Plastic Fraction Research Articles

Characterization of municipal solid waste residues for hydrothermal liquefaction into liquid transportation fuels

This paper presents and evaluates a new method for characterising municipal solid waste residues for assessing the performance of thermochemical conversion technologies to produce fuels. The method combines information from three complementary analytical techniques to estimate the quantity of key organic waste fractions and was demonstrated using two commercial waste residues: ‘BRDF’ and ‘Floc’ produced from the mechanical processing of domestic waste. Cellulose content (mostly paper and textiles) is estimated using acid hydrolysis, while thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) are combined to determine the plastics (LDPE and PET) and non-volatile fractions such as lignin of the wastes. High mass balance closures were achieved for both residues, although the nature of the non-volatile fraction was difficult to verify. Hydrothermal liquefaction (HTL) of cellulose rich BRDF (34.0% cellulose) produced much higher biooil yields than Floc (26.8% and 12.2%, respectively), with a cellulose content of only 22.4%. In both cases, most of the plastic and non-volatile waste fractions partitioned into the solid HTL product, representing a potential method for separating the plastic fractions from other waste components. Importantly, this combined waste characterization method can be used for characterization of any municipal waste residue using acid hydrolysis, TGA and FTIR data, providing accurate information about feedstock composition. It enables comparison between different waste valorisation studies of complex waste residues.

Macromolecular Insights into the Altered Mechanical Deformation Mechanisms of Non-Polyolefin Contaminated Polyolefins

Current recycling technologies rarely achieve 100% pure plastic fractions from a single polymer type. Often, sorted bales marked as containing a single polymer type in fact contain small amounts of other polymers as contaminants. Inevitably, this will affect the properties of the recycled plastic. This work focuses on understanding the changes in tensile deformation mechanism and the related mechanical properties of the four dominant types of polyolefin (PO) (linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), high-density polyethylene (HDPE), and polypropylene (PP)), contaminated with three different non-polyolefin (NPO) polymers (polyamide-6 (PA-6), polyethylene terephthalate (PET), and polystyrene (PS)). Under the locally elevated stress state induced by the NPO phase, the weak interfacial adhesion typically provokes decohesion. The resulting microvoids, in turn, initiate shear yielding of the PO matrix. LLDPE, due to the linear structure and intercrystalline links, is well able to maintain high ductility when contaminated. LDPE shows deformation similar to the pure material, but with decreasing ductility as the amount of NPO increases. Addition of 20 wt% PA-6, PET, and PS causes a drop in strain at break of 79%, 63%, and 84%, respectively. The typical ductile necking of the high-crystalline HDPE and PP is strongly disturbed by the NPO phase, with a transition even to full brittle failure at high NPO concentration.

Approximate standards for the generation of class B medical waste at the present stage

Closely related to the development of the healthcare system is the trend toward an increase in medical waste. Updating the indicative standards for the generation of class B medical waste is necessary for the correct operation of all sequential processes for handling medical waste. Predicting the amount of class B waste generation makes it possible to optimize work in medical organizations and reduce risks to the health of staff and patients. In this work, we noted a significant increase in the generation of medical waste of class B in multidisciplinary hospitals and Outpatient clinics in St. Petersburg and the Leningrad Region, as well as an increase in the fraction of plastic in the composition of medical waste, a statistical evaluation of the results was carried out and indicative standards for the formation of medical waste of class B were proposed. data on indicative standards for waste generation in departments are extremely relevant due to the different fractional and morphological composition of waste, an extremely high potential infectious risk (including the spread of multidrug-resistant strains) in a number of them, for example, in intensive care units, hemodialysis, and surgery.

