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Separation success means biomaterials don't contaminate recycling streams, says NatureWorks.

The argument against making bottles from biodegradable materials because they might contaminate the recycling waste stream no longer applies according to PLA manufacturer NatureWorks. The company has been running tests on recycling systems and says that automated systems being used today in the recycling industry are capable of sorting bio-sourced plastic bottles from other plastic bottles "with an accuracy approaching 100 per cent".

According to Steve Davies, NatureWorks director of communications and public affairs "Demonstrating that natural plastic bottles can be brought seamlessly into the recycling stream through the use of automated sorting equipment available today is a major finding and another step towards greater sustainability."

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

* Titech, whose near-infrared sorting systems were able to eject concentrated amounts of NatureWorks Ingeo PLA in a PET sorting operation. Sorting efficiency in a single pass was found to be a minimum of 97.5 per cent accurate, consistent with sorting efficiencies for other materials the equipment ejects as contaminants or passes through as desired streams.

* Unisensor, whose laser technology was capable of sorting Ingeo flakes from desired PET flakes at efficiencies of 96 to 99 per cent consistent with other plastics considered contaminants in the PET flake stream.

* MSS, which tested Ingeo in its Aladdin near-infrared system and confirmed that Ingeo emits a unique polymeric signature. The test demonstrated that Ingeo comes up as "other plastics" in a system specifically designed to identify PET, PE, and other plastics. The unique signature of Ingeo means that the equipment is programmable to identify Ingeo and sort with high accuracy.

NatureWorks says that its own trials have been echoed by WRAP in Britain, which in June last year published Domestic Mixed Plastics Packaging Waste Options, in which it concluded that, "NIR (near-infrared) systems can effectively remove PLA bioplastic and carton board from a mixed packaging stream."

PLA is not just seen as a successfully separable contaminant. In 2007 the Institute for Energy and Environmental Research (IEER), in Heidelberg, Germany, found that the recycling of post-consumer Ingeo into new water bottles will offer environmental, energy, and package performance advantages compared to recycling PET back into bottles. The process used hydrolysis to break the post consumer bioresin down into lactic acid, which could then be reformulated back into virgin polymer. Subsequently NatureWorks performed hydrolysis tests on Naturally Iowa Milk Ingeo bottles. The company found that impurities such as caps and label material can be filtered down to levels that allow recycling back to bottle-grade polymer. NatureWorks is now preparing a large scale hydrolysis pilot project involving post-consumer material in bottle-to-bottle recycling.
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Title Annotation:reclamation & recycling
Comment:Separation success means biomaterials don't contaminate recycling streams, says NatureWorks.(reclamation & recycling)
Publication:British Plastics & Rubber
Date:Apr 1, 2009
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