Post-consumer Plastic Waste Research Articles

China restricts imports of plastic trash

A Chinese government policy aimed at curbing imports of postconsumer plastic waste went into effect Jan. 1, leaving recyclers in the U.S. and elsewhere without a market for much of their plastic waste and causing material to pile up. U.S. localities, particularly on the West Coast, have for many years shipped plastics collected in recycling programs to China. Low wages make China an ideal place for the labor-intensive sorting of plastic waste. According to the U.S. Census Bureau and the U.S. International Trade Commission, China imported 776,000 metric tons of reclaimed plastic and 13 million metric tons of recycled paper from the U.S. in 2016. The total value was $2.3 billion. China officially notified the World Trade Organization last summer that it would restrict the import of 24 types of waste. It explained that dirty and hazardous substances mixed with plastic and other waste pose a risk to health and

Spatial Variation of Plastic Waste Generation in Present Sri Lanka

An understanding of the spatial variations of solid waste generation helps in many ways to design waste management policies particularly at micro-regional levels. Many of the studies have focused different factors behind the postconsumer plastic waste generation as the determinants, but few of them focused on the spatial variation in finding durable solutions. In this study, quantitative and qualitative techniques were used to identify the spatial variation of plastic waste generation in Sri Lanka. Research results reveals that the per capita generation of plastic waste has a significant variation among provinces, districts and LGAs. The per capita plastic waste at national level is 0.11 kg per week and 5.72 kg per year. This finding coincides approximately with the Sri Lanka custom data of annual plastic import for consumption (5kg per head in 2014). The most prominently used plastic items are lunch sheets, polythene bags, shopping bags and wrappers of food items. It is revealed that the spatial variation of plastic waste generation is very dynamic among the districts and LGAs. Despite the western province, the second highest generation of plastic waste is recorded in the Eastern province. The study concludes that those significant findings could provide quick, useful and low-cost decision support to find durable solutions for emerging issues of post consumer plastic waste generation.

Strength and permeability of pervious composite prepared by using post-consumer plastic waste bottles

This study focused on developing and evaluating a novel form of pervious polyethylene terephthalate (PET) plastic composite. This novel composite, called as PPC, produced from plastic waste, soil and aggregates, will offer an effective technique for reducing storm water runoff and help divert a large amount of plastic from landfills and incinerators. PPC samples with different PET to soil/aggregate ratios were prepared and then tested for indirect tensile strength and permeability. Permeability was conducted in a unique manner by designing and fabricating a new testing equipment. Both indirect tensile strength and permeability were within the expected values found in the literature for porous pavements. Results showed that indirect tensile strength values increased with PET content. It was also found that using PET alone is not strong enough in binding aggregates and therefore, a soil/PET ratio of one was found optimum for providing maximum strength. Permeability values decreased with the decrease of A/P (aggregate/PET) ratio which in general indicates that lower PET and higher aggregate content is suitable for higher permeability. A soil/PET ratio of one was found to provide higher permeability but strength could compromise. Findings from this study indicated that developed PPC could be used for low-strength construction such as driveways, sidewalks and parking lots.

Impact strength, permeability and chemical resistance of concrete reinforced with metalized plastic waste fibers

This paper represents the results of experimental investigations of impact strength and durability properties of concrete reinforced with post-consumer metalized plastic waste (MPW) generated from the discarded food packaging plastics. The addition of MPW into the conventional concrete can extend a dual benefit of reduced hazards on the environment and improved mechanical and durability properties of concrete. The MPW films were shredded into the macro fibers of varying lengths of 5 mm, 10 mm, and 20 mm and mixed into the concrete by volume fractions from 0% to 2%. The test results showed excellent improvement of the impact resistance by concrete containing MPW fibers of 20 mm length compared to the conventional concrete. The resistance against acid and sulfate attack, chloride penetration, corrosion of concrete, water, and air permeability, and the resistance to the water sorptivity were improved due to the addition of 5 mm length short MPW fibers. For all test conditions, the maximum improvement was observed with the addition of 1% volume fraction of MPW fibers mixed into the conventional concrete.

