Search Results (46)

The increasing accumulation of plastic waste—especially from packaging and post-consumer sources—calls for the development of sustainable recycling strategies. Due to the challenges associated with sorting mixed waste, directly processing waste streams offers a practical approach. Polyethylene terephthalate (PET) and high-density polyethylene (HDPE) are common consumer plastics, but they are difficult to recycle together due to immiscibility and degradation. In mixed waste, recycled HDPE (r-HDPE) often contaminates the recycled PET (r-PET) stream. Additive manufacturing (AM) offers a promising solution to upcycle these mixed polymers into functional products with minimal waste. This study investigates the processing and characterization of r-PET/r-HDPE blends for AM, focusing on the role of compatibilizers in enhancing their properties. Blends were melt-compounded using a twin-screw extruder to improve dispersion, followed by direct pellet-based 3D printing. A compatibilizer (0–7 php) was incorporated to improve miscibility. Rheological testing showed that the 5 php compatibilizer optimized viscosity and elasticity, ensuring smoother extrusion. Thermal analysis revealed a 30 °C increase in crystallization temperature and a shift in decomposition temperature from 370 °C to 400 °C, indicating improved thermal stability. Mechanical testing showed a tensile strength of 35 MPa and 17% elongation at break at optimal loading. Scanning electron microscopy (SEM) confirmed reduced phase separation and improved morphology. This work demonstrates that properly compatibilized r-PET/r-HDPE blends enable sustainable 3D printing without requiring polymer separation. The results highlight a viable path for the conversion of plastic waste into high-value, customizable components, contributing to landfill reduction and advancing circular economy practices in polymer manufacturing. Full article

Achieving the mainstream adoption of circular packaging is essential for mitigating the environmental impacts of plastic waste. Its widespread adoption, however, remains hindered by significant user barriers. This study investigates the barriers to user adoption of upstream packaging solutions in Indonesia with the aim of reducing plastic packaging waste. Through a mixed-methods approach including case studies, expert workshops, and focus group discussions, nine key barriers were identified and analysed. These include inconvenience, resistance to changing habits and behaviours, higher costs and deposit schemes, contamination and hygiene concerns, wear and tear, functional and performance limitations, a lack of awareness about the environmental impacts, limited availability and variety, and a lack of trust. This research advances the literature by offering a detailed analysis of these barriers, categorising them into sociocultural, economic, contextual, and regulatory aspects. Additionally, barriers specific to Indonesia were identified such as a shift from being served to self-service refilling, some people not having smartphones, poor cellular signals in rural areas, a preference for plastic packaging due to its resale value, and a preference for cash payments due to limited access to credit or bank cards. The findings highlight the need for tailored, multidisciplinary strategies to overcome these barriers and promote the adoption of circular packaging solutions. This research provides valuable insights for researchers studying circular design, businesses seeking to innovate upstream packaging solutions, and policymakers aiming to develop regulations that support the adoption of circular packaging practices. Full article

Incineration remains Europe’s main practice for plastic packaging waste treatment, primarily due to the limitations of mechanical recycling technology. Consequently, research and development of more sustainable and flexible approaches are of high importance. Thermochemical conversion of polypropylene, polystyrene, and municipal plastic packaging mix via high-temperature flash pyrolysis (1000 °C/s) is studied in this research, focusing on the kinetics and yields of the devolatilisation stage. The primary stage results in the formation of volatile organic compounds considered intermediate products for carbon black production. The experiments were conducted in a pressurised wire mesh reactor, investigating the influence of temperature (600–1200 °C), residence time (0.5–10 s), and pressure (1–25 bar). The positive effect of temperature on the volatile yield was observed up to 2–5 s. The devolatilisation stage was completed within a maximum of 5 s at temperatures ranging from 800 to 1200 °C. The pressure was determined to be a kinetically limiting factor of the process to up to 800 °C, and the effect was not present at ≥1000 °C. Raman spectroscopy measurements revealed that pyrolytic carbon deposited on the post-experimental meshes is structurally similar to the industrially produced carbon black. The kinetic data and developed model can be further applied in the upscale reactor design. Full article

