• Journal of Soil and Groundwater Environment
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• v.15 no.6
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• pp.53-63
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• 2010

Pneumatic fracturing is an emerging tool to enhance the remediation efficiency of contaminated unsaturated zones by injecting high pressure air and inducing artificial fracture networks. Pneumatic fracturing is reported to be well suited for the cases where the contaminated unsaturated zone thickness is less than 5 m as many contaminated domestic sites in Korea. Nevertheless, there have been almost no studies carried out on the site-specific efficiency and the optimized design of pneumatic fracturing considering the unsaturated zone characteristics of Korea. In this study, we employ numerical simulations to compare the efficiency of pneumatic fracturing on the aspect of the site remediation and the porosity improvement at several hypothetic unsaturated zones composed of four typical soil types. According to the simulation results, it is found that the zone with fine grains soil such as clay and silt shows better efficiency than the zone composed of coarse grains in terms of air flow and porosity enhancements. The results imply that pneumatic fracturing may improve the efficiency of site reclamation by jointly or independently applied to the many contaminated sites in Korea.

• Journal of the Korea Organic Resources Recycling Association
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• v.21 no.3
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• pp.53-63
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• 2013

It is well known that problem for contaminated soil with heavy metals is mainly produced from agricultural land around abandoned metal mine and the cost to solve them is much higher than those of water and air pollution in addition, it takes much more time to clarify the contaminated soil. Until now, economical and practical many techniques to remediate contaminated soils with heavy metals have been developed and proposed. Therefore, in this study, characteristic, merit and weakness for various techniques which are developing and commercializing recently in domestic/foreign country will be reviewed.

• Journal of Korean Society on Water Environment
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• v.24 no.1
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• pp.19-29
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• 2008

Hot air sparging is a groundwater remediation technique, in which organic contaminants volatilized into hot air from the saturated to vadose zone. In the laboratory diesel (10,000 mg TPH/kg) was spiked in contaminated saturated aquifer soil. The hot air ($34.9{\pm}2.7^{\circ}C$) was injected in intermittent (Q=1,500 mL/min, 10 minute injection and 10 minute idle) modes. We performed microcosm tests using the groundwater samples to assess TPH reductive remediation activity. For Terminal-Restriction Fragment Length Polymorphism (T-RFLP) analysis of eubacterial communities in sludge of wastewater treatment plants and soil of experiment site, the 16S rDNA was amplified by Polymerase Chain Reaction (PCR) from the sludge and the soil. The obtained 16S rDNA fragments were digested with Msp I and separated by electrophoresis gel. We found various sequence types for hot air sparging experiment with sludge soil samples that were closely related to Bacillus (149 bp, Firmicutes), Methlobacterium (149 bp, Euryarchaeotes), Pseudomonas (492 bp, ${\gamma}$-Proteobacteria), etc., in the clone library. In this study we find that TPH-water was reduced to 78.9% of the initial value in this experiment aquifer. The results of the present study suggests that T-RFLP method may be applied as a useful tool for the monitoring in the TPH contaminated soil fate of microorganisms in natural microbial community.

• Journal of Environmental Science International
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• v.20 no.10
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• pp.1329-1336
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• 2011

The objectives of this study are to examine the processing of oils contamination soil by means of using a micronano-bubble soil washing system, to investigate the various factors such as washing periods, the amount of micro-nano bubbles generated depending on the quantity of acid injection and quantity of air injection, to examine the features involved in the elimination of total petroleum hydrocarbons (TPHs) contained in the soil, and thus to evaluate the possibility of practical application on the field for the economic feasibility. The oils contaminated soil used in this study was collected from the 0~15 cm surface layer of an automobile junkyard located in U City. The collected soil was air-dried for 24 hours, and then the large particles and other substances contained in the soil were eliminated and filtered through sieve No.10 (2 mm) to secure consistency in the samples. The TPH concentration of the contaminated soil was found to be 4,914~5,998 mg/kg. The micronano-bubble soil washing system consists of the reactor, the flow equalization tank, the micronano- bubble generator, the pump and the strainer, and was manufactured with stainless material for withstanding acidic phase. When the injected air flow rate was fixed at 2 L/min, for each hydrogen peroxide concentrations (5, 10, 15%) the removal percents for TPH within the contaminated soil with retention times of 30 minutes were respectively identified as 4,931 mg/kg (18.9%), 4,678 mg/kg (18.9%) and, 4,513 mg/kg (17.7%). And when the injected air flow rate was fixed at 2 L/min, for each hydrogen peroxide concentrations (5, 10, 15%) the removal percents for TPH within the contaminated soil with retention times of 120 minutes were respectively identified as4,256 mg/kg (22.3%), 4,621 mg/kg (19.7%) and 4,268 mg/kg (25.9%).