Quantification of Riverbank Macroplastic Contamination in The Lower Citarum River

Plastic waste generation has been increasing over the last decades. Rivers represent complex environments where plastics may be stored and remobilized. Studies on riverine plastic, including riverbank contamination, are still lacking. Riverbank surveys were carried out in the Citarum River, Indonesia, at three river sections in Purwakarta, Karawang, and Muara Gembong in March-April 2021. The aim was to quantify the abundance of plastic waste at different points in the riverbank zone. The sample ‘monolith’ was taken by digging a quadrat of 30x30x10 cm3. All material was then weighed. Three replicates along the length of the bank and three replicates across the bank were taken. The non-plastic fraction was weighed and its composition was estimated. Plastic fraction was classified into categories, counted, and weighed. The result show that plastic litter was found in all monolith ranging from 0.7-301 g of plastic litter per monolith. The largest proportion of plastic contaminant was found in Karawang with 2.85% of plastic in a single monolith and the largest average plastic contaminant was about 0.78% of the total monolith weight, showing that plastic contamination is prevalent. Enhancing waste management, reducing single-use plastics, and plastic recycling are recommended to tackle plastic contamination in the study area.

Recycling of Polyethylene Terephthalate (PET) Bottles in the Logistics Supply Chain – Overview

A great deal of packaging made of PET is observed in logistics supply chains, and the article is mainly concerned with food – bottles. Implementing the EU’s “zero-waste” guidelines implies action on the part of producers of packaging and food for B2C distribution to find new solutions to enable the above-mentioned stakeholders in the logistics supply chain to balance the business mentioned above parties – taking into account environmental protection. The article discusses the tasks and possibilities under the above conditions of a new type of “RECYCLER” companies, which, at the end of the life of PET packaging, i.e. after the foodstuffs in PET bottles have been consumed, produce a recyclate and return it to re-production. In several journals, including, e.g. (Połednik et al. 2016, Topiarzová et al. 2011), respecting good recycling practices – there is an ongoing discussion on the sense of introducing reusable packaging, deposits, etc. This article discusses the barriers to recovery in a multi-level plastics recovery system, with specific reference to the operation of a PET bottle recycling line, and presents a pre-verified concept for a method to increase the efficiency of separating PET bottles from the plastics fraction in a multi-level waste separation system.

Effect of Active Plastic Fine Fraction on Undrained Behavior of Binary Granular Mixtures

Abstract The mechanical behavior of binary granular mixtures strongly depends on their initial packing density, stress level, fine content, particle size distribution, mineralogy, and shape. This r...

Characterization of two types of shale rocks from Guizhou China through micro-indentation, statistical and machine-learning tools

Micro-indentation tests were performed adopting the grid-type of analysis on two types of shale rocks, which are porous natural materials characterized by strong geological structural and microfabric features. Emphasis was placed on understanding the influence and linkage between these microstructural-microfabric characteristics and the mechanical properties obtained from indentation, including hardness, modulus, elastic and plastic deformation fractions, and their anisotropic and heterogeneous distribution. The indentation loading-unloading curve patterns also functioned as a way to explore this linkage besides the global variation in the mechanical properties. Statistical tools and machine learning techniques were further employed in the indentation data analysis, providing a means of quantifying the intricacies involved with the mechanical properties of the shales. The creep behavior of these porous materials was quantified and linked to the anisotropic structure and mechanical properties, providing insights into one of the most complex natural materials, as many researchers have characterized. Opposite to previously published data on transversely isotropic shale rocks with vertical axis of symmetry, especially shales with high clay and organic content, the results in the present study showed higher modulus normal to the bedding planes compared to the parallel direction, which observation was attributed to the low clay (and organic) content of the shales and the possible low depth the shales were obtained. • Hardness and modulus of shale rocks were examined based on microindentation tests. • The results were interpreted and linked to the microstructure and composition of the shales. • Statistical analysis was applied to the data along with machine learning tools. • Anisotropy and the roles of creep in different directions and fissility were highlighted. • Contour maps with spatial variation of properties were developed.

