[Sindisil]

> 1) Do you need to separate types of plastics or clean them before using this process?

The whole second section of the article discusses this process on mixed plastics, including:

> Another test involved introducing different plastics, such as PET and PVC, to polypropylene and polyethylene to see if that would make a difference. These did lower the yield significantly. If this approach is going to be successful, then all but the slightest traces of contaminants will have to be removed from polypropylene and polyethylene products before they are recycled.

[underdeserver]

I guess it does hint that litter, food waste etc. are also problematic. Could be clearer though.