Transportation fuel from plastic: Two cases of study

Synthesis of liquid fuels from waste is a promising pathway for reducing the carbon footprint of transportation industry and optimizing waste management towards zero landfilling.The study of commercial plants that conduct pyrolysis of plastics from post-consumer recycled materials and directly mine from old landfills without any pre-treatment has revealed two cases that show the feasibility of manufacturing transportation fuels via these methods.Pyrolysis oil, consisting of almost 26% hydrocarbons within the gasoline range and almost 70% within the diesel range, is upgraded to transportation fuel in the existing refinery. A batch operating plant is able to deliver relatively good quality pyrolysis oil from post-consumer plastic waste, owing to the catalyst employed. Simple distillation was also evaluated as an alternative and cheaper upgrading process into transportation fuels, meeting EN590 diesel and ISO8217 marine fuel standards.Even though the two installations are outside the European Union, they represent good examples of the “circular economy” concept envisaged by the European Union via its ambitious “Circular Economy Package [1]”, providing real world data for comparison with other experimental and lab results.1In a circular economy waste and resource use are minimized, and when a product reaches the end of its life, it is used again to create further value.

Development of a new approach based on midwave infrared spectroscopy for post-consumer black plastic waste sorting in the recycling industry

Waste sorting is key to the process of waste recycling. Exact identification of plastic resin and wood products using Near Infrared (NIR, 1–1.7µm) sensing is currently in use. Yet, dark targets characterized by low reflectance, such as black plastics, are hard to identify by this method. Following the recent success of Midwave Infrared (MWIR, 3–12µm) measurements to identify coloured plastic polymers, the aim of this study was to assess whether this technique is applicable to sorting black plastic polymers and wood products. We performed infrared reflectance contact measurements of 234 plastic samples and 29 samples of wood and paper products. Plastic samples included black, coloured and transparent Polyethylene Terephthalate (PET), Polyethylene (PE), Polyvinyl Chloride (PVC), Polypropylene (PP), Polylactic acid (PLA) and Polystyrene (PS). The spectral signatures of the black and coloured plastic samples were compared with clear plastic samples and signatures documented in the literature to identify the polymer spectral features in the presence of coloured material. This information was used to determine the spectral bands that best suit the sorting of black plastic polymers. The main NIR-MWIR absorption features of wood, cardboard and paper were identified as well according to the spectral measurements. Good agreement was found between our measurements and the absorption features documented in the literature. The new approach using MWIR spectral features appears to be useful for black plastics as it overcomes some of the limitations in the NIR region to identify them. The main limitation of this technique for industrial applications is the trade-off between the signal-to-noise ratio of the sensor operating in standoff mode and the speed at which waste is moved under the sensor. This limitation can be resolved by reducing the system’s spectral resolution to 16cm−1, which allows for faster spectra acquisition while maintaining a reasonable signal-to-noise ratio.

Green synthesis of graphene from recycled PET bottle wastes for use in the adsorption of dyes in aqueous solution

Polyethyleneterephthalate (PET) is an important component of post-consumer plastic waste. This study focuses on the potential of utilizing "waste-treats-waste" by synthesis of graphene using PET bottle waste as a source material. The synthesized graphene is characterized by SEM, TEM, BET, Raman, TGA, and FT-IR. The adsorption of methylene blue (MB) and acid blue 25 (AB25) by graphene is studied and parameters such as contact time, adsorbent dosage were optimized. The Response Surface Methodology (RSM) is applied to investigate the effect of three variables (dye concentration, time and temperature) and their interaction on the removal efficiency. Adsorption kinetics and isotherm are followed a pseudo-second-order model and Langmuir and Freundlich isotherm models, respectively. Thermodynamic parameters demonstrated that adsorption of dye is spontaneous and endothermic in nature. The plastic waste can be used after transformation into valuable carbon-based nanomaterials for use in the adsorption of organic contaminants from aqueous solution.

