I read this as using materials that would otherwise become landfill waste. econyl website indeed says they get the waste material from all over the world. It is cleaned and then chemically reverted to (manufacturing) monomers, then re synthesized as nylon with original chemistry. They are not describing the process behind intellectual property walls. Interesting to note that nylon and polyurethane are the only large volume plastics that contain nitrogen. Comes up in biodegradation discussions.