The composition of plastic and multilayer packaging waste was assessed in the mixed municipal solid waste (MSW) streams of the Kaunas (Lithuania), Daugavpils (Latvia) and Tallinn (Estonia) municipalities. For the analysis of samples in the mixed MSW streams, the authors used manual sorting and a visual recognition method. Composition analysis of plastic and multilayer packaging waste from separately collected waste of multi-family and single-family households was performed in the Kaunas and Tallinn municipalities. For the analysis of samples in the separately collected waste streams, the research group combined manual sorting and near-infrared (NIR) spectroscopy methods. The findings reveal that the percentage distribution of plastic and multilayer packaging waste within the municipal solid waste (MSW) stream is relatively consistent across the municipalities of Kaunas, Daugavpils and Tallinn, comprising 40.16%, 36.83% and 35.09%, respectively. However, a notable variation emerges when examining separately collected plastic and multilayer packaging waste streams. In this category, the proportion of plastic and multilayer packaging within the total separately collected packaging waste stream ranges from 62.05% to 74.7% for multi-family residential buildings and from 44.66% to 56.89% for single-family residential buildings. The authors provided further insights for the enhanced recycling potential of different plastic materials through improved sorting. Full article

Asphalt mixtures can include various recycled materials, which often replace some of the coarse and fine aggregate components. In some cases, a percentage of material called mineral filler, made up of particles that pass through a No. 200-sieve, is also admitted in the preparation of the mixture. With the increasing amount of packaging used as containers for various products, many of which need to be disposed of properly and become an environmental burden in warehouses without proper reuse, there is potential for including these elements in the sustainable modification of asphalt mixtures. This research suggests reusing plastic and aluminum coffee capsules, which are difficult to recycle. While most studies crush recycled materials to sizes smaller than 0.075 mm for use in mixes, this research focuses on assembling the waste capsules into a network of cells inside specimens subjected to bending to observe the mechanical behavior of the asphalt mixture. The findings indicate that incorporating capsule networks can lead to a significant enhancement in the flexural strength of the examined beams, with an increase of up to 200%. Moreover, the deformation is reduced by an average of 66% upon the emergence of the initial crack in the specimen. Full article

Mixed plastic packaging waste sorting residue (MPO323) was treated by thermal pyrolysis to utilize pyrolysis oil and char. The pyrolysis oil was found to contain aromatic and aliphatic hydrocarbons. The chlorine and bromine contents were as high as 40,000 mg/kg and 200 mg/kg, respectively. Additionally, other elements like sulfur, phosphorous, iron, aluminum, and lead were detected, which can be interpreted as impurities relating to the utilization of oils for chemical recycling. The pyrolysis char showed high contents of potentially active species like silicon, calcium, aluminum, iron, and others. To enhance the content of aromatic hydrocarbons and to reduce the level of contaminants, pyrolysis oil was reformed with the corresponding pyrolysis char to act as an active material in a fixed bed. The temperature of the reactor and the flow rate of the pyrolysis oil feed were varied to gain insights on the cracking and reforming reactions, as well as on performance with regard to decontamination. Full article

