有害廢棄物清運路徑風險評估與優選

Abstract

有害廢棄物由於具有危害性，加上人口密度高及處理場分配不均，導致增添清運風險，故必須規劃適當之清運路徑以降低風險，唯國內目前尚無適當的工具可供使用，本研究因而建立一套優選有害廢棄物清運路徑之方法。本研究首先分析有害廢棄物清運風險相關因子，分為有害廢棄物物質風險、運輸風險、沿線影響人口及成本。有害廢棄物物質風險因子主要是基於有害廢棄物物化特性及運輸重量評估物質風險指標；運輸風險因子主要考量各路段運輸事故發生機率的計算方式；沿線影響人口因子則是依據有害廢棄物危害影響範圍乘上人口密度估算；而成本因子主要考量運輸距離，建立上述因子評估方法後，接著建立有害廢棄物清運路徑優選工具，分為演算法及規劃模式，演算法採用最短路徑法，並依據各路段清運風險及成本作為權重，進行路徑優選；規劃模式以最小清運風險及成本作為目標式，並利用權重法設定不同權重優選路徑。 本研究所建立的方法適用於國內不同類型有害廢棄物之清運路徑優選，並以種類複雜及產出量最多的製程有害事業廢棄物進行案例研討，並建立北部、西部及南部各一虛擬案例，以示範應用本研究所建立之方法。根據結果發現，若僅考量成本規劃清運路徑，易忽略清運風險，而各案例優選清運方案與最短路徑清運方案比較，優選清運方案可避免行經高風險路段，有效降低清運風險，針對危害性進行分析，危害性指標也明顯優於最短路徑清運方案，如南部案例優選清運方案比較最短路徑清運方案，運輸風險值由0.407%降至0.122%、沿線影響人口數也由5012人降至3146人，依P3法所估算運輸風險值因而由2099降至439，危害性指標R_POP_HP(3.22*10^3)也降為最短路徑(1.71*10^4)清運方案的五分之一倍。

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.