• Journal of Soil and Groundwater Environment
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• v.21 no.6
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• pp.101-113
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• 2016

To properly manage and remediate groundwater contaminated with chlorinated hydrocarbons such as trichloroethylene (TCE), it is necessary to assess natural attenuation processes of contaminants in the aquifer along with investigation of contamination history and aquifer characterization. This study evaluated natural attenuation processes of TCE at an industrial site in Korea by delineating hydrogeochemical characteristics along the flow path of contaminated groundwater, by calculating reaction rate constants for TCE and its degradation products, and by using geochemical and reactive transport modeling. The monitoring data showed that TCE tended to be transformed to cis-1,2-dichloroethene (cis-1,2-DCE) and further to vinyl chloride (VC) via microbial reductive dechlorination, although the degree was not too significant. According to our modeling results, the temporal and spatial distribution of the TCE plume suggested the dominant role of biodegradation in attenuation processes. This study can provide a useful method for assessing natural attenuation processes in the aquifer contaminated with chlorinated hydrocarbons and can be applied to other sites with similar hydrological, microbiological, and geochemical settings.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.261-266
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• 2001

Three innovative technologies to remediate trichloroethylene (TCE) in situ were (or currently are being) evaluated at a TCE-contaminated groundwater site at Edwards Air Force Base (AFB), California. The three technologies all make use of groundwater recirculation to obviate the need to pump contaminated groundwater to the surface fer treatment. The first technology, which implements aerobic cometabolic bioremediation to destroy TCE in situ, successfully reduced dissolved TCE concentrations from above 1 mg/L to 20-30 $\mu\textrm{g}$/L. The second technology, in-well vapor stripping (IWVS), is capable of treating dissolved TCE at concentrations in the tens to hundreds of mg/L. Finally, the third technology, bioenhanced in-well vapor stripping (BEHIVS): is a combination of the first two technologies, and is designed to reduce very high levels of TCE (tens to hundreds of mg/L) to concentrations that meet regulatory requirements 5 $\mu\textrm{g}$/L). Results of field evaluations of tile first two technologies are presented, and the design of the BEHIVS system. as well as model predictions of BEHIVS performance and the current status of the technology field evaluation. is discussed.

• Korean Journal of Microbiology
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• v.49 no.4
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• pp.336-342
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• 2013

Trichloroethylene (TCE) is a widely used substance in commercial and industrial applications, yet it must be removed from the contaminated soil and groundwater environment due to its toxic and carcinogenic nature. We investigated bacterial community structure, dominant bacterial strain, and removal efficiency in a TCE contaminated groundwater treatment system using immobilized carrier. The microbial diversity was determined by the nucleotide sequences of 16S rRNA gene library. The major bacterial population of the contaminated groundwater treatment system was belonging to BTEX degradation bacteria. The bacterial community consisted mainly of one genus of Pseudomonas (Pseudomonas putida group). The domination of Pseudomonas putida group may be caused by high concentration of toluene and TCE. Furthermore, we isolated a toluene and TCE degrading bacterium, named Pseudomonas sp. DHC8, from the immobilized carrier in bioreactor which was designed to remove TCE from the contaminated ground water. Based on the results of morphological and physiological characteristics, and 16S rRNA gene sequence analysis, strain DHC8 was identified as a member of Pseudomonas putida group. When TCE (0.83 mg/L) and toluene (60.61 mg/L) were degraded by this strain, removal efficiencies were 72.3% and 100% for 12.5 h, respectively. Toluene removal rate was 2.89 ${\mu}mol/g$-DCW/h and TCE removal rate was 0.02 ${\mu}mol/g$-DCW/h. These findings will be helpful for maintaining maximum TCE removal efficiency of a reactor for bioremediation of TCE.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.158-161
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• 2004

Chlorinated aliphatic hydrocarbons (CAHs) especially perchlorethylene (PCE) and trichlooethylene (TCE) are common groundwater contaminants in Korea. PCE and TCE were often reductively dechiorinated in an aquifer. Several isolates dechlorinate PCE to TCE or cis-1,2 dichloroethylene (c-DCE) were obtained from contaminated and pristine sites in USA and Europe. However in Korea, no information on indigenous microorganism being involved in reductive dechlorination of PCE and TCE is available and different dechlorinating microorganisms might be reside in Korea, since geochemical, and hydrogeological conditions are different, compared to those in the other sites. So we evaluate that: 1) if reductive dechlorinating microorganisms are present in PCE-contaminated site in Korea, 2) if so, what kinds of microorganisms are present; 3) to what extent PCE is reductively dechlorinated. As a results in some PCE-contaminated aquifers in Korea other dechlorinating microorganisms but Dehalococcoides ethenogenes may be responsible for PCE dechlorination. More detailed molecular works are required to evaluate that different dechlorinating microorganisms would reside in Korea.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.67-70
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• 2002

Remediation of groundwater contaminated with chlorinated organics, nitro aromatics, and heavy metals using zero valent iron (ZVI) filings has paid considerable attention in recent years. When the contaminants of high concentration leaked abundantly in subsurface environment, permeable reactive barrier technology using iron filing is taken a long time for the remediation of contaminated groundwater, The problem of contaminant shock is able to be solved using surfactant (hexadecyltrimethylammonium, HDTMA) modified bentonite (SMB) as immobilizing material. Therefore, the purpose of this research was to develop the combined remediation technology using conventional permeable reactive and immobilizing barrier for the enhanced decontamination of chlorinated compounds. Four column experiments were conducted to assess the performance of the mixed reactive materials with Ottawa sand, iron filing, and HDTMA-bentonite for trichloroethylene (TCE) removal under controlled groundwater flow conditions. TCE reduction rates with sand/iron filing/HDTMA-bentonite were highest among four column due to dechlorination of TCE by iron filing and sorption of TCE by SMB.

