• Journal of the Korean Society of Groundwater Environment
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• v.2 no.1
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• pp.22-29
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• 1995

Mobile bacterial particles can act as carriers and enhance the transport of hydrophobic contaminants in ground water by reducing retardation effects. Because of their colloidal size and favorable surface conditions, bacteria can act as efficient contaminant carriers. When such carriers exist in a porous medium, the system can be thought of as three phases: an aqueous phase, a carrier phase, and a stationary solid matrix phase. Contaminant can be present in either or all of these phases. In this study, a mathematical model based on mass balances is developed to describe the transport and fate of biodegradable contaminant in a porous medium. Bacterial mass transfer mechanism between aqueous and solid matrix phases, and contaminant mass transfer between aqueous and bacterial phases are represented by kinetic models. Governing equations are non-dimensionalized and solved to analyze the bacteria facilitated contaminant transport. The numerical results of the facilitation effect match favorably with experimental data reported in the literature. Results show that the contaminant transport can be described by local equilibrium assumption when Damkohler numbers are larger than 10. Significant sensitivities to model parameters, particularly bacterial growth rate and influent bacterial concentration, were discovered.

• Membrane Journal
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• v.16 no.1
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• pp.59-67
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• 2006

Biodegradable amphiphilic polymer was synthesized for removing hydrophobic pollutants(phenol, 4-nitrophenol, benzene, and toluene) and metal ions ($Cs^{+},\;Mg^{2+},\;Cu^{2+},\;Ni^{2+}$, and $Cr^{3}$). The methoxy poly(ethylene glycol)s with different molecular weights (1,100 and 5,000) were used as a hydrophilic segment. The rejection ratio improved in the relatively high molecular weight of MPEG. The rejection ratio of biodegradable nanoparticles without pollutants was over 98%. In removal of hydrophobic pollutants, the rejection ratio increased with the hydrophobic properties. The electron valence affects the rejection ratio of metal ions, indicating rejection ratio was ordered as $3^{+}>2^{+}>1^{+}$.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2006.04a
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• pp.162-165
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• 2006

유해성 유기물질로 오염된 토양의 복원을 위한 토양세척공정에서 계면활성제를 선택적으로 재이용하기 위해 활성탄을 이용한 흡착 칼럼의 성능을 평가하였다. 계면활성제로는 Triton X-100을 소수성 유해 유기물질로는 다환방향족 탄화수소의 하나인 phenanthrene를 사용하여 그 성능을 평가하였다. 계면활성제의 흡착은 phenartthrene에 비해 빠른 흡착 특성을 보였으며 phenanthrene은 계면활성제의 포화흡착상태에서도 지속적으로 흡착이 이루어졌다. 이는 계면활성제의 흡착이 종료된 이후에도 유해성 유기물질의 지속적인 흡착을 기대할 수 있어 계면활성제의 지속적인 재이용과 활성탄 사용시간의 증대를 가져올 수 있음을 의미한다. 이와 같은 활성탄 칼럼에서의 유해성 유기물질의 우수한 선택적 흡착 결과는 기본적으로 소수성 정도의 차이와 size exclusion에 의한 기작뿐만 아니라 활성탄에 흡착된 계면활성제에 의한 다환방향족 탄화수소의 추가적인 흡착이 일어나 전체적인 성능이 향상되는 것에 기인한다.

• Journal of Korea Soil Environment Society
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• v.1 no.2
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• pp.61-72
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• 1996

A series of batch and lab-scale continuous tests were conducted to optimize the design parameters for the full-scale in-situ soil flushing experiments. The cleaning abilities of the surfactant solutions of Tween 80, Triton X-100 and SDS were compared for the soil artificially contaminated by hydrophobic organic contaminants: n-dodecane, naphthalene and anthracene. Tween 80 and Triton X-100 were shown to be efficient for n-dodecane. SDS and Tween 80 were shown to be efficient for naphthalene and anthracene. At the end of each column test, the sorbed amount of surfactant to soil was also measured. Tween 80 was found to be the least adsorbed surfactant to soil. The flushing ability at flowrate of 7 ml/min, was hampered comparing to flowrate of 3 and 5 ml/min. Initial pH of the soil did not significantly affect the flushing efficiencies. Tween 80 was determined as the most harmless surfactant for the Gram(+) and Gram(-) bacteria.

• Journal of the Korean Geosynthetics Society
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• v.14 no.1
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• pp.23-32
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• 2015

This paper describes a flow experiment and characteristics of heavy metals based on microfluidics, in order to improve the prefabricated vertical drain system that is possible pollutants removal and soil improvement in soft ground polluted with various pollutants, simultaneously. The result showed that the surface with hydrophobic condition affected large effect on flow velocity pollutants, and pH condition was also influence factor for change of flow velocity. Especially, the flow velocity of lead has risen slightly, when pH was close to basicity in complex heavy metal. This means that lead pollutant can reduce a hydrophobic characteristic in comparison with a copper pollutant.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.3
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• pp.152-158
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• 2015

This paper investigated the membrane fouling potential at the state of passive adsorption which is no permeation with the test modules on COD (Chemical oxygen demand) loading rates, examined the recovery rate and resistance on membrane fouling by three cleaning manners of hydrophobic membrane in a bioreactor. The results showed that high COD loading led to the increase of extra-cellular polymeric substances and filtration resistance. The permeability resistance from 1st day to 63rd day was getting increased, however, the value of permeability resistance after 63th day during the operation period was almost same level at three COD loading rates, it was due that the biomass adhesion on membrane surface at the state of passive adsorption reached to the critical state. Also, the final recovery rates after three cleaning manners were 78%, 72% and 69% at the COD loading concentrations of 250 mg/L, 500 mg/L and 750 mg/L respectively, and then recovery rate by physical cleaning at Run 2 and Run 3 was decreased after 40th day, it proved that biomass cake, which is not easily removed, was formed on the membrane surface because of high COD loading rate and EPS concentration.

