Pyrolysis: a Possible Solution for Contaminated Recyclables

What happens when a #7 gets mixed up with a batch of #1 or #2 recyclables? It contaminates the whole batch. Plastics may start with the same basic ingredient of crude oil, but they become bound differently with the addition of polymer combinations that make a plastic girder feel and act differently from stretch pants.

In the past, recycling employees would have to sort through what people have sent, to separate each numbered class of plastic by hand. Then, depending on the type, plastics are mechanically shredded or subjected to baths of chemicals and water. 

Around 2020 recycling plants began to skip the sorting by using pyrolysis – putting all plastics in a specialized anaerobic incinerator that melts it all down and separates the contaminates from the oils. Then it goes through another process called BTX Recovery that breaks the oil itself into individual petrochemicals again to be resold and reused. 

With more and more recycling centers moving to this technology, the problem of contamination is being solved.