts in industrial processes, etc. China is the largest producer and consumer of refined tin, and more than 60% of this refined tin is applied in the electronics sector as solder. China is the leader in global economic growth; simultaneously, China is also a major producer and consumer of electrical and electronic equipment (EEE). Thus, future tin supply and demand in China are forecasted, based on the gross domestic product per capita and the average consumption of refined tin in past five years. Current tin reserves and identified resources in China can meet the future two decades of mine production, but import of tin will also be critical for China's future tin consumption. However, there will be a lot of uncertainty for import of tin from other countries. At the same time, virgin mining of geological ores is a process of high energy consumption and destruction of the natural environment. Hence recycling tin from Sn-bearing secondary resources like tailings and waste electrical and electronic equipment (WEEE) can not only address the shortage of tin mineral resources, but also save energy and protect the ecological environment.

Application of High-Resolution NMR and GC-MS to Study Hydrocarbon Oils Derived from Noncatalytic Thermal Transformation of e-Waste Plastics

The increases in the volumes of electronic waste have become an aggravating environmental, economic, and social health issue in recent times. This study investigates the conversion of e-waste plastics into hydrocarbon oils via noncatalytic thermal transformation followed by an in-depth characterization of these oils using diverse analytical techniques such as gas chromatography-mass spectrometry (GC-MS), Fourier transform infrared (FTIR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy. In particular, NMR spectroscopy is a key analytical tool utilized in this study to gain a comprehensive insight into the chemical nature of the resultant oils along with a semiquantitative investigation of the changes in their composition over a temperature range of 800-1200 °C. The one-dimensional (1D) ¹H and two-dimensional (2D) heteronuclear single-quantum correlation spectra were acquired for the oils, wherein the 2D NMR spectrum provided improved resolution of peaks to address the overlaps encountered in the 1D spectrum. The experimental results obtained from GC-MS, FTIR spectroscopy, and NMR spectroscopy were found to align well with each other. The oils produced in this study have a high calorific value of 38.27 MJ/kg and thus may find use in several applications. A detailed mechanism for the thermal degradation of styrene acrylonitrile plastics and the formation of major products is elucidated in this study.

Recycling of zincite (ZnO) via uptake of hydrogen halides

We investigate chemical interplay between HCl/HBr and zincite surfaces as a representative model for structures of zinc oxides in EAFD.

Influence of human activities and organic matters on occurrence of polybrominated diphenyl ethers in marine sediment core: A case study in the Southern Yellow Sea, China

The Southern Yellow Sea (SYS) is an important reservoir of anthropogenic organic contaminants, such as polybrominated diphenyl ethers (PBDEs). To reconstruct the historical records of PBDEs and examine their relationships with the human activities and organic matters, a²¹⁰Pb-dated sediment core was collected from the central mud area in the SYS. The concentrations of tri-to hepta-BDEs (∑₇PBDEs) and BDE-209 ranged from 9.8 to 99.8 pg g^-1 d.w. and from 12.1 to 855.4 pg g^-1 d.w., respectively, both displaying the increasing trends from the bottom to the surface. More importantly, there was a faster increase for PBDEs since the 1990s, especially for BDE-209, which responded well with the rapid economic growth, and the increases of urbanization and industrialization in the local areas of the SYS. The analogously vertical patterns and significant relationships between PBDEs and total organic carbon (TOC) implied the TOC-dependent deposition of PBDEs in the core. Furthermore, multiple biomarker-based proxies of terrestrial organic matter (TOM) and marine organic matter (MOM) were introduced to systematically investigate the different effects of TOM and MOM on PBDE deposition in the SYS. The similarly down-core profiles and significant correlations were found between PBDEs and the MOM proxies (sum of rassicasterol, dinosterol and C₃₇ alkenones (∑A + B + D) and marine TOC) as well as the branched and isoprenoid tetraether (BIT), but not for TOM proxies (∑C₂₇+C₂₉+C₃₁n-alkanes, terrestrial and marine biomarker ratio (TMBR) and terrestrial TOC), indicating that MOM was an important factor driving PBDE deposition in the sediment core from the SYS.

