Waste Electrical And Electronic Equipment Plastic Research Articles

Enhancement of recycling system for large WEEE plastics in Korea via material flow analysis (MFA) and hazardous substances assessment

Globally, there is interest in recycling waste electrical and electronic equipment (WEEE) plastics for transition to circular resource society and concern about substances with potential harzard in WEEE. For high-quality recycling of WEEE plastics, it is necessary to find factors that hinder recycling of the entire life of plastics and investigate hazardous substances for recycling safety. In this study, through conducting material flow analysis(MFA), 27 kt of WEEE was collected and only 3.9 % of the production was returned to plastic recycling market. To resolve this gap, further research by related organizations, including updating statistical data on the plastics, is required in addition to consideration for converting unofficial routes into official routes. For the activation of the secondary material recycling market, strict quality control is required, because some samples contained relatively high levels of PBDEs DEHP restricted under law. And it is necessary to monitor of unrestricted substance, TBBPA and Bisphenol A detected at high concentration in WEEE plastic, for the safe recycling of plastic waste.

Recycling Plastics from WEEE: A Review of the Environmental and Human Health Challenges Associated with Brominated Flame Retardants

Waste electrical and electronic equipment (WEEE) presents the dual characteristic of containing both hazardous substances and valuable recoverable materials. Mainly found in WEEE plastics, brominated flame retardants (BFRs) are a component of particular interest. Several actions have been taken worldwide to regulate their use and disposal, however, in countries where no regulation is in place, the recovery of highly valuable materials has promoted the development of informal treatment facilities, with serious consequences for the environment and the health of the workers and communities involved. Hence, in this review we examine a wide spectrum of aspects related to WEEE plastic management. A search of legislation and the literature was made to determine the current legal framework by region/country. Additionally, we focused on identifying the most relevant methods of existing industrial processes for determining BFRs and their challenges. BFR occurrence and substitution by novel BFRs (NBFRs) was reviewed. An emphasis was given to review the health and environmental impacts associated with BFR/NBFR presence in waste, consumer products, and WEEE recycling facilities. Knowledge and research gaps of this topic were highlighted. Finally, the discussion on current trends and proposals to attend to this relevant issue were outlined.

Characterizing plastics from large household appliances: Brominated flame retardants, other additives and density profiles

Large household appliances contain substantial amounts of plastics. At their end of life, these appliances are processed in waste electrical and electronic equipment (WEEE) treatment plants where a mixed plastic fraction is generally obtained after mechanical processing. This paper presents the results of a study conducted to investigate whether the practice of recycling these plastic streams without decontamination can be continued after the introduction of the 1000 mg/kg threshold value for the sum of polybrominated diphenyl ethers (PBDEs) in the 2019 recast of the European POP regulation. 25 samples of shredded mixed plastics from large household appliances were collected and analysed by two independent chemical laboratories with regard to various Brominated Flame Retardants (BFRs), heavy metals and tracers of common plastic additives. Results show that the currently applicable threshold values for recycling regarding heavy metals and BFRs are not exceeded in any of the analysed samples. However, relevant amounts of PBDEs (up to 791 mg/kg), tetrabromobisphenol-A (up to 1470 mg/kg) and antimony (up to 1200 mg/kg) were detected, all of which are currently under consideration for more stringent regulation in the EU. Results further show that due to limitations in analytical precision and representative sampling, the quantification of legacy substances in mixed WEEE plastic fractions is very challenging and the level of confidence with which decisions regarding legal compliance for recycling are taken is limited. It is strongly recommended that these challenges are taken into account when new threshold values are defined in order to enable a clean circular economy.

Ecotoxicity of Plastics from Informal Waste Electric and Electronic Treatment and Recycling.

Plastic materials account for about 20% of waste electrical and electronic equipment (WEEE). The recycling of this plastic fraction is a complex issue, heavily conditioned by the content of harmful additives, such as brominated flame retardants. Thus, the management and reprocessing of WEEE plastics pose environmental and human health concerns, mainly in developing countries, where informal recycling and disposal are practiced. The objective of this study was twofold. Firstly, it aimed to investigate some of the available options described in the literature for the re-use of WEEE plastic scraps in construction materials, a promising recycling route in the developing countries. Moreover, it presents an evaluation of the impact of these available end-of-life scenarios on the environment by means of the life cycle assessment (LCA) approach. In order to consider worker health and human and ecological risks, the LCA analysis focuses on ecotoxicity more than on climate change. The LCA evaluation confirmed that the plastic re-use in the construction sector has a lower toxicity impact on the environment and human health than common landfilling and incineration practices. It also shows that the unregulated handling and dismantling activities, as well as the re-use practices, contribute significantly to the impact of WEEE plastic treatments.

