PET bottle recycling
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Usage of PET
PET is used as a raw material for making packaging materials such as bottles and containers for packaging a wide range of food products and other consumer goods. Examples include soft drinks, alcoholic beverages, detergents, cosmetics, pharmaceutical products and edible oils. PET is one of the most common consumer plastics used. Polyethylene terephthalate also can be used as main material in making paper.
The empty PET packaging is discarded by the consumer after use and becomes PET waste. In the recycling industry, this is referred to as "post-consumer PET." Many local governments and waste collection agencies have started to collect post-consumer PET separately from other household waste. Besides that there is container deposit legislation in some countries which also applies to PET bottles.
When the PET bottle is returned to an authorized redemption center, or to the original seller in some jurisdictions, the deposit is partly or fully refunded to the redeemer. In both cases the collected post-consumer PET is taken to recycling centres known as materials recovery facilities (MRF) where it is sorted and separated from other materials such as metal, objects made out of other rigid plastics such as PVC, HDPE, polypropylene, flexible plastics such as those used for bags (generally low density polyethylene), drink cartons, glass, and anything else which is not made out of PET.
Post-consumer PET is often sorted into different colour fractions: transparent or uncoloured PET, blue and green coloured PET, and the remainder into a mixed colours fraction. The emergence of new colours (such as amber for plastic beer bottles) further complicates the sorting process for the recycling industry.
Processing for sale
The sorted post-consumer PET waste is crushed, pressed into bales and offered for sale to recycling companies. Colourless/light blue post-consumer PET attracts higher sales prices than the darker blue and green fractions. The mixed color fraction is the least valuable.
The further treatment process includes crushing, washing, separating and drying. Recycling companies further treat the post-consumer PET by shredding the material into small fragments. These fragments still contain residues of the original content, shredded paper labels and plastic caps. These are removed by different processes, resulting in pure PET fragments, or "PET flakes". PET flakes are used as the raw material for a range of products that would otherwise be made of polyester. Examples include polyester fibres (a base material for the production of clothing, pillows, carpets, etc.), polyester sheets, strapping, or back into PET bottles.
Melt filtration is typically used to remove contaminants from polymer melts during the extrusion process. There is a mechanical separation of the contaminants within a machine called a ‘screen changer’ a typical system will consist of a steel housing with the filtration media contained in moveable pistons or slide plates that enable the processor to remove the screens from the extruder flow without stopping production. The contaminants are usually collected on woven wire screens which are supported on a stainless steel plate called a ‘breaker plate’ a strong circular piece of steel drilled with large holes to allow the flow of the polymer melt. For the recycling of polyester it is typical to integrate a screen changer into the extrusion line. This can be in a pelletizing, sheet extrusion or strapping tape extrusion line.
Worldwide, approximately 7.5 million tons of PET were collected in 2011. This gave 5.9 million tons of flake. In 2009 3.4 million tons were used to produce fibre, 500,000 tons to produce bottles, 500,000 tons to produce APET sheet for thermoforming, 200,000 tons to produce strapping tape and 100,000 tons for miscellaneous applications. (Source: PCI, www.pcipetpackaging.co.uk )
Petcore, the European trade association that fosters the collection and recycling of PET, reported that in Europe alone, 1.6 million tonnes of PET bottles were collected in 2011 - more than 51% of all bottles. After exported bales were taken into account, 1.12 million tons of PET flake were produced. 440,000 tons were used to produce fibres, 283,000 tons to produce more bottles, 278,000 tons to produce APET sheets, 102,000 tons for strapping tape and 18,000 tons for miscellaneous applications. (Source: PCI for Petcore and EuPR)
Re-use of PET bottles
PET bottles are also recycled as-is (re-used) for various purposes, including for use in school projects, and for use in solar water disinfection in developing nations, in which empty PET bottles are filled with water and left in the sun to allow disinfection by ultraviolet radiation. PET is useful for this purpose because most other materials (including glass) that are transparent to visible light are opaque to ultraviolet radiation.
- Clark Howard, Brian. "Recycling Symbols on Plastics - What Do Recycling Codes on Plastics Mean". The Daily Green (Good Housekeeping). Retrieved May 7, 2012.
- Teijin Group. "Teijin Develops Eco-friendly Wet-strong Printing Paper Made 100% with Recycled Polyester Derived from Used PET Bottles". Teijin Group. Retrieved March 12, 2013.
- "Plastic Packaging Resins". American Chemistry Council.
- Melt Filtration Options and Alternatives
- http://www.bafu.admin.ch/dokumentation/medieninformation/00962/index.html?lang=fr&msg-id=50084 (page visited on 4 November 2013).
- (French) EcoARK