Collaborative Optimization of Hazardous Waste Mixed Storage and Transportation under Uncertain Demands

To reduce the total risk and cost related to the hazardous wastes mixed storage and transportation, a multi-objective optimization under uncertain demands is proposed, which aims to simultaneously decide facility location, inventory control and route design. Considering the risk derived from mixed storage, an environmental impact disutility function of the treatment station is formulated by introducing toxicity coefficient and odor factor. The resident disutility effect of transfer stations is considered to develop the corresponding risk assessment model. Considering the uncertain demand of hazardous waste inventory and transportation, a computation method of total generation amount is formulated according to the distribution function, and computing the standard line of facility inventory. Minimizing the total risk and cost, a location and transportation model for the hazardous wastes mixed storage and transportation is developed. Based on the improved NSGA-II algorithm, the solution procedure is designed according to the complexity and characteristics of the proposed model. Finally, several tests are provided to demonstrate the workability of the proposed model and algorithm. In which, the computational results show that, the new model and algorithm can provide multiple efficient plans. Comparing to the traditional risk model, the integrated assessment can provide a more economical plan of with great performance in risk equity, which achieving the cooperative guarantee of personnel safety and environmental protection. Comparing to general multi-objective optimization methods, the improved algorithm can shorten the computational time by at least 38.79%, and provide optimal plan within 1700 seconds as well as keep stable performance in solving the problems of different scales