Latent Recycling Potential of Multilayer Films in Austrian Waste Management

Abstract

This work presents a hand sorting trial of Austrian plastic packaging, which showed that according to an extrapolation of the 170,000 t separately collected waste collected in Austria, 30 wt% are flexible 2D plastic packaging. Further, the applications for these materials have been catalogued. The composition of these films was evaluated via Fourier-Transformed Infrared Spectroscopy, which showed that 31% of all films were made of polyethene, 39% of polypropylene, 11% of polyethene–polyethene terephthalate composite, and 8% of a polyethene–polypropylene composite, further resulting in the calculation that of all flexible packaging, 20 wt% are multilayer films. These findings were used to calculate the latent potential for raising the current recycling quota of 25.7% to the mandated rate of 55% in 2030. To this end, scenarios depicting different approaches to sorting and recycling small films were evaluated. It was calculated that through improving the sorting of films the recycling rate could be increased to 35.5%. This approach allows for the recycling of monolayer films by avoiding contamination with foreign materials introduced by multilayer films that impede the recyclates’ mechanical properties. The evaluation showed that sorting multilayer films of this fraction could raise the recycling quota further to 38.9%.

Evaluation of Improvements in the Separation of Monolayer and Multilayer Films via Measurements in Transflection and Application of Machine Learning Approaches

“…Through this process, the variability of the spectra is decreased. This variability is defined as the absolute difference between pixels of the same specimen [ 2 ].…”

“…Currently, around 300,000 t of plastic waste are annually produced in Austria, of which 32% are recycled mechanically [ 1 ]. Small films with an area below 1.5 m 2 account for 69,000 t, of which 10,260 t, or 14%, are multilayer films with at least two polymers [ 2 ]. These films are separated during the beneficiation of the waste and are almost exclusively used as alternative fuel sources, incinerated or downcycled into low-value products [ 3 ].…”

“…These films are separated during the beneficiation of the waste and are almost exclusively used as alternative fuel sources, incinerated or downcycled into low-value products [ 3 ]. The substantial potential is latent in the recycling of packaging films since neither co-incineration nor other thermal recovery adds to the recycling quota [ 2 ]. According to the amended EU Waste Framework Directive, municipal solid waste recycling must reach 60% by 2030 [ 4 ].…”

“…Preliminary studies have shown the possibility of separating monolayer from multilayer materials on a laboratory scale using a NIR-active background in an experimental setup [ 7 ]. Further examinations of these findings on an industrial scale NIR Sorter have proven to increase the spectral quality of flexible packaging films by implementing a metal reflector to the sorting geometry [ 2 ]. Implementing a NIR inactive metal sheet as a reflector enabled the sorter to measure in transflectance rather than the usual reflectance mode [ 2 ].…”

“…Further examinations of these findings on an industrial scale NIR Sorter have proven to increase the spectral quality of flexible packaging films by implementing a metal reflector to the sorting geometry [ 2 ]. Implementing a NIR inactive metal sheet as a reflector enabled the sorter to measure in transflectance rather than the usual reflectance mode [ 2 ].…”