The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Song-bae Kim - One of the best experts on this subject based on the ideXlab platform.
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Contaminant transport and biodegradation in saturated porous media: model development and simulation
Hydrological Processes, 2005Co-Authors: Song-bae KimAbstract:A mathematical model is developed to describe the contaminant transport, sorption, and biodegradation in saturated porous media. In the model development, sorption was accounted for as a kinetic process for the contaminant transport. In addition, a double Monod function was incorporated into the model to describe the biodegradation of Contaminants and utilization of oxygen. In the description of bacterial transport, reversible and irreversible depositions of bacteria were considered as kinetic processes in the model. The model equations were solved numerically with a fully implicit finite-difference method along with the Runge–Kutta method. The simulation showed that contaminant transport in porous media could be greatly affected by sorption and biodegradation processes. Sensitivity analysis demonstrated that the contaminant transport model was insensitive to the changes of desorption rate constant for Contaminants kb, half-saturation constant for oxygen Ko, bacterial yield factor Y, and oxygen use coefficient F. However, the model was sensitive to the changes of adsorption rate constant for Contaminants kf, maximum utilization rate of Contaminants µmax, and half-saturation constant for Contaminants Kc, and so their values should be selected carefully in the modelling process. Copyright © 2005 John Wiley & Sons, Ltd.
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Application of generalized contaminant retardation factor to a multi-phase system
Hydrological Processes, 2003Co-Authors: Song-bae Kim, Dong Ju KimAbstract:In this study, a generalized contaminant retardation factor applicable to a multiphase system where various types of colloids exist simultaneously with Contaminants is derived and incorporated into an equilibrium model which is successfully applied to experimental data for which phenanthrene was used as hydrophobic organic Contaminants and dissolved organic matter (DOM) or bacteria as mobile carriers. Based on the parameter values for the experimental data regarding the association of phenanthrene with solid matrix, DOM and various bacterial isolates, numerical experiments are performed to examine the transport behaviour of hydrophobic organic Contaminants in various types of the multiphase system. Numerical experiments demonstrate that the extent of contaminant transport enhancement depends on the adsorption affinity of the colloid, its concentration and its mobility, and that the importance of a third phase to contaminant transport needs to be evaluated carefully with respect to the relevance of experimental conditions applied to realistic environmental conditions. Copyright 2003 John Wiley & Sons, Ltd.
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effect of dissolved organic matter and bacteria on contaminant transport in riverbank filtration
Journal of Contaminant Hydrology, 2003Co-Authors: Song-bae Kim, Yavuz M Corapcioglu, Dong Ju KimAbstract:A mathematical model for the transport of hydrophobic organic Contaminants in an aquifer under simplistic riverbank filtration conditions is developed. The model considers a situation where Contaminants are present together with dissolved organic matter (DOM) and bacteria. The aquifer is conceptualized as a four-phase system: two mobile colloidal phases, an aqueous phase, and a stationary solid phase. An equilibrium approach is used to describe the interactions of Contaminants with DOM, bacteria, and solid matrix. The model is composed of bacterial transport equation and contaminant transport equation. Numerical simulations are performed to examine the contaminant transport behavior in the presence of DOM and bacteria. The simulation results illustrate that contaminant transport is enhanced markedly in the presence of DOM and bacteria, and the impact of DOM on contaminant mobility is greater than that of bacteria under examined conditions. Sensitivity analysis demonstrates that the model is sensitive to changes of three lumped parameters: K1 + (total affinity of stationary solid phase to Contaminants), K2 + (total affinity of DOM to Contaminants), and K3 + (total affinity of bacteria to Contaminants). In a situation where Contaminants exist simultaneously with DOM and bacteria, contaminant transport is mainly affected by a ratio of K1 + /K2 + /K3 + , which can vary with changes of equilibrium distribution coefficient of Contaminants and/or colloidal concentrations. In riverbank filtration, the influence of DOM and bacteria on the transport behavior of Contaminants should be accounted to accurately predict the contaminant mobility. D 2003 Elsevier Science B.V. All rights reserved.