Internet of things and Big Data as potential solutions to the problems in waste electrical and electronic equipment management: An exploratory study

Management of Waste Electrical and Electronic Equipment (WEEE) is a vital part in solid waste management, there are still some difficult issues require attentionss. This paper investigates the potential of applying Internet of Things (IoT) and Big Data as the solutions to the WEEE management problems. The massive data generated during the production, consumption and disposal of Electrical and Electronic Equipment (EEE) fits the characteristics of Big Data. Through using the state-of-the-art communication technologies, the IoT derives the WEEE "Big Data" from the life cycle of EEE, and the Big Data technologies process the WEEE "Big Data" for supporting decision making in WEEE management. The framework of implementing the IoT and the Big Data technologies is proposed, with its multiple layers are illustrated. Case studies with the potential application scenarios of the framework are presented and discussed. As an unprecedented exploration, the combined application of the IoT and the Big Data technologies in WEEE management brings a series of opportunities as well as new challenges. This study provides insights and visions for stakeholders in solving the WEEE management problems under the context of IoT and Big Data.

Environmental friendly technology for aluminum electrolytic capacitors recycling from waste printed circuit boards

up to now, the recycling of e-waste should be developed towards more depth and refinement to promote industrial production of e-waste resource recovery. in the present study, the recycling of aluminum electrolytic capacitors (AECs) from waste printed circuit boards (WPCBs) is focused on. First of all, AECs are disassembled from WPCBs by a self-designed machine; meanwhile, the disassembled AECs are subjected to an integrated process, involving heating treatment, crushing, sieving, and magnetic separating, to recover aluminum and iron; finally, the off-gas and residue generated during the aforementioned processes are analyzed to evaluate environmental risks. The results indicate that 96.52% and 98.68% of aluminum and iron, respectively, can be recovered from AECs under the optimal condition. The off-gas generated during the process is mainly composed of elements of C, H, and O, indicating that the off-gas is non-toxic and could be re-utilized as clean energy source. The residue according with toxicity characteristics leaching standard can be landfilled safely in sanitary landfill site. The present study provides an environmentally friendly and industrial application potential strategy to recycle AECs to promote e-waste recycling industry.

Key factors of eddy current separation for recovering aluminum from crushed e-waste

Recovery of e-waste in China had caused serious pollutions. Eddy current separation is an environment-friendly technology of separating nonferrous metallic particles from crushed e-waste. However, due to complex particle characters, separation efficiency of traditional eddy current separator was low. In production, controllable operation factors of eddy current separation are feeding speed, (ωR-v), and S_p. There is little special information about influencing mechanism and critical parameters of these factors in eddy current separation. This paper provided the special information of these key factors in eddy current separation of recovering aluminum particles from crushed waste refrigerator cabinets. Detachment angles increased as the increase of (ωR-v). Separation efficiency increased with the growing of detachment angles. Aluminum particles were completely separated from plastic particles in critical parameters of feeding speed 0.5m/s and detachment angles greater than 6.61deg. S_p/S_m of aluminum particles in crushed waste refrigerators ranged from 0.08 to 0.51. Separation efficiency increased as the increase of S_p/S_m. This enlightened us to develop new separator to separate smaller nonferrous metallic particles in e-waste recovery. High feeding speed destroyed separation efficiency. However, greater S_p of aluminum particles brought positive impact on separation efficiency. Greater S_p could increase critical feeding speed to offer greater throughput of eddy current separation. This paper will guide eddy current separation in production of recovering nonferrous metals from crushed e-waste.

Innovating e-waste management: From macroscopic to microscopic scales

Waste electrical and electronic equipment (WEEE or e-waste) has become a global problem, due to its potential environmental pollution and human health risk, and its containing valuable resources (e.g., metals, plastics). Recycling for e-waste will be a necessity, not only to address the shortage of mineral resources for electronics industry, but also to decline environmental pollution and human health risk. To systematically solve the e-waste problem, more attention of e-waste management should transfer from macroscopic to microscopic scales. E-waste processing technology should be significantly improved to diminish and even avoid toxic substance entering into downstream of material. The regulation or policy related to new production of hazardous substances in recycled materials should also be carried out on the agenda. All the findings can hopefully improve WEEE legislation for regulated countries and non-regulated countries.

