PLA sorting for recycling debated
NatureWorks LLC has announced that bottles made from polylactic acid (PLA), the corn-derived plastic of which it is the top U.S. producer, can be identified by these systems with accuracy approaching 100%. This issue is significant because PLA is incompatible with most petroleum-derived plastic, especially polyethylene terephthalate (PET), to the point where its presence during processing can ruin a batch of PET.
In a news release, NatureWorks claims that in a two-year study, it identified a dozen companies offering systems that can potentially distinguish PLA from mainstream plastics. It worked with three of these to ascertain accuracy rates: two using near-infrared technology and one using a laser system. Accuracy in these studies ranged up to 99%.
However, the Association of Post-Consumer Plastics Recyclers cautioned that technology alone does not make PLA sorting economically feasible. Isolating a stream of PLA or any other non-mainstream polymer makes economic sense only if that polymer is valuable enough to be worth separating, says David Cornell, the association’s technical director.
“To dedicate one of these machines to do the sorting for only a few bottles is very expensive,” Cornell says. “The material that you’re removing needs to pay for itself.”