含氯有機溶劑GCW整治案例分析

Abstract

本研究利用MODFLOW程式模擬地下水流，配合MT3DMS模擬污染物之傳輸，並以高雄台塑仁武廠做為案例分析，其主要受到1,2二氯乙烷及氯乙烯兩種含氯有機溶劑的污染。本研究針對高雄台塑仁武廠，模擬現地污染狀況以及預期現地的GCW配置整治效果，同時經由模擬結果針對現地的GCW配置作改善配置，再比較不同循環水量(54 m3/day、100 m3/day、200 m3/day、300 m3/day)以及調整異向比對於整治的影響，最後再經由多次模擬找出較佳的配置。 研究結果顯示，現地GCW的配置(循環水量為54 m3/day)於氯乙烯廠所形成的循環範圍及捕獲範圍無法整治到1,2二氯乙烷污染團中心，使得整治過程中污染團持續擴大，導致GCW無法完全攔截到，甚至到7700天後濃度依然降不下來(最高濃度為1 mg/L)，氯乙烯的部分因污染團中心濃度相對較低，於整治期間污染團較無明顯擴散，因此整治效果相對較佳。而改善後的配置(循環水量為54 m3/day)由於加入2口GCW針對1,2二氯乙烷污染團中心做整治以及4口GCW作為與現地配置垂直的攔截牆，經過模擬的結果發現約整治7300天，1,2二氯乙烷及氯乙烯濃度均降至管制標準以下，故顯示改善配置的整治效果相較於現地配置有明顯的提升；較佳配置的部分則是在改善配置中額外增設2口GCW於污染團中心且循環水量為300 m3/day，結果顯示約整治3300天，污染濃度均降至管制標準以下。 此外，經研究顯示當循環水量提高時，循環範圍及捕獲範圍也會隨著增加，使得1,2二氯乙烷及氯乙烯的總量下降的越快，且整治時間也越短，但是隨著循環水量的提升捕獲範圍增加的幅度也越小；而異向比的部分則是當異向比越大循環範圍及捕獲範圍越大，反之，異向比越小循環範圍及捕獲範圍越小，但是隨著異向比越大及循環水量的提升，則捕獲範圍增加的幅度也會變小。因此在設計的時候除考量循環水量、循環範圍及捕獲範圍對於整治的影響外，垂直向的水力傳導係數也必須能夠掌握，才能有效的評估整治結果。

This research studied the migration of chlorinated solvent plume in aquifer by simulation with MODFLOW and MT3DMS. The DNAPL site Renwu Factory of Formosa Plastics Corporation in Taiwan Kaohsiung was chosen as the site for the case study. Groundwater in the aquifer beneath the Renwu Factory is contaminated with 1,2-dichloroethane and vinyl chloride. The GCW remediation was simulated to study the result on remediation efficiency by modifying GCW configuration. In addition, the circulation rate of the GCW (at 54 m3/day, 100 m3/day, 200 m3/day, 300 m3/day ) and various anisotropy ratio of hydraulic conductivity was also as simulated for comparison. The results show that in-situ configuration(Q=54 m3/day) cannot fully cleanlup the 1,2-dichloroethane plume at vinyl chloride factory because of the circulation cell and the capture zone are not large enough to intercept the plume. The concentration of 1,2-dichloroethane still exceeds regulation limit until 7700 days of remediation. However, the concentration of center of vinyl chloride plume is relatively low,and the plume did not expand significantly such that the remediation efficiency is better than vinyl chloride. The improved configuration (Q=54 m3/day) which add two GCWs to remediation the center of 1,2- dichloroethane plume and four GCWs as the barrier at in-situ configuration . As a result, the 1,2- dichloroethane and vinyl chloride almost disappeared after 7300 days. On the other hand, the improved configuration makes the remediation efficiency increase. Furthermore, the improved configuration which add two GCWs to remediation the center of 1,2- dichloroethane plume and elevated circulation rate (Q=300 m3/day) reduce the remediation time from 7300 days to 3300 days. The result of this research show that, when the circulation rate increases, the size of the capture zone and the circulation cell also increase. Similarly, the increase of anisotropy ratio resulted in a larger capture zone and a circulation cell. But both the circulation rate and anisotropy ratio are too large, it will lead to a smaller increased rate for the capture zone.