Wet-mechanical processing of a plastic-rich two-dimensional-fraction from mixed wastes for chemical recycling

The recycling of source separated polyolefins (POs) (e.g., light weight packaging waste) is already state of the art. Therefore, further plastic materials contained in mixed wastes have become more important due to increasing legal pressure. Mixed commercial and municipal solid wastes contain large quantities of POs. These mixed wastes would usually be treated in waste incinerators or processed to refuse-derived fuel for cement plants. Large-scale experiments were conducted to assess the potential of such POs from these waste streams for recycling processes. The potential and applicability of a dry-mechanical and subsequently wet-mechanical (Wet-mechanical) processing with the aim of generating a PO concentrate for chemical recycling purposes was assessed. These investigations’ focus was put on the centrifugal force separator technology as the core element of Wet-mechanical processing. In addition to the input material, all output materials and process water streams were chemically and physically characterized to estimate potential treatment or recycling paths. Results demonstrate that a two-stage purification is necessary to produce POs with sufficient purity out of both wastes. Chlorine and heavy metal levels are simultaneously reduced. The increased quantity of impurities only slightly changes the density of the process waters. Process water analyses show that wastewater treatment is necessary before discharge into a receiving water or sewage treatment plant. The sediment does not fulfil any hazard-relevant properties, and different thermal treatment options are possible.