| 摘要: | 地下水污染場址之常見的污染物之一為揮發性有機化合物（Volatile organic compound, VOC），如苯類、三氯乙烯等。這些污染物之特性為密度高且水溶性低，當污染物進入地下水層將累積於不透水層，並且污染範圍逐漸擴大，也造成整治困難。尤其是疏水性之環狀含氯有機物，容易吸附在土壤中並緩慢脫附而形成一長期之污染源，對地下水之水質造成長期之危害。近年來在地下整治技術中，由於考量到能源消耗、整治成本及技術門檻等問題，許多學者專家開始研究利用生態工程（Ecological Engineering）中之水質自然淨化技術來整治土壤及地下水污染場址廢水。其中人工濕地（constructed wetland）是仿效自然濕地的淨化及生態保育的功能，應用自然淨化機制來處理污水，亦即將生態工程技術應用在污水或廢水的管理及處理上的一種自然淨化程序。相較於傳統污水處理技術，人工濕地具有節省能資源、成本廉、無二次污染、操作維護簡便等優點。在表面下流動式濕地系統（SSF）中，溫度為影響有機污染物處理效率之重要因素，為瞭解溫度對在不同介質SSF濕地處理效率之影響，本研究針對SSF濕地系統中之主要污染物：順-1,2-二氯乙烯進行分析。除本研究之數據外，並納入過去一年本濕地系統之數據（陳明華, 2012），時間自100年7月5日至101年8月6日，每座濕地系統共計有28點數據。順-1,2-二氯乙烯進流濃度最高為3.31 mg/L，最低為0.696 mg/L。秋冬季（9月至隔年2月）之濃度普遍較春夏季（3月至8月）高。順-1,2-二氯乙烯在填充天然礫石SSF溼地系統中，出流濃度最高為2.45mg/L，最低為0.185 mg/L。去除效率最高為88.2%，最低為 -2.7%，採樣期間之平均去除效率為51.6%。比較各月份之去除效率，以8月份之平均去除效率最高，達88.2%，11月份之平均去除效率最低，僅27.0%。順-1,2-二氯乙烯在填充廢棄水泥塊SSF溼地系統中，出流濃度最高為1.92 mg/L，最低為0.239mg/L。去除效率最高為89.7%，最低為 -7.5%，採樣期間之平均去除效率為59.9%。比較各月份之去除效率，以8月份之平均去除效率最高，達89.7%，1月份之平均去除效率最低，僅21.6%。順-1,2-二氯乙烯在填充拉西環SSF溼地系統中，出流濃度最高為2.95 mg/L，最低為0.260mg/L。去除效率最高為78.8%，最低為-65.9%，採樣期間之平均去除效率為31.3%。比較各月份之去除效率，以8月份之平均去除效率最高，達78.8%，1月份之平均去除效率最低，僅-15.1%。比較三座人工濕地系統在20℃時之反應速率常數（K20），以填充廢棄水泥塊之SSF濕地系統最高，對順-1,2-二氯乙烯之處理效果為三者最佳，其次為填充天然礫石之SSF濕地系統。填充拉西環之SSF濕地系統在20℃時之反應速率常數僅0.04，為三者最低，對順-1,2-二氯乙烯之去除效率為三者最差。
One of the common contaminants is volatile organic compound, such as benzene, trichlorethylene, etc. The characteristics of these contaminants are high density and low water-solubility. Contaminants will accumulate in impermeable layer after entering groundwater. The expansion of pollution results in the difficulty of remediation. The contaminants, especially for the hydrophobic cyclic chlorinated organics, will be adsorbed to soil, and then desorbed slowly to form a long-term pollution source.Recently, because of the consideration in energy consumption, remediation cost and technical thresholds, lots of studies focus on soil and groundwater redemdiation by ecological engineering. Constructed wetlandsare ecological engineering mechanisms applied in wastewater treatment, which simulate the purification and ecological conservation of natural wetlands. Compared to conventaional wastewater treatment technology, constructed wetlands have several advantages: energy and resource saving, lower cost, no secdondary pollution, convenience of operation and maintenance, etc.In a subsurface flow (SSF) constructed wetland, temperature plays an important role on the removal efficiency of organic pollutants. In order to understand the effect of temperature on different SSF constructed wetlands, the major contaminant, cis-1,2-dichloroethylene, is analyzed in this study. Besides the data obtained from this study, the data from the past year were also included. The duration is from July 5th, 2011 to August 6th, 2012, and 28 points of data were obtained for each SSF constructed wetland.During the period, the highest concentration of cis-1,2-dichloroethylene in influent is 3.31 mg/L, the lowest is 0.696 mg/L. Generally, the concentration of cis-1,2-dichloroethylene is higher in fall and winter (from September to next February) than that in spring and summer (from March to August).In the SSF constructed wetland filled with natural gravels, the highest concentration of effluent is 2.45 mg/L, and the lowest is 0.185 mg/L. The highest removal efficiency is 88.2%, and the lowest is -2.7%. The average removal efficiency is 51.6%. Comparing the removal efficiencies among each month, the highest is in August (88.2%), and the lowest is in November (27.0%).In the SSF constructed wetland filled with recycled concrete debris, the highest concentration of effluent is 1.92 mg/L, and the lowest is 0.239 mg/L. The highest removal efficiency is 89.7%, and the lowest is -7.5%. The average removal efficiency is 59.9%. Comparing the removal efficiencies among each month, the highest is in August (89.7%), and the lowest is in January (21.6%).In the SSF constructed wetland filled with raschig rings, the highest concentration of effluent is 2.95 mg/L, and the lowest is 0.260 mg/L. The highest removal efficiency is 78.8%, and the lowest is -65.9%. The average removal efficiency is 31.3%. Comparing the removal efficiencies among each month, the highest is in August (78.8%), and the lowest is in January (-15.1%).The reaction rate constant at 20℃(k20) of the SSF constructed wetland filled with recycled concrete debris is highest among three wetlands, following by the wetland filled with natural gravels and raschig rings. The higher k20 indicates the better removal efficiency to cis-1,2-dichloroethylene. |
