• Journal of Korean Society for Atmospheric Environment
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• v.13 no.1
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• pp.31-40
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• 1997

This study was conducted to investigate the biodegradation of gaseous trichloroethylene (TCE) and tetrachloroethylene (PCE) in an activated carbon biofilter inoculated with phenol-oxidizing microorganisms and to study the effect of surfactant concentration below its critical micelle concentration (CMC) on the re-moval efficiency of TCE or PCE. The investigation was conducted using two specially built stainless steel biofilters, one for TCE and the other for PCE, at residence times of 1.5~7 min. The removal efficiency of gaseous TCE was 100％ at a residence time of 7 min and its average inlet concentration of 85 ppm. For gaseous PCE, 100％ removal efficiency was obtained at residence times of 4~7 min and its average concentrations of 47~84 ppm. It was found that adsorption by GAC was a minor mechanism for TCE and PCE removal in the activated carbon biofilters. Transformation yields of gaseous TCE and PCE were about 8~48 g of TCE/g of phenol and 6~25g of PCE/g of phenol, according to residence times. This values showed one or two orders of magnitude less than aqueous TCE degradation. The TCE and PCE activated carbon biofilter performances were observed to be a little enhanced but not significantly, when the surfactant was introduced at concentrations of 5~50 mg/L.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.11
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• pp.1146-1153
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• 2008

Numerical simulation was carried out to study the trichloroethylene (TCE) degradation by permeable reactive barrier (PRB), and revealed the effect of concentration of TCE, iron medium mass, and concentration of iron-reducing bacteria (IRB). Newly developed model was based on axial dispersion reactor model with chemical and biological reaction terms and was implemented using MATLAB ver R2006A for the numerical solutions of dispersion, convection, and reactions over column length and elapsed time. The reaction terms include reactions of TCE degradation by zero-valent iron (ZVI, Fe$^0$) and ferrous iron (Fe$^{2+}$). TCE concentration in the column inlet was maintained as 10 mg/L. Equation for Fe$^0$ degradation includes only TCE reaction term, while one for Fe$^{2+}$ has chemical and biological reaction terms with TCE and IRB, respectively. Two coupled equations eventually modeled the change of TCE concentration in a column. At Fe$^0$ column, TCE degradation rate was found to be more than 99% from 60 hours to 235 hours, and declined to less than 1% in 1,365 hours. At the Fe$^{2+}$ and IRB mixed column, TCE degradation rate was equilibrated at 85.3% after 210 hours and kept it constant. These results imply that the ferrous iron produced by IRB has lowered the TCE degradation efficiency than ZVI but it can have higher longevity.http://kci.go.kr/kciportal/ci/contents/ciConnReprerSearchPopup.kci#

• Journal of the Korean GEO-environmental Society
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• v.13 no.11
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• pp.37-42
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• 2012

This study investigated the use of Geobacter lovleyi with TBOS(Tetrabutoxysilane) for TCE(Trichloroethylene) dechlorination. The TCE dechlorination by Geobacter lovleiy was mathematically described as the independent variables such as initial concentration of TCE, protein mass of Geobacter lovleyi and initial concentration of TOBS, and these were modeled by the use of response surface methodology(RSM). These experiments were carried out as a Box-Behnken Design(BBD) consisting of 15 experiments. The application of RSM yielded the following equation, which is empirical relationship for the dechlorination efficiency($Y_1$, %) of TCE and first order kinetic constant of TCE($Y_2,\;d^{-1}$) by independent variables in coded unit : $Y_1=-11.50X_1$(initial concentration of TCE) + $4.25X_2$(protein mass as Geobacter lovleyi injected mass) - $4.75X_3$(initial concentration of TBOS) - ${6.58X_1}^2$ - ${8.58X_2}^2$ + 93.67, $Y_2=-10.92X_1+5.06X_2-4.89X_3-{4.93X_3}^2-2.19X_1X_2+2.54X_1X_3-2.19X_2X_3+16.71$. In this case, the value of the adjusted determination coefficient(adjusted $R^2$= 0.975 and 0.934) were closed to 1, showing a high significance of the model. Statistical results showed the order of TCE dechlorination at experimental factors to be initial TCE concentration > initial TBOS concentration > protein mass, but the interaction effects were non-significant.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.6
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• pp.991-1000
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• 2000

Methanotrophic consortium utilizing methane as the primary carbon source and secreting soluble methane monooxygenase (sMMO) was immobilized on celite R-635 to continuously treat a wastewater containing trichloroethylene (TCE). With influent 2 ppm of TCE. 80.4 and 84.5% of TCE was degraded in 6 and 20 hour of hydraulic retention time (HRT). respectively. and the removal efficiency of TCE was increased with an increase in HRT in methanotrophic consortium biofilm reactor (MCBR). With influent 5 ppm of TCE and 10 hour of HRT. average efficiency of TCE removal was decreased in initial stage. but gradually increased to 81%. TCE was degraded to 88.5 and 96.5% with 10 and 15 hour of HRT. respectively. when methane was supplied alternately with continuous oxygen supply at influent 5 ppm of TCE. The efficiency of TCE degradation was decreased probably because oxidation reaction of methane was proceeded slowly on MMO. when high concentration of methane was supplied with depletion of oxygen. As results of the pilot-scale study. biodegradation of TCE by MCBR system might be feasible at full-scale operation.

