• Title/Summary/Keyword: Saturated Porous Media

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Evaluation of Bacterial Transport Models for Saturated Column Experiments

  • Ham, Young-Ju;Kim, Song-Bae;Kim, Min-Kyu;Park, Seong-Jik
    • Journal of The Korean Society of Agricultural Engineers
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    • v.48 no.7
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    • pp.55-63
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    • 2006
  • Bacterial transport models were evaluated in this study to determine the suitable model at describing bacterial transport in saturated column experiments. Four models used in the evaluation were: advective-dispersive equation (ADE) + equilibrium sorption/retardation (ER) + kinetic reversible sorption (KR) (Model I), ADE + two-site sorption (Model 2), ADE + ER + kinetic irreversible sorption (KI) (Model 3), ADE + KR + KI (Model 4). Firstly, analyses were performed with the first experimental data, showing that Model 4 is appropriate for describing bacterial transport. Even if Model 1 and 2 fit well to the observed data, they have a defect of not including the irreversible sorption, which is directly related to mass loss of bacteria. Model 3 can not properly describe the tailing observed in the data. However, further analysis with the second data indicates that Model 4 can not describe retardation of bacteria, even if the sorption-related parameters are varied. Therefore, Model 4 is modified by incorporating retardation factor into the model, resulting in the improved fitting to the data. It indicates that the transport model, into which retardation, kinetic reversible sorption, and kinetic irreversible sorption are incorporated, is suitable at describing bacterial transport in saturated column experiments. It is expected that the selected transport model could be applied to properly analyze the bacterial transport in saturated porous media.

Transport behavior of PVP (polyvinylpyrrolidone) - AgNPs in saturated packed column: Effect of ionic strength and HA (포화 컬럼실험에서 이온강도 변화 및 유기물질 출현에 의한 PVP로 코팅된 은나노 입자의 거동 연구)

  • Heo, Jiyong;Han, Jonghun;Her, Namguk
    • Journal of Korean Society of Water and Wastewater
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    • v.30 no.3
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    • pp.263-270
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    • 2016
  • Recent Engineered nanoparticles were increasingly exposed to environmental system with the wide application and production of nanomaterials, concerns are increasing about their environmental risk to soil and groundwater system. In order to assess the transport behavior of silver nanoparticles (AgNPs), a saturated packed column experiments were examined. Inductively coupled plasma-mass spectrometry and a DLS detector was used for concentration and size measurement of AgNPs. The column experiment results showed that solution chemistry had a considerable temporal deposition of AgNPs on the porous media of solid glass beads. In column experiment, comparable mobility improvement of AgNPs were observed by changing solution chemistry conditions from salts (in both NaCl and $CaCl_2$ solutions) to DI conditions, but in much lower ionic strength (IS) with $CaCl_2$. Additionally, the fitted parameters with two-site kinetic attachment model form the experimental breakthrough curves (BTCs) were associated that the retention rates of the AgNPs aggregates were enhanced with increasing IS under both NaCl and $CaCl_2$ solutions.

Seepage Flow Model for Analysis of the Flow Field within the Beach (해빈내의 흐름장 해석을 위한 침투류 모형)

  • 김규한;박창근;한상대;편종근
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.9 no.3
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    • pp.125-131
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    • 1997
  • In order to analyze the feasibility of the drain layer construction method, which is one of the beach protection methods, a hybrid model is constructed by combining the wave model and the seepage flow model. The used wave model is the analytic solution given by Shuto (1972). and the seepage flow model is used by Richards equation which governs the saturated-unsaturated flow in the porous media. It is concluded by the sensitivity analysis of the hybrid model that the most sensitive parameter in the flow field within the beach is the saturated hydraulic conductivity. The developed hybrid model will be efficiently used in the analysis of the parameter when the drain layers are constructed in the beach, if the field datas are obtained more.

