Quality of recycling: Urgent and undefined

Critical properties of plastic packaging waste for recycling: A case study on non-beverage plastic bottles in an urban MSW system in Austria

The low recycling rate of post-consumer plastic packaging waste (PPW), which is partly due to insufficient separate collection, heterogeneous composition and high levels of contamination, poses a challenge in Austria, where the recycling rate must double in order to meet the target of 55 %. This study analyzes key packaging characteristics of non-beverage plastic bottles influencing recyclability, using Vienna as a case study. Additionally, a net quantity indicator and separate collection rates were calculated. 738 bottles from mixed MSW and 1,159 bottles from separate PPW collection were analyzed. The main polymer's proportion described by the net quantity indicator was higher for bottles from separate collection (69-72 %) than from mixed MSW (58 %), showing that a large share of the foreign materials are residues and dirt, with significantly higher contents in mixed MSW (20 %) than in separate collection (11 %). With a separate collection rate of 19.2 %, the great potential for recycling currently lies in mixed MSW at 4,112 t/yr. Thereof, 46 % is uncolored, 54 % is colored/white and, in terms of material grade, 30 % is food grade. The most common filling volume for PET, PP and HDPE was 0.5 < x ≤ 1.5 L (23-59 %) and the most common decoration technology was label (60-85 %). PET and PP had the highest shares of food-grade bottles (37-46 %), while PP had the highest share of colored bottles (22-31 %). The mechanical recycling potential of bottles depends largely on packaging characteristics, influencing separate collection and also automatic sorting. Harmonized design specifications are therefore crucial for this heterogeneous PPW fraction.

Mechanical recycling of printed flexible plastic packaging: The role of binders and pigments

Low-density polyethylene (LDPE), extensively employed in flexible plastic packaging, often undergoes printing with inks. However, during the mechanical recycling of post-consumer waste, these inks act as contaminants, subsequently compromising the quality and usability of recycled material. To understand better exactly which ink components cause which effects, this study comprehensively assesses the thermal behavior of three organic pigments and two commonly utilised binders, correlated with the impact on the mechanical recycling of LDPE-based flexible plastic packaging. In this regard, the study focuses on four pivotal factors: processability, mechanical properties, aesthetic attributes, and volatile organic compound profiles. The results indicate that nitrocellulose, used as a binder, degrades during reprocessing, resulting in film discoloration and the emission of potentially odorous compounds. Conversely, pigments are found to be dispersed within droplets of polyurethane binder in LDPE recyclates, whilst reprocessing printed samples detrimentally affects film properties, notably dart drop impact resistance, strain at break, and the number of inclusions. Additionally, it is shown that both inks comprise components that emit volatile compounds during reprocessing: non-thermally stable components, nitrocellulose and pigment yellow PY13, as well as low-molecular weight molecules from polyurethane and by-products from wax, plasticisers, and additives.

Life cycle assessment of pharmaceutical packaging addressing end-of-life alternatives

Pharmaceutical packaging waste has increased due to a higher global demand for pharmaceutical products, leading to more waste generation and associated environmental impacts. The main goal of this article is to present a cradle-to-grave life cycle assessment of pharmaceutical packaging, evaluating end-of-life (EoL) alternatives, aiming to identify hotspots and opportunities for improvement. A life cycle model was implemented for three types of pharmaceutical packaging (blisters, sachets, bottles; 23 packaging). The functional unit is the storage and delivery of medicines containing the same active pharmaceutical ingredient, dosage, and amount of medicines. Two EoL analyses were performed: 1) compare take-back (recycling and incineration) with domestic waste collection (landfill or incineration); and 2) assess different EoL situations of pharmaceutical packaging in Europe. A life cycle impact assessment was performed for 13 categories. Analysis 1 shows that take-back presents lower environmental impacts than domestic waste collection for seven out of 13 categories due to paper and glass recycling benefits. Analysis 2 shows that in the take-back, higher amounts of packaging are recycled or incinerated, which leads to lower EoL impacts. A sensitivity analysis was performed to evaluate the influence of parameters and assumptions in packaging EoL impacts. Packaging production contributes significantly to life cycle impacts, followed by transportation, EoL, and packing process. Ecodesign initiatives are recommended, such as packaging with less material and volume, using materials with lower impacts to significantly reduce the impacts of pharmaceutical packaging.

