Plastic Fraction Research Articles

Enrichment Methods for Metal Recovery from Waste from Electrical and Electronic Equipment: A Brief Review

The growing global demand for minerals and metals, coupled with fluctuations in pricing and market disruptions, has emphasised the critical role of these resources in sustaining the global economy. Waste from Electrical and Electronic Equipment (WEEE) has emerged as a promising source of raw materials, particularly for metal recycling and the valorisation of plastic fractions. In 2022, approximately 62 million metric tons of e-waste were generated worldwide, with projections indicating a rise to 74 million metric tons by 2030. Despite the significant volume of WEEE, only 17.4% was collected and recycled, which reveals a considerable opportunity for resource recovery. This review highlights the composition of metals in WEEE, which includes valuable precious metals, such as gold, silver, and palladium, alongside base metals, such as copper and aluminium. The review also discusses current methodologies for metal recovery and focuses on mechanical size-reduction techniques and various physical separation methods, including a shaking table, magnetic, electrostatic, and eddy current separation, flotation, and the use of a hydrocyclone. These technologies play a vital role in enhancing recovery efficiencies, thereby contributing to sustainable practices in the recycling industry. Thus, the works evaluated in this paper reveal the possibility of recovering more than 90 wt.% of precious (Ag, Au, Pd, Pt) and main metals (Cu, Sn, Al, Fe, Ni) by a combination of these mechanical size-reduction and physical separation methods.

Macro- and micro-plastic accumulation in soils under different intensive farming systems: A case study in Quzhou county, the North China Plain

The macroplastics (MaPs) and microplastics (MiPs) polluting agricultural soils raise great concerns. Unfortunately, scientists know little about the occurrence of MaPs/MiPs in soil among different farming systems. In this study, we analyzed MaPs/MiPs in soils (0–30 cm) collected from six different farming systems (wheat-maize rotations, cotton, vegetables, permanent orchards, greenhouses with and without mulching) in Quzhou county, the North China Plain, by using fluorescence microscope and micro-Fourier transform infrared spectroscopy. The results showed that the abundance of MaPs and MiPs ranged from 0.2 to 46.8 kg ha−1, and 4.1 × 103–3.7 × 104 items kg−1, respectively. The prominent colors of the MaPs were white and black. The predominant shape, size and chemical composition of soil MiPs were fragments (45–62%), <1 mm (98–99%), and polyethylene (38–43%), respectively. MaPs were mainly detected in the 0–10 cm soil layer. MiP abundance in the 0–10 cm soil layer was significantly higher than that in the 20–30 cm soil layers among different farming systems, except for the fields with wheat-maize rotations and permanent orchards (p < 0.05). Overall, cotton fields showed the highest MaP and MiP abundance, followed by vegetable fields and orchards. Redundancy analysis revealed that tillage practices and plastic film management greatly influence the size distribution of MiPs. A strong negative correlation between large-sized plastic fractions (0.2–1 mm) and tillage frequency was tested while the years of application of plastic films and the abundance of plastic residues showed a strong positive correlation with small-sized plastic fractions (<0.2 mm). Our findings conclude that agricultural mulch films are an important source of MaPs and MiPs in agricultural soil and distributions are strongly influenced by agricultural management practices and farming systems. Further studies should take farming systems and farming practices into account, thereby exploring the potential mechanisms of plastic fragmentation and granularization in agricultural soil.

Preliminary Research to Assess the Possibility of Grinding Selected Plastics Using Crushers.

This study aims to investigate the effect of the shredding machine used on the recyclability of plastic fractions after primary crushing. This work presents a method for producing aggregates that has yet to be used in the plastics industry. This study included crushing of polymethylmethacrylate (PMMA), polyamide (PA-6), acrylonitrile butadiene-styrene (ABS), polycarbonate (PC), polystyrene (PS), and polypropylene (PP) waste in a jaw, a hammer, and a cone crusher. An analysis of the grain composition was carried out to characterize the obtained crushing products. The influence of feed size on the grain composition of the product and, only on the jaw crusher, the influence of the material used on the parameters of the crushing process was studied. This paper proposes a method to evaluate the grain composition and a way to assess plastic shredding capabilities based on machine kinematics and mechanical properties of a given material.