Auto-sorting commonly recovered plastics from waste household appliances and electronics using near-infrared spectroscopy

Abstract The recycling of plastics from Waste electrical and electronic equipment (WEEE) was constrained by the mix of types. Near-infrared (NIR) spectroscopy is suitable for polymer detection, and it is a rapid, non-destructive analysis method that can be applied to automatic on-line sorting system. The NIR spectra of four commonly recovered WEEE plastics, which are polypropylene (PP), polystyrene (PS), acrylonitrile butadiene styrene (ABS), and acrylonitrile butadiene styrene/polycarbonate (ABS/PC) blend, was collected. The flame-retardant ABS showed difference from ABS in NIR spectra. Three classification methods, which are spectral angle mapper (SAM), partial least squares discriminant analysis (PLS-DA) and linear discriminant analysis combined with principal component analysis (PCA-LDA), was tested. And the classification models trained on the virgin plastics have been compared with the models trained on the WEEE plastic to evaluate how these methods perform under limited training data. PLS-DA is one of the most widely used classification method in spectral data analysis, but it had unsuccessful prediction when the training set only included virgin plastics. But the overall prediction accuracy over 99% could be achieved by the other two whether the training set was the spectra of virgin plastics or WEEE plastics. In general, NIR spectroscopy has the competency of separating WEEE plastics. Finally, an automatic on-line sorting system was designed specifically for the large plastic segments from household appliances and electronics.

Pyrolysis of WEEE plastics using catalysts produced from fly ash of coal gasification

Catalytic pyrolysis of thermoplastics extracted from waste electrical and electronic equipment (WEEE) was investigated using various fly ash-derived catalysts. The catalysts were prepared from fly ash by a simple method that basically includes a mechanical treatment followed by an acid or a basic activation. The synthesized catalysts were characterized using various analytical techniques. The results showed that not treated fly ash (FA) is characterized by good crystallinity, which in turn is lowered by mechanical and chemical treatment (fly ash after mechanical and acid activation, FAMA) and suppressed almost entirely down to let fly ash become completely amorphous (fly ash after mechanical and basic activation FAMB). Simultaneously, the surface area resulted increased. Subsequently, FA, FAMB and FAMA were used in the pyrolysis of a WEEE plastic sample at 400°C and their performance were compared with thermal pyrolysis at the same temperature. The catalysts principally improve the light oil yield: from 59 wt.% with thermal pyrolysis to 83 wt.% using FAMB. The formation of styrene in the oil is also increased: from 243 mg/g with thermal pyrolysis to 453 mg/g using FAMB. As a result, FAMB proved to be the best catalyst, thus producing also the lowest and the highest amount of char and gas, respectively. Open image in new window

A study on the environmental aspects of WEEE plastic recycling in a Brazilian company

Purpose The high consumption of electrical and electronic equipment motivated by the rapid technological advances seen over the years has lead to an increase in the generation of waste electrical and electronic equipment (WEEE). Such residues contain various dangerous substances and therefore deserve special attention. To that end, the Brazilian Policy on Solid Waste has provided guidelines on integrated and solid waste management, such as consumer electronics, aiming at their appropriate disposal and treatment through reverse logistics. In this context, the present work focuses on studying the recycling of some WEEE plastics.

Sustainable and Selective Separation of PVC and ABS from a WEEE Plastic Mixture Using Microwave and/or Mild-Heat Treatment with Froth Flotation.

This study reports simple, selective, and sustainable separation of chlorinated plastic (polyvinyl chloride, PVC) and acrylonitrile butadiene styrene (ABS) containing brominated flame retardants (BFRs) from mixed waste electrical and electronic equipment (WEEE) plastics using microwave and/or mild-heat treatment. Microwave treatment after plastic coating with powdered activated carbon (PAC) selectively increased the hydrophilicity of the PVC surface, which facilitated PVC separation (100% recovery and purity) from the WEEE plastic mixture under the optimum flotation conditions. A further mild-heat treatment for 100 s facilitated selective separation with the highest recovery and purity (100%) of PAC-coated ABS containing BFRs from the remaining plastic mixture due to selective formation of a twisted structure with a lower density than water and the untreated ABS. Mild-heat treatment only of PAC-coated WEEE plastic mixture resulted in successful recovery of (100%) the ABS and PVC. However, the recovered PVC had slightly reduced purity (96.8%) as compared to that obtained using the combined heat and microwave treatments. The combination of both treatments with flotation facilitated selective and sustainable separation of PVC and ABS from WEEE plastics to improve their recycling quality.

