• Economic and Environmental Geology
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• v.46 no.6
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• pp.509-520
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• 2013

In this study, heavy metals are removed by soil washing from soils contaminated with Cu, Zn, and Pb, whose maximum concentrations are up to 3350, 1220, and 2240 mg/kg, respectively. Through various soil washing experiments, the optimum conditions, including type and concentration of washing reagent, washing time, mixing ratio of soil and washing reagent, and stirring speed, are derived for effective removal of the heavy metals. It is found that the most effective washing reagent and its concentration are hydrochloric acid and 50 mM, respectively. The most suitable washing time is 30 minutes and the optimal mixing ratio of soil and washing reagent is 1:30 (g/mL). The removal efficiency, on the other hand, is not affected by stirring speed. The removal efficiencies of the heavy metals decrease when washing reagent is reused. Furthermore, the heavy metals are readsorbed onto soil in case of consecutive reuse of washing reagent.

• Journal of Korea Soil Environment Society
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• v.2 no.2
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• pp.95-103
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• 1997

Solvent extraction using aqueous solutions is presumed as one of the most effective methods applicable to in situ conditions without excavation of contaminated soils. Laboratory permeameter soil flushing test is performed to describe the process of solvent extraction of contaminants absorbed on soil particles. When the permeameter tests conducted, diffusion of contaminants through the permeameter flexible-wall was considered for adjusting the remediation percentage. Input and output balance for concentration was well matched in the permeameter tests. Nitrobenzene diffused so excessively (approximately 75%) that it was not suitable for the permeameter desorption tests. No biodegradation was detected in the soil samples.

• Clean Technology
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• v.26 no.1
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• pp.13-21
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• 2020

Air pollutants in a subway are complexly caused by outdoor factors such as ventilating opening and indoor factors such as the movement of passengers on the subway. According to recent research results, most of the air pollutants generated in subway tunnels and stations are caused by indoor variables such as train movement. To control air pollutants such as particulate matter (PM), a prevention facility such as the electrostatic precipitator (EP) or bag filter collector was required in a subway station. In particular, the PM removed by the EP must be kept clean continuously to manage PM effectively. Therefore, a nano-bubbling washing system was developed in this study to clean a contaminated collecting plate in an EP at the main subway tunnel in Seoul. Removal efficiency compared with normal water and nano-bubbling water was likewise studied. As a result, the washing efficiency of collective PM increased in accordance with the increasing of injection pressure, with nano bubbling washing being 130.8% higher than tap water. According to increase in washing times, the maximum washing efficiency was 143.1% higher than tap water, but suitable washing times were less than 3 times. According to the results of the washing efficiency by variation of residence time, it was confirmed that the maximum residence time of nano-bubble water was maintained within 5 minutes.

• The Korean Nurse
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• v.21 no.5 s.118
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• pp.76-79
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• 1982

• Clean Technology
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• v.18 no.4
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• pp.390-397
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• 2012

Removal characteristics of lead-contaminated soil at the military shooting range located in the Changwon city were studied experimentally using soil washing process. As a washing solution, hydrogen chloride (HCl) concentrations of 0.001, 0.01, 0.1 and 0.2 N were used, and soil : solution ratios were 1 : 2, 1 : 3, 1 : 4, and 1 : 5. Particle diameter of contaminated soil of 4-0.075 mm, and washing period of 5, 10, 15, 20, 30, 60, and 120 min were used as operating parameters. The optimum concentration of HCl solution was 0.1 N (56.3% of Pb removal efficiency) with 15 minutes operation period in views of economics, and the optimum soil : solution ratio was determined as 1 g : 3 mL for 69.7% of Pb removal efficiency with 0.1 N HCl and 15 minutes washing period. As washing period increased, removal efficiency was increased until 20 min of the removal efficiency of 75.3%, and then almost stable. Pb removal efficiency in soil particle diameters of 0.075 mm or more was ranged from 77.0% to 82.0%, but it was decreased to 52.8% in diameter of less than 0.075 mm. Therefore, the optimum cut-off size of the soil particle diameter was found less than 0.075 mm. Combined HCl solution and ultrasonic washing method showed better removal efficiency compared to only water or HCl washing method for particle sizes above 0.075 mm.

• Journal of Korea Soil Environment Society
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• v.2 no.2
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• pp.53-60
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• 1997

A series of batch and lab-scale pilot tests were conducted to optimize the design parameters for the application of soil washing techniques to the soil contaminated by heavy metals. Cu, Pb, and Zn were selected as target heavy metals. The concentrations of Cu, Pb, and Zn were 500mg/kg dry soil, 1, 000mg/kg dry soil, and 500mg/kg dry soil, respectively. Citric acid and oxalic acid were used for the extractants. In the batch tests, the extraction efficiencies for Cu, Pb, and Zn were 79%, 72%, 72%, respectively. The proper extractant concentration and dilution ratio(weight/volume) for Cu and Pb were turned to be citric acid 50mM and 1:5, respectively. The extraction efficiencies were enhanced with the addition of 1~2% OA-5 or SDS. From pilot scale tests for Pb, first stage and second stage of soil washing resulted in the extraction efficiency of 59% and 78%, respectively.