Drivers to Sustainable Plastic Solid Waste Recycling: A Review

Waste recycling is a livelihood for the marginalized society in the developing economies and it is not surprising to find recycling of municipal solid waste (MSW) been carried out. Plastic waste is a waste type in MSW yet a number of challenges still exist in managing this waste type. A literature review was conducted to identify the key drivers to sustainable development of post-consumer packaging plastic waste recycling systems in developed and developing economies. A number of articles focusing on drivers or factors influencing sustainable management and recycling of solid waste and municipal solid waste were reviewed. Further analysis of the results indicated a number of drivers from the economic, environmental and social aspect as drivers to sustainable development of recycling systems for post-consumer packaging plastic solid waste.

Gravity packaging final waste recovery based on gravity separation and chemical imaging control

Plastic polymers are characterized by a high calorific value. Post-consumer plastic waste can be thus considered, in many cases, as a typical secondary solid fuels according to the European Commission directive on End of Waste (EoW). In Europe the practice of incineration is considered one of the solutions for waste disposal waste, for energy recovery and, as a consequence, for the reduction of waste sent to landfill. A full characterization of these products represents the first step to profitably and correctly utilize them. Several techniques have been investigated in this paper in order to separate and characterize post-consumer plastic packaging waste fulfilling the previous goals, that is: gravity separation (i.e. Reflux Classifier), FT-IR spectroscopy, NIR HyperSpectralImaging (HSI) based techniques and calorimetric test. The study demonstrated as the proposed separation technique and the HyperSpectral NIR Imaging approach allow to separate and recognize the different polymers (i.e. PolyVinyl Chloride (PVC), PolyStyrene (PS), PolyEthylene (PE), PoliEtilene Tereftalato (PET), PolyPropylene (PP)) in order to maximize the removal of the PVC fraction from plastic waste and to perform the full quality control of the resulting products, can be profitably utilized to set up analytical/control strategies finalized to obtain a low content of PVC in the final Solid Recovered Fuel (SRF), thus enhancing SRF quality, increasing its value and reducing the “final waste".

Solid-state drawing of post-consumer isotactic poly(propylene): Effect of melt filtration and carbon black on structural and mechanical properties

Post-consumer plastic waste obtained via mechanical recycling is usually applied in thick-walled products, because of the low mechanical strength due to the presence of contaminants. In fact, sorted post-consumer isotactic poly(propylene) (i-PP) can be considered as a blend of 95% i-PP and 5% poly(ethylene), with traces of poly(ethylene terephthalate) (PET). By applying a treatment such as solid-state drawing (SSD) after melt extrusion, the polymer chains can be oriented in one direction, thereby improving the stiffness and tensile strength. In this research, molecular processes such as crystal break-up and chain orientation of these complex blends were monitored as a function of draw ratio. The melt filter mesh size – used to exclude rigid PET particles – and the addition of carbon black (CB) – often added for coloration in the recycling industry – were varied to investigate their influence on the SSD process. This research shows that despite the blend complexity, the molecular processes during SSD compare to virgin i-PP and that similar draw ratios can be obtained (λmax=20), albeit at reduced stiffness and strength as a result of the foreign polymers present in post-consumer i-PP. It is observed that the process stability improves with decreasing mesh size and that higher draw ratios can be obtained. The addition of carbon black, which resides in the dispersed PE phase, also stabilizes the SSD process. Compared to isotropic post-consumer i-PP, the stiffness can be improved by a factor 10 to over 11GPa, while the tensile strength can be improved by a factor 15–385MPa, which is approx. 70% of the maximum tensile strength achieved for virgin i-PP.