Carbonization of Refuse-Derived Fuel Pellets with Biomass Incorporation to Solid Fuel Production

In this work, dry carbonization (DC) and hydrothermal carbonization (HTC) of refuse-derived fuel (RDF) pellets were conducted to evaluate the physical, chemical, and fuel properties of the produced chars. In the dry carbonization tests, biomass sawdust was incorporated in different proportions on the samples to minimize agglomeration caused by the melting of the plastic fraction. The experiments were carried out in a temperature of 400 °C (DC) and 250–300 °C (HTC), in a residence time of 30 min. The respective chars and hydrochars were characterized according to their mass yield, apparent density, proximate, elemental, and mineral composition, chlorine content, high heating value, thermogravimetric profile, and surface functional groups. The results showed that the dry carbonization of RDF pellets with biomass incorporation, followed by a washing step, resulted in the production of chars with improved properties such as higher fixed carbon and higher heating value (HHV) (25–26 MJ/kg) and lower ash and chlorine content. Additionally, the HTC experiments demonstrated that hydrochars showed improved properties without the need for biomass addition and washing, however, with no significant difference in the HHV (20–21 MJ/kg). Therefore, DC of RDF pellets with 10% biomass incorporation seems to be a promising option to overcome the constraints of RDF utilization as an alternative fuel.

A Business Management Model in the Circular Economy: Technological Solutions for Plastic Recycling

Objectives: this article develops a model for managing business processes in a circular economy using technologies for plastic recycling. Theoretical Framework: The theoretical idea and basis of the article consists in the development of project management methodology, process approach in the closed-loop economy, development of methods and economic tools aimed at effective resource management taking into account waste reduction and increased reuse of plastic fractions in Municipal Solid Waste (MSW). The application of digital technologies and solutions in the context of business process management in the field of plastics recycling will be substantiated, which will allow to identify new opportunities and reserves for optimising business processes in this field, increasing the efficiency of resource use, improving the environment and reducing costs. Method: the work uses a project approach, a process approach, digital modeling methods, and the “polluter pays” method. To implement the process approach, it is proposed to use the concept of Business Process Management (BPM). Competent business process management allows the company to react quickly to changing market conditions and customer orientation. Digital modelling in this paper means the representation of actions in the form of business processes in the organisation of solid waste management, the 'polluter pays' method means the economic assessment and accounting of environmental damage in waste management in the costs of business processes. Results and Discussion: The results of the study can be used to introduce the process approach to plastics recycling in individual regions and countries for the development of a green economy. According to the estimates of the authors, the optimisation and cost reduction of business processes, taking into account the environmental factor and the increase of the revenue part of the project from the reuse and inclusion in the economic turnover of plastic waste recycling products on the scale of the considered city (population of 1800 thousand people, area of 2856 ha, 18.14 tonnes of plastic waste accumulated per day) will reduce the costs of business process management by more than 200 thousand euros. Research Implications: the results of the study can be used to justify projects for the processing and recycling of solid municipal waste, including plastic waste, to introduce environmentally friendly production, to reduce the negative impact on the environment, to develop a process approach to the organisation of all activities for the collection of plastic waste in the city, district. In addition, the application of the proposed approach allows to obtain economic benefits for companies through the sale of secondary resources for the processing of plastic waste, as well as to reduce the negative impact on the environment. Originality/ Value: The originality of the research and its value lies in a new scientific formulation of the problem of reducing environmental pollution from plastic waste through the use of business processes in the field of plastic recycling and digital solutions, as well as the possibility of practical application of the results obtained in the field of green economy.

