Recycling of post-consumer plastic packaging waste in the EU: Recovery rates, material flows, and barriers.

Increasing plastic waste recycling is a milestone of European environmental policy to reduce environmental impacts and dependency on foreign resources. This is particularly challenging for plastic packaging waste, consisting of very heterogeneous fractions and typically rather contaminated. In this study, we collected primary data from plants sorting and recycling plastic packaging waste to illustrate process efficiencies, material flows, and barriers. We observed that significant losses of target materials occurred both at sorting and recycling stages. These were higher for polymers such as films, polypropylene and polystyrene, and lower for polyethylene terephthalate and high-density polyethylene. Applying material flow analysis, we estimated an overall end-of-life recycling rate for post-consumer plastic packaging waste in EU27 in 2017 of 14% (not considering waste exported as recycled; 25% otherwise). An improved scenario for 2030 showed that achieving an overall end-of-life recycling rate of about 49% was possible when best available practices and technologies were implemented. To fulfil the ambitious recycling targets set at EU27 level (55% overall recycling rate), substantial improvements are necessary at the plants, product design, collection system, and market level. Our findings further indicate that films and other problematic contaminants in the input-waste considerably hamper the recovery rates, thus the improvement of the efficiency of the collection systems is imperative. In parallel, the development of markets for lower value fractions, e.g. polypropylene, could be a way forward to increase recycling, while improvements in the product design will considerably reduce the presence of impurities and contaminants in the input-waste.

Dynamic Material Flow Analysis of PET, PE, and PP Flows in Europe: Evaluation of the Potential for Circular Economy.

This study evaluates the potential circularity of PET, PE, and PP flows in Europe based on dynamic material flow analysis (MFA), considering product lifetimes, demand growth rates, and quality reductions of recycled plastic (downcycling). The circularity was evaluated on a baseline scenario, representing 2016 conditions, and on prospective scenarios representing key circularity enhancing initiatives, including (i) maintaining constant plastic consumption, (ii) managing waste plastic exports in the EU, (iii) design-for-recycling initiatives, (iv) improved collection, and (v) improved recovery and reprocessing. Low recycling rates (RR, 13-20%) and dependence on virgin plastic, representing 85-90% of the annual plastic demand, were demonstrated after 50 years in the baseline. Limited improvements were related to the individual scenarios, insufficient to meet existing recycling targets. However, by combining initiatives, RRs above 55%, where 75-90% was recycled in a closed loop, were demonstrated. Moreover, 40-65% of the annual demand could potentially be covered by recycled plastic. Maintaining a constant plastic demand over time was crucial in order to reduce the absolute dependence on virgin plastic, which was not reflected by the RR. Thus, focusing strictly on RRs and even whether and to which extent virgin material is substituted, is insufficient for evaluating the transition toward circularity, which cannot be achieved by technology improvements alone-the demand must also be stabilized.

Plastic waste from recycling centres: Characterisation and evaluation of plastic recyclability.

While recycling has been recognised as the preferred plastic waste management solution, little is known about the detailed characteristics of plastic waste and how these may affect its recycling. In this study hard plastic, plastic film and PVC waste collected at three Danish recycling centres were sampled and characterised according to product applications, legislative requirements (quality), expected product life time, polymer types and presence of potential impurities such as coloured plastics, non-plastic materials and multi-polymer products. The obtained information was applied for estimation of overall recycling potentials for selected archetype recycling process chains based on material flow analysis. In addition to providing detailed data for the composition of the plastic waste products, the results showed that impurities represented 28% (wet weight) of the plastic waste, and that about 75% of the plastic waste was characterised as Low Quality applications, indicating some legislative recovery restrictions. By accounting for the level/type of impurities, the overall recycling potential was found to be 52% for hard plastics, 59% for plastic films and 79% for PVC waste. The results showed that while varying according to polymer type, the recyclability of "High Quality" plastic waste was 12-35% higher than "Low Quality" applications. While actual results are representative of Danish conditions, the study demonstrates that detailed characteristics of plastic waste are needed to identify potential challenges to recycling and thereby potentially improving the design (and recovery efficiency) of recycling facilities.

Temporal and geographical patterns of solid waste collected at recycling centres.

