Title page for etd-0715116-163713


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URN etd-0715116-163713
Author Yu-lin Wu
Author's Email Address No Public.
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Department Environmental Engineering
Year 2015
Semester 2
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title Application of emulsified substrate with pH buffering capacity to enhance the bioremediation efficiency of chlorinated-solvent contaminated groundwater
Date of Defense 2016-07-19
Page Count 118
Keyword
  • Chlorinated solvents
  • trichloroethylene
  • vegetable oil
  • buffer solution
  • molecular biological techniques
  • Abstract Groundwater at many existing and former industrial areas and disposal sites are contaminated by chlorinated solvents that were released into the environment. In this study, trichloroethylene (TCE) was used as the target compound. Application of in situ anaerobic bioremediation is a feasible technology to remediate TCE-contaminated groundwater. However, enhanced in situ bioremediation requires the injection of primary substrates, which would cause the acidification and odor problems of the subsurface environment. This would deteriorate the groundwater quality and cause the increase in maintenance cost. The objective of this microcosm study was to develop a substrate and buffer solution to enhance the reductive dechlorination of TCE. The buffered colloid substrate can be applied in the saturated zone, which can release substrate from the colloid in the saturated zone. Furthermore, the buffered colloid has the capability for pH control and prevent the decrease in pH value in groundwater. Because vegetable oil has a lower iodine value, it was used as the source of carbon substrate to prevent the acidification problem after its application. Molecular biological techniques were applied to evaluate the variations in microbial diversity during the microcosm study. Results indicate that the emulsified buffered substrate could maintain its stablilization within a 48-hr period. The average diameter of the oil globule was around 0.539 μm analyzed by dynamic light scattering instrument. Up to 93% of TCE can be removed in microcosm with emulsified buffered substrate addition and the pH was maintained at 7 after 140 days of operation. The neutral pH value also resulted in a higher microbial diversity in microcosms. Results from the real-time PCR analyses show that the populations of Dehalococcoides spp. (DHC) increased from 2.3 × 102 on day 0 to 5 × 103 gene copies/g on day 120. The results indicate that the developed emulsified buffered substrate was able to enhance the DHC and also caused the increase in anaerobic TCE dechlorination rate.
    Advisory Committee
  • Kuo-Lin Huang - chair
  • Andy Hong - co-chair
  • Cheng-rong Jiang - co-chair
  • Chiu-Wen Chen - co-chair
  • Chil-Ming Kao - advisor
  • Files
  • etd-0715116-163713.pdf
  • Indicate in-campus at 99 year and off-campus access at 99 year.
    Date of Submission 2016-08-15

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