Experimental and theoretical studies on the properties of injection moulded glass fibre reinforced mixed plastics composites

Recycled mixed post-consumer and post-industrial plastic wastes consisting of HDPE, LDPE and PP were injection moulded with short glass fibre (10–30% by weight) to produce a new generation composite materials. Intensive experimental studies were then performed to characterise the tensile, compression and flexural properties of glass fibre reinforced mixed plastics composites. With the addition of 30wt.% of glass fibre, the strength properties and elastic modulus increased by as much as 141% and 357%, respectively. The best improvement is seen in the flexural properties due to the better orientation of the glass fibres in the longitudinal direction at the outer layers. The randomness and length of the glass fibre were accounted to modify the existing rule of mixture and fibre model analysis to reliably predict the elastic and strength properties of glass fibre reinforced mixed plastics composites.

STRENGTH CHARACTERISTICS OF CONCRETE CONTAINING POST CONSUMER METALIZED PLASTIC WASTE

This paper represents results of strength tests conducted on concrete containing flakes of waste metalized plastics. The feasibility of post consumer plastic waste (PCMPW) was determined on the bases of tests results of compressive strength and split tensile strength. Ever increasing generation of PCMPW has raised littering issues and has become one of the major sources for landfills. The objective of the test program was to check the feasibility of PCMPW as concrete constituent and possible way of mitigating the environmental impacts occurring from insufficient and unsafe management of PCMPW. The strength tests were performed with three sizes of PCMPW in flaks and fiber form. PCMPW was added in the mixes with 0%, 0.5%, 1%, 1.5% and 2% by volume of concrete mix. Test results reveled that strengths reduced with increased PCMPW flakes contents. However, up to 1% of addition of flakes the strength reduction was negligible for all flak sizes. Moreover, the PCMPW fiber with 1mmx17mm size improved the split tensile strength. Experimental results of compressive –split tensile strength were correlated by a standard analytical model and exhibited good agreement with the experimental results. Such concrete could be utilized in pavements, substructural components and in non-structural members.

Contribution of plastic waste recovery to greenhouse gas (GHG) savings in Spain

This paper concentrates on the quantification of greenhouse gas (GHG) emissions of post-consumer plastic waste recovery (material or energy) by considering the influence of the plastic waste quality (high or low), the recycled plastic applications (virgin plastic substitution or non-plastic substitution) and the markets of recovered plastic (regional or global). The aim is to quantify the environmental consequences of different alternatives in order to evaluate opportunities and limitations to select the best and most feasible plastic waste recovery option to decrease the GHG emissions. The methodologies of material flow analysis (MFA) for a time period of thirteen years and consequential life cycle assessment (CLCA) have been integrated. The study focuses on Spain as a representative country for Europe. The results show that to improve resource efficiency and avoid more GHG emissions, the options for plastic waste management are dependent on the quality of the recovered plastic. The results also show that there is an increasing trend of exporting plastic waste for recycling, mainly to China, that reduces the GHG benefits from recycling, suggesting that a new focus should be introduced to take into account the split between local recycling and exporting.

Thermal and spectroscopic (TG/DSC–FTIR) characterization of mixed plastics for materials and energy recovery under pyrolytic conditions

Seven waste thermoplastic polymers (polypropylene, polyethylene film, polyethylene terephthalate, polystyrene, acrylonitrile–butadiene–styrene, high-impact polystyrene and polybutadiene terephthalate, denoted as PP, PE (film), PET, PS, ABS, HIPS and PBT, respectively) and four synthetic mixtures thereof with different compositions representing commingled postconsumer plastic waste and waste of electrical and electronic equipment were studied by means of simultaneous thermogravimetry/differential scanning calorimetry coupled with Fourier transform infrared spectroscopy (TG/DSC–FTIR) under pyrolytic conditions (inert atmosphere). By summing all the heat change contributions due to physical and/or chemical processes occurring (i.e., melting, decomposition), an overall energy, defined as the degradation heat, was determined for both single component and their mixtures. It was found to be about 4–5 % of the exploitable energy of the input material. Vapors evolved during the pyrolysis of single-component polymers and their mixtures, analyzed using the FTIR apparatus, allowed identifying the main reaction products as monomers or fragments of the polymeric chain. Results from TG/DSC runs and FTIR analysis show that there is no interaction among the plastic components of the mixtures during the occurrence of pyrolysis.

