Plastic recycling has come a long way over the last few decades.  Expanded collection efforts, increased demand for reclaimed material, and technology advances have combined to allow greater recovery of materials. While technology innovation spans a wide range of processes—from shredding through compounding and extrusion—one category that is receiving more attention and credit for growing recovery opportunities is automated sorting technology.

Basically, automated sorting technology processes information with a computer and sorts materials with pneumatic air knives. The technology comes in a few varieties, including:

•  Vision technology: This is essentially a camera that can sort colors and shapes;
•  Infrared technology: This is used to differentiate between resin types by their IR absorption spectra. This category of optical sorters includes near-infrared (NIR), mid-infrared (MIR) and Raman laser spectroscopy;
•  X-ray technology (XRF and XRD):  This allows users to “see through” the plastics at the elemental level and detect heavy elements such as chlorine and bromine, differentiating PVC from look-alike PET, and detecting brominated flame retardants that cannot be returned to manufacturing in some markets.

These technologies can be capable of sorting large volumes of whole containers, large plastic pieces, or small flakes in mass quantity. NIR Sorting Machine and XRF technologies can also be miniaturized into handheld units that allow for individual identification of a piece or part.

NIR Sorter Machine is both faster and more accurate than manual sorters. Automatic sorters interface NIR sensing with air nozzles to sort plastic items of various resin compositions, for example separating PET bottles from HDPE bottles. To obtain the highest material value, the equipment must sort the items effectively and accurately.  Otherwise, the article is either directed to the waste stream or becomes a contaminant in another recyclable stream where it is likely to not be recycled.It is also common for some plastic reclaimers touse NIR equipment near the end of the processing line for final contaminant removal as well.

With the help of sorting methods based on NIR spectroscopy, efficient plastic recycling is doable at home, collection points and sorting facilities. NIR technologies can help convert plastic waste into a renewable resource and reduce waste and pollution. This has already been done with textiles – we’re excited to see what the future will bring for plastics.

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