• Journal of Environmental Impact Assessment
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• v.14 no.4
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• pp.147-155
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• 2005

This study was designed to investigate the effect of plant as a botanical air purification on the indoor pollution by formaldehyde. Three indoor plants such as Dracaena marhginata, Spathiphyllum and Dracaena reflexa, were placed in the artificially contaminated reactor under laboratory condition. Both plant and soil effects on removal of formaldehyde from contaminated indoor air were observed. Reductions in the formaldehyde levels appeared to have been associated with soil medium factors as well as plant factors. The effect of soil on formaldehyde reduction was high in the early stage of the experiment and the results suggest that sorption could be more important factor than microbial degradation in the initial dissipation of contaminants in the soil. It was suggested that the effect of plant on formaldehyde reduction might be related to the plant species, total leaf surface area of plant, degree of contribution of soil medium, and exposed concentration level. The results of this study showed that air purification using plants is an effective means of reduction on indoor formaldehyde level, though, utilization of soil media with high sorption capacity and/or supplementary purifying aids were also suggested when the source is continuous or exposed concentration level is high.

• Journal of Korean Society on Water Environment
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• v.23 no.5
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• pp.665-675
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• 2007

In-situ Air Sparging (IAS, AS) is a remediation technique in which organic contaminants are volatilized from saturated zone to unsaturated layer. This study focuses on the removal and interaction of Volatile Organic Compounds (VOCs) and $CO_2$, and Total Petroleum Hydrocarbon (TPH) in saturated and unsaturated, and air space zone on the unsaturated soil surface. Soil sparging temperature of hot air has risen to $34.9{\pm}2.7^{\circ}C$ from $23.0{\pm}1.9^{\circ}C$ for 36 days. At the diffusing point, fluid TPH concentrations were reduced to 78.7% of the initial concentration in saturated zone when hot air was sparged. The TPH concentrations were decreased to 66.1% for room temperature air sparging. The amount of VOCs for hot air sparging system, in air space, was approximately 26% larger than constant air sparging system. The amount of $CO_2$ was 4,555 mg (in unsaturated zone) and 4,419 mg (in air space) when hot air was sparged was 3,015 mg (in unsaturated zone) and 3,634 mg (in air space) for room air temperature in the $CO_2$ amount. The removals of VOCs and biodegradable $CO_2$ through the hot air sparging system (modified SVE) were more effective than the room temperature air sparging. The regression equation were $Y=976.4e^{-0.015{\cdot}X}$, $R^2=0.98$ (hot air sparging) and $Y=1055e^{-0.028{\cdot}X}$, $R^2=0.90$ (room temperaure air sparging). Estimated remediation time was approximately 500 days, if final saturated soil TPH concentration was set to 1.2 mg/L application of tail effect.

