By Jan H. Schut
Postconsumer mixed plastic film is at the bottom of the MRF (material recovery facility) waste chain. Both in Europe and the U.S. mixed plastic film, known as “2D 1-7” (two dimensional film, polymers 1 through 7) is a contaminant that lowers the value of recycled paper. So MRFs typically remove plastic film from the paper stream, either by hand or automatically. Automatic removal of film from paper by near infrared vision sorting isn’t new. It has been done commercially at MRFs in Europe and the U.S. for at least ten years, notes Jonathan Clarke, country manager for the U.K. division of Tomra Sorting AS in Asker, Norway, which makes TiTech NIR sortation devices (www.titech.com).
Mixed film is only a tiny fraction of “2D” MRF material (3%-6% film vs. 94%-97% mixed paper), so it’s typically landfilled or burned. But that could be changing. Interesting investment is going on now in the first installations of automatic high-speed NIR sorting of plastic film not at MRFs, but at plastic recyclers both in Europe and the U.S. Recyclers are sorting to retain PE film and reject other polymer films. The possibility of upgrading commingled MRF plastic and reusing the PE was extensively studied by the Waste & Resources Action Programme in Oxon, U.K. (www.wrap.org.uk) between June and December, 2012.
The WRAP study (www.wrap.org.uk/content/resources-enable-recycling-household-plastic-films) used “2D” paper and plastic film collected at Casepak, Leicester, U.K. (www.casepak.co.uk), a MRF accepting commingled household recyclables including film. Casepak shipped 146 metric tons of paper and film to BS Environnment, a MRF in Nimes, France, with two NIR sorting devices from Pellenc Selective Technologies, Pertuis, France (www.pellencst.com). The first NIR device removed all plastic film (metalized pouches, nylon, HDPE, LDPE, PP, PS and PVC) from the paper. The second NIR separation retained PE film and removed everything else, i.e., remaining paper and non-PE plastic film. BS Environnment sent 2.67 metric tons of sorted PE film to a plastic film recycler in France, Regefilms Sud Ouest in Abidos, which has since gone out of business.
FIRST AUTOSORTING OF PLASTIC FILM BY POLYMER
Regefilms was chosen for the WRAP test because it had two washing and recycling lines for film, one from Herbold Meckesheim GmbH, Meckesheim, Germany (www.herbold.com) and one from Sorema division of Previero (www.sorema.it), and automatic NIR film sortation from PellencST already in place. Regefilms sourced film from household waste and agricultural film and sold pelletized material to the Barbier Group, a packaging company in Ste. Segolene, France (www.barbiergroup.com), which used the material at up to 80% in trash bags.
Regefilms shredded the baled PE film from the WRAP test, automatically removed remaining paper and unwanted polymer films, then washed and pelletized the PE film, sending 1.79 metric tons of pelletized WRAP material to CeDo Ltd., Telford, U.K. (www.cedo.com), a maker of film and packaging. Pellets sent to CeDo had MFI (g/10 min.) of 0.55-0.58 and density of 0.923-0.926, close to CeDo’s own recycled film of 0.5-0.7 MFI and 0.92-0.94 density. CeDo blended the material into test bags at 40% and 60%.
When Regefilms went into liquidation in June 2013, its recycling machinery and NIR sorters were bought by its major customer, Barbier, and moved to Ste. Segolene, France, where they are expected to start operation again in 2014. PellencST also has four NIR sorting devices at a U.K. film recycling company, which is starting up now, and the first automatic film sorters are on order for the U.S. for a company that makes a recycled-content packing product.
Tomra has TiTech NIR installations for automatic film removal from paper at numerous MRFs in the U.S. and Europe, including SIM’s Recycling Solutions Inc.’s new MRF in Sunset Park, Brooklyn. SIMS’ Brooklyn MRF started up in December 2013 to process recyclables from New York City’s five boroughs. In the U.K. Tomra has at least three MRF installations, which also make a second separation of PE film from commingled films. These include an installation at Weir Waste Services Ltd., Oldbury, U.K. (www.weirwaste.co.uk), using TiTech’s latest “Autosort 4” NIR technology. Autosort 4 integrates lighting with scanning and is reportedly cooler and more energy efficient than other NIR systems. Weir separates PE film, bales it, and sells it to film recyclers.
TiTech’s Autosort also reportedly can distinguish between very similar spectrometer wavelengths of HDPE and LDPE. “TiTech units have been doing this for at least six years,”says Tomra’s Clarke. “But only in the last three years has the software improved to allow sufficient accuracy.” It’s impressive that NIR optical film sorting can extract 95% pure PE film from commingled plastic film from MRFs and tell the difference between HDPE and LDPE. But optical sorting still has limitations to overcome. It can’t identify polymers in black film, so black bags have to be removed some other way. Nor can it identify multilayer barrier PE films–it only reads the surface layer. Another problem with film sourced from MRFs may be smell. The WRAP study notes that pelletized “trial PCR had distinct odor when compared to CeDo PCR, which could have impact on its salability.” The test suggests that smelly pellets could be blended in small quantity. WRAP has a new study on potential end markets for MRF PE film (even if it is a little smelly), due in 2014.