• Journal of Soil and Groundwater Environment
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• v.19 no.6
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• pp.80-90
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• 2014

The laboratory and field studies were conducted to identify an optimal injection concentration of nanoscale zero-valent iron particles (NZVI) and to evaluate the applicability of NZVI-based reactive zone technology to the site contaminated with trichloroethylene (TCE) DNAPL (Dense Non-Aqueous Phase Liquid). The laboratory test found an optimal injection concentration of NZVI of 5 g/L that could remove more than 95% of 0.15 mM TCE within 20 days. Eleven test wells were installed at the aquifer that was mainly composed of alluvial and weathered soils at a strong oxic condition with dissolved oxygen concentration of 3.50 mg/L and oxidation-reduction potential of 301 mV. NZVI of total 30 kg were successfully injected using a centrifugal pump. After 60 days from the NZVI injection, 86.2% of the TCE initially present in the groundwater was removed and the mass of TCE removed was 405 g. Nonchlorinated products such as ethane and ethene were detected in the groundwater samples. Based on the increased chloride ion concentration at the site, the mass of TCE removed was estimated to be 1.52 kg. This implied the presence of DNAPL TCE which contributed to a higher estimate of TCE removal than that based on the TCE concentration change.

• Journal of Soil and Groundwater Environment
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• v.18 no.6
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• pp.32-37
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• 2013

The scope of this study was to develop, design, and build an ex-situ remediation system of using the heating and water sparging treatment for the highly volatile DNAPL (Dense Non-Aqueous Phase Liquid) contaminated groundwater, and to conduct pilot testing at the site contaminated with DNAPL. The TCE (Trichloroethylene) removal was at the highest rate of 94.6% with the water sparging at $70^{\circ}C$ in the lab-scale test. The pilot-scale remediation system was developed, designed, and fabricated based on the results of the lab-scale test conducted. During the pilot-scale testing, DNAPL-contaminated groundwater was detained at heat exchanger for the certain period of time for pre-heating through the heat exchanger using the thermal energy supplied from the heater. The heating system supplies thermal energy to the preheated DNAPL-contaminated groundwater directly and its highly volatile TCE, $CCl_4$ (Carbontetrachloride), Chloroform are vaporized, and its vaporized and treated water is return edback to the heat exchanger. In the pilot testing the optimum condition of the HWSRS was when the water temperature at the $40^{\circ}C$ and operated with water sparging concurrently, and its TCE removal rate was 90%. The efficiency of the optimized HWSRS has been confirmed through the long-term performance evaluation process.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.542-547
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• 2000

It has become interested in the concept of permeable barriers for the containment and/or destruction of contaminated groundwater. The purpose of these trench-like barriers is to provide in situ capture and possibly destruction of the contaminant while preserving groundwater flow to uncontaminated zones. For instance, a trichloreethylene(TCE) plume may be contained by a permeable in which reactive iron reduces TCE to ethylene and ethane, compounds which can be easily biodegraded. The objective of this research is to examine the feasibility of using zero-valent iron as a clean-up media in permeable reactive barrier system. A series of laboratory column tests are performed. The concentration of influent and effluent water and the rate of clean up are analysed from these test results. The experimental result shows that the majority of the contamination in groundwater is removed in the reactor. And it shows the corresponding increase in the concentration of chloride ions through the reactor. Results from this study indicate that permeable reactive barrier containing admixtures of zero-valent iron and other materials can effectively clean up groundwater contaminated with organic compounds.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.6
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• pp.405-412
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• 2011

Environmental impact by proposed pump and treatment remediation of groundwater contaminated with TCE over 0.6 mg/L down to 0.005 mg/L was assessed for 30 years operation in an industrial park. Total amount of groundwater treated was $2.96{\times}10^7m^3$ and the amount of TCE removed was 17.6 kg at most. The life cycle assessment was used to estimate the environmental cost and environmental benefit and their effects on the environment could be analyzed. Most of the environmental cost was accrued from electricity generation for 30 years pump operation, which includes energy consumption, resources consumption such as coal, crude oil, emission of global warming gas and acid gas into air, waste water production, and waste generation. Environmental impact could be quantified with a Life Cycle Assessment (LCA) model for soil and groundwater remediation and normalized based upon consumption and emission quantities per capita in the world. Among the normalized values, acidification material release was the most significant.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.375-378
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• 2005

The objective of this study was to clarify the possibility of adsorption trichloroethylene (TCE) of pretreated granular activated carbon (GAC). The chemical solution used for the acidic treatment was phosphoric acid. In addition, the effect of ultrasound on GAC assessed in this experiments. It was observed that the adsorption of TCE were different based on pH value of pretreated GAC. However, natural water such as groundwater has various factors like ionic strength and hardness etc. Therefore, more laboratory work is needed to study about pretreated GAC.