A variable neighborhood search based matheuristic for a waste cooking oil collection network design problem

Households produce large amounts of waste cooking oil (WCO), which should be disposed properly to avoid its negative impacts on the environment. Using WCO as raw material in biodiesel production is an effective disposal method. In this study, we focus on designing an efficient WCO collection network, in which households deposit their WCO into the bins to be placed at several collection centers (CCs), which are then regularly collected by capacitated vehicles. We study the problem of determining (i) the number and location of the CCs, (ii) the assignment of households to the CCs, respecting a certain coverage distance threshold, (iii) the number of bins to place at each CC, and (iv) the vehicle routes navigating between the biodiesel facility and CCs to minimize the sum of fixed cost of opening CCs and placing bins at each CC and routing cost. To solve the proposed location-routing problem, we develop a novel matheuristic based on Variable Neighborhood Search, which incorporates an integer programming model to determine the bin allocation and assignment decisions. We evaluate the solution performance of different variants of the proposed algorithm by performing an extensive computational study on a set of hypothetical and case instances. The results show that the proposed matheuristic provides superior solutions with respect to benchmark algorithms.