• Title, Summary, Keyword: breakthrough curves

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Forecasting solute breakthrough curves through the unsaturated zone using artificial neural network

  • Yoon Hee-Sung;Hyun Yun-Jung;Lee Kang-Kun
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • pp.348-351
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    • 2005
  • In this study, solute breakthrough curves through the unsaturated zone were predicted using artificial neural network (ANN) by numerical tests and laboratory experiments. In the numerical tests, applicability of ANN model to prediction of breakthrough curves was evaluated using synthetic data generated by HYDRUS-2D. An appropriate strategy of ANN application and input data form were recommended. The ANN model was validated by laboratory experiments comparing with HYDRUS-2D simulations. The results show that the ANN model can be an effective method for forecasting solute breakthrough curves through the unsaturated zone when hydraulic data are available.

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The Effects of Resin Ratio and Bed Depth on the Performance of Mixed-bed Ion Exchange at Ultralow Solution

  • Yoon, Tae-Kyung;Lee, Gang-Choon;Noh, Byeong-Il
    • Journal of Environmental Science International
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    • v.18 no.6
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    • pp.595-601
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    • 2009
  • The effects of the cation-to-anion resin ratio and bed depth on ion exchange performance of mixed-bed were studied at ultralow solution concentration. Breakthrough curves were experimentally obtained for NaCI solution as functions of resin ratio and bed depth. The bed depth affects the pattern of the sodium breakthrough curve but not the chloride breakthrough curve in beds because of the selectivity difference. Resin selectivity determines the shape of breakthrough curves, Some sodium and chloride breakthrough curves crossed at a point as a function of resin ratio. The lower cation-to-anion resin ratio showed the higher effluent concentration or treated volume of the crossover point regardless of the total resin weight.

Adsorption Behaviors of Cesium and Strontium in Multicomponent System

  • Lee, Hoo-Kun;Park, Geun-Il;Ro, Sung-Gy;Park, Hyun-Soo
    • Proceedings of the Korean Nuclear Society Conference
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    • pp.274-279
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    • 1997
  • Breakthrough curves for separation of cesium and strontium binary components from aqueous solutions in fixed bed by chabazite and 13X were experimentally obtained and simulated the breakthrough curves for binary component adsorption. It is shown that agreements between model predictions and experimental data are relatively good although some deviations are observed. From engineering point of view, the simple model used here can be applied to simulate adsorption breakthrough curves satisfactorily.

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Determination of Adsorption Isotherm Parameters by Breakthrough Curves in Activated Carbon and Zeolite 13X Packed Bed (활성탄 및 제올라이트 13X를 충진한 흡착탑에서 파과곡선을 이용한 흡착등온식 상수의 결정)

  • Kang, Sung-Won;Min, Byung-Hoon;Suh, Sung-Sup
    • Applied Chemistry for Engineering
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    • v.16 no.1
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    • pp.131-138
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    • 2005
  • Freundlich isotherms and Toth isotherms were obtained for benzene adsorption on activated carbon and zeolite 13X in static experiments. Breakthrough curves of benzene were measured in adsorption bed packed with the same adsorbents. Relation between breakthrough times and partial pressure of benzene was analyzed and the Freundlich isotherm parameters were determined. Adsorption amount of benzene predicted by the analysis of breakthrough experimental results was relatively consistent with that predicted by the static experimental results. Dynamic experiments for activated carbon bed, where more symmetric breakthrough curves were obtained, produced smaller errors with zeolite bed.

Analysis of Solute Transport based on Electrical Resistance Measurements from Laboratory Column Tests (전기저항센서가 부착된 주상실험기에서 측정된 전기저항값을 이용한 용질의 이동해석)

  • Kim, Yong-Sung;Kim, Jae-Jin;Park, Junboum
    • Journal of The Korean Society of Civil Engineers
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    • v.28 no.4C
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    • pp.231-238
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    • 2008
  • A column testing device capable of measuring the electrical resistivity of soil at 3 different locations was developed to verify applicability of bulk electrical conductivity (BEC) breakthrough curves in monitoring contaminant transport. Tracer injection tests were conducted with three different types of saturated sands to obtain average linear velocities and longitudinal hydrodynamic dispersion coefficients based on BEC breakthrough curves and effluent solute breakthrough curves. Comparative analysis of transport parameters obtained from curve fitting the results into the analytical solutions confirmed the validity of resistance measurements in estimating time-continuous resident solute concentration. Under the assumption that a linear relationship exists between ${\sigma}_{sat}-{\sigma}_w-C$, the BEC breakthrough curves are able to effectively reduce the laborious and time-consuming processes involved in the conventional method of sampling and analysis. In order to reduce possible uncertainties in analyzing the BEC breakthrough curves, it was recommended that resistance measurements take place nearby the effluent boundary. In addition, a sufficient electrical contrast or difference in the electrical conductivity of the influent and the saturating solution is required to conduct reliable analysis.

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Analysis of Breakthrough Curves and Mass Transfer Resistance for Phenol Adsorption in a Fixed-bed Process Packed with Activated Carbon (활성탄을 충전한 고정층에서 페놀 흡착에 따른 파과곡선과 물질전달저항 해석)

  • You, Hae-Na;Kam, Sang-Kyu;Lee, Min-Gyu
    • Journal of Environmental Science International
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    • v.23 no.1
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    • pp.53-60
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    • 2014
  • Adsorption of phenol on activated carbon in a fixed bed was studied. The effects of fixed-bed length, superficial velocity (flow rate) and particle size of adsorbent on fixed-bed performance were investigated. Some characteristic parameters such as the breakthrough time ($t_{0.05}$), saturation time ($t_{0.95}$), length of mass transfer zone ($L_{MTZ}$), adsorptive capacity (W), and adsorption rate constant ($K_a$) were derived from the breakthrough curves. Adsorbent particle sizes significantly affected the shape of the breakthrough curve. Larger particle sizes resulted in an earlier breakthrough, a longer $L_{MTZ}$ and a lower adsorption rate. Superficial velocity was a critical factor for the external mass transfer during fixed-bed adsorption process. The external mass transfer resistance was dominant as increasing superficial velocity.

