The Location-routing Problem Of Hazardous Waste Recycling Considering The Environmental Risk

Hazardous waste is harmful to the environment and people when it possesses any one of the following characteristics:corrosiveness, toxicity, ignitability, reactivity or infectivity. Owing to the decision-making error or poor management, hazardous waste leak accidents are happened frequenly in recent years, which has led to the serious environmental pollution and ecological damage. In wake of these unpleasant incidents, the environmental risk management of hazardous wastes recycling has become a popular concern.The efficient environmental risk management cosists of the risk assessment and avoidance, in which, the former provides a method to assess unpleasant impacts and the latter provides a way to reduce threats. Hazardous waste poses threats to the environemt during the whole procecedure of recycling, and on the key node and main edge in the transportation network. To carry out a proper risk assessment, the characteristics of environment should be considered, and every step in the recycling system should be involved. Furthermore, both the facility location and vehicle-routing should be optimized simultaneously to avoide potential environmental risks. However, hardly any work in the literature can be found in the environmental risk management of hazardous wastes recycling. Thus, using the theory and method related to the environment engineering, transporation, logistics, et.al, the location-routing problem of hazardous waste recycling considering environmental risks is studied in this dissertation. Aiming to improve hazardous waste logistics and to help the related decision-making, the main content of this dissertation includes:In Chapter 1, we firsly decided to pay more attention on the environmental risk management to meet the urgent requirements from the society. Then, we provided a comprrhensive review of the state of the art on the generic hazardous waste location-routing problem, hazardous transportation risk assessment, environmental capacity, fugacity model, diffusion model and solution proceduce of location-routing problem, and position our work in this context in terms of its contribution.In Chapter 2, we studied the environmental risk assessment for the hazardous wastes recycling. In which, we firsly decided the potential risk sources, risk receptors, and assessment guidelines. In second, based on the environmental capacity, fugacity model, box model and Guassion Plume Model, we defined different environmental risks and then formulated the corresponding assessment models, which have been proved to be able to assess the degree and area of the effects on environment.In Chapter 3, considering the environmental capacity, we studied the location-routing problem of separated hazardous waste recycling system. Based on the designed separated recycling system, we defined the vechile-routing problem as the O-D pairs’optimization and the corresponding waste amount allocation. Then, a location-routing model with the minimizations of total environmental risk, social risk and cost was thereby formulated. Also, the solving steps were designed and a test was provided to prove the workabilities.The location-routing problem of separated hazardous wastes recycling under multiple environmental media was discussed in Chapter 4, where we considered the limitation of real-life transportation network and the waste flow direction in the recycling system. Accordingly, we defined the sub-optimizaiton issue-vehicle-routing prolem-and then formulated a location-routing model with two objectives of miniming total environmental risk and cost through the network flow theory. To solve the small and middle scale problem, a solution procedure was also provided. At last, the effectiveness of the model and algorithm were demonstrated.Considering environmental risks, we studied the location-routing problem of integrated hazardous wastes recycling in Chapter 5, where the distribution of hazardous materials in the atomosphere was especially considered to be equilibrium. At first, we classified the vehile routes in the recycling system into open and closed ones. According to the two-commodity flow formulation, these vehicle routes were re-defined based on an extended network. Secondly, we defined the location-routing problem as a joint optimization of simple facility location, complex vehicle-routing, and the number of vechile needed. Later, we constructed a model with two objectives-minimizing total environmental risk and cost-subjected to the facility and vehicle capacity constraints. To solve the real problem and tests, we used a designed algorithm by adopting the fuzzy technique.In Chapter 6, we discussed the location-routing-capacity problem of integrated hazardous waste recycling under the consideration of environmental risks, where the recycling system was more complicated, and the distribution of hazardous materials was not equilibrium. The vehicle routes were firstly named as collection and transit routes separately. Using two-commodity flow formulation to extend the original network, we defined the location-routing-capacity problem as the joint optimization of facility location and capacity-acquisition, vechile-routing, and number of colletion vechile needed. Under the limitations of facility and vechile capacity, we formulated the mathematical model. Emphersizing the decision-maker’s perfrence, we also proposed a solution procedure based on the weighted goal programming. Finally, the applications of a case study and tests were provided to demonstrate the workabilities.At last, we concluded the main work of this dissertation, and pointed out the innovation. The perspective for the further research was also invlvoed in the conclusion.