The results, which also showed that PET sheet made from the recycled resin produced by the tests was not contaminated, were given to Plastics News on June 30 by bioplastics manufacturer NatureWorks LLC and Primo Water Corp., which packages water in PLA bottles.

Recyclers still are not convinced. Some said the tests were not conducted under real operating conditions, that the level of PLA bottles sorted out was not high enough, and that PLA bottles still have the potential to decrease their already shrinking yields and decrease efficiency of their PET recycling processes.

“I’m not sure that this answers all the questions recyclers have about PLA and its potential to contaminate the PET recycling process,” said Steve Alexander, executive director of the Association of Postconsumer Plastic Recyclers in Washington.

“There are a lot of different types of technologies out there, and they ran all their tests using one technology, near infrared, and not all recyclers use that technology,” he said.

Many PET recyclers use a Vinyl Cycle detection system from National Recovery Technologies Inc. of Nashville, Tenn., and do not use NIR technology. NIR systems, which cost upwards of $200,000, are typically used by larger materials recovery facilities and waste haulers.

The tests were conducted for NatureWorks and Primo and verified by the independent consulting firm Plastics Forming Enterprises LLC. They used a NIR machine from TiTech VisionSort GmbH, based in Oslo, Norway.

About 75 pounds, or 1,500 Primo Water bottles, without caps or labels, were flattened and added to a load of PET deposit bottles weighing approximately 35,000 pounds. That volume was selected to mimic conditions if Primo had the fourth highest market share in water bottles.

The tests, most of which were conducted earlier this year, found that 93 percent of the PLA was separated out and that there was “no appreciable color or haze difference” between sheet samples made from a control batch made from recycled PET resin and two sample sheets that contain PLA that was not separated out during sorting, said Brian Glasbrenner, NatureWorks business director for the Americas for beverage, film and cards.

“I’m confident in the testing and that this will get a large chunk of folks who have been neutral or against us on our side, supporting us,” Glasbrenner said. “This was not a lab-scale or staged test, but tests that were done at a full-scale commercial facility that was operating under normal conditions. We think it is a very fair, very realistic, very robust test. We used a reasonable amount of bottles and were able to verify the results through a third-party.”

But several recyclers disagreed.

For starters, one technical expert at a PET recycler said that clarity depends on the thickness of the plaques and that samples were only measured across three different thicknesses.

Another recycler pointed that adding the PLA bottles without caps or labels and only using bales collected from deposit programs do not simulate real-life conditions, as baled material contain both caps and labels as well as other plastics such as PVC. “Because the machine is getting a clearer look at the bottles, you get half the error rates,” he said.

He also called the 93 percent sorting rate unacceptable.

In addition, the tests do not address whether PLA that made it through the sorting equipment ended up being removed in the drying process — something that recyclers say is a common problem with contaminants.

Tim Ronan, senior vice president of marketing for Primo Water, said he did not have information about contamination levels in the dryers. “I am not sure about that,” he said. “We never talked about it. It wasn’t part of the report. The dryer part never came up, so I am assuming it is not an issue.”

Similarly, Ronan said Natureworks and Primo were assured by the consulting firm, PFE, that there was no need to include caps or labels on the PLA bottles.

“What we were able to do in a real setting in a commercial facility was prove that PLA can be sorted and recycled under normal recycling conditions in the systems that are used today,” Ronan said. “That should help recyclers be positive about the recycling of PLA, because if they have the right equipment, the opportunity is there to keep the bale as clean as possible.”

One recycling executive scoffed at that notion.

“The premise they are trying to support — that you should let PLA be collected with PET — is absolutely preposterous,” said the reclaimer. “To say that PET recyclers will gladly accept it because they can get it out is ridiculous,” particular when there currently is no market for recycled PLA and it would be an added cost for reclaimers to separate it and landfill it.

What’s more, he pointed out that even today reclaimers are challenged by the amounts of PET — in the range of 5 percent or more — than are sorted out by systems designed to separate other materials from PET. “It is a sizeable amount and they can’t afford to let that stuff be thrown away. This could potentially separate more PET from the process” if additional equipment were added to sort PLA, he said.