A Viability Study of Thermal Pre-Treatment for Recycling of Pharmaceutical Blisters

Pharmaceutical packaging is one of the most used packaging types which contains aluminum and plastics. Due to increasing amounts of waste and rising environmental concerns, recycling approaches are being investigated. Since blisters usually contain a balanced amount of plastics and metals, most of the approaches focus on recycling only one material. Therefore, more sustainable recycling approaches which recover both plastic and aluminum fractions are needed. This study investigates the thermal behavior and degradation mechanisms of plastic-rich and aluminum-rich pharmaceutical blisters using various analytical techniques. Structural characterization revealed that plastic-rich blisters have a thicker profile with plastic and aluminum layers, while aluminum-rich blisters consist of plastic layers between aluminum sheets. Thermal degradation analysis showed two main stages for both types: plastic-rich blisters (polyvinyl chloride) exhibited significant weight loss and long-chain hydrocarbon formation between 210 and 285 °C, and aluminum-rich blisters (polyamide/nylon) degraded from 240 to 270 °C. Differential Scanning Calorimetry and Fourier Transform Infrared Spectroscopy analyses confirmed the endothermic behavior of such a transformation. The gas emissions analysis indicated an increased formation of gasses from the thermal treatment of plastic-rich blisters, with the presence of oxygen leading to the formation of carbon dioxide, water, and carbon monoxide. Thermal treatment with 5%O2 in the carrier gas benefited plastic-rich blister treatment, reducing organic waste by up to 80% and minimizing burning risk, leveraging pyrolytic carbon for protection. This method is unsuitable for aluminum-rich blisters, requiring reduced oxygen or temperature to prevent pyrolytic carbon combustion and aluminum oxidation.

Physicochemical properties and energy potential of combustible municipal solid waste from Lomé, Togo

ABSTRACT This study aims to fill the knowledge gap regarding the physicochemical properties of combustible municipal solid waste (CMSW) from Lomé under its wet and dry seasons. Over both seasons, waste characterisation campaigns were conducted followed by the proximate and ultimate analyses of CMSW samples composed of putrescible, miscellaneous combustible (MC), plastic, textile, and paper & cardboard fractions. In addition, the energy and oxide contents from CMSW were measured with a calorimeter and X-Ray Fluorescence analyser respectively. The results showed that putrescible had the highest weight proportion with significant differences among waste fractions over wet and dry seasons (p-value 1.90E–07 < 0.05). On average, textile and plastic achieved the highest volatile and lowest fixed carbon contents respectively, while plastic achieved the highest ash content. The highest carbon, hydrogen, and oxygen content was from textile, while the highest nitrogen-sulphur content was from plastic. The estimated energy potential was in the order of plastic (2.88 MJ/kg) > putrescible (2.73 MJ/kg) > textile (0.86 MJ/kg) > MC (0.67 MJ/kg) > paper & cardboard (0.18 MJ/kg). The content of silicon dioxide (75.88 wt%) and manganese oxide (0.02 wt%) were the highest and lowest from plastic, respectively. Therefore, CMSW showed important energy value though highly contaminated by fines.

Self-formation of dual-phase nanocomposite Zr–Cu–N coatings based on nanocrystalline ZrN and glassy ZrCu

A novel type of nanocomposite Zr–Cu–N material based on hard nanocrystalline ZrN and amorphous glassy ZrCu was prepared by atom-by-atom deposition using reactive magnetron co-sputtering. The elemental composition of the coatings was systematically controlled over a wide range, so that the stoichiometry of both phases was the same in all coatings and only phase fractions varied. Experimental results obtained using X-ray diffraction and electron microscopies were complemented by thirteen ab-initio simulations for the same coating compositions. We found that the structure of the as-deposited Zr–Cu–N coatings undergoes a gradual transition from an amorphous to nanograined and finally to nanocolumnar structure. When ZrN fraction exceeds 20 mol.%, both phases exhibit the tendency for spontaneous segregation even without heating, forming a heterogenous dual-phase nanocomposite structure. At approximately 50 mol.% ZrN, the ZrN nanocrystals enveloped by a relatively thin amorphous ZrCu phase reach an optimum size (3–5 nm), resulting in a maximum enhancement of hardness by 38 % compared to the rule of mixture. For ZrN fractions > 80 mol.%, hardness and plastic work fraction follow the trend proposed by the rule of mixture and the coatings with a lower hardness but a higher plasticity compared to the ZrN coating are prepared.

