A Critical Review of Circularity in the Recycling of Waste Electrical and Electronic Equipment Plastics in the Presence of Flame Retardants

Reintegrating plastic waste from waste electrical and electronic equipment (WEEE) into production cycles remains challenging because flame retardants (FRs) can restrict its reuse. FRs are essential for fire safety in electrical and electronic equipment (EEE), but regulations have restricted the use of several halogenated FRs. This review evaluates recycling technologies for WEEE plastics containing FRs in the context of the circular economy, with particular attention to changes in regulatory status over time. Mechanical recycling can return these plastics to the same production cycle while retaining their properties for up to four reprocessing cycles. For plastics containing restricted FRs or concentrations exceeding regulatory limits, pyrolysis offers an alternative recycling route in which FR extraction can be incorporated into the process, allowing the material to re-enter the production cycle. Life cycle assessment (LCA), however, indicates that pyrolysis of plastics containing halogenated FRs carries an environmental burden. Achieving circularity for WEEE plastics therefore remains challenging because research has yet to address environmental, technical, regulatory, and social considerations together, particularly as regulatory requirements change over time.