• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.350-353
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• 2004

This study was conducted for a rapid and simple method using GC/FID and SPME to dectermin gasonline and chlorinated solvents simultaneity. A sodium chloride concentration of 25%(vol/w) combined with such as magnetic stirried, an absorption time of 20min, an extraction temperature of 4$0^{\circ}C$, the volume of minimized 50mL of gaseous phase and a desorption time of 5min pleprovided the greatest sensitivity while maintaining analytical efficiency. Analytical parameter such as linearity was also evaluated. The linear range extend from 30 to 500ppb. The results of chlorinated solvents and gasoline mixed samples showed that solvents have been completely removed from the sample preparation step and more accurated than those obtained by the other methods.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.454-457
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• 2003

A new approach for groundwater treatment combines a permeable Fe(0) barrier to breakdown higher chlorinated solvents like PCE and TCE with a downgradient aerobic biological treatment system to biotransform less chlorinated solvents, such as DCE and vinyl chloride (VC). The expected bacterial performance downgradient of an Fe(0) barrier was evaluated through laboratory batch experiments with a toluene-degrading mixed culture that cometabolically transforms cis-1,2-DCE and VC. The amount of cis-1,2-DCE (initially at 2,000 ppb) and VC (initially at 2,000 ppb) transformed was controlled by the initial toluene (20,000 ppb) concentration. VC was removed much more effectively than Cis-1,2-DCE, and a higher toluene concentration in comparison to the co-substrate concentrations was needed for complete co-substrate removal. Overall, the coupling of an Fe(0) barrier and subsequent biodegradation appears feasible for remediation of complex mixtures of chlorinated solvents and petroleum hydrocarbons in groundwater

• Journal of the Korean GEO-environmental Society
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• v.11 no.5
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• pp.61-67
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• 2010

In this study, Solid-phase microextraction (SPME) with GC/FID was studied as a possible alternative to liquid-liquid extraction for the analysis of chlorinated solvents (PCE and TCE) and these by-products (cis-DCE, VC, and Ethylene). Experimental parameters affecting the SPME process (such as kind of fibers, adsorption time, desorption time, volume ratio of sample to headspace, salt addition, and magnetic stirring) were optimized. Experimental parameters such as CAR/PDMS, adsorption time of 20 min, desorption time of 5 min at $250^{\circ}C$, headspace volume of 50mL, sodium chloride (NaCl) concentration of 25% combined with magnetic stirring were selected in optimal experimental conditions for analysis of chlorinated solvents and these by-products. The general affinity of analytes to CAR/PDMS fiber was high in the order PCE>TCE>cis-DCE>VC>Ethylene. The linearity of $R^2$ for chlorinated solvents and these by-products was from 0.912 to 0.999 when analyte concentrations range from $10{\mu}g/L$ to $500{\mu}g/L$, respectively. The relative standard deviation (% RSD) were from 2.1% to 3.6% for concentration of $500{\mu}g/L$ (n=5), respectively. Finally, the limited of detection (LOD) observed in our study for chlorinated solvents and these by-products were from $0.5{\mu}g/L$ to $10{\mu}g/L$, respectively.

• Clean Technology
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• v.3 no.2
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• pp.57-73
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• 1997

Metal cleaning process is a technology which removes oil, dust and soil etc. on the surface of metal utilizing cleaning agents. These contaminants disturb the following processes such as plating and painting etc. if they are not removed. Thus, metal cleaning is typically an environmentally hazardous activity. Until recently, vapor degreasers as utilizing chlorinated solvents have been relatively cheap, extraordinarily versatile and waste disposal costs have been perceived as insignificant. Today, however, it is readily apparent that Industry's reliance upon chlorinated solvents as metal cleaners have resulted in a myriad of environmental, health and safety concerns. Therefore, this paper studies on a parameter and a sort of the alternative cleaning agents for the optimum cleaners. Also, a great deal of effort has been devoted to developing alternative metal cleaning technologies in advanced countries and some processes are being commercialized among them. We are going to consider alternative aqueous cleaning agents replacing organic chlorinated solvents and to pursue a domain application through a successful improvement case.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.440-444
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• 2003