• Solar Energy
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• v.15 no.2
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• pp.65-75
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• 1995

We have summarised some important aspects of our recent basic and applied studies in the area of photocatalytic detoxifcation with Degussa P25 titanium dioxide($TiO_2$) being the photocatalyst. Heterogeneousphotocatalytic decompositions of two components such as TCE-chloroform, TCE-phenol and TCE-benzene as well as single component organic, TCE, chloroform and $CCl_4$ were carried out to investigate the effect of additional compound on the TCE decomposition rate. In laboratory experiments, the optimum flow rate of TCE solution was $200cm^3/min$ with annular photoreactor in the presence of 0.1 wt% $TiO_2$ powder under illumination. It was observed that the second compound such as $CHCl_3$, phenol and benzene has a negative effect on the TCE decomposition rate. Result presented that TCE decomposition ratio was increased at low pH in the TCE-phenol two component solution. It could be shown that the photocatalytic reactor exhibits technical feasibility of detoxifying the multicomponent under proper experimental conditions.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1993.05a
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• pp.33-41
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• 1993

The objectives of this experiment performed were to determine the potential using of solar radiation to destroy organic contaminants in water by photolysis and to develop the process and improve its performance. We used lab, scale of recirculation photoreactor with 30, 50, 80ppm initial concentration of TCE and Ti $O_2$ anatase, respectively. Adsorption constant, reaction constant were obtained and compared using the Langmuir-Hinshelwood kinetics equation. Ti $O_2$ anatase demonstrated the highest conversion ratio co TCE among Ti $O_2$ anatase, ZnO and F $e_2$ $O_3$ in this experiment. It was shown that in case of two component system, TCE+ phenol, as the concentration of phenol increased in the feed solution, TCE decomposition rate decreased.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.413-416
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• 2003

Micellar enhanced ultrafiltration(MEUF) is a surfactant-based separtaion technique which can remove dissolved organics or multivalent ions from water. In this study, trichloroethylene(TCE) and chromate were simultaneouly removed using MEUF and cetyltrimethylammoniun chloride (CPC) was used as a surfactant. The removal efficiency of chromate was 99% and that of TCE was more than 80%. The presence of TCE or chromate did not affect removal efficiency of each pollutants because the predominat mechanism of TCE and chromate are different.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.1
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• pp.37-46
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• 2012

The degradation characteristics of TCE by Ferrate(VI) oxidation have been studied. The degradation efficiency of TCE in aqueous solution was investigated at various pH values, Ferrate(VI) doses, initial concentrations of TCE and aqueous solution temperature values. GC-ECD was used to analyze TCE. The optimum conditions of TCE degradation were obtained pH 7.0 and $25^{\circ}C$ in aqueous solution. Also, the experimental results showed that TCE removal efficiency increased with the decrease of initial concentration of TCE. And intermediate products were identified by GC-MS techniques. Ethyl Chloride, Chloroform, Ethylene, 1,2-dichloroethane and 1,1,2-trichloroethane were identified as a reaction intermediate, and $Cl^-$ was identified as an end product.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.168-171
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• 2003

This research was conducted to assess the performance of the mixed reactive materials with sand, iron filings, and HDTMA-bentonite for trichloroethylene (TCE) and chromate removal under controlled groundwater flow conditions. TCE and chromate removal rates with the mixtures of iron filing/HDTMA-bentonite were highest among four columns due to reduction by iron filings and sorption by HDTMA-bentonite. The greater capacity of the mixed iron filing/HDTMA-bentonite compared HDTMA-bentonite was due to an enhanced chromate reduction in addition to chromate sorption. The presence of chromate caused greater inhibition of TCE removal in the column with iron filings, while the presence of TCE caused less inhibition of TCE. Also, nitrate caused the decrease in TCE removal relative to chloride. Nitrate ions may also significantly affect TCE reduction rates by competing for electrons with the chlorinated compounds. The anion and co-existed contaminants competing effects should be considered when designed permeable reactive barriers (PRBs) composed of zero valent iron for field applications to remediate TCE and chromate.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.362-365
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• 2002

토양의 물리/화학적 특성에 따른 토양의 유기오염물 흡착능 변화를 규명하기 위하여, 토양 내 clay 함량 및 유기물 함량변화, 수용액 내 TCE 농도변화에 따른 TCE 의 토양내 흡착량 변화를 측정하였다. 수용액의 pH와 실내온도는 일정하게 유지시켰으며 clay는 표면적이 다른 Ca-montmorillonite, Na-montmorillonite, kaolin을 이용하였고, 유기물질로는 활성탄을 사용하였다. 일정한 토양성분과 실제토양에 대해 수용액 내 TCE의 농도를 변화시켜 농도변화에 따른 흡착량 변화를 측정하였다. 실험결과 유기물과 점토함량의 증가에 따라 흡착량은 모두 증가하였으나 활성탄에 의한 TCE 흡착량이 점토에 비해 매우 높았으므로 유기물에 의한 TCE 흡착영향이 점토에 의한 흡착 영향보다 큰 것으로 나타났다. TCE 농도변화에 따른 흡착결과는 실제토양과 모사토양에서 모두 농도가 증가함에 따라 흡착 증가율이 증가하다가 감소하는 Langmuir isotherm 형태를 보여 주었다.