• Restorative Dentistry and Endodontics
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• v.25 no.4
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• pp.575-586
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• 2000

In this study, adaptation of compomer to saliva contaminated dentin was evaluated with scanning electron microscope(SEM) and confocal laser scanning microscope(CLSM). For the SEM study, the occulusal surfaces of thirty two molar teeth were grounded to exposure dentin surfaces. The specimen were randomly assigned to control and three experimental groups with four samples in each group. In control group, Dyract and F-2000 compomer were bonded on the specimens according to the manufactures direction. Experimental groups were subdivided into three groups. They were contaminated with saliva on dentin surfaces ; Experimental group 1 : Saliva was dried with compressed air. Experimental group 2 : Saliva was rinsed with air-water spray and dried. Experimental group 3 : After polymerization of an adhesive, they were contaminated with saliva, and then saliva was rinsed with air-water spray and dried. Dyract and F-2000 compomer were bonded on saliva-treated dentin surfaces. The interfaces between dentin and compomer were observed with SEM. For the CLSM study, Class V cavities were prepared in buccal and ligual surfacess of thirty two molars. The specimens were divided into control and experimental groups. Class V cavities in experimental group were contaminated with saliva and those surfaces in each experimental groups received the same treatments as for the SEM study. Cavities were applied Prime & Bond 2.1 and F-2000 compomer primer/adhesive that were mixed with fluorescein, and then were filled with Dyract and F-2000 compomer. Specimens were embedded in transparent acrylic resin and sectioned buccolingual1y with diamond wheel saw, and then mounted on cover slide for CLSM study. The interface between cavity and compomer was observed by fluoresence imaging with a CLSM. The results were as follows : 1. In SEM exammination of Dyract group, control group, experimental group 2, 3 showed close adaptation to dentin and hybrid layer of $3{\sim}4{\mu}m$ diameter. Interfacial gap between compomer and dentin in experimental group 1 was wider than in control group. 2. In SEM examination of F-2000 group, adaptation to dentin of control group was closer than Dytact control group, but hybrid-like layer was not observed. Interfacial gap between compomer and dentin in experimental group 1 was wider than in Dyract experimental group 1. 3. In dissolution specimens of Dyract and F-2000 group, resin tags penetrated through dentinal tubules in control group and experimental group 1 and 3, but the penetration of resin tag was irregular and partial in experimental group 1. 4. In CLSM exammination of Dyract and F-2000 group, adhesive patterns of control and experimental groups showed same as in SEM. This result suggests the treatment methods, rinsing & drying, repeating all adhesive procedures, will produce good effect on adaptation of compomer to dentin if the dentin surface or polymerized adhesive is contaminated by saliva.

• Journal of Environmental Science International
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• v.13 no.12
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• pp.1059-1065
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• 2004

Bio sparging experiments were conducted in a laboratory column to investigate the potential removal of diesel contaminated groundwater. The objectives in this study were (a) to determine the extent of diesel degradation in laboratory columns under supplement of nutrient; (b) to determine the effect of variation of air flow in the removal of diesel and (c) to evaluate the potential enhancement of diesel degradation as a function of temperature. Our results showed that the nutrient supplement and higher air flow greatly enhanced diesel degradation. However, the variation of water temperature examined slightly increased degradation rate of diesel fuel.

• Journal of Soil and Groundwater Environment
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• v.11 no.4
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• pp.10-17
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• 2006

Laboratory-scale two-dimensional aquifer physical model studies were conducted to assess the effect of air injection rate and air injection pattern on the removal of disel contaminated soil and groundwater by air/bio-sparging. The experimental results were represented that the optimal conditions in this experiment were as air injection rate of 1,000 ml/min and pulsed air injection pattern(15 min on/off). The results of the TPH reduction, DO consumption and $CO_2$ production indicate the effective biodegradation evidence of diesel. Based on our results, The minimal $O_2$ supply and pulsed air injection pattern could effectively enhance the diesel removal and the pulsing air injection had effect on oxygenation in this system. Thus, the cost of operating air/bio-sparging system will be reduced if optimal air injection rate and pulsed air injection pattern are applied to remediate contaminants.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1998.11a
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• pp.232-235
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• 1998

Air sparging system is a kind of in-situ bioremediation method in the contaminated ground water. When Air sparging, the both of water circulation and oxygen transfer happend in the same time. The hydraulic differential head is zero at the middle height of well, is negative below the height and is possitive above the height. Hydroraulic head gradient is proportioned to air superficial velocity in the well. But over 24m/min of the superficial velocity, the hydraulic head gradient increase little.