Life cycle assessment of recycling metallised food packaging plastics using mechanical, thermal and chemical processes

Single treatment of metallised food packaging plastics waste (MFPW) has shown disappointing results with recycling rate <20 % due to its complex structure consisting of 10 % aluminium (Al) and 90 % mixed plastic films made of PE, PP, PS, PET, etc. Besides, it is generating many emissions and residues that must be landfilled making it difficult to integrate them into the circular economy. Therefore, a multi-stage recycling (MSR) approach has recently been developed using several sequential mechanical, thermal and chemical processes to recover energy and Al from MFPW with additional revenue for recycling plant operators. The thermal treatment helps to decompose the plastic fraction into wax or oil, gaseous, and solid residue (SR) composed of Al and coal, while the mechanical process can be used as a pre-treatment of MFPW feedstock and SR. Finally, the chemical treatment (leaching and functionalization) can be used to extract Al from SR and to refine coal into carbon microparticles (CPs), respectively. In order to investigate the environmental performance of the proposed MSR system, this research was developed. The investigation was performed using SimaPro life cycle analysis (LCA) tool according to ISO 14040/44 Standards and the impact assessment method is ReCiPe 2016. Five different scenarios were proposed in the constructed LCA layout, namely, conversion of MFPW to a) wax and gas (pyrolysis), b) wax, gas, and aluminium chloride (AlCl₃) (pyrolysis and leaching), c) wax, gas, AlCl₃, and CPs (pyrolysis, leaching, and functionalization), and d) oil, gas, AlCl₃, and CPs (catalytic pyrolysis, leaching, and functionalization). Besides, the oil produced from catalytic pyrolysis is used for generation of electricity (scenario e). The results showed that wax and gas recovery scenario (a) has better environmental potential and environmental benefits compared to incineration practice. The results did not change much after extraction of Al and CPs (scenario b, c), with a few increasing by 2–4% in the total score. While a lot of environmental burdens from upgrading and utilization (Scenario d, e) were recorded, reaching 79 % due to the huge amount of the catalyst was used. Thus, MSR systems have bigger environmental benefits, however, the chemical and catalytic processes still need to be further improved to reduce the effect of terrestrial acidification.

Realistic Nanoplastics Induced Pulmonary Damage via the Crosstalk of Ferritinophagy and Mitochondrial Dysfunction.

The smaller size fraction of plastics may be more substantially existing and detrimental than larger-sized particles. However, reports on nanoplastics (NPs), especially their airborne occurrences and potential health hazards to the respiratory system, are scarce. Previous studies limit the understanding of their real respiratory effects, since sphere-type polystyrene (PS) nanoparticles differ from NPs occurring in nature with respect to their physicochemical properties. Here, we employ a mechanical breakdown method, producing NPs directly from bulk plastic, preserving NP properties in nature. We report that among four relatively high abundance NP materials PS, polyethylene terephthalate (PET), polyvinyl chloride (PVC), and polyethylene (PE) with a size of 100 nm, PVC induced slightly more severe lung toxicity profiles compared to the other plastics. The lung cytotoxicity of NPs is higher than that of commercial PS NPs and comparable to natural particles silicon dioxide (SiO2) and anatase titanium dioxide (TiO2). Mechanistically, BH3-interacting domain death agonist (Bid) transactivation-mediated mitochondrial dysfunction and nuclear receptor coactivator 4 (NCOA4)-mediated ferritinophagy or ferroptosis are likely common mechanisms of NPs regardless of their chemical composition. This study provides relatively comprehensive data for evaluating the risk of atmospheric NPs to lung health.

An Innovative Magnetic Density Separation Process for Sorting Granular Solid Wastes

Solid waste sorting is an important pre-treatment in recycling to improve the efficiency of material recovery and reduce costs. Motivated by the PEACOC project on metal recovery from solid wastes, an innovative magnetic density separation (MDS) process has been developed for solid waste sorting. It has intrinsic advantages over conventional gravity separation technologies and the previously industrialized MDS process. The new MDS process applies an inclined planar magnet and a horizontal basin containing a static magnetic fluid as the separation medium. A particle sliding phenomenon is identified as a feature that could help the separation. Experiments have been carried out to demonstrate the role of the MDS in concentrating valuable metals in shredded PCBAs and reducing metallic contaminants in plastic fractions of shredded wires. A pilot scale facility is introduced to show the design to achieve continuous production and to reduce the consumption of ferrofluid.