• The Journal of Engineering Geology
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• v.22 no.3
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• pp.253-262
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• 2012

With the aim of remediating soils contaminated by heavy metals and oil, experimental research was conducted to evaluate the optimal design factors for remediation in terms of efficient soil washing methods and processes. The experiments employed absorptiometric analysis and gas chromatography methods to reduce the concentration of heavy metals such as cooper (Cu), lead (Pb), and zinc (Zn), and total petroleum hydrocarbons (TPH) in contaminated soils. The experimental processes consisted of deciding on the washing solution, washing time, and dilution ratio for contaminated soils. A dissolution analysis of heavy metals was then performed by the addition of surfactant, based on the results of the decision experiments, and the injection processes of microbes and hydrogen peroxide were selected. The experimental results revealed that reduction effects in contaminated soils under the experimental conditions were most efficient with hydrochloric acid 0.1 mole, washing time 1 hour, and dilution ratio 1:3, individually. Additional reduction effects for heavy metals and TPH were found with the addition of a washing solution of 1% of surfactant. The addition of microbes and hydrogen peroxide caused a reduction in TPH concentration.

• Korean Chemical Engineering Research
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• v.45 no.5
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• pp.500-505
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• 2007

The objectives of this research were to (1) identify the membrane fouling potential due to different fractions of NOM (2) correlate the physicochemical properties of NOM and membranes with the adsorption of humic substances on membrane (4) find out the effect of membrane physical and chemical washing according to membrane material. The static adsorption test and adsorption test showed that hydrophobic organics adsorbed much more quickly than hydrophilic organics. In case of the effect of membrane properties on the adsorption of organic fractions, the adsorption rate ratio(a) of hydrophobic membrane (0.016, 0.077) was greater than that of hydrophilic membrane (0.010, 0.033) regardless of the kind of organic fractions. This suggests that the UF membrane fouling were occurred mainly by internal pore size decreasing due to adsorption of organic into pore surface for hydrophobic membrane, and by sieving of organics and forming a gel layer on the membrane surface for hydrophilic membrane. In conclusion, the decrease in the pore volume, which was caused by the organic adsorption into the internal pore, was greater with the hydrophobic membrane than with the hydrophilic membrane. In case of the effect of membrane properties on permeate flux, the rate of flux decline for the hydrophobic membrane was significantly greater than that for the hydrophilic membrane.

• Applied Chemistry for Engineering
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• v.31 no.2
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• pp.193-199
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• 2020

The effects of the composition of the dishwashing detergent on interfaces of the oil (O) and the aqueous (W) solution in addition to the cleaning effects of interfacial properties were investigated. Also, the cleaning power of the oil contaminated on the surface of the dish according to each composition and the residuals of the contaminants and the cleaning agent after the washing rinses were evaluated. The removal of contaminated oil on the solid (S) surface in the composition of the cleaning agents used in this study was strongly related to the interfacial properties between the W/O/S, and was particularly dependent on the forward and backward dynamic contact angles. When both contact angles were low at the same time, the permeability of the cleaning solution was so high that the contaminated oil showed a high removal effect. The smaller the interfacial tension of O/W was, the better emulsification of the contaminated oil, the higher the interfacial tension, and the poorer emulsification were achieved. However, the emulsification effect did not significantly affect the cleaning power. In particular, in the case of the cleaner having low interfacial tension, the cleaning material remained on the surface of the solid after washing.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.1129-1133
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• 2010

본 연구에서는 수질오염총량제와 정책제안의 원활하고 합리적인 추진을 위해 토지피복분류체계의 대분류중 초지에 해당하고 중분류 중 골프장에 해당하는 지점을 선정하여 강우에 의해 발생하는 비점오염물질의 유출특성을 분석하였다. 연구기간 동안 총 27번의 강우사상으로 인해 발생하는 강우유출수에 대하여 유량과 수질농도를 측정하였다. 유량측정은 웨어를 통한 수위를 측정하여 유량으로 환산하였고, 수질항목은 $BOD_5$, $COD_{Mn}$, DOC, SS, T-N, T-P, $NH_3$-N, $NO_3$-N, $PO_4$-P 등 9개 항목을 분석하였다. 분석된 결과를 이용하여 골프장에서 발생하는 비점오염원의 초기세척효과 발생여부를 판단하기 위하여 누적오염부하량/누적유출량 그래프를 도식화하였다. 연구기간동안 발생한 5~82 mm의 강우로 인해 6.6~2,082 $m^3$의 유출이 발생하였다. 발생된 유출수의 농도는 $BOD_5$ 1.8~11.3 mg/L, $COD_{Mn}$ 19.2~51.4 mg/L, DOC 11.0~31.0 mg/L, SS 2.2~57.3 mg/L, T-N 1.545~16.098, T-P 0.230~4.528 mg/L, $NH_3$-N 0.076~5.285 mg/L, $NO_3$-N 0.122~2.905 mg/L, $PO_4$-P 0.005~2.631 mg/L로 나타났다. 초기유출수의 세척효과는 27번의 강우사상동안 SS 항목의 경우 17번, $NO_3$-N 11번, $NH_3$-N 4번 등이 발생하였다. 초기세척효과가 발생한 강우사상은 초기의 오염원 농도가 중 후반 농도보다 농도가 높음을 의미하므로, 골프장에서 발생하는 강우유출수는 초기에 발생하는 오염원에 초점을 두고 처리방안을 모색해야 할 것으로 판단된다. 또한 SS와 질소계열의 농도가 높은 것은 골프장의 잔디관리를 위한 농약이나 제초제 등의 사용과 토양유실이 원인인 것으로 판단되며, 이를 저감하기 위한 적절한 사용방안과 저감대책이 필요할 것으로 판단된다.