Polybrominated Diphenyl Ethers (PBDEs) in Surface Soils across Five Asian Countries: Levels, Spatial Distribution, and Source Contribution

A total of 23 polybrominated diphenyl ether (PBDE) congeners were measured in soil samples collected in areas with no known point source [urban/rural/background (U/R/B) sites] and in areas with known point source [brominated flame retardant (BFR)-related industrial sites (F sites) and e-waste recycling sites (E sites)] across five Asian countries. The highest PBDE concentrations were found in BFR-related industrial and e-waste recycling sites. The concentrations of PBDEs in U/R/B sites decreased in the following order: urban > rural > background sites. Total PBDE concentrations were dominated by BDE-209, while BDE-17, -85, -138, -191, -204, and -205 were the least abundant compounds. In both urban sites and rural sites, the mean concentrations of total PBDEs (∑₂₃BDEs) in soils decreased in the following order: Japan > China > South Korea > India > Vietnam. The concentrations of PBDEs in soils were comparable with those reported in other studies. Among the three commercial PBDE mixtures, relatively large contributions of commercial penta-BDE were observed in Vietnam, whereas deca-BDE was the dominant form in mixtures contributing from 55.8 ± 2.5 to 100.0 ± 1.2% of the total PBDEs in soils collected from other four countries. Regression analysis suggested that local population density (PD) is a good indicator of PBDEs in soils of each country. Significant and positive correlation between soil organic content and PBDE level was observed in Chinese soil for most nondeca-BDE homologues with their usage stopped 10 years ago, indicating its important role in controlling the revolatilization of PBDEs from soil and changing the spatial trend of PBDE in soil from the primary distribution pattern to the secondary distribution pattern, especially when primary emission is ceased.

WEEE management in Europe and China - A comparison

Over the last years Europe and China have developed specific regulations to address the challenge of managing Waste Electrical and Electronic Equipment (WEEE). Households in today's urban China are similarly equipped with electrical and electronic appliances as households in European metropolitan areas, which in turn will lead to similar per capita generation rates in WEEE. While the challenge is a similar one, the systems, technologies and legislation in place in Europe and China are partly different, partly aligned to each other. In Europe WEEE collection is based on existing municipal structures. Additionally, retail and other take-back channels are in place. In China the informal sector dominates WEEE collection, being more competitive and flexible and offering pecuniary reimbursement to consumers. In Europe manual dismantling as a first treatment step has been gradually replaced by mechanical break up of appliances, followed by sorting out of hazardous and valuable components. In the subsequent second treatment level, cathode ray tubes are separated, whereby compound materials like motors and coils are mechanically treated, printed circuit boards go to special smelters, and plastics are separated and partly recycled. In China large formal dismantling capacities have been set up in recent years. There dismantling practices follow similar principles as in European plants; however, further processing is only partly implemented in Chinese recycling facilities. Specifically metallurgical treatment of printed circuit boards is still not existent in China. Companies selling electrical and electronic products within the EU are obliged to organise collection and treatment. This has led to a larger number of producer responsibility organisations. Financed and controlled by producers and importers, these systems aim to fulfil legal requirements at optimised costs subject to compliance with environmental standards and monitoring requirements. The Chinese system is built on a state controlled fund which subsidies formal recyclers. For these recyclers this financial support is essential to compete with informal recyclers, who operate at lower costs and do not necessarily comply with environmental standards.

Morphology, mechanical and thermal oxidative aging properties of HDPE composites reinforced by nonmetals recycled from waste printed circuit boards

In this study nonmetals recycled from waste printed circuit boards (NPCB) is used as reinforce fillers in high-density polyethylene (HDPE) composites. The morphology, mechanical and thermal oxidative aging properties of NPCB reinforced HDPE composites are assessed and it compared with two other commercial functional filler for the first time. Mechanical test results showed that NPCB could be used as reinforcing fillers in the HDPE composites and mechanical properties especially for stiffness is better than other two commercial fillers. The improved mechanical property was confirmed by the higher aspect ratio and strong interfacial adhesion in scanning electron microscopy (SEM) studies. The heat deflection temperature (HDT) test showed the presence of fiberglass in NPCB can improve the heat resistance of composite for their potential applications. Meanwhile, the oxidation induction time (OIT) and the Fourier transform infrared (FTIR) spectroscopy results showed that NPCB has a near resistance to oxidation as two other commercial fillers used in this paper. The above results show the reuse of NPCB in the HDPE composites represents a promising way for resolving both the environmental pollution and the high-value reuse of resources.

