• Journal of Preventive Medicine and Public Health
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• v.35 no.3
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• pp.221-228
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• 2002

Objectives : The purpose of this study was to find the protective effects of garlic on the halogenated hydrocarbon induced hepatotoxicities, and the possible protection mechanisms involved. Methods : Male Sprague-Dawley rats received garlic (0.5%) or regular diet, for 4 weeks. This was followed by a single dose of corn oil (the controls), carbon tetrachloride (400mg/kg body weight) and trichloroethylene (2,000mg/kg body weight) being administered to each diet group. Blood samples were collected 24 hours fellowing the administration, and the serum aspartate aminotransferase (AST) and alanine aminotransferase (ALD activities measured. The liver samples were studied for their cytochrome P450 and CYP2E1 contents, lipid peroxidation and histopathology. Results : rho results for the group receiving the 9.5% garlic diet showed a slight decrease of CYP2E1 expression compared with the regular diet group. Carbon tetrachloride was significantly decreased the CYP2E1 contents in both the regular and garlic diet groups, but the trichloroethylene remained unchanged. Garlic did not decrease the lipid peroxidation of the liver in the control group, but attenuated the increase of lipid peroxidation caused by carbon tetrachloride. Garlic attenuated the increase of both the serum AST and ALT activities caused by carbon tetrachloride. The histopathelogical observations also showed that garlic attenuated centrilobular necrosis and vacuolar degenerative changes significantly in the carbon tetrachloride treated group. Conclusions : The results indicate that garlic attenuates the carbon tetrachloride-induced hepatotoxicity, through the prevention of the metabolic activation and lipid peroxidation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.12
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• pp.142-149
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• 2008

This paper proposes an effective decomposition method of trichloroethylene using pellet packed-bed non-thermal plasma reactor and catalyst. For that, two types of reactors filled with manganese dioxide and alumina pellets are designed. When $MnO_2$ packed reactor is used, TCE decomposition rate is high due to the generation of oxygen atom radicals at the surface of catalyst during ozone decomposition. In addition, When $Al_2O_3$ packed reactor is used, TCE is oxidized into DCAC and it did not decomposed into small molecules such as COx and $Cl_2$. However, the plasma processed gas using $Al_2O_3$ packed reactor is passed through the $MnO_2$ catalyst reactor, which is placed at the downstream of plasma reactor, the decomposition rate increased as well due to oxygen atom radicals through ozone decomposition. Therefore, the adequate use of $MnO_2$ catalyst in the plasma process is very promising way to increase the decomposition efficiency.

• Journal of Soil and Groundwater Environment
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• v.17 no.1
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• pp.33-41
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• 2012

Nanoscale zero-valent iron (nZVI) has recently received much attention for remediation of soil and groundwater contaminated with trichloroethylene (TCE). But there have been many debates on the toxic or inhibitory effects of nZVI on the environment. The objective of this study was to investigate the effects of nZVI on the activity of Geobacter lovleyi and to determine the potent effect of combination of abiotic and biotic treatment of TCE dechlorination. TCE degradation efficiencies of Geobacter lovleyi along with nZVI were more increased than those when nZVI was solely used. The amount of total microbial protein was increased in the presence of nZVI and hydrogen evolved from nZVI was consumed as electron donor by Geobacter lovleyi. In addition, dechlorination of TCE to cis-DCE by Geobacter lovleyi along with nZVI in respiking of exogenous of TCE shows that the reactivity of Geobacter lovleyi was also maintained. These results suggest that the application of Geobacter lovleyi along with nZVI for the dehalorination is beneficial for the enhancement of TCE degradation rate and reactivity of Geobacter lovleyi.

• 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.