Plastic packaging waste (PPW) can be considered as solid waste with harmful effects on the environment or as a material with recycling potential in terms of sustainable development in a circular economy. Knowing the amount of PPW generated is very important as it is related to the availability of this material for recycling and determines the actual recycling rate (denominator of a fraction). PPW is very heterogeneous and contains a certain number of impurities (e.g., product residues, direct printing, glue, labels, plastic sleeves, cap, etc.). According to EU law, an annual report (for the data in 2021) on the masses of both the PPW actually recycled (PPW_R) (“targeted materials”) and impurities (“non-targeted materials”) must be prepared and submitted to the European Commission. The PPW_R is used for the calculation of the recycling rate (the numerator in a fraction). The impurities should be considered for the calculation of own resources (national contributions to the general EU budget based on the uniform call rate of 0.80/kg of non-recycled PPW). To date, the Council of the EU has not proposed a method for calculating these amounts, so they have only been estimated. The present study (the first of its kind in Poland) aimed to estimate the number of impurities in PPW and the actual amount of PPW_R at the calculation point using a method accepted by the EU. In the installations, PPW (plastic packaging (15 01 02), multi-material packaging (15 01 05) and mixed packaging waste (15 01 06)) is recycled together with other plastic waste (plastic (16 01 19), plastic (17 02 03), plastic and rubber (19 12 04), and plastics (20 01 39)). It was assumed that the proportions of the mass of individual types of PPW in the total mass of plastic waste processed in the installation were proportional to the mass of impurities in these individual types of PPW. It was found that the average percentage of impurities in PPW was 4.40–6.90%, which seems to be relatively low. However, this means that, when calculating the PPW_R, the mass of impurities should be subtracted from the mass of PPW entering the recycling process. As a result, the mass of PPW_R at the calculation point in 2021 in Poland was almost 30,000 tonnes lower than the original mass entering the installation. Thus, applying the uniform call rate to the weight of impurities in the PPW increases Poland’s own resources by approx. 24 million euros. Full article

This paper describes the process used to produce thermoplastic building materials from non-recyclable mixed plastic–paper packaging waste. A first step was dedicated to an innovative and sustainable sterilization technology for non-recyclable waste, based on exposure to microwave radiation in closed air-circulation ovens. Further, composites with different cellulose contents and with two polymer matrices, respectively, were obtained using an injection process, and the samples were subjected to mechanical and physical tests. Due to their superior features, the products based on mixed polypropylene–paper packaging waste may successfully replace the classic polyvinylchloride-based wood–plastic composites. The environmental impact of mixed plastic–paper packaging waste was analyzed, and the sustainability of the thermoplastic technology was demonstrated from an economic and environmental point of view. Full article

Polymers generally form incompatible mixtures that make the process of recycling difficult, especially the mechanical recycling of mixed plastic waste. One of the most commonly used films in the packaging industry is multilayer films, mainly composed of polyethylene (PE) and polyamide (PA). Recycling these materials with such different molecular structures requires the use of compatibilizers to minimize phase separation and obtain more useful recycled materials. In this work, commercial polyisoprene–graft–maleic anhydride (PI-g-MA) was tested as a compatibilizer for a blend of PE and PA derived from the mechanical recycling of PE/PA multilayer films. Different amounts of PI-g-MA were tested, and the films made with 1.5% PI-g-MA showed the best results in terms of mechanical properties and dart impact. The films were also characterized thermally via thermogravimetric analysis (TG) and differential scanning calorimetry (DSC), using Fourier-transform infrared spectroscopy (FTIR), and morphologically using a scanning electron microscope (SEM). Other parameters, such as tearing and perforation, were analyzed. Full article

Biomass–fungi biocomposite materials are derived from sustainable sources and can biodegrade at the end of their service. They can be used to manufacture products that are traditionally made from petroleum-based plastics. There are potential applications for these products in the packaging, furniture, and construction industries. In the biomass–fungi biocomposite materials, the biomass particles (made from agricultural waste such as hemp hurd) act as the substrate, and a network of fungal hyphae grow through and bind the biomass particles together. Typically, molding-based methods are used to manufacture products using these biocomposite materials. Recently, the authors reported a novel extrusion-based 3D printing method using these biocomposite materials. This paper reports a follow-up investigation into the effects of mixing parameters (mixing time and mixing mode) on fungal growth in biomass–fungi mixtures prepared for 3D printing and the effects of printing parameters (printing speed and extrusion pressure) on fungal growth in printed samples. The fungal growth was quantified using the number of fungal colonies that grew from samples. The results show that, when mixing time increased from 15 to 120 s, there was a 52% increase in fungal growth. Changing from continuous to intermittent mixing mode resulted in an 11% increase in fungal growth. Compared to mixtures that were not subjected to printing, samples printed with a high printing speed and high extrusion pressure had a 14.6% reduction in fungal growth, while those with a low printing speed and low extrusion pressure resulted in a 16.5% reduction in fungal growth. Full article