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Effect of dissolved organic matter and bacteria on contaminant transport in riverbank filtration.
Journal of contaminant hydrology, 2003Co-Authors: Song-bae Kim, M Yavuz Corapcioglu, Dong Ju KimAbstract:A mathematical model for the transport of hydrophobic organic Contaminants in an aquifer under simplistic riverbank filtration conditions is developed. The model considers a situation where Contaminants are present together with dissolved organic matter (DOM) and bacteria. The aquifer is conceptualized as a four-phase system: two mobile colloidal phases, an aqueous phase, and a stationary solid phase. An equilibrium approach is used to describe the interactions of Contaminants with DOM, bacteria, and solid matrix. The model is composed of bacterial transport equation and contaminant transport equation. Numerical simulations are performed to examine the contaminant transport behavior in the presence of DOM and bacteria. The simulation results illustrate that contaminant transport is enhanced markedly in the presence of DOM and bacteria, and the impact of DOM on contaminant mobility is greater than that of bacteria under examined conditions. Sensitivity analysis demonstrates that the model is sensitive to changes of three lumped parameters: K+1 (total affinity of stationary solid phase to Contaminants), K+2 (total affinity of DOM to Contaminants), and K+3 (total affinity of bacteria to Contaminants). In a situation where Contaminants exist simultaneously with DOM and bacteria, contaminant transport is mainly affected by a ratio of K+1/K+2/K+3, which can vary with changes of equilibrium distribution coefficient of Contaminants and/or colloidal concentrations. In riverbank filtration, the influence of DOM and bacteria on the transport behavior of Contaminants should be accounted to accurately predict the contaminant mobility.
Dong Ju Kim - One of the best experts on this subject based on the ideXlab platform.
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Application of generalized contaminant retardation factor to a multi-phase system
Hydrological Processes, 2003Co-Authors: Song-bae Kim, Dong Ju KimAbstract:In this study, a generalized contaminant retardation factor applicable to a multiphase system where various types of colloids exist simultaneously with Contaminants is derived and incorporated into an equilibrium model which is successfully applied to experimental data for which phenanthrene was used as hydrophobic organic Contaminants and dissolved organic matter (DOM) or bacteria as mobile carriers. Based on the parameter values for the experimental data regarding the association of phenanthrene with solid matrix, DOM and various bacterial isolates, numerical experiments are performed to examine the transport behaviour of hydrophobic organic Contaminants in various types of the multiphase system. Numerical experiments demonstrate that the extent of contaminant transport enhancement depends on the adsorption affinity of the colloid, its concentration and its mobility, and that the importance of a third phase to contaminant transport needs to be evaluated carefully with respect to the relevance of experimental conditions applied to realistic environmental conditions. Copyright 2003 John Wiley & Sons, Ltd.
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effect of dissolved organic matter and bacteria on contaminant transport in riverbank filtration
Journal of Contaminant Hydrology, 2003Co-Authors: Song-bae Kim, Yavuz M Corapcioglu, Dong Ju KimAbstract:A mathematical model for the transport of hydrophobic organic Contaminants in an aquifer under simplistic riverbank filtration conditions is developed. The model considers a situation where Contaminants are present together with dissolved organic matter (DOM) and bacteria. The aquifer is conceptualized as a four-phase system: two mobile colloidal phases, an aqueous phase, and a stationary solid phase. An equilibrium approach is used to describe the interactions of Contaminants with DOM, bacteria, and solid matrix. The model is composed of bacterial transport equation and contaminant transport equation. Numerical simulations are performed to examine the contaminant transport behavior in the presence of DOM and bacteria. The simulation results illustrate that contaminant transport is enhanced markedly in the presence of DOM and bacteria, and the impact of DOM on contaminant mobility is greater than that of bacteria under examined conditions. Sensitivity analysis demonstrates that the model is sensitive to changes of three lumped parameters: K1 + (total affinity of stationary solid phase to Contaminants), K2 + (total affinity of DOM to Contaminants), and K3 + (total affinity of bacteria to Contaminants). In a situation where Contaminants exist simultaneously with DOM and bacteria, contaminant transport is mainly affected by a ratio of K1 + /K2 + /K3 + , which can vary with changes of equilibrium distribution coefficient of Contaminants and/or colloidal concentrations. In riverbank filtration, the influence of DOM and bacteria on the transport behavior of Contaminants should be accounted to accurately predict the contaminant mobility. D 2003 Elsevier Science B.V. All rights reserved.