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Organic Pollutant Transport in Unsaturated Porous Media by Atmospheric Breathing Processes( I ) - Partition Coefficient -

  • Ja-Kong;Lim, Jae-Shin;Do, Nam-Young
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 1996.11a
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    • pp.50-53
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    • 1996
  • This paper reports the experimental results for the determination of the overall partition coefficient of VOCs in unsaturated soil, A chromatographic method was used for the determination of gaseous partition coefficients to natural soil under various water content conditions. The equilibrium vapor pressure of water over saturated salt solution was used to fix the relative humidity of the air and control the water content of the soil systems. The transport behavior was studied for dichloromethane, trichloroethane and dichlorobenzene pollutants, with log octanol-water partition coefficients(log $K_{ow}$ ) which range from 1.25 to 3.39, or water to soil partitioning which varies by 135 times; water solubility constants which vary by 3 times; and vapor pressures which range from 1 to 362 torr. Water content of the soil had a pronounced effect on the effective partition coefficient(between gas and soil + water stationary phase) as well as on the effective dispersion coefficient.

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Numerical Analysis of Subsurface Flow in a Hillslope (자연 구릉지에서 지표하 흐름의 수치해석)

  • 최은호;남선우
    • Water for future
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    • v.24 no.1
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    • pp.109-117
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    • 1991
  • The governing equation of flow in porous media is developed on the bases of the continuity equation of fluid for transient flow through a saturated-unsaturated zone, and substitution of Darcy's law. The numerical solutions are obtained by finite element method based on the Galerkin principles weighted residuals. The analysis are carried out by using the unsteady storm data observed and rainfall intensities which are obtained by using the rainfall excess model in considering of the initial losses. The functional relationships between the hydraulic conductivity, capillary pressure head and volumetric water content are applied to the flow of water through unsaturated soil varied with changes of water content.

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A Particle Tracking Method for the Lagrangian-Eulerian Finite Element Method in 3-D Subsurface System (3차원 지표하 시스템에서 Lagrangian-Eulerian 유한요소법에 대한 입자추적 알고리즘)

  • Lee, Jae-Young;Kang, Mee-A
    • The Journal of Engineering Geology
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    • v.19 no.2
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    • pp.205-215
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    • 2009
  • The conventional numerical models to analyze flow in subsurface porous media under the transient state usually generate numerical oscillation and unstability due to local flux domain for critical cases such as infiltration into initially dry soil during rainfall period. In this case, it is required refined mesh and small time step, but it decrease efficiency of computation. In this study, numerical unstability in discontinuity domain is removed by applying particle tracking algorithm to simulate unsteady subsurface flow with inflow boundary condition. Finally the hybrid LE FEM improving numerical stability is proposed. The hypothetical domains with unsteady uniform and nonuniform flow field were used to demonstrated algorithm verification. In comparison with analytic solution, we obtained reasonable results and conducted simulation of hypothetical 3-D recharge/pumping area. The proposed algorithm can simulate saturated/unsaturated porous media with more practical problems and will greatly contribute to accuracy and stability of numerical computation.

Comparison of Kramers-Krönig Relation and High-Frequency Acoustic Measurements in Water-Saturated Glass Beads (다공성 입자 매질에서 고주파 영역 음향 측정 자료와 Kramers-Krönig 관계식의 비교)

  • Yang, Hae-Sang;Lee, Keun-Hwa;Seong, Woo-Jae
    • The Journal of the Acoustical Society of Korea
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    • v.30 no.7
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    • pp.402-407
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    • 2011
  • The necessary and sufficient condition for causality of a physical system can be expressed as Kramers-Kr$\ddot{o}$nig (K-K) relation. K-K relation for acoustic wave is a Hilbert transforms pair between dispersion equations of phase speed and attenuation. In this study, we quantitatively compare the acoustic measurements in water-saturated glass beads for the frequency ranges from 400 kHz to 1.1 MHz with the predictions of differential form of K-K relation obtained by Waters et al. For media with attenuation obeying an arbitrary frequency power law, acoustic measurements show good agreements with the predictions of Kramers-Kr$\ddot{o}$nig relation.

