Risk Assessment and Optimization for Routing Hazardous Waste Collection
|關鍵字:||有害廢棄物;路徑優選;清運風險;指標;模式;永續環境系統分析;hazardous waste;routing;risk assessment;index;optimization model;sustainable environmental systems analysis|
Since hazardous wastes (HWs) are harmful, minimizing transportation risk is essential for HW collection routing, especially for highly populated areas with unevenly distributed treatment sites. This study is thus initiated to establish risk-based tools for routing HW collection. First, this study analyzes the risks associated with HW collection based on hazardous material (HazMat) potency, transportation risk, population exposure, and cost factors. The HazMat potency is evaluated based on the physical and chemical properties of HWs and their shipping weights. The transportation risk is estimated by the accidental probabilities of the roads passed in a collection path. The population exposed is counted by the affected areas multiplied by the associated population density. The cost factor is primarily determined by the transportation distance. Two optimization tools for routing HW collection are established, including a computer program implementing the shortest path algorithm and a mathematical programming model for selecting routes based on previously described factors with assigned weights. Three case studies for the HWs generated from manufacturing processes were implemented to elucidate the applications of the tools for routing HWs collection. According to the results, the path selected by minimizing distance likely overlooks the risks. The paths selected by several weight sets can avoid passing through high-risk roads to reduce the risks of HW collection. The paths selected based on the hazardous index are also better than the shortest path. For instance, the path selected for the southern case, while compared with the shortest one, reduces the transportation risk from 0.407% to 0.122%, the population exposure from 5,012 to 3,146, and the transportation risk determined by the P3 method from 2,099 to 439. The path selected based on the hazardous index reduces the index value from 3.22*10^3 to 1.71*10^4, only one-fifth of that for the shortest path.