You can recycling PET bottles, beer cans and similar round shapes objects (junk) to thread.
Basically recycling means: to treat things (junk) so that they can be used again.
Thread is a raw material for production, usually for sewing or making fabric or some similar things.
PET is very strong material. 1.5mm PET thread can hold 5kg at least (I don't know exactly).
A 2l PET bottle can be recycled to 3mm thread 20m long.