受苯、甲苯與1,2-二氯乙烷污染場址之案例研究

benzene, toluene and 1,2-dichloroethane

游明哲(Ming-Che Yu)

指導教授 ： 張木彬

國立中央大學/工學院/環境工程研究所碩士在職專班/碩士(2007年)

摘要

本研究以受苯、甲苯及1,2-二氯乙烷污染場址為案例，藉由現場土壤及地下水長期採樣分析，探討空氣注入法(Air Sparging, AS)結合土壤蒸氣萃取法(Soil Vapor Extraction, SVE)技術，處理受石油碳氫化合物和氯化碳氫化合物污染場址之可行性、效能及處理機制，並評估AS結合SVE技術之整治成本效益。
研究結果顯示，此系統經過11個月的操作之後，於未飽和層土壤中苯及甲苯之去除率均達100%，另於阻水層上方之含水層土壤中之1,2-二氯乙烷去除率為100%。地下水中苯及甲苯之去除率均達100%，且苯及甲苯之降解速率符合擬一階反應速率模式，其反應速率常數（k）各為0.0576 day-1及0.0586 day-1。此外，地下水中的溶氧量達1mg/L以上，地下水由厭氧環境轉變成好氧狀況，同時微生物總菌落數亦由40CFU/mL增加到1.7×105CFU/mL，大幅增加4250倍，顯示場址生物降解作用存在。另一方面，藉由SVE系統可抽除土壤揮發性有機物(VOCs)，推估瞭解土壤中可能受有機化合物污染物之質量，本研究以本場址共抽取2,282 kg之VOCs。整體而言，本系統中AS系統可增加地下水溶氧，促進現地微生物分解有機污染物，同時具有氣提溶解於水中之VOCs，揮發至未飽和土壤中，並經由SVE系統抽除，使土壤及地下水污染濃度逐步降低，達到預期整治成果。
在整治成本部份，本案例之污染整治工程經費每單位體積土壤約為384元/立方公尺，而文獻顯示國外相關整治案例整治經費單位體積成本為647~5174元/立方公尺 (約為15-120美元/立方碼)，與國外整治案例比較之下，本案例整治工程處理單位體積費用偏低，可能原因在於國內之處理設備、環境採樣檢測分析、人力工時及操作維護管理費均較國外低廉，使得整體處理成本較國外略低。

關鍵字

生物降解 ； 土壤蒸氣萃取法 ； 擬一階反應 ； 空氣注入法

並列摘要

In this study, a site contaminated with benzene, toluene and 1,2-dichloroethane was selected for investigation of the feasibility using the technologies of combining Air Sparging (AS) and Soil Vapor Extraction (SVE) system via the long-term in-situ soil and groundwater sampling. Also, the cost benefit of remediation technology of the combined system was evaluated.
Experimental results indicated that both removal of benzene and toluene in the unsaturated soil and groundwater attained 100% after the 11 months operation using the combined system of AS and SVE. Also, 100% of 1,2-dichloroethane in the aquifer was removed. Moreover, the degradation rates of toluene and benzene were fitted pseudo-first-order reaction model. The coefficient of reaction rate constants (k) of benzene and toluene were 0.0576 day-1 and 0.0586 day-1, respectively. In addition, the dissolved oxygen of groundwater was above 1 mg/L; therefore, the condition of groundwater transformed from originally anaerobic to aerobic after treatment. Meanwhile, the total bacterial count of microorganism increased from 40 CFU/mL to 1.7×105 CFU/mL which vastly increased by 4250 times, revealed that the function of biodegradation in situ occurred. On the other hand, the 2,282 kg of VOCs in the soil was drawn using the SVE system. Overall, the AS system would increase the dissolved oxygen of groundwater thus enhanced the degradation of organic contamination using in situ microorganisms. Also, it could strip the VOCs dissolved in the groundwater and vapor to unsaturated soil thus removed by SVE system. Gradually, the concentration of contaminants would decrease and reach the expected goal of the remediation.
In terms of the cost of site remediation, it took NT$ 384/m3 of soil of remediation engineering expenses, which is less than that of NT$ 647~5174/m3 of related aboard remediation cases. The reasons of low expenses of remediation engineering in this case were due to the lower cost of treatment equipments, environmental sampling and analysis, man-hour and maintenance compared to other countries.

並列關鍵字

Soil vapor extraction (SVE) ； Air sparging (AS) ； Biodegradation ； Pseudo-first order reaction

參考文獻

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