• Journal of Environmental Science International
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• v.26 no.1
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• pp.23-28
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• 2017

This study was aimed at determining the changes in heavy metal removal efficiency at different acid concentrations in a micro-nanobubble soil washing system and pickling process that is used to dispose of heavy metals. For this purpose, the initial and final heavy metal concentrations were measured to calculate the heavy metal removal efficiency 5, 10, 20, 30, 60, and 120 min into the experiment. Soil contaminated by heavy metals and extracted from 0~15 cm below the surface of a vehicle junkyard in the city of U was used in the experiment. The extracted soil was air-dried for 24 h, after which a No. 10 (2 mm) was used as a filter to remove large particles and other substances from the soil as well as to even out the samples. As for the operating conditions, the air inflow rate in the micro-nano bubble soil washing system was fixed at 2 L/min,; with the concentration of hydrogen peroxide being adjusted to 5%, 10%, or 15%. The treatment lasted 120 min. The results showed that when the concentration of hydrogen peroxide was 5%, the efficiency of Zn removal was 27.4%, whereas those of Ni and Pb were 28.7% and 22.8%, respectively. When the concentration of hydrogen peroxide was 10%, the efficiency of Zn removal was 38.7%, whereas those of Ni and Pb were 42.6% and 28.6%, respectively. When the concentration of hydrogen peroxide was 15%, the efficiency of Zn removal was 49.7%, whereas those of Ni and Pb were 57.1% and 42.6%, respectively. Therefore, the efficiency of removal of all three heavy metals was the highest when the hydrogen peroxide concentration was 15%.

• Korean Journal of Environmental Agriculture
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• v.16 no.3
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• pp.255-258
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• 1997

In order to determine the removal efficiency of pesticide residues on apples by ultrasonic cleaner, apples(Fuji var.) were artificially treated by dipping in water solution of fenitrothion EC, chlorpyrifos EC and phenthoate EC. The treated apples were washed by the ultrasonic cleaner with water, 30% ethanol solution or 0.2% detergent solution, respectively. The removal efficiency of fenitrothion, chlorpyrifos and phent-hoate by ultrasonicated washing in water for 0.5min. was 39.2%, 32.0% and 50.4%, respectively, but there was a tendency to decrease the removal efficiency of the pesticide residues as the duration of ultrasonicated washing period is increased. The maximum removal efficiency of the pesticide residues washed in the detergent solution was observed by ultrasonicated washing the samples for 5min. and it was recorded as 33.5% ; fenitrothion, 30.1% ; chlorpyrifos and 48.3% ; phenthoate, respectively. However it's appeared that the longer the ultrasonicated washing period in 30% ethanol solution the more pesticides from the apples were removed and the maximum removal efficiency of the pesticides was recorded as 66.2%(fenitrothion ; washed for 15min.), 41.7%(chlorpyrifos ; washed for 10min.), 74.2%(phenthoate ; washed for 10min.).

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.1
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• pp.41-47
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• 2018

Radioactive substances, especially $^{137}Cs$ discharged in the course of Nuclear Power Plant Accident or maintenance of power plants, cause contamination of the soil. For habitation of residents and reuse of industrial land, it is inevitably necessary to decontaminate the soil. This study examines a soil washing process that has actually been used for washing of radioactive-contaminated soil. The soil washing process uses a washing agent to weaken surface tension of the soil and cesium, separating cesium from the soil. In this study, in order to raise the efficiency of the process, a flocculating agent was added to the washing water to remove fine soil and cesium. The cesium concentrations before and after applying the flocculating agent to cesium solution were measured through ICP-OES. When using 0.1 g of J-AF flocculating agent in the experiment, the maximum Cs removal performance was approximately 88%; the minimum value was 67%. Species combinations between cesium and soil were predicted using Visual MINTEQ Code; the ability to reuse the washing water or not, and the removal rate of the fine soil, determined via measurement of the turbidity after applying the flocculating agent, were determined.

• Journal of Soil and Groundwater Environment
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• v.13 no.1
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• pp.32-42
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• 2008

A surfactant recovery and reuse process by selective adsorption with activated carbon was proposed to reduce surfactant cost in a soil washing process. Mathematical model simulation was performed for the whole process, which consists of soil washing, soil recovery, and soil re-washing. The optimal range of surfactant dosage was $6{\sim}10$-fold critical micelle concentration in soil. The efficiency of surfactant reuse process was decreased with increasing the dosage of activated carbon. Effectiveness factor for activated carbon significantly altered the efficiency of the reuse process unlike effectiveness factor for soil. Total requirement of surfactant was reduced to 20-30% with the reuse process compared to the conventional soil washing process. The contamination of wastewater after soil washing was reduced with the reuse process. This mathematical model can be used to estimate performance of the whole process of soil washing including surfactant recovery and to obtain optimal ranges of operating conditions without extra labor-intensive experimental works.

• Korean Chemical Engineering Research
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• v.51 no.6
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• pp.745-754
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• 2013

This study evaluated the optimal soil washing conditions for toxic metals considering the removal efficiency of toxic metals from contaminated soils as well as from soil washing effluents. In the contaminated soils, As was the major contaminant and extracted by sodium hydroxide solution better than by sulfuric acid. However, in the case of the treatment of soil washing effluents, sodium hydroxide was less effective extractant because soil organic matter extracted by sodium hydroxide prevented the solid-liquid phase separation and toxic metal removal. In the treatment of soil washing effluents with sulfuric acid, toxic metals in the effluents were mostly precipitated at the pH above 6.5. In addition, granular ferric oxide (GFO) as an adsorbent enhanced the removal of As and Pb indicating that toxic metals in the washing effluents can be removed almost completely by the use of combined adsorption-neutralization process. This study suggests that soil washing techniques for toxic metals should be optimized based on the physical and chemical properties of the contaminated soils, the nature of chemical extractant, and the removal efficiency and effectiveness of toxic metals from the soils as well as soil washing effluents.

