Title page for etd-0723112-125759


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URN etd-0723112-125759
Author Shang-en Wang
Author's Email Address No Public.
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Department Biological Sciences
Year 2011
Semester 2
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title Microbial monitoring of bioremediation of a 1,2-dichloroethane-contaminated site
Date of Defense 2012-07-05
Page Count 103
Keyword
  • Desulfitobacterium spp.
  • 1,2-dichloroethane
  • bioremediation
  • realtime-PCR
  • Dehalococcoides spp.
  • DGGE
  • Abstract The aim of this study was to access the efficacy of an enhanced in situ bioremediation technology at a 1,2-dichloroethane (1,2-DCA) polluted site in southern Taiwan. A water-soluble substrate was injected into the groundwater to provide carbon sources for microbial growth. After substrate injection, increased total organic carbon (TOC) concentrations and microbial populations including Dehalococcoides spp. and Desulfitobacterium spp. were observed in the groundwater. Microbial diversity was analyzed using denaturing gradient gel electrophoresis (DGGE) and 16S rDNA sequencing to identify the bacterial strains. The results showed that after 4.5 months of substrate injection, the reduction-oxidation potential (ORP) changed from aerobic to anaerobic conditions. The less oxygen-tolerable 1,2-DCA degrading bacteria Dehalococcoides spp. started to accumulate in groundwater. However, the more oxygen-tolerable Desulfitobacterium spp. didn’t show a prominent change, although the ORP was suitable for Desulfitobacterium spp. to carry out reductive dechlorination. The DGGE results indicate that with the injected carbon sources and mineral nutrients, both the groundwater microbial diversity and the amount of dominant bacteria were increased. The 16S rDNA sequencing demonstrated that the amount and diversity of 1,2-DCA degradation-related bacteria also increased with the injection of substrate. Six groups of 1,2-DCA degradation related reactions were found: dechlorination, chlorinated-compound degradation, denitrification, iron-reduction, sulfate-reduction and methane-utilizing. Four species that can directly degrade 1,2-DCA were found: Dehalobacter sp., Dehalococcoides sp., Nitrosospira sp. and Pseudomonas sp. Moreover, 11 methane-utilizing bacterial species were also discovered. The presence of these methane-utilizing bacteria not only might assist the process of denitrification and sulfate-reduction, but also could diminish the emission of the greenhouse gas. The results of this study confirmed that the addition of substrates could affect the groundwater oxidation-reduction state and enhance the bioremediation at the 1,2-DCA-contaminated site. Thus, enhanced in situ bioremediation is a feasible technology for site remediation.
    Advisory Committee
  • Jimmy C. M. Kao - chair
  • Chi-hsin Hsu - co-chair
  • Jong-kang Liu - advisor
  • Files
  • etd-0723112-125759.pdf
  • Indicate in-campus at 99 year and off-campus access at 99 year.
    Date of Submission 2012-07-23

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