A hierarchical optimisation model for WEEE circular plant operations: evidence from a case study in copier recovery

Waste Electrical and Electronic Equipment (WEEE) presents environmental challenges and economic opportunities. Established by manufacturers, circular plants handle the physical recovery of end-of-life WEEE. Prior research has focused on WEEE component-level recovery decisions through complete or partial disassembly planning, which incur unnecessary costs or overlook the non-disassembled residue. This paper develops a hierarchical optimisation model that applies recovery or disposition options across finished products, sub-assemblies, components, and basic materials to address the drawbacks of complete and partial disassembly, aiming to enhance the profitability of circular plants under external dynamics. Validated by a copier recovery case study, although the profit projection in our hierarchical recovery mode still demonstrates a loss, the loss is reduced by 58%. The recovery weight percentage increases by 1.5% compared to the complete disassembly recovery mode, even in the worst scenario. This paper enriches the literature on WEEE recovery and disassembly planning from a circular plant perspective.