Single-use plastic (SUP) is an important product group in plastic pollution with various measures managing it within its lifecycle. Africa has the highest single-use plastic bag (SUPB) policy adoption by region globally, but the plastic problem persists, raising policy design concerns on effectiveness. This paper explores plastic policy design on plastic waste reduction in Africa. Using gap analysis and integrative propositional analysis, the status, scope, and variability of policies are assessed against a reference model. There are 48 active policies in 39 of the 55 countries in Africa. Of these, three countries have transitioned from plastic bag bans to SUP policies to manage more plastic products, and two countries have transitioned from SUPB charges to SUPB bans. There are 12 packaging policies, 29 bag policies, 2 bottle policies, 1 utensil and polystyrene boxes policy, and 1 straw policy. Themed SUP and packaging policies loosely cover plastic products. Four of the nine packaging policies analyzed are SUPB policies by design, as they explicitly mention the control of bags rather than primary packaging. Sixteen policies are designed for biodegradability restrictions, while ten policies are total bans on single-use plastic products. The lack of definitions and coherence and provision of exemptions in policies result in plastic waste traceable from exemptions, in-policy, undefined SUP, out-of-policy SUP, and non-SUP sources. The use of different policy mix instruments to manage plastic within its lifecycle was identified in African countries. The design of new policies should consider these shortcomings to enhance plastic waste management by explicitly identifying products and outlining management measures for excluded plastic products within the same plastic group for SUP or packaging policies in the absence of a global or regionally binding plastic policy. Full article

The need for increased recycling of plastic packaging waste (PPW) is apparent from a legal and waste management perspective and, therefore, further waste streams need to be investigated in detail in terms of their recycling potential. Polyethylene terephthalate (PET) PW is already closed-loop recyclable (bottle-to-bottle recycling); however, other rigid PET PW is mainly thermally recovered. Explicit quantitative and qualitative data on rigid PET packaging waste are limited. Therefore, this study investigates the composition and packaging characteristics of rigid PET packaging waste contained in separate waste collection as well as in the mixed PET sorting stream in Austria by conducting a manual sorting analysis. Furthermore, the waste volume is projected, and the recycling potential is extrapolated according to new European recycling rate reporting formats. The results show that approximately 11% of separate collection represents rigid PET packaging waste. Most PW derives from food packaging and is transparent. Contained residues with more than 1% of the total packaging weight might negatively impact the sortability. The applicable net quantity indicator (ALR) amounts to 0.888 at the stage of sorting. The volume of rigid PET PW is extrapolated to 26–36 kt in 2020 with a high-quality recycling rate of 25%, which contributes 2.6% to the Austrian PPW recycling target of 50%. Full article