Chemical Recycling of Mixed Plastics in Electronic Waste Using Solvent-Based Processing

Currently, less than 20% of electronic waste (E-waste) produced in the U.S. is recycled. To improve the recycling rate of E-waste, the study aimed to: (1) identify the major plastics found within electronic shredder residue (ESR), (2) design solvents and processing conditions capable of separating out 90% of the plastic in ESR, and (3) estimate the energy efficiency of the solvent-based process developed. Preliminary screening showed 25 wt.% of the ESR was composed of plastics, with two polymers dominating the sorted plastic fraction—polystyrene (PS, 40 wt.%) and acrylonitrile butadiene styrene (ABS, 25 wt.%). Subsequently, solvents and anti-solvents were screened using Hansen Solubility Parameter Theory for PS, ABS, and ESR dissolution. The pre-screening results showed dichloromethane (DCM) and tetrahydrofuran (THF) as the most effective solvents for PS and ABS, with methanol (MeOH) and ethylene glycol (EG) as the most effective anti-solvents. By optimizing the dissolution time and the solvents used, the highest polymer dissolution yield (99 wt.%) was achieved using DCM for 48 h. Both MeOH and EG precipitated 71 wt.% of the polymer fraction of ESR. EG removed more phosphorus containing flame retardants (94 wt.%) than MeOH (69 wt.%). Energy analysis indicated that the solvent-based processes could save 25–60% of the embodied energy for PS and ABS. Characterization showed that the solvent-based processing could preserve the high molecular weight fraction of the polymers while removing flame retardants at the same time. The results from this study prove the potential of solvent-based processing to produce secondary plastic materials from E-waste for cross-industry reuse.

STABILIZATION OF LEACHATE IN AGGREGATES MADE WITH PLASTIC FROM WEEE

A recycled plastic aggregate (RPA) was developed using the core-shell strategy, where the core is the plastic fraction of Waste of Electrical and Electronic Equipment (WEEE) and a cement matrix with stabilizing additives acts as the shell. The amount of brominated flame retardant (mainly tetrabromobisphenol-A) leached in curing water of RPAs was quantified using extraction with an organic solvent and gas chromatography methods (CG-FID). A clear relationship can be established between the characteristics of the stabilizing additive used and the amount of tetrabromobisphenol-A and bisphenol-A leached. The additive used was activated carbon, which in a manufacture scale may be provided by different suppliers with different mesoporous characteristics, which can be easily determined by the iodine number. The analysis proposed can be an effective way to determine if a particular activated carbon can be used as stabilizing additive in the production of RPAs with the developed technology.

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.

Effects of interactions between organic solid waste components on the formation of heavy components in oil during pyrolysis

This study focused on the interaction between organic solid waste (OSW) components on the formation and chemical composition of heavy components (>150 m/z) in OSW-oil. Rice husk (RH) and polypropylene (PP) as typical biomass and plastic fractions in OSW, were co-pyrolyzed at different blend ratios and different temperatures. The heavy components were characterized by FT-ICR MS, UV-F and GC MS. The results indicated that the yield of heavy components in PP-oil was higher than in RH-oil under the same temperature. Heavy hydrocarbons were found in PP-oil, while heavy phenols and heavy lipids existed in RH-oil. Significant interactions occurred at high temperatures (>600 °C). The interactions promoted the heavy components in all the blend-oils, corresponding to an increase of 20–35% compared to the calculated value of the content in PP-oil and RH-oil. At low PP ratio (25PP + 75RH), PP provided hydrogen to the reactive O-containing species in RH, leading to promoted heavy phenols and heavy lipids. At high PP ratio (50PP + 50RH and 75PP + 25RH), large aromatics (>3 rings) increased of 48–111% with respect to the calculated values. Plenty of PP‑hydrogen and a rich oxygen environment provided by RH radicals enhanced the formation of heavy aromatics and heavy PAH.