Chemical depolymerisation of PET complex waste: hydrolysis vs. glycolysis

The huge increase in the generation of post-consumer plastic waste has produced a growing interest in eco-efficient strategies and technologies for their appropriate management and recycling. In response to this, PROQUIPOL Project is focused on developing, optimizing and adapting feedstock recycling technologies as an alternative for management for the treatment of complex plastic waste. Among the different plastic wastes studied, PROQUIPOL Project is working on providing a suitable treatment to the highly colored and complex multilayered post-consumer waste fractions of polyethylene terephthalate (PET) by chemical depolymerisation methods. Glycolysis and alkali hydrolysis processes have been studied with the aim of promoting the transformation of PET into the bis(2-hydroxyethyl) terephthalate monomer and terephthalic acid, respectively. In both cases operational conditions such as temperature, reaction time, catalyst to PET rate and solvent to PET rate have been considered to optimize product yield, achieving values near to 90 % and monomer purities over 95 % in both processes. This paper presents results obtained for each treatment as well as a simplified comparison of technical, economic and environmental issues.

Distributed Recycling of Post-Consumer Plastic Waste in Rural Areas

ABSTRACTAlthough the environmental benefits of recycling plastics are well established and most geographic locations within the U.S. offer some plastic recycling, recycling rates are often low. Low recycling rates are often observed in conventional centralized recycling plants due to the challenge of collection and transportation for high-volume low-weight polymers. The recycling rates decline further when low population density, rural and relatively isolated communities are investigated because of the distance to recycling centers makes recycling difficult and both economically and energetically inefficient. The recent development of a class of open source hardware tools (e.g. RecycleBots) able to convert post-consumer plastic waste to polymer filament for 3-D printing offer a means to increase recycling rates by enabling distributed recycling. In addition, to reducing the amount of plastic disposed of in landfills, distributed recycling may also provide low-income families a means to supplement their income with domestic production of small plastic goods. This study investigates the environmental impacts of polymer recycling. A life-cycle analysis (LCA) for centralized plastic recycling is compared to the implementation of distributed recycling in rural areas. Environmental impact of both recycling scenarios is quantified in terms of energy use per unit mass of recycled plastic. A sensitivity analysis is used to determine the environmental impacts of both systems as a function of distance to recycling centers. The results of this LCA study indicate that distributed recycling of HDPE for rural regions is energetically favorable to either using virgin resin or conventional recycling processes. This study indicates that the technical progress in solar photovoltaic devices, open-source 3-D printing and polymer filament extrusion have made distributed polymer recycling and upcycling technically viable.

Preparation and evaluation of activated carbons obtained by physical activation of polyethyleneterephthalate (PET) wastes

Polyethyleneterephthalate (PET), has become one of the major post-consumer plastic wastes. In this work, PET wastes were used to produce activated carbon by physical activation method, using carbon dioxide (CO2) for gasification. The effects of the production variables such as temperature, heating rate, flow rate and holding time of carbonization stage and activation stage on the adsorption capacity of activated carbon were investigated. Preparation tests for the effects of these factors were designed with Taguchi method. According to the Taguchi parameter design methodology, L16 orthogonal array was used. Analysis of experimental results showed that, the most effective factors on each experimental design response were activation temperature and holding time in both stage. The optimum conditions for activated carbons production from PET wastes were found to be as follows: carbonization temperature 800°C, carbonization time 60min, activation temperature 975°C, activation time 240min, heating rate of carbonization and activation 10k/min, flow rate N2 200ml/min and CO2 100ml/min. The properties of prepared activated carbon at optimum operating conditions such as surface area 790m2/g and iodine number 630mg I2/g C, were comparable to commercial activated carbons.

