Application of in-situ bioremediation technology to remediatetrichloroethylene-contaminated groundwater

• Main Authors: Shih-hao Tseng, 曾士豪
• Other Authors: C. M. Kao
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/nfcqk6

碩士 === 國立中山大學 === 環境工程研究所 === 97 === Chlorinated organic compounds are widely used in various industrial processes. Due to their high density and low water solubility, they are mainly utilized as cleaning solvents in dry cleaning operations, as well as semiconductor manufacturers. Many chlorinated organic compounds spilled sites contain residuals, which present in a pure liquid phase (dense non-aqueous phase liquids, DNAPLs). Trichloroethylene (TCE) is the most typical compound as a result. In situ bioremediation has been successfully used for the removal of TCE. This process has several advantages, such as relative simplicity, low cost, and potentially remarkable efficiency in contamination removal than others. By using the in situ bioremediation to remediate TCE contaminated groundwater, it must ensure (1) biodegradability of contaminants, and the presence of a competent biodegrading population of microorganisms, (2) presence of electron acceptors, and (3) environment condition and, nutrient sources. A field study for biodegradation TCE through molasses injection was conducted at the industrial trading estate in Kaohsiung City. The study included electronic products, semiconductor, nicety optical industry and so on. Molasses, nitrate and phosphate were introduced from injection well (BW1-1 and BW2-1) into aerobic and anaerobic groundwater contaminated site. In the aerobic zone, there were four wells being monitored: BW1-1, C029, BW1-2 and BW1-3. After 213 days of biostimulation treatment, TCE concentration detection results showed TCE concentrations in all wells monitored. BW1-1 and C029, there was a sharp decrease from 0.0853 mg/L to below the detection limit and from 0.1340 mg/L to 0.0038 mg/L. BW1-2 and BW1-3 showed a slight decrease from 0.0668 mg/L to 0.0211 mg/L and from 0.0323 mg/L to 0.0161 mg/L. After treatments, TCE concentrations in all wells monitored were dropped to 0.05 mg/L. In anaerobic zone, there were four wells being monitored: BW2-1, SW-4, BW2-2 and BW2-3. After 193 days of biostimulation treatment, TCE concentration detection results showed TCE concentrations in all wells monitored. BW2-1, SW-4, BW2-2 and BW2-3 all had a slight decrease from 0.0399 mg/L to 0.0043 mg/L, from 0.14603 mg/L to 0.0687 mg/L, from 0.1030 mg/L to 0.0365 mg/L and from 0.0492 mg/L to 0.0289 mg/L. According to the results from BIOCHLOR modeling, elevated aqueous concentration of chloroethenes with a classical reduction pathway for TCE leading to an accumulation of vinyl chloride and ethane. All the results revealed that bioremediation technology is one of the more feasible approaches to clean up TCE contaminated groundwater in this field.