Environmental and socio-economic effects of construction and demolition waste recycling in the European Union

The recovery rate of construction and demolition waste (CDW) in the European Union (EU) is at 89 % and thus high relative to other waste streams. However, the relatively high figure can be misleading because it typically does not correspond to high-value material recovery but rather "poor" levels of circularity. From a life-cycle perspective, we assess the environmental impacts and costs of 12 CDW material fractions relying on alternative pathways and treatment technologies. The results indicate important trade-offs in the transition towards the circular economy. Indeed, recycling of concrete, bricks, gypsum, and ceramics and tiles represent the best environmental performance but also the most expensive pathway. However, when shifting from landfill to recycling the total societal costs in the EU are reduced mainly due to the lower external costs. Overall, recycling CDW in the EU with advanced technologies would save about 264 kg CO2-eq t-1 with a cost of 25 EUR t-1. The maximum potential for recycling under current technology in the EU would lead to an annual total reduction of about 33 Mt. of CO2-eq using 2020 as reference year. The fractions with the highest potential for improving current waste management practices in terms of environmental improvements are concrete and bricks. The economic and non-economic barriers for realising this potential at EU level are discussed in relation to the European Green Deal and the EU's circular economy objectives.

Management practices for compostable plastic packaging waste: Impacts, challenges and recommendations

The EU Green Deal aims at solving the challenges related to plastic production, (mis-)use, and pollution. While the bioplastic industry is identified as one of the possible avenues to tackle the problem, bioplastic waste collection and management practices are still far from full-development and harmonisation. To inform policy makers on the best practices and their feasibility, this study quantifies environmental and economic impacts of compostable plastic packaging (CPP) waste management schemes by means of Life Cycle Assessment and Costing. Results show that, with respect to climate change and financial costs, the scheme leading to the highest benefits is collecting CPP with conventional plastic waste followed by mechanical sorting and recycling (saving ca. 306 kg CO2eq. t-1 at a net income of 3.7 EUR t-1). The second best option is collecting CPP with bio-waste followed by biological treatment (saving ca. 69 kg CO2eq. t-1 at a cost of 197 EUR t-1). Collecting CPP with conventional plastics followed by sorting and biological treatment is to be avoided. The trend on the other impact categories generally follows climate change. Ideally, closed loop is therefore preferred, but conditioned by (i) having high share of CPP in municipal waste (else sorting is economically unfeasible), (ii) good citizen's behaviour at source-segregation, and (iii) an established market for secondary material. Currently, overall benefits are limited by the low amounts, suggesting that the management choice could ultimately be based on rather simple technical and economic feasibility criteria while regulatory and management efforts should be focused on other waste streams with greater implications on environment.

Operational Framework to Quantify "Quality of Recycling" across Different Material Types

Many pledges and laws are setting recycling targets without clearly defining quality of recycling. Striving to close this gap, this study presents an operational framework to quantify quality of recycling. The framework comprises three dimensions: the Virgin Displacement Potential (VDP); In-Use Stocks Lifetime (IUSL); and Environmental Impact (EI). The VDP indicates to what extent a secondary material can be used as a substitute for virgin material; the IUSL indicates how much of a certain material is still functional in society over a given time frame, and the EI is a measure of the environmental impact of a recycling process. The three dimensions are aggregated by plotting them in a distance-to-target graph. Two example calculations are included on poly(ethylene terephthalate) (PET) and glass. The results indicate that the recycling of bottle and container glass collected via a deposit-refund system has the lowest distance-to-target, at 1.05, and, thus, the highest quality of recycling. For PET bottles, the highest quality of recycling is achieved in closed-loop mechanical recycling of bottles (distance to optimal quality of 0.96). Furthermore, sensitivity analysis indicates that certain parameters, e.g., the collection rate for PET bottles, can reduce the distance-to-target to 0.75 when all bottles are collected for recycling.

Technical substitutability of recycled materials in life cycle Assessment: A comprehensive review and framework for quantification

In evaluating environmental sustainability with methodologies like life cycle assessment (LCA), recycling is usually credited for avoiding impacts from virgin material production. Consequently, the LCA results are influenced by the manner in which the substitutability of virgin by recycled materials is estimated. This study reviews how the scientific community assesses the technical substitutability of recycled materials in LCA. Accordingly, 49 peer-reviewed papers were in-depth analysed, considering aspects such as materials studied, type of substitution, recycled material (rMaterial) application, and life cycle stages (LCSs) where substitution was evaluated. The results show that 49% of the papers investigated material substitutability through technical and economic aspects. 51% of the articles did not consider the final application of the rMaterial. Plastics were the most studied material, and mass was the most used property to quantify technical substitutability. Certain materials were more analysed in specific LCSs (e.g., metals in the natural resource extraction stage). As 51% of the papers developed a new approach for substitutability calculation, this shows that substitutability is still a concept in development. It was noticed in 33% of the papers that substitutability values were taken from external sources, and in some cases were used without considering whether they were representative for a specific case. Aspects such as harmonization, transparency, and consideration of the application of recycled materials, therefore, require more attention in substitutability evaluation. Based on the results, a step-wise framework to measure technical substitutability at different LCSs was developed to guide researchers in including substitutability in LCA studies.