Cemetery waste as a substream of municipal waste: research and structure of the selective waste collection in Poland

Cemetery waste (CW) constitutes one of the streams of municipal waste (MW). Based on the available data, it can be said that it accounts for about 1% of the mass of MW being generated in Poland. CW management should be carried out selectively. It is estimated that the level of CW selective collection is lower than the average level achieved for MW. This paper presents some solutions concerning the selective collection of CW implemented in selected municipal and denominational cemeteries in Poland. Based on research conducted, the levels of proper separation of glass and biodegradable waste in containers for their selective collection were determined, accordingly as >85% and >80%. Due to the contamination with paraffin residues, the purity of the selectively collected plastic fraction was lower than 20%. The human factor was recognized as the most significant determining efficiency of the selective collection of CW. Therefore, further education of society, as well as promoting good practices in the field of CW management, should be regarded as desirable.

Co-pyrolysis of wood and plastic: Evaluation of synergistic effects and kinetic data by evolved gas analysis-mass spectrometry (EGA-MS)

Co-pyrolysis of biomass and plastics gives rise to synergistic effects that can improve the properties of the resulting bio-oil. In this paper, the co-pyrolysis of lignocellulose (softwoods and hardwoods) and plastic (polyethylene and polystyrene) mixtures at different ratios was investigated by evolved gas analysis-mass spectrometry (EGA-MS). Through the extraction of specific sets of m/z values, we were able to build component-specific thermograms representative of each component of the mixtures. Such thermograms were used to evaluate the presence of synergistic effects by the comparison with the theoretical thermograms. The shift of the peak temperatures and the differences between the integrated area of the two thermograms showed that both biomass and plastic influence the pyrolytic behaviour of the other component. Finally, the KAS model-free isoconversional method was used on component-specific thermograms to determine apparent activation energies of the biomass and plastic fractions.

The effectiveness of legislative and voluntary strategies to prevent ocean plastic pollution: Lessons from the UK and South Pacific

The islands of the South Pacific contribute a fraction of the mis-managed plastics in the world's ocean, yet the region is one of the main recipients of its impacts. Based on expert interviews and a review of current strategies to prevent marine plastic pollution in six countries (Australia, New Zealand, Fiji, Tonga, Vanuatu, United Kingdom), this paper identifies several interventions – legislative, financial, voluntary - which governments, organisations and individuals can learn from. Both voluntary and statutory consumer-based behaviour change campaigns are well developed and somewhat successful in several countries. While sub-national policies do not inhibit progress, they are not optimal. Harmonisation across the territories of federal and devolved systems is beneficial, such as container return schemes, levies, and bans. Vanuatu has displayed high ambition, and the challenges in achieving this serve as a case study. A coordinated global strategy with associated legislation aimed at tackling plastic pollution is critical.

A Study on the Effect of Construction and Demolition Waste (CDW) Plastic Fractions on the Moisture and Resistance to Indentation of Wood-Polymer Composites (WPC)

This paper investigated the moisture and strength properties of wood-polymer composites (WPC), which were made using three different recycled polymers using wood flour as filler. The recycled polymers were acrylonitrile butadiene styrene (ABS), polypropylene (PP), and polyethylene (PE), which were collected from among the construction and demolition waste (CDW) at a local waste management center. The commercial additives, such as a coupling agent and lubricant, were also included in the materials. Composite materials were manufactured with an agglomeration and an extrusion process. Water absorption and thickness swelling properties of composites, based on the recycled ABS and PE, were restricted compared to the recycled PP. The strength properties of WPC were determined with two methods, a traditional Brinell hardness and resistance to indentation. Using an ABS polymer as a matrix in the composite, the moisture and strength properties were improved. The recycled PP polymer caused these properties to be lowered, especially in the case of moisture properties. This study has shown that the method used can affect the measured value of certain properties. In addition, the sorting of recycled polymer fractions is desirable for the appearance of improved properties.

