The recycling of polylactic acid bioplastics may still be in its early stages, but it appears to be heading in the right direction.
The Washington-based Sustainable Biomaterials Collaborative hosted a webinar on the topic March 19. The issue has been in the spotlight more as bioplastics use increases, bringing with it concerns about bioplastics mixing with more commonly recycled plastics.
NatureWorks LLC marketing director Steve Davies identified several obstacles facing PLA recycling, including identification, sortation, volumes, end markets and avoiding contamination of existing recycling streams.
To avoid contamination, Davies said that Minnetonka, Minn.-based NatureWorks has been selling into markets where potential for contamination is minimal.
“We're targeting [applications] with little or no recycling,” he said. “We haven't taken on any new bottle customers recently, and we're working to develop end markets for recycled PLA.”
In 10 years of operation, NatureWorks has recovered about 25 million pounds of off-grade PLA resin and converted it back into lactic acid feedstock. That material then has been polymerized back into resin and resold.
Davies also cited a recent bale-sort audit by the Association of Postconsumer Plastic Recyclers that found a PLA level of only 0.4 percent per bale at most.
Mike Centers is a true believer in PLA recycling, having founded BioCor LLC in Concord, Calif., in 2010. Last year, BioCor converted 230,000 pounds of PLA back into lactic acid and 600,000 pounds into recycled PLA. The recycled PLA amount was 15 times more than what the firm produced in its first year of operation, while the lactic acid conversion total was 35 percent higher.
BioCor is involved in post-industrial recycling of PLA yogurt cups and gift cards, as well as a state-funded effort to recycle PLA food-service items from O.co Coliseum in Oakland, Calif., home to the city's pro sports teams.
“The packaging materials used today won't be the ones used five, 10 or 15 years from now,” Centers said. “The packaging of choice will be plant-based. But the industry needs an economic reason to recycle PLA.”
The PLA sorting issue was addressed by French equipment maker Pellenc SA, which conducted a test in California that showed optical sorting technology can separate PLA from other plastics in a recycling stream.
Alain Descoins, Pellenc's North American CEO, said that a portable container line sorting system was able to separate PLA 97-98 percent of the time during tests conducted by his firm. He said the line can be programmed to identify other bioplastics.
A successful PLA recycling model recently was created at the University of Wisconsin-Stevens Point.
The university began buying PLA food-service items in fall 2009 to replace polystyrene foam products, but had no source segregation or industrial composting available for PLA, according to Paul Fowler, executive director with the Wisconsin Institute for Sustainable Technology.
A PLA recycling effort there collected PLA items from university residence halls and cafeterias, as well as from convenience stores and nearby businesses.
“We started to gather clear cups and clamshells, because we wanted to divert as much [PLA] material as possible,” Fowler said.
The used PLA items then were taken to a chemical recycling site in Eau Claire, Wis., about 90 miles away. Fowler said the results of the program will be studied to measure its impact on recycling streams and the success of its marketing campaign.
“We want to understand what the best end-of-life option is for bioplastics,” he added.