Citizens increasingly dispose their waste at household waste recycling centres (HWRC). To enhance the collection of recyclables materials, local authorities and waste management companies invest considerable resources in planning. While the planning of these centres requires a comprehensive understanding of collected solid waste, only limited studies have consistently investigated waste data from HWRC. To fill this knowledge gap, historical data for HWRC from the Greater Copenhagen, Central Zealand, Silkeborg and Djursland in Denmark were analysed with regards to temporal and geographical variation. The results showed the mass of collected waste varies seasonally; this trend was consistently seen during the period 2010-2016. Moreover, the data revealed that the total waste collected was principally driven by the number of visitors. The geometric bar plot and ternary plot depicted an increase in the percentage of recyclable materials, whereas the percentage of incinerated waste decreased during the period 2010-2016. The waste characterisation study indicated that about 7% of small miscellaneous combustible waste was brought in black plastic bag, although these bags were forbidden; the results suggest that the percentage of misplaced recyclable materials could considerably decrease if citizens bring their waste in clear plastic bags.

Combustible waste collected at Danish recycling centres: Characterisation, recycling potentials and contribution to environmental savings.

Europe is currently adapting its waste management strategies towards the increased recycling of waste materials, motivated by ambitious recycling targets. This requires correctly sorting and recovering of all relevant waste flows. In Denmark, a considerable share of residential household waste is collected at recycling centres, 16% of which is sent to energy recovery in the form of "small combustible waste". Although essential in order to enhance the management of household waste, very little information exists on its composition. In this study, 25 tonnes of small combustible waste were sampled from eight Danish recycling centres and classified according to material fraction, application and physical properties. On this basis, the potential contribution to the overall recycling rate was evaluated together with estimation of the potential environmental savings associated with recycling of these fractions. Less than half of the sampled waste comprised combustible materials, whereas recyclable fractions accounted for 47-64%, mainly including textiles, plastics and paper waste. Assuming this composition applicable to the national level, recycling these waste materials collected as small combustibles increased national recycling rates for households by 12%, calculated as waste received at recycling processes. Moreover, the potential climate change savings associated with recycling of Danish household waste increased by 30% compared to the current level. Plastics, textiles and paper were the main contributors to this increase, suggesting that improved sorting practices for these materials should be prioritised. The study demonstrates that detailed compositional data for waste materials has paramount importance when estimating recycling potentials and quantifying the associated environmental benefits.

Resource quality of wood waste: The importance of physical and chemical impurities in wood waste for recycling.

Recycling of post-consumer wood waste into particleboard may be hindered by the presence of physical and chemical impurities in the waste stream, therefore calling for increased attention on the quality of wood waste. However, wood waste comprises several uses/types of wood, along with different levels of contamination. This study provides the detailed sampling and characterisation of wood waste according to its source, type and resource quality grade. Eight tonnes of wood waste, intended for recycling and collected at three Danish recycling centres, were subdivided into 34 individual material fractions and characterised with respect to the presence of three classes of physical impurities (misplacements, interfering materials and low-quality wood waste) as well as chemical concentrations of more than hundred chemical elements and persistent organic pollutants (POPs). The results demonstrated that contaminant and concentration levels vary significantly according to wood waste type and source, thus emphasising that wood waste should not be viewed as a single material flow but rather be understood and managed according to the presence of individual fractions. Including only clean wood waste fractions at the three recycling centres, 41-87% of the collected wood waste per weight could be recycled - the rest being physical impurities. The results showed that chemical contamination was significantly higher for low-quality wood waste, thus clearly indicating that improvements in separate collection, sorting and handling of wood waste may improve the resource quality of wood waste and potentially achieve cleaner recycling practices.

Dynamic accounting of greenhouse gas emissions from cascading utilisation of wood waste.

Cascading utilisation of post-consumer wood waste has recently gained increasing attention in the European Union, aiming for a society in which the resource's properties are optimized through sequential uses. To date, material utilisation of wood waste has been limited to particleboard production, with additional niche alternatives being restricted by quality requirements for wood waste. In this consequential life cycle assessment focusing on post-consumer wood collected at Danish recycling centres, Global Warming Potential (GWP) impacts from quality-driven choices for cascading management of wood waste were compared with those from handling mixed wood waste qualities. GWPs were modelled by considering the dynamic profile of greenhouse gas emissions (including biogenic carbon dioxide) for two time horizons (100 and 500 years). The robustness of the results was tested by varying modelling assumptions with respect to electricity system, wood sourcing and associated rotation period, and impacts from indirect land use changes. The results demonstrated that valuing quality over quantity in wood waste management can ensure larger GWP savings, especially if recycling applications have a long lifetime and/or substitute energy-intensive products; such results were confirmed under all scenario analyses. Inclusion of land use changes credited land-intensive products. More cascade steps of the wood waste resource ensured larger savings; however, assumptions on the electricity mix, on the source of the wood alongside the choice of the time horizon for GWP greatly influenced the results on cascading management.