The presence and leachability of antimony in different wastes and waste handling facilities in Norway.

The environmental behaviour of antimony (Sb) is gathering attention due to its increasingly extensive use in various products, particularly in plastics. Because of this it may be expected that plastic waste is an emission source for Sb in the environment. This study presents a comprehensive field investigation of Sb concentrations in diverse types of waste from waste handling facilities in Norway. The wastes included waste electrical and electronic equipment (WEEE), glass, vehicle fluff, combustibles, bottom ash, fly ash and digested sludge. The highest solid Sb concentrations were found in WEEE and vehicle plastic (from 1238 to 1715 mg kg(-1)) and vehicle fluff (from 34 to 4565 mg kg(-1)). The type of acid used to digest the diverse solid waste materials was also tested. It was found that HNO3:HCl extraction gave substantially lower, non-quantitative yields compared to HNO3:HF. The highest water-leachable concentration for wastes when mixed with water at a 1 : 10 ratio were observed for plastic (from 0.6 to 2.0 mg kg(-1)) and bottom ash (from 0.4 to 0.8 mg kg(-1)). For all of the considered waste fractions, Sb(v) was the dominant species in the leachates, even though Sb(iii) as Sb2O3 is mainly used in plastics and other products, indicating rapid oxidation in water. This study also presents for the first time a comparison of Sb concentrations in leachate at waste handling facilities using both active grab samples and DGT passive samples. Grab samples target the total suspended Sb, whereas DGT targets the sum of free- and other chemically labile species. The grab sample concentrations (from 0.5 to 50 μg L(-1)) were lower than the predicted no-effect concentration (PNEC) of 113 μg L(-1). The DGT concentrations were substantially lower (from 0.05 to 9.93 μg L(-1)) than the grab samples, indicating much of the Sb is present in a non-available colloidal form. In addition, air samples were taken from the chimney and areas within combustible waste incinerators, as well as from the vent of WEEE sorting facility. The WEEE vent had the highest Sb concentration (from <100 to 2200 ng m(-3)), which were orders of magnitude higher than the air surrounding the combustible shredder (from 25 to 217 ng m(-3)), and the incinerator chimney (from <30 to 100 ng m(-3)). From these results, it seems evident that Sb from waste is not an environmental concern in Norway, and that Sb is mostly readily recovered from plastic and bottom ash.

INNOVATIVE TECHNOLOGIES FOR METALS RECOVERY AND PLASTIC VALORIZATION FROM ELECTRIC AND ELECTRONIC WASTE: AN INTEGRATED APPROACH

The increasing diffusion of Hi-tech complex products has raised the attention of scientific community towards their End of Life (EoL) treatment, both in terms of assuring an appropriate disposal, to avoid the dispersion of harmful substances, and at the aim of their exploitation as valuable sources of raw materials. Within this study an integrated approach for waste electrical and electronic equipment (WEEE) end of life treatment is proposed based on the integration of hydrometallurgy for metal recovery and pyrolysis for plastic fraction valorization, with a particular focus on EoL personal computers. An innovative hydrometallurgical process with limited environmental impact for the recycling of added value metals (Au, Ag, Cu, Sn, Pb) from printed circuit boards was developed and thermal technologies were investigated for the valorization of mixed plastic components. The results show metal recovery rates up to 99% and purity grade up to 99%. With reference to plastic valorization, the maximized production up to 95% w/w of both a liquid and gaseous hydrocarbon-based stream to be exploited as a fuel or as source of chemicals was achieved from WEEE plastic fractions.