• 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 Korea Soil Environment Society
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• v.1 no.1
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• pp.11-17
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• 1996

Trichloroethylene(TCE) is the organic compound which is used variously at the industrial areas. It contaminates soils and groundwater by leaked storage tank, careless treatment in field and the effluent from waste landfills. This study was carried out to identify adsorptive behavior of TCE by soil. Batch experiments were conducted at different soil-organic matter content and lime treatment to determine Freundlich isothermal adsorption equation constant, k and n, for TCE. Sewage sludge cake was applied to make different soil-organic matter content with the level of Oton/ha(S1), 50ton/ha(S2), 100ton/ha(S3). Lime(calcium hydroxide) was treated with the level of 2ton/ha, 4ton/ha, 6ton/ha, 10ton/ha. Freundlich isothermal adsorption equations obtained from experiment with sewage sludge cake were as follows (on condition that the level of TCE applied to soil ranged from 0.5ng/g soil to 2.5 ng/g soil.) : S1 :x/m = 0.393 $C^2$, S2 : x/m = 0.436 $C^2$, S3 : x/m = 0.636 $C^2$Value of k was increased in higher order of 51, 52, 53 with increased level of sewage sludge cake application. From this results, soil which was applied higher level of sewage sludge cake had a good ability on TCE adsorption. With increased the level of lime application, pH of the soil was increased and the ability of the soil in TCE adsorption was decreased.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.10
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• pp.873-882
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• 2009

Sonolysis of TCE (Trichloroethylene) was performed in 584 kHz rectangular reactor. At first, the effect of acoustic power and aqueous temperature which are both important factors to operate ultrasound system on sonolysis of TCE were examined under one side irradiation condition. First degradation rate constants of TCE and chloride yields were increased with increasing acoustic power from 100 to 300 W. And increasing the aqeuous temperature resulted in the increase of first degradation rate constants of TCE and the decrease of chloride yield. Sonolysis of TCE was performed under multi ultrasound irradiation conditions that total acoustic power of 300 W was distributed according to the number of irradiation sides. First degradation rate constants of TCE followed the order 4 sides > 3 sides > 1 side > 2 sides (parallel) > 2 sides (orthogonal). When comparing the experimental results under parallel and orthogonal irradiation conditions of 2 sides with 300 and 450 W, first degradation rate constants of TCE were similar, while production rate constants of hydrogen peroxide were more higher at parallel conditions compared to orthogonal conditions.

• Journal of Environmental Health Sciences
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• v.40 no.5
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• pp.385-396
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• 2014

Objectives: By conducting a meta-analysis of cohort studies reporting standardized mortality ratios (SMRs) for workers exposed to trichloroethylene, we attempted to adjust for healthy hired effect by applying the same methods as described in a recent report from the Agricultural Health Study. Methods: Among all cohort studies that evaluated the association between all cancer, non-Hodgkin's lymphoma (NHL), kidney cancer, liver cancer and occupational exposure to trichloroethylene, a total of 10 studies reporting SMR values were selected. A random-effects model was used to estimate the summary SMRs or rSMRs and 95% confidence intervals. Relative SMR ($rSMR=SMR_x/SMR_{not\;x}$) was calculated comparing observed and expected counts for all cancer, NHL, kidney cancer, and liver cancer with an independent referent set of values consisting of the observed and expected counts for other causes. Results: The SMR values for all causes ranged from 0.68 to 1.03, suggesting moderate to weak healthy worker effect for the selected studies. When the healthy worker hire effect was taken into account, the summarized risk became statistically significant; the summary SMR of all cancer was 0.95 (0.91-1.00) and the summary rSMR of all cancer was 1.10 (1.04-1.15). The summary SMR of NHL was 1.04 (0.93-1.14) and the summary rSMR of NHL was 1.23 (1.04-1.46). The summary SMR of kidney cancer was 1.08 (0.88-1.33) and the summary rSMR of kidney cancer was 1.23 (1.02-1.49). The summary SMR of liver cancer was 0.88 (0.78-0.99), and the summary rSMR of liver cancer was 0.95 (0.84-1.07). Conclusion: The rSMR method is useful to determine summary risk adjusted for healthy worker effect through meta-analysis.

• 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.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.3-10
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• 2002