benzene, toluene and 1,2-dichloroethane

• Main Authors: Ming-Che Yu, 游明哲
• Other Authors: none
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/86814600904950988964

碩士 === 國立中央大學 === 環境工程研究所碩士在職專班 === 95 === 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.