There is a widespread misconception about compostable plastics and their allegedly negative impact on mechanical recycling streams.
Currently, only a limited number of plastics are sorted for recycling, those are in general the plastics with the highest market shares, such as PET, PP, PE and, in specific cases, also PS. Examining the input streams of sorting facilities, it is clear that several other types of polymers are entering the facilities, which – due to low volumes – will not be recycled and have to be sorted out. Hence, potential cross-contamination of recycling streams is a general issue that involves all kinds of plastics and materials, not only compostable plastics specifically.
Existing sorting technologies, such as density separation and NIR (near-infrared) sorting, can efficiently separate and sort different kinds of polymers, including compostable plastics.
Should compostable plastics, alongside other impurities, enter the recycling streams of PE or PET, no negative impacts are to be expected.