New research suggests that biodegradable polylactide (PLA) bottles can be easily segregated from PET bottles in the waste stream, a point that strengthens the environmental claims of the material.
The study, conducted by National Recovery Technologies (NRT), shows that polylactide (PLA) bottles can be segregated from PET bottles as part of a fraction that is already being removed by reclaimers using NRT infrared machines.
"Because the NatureWorks PLA will likely be in the same stream as common items like salad dressing bottles, vegetable oil bottles, mouthwash and other plastics like PVC, we anticipate that existing NRT infrared machines will not need to be modified to separate PLA from the PET stream," said John Thomsen, engineering manager at NRT, a world leader in plastic mass-sorting technology.
"We also think that the PLA can be distinguished from PVC and other non-PET polymers, but further validation isn't warranted until larger post-consumer quantities of PLA bottles are available."
NaturalWorks PLA, developed by chemical giant Cargill, is increasingly being used by food and beverage packagers keen to package products in biodegradable containers.
Indeed, many analysts believe that biodegradable packaging has a bright future. Growing environmental awareness and consumer power coupled with the inexorable rise in pre-packaged disposable meals means that food manufacturers and packagers are increasingly being targeted to improve their environmental performances.
Datamonitor statistics show that more than one-third of European consumers live alone and are spending €140 billion a year on food, drinks and personal care products. Single people spend 50 per cent more per person on consumer-packaged goods than a two adult household. Such trends underline why the environmental impact of food packaging has never been greater.
The concept behind NaturalWorks is relatively simple. Cargill essentially "harvests" the carbon from corn, which plants remove from the air during photosynthesis and store in grain starches. This is achieved by breaking down the starches into natural plant sugars.
The carbon and other elements in these natural sugars are then used to make plastic, called polylactide (PLA), through a simple process of fermentation, separation and polymerisation. Packaging made from NatureWorks is therefore 100 per cent nature-based.
The NRT data is consistent with other studies using infrared technology to sort NatureWorks PLA from the PET stream. Testing in December 2002 by Nashville-based MSS using its high-capacity Aladdin System found that NatureWorks PLA has a unique signature in the near-infrared (NIR) spectrum, allowing the polymer to be distinguished from PET and other plastics.
And in May 2004, TiTech VisionSort in Borken, Germany, also evaluated the separation of PLA from PET by request of Recycle America Alliance, a venture launched by Waste Management in 2003. It too found that PLA has a very unique IR scan and its Auto Sort equipment was able to separate NatureWorks PLA bottles and fragments from a stream that included PP, PET, PETG, PC, PS, EPS and ABS at standard efficiency rates.
"We are pleased to be getting validation from the recycling industry's leading sort system manufacturers that NatureWorks PLA can be separated from the post-consumer PET stream, and can likely be separated into its own stream when post-consumer amounts warrant such a move," said Brian Glasbrenner, business development manager for PLA bottles.
"We will continue to work with the appropriate associations and industry experts to evaluate the disposal impact of PLA in all waste management systems."
In addition to its fit with the recycling stream, PLA has been successfully composted in applications where that disposal method is desired and commercial composting infrastructure is in place, and it has been reviewed by the Biodegradable Products Institute (BPI) and is listed as positive for compostable materials.
The multiple disposal alternatives of PLA mean that it can play a key role in landfill diversion. In addition to its ability to be mechanically recycled and composted, it has shown favourable properties for use where incineration is the preferred waste disposal method.