Carbon Footprint of Mechanical Recycling of Post-Industrial Plastic Waste: Study of ABS, PA66GF30, PC and POM Regrinds

In view of the increasing amount of plastic waste due to a yearly rise in production volume, mechanical recycling of post-industrial waste offers a way to use the scarce resources on earth more efficiently in addition to reducing the global warming potential in the production of raw materials. Therefore, this study addresses the calculation of the product carbon footprint for sorted industrial waste according to the specifications of ISO 14067. The plastics acrylonitrile–butadiene–styrene copolymer (ABS), polyamide 6.6 with 30% glass fiber (PA66GF30), polycarbonate (PC) and polyoxymethylene (POM) were balanced in Umberto LCA+ using the Ecoinvent v3.8 and GaBi SP40 2020 databases and primary data collection from the recycling company Occhipinti. A cut-off approach was applied as an allocation method for evaluating the industrial waste so that the plastic for grinding was imported without burdens from the previous product system. The results show that for all plastics under study, one of the main drivers of the carbon footprint is plastic dust from the grinding process. This insight was used in sensitivity analyses to optimize the modelled processes for a more sustainable production. Improvement potentials were identified by using solar power and disposing of the plastic dust separately according to the type of plastic.