Adsorption Characteristics of Water Vapor on Zeolite (Zeolite의 수증기 흡착특성)

  • Lee, Song-Woo;Na, Young-Soo;An, Chang-Doeuk;Lee, Min-Gyu
    • Journal of Environmental Science International
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    • v.20 no.5
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    • pp.667-672
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    • 2011
  • The purpose of this work is to present the experiment results by a dynamic adsorption of water vapor on pelletized zeolites (ADZ300, ADZ400, and ADZ500) in fixed bed. The breakthrough curves of water vapor with several different concentrations and temperature in the range of 25~45 $^{\circ}C$ on zeolite bed were investigated. In the same conditions, the breakthrough time on ADZ400 and ADZ500 were little longer than ADZ300, and the equilibrium adsorption capacity on ADZ500 was highest. The higher the concentration of water vapor was, the faster the breakthrough time was, and the slope of breakthrough curves showed a tendency to increase. The faster the flow rate of water vapor was, the faster the breakthrough time was relatively, but variations between flow rate and breakthrough time did not have a proportional relationship. The breakthrough curve maintained constant gradient in spite of variation of flow rate in the same concentration. The temperature rise in zeolite bed by adsorption heat was occurred in the early stage of adsorption. After water molecule layers were formed on the surface of zeolite, the temperature was slowly cooled by water vapors continuously flowed in as constant temperature. The greater the concentration of water vapor and adsorption temperature were, the temperature difference in zeolite bed was increased.

A Study of $SO_2$ Adsorption Characteristics by Adsorbents in a Fixed Bed Reactor (고정층 반응기를 이용한 흡착제 종류에 따른 $SO_2$ 흡착특성에 관한 연구)

  • 조기철;홍성창;김희강
    • Journal of Korean Society for Atmospheric Environment
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    • v.15 no.2
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    • pp.191-199
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    • 1999
  • This study evaluated the availability as an alternative adsorbent which is cheaper and more efficient than CuO/${\gamma}$-$Al_2O_3$ which have been studing vigorously to remove $SO_2$. Five adsorbents (CuO/${\gamma}$-$Al_2O_3$, Iron ore, Slag, LD slag, $Fe_2O_3$) was employed in a fixed bed reactor. $SO_2$ breakthrough curves were obtained as a function of temperature, initial gas velocity and particle size. Saturation capacities calculated by the numerical integration of breakthrough curves of $SO_2$ increased with increasing reaction temperature. $SO_2$ breakthrough curve equation of $Fe_2O_3$ for this system can be expressed as Kr=3,914,000 exp(-37,329.86/RT). By means of the breakthrough curve, the influence of bed height on breakthrough time was also estimated.

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Experimental und Numerical Sensitivity Analyses on Push Pull Tracer Tests

  • Hwang, Hyeon-Tae;Lee, Gang-Geun
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • pp.312-316
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    • 2004
  • Single-well tracer tests, especially push pull tracer tests, are more effective to estimate hydraulic parameters and microbial metabolic activities in terms of duration and cost compared to multi-well tracer tests. However, there are some drawbacks in accuracy, complicated data analysis and uniqueness. These shortages are thought to be derived from the applied conditions which affect mass recovery curve and breakthrough curve. Factors such as extraction rate, resting period, hydraulic conductivity and hydraulic gradient are considered as the major factors determining the mass recovery rate and shape of the breakthrough curve. The results of the sensitivity analysis are summarized as follows: 1) the significant change in concentration of breakthrough curve is obtained when the extraction rate increases. This effect would also be much higher if the hydraulic conductivity is lower; 2) the mass recovery rate decreases with the increase of resting time, and the difference of mass recovery rates for different resting times is inversely proportional to the hydraulic conductivity; 3) the sensitivity values decrease with time. The hydraulic conductivity affects not only the early period, but the later period of the breakthrough curves; 4) The influence of the hydraulic gradient on the breakthrough curves is greater at earlier stage than at later stage. The mass recovery rate is inversely proportional to the hydraulic gradient.

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Modeling Study on Nuclide Transport in Ocean - an Ocean Compartment Model (해양에서의 핵종이동 모델링 - 해양구획 모델)

  • Lee, Youn-Myoung;Suh, Kyung-Suk;Han, Kyong-Won
    • Nuclear Engineering and Technology
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    • v.23 no.4
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    • pp.387-400
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    • 1991
  • An ocean compartment model simulating transport of nuclides by advection due to ocean circulation and intertaction with suspended sediments is developed, by which concentration breakthrough curves of nuclides can be calculated as a function of time. Dividing ocean into arbitrary number of characteristic compartments and performing a balance of mass of nuclides in each ocean compartment, the governing equation for the concentration in the ocean is obtained and a solution by the numerical integration is obtained. The integration method is specially useful for general stiff systems. For transfer coefficients describing advective transport between adjacent compartments by ocean circulation, the ocean turnover time is calculated by a two-dimensional numerical ocean model. To exemplify the compartment model, a reference case calculation for breakthrough curves of three nuclides in low-level radioactive wastes, Tc-99, Cs-137, and Pu-238 released from hypothetical repository under the seabed is carried out with five ocean compartments. Sensitivity analysis studies for some parameters to the concentration breakthrough curves are also made, which indicates that parameters such as ocean turnover time and ocean water volume of compartments have an important effect on the breakthrough curves.

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