Quinoline (QN) is highly toxic and carcinogenic and has been detected in soil, groundwater, and biological tissues. Advanced oxidation processes (AOPs) have shown promise to address its degradation in wastewater treatment, with catalytic wet peroxide oxidation (CWPO) being highlighted due to its cost-effectiveness and mild operation. However, developing active and inexpensive catalysts is crucial for CWPO’s effectiveness. Another pressing issue is the accumulation of mixed, dirty plastic solid waste (PSW), particularly polyolefins used in packaging. Although recycling rates have increased, much plastic packaging remains in landfills. However, polyolefins can be converted into carbon-based nanostructured materials (CNMs), such as carbon nanotubes (CNTs), through chemical vapor deposition (CVD) using PSW as a carbon precursor. While many studies focus on CNT preparation, their application is often overlooked. In this context, this work proposes the preparation of CNMs, particularly CNTs, through CVD using a single-stage pyrolysis reactor. Polyolefins (LDPE, HDPE, and PP), both individually and in a mixture simulating PSW, were used as carbon sources. Given a sufficiently high temperature, the desired CNT architecture was successfully synthesized regardless of the starting polymer. These CNMs were then tested as catalysts for CWPO in simulated wastewater containing QN. The results showed a rapid degradation of QN (30–120 min) and high removals of total organic carbon (TOC) and aromatic compounds (75% and >90%, respectively), demonstrating the applicability of PSW-derived CNTs in the CWPO process for QN abatement. Full article

Polypropylene (PP) is one of the most abundant plastics used due to its low price, moldability, temperature and chemical resistance, and outstanding mechanical properties. Consequently, waste from plastic materials is anticipated to rapidly increase with continually increasing demand. When addressing the global problem of solid waste generation, post-consumer recycled materials are encouraged for use in new consumer and industrial products. As a result, the demand is projected to grow in the next several years. In this study, material recovery facility (MRF)-recovered post-consumer PP was utilized to determine its suitability for extrusion blow molded bottle food packaging. PP was sorted and removed from mixed-polymer MRF-recovered bales, ground, trommel-washed, then washed following the Association of Plastics Recyclers’ protocols. The washed PCR-PP flake was pelletized then manually blended with virgin PP resin at 25%, 50%, 75, and 100% PCR-PP concentrations and fed into the extrusion blow molding (EBM) machine. The EBM bottles were then tested for physical performance and regulatory compliance (limits of TPCH: 100 μg/g). The results showed an increased crystallization temperature but no practical difference in crystallinity as a function of PCR-PP concentrations. Barrier properties (oxygen and water vapor) remained relatively constant except for 100% MRF-recovered PCR-PP, which was higher for both gas types. Stiffness significantly improved in bottles with PCR-PP (p-value < 0.05). In addition, a wider range of N/IAS was detected in PCR-PP due to plastic additives, food additives, and degradation byproducts. Lastly, targeted phthalates did not exceed the limits of TPCH, and trace levels of BPA were detected in the MRF PCR-PP. Furthermore, the study’s results provide critical information on the use of MRF recovered in food packaging applications without compromising performance integrity. Full article

To establish a circular economy, waste streams should be used as a resource to produce valuable products. Biodegradable plastic waste represents a potential feedstock to be microbially recycled via a carboxylate platform. Bioplastics such as polylactic acid food packaging waste (PLA-FPW) are theoretically suitable feedstocks for producing carboxylates. Once feasible, carboxylates such as acetate, n-butyrate, or n-caproate can be used for various applications like lubricants or building blocks for making new bioplastics. In this study, pieces of industrial compostable PLA-FPW material (at 30 or 60 g/L) were added to a watery medium with microbial growth nutrients. This broth was exposed to 70 °C for a pretreatment process to support the hydrolysis of PLA into lactic acid at a maximum rate of 3.0 g/L×d. After 21 days, the broths of the hydrolysis experiments were centrifugated and a part of the supernatant was extracted and prepared for anaerobic fermentation. The mixed microbial culture, originating from a food waste fermentation bioprocess, successfully fermented the hydrolyzed PLA into a spectrum of new C2-C6 multi-carbon carboxylates. n-butyrate was the major product for all fermentations and, on average, 6.5 g/L n-butyrate was obtained from 60 g/L PLA-FPW materials. The wide array of products were likely due to various microbial processes, including lactate conversion into acetate and propionate, as well as lactate-based chain elongation to produce medium-chain carboxylates. The fermentation process did not require pH control. Overall, we showed a proof-of-concept in using real bioplastic waste as feedstock to produce valuable C2-C6 carboxylates via microbial recycling. Full article