Designing an agricultural waste collection and transport network based on robust optimization

Agricultural waste, a widely available resource, has long been plagued by issues of dispersion and inefficient collection. Its improper handling poses serious threats to human health, ecological environment, and economic development. Waste collection and recycling are among the effective measures currently being implemented in many regions to promote sustainable and green development. Waste management is a complex planning issue in an uncertain environment. Designing a more comprehensive and practical agricultural waste collection and transport (AWCT) network is crucial for effective agricultural waste management. This location–allocation–routing problem (LARP) aims to optimize the locations of collection centers (CCs) and processing centers (PCs), effectively allocate waste collected demands, and determine the optimal vehicle routes. This paper focuses on designing a robust AWCT network which can deal with the challenge of uncertainty due to incomplete distribution information. Firstly, two ambiguity sets are proposed to characterize the amount of agricultural waste collected and the operating cost of CC under partial distribution information. Then a distributionally robust optimization (DRO) model is proposed and transformed into a computable mixed-integer linear programming (MILP) form equivalently. Furthermore, a Benders decomposition (BD) algorithm is developed for solving the MILP model. Finally, this method is applied to a case in Shenyang, Liaoning Province, China, to demonstrate the effectiveness of the proposed model and algorithm. The main experimental results show that: (1) The network designed by the proposed model can withstand the influence of uncertainty in the amount of agricultural waste collected and the operating cost of CC at a relatively small robustness price; (2) Managers can adjust the parameters according to their own preferences to achieve a balance between total cost and robustness. The proposed AWCT network design model has certain application prospects. It can provide practical decision-making support for formulating targeted policies and strategies, so as to promote sustainable development and resource utilization, and offer a comprehensive framework for agricultural waste management practices.