Application of long-lasting substrate to remediate TCE-contaminated groundwater

• Main Authors: Yu-ling Huang, 黃宇伶
• Other Authors: Jimmy C. M. Kao
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/33274200262965829438

碩士 === 國立中山大學 === 環境工程研究所 === 101 === Chlorinated organic solvents such as trichlorethene (TCE) has the potential of gene mutation and carcinogenic toxic characteristics. Leakage of TCE into the subsurface will cause the contamination of drinking water and result in the human health problems. In this study, emulsified oil and nanoscale zero-valent iron (nZVI) were produced and combined to form the long-lasting substrate (LS), which can enhance the growth of TCE-degraders. TCE concentrations in groundwater can be reduced through the reductive dechlorination process under anaerobic conditions and through the physical adsorption mechanism. Thus, the spreading of TCE can be effectively controlled. In this study, batch experiments were performed to evaluate the characteristics of the developed substrates. Furthermore, denaturing gradient gel electrophoresis (DGGE) was adopted to investigate the variations in microbial communities during the TCE dechlorination. The results from optical microscope observation show that the emulsified oil coated with nZVI had an averaged particle diameter of 0.705 μm. Results from the suspension test show that only 3% of nZVI remained in the suspension after 6 days in the test using pure nZVI. However, more than 30% of the nZVI remained in the suspension after 30 days when the LS was used. Results indicate that the LS avoided the nZVI agglomeration between nZVI particles. This would increase the opportunities for nZVI to contact with contaminants. Results of the batch experiments show that the LS could enhance the TCE removal and caused a significant TCE removal efficiency. Approximately 99% of the TCE can be removed after 130 days of operation, and the remaining TCE concentrations met the groundwater pollution control standards (0.05 mg/L). Results of microbial analysis and the DNA sequencing test show that the LS can enhance the growth of TCE-degraders (including Dechloromonas sp.、Clostridium sp.、Perchlorate-reducing bacterium、Beta proteobacterium、Delta proteobacterium、Burkholderiales bacterium、Geobacter lovleyi sp.、Aquabacterium parvum strain、Acidovorax sp.、Iron-reducing bacterium、Methanogenic bacterium). Results confirmed that LS enhance the growth of TCE-degrading bacteria, and achieved effective TCE degradation rates.