Combustion characteristics of refuse-derived fuel pellets having varying plastic compositions.

The plastic fraction of refuse-derived fuel (RDF) pellets influences fuel's physico-chemical, and mechanical properties, which in turn might affect the combustion behavior of RDF. In the present study, the combustion behavior of different plastic fraction-simulated RDF pellets is reported. The simulated pellets were prepared based on the Indian commercial RDF composition. Initially, the plastic content varied from the existing fraction in Indian commercial RDF, i.e., 35% (RDF-1), to a lower plastic content of 5% (RDF-2). Physico-chemical characterization showed that a higher plastic fraction in RDF-1 reduces its pellet density by 25% as compared to RDF-2. The changes in RDF physico-chemical properties due to plastic variation are reflected in the RDF conversion process. Single-particle and packed-bed studies concluded that the lower density for higher plastic RDF-1 leads to lower conversion times (36%), and higher flame front speed (11%), which are desirable conditions for faster conversion. However, packed-bed studies also showed limitations regarding the utilization of high plastic RDF as RDF-1 has a narrow range of operating air mass flux due to the early advent of convective cooling of the bed. Finally, considering the constraints associated with the utilization of high plastic fraction (~ 35%) RDF and to maximize the effective utilization of plastic in RDF, a workable plastic fraction of 15% in RDF was proposed and tested for its combustion properties. RDF with 15% plastic showed faster conversion, higher flame front speed, and a wider range of operating air mass flux before the advent of convective cooling of the bed.

Hydrothermal Co-Liquefaction of Food and Plastic Waste for Biocrude Production

In this study, hydrothermal co-liquefaction of restaurant waste for biocrude production was conducted. The feedstock was resembled using the organic fraction of restaurant waste and low-density polyethylene, polypropylene, polystyrene, and polyethylene terephthalate, four plastic types commonly present in municipal solid waste. Using design of experiment and a face-centered central composite design, three factors (feedstock plastic fraction, temperature, time) were varied at three levels each: feedstock plastic fraction (0, 0.25, 0.5), temperature (290 °C, 330 °C, 370 °C), and reaction time (0 min, 30 min, 60 min). The literature reports positive synergistic interactions in hydrothermal co-liquefaction of biomass and plastics; however, in this work, only negative synergistic interactions could be observed. A reason could be the high thermal stability of produced fatty acids that give little room for interactions with plastics. At the same time, mass might transfer to other product phases.

Resource recovery from soiled sanitary napkin waste-a state-of-the-art review.

With ever-improving social and medical awareness about menstrual hygiene in India, the demand for sanitary napkins has increased significantly. The utilization of high-quality and environment-friendly raw materials to produce these pads is further supporting the growth of the market. However, with improving demand and usage, the need for proper disposal techniques becomes more relevant, since all of these pads get contaminated with human blood which makes them a biohazard and can cause significant damage to human health and the environment. One sanitary pad takes around 800years to degrade naturally and the plastic and super absorbent polymers (SAPs) in sanitary pads are non-biodegradable and can take multiple decades to degrade. Waste management technologies such as pyrolysis, gasification, and resource recovery can be adopted to manage tons of sanitary waste. Currently, sanitary waste treatment mainly focuses on landfilling, incineration, and composting, where biohazard wastes are mixed with tons of solid waste. Disposable sanitary pads have a high carbon footprint of about 5.3kg CO2 equivalent every year. Innovative solutions for sanitary pad disposal are discussed in the manuscript which includes repurposing of derived waste cellulose and plastic fraction into value-added products. Future aspects of disinfection strategies and value addition to waste cellulose recovered from napkins were systematically discussed to promote a circular economy.