A new approach for ground water treatment combines a permeable Fe(0) barrier to breakdown higher chlorinated solvents like PCE and TCE with a down gradient aerobic biological treatment system to biotransform less chlorinated solvents, such as DCE and vinyl chloride (VC). The expected bacterial performance down gradient of an Fe(0) barrier was evaluated through laboratory batch experiments with a toluene-degrading mixed culture that cometabolically transforms cis-1,2-DCE and VC. The amount of cis-1,2-DCE (initially at 2,000 ppb) and VC (initially at 2,000 ppb) transformed was controlled by the initial toluene(20,000 ppb) concentration. VC was removed much more effectively than Cis-1,2-DCE, and a higher toluene concentration in comparison to the co-substrate concentrations was needed for complete co-substrate removal. Overall, the coupling of an Fe(0) barrier and subsequent biodegradation appears feasible for remediation of complex mixtures of chlorinated solvents and petroleum hydrocarbons in groundwater.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2007.05a
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• pp.530-536
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• 2007

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.391-394
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• 2003

The applicability of in situ microbial filter or biobarrier technology for the remediation of soil and groundwater contaminated with chlorinated solvents was investigated. The efficiency and rates of reductive dechlorination of chlorinated solvents are known to be highly dependent on hydrogen concentration. In this study, the effect of electron donors on the reductive dechlorination of PCE was investigated using vermicompost (worm casting) and peat as permeable reactive barrier medium The effect of organic acids (lactate, butyrate and benzoate), yeast extract and vitamin $B_{l2}$ on the reductive dechlorination was investigated. Compared to the control (no electron donor added), addition of electron donors stimulated the dechlorinated rate. Among the electron donor treatments, lactate/benzoate amendment exhibited the highest dechlorination rate. Since vermicompost and peat are inexpensive and biodegradable and have high sorption capacity, they could be successfully used as biobarrier media, especially when electron donors (for example, lactate/benzoate) are added.d.

• Journal of Soil and Groundwater Environment
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• v.15 no.2
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• pp.10-17
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• 2010

Advanced oxidation processes (AOPs) have advantages to reduce the processing time and mineralize contaminants dissolved in groundwater. Recently, remediation techniques for organic contamination in groundwater have been studied, and technology using $UV/H_2O_2$ is generally accepted as one of the most powerful and reliable alternative for the remediation of groundwater contamination. In this study, $UV/H_2O_2$ technology, which generates hydroxyl radical ($\cdot$ OH) as known for strong non-selective oxidant, was used to degrade chlorinated solvents (TCE and PCE), and it was expanded to apply continuous stirred tank reactor (CSTR) system (i.e. combinations of three CSTR). The tested parameters for CSTR system were retention time and groundwater/$H_2O_2$ injection volume ratio. To find optimum parameters for CSTR system, various retention time (6 min ~ 90 min) and groundwater/$H_2O_2$ injection volume ratio (5/1 ~ 119/1) were tested. Other conditions for CSTR were adapted from the batch test results, which concentration of $H_2O_2$ and UV dose were 29.4 mM (0.1%) and 4.3 kWh/L, respectively. Based on the experimental results, the optimum parameters for CSTR system were 20 min for retention time and 119/1 for groundwater/$H_2O_2$ injection volume ratio. Applying these optimum conditions, chlorinated solvents (TCE and PCE) were removed at 99.9% and 99.6%. Moreover, the effluent concentrations of TCE and PCE are 0.036 mg/L and 0.087 mg/L, respectively, which are satisfied the regulatory level (TCE 0.3 mg/L, PCE 0.1 mg/L). Consequently, the CSTR system using $UV/H_2O_2$ technology can achieve high removal efficiency in the event of treatment of groundwater contaminated by chlorinated solvents (TCE and PCE).

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.6
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• pp.665-674
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• 2000

A major source of the hazardous waste generated is from chemical industries producing plastics, herbicides, pesticides and chlorinated solvents. All of these processes produce a class if hazardous waste termed the chlorinated hydrocarbons(CHCs), either directly or from undesirable side reactions. In this study, we investigated the destruction characteristics of hazardous waste through incineration. A nonequilibrium combustion model was used to describe the effect of the chemical kinetics due to the flame inhibition characteristics of $CCl_4$ which was used as the surrogate of hazardous waste. A parametric screening studies was made in a dump incinerator proposed in this study. The dump incinerator showed high $CCl_4$ DRE(Destruction and Removal Efficiency) as 5 nines. $CCl_4$/CH$_4$ ratio appeared to be most important in the destruction of $CCl_4$ through incineration.

• Bulletin of the Korean Chemical Society
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• v.18 no.1
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• pp.80-86
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• 1997

Nine new solubility-increased container hosts having eight undecyl substituents were synthesized and characterized. 1H NMR spectral data showed integral inclusion state of carceplexes and their stability. 1H NMR chemical shifts of guest DMA were correlated to the host's cavity dimensions shrinked by constrictive binding. Carceplex and hemicarcerand showed their distinctive FD mass spectra.