European Bioplastics pushes for NIR tech in biodegradable plastic recycling

European Bioplastics stresses the need to recycle biodegradable plastics to strengthen circularity. In a position paper, the organization outlines how recycling can serve as an important end-of-life pathway for bioplastics when supported by near-infrared (NIR) sorting technology. 

If not composted or used for marine applications, biodegradables can be collected in plastic collection streams, sorted, and materially recycled without adversely affecting the recycling of other plastic streams.

"To realize a true circular economy, it is imperative to establish high-quality recycling systems that ensure the secondary raw materials produced can successfully replace virgin materials. Achieving this requires maintaining a clean and high-quality material stream, making efficient sorting a crucial first step towards high-quality recycling," the paper states.

European Bioplastics presents evidence that biodegradable plastic polymers do not affect the recycling or recyclability of other plastic waste. 

“Efficient sorting of all plastics can be performed with existing NIR equipment at sorting and recycling facilities as long as the respective spectra libraries for those plastics are used,” says European Bioplastics.

“Poor sorting leads to inefficient recycling, independent of the recycling stream and process. To obtain high-quality recycling outputs, constant improvement in sorting efficiency is needed.”

NIR sorting of bioplastics

European Bioplastics highlights that existing sorting technologies, like NIR sorting, are key.

The NIR spectra of PLA and PET shows the differences in peaks (Graph credit: European Bioplastics).“As most biodegradable plastics are mainly polyesters, the NIR-spectra of those polymers (including their blends) are distinctly different from PE, PP, PS, and even PET,” says the organization. 

One of the concerns often raised is that biodegradable polylactic acid (PLA) could contaminate PET streams, according to European Bioplastics. “However, the NIR spectra for PLA and PET are clearly distinguishable in standard NIR equipment.”

European Bioplastics points to the two successful dynamic sorting tests by TotalEnergies Corbion completed at a Tomra German testing center in August 2022. 

“The first test was with mixed plastic packaging waste, including PLA trays, using the Tomra NIR sorting machine to positively sort PLA out in order to determine if the trays are recognized and sorted correctly.”

“In order to determine whether the PLA trays are falsely sorted to PET, a second test was carried out. In this case, the aim was sorting PET from a mix of packaging waste that included 30 PLA trays.”

The industry association says the tests demonstrated the correct sorting of PLA trays in the appropriate stream, with minor and ordinary mechanical oversorting. 

Sealive optic sorting tests

Antoine Bourely, chief scientific officer and co-founder at the connected optic sorting company Pellenc ST, says the company has been testing the sortation of bioplastics within the European project Sealive.

“All polymers tested have been perfectly separated from fossil-based plastics in the lab, and PLA has been well sorted in a Spanish materials recovery facility (MRF) operated by Urbaser. This sortation did not create any loss of other plastics from that MRF.”

Additionally, lab tests have shown the ability to separate the bioplastics from each other in four main classes: PLA, PHA, PB+, and Cellulose Acetate.

“This opens the door to many end-of-life opportunities for bioplastics, including composting and recycling, and especially so, since most sorting lines in Europe already use a NIR system,” says Bourely.