Polyolefin Recyclates for Rigid Packaging Applications: The Influence of Input Stream Composition on Recyclate Quality

In order to shift to a circular plastics economy, high quality recyclates are required to effectively substitute virgin materials. Current approaches to empirically quantify the substitutability for recyclates are mainly limited by the abundance of virgin material grades along with a lack of adequate application-specific property profiles. In contrast, this work aims for a holistic analysis of the substitution potential of polyolefin recyclates intended for rigid packaging applications. This approach is fundamentally based on the classification of virgin polyolefins into different application-specific sub-groups with defined property windows derived from supplier data sheets, which allows for a generalization within one polymer type without neglecting the various available material grades. Moreover, the findings should provide valuable information for improvements of quality-defining process steps along the value chain of mechanical recycling. Therefore, it is of great importance to correlate the input stream composition of the investigated recyclates with the obtained qualities. The investigation of the substitution potential for selected recyclates clearly highlights the necessity of functional recycling for enhanced quality levels, which especially affects the sorting step in the recycling value chain. This work illustrates that a homogeneous waste stream directly correlates with a high substitution potential. Thus, the development of economically viable sorting strategies which take the functionality of plastic waste products into account must be targeted in future research. Furthermore, the development of detailed application-specific property windows in a joint effort with manufacturers should be pursued, as it allows for a meaningful empirical quantification of the substitutability for recyclates obtained from mechanical recycling.

Thermal pyrolysis of waste versus virgin polyolefin feedstocks: The role of pressure, temperature and waste composition

Due to the complexity and diversity of polyolefinic plastic waste streams and the inherent non-selective nature of the pyrolysis chemistry, the chemical decomposition of plastic waste is still not fully understood. Accurate data of feedstock and products that also consider impurities is, in this context, quite scarce. Therefore this work focuses on the thermochemical recycling via pyrolysis of different virgin and contaminated waste-derived polyolefin feedstocks (i.e., low-density polyethylene (LDPE), polypropylene (PP) as main components), along with an investigation of the decomposition mechanisms based on the detailed composition of the pyrolysis oils. Crucial in this work is the detailed chemical analysis of the resulting pyrolysis oils by comprehensive two-dimensional gas chromatography (GC × GC) and ICP-OES, among others. Different feedstocks were pyrolyzed at a temperature range of 430-490 °C and at pressures between 0.1 and 2 bar in a continuous pilot-scale pyrolysis unit. At the lowest pressure, the pyrolysis oil yield of the studied polyolefins reached up to 95 wt%. The pyrolysis oil consists of primarily α-olefins (37-42 %) and n-paraffins (32-35 %) for LDPE pyrolysis, while isoolefins (mostly C₉ and C₁₅) and diolefins accounted for 84-91 % of the PP-based pyrolysis oils. The post-consumer waste feedstocks led to significantly less pyrolysis oil yields and more char formation compared to their virgin equivalents. It was found that plastic aging, polyvinyl chloride (PVC) (3 wt%), and metal contamination were the main causes of char formation during the pyrolysis of polyolefin waste (4.9 wt%).

Information-Based Plastic Material Tracking for Circular Economy-A Review

At the moment, it looks like the plastics recycling industry is skimming only low-hanging fruits of its business. To reach intended targets, a greater effort and disruptive innovations are necessary. Physical- or digital-information-based solutions for tracking plastic material can support the circular economy and help to overcome hurdles along the value chain. In this paper, the scientific literature and initiatives in four different technology areas for information-based tracking solutions are reviewed and analyzed. Physical markers can improve sorting efficiencies on short notice but adhere some technical difficulties. Blockchain as a new concept promises high transparency and security, with the drawbacks of energy-intense verification and technical uncertainties. As a third group, the digital product passport claims a combination of physical and digital solutions with open questions on data ownership. The fourth and last group includes standards and certification systems that aim for maximum consensus with slow market implementation. To enable an integrated circular economy of plastics, plastic material tracking solutions must experience broad acceptance by all players along the value chain in the plastics industry and they should additionally be supported by society.