Effect of different waste plastic fractions on the thermal kinetics and microstructural behaviour of bitumen used for bituminous mix

The price of raw polymers used for making most of the waste plastics has confined the implementation of polymer modified bitumen (PMB) only to the major road projects. In view of the same, an attempt to make a PMB by such wastes was considered as a “state-of-art” in this investigation. Therefore, the different proportions of waste plastic fractions were blended with the pristine bitumen and the resulting blend characterized by thermal kinetics analysis, microstructural analysis, and Marshall mix design, respectively. The major findings have predicted the highest thermal stability of the blend was achieved by mixing plastic bags, plastic milk pouches, and plastic cups together in proportion of 2:0.25:1 to virgin bitumen with no thermal decomposition. Further, uniform dispersion of “bee-like structure” in that blend has reflected its homogeneity. Besides, such modified bitumen has elevated the Marshall quotient of the bituminous mix by 16%, which can preferentially be used in the rural roads safely, confirmed by Marshall mix design.

Factors Shaping the Recycling Systems for Plastic Packaging Waste—A Comparison between Austria, Germany and The Netherlands

Setting up strategies for a sound management of plastic packaging waste (PPW) is becoming increasingly crucial at many levels of the value chain in Europe. After the very first implementation of an extended producer responsibility scheme in Germany in 1991, many EU Countries followed. This resulted in a complex network of schemes that differ from one member state to another. This paper brings together the three latest studies describing the current flows of PPW across the waste value chain from Austria (reference year 2013), Germany and the Netherlands (reference year 2017). With this aim, the models of the three single studies have been adapted to fit into a common model, allowing to perform a comparative analysis. Although with a relatively comparable product market, the three countries have different management systems (e.g., separate collection systems, target sorting products and treatment of residual waste), reflecting different national strategies to achieve the circular economy targets. Recycling rates (in terms of washed milled goods at the output of the recycling process) for the three countries resulted in 23%, 43% and 30% of the total mass of PPW generated in, respectively, Austria, Germany and the Netherlands. The fraction of mixed recycled plastics, relevant for Germany and the Netherlands only, was determined to be one of the major determinants of the differences in recycling rates. Furthermore, the discussion revolves around new political targets that have the potential to contribute to addressing the issue of tradeoff between quantity and quality of recycled plastics placed on the market, with measures such as design-for-recycling and eco-modulation of EPR fees playing a critical role, while also pointing out the aspects that inevitably hinder closed-loop recycling.

Validation of the Application of the Pyrolysis Process for the Treatment and Transformation of Municipal Plastic Wastes

Only around 30 % of the 27.1 million tonnes of plastic waste recovered annually in Europe is being recycled efficiently into new products. The most common way to recycle plastics nowadays is through mechanical recycling methods that involve sorting plastics by type, melting them and reprocessing into recycled products. Mechanical recycling requires clean, high-purity mono-material streams, that must be obtained by separation at source (by the citizen or industry) or by manual or automated sorting of mixed waste streams. However, this degree of separation is very difficult or even impossible due to composition or contamination of the plastic waste, such is the case for example of complex materials like composites, made of more than one material that in most cases cannot be separated, and of highly contaminated plastic residues (e.g. food packaging). In economic terms, plastic recycling is not always cost-efficient since many times recycling costs are not covered by the prices of the recycled plastics. As a result, approximately 70 % of European plastic waste is not recycled due to technical or economic reasons, so, they are sent to landfill or to incineration. One of the possible solutions to deal with this type of plastic wastes is the pyrolysis process which allows taking profit of plastics organic matter and tolerates a certain degree of contamination. Pyrolysis products have good quality. Gases have high calorific value and liquids have high energetic content and stability characteristics, including well-defined distillation point, stability of physical properties, low acidity, and high miscibility with conventional fuels. However, products obtained by plastic waste pyrolysis depend on the operational conditions and are strongly affected by the type of plastic waste used. The main purpose of this study is to validate the application of the pyrolysis process for treatment and transformation of plastic mix (essentially derived from MSW and from end-of-life composites) into mainly profitable liquids, together with gases and solid by using thermal (or catalytic) pyrolysis. The raw materials studied were waste streams from municipal solid waste (MSW), containing mainly plastic (i.e. PE, PP, PS, and small amounts of PET and PVC) separated from organic waste pool, as well as end-of-life composites (i.e. packages, electrical wastes, vehicles, etc.). After sorting of these waste materials, plastic fractions of different composition were processed in the pyrolysis reactor. The pyrolysis experiments were carried out in batch 5.5 L reactor using different mixtures, operational conditions and catalysts. All gaseous hydrocarbons produced were measured and collected for direct analysis by gas chromatography (GC), whilst liquid hydrocarbons were distilled and solids were extracted with hexane. Liquid fractions were analysed using a GC-MS (gas chromatography-mass spectrometry) to identify their main compounds, which were quantified by GC. The experimental results obtained showed that, for instance, the use of polystyrene favoured highly the formation of aromatic compounds, mainly toluene, ethylbenzene and xylene, while in presence of polyethylene the hydrocarbons produced are mainly paraffins. Also, the presence of PS, PET and PVC increases the solid content, decreasing the liquid yield.