Integrated bioleaching of copper metal from waste printed circuit board-a comprehensive review of approaches and challenges

Waste electrical and electronic equipment (e-waste) is the most rapidly growing waste stream in the world, and the majority of the residues are openly disposed of in developing countries. Waste printed circuit boards (WPCBs) make up the major portion of e-waste, and their informal recycling can cause environmental pollution and health risks. Furthermore, the conventional disposal and recycling techniques-mechanical treatments used to recover valuable metals, including copper-are not sustainable in the long term. Chemical leaching is rapid and efficient but causes secondary pollution. Bioleaching is a promising approach, eco-friendly and economically feasible, but it is slower process. This review considers the recycling potential of microbes and suggests an integrated bioleaching approach for Cu extraction and recovery from WPCBs. The proposed recycling system should be more effective, efficient and both technically and economically feasible.

An environmentally friendly technology of disassembling electronic components from waste printed circuit boards

Electronic components (ECs) disassembling from waste printed circuit boards (WPCBs) is the first and essential step in WPCBs recycling chain. Over the past decades, primitive methods like simply heating WPCBs on a coal-heated plate to melt solders are dominated in practice, causing serious environmental pollution and also putting a real threat to the human health. In order to solve this problem, in this article, an automatic system in pilot-scale for ECs disassembling from WPCBs is designed, manufactured, and investigated. This system contains two parts: ECs automatic disassembly and off-gas purification. Meanwhile, WPCBs from television (i.e., TV-WPCBs) and personal computer (i.e., PC-WPCBs) are used for disassembling tests, respectively. When the disassembling temperature, rotating speed, and incubation time are 265±5°C, 10rpm, and 8min, respectively, the solder can be completely removed from both TV-WPCBs and PC-WPCBs. No pollutant is discharged from this system. Finally, the disassembling procedures for ECs from both TV-WPCBs and PC-WPCBs are suggested to promote WPCBs disassembling in an environment-friendly way, without threaten the environment and human health.

Impacts of BDE209 addition on Pb uptake, subcellular partitioning and gene toxicity in earthworm (Eisenia fetida)

Lead (Pb) and decabromodiphenyl ether (BDE209) are the mainly co-existed contaminants at e-waste recycling sites. The potential toxicity of Pb (250 μg g(-1)) to earthworm Eisenia fetida in the presence of BDE209 (1, 10 and 100 μg g(-1)) was determined during 14-d incubation period. Compared to Pb treatment alone, the co-exposure with 1 μg g(-1) BDE209 barely affected Pb uptake, subcellular partitioning and gene expression; however, histopathological changes in earthworms' body wall (epidermal, circular and longitudinal muscles) demonstrated that 10 and 100 μg g(-1) BDE209 additions enhanced Pb uptake and altered its subcellular partitioning, indicating that Pb redistributed from fractions E (cell debris) and D (metal-rich granules) to fraction C (cytosols); Additionally, BDE209 supply significantly inhibited (p<0.05) the induction of SOD (superoxide dismutase) and CAT (catalase) gene expressions (maximum down-regulation 59% for SOD gene at Pb+100 μg g(-1) BDE209 and 89% for CAT gene at Pb+10 μg g(-1) BDE209), while facilitated (p<0.05) Hsp90 (heat shock protein 90) gene expression with maximum induction rate of 120% after exposure to Pb+10 μg g(-1) BDE209. These findings illustrate the importance of considering environmental BDE209 co-exposure when assessing Pb bioaccumulation and toxicity in multi-contaminated soil ecosystems.

Levels and ecological risk assessment of metals in soils from a typical e-waste recycling region in southeast China

Due to the high threat to human health and the ecosystem from metals, the levels and distribution of As, Hg, Cr, Co, Ni, Cu, Zn, Cd, Pb, Mn, V, Sn, Sb, Li and Be in various layers of soil from an e-waste recycling area in Guiyu, China were investigated. The extent of pollution from the metals in soil was assessed using enrichment factors (EFs) and the Nemerow pollution index (P N ). To determine the metals' integrated potential ecological risks, the potential ecological risk index (RI) was chosen. The concentrations of Hg, Ni, Cu, Cd, Pb, Sn and Sb were mainly enriched in the topsoil. EF values (2-5) of the elements Hg, Co, Ni, Zn, Sn, Li and Be revealed their moderate enrichment status in the topsoil, derived from e-waste recycling activities. P N presented a decreasing trend in different layers in the order topsoil (0-20 cm) > deep soil (100-150 cm) > middle soil (50-100 cm) > shallow soil (20-50 cm). With higher potential ecological risk factor (E(i)), Hg and Cd are the main contributors to the potential ecological risk. With respect to the RI, all the values in soil from the study area exceeded 300, especially for the soil at sites S2, S4, S5, S7 and S8, where RI was greater than 600. Therefore, immediate remediation of the contaminated soil is necessary to prevent the release of metals and potential ecological harm.