Water Holding Capacity and Hydraulic Conductivity According to Compaction and Saturation Degree for Perlite amended with Ground Coir (압밀과 포화수준에 따른 분쇄 Coir 혼합 펄라이트의 수분보유력과 수리전도도)

  • Kim, Gi-Rim;Woo, Hyun-Nyung;Kim, Hye-Jin;Park, Mi-Suk;Song, Jin-A;Song, Tae-Yong;Jang, Hyo-Ju;Chung, Doug-Young
    • Korean Journal of Soil Science and Fertilizer
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    • v.44 no.6
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    • pp.998-1003
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    • 2011
  • This investigation was performed to determine the hydraulic conductivity coefficient and water holding capacity for a specified compaction forces which are the amount of mechanical energy applied to the porous granule (PG) volume. Most current specifications of minerals and perlite as growth media require to be compacted to a specified density, which in general is equivalent to a certain percentage of laboratory compaction. The water holding capacity of the saturated PG was very large at potential above -1 bar compared with perlite, but very little water remained below this value. The water holding capacity and hydraulic conductivity characteristics of graded PG amended with the ground coir less than 2 mm in diameter were also determined from pressure outflow data. The saturated hydraulic conductivity of the saturated and compacted PG was slightly lower by more than one tenth order of magnitude at equal matric potentials of perlite, but when expressed on the basis of equal water deficits, the conductivity of PG was higher at all but the smallest deficits than those of perlite.

A Numerical Study on Spatial Behavior of Linear Absorbing Solute in Heterogeneous Porous Media (비균질 다공성 매질에서 선형 흡착 용질의 공간적 거동에 대한 수치적 연구)

  • Jeong, Woo Chang;Lee, Chi Hun;Song, Jai Woo
    • Journal of the Korean GEO-environmental Society
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    • v.4 no.3
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    • pp.79-88
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    • 2003
  • This paper presents a numerical study of the spatial behavior of a linear absorbing solute in a heterogeneous porous medium. The spatially correlated log-normal hydraulic conductivity field is generated in a given two-dimensional domain by using the geostatistical method (Turning Bands algorithm). The velocity vector field is calculated by applying the two-dimensional saturated groundwater flow equation to the Galerkin finite element method. The simulation of solute transport is carried out by using the random walk particle tracking model with CD(constant displacement) scheme in which the time interval is automatically adjusted. In this study, the spatial behavior of a solute is analyzed by the longitudinal center-of-mass displacement, longitudinal spatial spread moment and longitudinal plume skewness.

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Mobility of silver nanoparticles (AgNPs) and oxidative degradation of endocrine disrupting chemicals by saturated column experiments (포화컬럼실험에서 산화공정을 적용한 내분비계 장애물질의 제거 및 은나노물질의 거동 연구)

  • Kim, Yejin;Heo, Jiyong
    • Journal of Korean Society of Water and Wastewater
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    • v.32 no.6
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    • pp.499-505
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    • 2018
  • We applied column experiments to investigate the environmental fate and transport of silver nanoparticles(AgNPs) in fully saturated conditions of porous media. These column experiments were performed to emphasize oxidation method with $H_2O_2$ concentration and acidic conditions. The mobility of AgNPs was decreased with the increasing ionic strength that the surface charge of AgNPs(zeta potential) was neutralized with the presence of positive ions of $Na^+$. Additionally, it was also affected due to that not only more increased aggregated size of AgNPs and surface charge of quartz sand. The decreased breakthrough curves(BTCs) of bisphenol-A(BPA) and $17{\alpha}$-ethynylestradiol(EE2) were removed approximately 35.3 and 40%. This is due to that endocrine disrupting chemicals(EDCs) were removed with the release of $OH{\cdot}$ radicals by the fenton-like mechanisms from acidic and fenton-like reagent presenting. This results considered that higher input AgNPs with acidic conditions is proved to realistic in-situ oxidation method. Overall, it should be emphasized that a set of column experiments employed with adjusting pH and $H_2O_2$ concentration in proved to be effective method having potential ability of in-situ degradation for removing organic contaminants such as BPA and EE2.