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Highlights Indicators are useful to support circular economy progress. Circular economy has different definitions entailing challenges for indicators. A classification framework to understand what indicators measure is proposed. Most of the analysed indicators focus on the preservation of materials. None of the analysed indicators focuses on the preservation of functions.

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A two-step aqueous alkaline hydrolysis was carried out on different types of real PET plastic waste under mild conditions.

Microplastics are ubiquitous pollutants within the marine environment, predominantly (> 90 %) accumulating in sediments worldwide. Despite the increasing global concern regarding these anthropogenic pollutants, research into the remediation of microplastics is lacking. Here, we examine those characteristics of microplastics that are essential to adequately evaluate potential remediation techniques such as sedimentation and (air) flotation techniques. We analyzed the sinking behavior of typical microplastics originating from real plastic waste samples and identified the best-available drag model to quantitatively describe their sinking behavior. Particle shape is confirmed to be an important parameter strongly affecting the sinking behavior of microplastics. Various common shape descriptors were experimentally evaluated on their ability to appropriately characterize frequently occurring particle shapes of typical microplastics such as 1 Page 1 of 38 ACS Paragon Plus Environment Environmental Science & Technology spheres, films and fibers. This study is the first in this field to include film particles in its experimental design, which were found to make up a considerable fraction of marine pollution and are shown to significantly affect the evaluation of shape-dependent drag models. Circularity χ and sphericity Φ are found to be appropriate shape descriptors in this context. We also investigated the effect of biofouling on the polarity of marine plastics and estimated its potential contribution to the settling motion of initially floating microplastics based on density-modification. It is found that biofouling alters the polarity of plastics significantly, this is from (near) hydrophobic (i.e. water contact angles from 70 to 100°) to strong hydrophilic surfaces (i.e. water contact angles from 30 to 40°) rendering them more difficult to separate from sediment based on polarity as primary separation factor. Thus, next to providing a better understanding of the fate and behavior of typical marine microplastics, these findings serve as a fundamental stepping stone to the development of the first large-scale sediment remediation technique for microplastics to answer the global microplastic accumulation issue.

The Dutch post-consumer plastic packaging recycling network has been described in detail (both on the level of packaging types and of materials) from the household potential to the polymeric composition of the recycled milled goods. The compositional analyses of 173 different samples of post-consumer plastic packaging from different locations in the network were combined to indicatively describe the complete network with material flow analysis, data reconciliation techniques and process technological parameters. The derived potential of post-consumer plastic packages in the Netherlands in 2014 amounted to 341 Gg net (or 20.2 kg net.cap.a). The complete recycling network produced 75.2 Gg milled goods, 28.1 Gg side products and 16.7 Gg process waste. Hence the net recycling chain yield for post-consumer plastic packages equalled 30%. The end-of-life fates for 35 different plastic packaging types were resolved. Additionally, the polymeric compositions of the milled goods and the recovered masses were derived with this model. These compositions were compared with experimentally determined polymeric compositions of recycled milled goods, which confirmed that the model predicts these compositions reasonably well. Also the modelled recovered masses corresponded reasonably well with those measured experimentally. The model clarified the origin of polymeric contaminants in recycled plastics, either sorting faults or packaging components, which gives directions for future improvement measures.

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