• Journal of Korea Soil Environment Society
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• v.2 no.2
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• pp.9-24
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• 1997

Surfactant-aided in situ soil flushing has been proposed as an alternative for the expensive and time consuming 'pump and treat' technology in remediation of contaminated soil and groundwater Injected surfactants can effectively solubilize contaminants sorbed to the soil matrix or nonaqueous phase liquids(NAPLs) in residual saturation. The contaminants solubilized in groundwater are recovered and treated further. The theoretical background of the technology and the results of the field operations, mostly in the US. were summarized. In addition, the factors crucial to the successful application of the technology were discussed. Cost analyses and technical limitations in current applications were also discussed. In conclusion, it is likely that in situ surfactant flushing become a viable option for soil remediation in limited cases. Currently, further advances with respect to operation cost and to treatment efficiency are required for more extensive application of the technology. However, the current trends in soil remediation, specially the growing emphasis on risk based corrective action and natural attenuation, will increase the competitiveness of the technology. For example, removal of easily washable contaminants by short term soil flushing followed by long term monitoring and natural attenuation can greatly reduce the operation cost and time.

• Journal of the Korean GEO-environmental Society
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• v.4 no.2
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• pp.39-46
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• 2003

An immobilization zone can be constructed by modifying soils in the vadose zone with surfactants, which can be used to promote retardation of organic contaminants in the subsurface. Column experiments were conducted to investigate the behavior of surfactants and organic contaminants in unsaturated and saturated conditions with different water contents (25%, 50%, 75%, 100%). Transport and sorption of surfactant (dialkylated disulfonated diphenyl oxide) in the columns containing aluminum oxide was similar under the conditions at different water contents. However, transport of a model organic compound (naphthalene) was retarded as the water content decreased by enhanced partitioning of the compound into the surfactants that were sorbed on the aluminum oxide. This suggests that the immobilization method could well be applied to vadose zone as well as to saturated zone.

• Membrane Journal
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• v.24 no.6
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• pp.431-437
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• 2014

To overcome the flux reduction due to the fouling by adsorption of foulants onto the porous hydrophobic polyethylene membrane surface, the oxyflorination was introduced to hydrophilize the hydrophobic membranes. After the hydrophilization through oxyfluorination, the contact angle decreased from $93^{\circ}$ to $50^{\circ}$ while the water flux increased to 60%. It was considered that for the model foulants dissolved in water, such as albumin (form bovine serum, BSA), humic acid sodium salt (HA), and alginic acid sodium salt (SA), the flux was enhanced since the adsorbed foulants decreased by the oxyfluorination. Particularly, it was obtained that the water flux was over twice more than the untreated polyethylene membrane in case of SA foulant.

• Korean Journal of Materials Research
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• v.6 no.11
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• pp.1127-1135
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• 1996

반도체 소자가 고집적화 됨에 따라 단위공정의 수가 증가하게 되었고 동시에 실리콘 기판의 오염에 대한 문제가 증가하였다. 실리콘 기판의 주 오염물로는 유기물, 파티클, 금속분순물 등이 있으며 특히, Cu와 Fe과 같은 금속불순물은 이온주입 공정, reactive ion etching, photoresist ashing과 같은 실 공정 중에 1011-1013atoms/㎤정도로 오염이 되고 있다. 그러나 금속불순물 중 Cu와 같은 전기음성도가 실리콘 보다 큰 오염물질은 일반적인 습석세정방법으로는 제거하기 힘들다. 따라서 본 연구에서는 Cu와 Fe과 같은 금속불순물을 제거할 목적을 건식과 습식 세정방법을 혼합한 UV/ozone과 HF세정을 제안하여 실시하였다. CuCI2와 FeCI2 표준용액으로 실리콘 기판을 인위적 오염한 후 split 1(HF-only), split 2 (UV/ozone+HF), split 3 (UV/ozone + HF 2번 반복), split 4(UV/ozone-HF 3번 반복)를 실시하였고 TXRF(Total Reflection X-Ray Fluorescence)와 AFM(Atomic Force Microscope)으로 금속불순물 제거량과 표면거칠기를 각각 측정하였다. 또한 contact angle 측정으로 세정에 따른 표면상태도 측정하였다. TXRF 측정결과 split 4가 가장 적은 양의 금속불순물 잔류량을 보였으며 AFM 분석을 통한 표면거칠기도 가장 작은 RMS 값을 나타내었다. Contact angle 측정 결과 UV/ozone 처리는 친수성 표면을 형성하였고 HF처리는 소수성 표면을 형성하였다.