Sorting multilayer packaging is still a major challenge in the recycling of post-consumer plastic waste. In a 2019 Germany-wide field study with 248 participants, lightweight packaging (LWP) was randomly selected and analyzed by infrared spectrometry to identify multilayer packaging in the LWP stream. Further investigations of the multilayer packaging using infrared spectrometry and microscopy were able to determine specific multilayer characteristics such as typical layer numbers, average layer thicknesses, the polymers of the outer and inner layers, and typical multilayer structures for specific packaged goods. This dataset shows that multilayer packaging is mainly selected according to the task to be fulfilled, with practically no concern for its end-of-life recycling properties. The speed of innovation in recycling processes does not keep up with packaging material innovations.

The increasing consumption of plastics and plastic products results in correspondingly substantial volumes of waste, which poses considerable environmental burdens. With the ongoing environmental actions, the application of circular economy on this waste stream is becoming inevitable. In this paper, the topics of plastics recycling, circular economy on plastics, and challenges to plastic waste recycling are critically reviewed. In the first part of this paper, the development of research on plastic recycling was viewed from 1950 until 2020 using the scientific database Web of Science, and 682 related studies were found and used to assess the changing research priorities along that timeline. The following sections discuss the potentials and requirements to enhance the quality of the produced recycled plastic, in connection with the factors that currently limit it. In conclusion, the quality of recycled plastic is generally determined by the homogeneity of the recovered plastic feed. There are various strategies which could be implemented to overcome the hindrances identified in the paper and to improve the quality of the recycled plastic, such as working on enhanced product designs for minimised waste heterogeneity and controlling the materials’ degree of contamination by applying advanced sorting.

The concept of circular economy supports mitigation of climate change and other environmental pressures to the planet. Circulating materials in anthropogenic processes come with the risk of accumulating hazardous substances and compounds. In this concept, waste incineration or waste-to-energy (WtE) is a necessary technology to remove these compounds from the life cycle. In this mini-review, contaminants of major importance in the flue gas from waste incineration plants and their environmental impact are discussed. Air pollution of WtE is often seen as the most relevant environmental impact of this treatment option. The emission values parameter set for different countries is presented and compared. The most stringent legally set of emission values could be found in parts of Europe and South Korea. Japan also permits similar strict values when authorising individual incineration plants. In North America, the values are partially less strict as the best available technologies in Europe suggest being possible. Emerging economies, such as India and China, have shown efforts to improve their environmental protection standards but still have room to improve. This could be set in relation to other industrial emitting processes and therefore could be used to assess the relevance of this industry sector to the national emission inventories.