Efficient extraction of metals from thermally treated waste printed circuit boards using solid state chlorination: Statistical modeling and optimization

Formal recycling of e-waste is necessary for recovery of valuable metals and to avoid environmental damage due to use of toxic chemicals and illegal disposal of the leftovers. This study focused on development of an effective and environment-friendly method to extract valuable metals from waste printed circuit boards (WPCBs) using low temperature solid state chlorination followed by water leaching method. The shredded WPCBs were thermally pre-treated at 600 °C to convert plastic fraction into oil and combustible gases. The acquired metal rich residue (T-WPCBs) was chlorinated subsequently with NH4Cl. A combination of central composite design-response surface methodology (CCD-RSM) was successfully implemented into modeling the chlorination process for extraction of Au and Cu as a function of the process variables viz. temperature, time and NH4Cl dose. More than 96% of Cu and 67% of Au were extracted with water, when the T-WPCBs powder was chlorinated with 3 g/g of NH4Cl at 300 °C for 3 h. However, the proposed process has potential to extract other metals also; hence, the added credibility of the process was revealed by reporting extraction of other valuable metals such as Ni, Fe, Pb, Ag, and Zn at optimized conditions. This study strives to develop a closed loop process for extraction of metals; therefore, NH4Cl, the lone chemical used herein, was recycled for an economically viable process. Unlike the traditional pyrometallurgical process, which operates above 1000 °C and produces toxic fumes and soot, this process works at a low temperature range of 275–325 °C and able to extract out more than 90% of the total metal content without generating any toxic fume and soot.

Influence of Loading History and Soil Type on the Normal Contact Behavior of Natural Sand Grain-Elastomer Composite Interfaces.

Recycled rubber in granulated form is a promising geosynthetic material to be used in geotechnical/geo-environmental engineering and infrastructure projects, and it is typically mixed with natural soils/aggregates. However, the complex interactions of grains between geological materials (considered as rigid bodies) and granulated rubber (considered as soft bodies) have not been investigated systematically. These interactions are expected to have a significant influence on the bulk strength, deformation characteristics, and stiffness of binary materials. In the present study, micromechanical-based experiments are performed applying cyclic loading tests investigating the normal contact behavior of rigid–soft interfaces. Three different geological materials were used as “rigid” grains, which have different origins and surface textures. Granulated rubber was used as a “soft” grain simulant; this material has viscoelastic behavior and consists of waste automobile tires. Ten cycles of loading–unloading were applied without and with preloading (i.e., applying a greater normal load in the first cycle compared with the consecutive cycles). The data analysis showed that the composite sand–rubber interfaces had significantly reduced plastic displacements, and their behavior was more homogenized compared with that of the pure sand grain contacts. For pure sand grain contacts, their behavior was heavily dependent on the surface roughness and the presence of natural coating, leading, especially for weathered grains, to very high plastic energy fractions and significant plastic displacements. The behavior of the rigid–soft interfaces was dominated by the rubber grain, and the results showed significant differences in terms of elastic and plastic fractions of displacement and dissipated energy compared with those of rigid interfaces. Additional analysis was performed quantifying the normal contact stiffness, and the Hertz model was implemented in some of the rigid and rigid–soft interfaces.