Optimizing municipal solid waste collection vehicle routing with a priority on infectious waste in a mountainous city landscape context

The growth of the economy, urban sprawl, and population expansion precipitate a substantial increase in solid waste generation, particularly in vital regions like the capital area and economically significant cities, including renowned tourist destinations. Furthermore, the protracted spread of the COVID-19 virus has led to a notable increase in the quantity of infectious waste. In this regard, the safe and effective management of municipal solid waste (MSW) collection and transportation emerges as a major concern in MSW management. This paper aims to determine routes for waste collection, both infectious and noninfectious, from waste collection points to diverse waste disposal sites in the mountainous Khao Kho district of Phetchabun province, located in northern Thailand, with the objective of minimizing total fuel consumption and service time. Fuel consumption is contingent upon both the distance traveled and the prevailing condition of the road. The road condition exerts an influence on the vehicle's speed, thereby directly impacting fuel efficiency. In the context of service time, priority is assigned to collection points with substantial quantities of infectious waste, given the imperative to promptly dispose of such waste to mitigate the risk of transmission. In this paper, a mixed-integer programming model and three modified differential evolution (MDE) algorithms were developed to solve the problem. The computational results reveal that the MDE outperformed the traditional DE and is effective for the MSW transportation management system.