Challenges in legislation, recycling system and technical system of waste electrical and electronic equipment in China

Waste electrical and electronic equipment (WEEE) has been one of the fastest growing waste streams worldwide. Effective and efficient management and treatment of WEEE has become a global problem. As one of the world's largest electronic products manufacturing and consumption countries, China plays a key role in the material life cycle of electrical and electronic equipment. Over the past 20 years, China has made a great effort to improve WEEE recycling. Centered on the legal, recycling and technical systems, this paper reviews the progresses of WEEE recycling in China. An integrated recycling system is proposed to realize WEEE high recycling rate for future WEEE recycling.

"Control-alt-delete": rebooting solutions for the E-waste problem

A number of efforts have been launched to solve the global electronic waste (e-waste) problem. The efficiency of e-waste recycling is subject to variable national legislation, technical capacity, consumer participation, and even detoxification. E-waste management activities result in procedural irregularities and risk disparities across national boundaries. We review these variables to reveal opportunities for research and policy to reduce the risks from accumulating e-waste and ineffective recycling. Full regulation and consumer participation should be controlled and reinforced to improve local e-waste system. Aiming at standardizing best practice, we alter and identify modular recycling process and infrastructure in eco-industrial parks that will be expectantly effective in countries and regions to handle the similar e-waste stream. Toxicity can be deleted through material substitution and detoxification during the life cycle of electronics. Based on the idea of "Control-Alt-Delete", four patterns of the way forward for global e-waste recycling are proposed to meet a variety of local situations.

Waste management of printed wiring boards: a life cycle assessment of the metals recycling chain from liberation through refining

Due to economic and societal reasons, informal activities including open burning, backyard recycling, and landfill are still the prevailing methods used for electronic waste treatment in developing countries. Great efforts have been made, especially in China, to promote formal approaches for electronic waste management by enacting laws, developing green recycling technologies, initiating pilot programs, etc. The formal recycling process can, however, engender environmental impact and resource consumption, although information on the environmental loads and resource consumption is currently limited. To quantitatively assess the environmental impact of the processes in a formal printed wiring board (PWB) recycling chain, life cycle assessment (LCA) was applied to a formal recycling chain that includes the steps from waste liberation through materials refining. The metal leaching in the refining stage was identified as a critical process, posing most of the environmental impact in the recycling chain. Global warming potential was the most significant environmental impact category after normalization and weighting, followed by fossil abiotic depletion potential, and marine aquatic eco-toxicity potential. Scenario modeling results showed that variations in the power source and chemical reagents consumption had the greatest influence on the environmental performance. The environmental impact from transportation used for PWB collection was also evaluated. The results were further compared to conventional primary metals production processes, highlighting the environmental benefit of metal recycling from waste PWBs. Optimizing the collection mode, increasing the precious metals recovery efficiency in the beneficiation stage and decreasing the chemical reagents consumption in the refining stage by effective materials liberation and separation are proposed as potential improvement strategies to make the recycling chain more environmentally friendly. The LCA results provide environmental information for the improvement of future integrated technologies and electronic waste management.

Disposing and recycling waste printed circuit boards: disconnecting, resource recovery, and pollution control

Over the past decades, China has been suffering from negative environmental impacts from distempered e-waste recycling activities. After a decade of effort, disassembly and raw materials recycling of environmentally friendly e-waste have been realized in specialized companies, in China, and law enforcement for illegal activities of e-waste recycling has also been made more and more strict. So up to now, the e-waste recycling in China should be developed toward more depth and refinement to promote industrial production of e-waste resource recovery. Waste printed circuit boards (WPCBs), which are the most complex, hazardous, and valuable components of e-waste, are selected as one typical example in this article that reviews the status of related regulations and technologies of WPCBs recycling, then optimizes, and integrates the proper approaches in existence, while the bottlenecks in the WPCBs recycling system are analyzed, and some preliminary experiments of pinch technologies are also conducted. Finally, in order to provide directional guidance for future development of WPCBs recycling, some key points in the WPCBs recycling system are proposed to point towards a future trend in the e-waste recycling industry.