Canadian Plastics

New Strides In Recycling Natural Plastic Bottles

Plastic bottles made from bioresins are no longer new. Nor, however, are concerns that natural plastic bottles are prohibitively difficult to sort from standard polymer bottles during recycling procedures.

May 1, 2009   By Mark Stephen, Managing Editor



Plastic bottles made from bioresins are no longer new. Nor, however, are concerns that natural plastic bottles are prohibitively difficult to sort from standard polymer bottles during recycling procedures.

Biopolymer supplier NatureWorks LLC now suggests this is a non-issue.

Following an extensive analysis of current technology, NatureWorks has concluded that automated systems being used today in the recycling industry are capable of sorting natural plastic bottles from other plastic bottles with an accuracy approaching 100 per cent – and that, therefore, there is no technological barrier to recycling bottles made from plants instead of oil.

“To become more sustainable, the packaging industry must lower the overall waste, energy consumed, and greenhouse gas emitted from the use of plastics, metals, and fibres,” said Steve Davies, NatureWorks’ director of communications and public affairs. “Demonstrating that natural plastic bottles can be brought seamlessly into the recycling steam through the use of automated sorting equipment available today is a major finding and another step towards greater sustainability.”

SURVEY SAYS…

During the past two years, NatureWorks has surveyed equipment manufacturers that have systems with the potential to sort biopolymers from such other plastics as PET, HDPE, PVC, and PS. These sorting systems are usually based on one or more of the following technologies: infrared, ultraviolet, x-ray, colour identification, and laser. NatureWorks has identified a dozen companies offering systems than can potentially sort bioresins and has worked closely with three to ascertain actual sorting accuracies.

Titech, an automated waste sorting manufacturer based in Norway, demonstrated the ability of its near-infrared sorting systems to eject concentrated amounts of NatureWorks Ingeo brand polylactic acid (PLA) plastic bottles in a PET sorting operation. “Sorting efficiency in a single pass was found to be a minimum of 97.5 per cent accurate, a result that is consistent with sorting efficiencies for other materials the equipment ejects as contaminants or passes through as desired streams,” Davies said. German process analysis company Unisensor showed its laser technology was fully capable of sorting Ingeo flakes from desired PET flakes at efficiencies of 96 to 99 per cent, which is consistent with other plastics considered contaminants in the PET flake stream. And MSS, a Nashville, Tenn.-based supplier of automated sorting systems, tested Ingeo natural plastic in its Aladdin near-infrared system. According to Davies, the test confirmed that Ingeo emits a unique polymeric signature; that Ingeo comes up as “other plastics” in a system specifically designed to identify PET, PE, and other plastics; and that the “signature” of Ingeo means that the equipment is programmable to identify Ingeo and sort with high accuracy.

Bolstering these assessments, WRAP, a not-for-profit waste reduction company based in the U.K., conducted an assessment of its own. Published in June 2008, Domestic Mixed Plastics Packaging Waste Options, WRAP concluded that, “NIR (near-infrared) systems can effectively remove PLA bioplastic and carton board from a mixed packaging stream.”

“Accurate sorting is at the heart of making recycling an economically viable business because the recycling operation must be able to separate materials into pure streams – aluminum separated from steel or PET and HDPE plastics from other polymers,” Davies said. “Based on our own work and the analysis of WRAP, we know now that automated systems on the market today can sort natural plastics within industry accepted norms.”

NatureWorks LLC (Minnetonka, Minn.); www.natureworksllc.com; 1-800-664-6436


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