Profit-driven planning and analysis of a WEEE recycling facility with a multi-period MILP model

2023

Electronic waste is one of the fastest-growing waste streams in the world. The challenges

associated with the recycling of Waste Electrical and Electronic Equipment (WEEE) represent

both threats, as the improper disposal of this waste can harm the environment and human health,

and opportunities, as this category of waste contains valuable and rare resources that can be

recovered and repurposed, contributing to the circular economy. The EU is leading the way in

improving the collection and treatment of WEEE, but this has not been sufficient to meet the

targets set in its WEEE directive. Therefore, additional efforts must be made to ensure the costeffective

and environmentally sound recycling of WEEE, both in the public and private sectors.

In this thesis, we propose a multi-period MILP model for the planning of a WEEE recycling

facility in Belgium and conduct various analyses to provide insights on what elements are the

most crucial to the profitability of such a facility. The originality of our approach lies in the

multi-period aspect of the model, and the addition of a limited amount of labour to be allocated

to various labour-intensive tasks of WEEE recycling. Our main findings are that labour is the

most critical resource, both in cost and utilization, such that the optimal quantity of WEEE to

process is the one that results in complete utilization of labour, with little to no overtime. As

such, the flexibility of labour, both in possible task allocation and overtime capabilities, is

crucial to the proper functioning of the facility, especially when taking into account possible

deviations from the optimal plan, caused by the heterogeneity of WEEE and other variations

such as the timing of deliveries.