Formation of PBDD/F from PBDE in electronic waste in recycling processes and under simulated extruding conditions

The increasing volumes of waste electrical and electronic equipment (WEEE) in Europe and developing economies demand for efficient disposal solutions. However, WEEE also contains toxic compounds and, therefore, there is a need for recycling technologies for WEEE that creates revenue without causing environmental harm. Among other fast developing economies, South Africa is tempting to make use of recycled plastic.Brominated flame retardants (BFRs) are additives used to protect plastic materials in electrical and electronic equipment (EEE) against ignition. Some BFRs are known persistent organic pollutants (POPs) and some BFRs can be transformed into highly toxic compounds such as polybrominated dibenzofurans and dioxins (PBDD/Fs).In this study, the contents of critical BFRs, i.e. polybrominated diphenyl ethers, and highly toxic PBDD/Fs were measured in WEEE material from Switzerland and South Africa. The formation of PBDD/Fs has been observed in two South African recycling processes and under controlled laboratory conditions.Total PBDE-contents in the South African and Swiss plastic waste varied between 1×103 and 7×106μgkg−1. A few WEEE plastic fractions exceeded the RoHS limit of 1×106μgkg−1 for PBDEs and thus they could not be used for recycling products without special treatment.The total content of ∑PBDFs was around 1×103μgkg−1. Such contents in materials do not pose a risk for consumer under normal conditions. Workers at recycling plants might be at risk. The measured formation rates of PBDFs were between 2×10−5 and 2×10−4∑PBDE−1min−1.

An analysis of the composition and metal contamination of plastics from waste electrical and electronic equipment (WEEE)

The compositions of three WEEE plastic batches of different origin were investigated using infrared spectroscopy, and the metal content was determined with inductively coupled plasma. The composition analysis of the plastics was based mainly on 14 samples collected from a real waste stream, and showed that the major constituents were high impact polystyrene (42wt%), acrylonitrile–butadiene–styrene copolymer (38wt%) and polypropylene (10wt%). Their respective standard deviations were 21.4%, 16.5% and 60.7%, indicating a considerable variation even within a single batch. The level of metal particle contamination was found to be low in all samples, whereas wood contamination and rubber contamination were found to be about 1wt% each in most samples. In the metal content analysis, iron was detected at levels up to 700ppm in the recyclable waste plastics fraction, which is of concern due to its potential to catalyse redox reactions during melt processing and thus accelerate the degradation of plastics during recycling. Toxic metals were found only at very low concentrations, with the exception of lead and cadmium which could be detected at 200ppm and 70ppm levels, respectively, but these values are below the current threshold limits of 1000ppm and 100ppm set by the Restriction of Hazardous Substances directive.

Thermal processing of plastics from waste electrical and electronic equipment for hydrogen production

Plastic waste from waste electrical and electronic equipment (WEEE) produced from a real-world commercial WEEE recycling centre has been processed using pyrolysis–gasification using a two-stage reaction system to produce hydrogen. In the first stage, the plastic fraction was pyrolysed at 600°C and the evolved pyrolysis gases were passed directly to a second reactor at 800°C and reacted with steam in the presence of a Ni/Al2O3 catalyst. In addition, high impact polystyrene (HIPS) and acrylonitrile–butadiene–styrene (ABS) which were the main components of the WEEE plastic were reacted to compare with the WEEE plastic. The results showed that the introduction of steam and the catalyst increased the yield of hydrogen. Increasing the nickel content in the catalyst also resulted in higher hydrogen yield. The comparison of the results of WEEE with those of HIPS and ABS showed that WEEE plastic was mainly composed of ABS. The catalyst, after reaction, showed significant deposition of coke composed of filamentous and layered type carbon. Overall the novel processing of waste plastic from electrical and electronic equipment using a two stage pyrolysis–gasification reactor shows great promise for the production of hydrogen.

Analysis of products from the pyrolysis of plastics recovered from the commercial scale recycling of waste electrical and electronic equipment

Three plastic fractions from a commercial waste electrical and electronic equipment (WEEE) processing plant were collected and investigated for the possibility of recycling them by batch pyrolysis. The first plastic was from equipment containing cathode ray tubes (CRTs), the second plastic was from refrigeration equipment, and the third plastic was from mixed WEEE. Initially, the decomposition of each of the plastics was investigated using a TGA linked to a FT-ir spectrometer which showed that the CRT plastic decomposed to form aliphatic and aromatic compounds, the refrigerator plastic decomposed to form aldehydes, CO 2, aromatic, and aliphatic compounds, and the mixed WEEE plastic decomposed to form aromatic and aliphatic compounds, CO 2, and CO. Each plastic mixture was also pyrolysed in a batch reactor to determine the halogen and metal content of the pyrolysis products, additionally, characterisation of the pyrolysis oils was carried out by GC–MS and the pyrolysis gases by GC–FID and GC–TCD. It was found that the halogen content of the oils was relatively low but the halogen and metal content of the chars was high. The pyrolysis oils were found to contain valuable chemical products and the pyrolysis gases were mainly halogen free, making them suitable as a fuel.