Potential of best practice technology to improve energy efficiency in the global chemical and petrochemical sector

The chemical and petrochemical sector is by far the largest industrial energy user, accounting for 30% of the industry’s total final energy use. However, due to its complexity its energy efficiency potential is not well understood. This article analyses the energy efficiency potential on a country level if Best Practice Technologies (BPT) were implemented in chemical processes. Two approaches are applied and an improved dataset referring to Europe has been developed for BPT energy use. This methodology has been applied to 66 products in fifteen countries that represent 70% of chemical and petrochemical sector’s energy use worldwide. The results suggest a global energy efficiency potential of 16% for this sector, excluding savings in electricity use and by higher levels of process integration, combined heat and power (CHP) and post-consumer plastic waste treatment. The results are more accurate than previous estimates. The results suggest significant differences between countries, but a cross-check based on two different methods shows that important methodological and data issues remain to be resolved. Further refinement is needed for target setting, monitoring and informing energy and climate negotiation processes. For the short and medium term, a combination of benchmarking and country level analysis is recommended.

Characterization of Clayey Soils from Congo and Physical Properties of Their Compressed Earth Blocks Reinforced with Post-Consumer Plastic Wastes

Physical properties of compressed earth blocks reinforced with plastic wastes are compared to those of nonreinforced ones. These bricks are made with two clayey soils from two deposits of Congo located in Brazzaville and Yengola. Mineralogical and geotechnical analysis revealed that the soil of Brazzaville is mainly composed of kaolinite whereas that of Yengola is a mixture of kaolinite and illite. The amounts of clay (46 and 48%, respectively) are higher than those usually recommended for bricks’ production without stabilizers. Despite this difference of mineralogical compositions, the physical properties of these soils are quite similar. The compressive strength of the resulted bricks compacted with an energy of 2.8 MPa is about 1.5 MPa, which is the lower limit value allowed for adobes. Reinforcing with polyethylene waste nets increased the strength by about 20 to 30% and slightly enhanced resistance to water, Young’s modulus and strain to failure. However, the reinforcement had no significant effect either on bricks’ curing length or on their shrinkage.

Plastic waste management in the context of a European recycling society: Comparing results and uncertainties in a life cycle perspective

A number of life cycle assessment (LCA) studies have been undertaken within the last 15 years comparing end-of-life treatment options for post-consumer plastic waste, including techniques such as: mechanical recycling, feedstock recycling, incineration with energy recovery and landfilling. These have attempted to support decisions in the formulation of waste management strategies and policies. In light of the introduction of life cycle thinking into European waste policies, specifically in relation to the waste hierarchy, a literature review of publically available LCA studies evaluating alternative end-of-life treatment options for plastic waste has been conducted. This has been done in order to: establish if a consensus exists as to the environmentally preferable treatment option for plastic waste; identify the methodological considerations and assumptions that have led to these conclusions; and determine the legitimacy of applying the waste hierarchy to the plastic waste stream. The majority of the LCA studies concluded that, when single polymer plastic waste fractions with little organic contamination are recycled and replace virgin plastic at a ratio of close to 1:1, recycling is generally the environmentally preferred treatment option when compared to municipal solid waste incineration. It has been found that assumptions relating to the virgin material substitution ratio and level of organic contamination can have a significant influence upon the results of these studies. Although a limited number of studies addressed feedstock recycling, feedstock recycling and the use of plastic waste as a solid recovered fuel in cement kilns were preferred to municipal solid waste incineration. Landfilling of plastic waste compared to municipal solid waste incineration proved to be the least preferred option for all impact categories except for global warming potential. Due to the uncertainty surrounding some assumptions in the studies, it cannot be said with confidence that the waste hierarchy should be applied to plastic waste management as a general rule.