Developments in automated sorting technology are making it possible to achieve exceptional purity results in plastics recycling – from coloured and clear types of plastic such as PET and
HDPE, to other polymers like polypropylene, polystyrene and PVC. With the right combination of automated sorting technology, it is possible to achieve previously unfeasible purity levels of over 99.99 per cent.
Recovered end fractions can be used to produce recycled products such as fibre for the textile industry or to make new sheets or bottles. This closed-loop approach, which reduces demand for virgin materials, is working very effectively in a number of European countries such as Austria, Germany, France and Belgium. These countries have not only introduced effective waste legislation, but have invested heavily in their waste infrastructure and, in particular, in the right sorting facilities and technology.
Let’s take a look at some of the more challenging areas of plastics recycling where sensor-based sorting is helping European recycling companies achieve ground-breaking results.
Flake sorting for food-grade material
At TOMRA Sorting Recycling, we have developed the AUTOSORT flake sorter – a world-class plastics recycling solution that is enabling reprocessors to achieve the high purity and quality levels demanded by customers for food grade recycled PET (rPET) flakes.
The unit combines a visible range spectrometer (VIS) to detect colour contaminants and a near infrared (NIR) spectrometer to detect different polymer types such as PET, HDPE, PP, PVC, PA, PS, PLA etc. Flakes as small as 2mm can be identified and sorted, contamination is eliminated and a consistent yield of super-clean recycled PET can be delivered at unparalleled purity levels.
TOMRA is currently involved in a project for French company Regene Atlantique – part of the SUEZ Group. Regene Atlantique operates a PET recycling plant in Bayonne in the south west of France where four AUTOSORT units and the latest AUTOSORT flake technology are installed. Using this combination of technology, Regene Atlantique can achieve the quality levels required by some of the biggest soft drinks companies in the world. Contamination levels are set by these customers of below 10ppm (parts per million) on PVC, below 3ppm on metallic (ferrous and non-ferrous particles) and less than 200ppm on other unwanted material such as other colours or polymers.
Flake sorting is likely to be a major growth area in many European countries in the future as it offers a highly effective final opportunity for recycling companies to improve their material quality and satisfy customers’ requirements. On the back of the success of PET flake sorting, TOMRA is now developing a similar solution for PE and PP flakes.
Black plastics
Black plastics is another area where sensor-based sorting technology is breaking new ground. Many packaging companies favour black plastics for certain items but infrared cameras cannot detect the carbon in black plastics so historically this material has not been recyclable. Now though, studies are looking at adding a pigment or marking to the bottles or trays that would make the material detectable and recoverable using AUTOSORT.
Opaque PET
Throughout Europe, the use of PET continues to grow and PET bottles are widely replacing HDPE bottles. Opaque is used in PET bottles to protect the contents from light and oxygen but this can cause problems when it comes to recycling, as the opaque bottles can easily be confused with HDPE by the human eye. However, the AUTOSORT unit is capable of detecting and recovering all types of opaque PET bottles from transparent colours, making it possible for the first time to recycle this increasingly popular plastic material.
TOMRA
PET trays
Currently, PET trays, which are normally used for meat products, are not sorted out separately or recycled, however the latest sorting technology is capable of detecting this kind of multi-layered PET product. Although the recovered material is still classed as waste, work is underway to determine how this co-polymer can be properly recycled.
Plastic films
A good example of closed loop recycling in practice is the recycling of plastic foils from packaging. Using the latest automated technology, it is now possible to achieve 100 per cent recycled content clear films or high purity PE films which are suitable for extrusion and use in new product manufacturing, completely closing the loop on plastic foils. A major French PE foils manufacturer is already using TOMRA’s technology with great results.
Detecting different types of PE
Sensor-based technology is also capable of detecting different types of PE and one application that is generating a lot of interest is separating food and non-food packaging. TOMRA has developed a pioneering unit that uses an extended wavelength scanner to detect the difference between homo- and co-polymer. This process makes it possible to separate the non-food containers, which would be almost impossible to do manually using visual inspection. It is effectively separating two polymers within one polymer group.
This solution is already in place at Australian packaging and resource recovery company, Visy Industries Australia Pty. The company has installed a bottle-to-bottle recycling facility in New South Wales, Australia, for the food-grade production of PET and HDPE regranulate. The plant is the first of its kind in Australia and produces 2,500 – 2,900kg of recycled food-grade PET pellets and up to 1,500kg recycled food-grade HDPE pellets per hour. It operates using a PET recycling extruder and HDPE decontamination equipment from Starlinger, a Sorema washing line, and sorting equipment supplied by Stadler Anlagenbau GmbH and TOMRA Sorting Recycling. The input material consists of PET and HDPE bottle waste from kerbside, commercial and industrial waste collection. The recycled PET pellets are used by Visy in its own preform production, while the food grade rHDPE pellets from milk bottles are sold to customers worldwide.
Future innovation
With continued investment in R&D, a commitment to a culture of innovation and close collaboration with plastics manufacturers and recycling companies, TOMRA is continually striving to identify new plastics recycling opportunities.
Words | Frédéric Durand, Plastics Segment Champion at TOMRA Sorting Recycling