Capillary Suction Properties of Mortar Made with Recycled Plastic Aggregates Elaborated from Waste Electrical and Electronic Equipment

It is possible to revalue the plastic fraction from WEEE using it as a recycled aggregate (RA) in cement mortars. However, this feasibility depends on elaborating a granular material via a core-shell strategy to stabilize the potential contaminants. The core is a plastic particle, and the shell is a cement, fillers, and activated carbon mixture. Due to the hydrophilic characteristics of the shell and the presence of interstitial sites generated by the use of the RA, it is necessary to study the wetting properties of these mortars. This article presents the results of capillary suction and contact angle studies of mortars made with RA having different shell compositions. The capillary suction of the latter is higher than in traditional mortars, which limits their use for structures exposed to water and environmental agents but opens the possibility of new uses in permeable concrete or for the manufacture of building components.

The effect of particle geometry (size & shape) on the recovery of gold and copper metallic particles from end-of-life random access memory cards by flotation

Since Random Access Memory (RAM), one of the main parts of computers contains a remarkable quantity of precious metals, applying flotation at the pre-concentration stage to recycle these metals can result in a more cost-effective, user-friendly, and environmentally friendly process compared to direct chemical methods. While the significance of physical characteristics like particle size and shape in the flotation process is well established, the impact of particle shape in the flotation process utilized in the recycling of end-of-life (EoL) RAMs hasn’t yet been thoroughly investigated. To fill this gap, a two-stage coarse flotation approach is used for the selective recovery of plastic and valuable metallic particles for sustainable development. The particle geometry of metallic particles recovered by flotation was characterized by axis measurement on the images by optical microscope that allows us to distinguish particles of different sizes and colors that make up the sample and evaluated in terms of particle size distribution (PSD), elongation (E) and roundness (R) parameters. The results showed that after the plastic fraction is effectively removed, it is possible to produce pre-concentrated products with high metal content (more than 50 % Cu content at the 1st stage and 1800 g/t Au content at the 2nd stage using 900 g/t KAX) in an economical and environmentally friendly way. Thus, it was concluded that the gold and copper metallic particles in the reduced-size EoL RAM cards could be easily floated by attaching them to the air bubble with the help of the collector, thanks to their flat shape.

Impact of Metal Impregnation of Commercial Zeolites in the Catalytic Pyrolysis of Real Mixture of Post-Consumer Plastic Waste

This work reports the study of the catalytic pyrolysis of rejected plastic fractions collected from municipal solid waste whose mechanical recovery is not plausible due to technical or poor conservation issues. The chemical recycling using catalytic pyrolysis was carried out over commercial zeolites formulas, i.e., HY and HZSM-5, in which Ni or Co metals were deposited at two different loadings (1 and 5%, wt.). The presence of these transition metals on the zeolitic supports impacted the total production of compounds existing in the liquid oil. The samples were characterized in terms of structural, chemical, and morphologic properties, and the production of different fuel fractions (gasoline, light cycle oil, and heavy cycle oil) was correlated with a combined parameter defined as a ratio of Acidity/BET area.

On the cutting-edge of non-recyclable plastic waste valorization: From pyrolysis char to nitrogen-enriched activated carbon for landfill biogas upgrading

The rejected fraction of post-consumer plastics collected by mechanical sorting is a source of chemical recycling by processes such as pyrolysis, promoting the circular economy. The char residue produced in this process has been valorized, reinforcing the introduction in the consumption chain, as an adsorbent aimed at the upgrading of a biogas stream. The char was activated with KOH (496 m2 g−1) and the surface of the material was enriched with nitrogen groups (6% wt. by XPS) to raise the CO2 uptake. KOH and urea were used following different strategies, demonstrating that sequential activation and modification is the most efficient approach. Although the surface area was decreased after N insertion, i.e. from 497 to 389 m2 g−1, the CO2 uptake was raised. Specifically, comparing the CO2 uptake per micropore surface was considerably improved after urea functionalization (0.351 vs 0.235 mg m−2). The selectivity was not considerably modified, but the isosteric adsorption heat of the urea-modified sample was higher than the bare one. The behavior in the dynamic tests was studied in fixed-bed column, assessing the effect of temperature, and inlet CO2/CH4 concentration, individually and in mixtures. There was no appreciated loss of performance in the adsorption-desorption cycles. The urea-modification in a two-pot synthesis process proved a better performance in dynamic tests if compared to the non-modified activated char. This work sheds insights into the feasibility of the recycling of plastic residues giving to new added-value materials such as functionalized carbonaceous adsorbents, promoting a circular economy basis.

