Scaling up dissolution-based recycling to eliminate brominated flame retardants from WEEE plastics

The significant challenges of recycling plastics from electrical and electronic equipment waste (WEEE) comprise the mixture of different plastics and their content of brominated flame retardant (BFR). Current recycling techniques are insufficient in removing BFRs, leading to high rejects and incineration of valuable resources. In this study, it is shown that de-pollution by a dissolution-based recycling technique (DBR) is feasible with presorted flame-retarded (FR) acrylonitrile butadiene styrene (ABS-FR) and polystyrene (PS-FR) fractions from WEEE. This was demonstrated at a technical scale of five kg/d with shredded samples, originating from different European sources, characterized by a PS share of > 95 % and an ABS share of > 70 %, as well as bromine concentrations of 12,000 ppm and 33,000 ppm, respectively. Besides novel brominated flame retardants (NBFRs), tetrabromobisphenol A (TBBPA) and decabromodiphenyl ether (decaBDE) above legal thresholds have been detected. After successive extraction by dissolution-based recycling, restricted BFRs have been effectively eliminated to < 500 ppm, ensuring their legal compliance. This achievement underscores the regulatory compliance of the DBR process. The DBR process can be part of a cascade for the treatment of WEEE plastics that includes both spectroscopic pre-sorting and chemical recycling of the side streams. With the interconnection of existing techniques, a far-reaching circulation of EEE plastics is possible.