A review from Australia summarises different routes for plastics recycling and current technology developments. Plastics recycling is characterised as: Primary = mechanical recycling into an equivalent plastic; Secondary = mechanical down-cycling to a plastic with lower properties or quality; Tertiary = recovery of chemical constituents; Quaternary = waste to energy. New recycling routes however fall outside this categorisation, when contained metals or other elements are recovered at the same time as the organic carbon content: e.g. car tires as fuel for steel production, e-waste as input to metal smelters, use in silicon carbide production. Other innovative recycling routes cited include upcycling e-waste to 3D-printing filaments, to carbon fibre products, to composite panels or to activated carbon for superconductor production.
“The present and future of e-waste plastics recycling”, V. Sahajwalla & V. Gaikwad, Current Opinion in Green and Sustainable Chemistry 2018, 13:102–107 https://doi.org/10.1016/j.cogsc.2018.06.006