Thermal pyrolysis of a real plastic sample from small WEEE and characterization of the produced oil in view of fuel or feedstock uses

The possibilities of valorizing by pyrolysis a plastic fraction from small waste from electrical and electronic equipment (WEEE-R4) rejected by a material recovery facility have been assessed. The characterization revealed that WEEE-R4 was mainly composed of acrylonitrile–butadiene–styrene (ABS) and blends of polycarbonate (PC)-ABS (75 and 25 wt%, respectively) and had good physicochemical properties as feed for pyrolysis processes: high values for volatile matter (95 wt%) and low heating value (LHV, 35 MJ/kg) and low ash and moisture content (2.5 and 0.33 wt%, respectively). On the contrary, the high content of heteroatoms, in particular Br from brominated flame retardants, arose as source of concern. Thermal analysis coupled with evolved gas Fourier transform Infrared (FTIR) spectroscopy showed that WEEE-R4 degraded in two steps in the range 310–460 °C and mainly to the monoaromatic compounds phenol and styrene. Thermal pyrolysis at 400 °C was carried out in a bench-scale reactor and the yields of the products were 18 wt% solids, 58 wt% light oil, 16 wt% tar and 8 wt% gas. The gaseous fraction was composed mainly of CO2 (60 wt%), originating from the thermal degradation of PC. After removing CO2, the gas had a good LHV (32.5 MJ/kg) such to contribute for the 66 % to the energy required for the pyrolysis process of WEEE-R4. The properties of the light oil were evaluated by means of the same standard tests used for commercial fuels or crude oils. The results were interesting but far from the more refined gasoline and diesel oil, with the concentration of nitrogen and bromine even higher than the typical composition of petroleum. Nevertheless, this study shows that pyrolysis followed by a refining treatment such as, distillation is capable of producing monoaromatic hydrocarbon in significant amount (>30 wt%).

Is the assimilation to a solid recovered fuel a viable solution for automobile shredder residues’ management?

Directive 2000/53/EC and the European Circular Economy Package (2018) required the Member States to take all the necessary measures to reach the reuse-recycling goal of 85% for end-of-life vehicles (ELVs). In 2019, Europe achieved 89.6% of reuse-recycling, but most EC countries are still not completely compliant, Italy standing, for example, at only 84.2%. For this reason, actions are necessary to increase reuse-recycling for the waste generated in the operations of ELV shredding and separation, known as automobile shredded residues (ASRs). This study was aimed at assessing if the assimilation of ASRs to a solid recovered fuel (SRF) was a feasible solution. That would allow the waste to lose its status (end-of-waste, EoW), thus increasing the recycling rate. The assimilation of ASRs to SRFs requires the compliance with a series of parameters, namely net calorific value (NCV), content of chlorine (Cl), mercury (Hg) and selected heavy metals. The above-mentioned parameters were analyzed in the principal ASR fractions, namely textile, plastic and foam rubber, found in the samples collected during four sampling campaigns (2017–2021) performed at the same ELV treatment plant. Notwithstanding the great variability observed in the four samples, the results of the analyses revealed that the three fractions were compliant with NCV, Cl and Hg content. Conversely, the heavy metals' content was found a more critical parameter, in fact only the plastic fraction was suitable for SRF assimilation. Textiles presented criticality for the content of copper (Cu), nickel (Ni) and antimony (Sb). The heavy metals' contamination of foam rubber was found to be strongly related to particles' dimensions. A model which put particle size and metals’ content into relationship was developed and validated. Removing particles of <40 mm significantly improved the quality of the material, however the content of Cu and Ni remained a critical issue for particles up to 200 mm. The SRF assimilation of the plastic fraction would increase the reuse-recycling rate of approx. 2.4–3.3%, thus allowing the achievement of the EC goals concerning the ELV management.