According to an article on Designboom.com the process, called VolCat recycling, collects plastic bottles, containers, and PET-based fabrics, grinds them up, and combines them with a chemical catalyst in a pressure cooker set to above 200 degrees celsius.
VolCat begins by heating PET and ethylene glycol in a reactor with the catalyst. after depolymerization is complete, the catalyst is recovered by distillation from the reactor using the heat of reaction. the solution is filtered, purified, and then cooled, and the solid monomer product is recovered by filtration. the recovered liquid, along with the catalyst, is then reintroduced into the depolymerization reactor in an energy-efficient cycle.
with heat and a small amount of pressure, the catalyst is able to digest and clean the ground-up plastic. the process separates contaminants like food residue, glue, dirt, dyes, and pigments from the material that is useable for new PET. the useable matter (called a monomer) takes the form of a white powder, which can be fed directly into a polyester reactor to make brand new plastics.