• Economic and Environmental Geology
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• v.53 no.4
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• pp.337-346
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• 2020

This study was carried out to evaluate the applicability of the soil washing process to remediation mercury-contaminated mine tailing or solid material (soil and sediments etc.) around abandoned mines. First, the physicochemical characteristics of mine tailing were analyzed through particle size analysis and sequential extraction. Secondly, laboratory scale washing experiments were performed using hydrochloric acid, nitric acid, potassium iodide and sodium thiosulfate. As a results of particle size analysis, mine tailing particle were concentrated below 40 mesh and the particle size below 200 mesh was the most analyzed. As a result of sequential extraction, elemental mercury fraction was analyzed as the highest with 69.12%, with strongly bound fraction 15.25% and residual and HgS fractions 11.97%, respectively. Laboratory scale washing experiments showed low applicability for nitric acid and sodium thiosulfate solutions. In case of hydrochloric acid solution, it was analyzed that mercury removal was possible at particle size of 200 mesh or more. Therefore, it is considered to be performed together with the physical sorting process. Potassium iodide solution was analyzed to have high washing efficiency at all concentrations and particle sizes. In particular, the mercury removal efficiency is high in the micro particles, and thus the applicability of the washing technology is the highest.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.597-604
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• 2003

In the soil washing process, the contaminants are usually removed by abrasion from soil particles using mechanical energy and water However, organic contaminants with low water solubility like polycyclic aromatic hydrocarbons (PAH) are remained on soil particles. Previous studies have shown that surfactant possessing amphipathic activity enhances the solubility of organic materials. For this reason solutions with surfactants have been used to improve removal of organic contaminants on soil washing process. But, in this manner, many problems were found like complete loss of surfactants and additional contamination by surfactant. The remediation method using microemulsion has been introduced to overcome these disadvantages. In this case, surfactants are recycled by phase separation of microemulsion after remediation. In microemulsion process, the surfactant will be recycled by phase separation of the microemulsion into a surfactant-rich aqueous phase and an oil phase after extraction. That is why remediation concept applying microemulsion as washing media has been Introduced. Suitable microemulsion have to be used in order to have the chance of refilling the soil after decontamination and to avoid any risk due to toxicity. The purpose of this research is to evaluate effect of microemulsion to remediation of contaminated soil. We performed test with various organic contaminants like Pyrene and BTEX, also compared efficiency of remediation in microemulsion process with soil washing

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1311-1314
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• 2005

Recently drum washing machines are required to improve not only functions, but also endurance security. The spider is one of the major parts in a drum washing machine as a power transmission device. It is needed estimating for fatigue life because it rotates at high velocity when the drum washing machine works. In this study, we tried to estimate fatigue life of the Spider with CAE and verified the accuracy by comparing the CAE results with the experimental results. The estimation method of fatigue life for the spider with CAE will be applied to raise the efficiency of time and money in the design process of a new drum washing machine.

• Journal of Korea Soil Environment Society
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• v.3 no.3
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• pp.109-116
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• 1998

Treatability tests of a soil washing device were performed for the remediation of eil-contaminated soil. The contaminant-containing soil with water was first fed into a oc-current screw conveyor and then into a counter-current washer. Surfactant was introduced into the washer and feeding soil was continuously separated on the basis of #40 mesh at the same time. A washing efficiency of 97.9% was achieved by the the soil washing device optimized.

• Journal of Embryo Transfer
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• v.7 no.1
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• pp.21-30
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• 1992

This study was aimed to develope the new method for bovine sperm capacitation through testing and combinating factors relating to sperm capacitation. For verifying the efficiency of this method on inducing capacitation, in vitro fertilization was carried out. The results obtained were as follows: When pHs of HBS /PR for sperm-washing were 5.99, 6.38, 6.78, 7.10, 7.40, 7.69, 8.15, 8.45 and 8.83, variances between light absorhance differences obtained from sperm pre-washing solution and post-washing solution(VADs) were 0.000, 0.001, -0.001, -0.005, -0.005, -0.021,-0.017,-0.016,and-0.036, respectively. There were significant decreases of VADs in pH 7.69 and pH 8.83. When sperm were firstly, secondly, and thirdly washed with HBS /PR, VADs were -0. 024, - 0.006, and - 0.004, respectively. There was significant decrease of VAD in 1st sperm-washing. When washed-sperm were secondly washed with HBS /PR supplemented with no (con-trol), heparin, CSA, PC12, and BSA, VADs were 0.009, -0.024, -0.008, -0.009, and 0.014, respectively. When the sperm were thirdly washed with HBS /PR with no(control), heparin, CSA, PC12 and BSA, VADs were 0.020, -0.007, 0.005, 0.006, and 0.019, respectively. Only heparin treatment showed the negative values of VADs in 2nd and 3rd sperm-washing. Of oocytes cultured with sperm which were repeatedly washed with heparin and high pH, 52% (57/110) were cleaved over 2 cell stage. However, percent of oocytes parthenogenetically divided was 5%(2 /42).