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Effect of dissolved organic matter and bacteria on contaminant transport in riverbank filtration.
Journal of contaminant hydrology, 2003Co-Authors: Song-bae Kim, M Yavuz Corapcioglu, Dong Ju KimAbstract:A mathematical model for the transport of hydrophobic organic Contaminants in an aquifer under simplistic riverbank filtration conditions is developed. The model considers a situation where Contaminants are present together with dissolved organic matter (DOM) and bacteria. The aquifer is conceptualized as a four-phase system: two mobile colloidal phases, an aqueous phase, and a stationary solid phase. An equilibrium approach is used to describe the interactions of Contaminants with DOM, bacteria, and solid matrix. The model is composed of bacterial transport equation and contaminant transport equation. Numerical simulations are performed to examine the contaminant transport behavior in the presence of DOM and bacteria. The simulation results illustrate that contaminant transport is enhanced markedly in the presence of DOM and bacteria, and the impact of DOM on contaminant mobility is greater than that of bacteria under examined conditions. Sensitivity analysis demonstrates that the model is sensitive to changes of three lumped parameters: K+1 (total affinity of stationary solid phase to Contaminants), K+2 (total affinity of DOM to Contaminants), and K+3 (total affinity of bacteria to Contaminants). In a situation where Contaminants exist simultaneously with DOM and bacteria, contaminant transport is mainly affected by a ratio of K+1/K+2/K+3, which can vary with changes of equilibrium distribution coefficient of Contaminants and/or colloidal concentrations. In riverbank filtration, the influence of DOM and bacteria on the transport behavior of Contaminants should be accounted to accurately predict the contaminant mobility.
Clifton Davenport - One of the best experts on this subject based on the ideXlab platform.
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pump and treat accomplishments a review of the effectiveness of ground water remediation in santa clara valley california
Ground Water Monitoring and Remediation, 1995Co-Authors: Gregory Bartow, Clifton DavenportAbstract:Pump and treat has been successful in significantly reducing the volatile organic contaminant concentrations in ground water in Santa Clara Valley. California. The California Regional Water Quality Control Board. San Francisco Bay Region, currently oversees 61 sites in Santa Clara Valley with operating pump-and-treat systems, of which 42 sites have been extracting ground water since at least 1987. This review- evaluates the effects of ground water extraction on contaminant concentrations at 37 of those 42 sites. The evaluation focuses on trichloroethane, trichloroethene, and dichloroethane, as these were the most prevalent Contaminants encountered at the sites. The majority of sites obtained greater than 90 percent reduction in maximum concentrations for one or more of the three Contaminants. While only one of the 37 sites obtained maximum contaminant levels (MCL) for all Contaminants, six of the sites included in the analyses reached MCLs for one or more of the sampled Contaminants, and an additional seven of the sites are near MCLs for al least one contaminant. Our findings indicate that, while pump and treat successfully reduced maximum concentrations al most of the sites reviewed, successful attempts to reduce maximum contaminant concentrations to below MCLs are limited.
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Pump‐and‐Treat Accomplishments: A Review of the Effectiveness of Ground Water Remediation in Santa Clara Valley, California
Groundwater Monitoring & Remediation, 1995Co-Authors: Gregory Bartow, Clifton DavenportAbstract:Pump and treat has been successful in significantly reducing the volatile organic contaminant concentrations in ground water in Santa Clara Valley. California. The California Regional Water Quality Control Board. San Francisco Bay Region, currently oversees 61 sites in Santa Clara Valley with operating pump-and-treat systems, of which 42 sites have been extracting ground water since at least 1987. This review- evaluates the effects of ground water extraction on contaminant concentrations at 37 of those 42 sites. The evaluation focuses on trichloroethane, trichloroethene, and dichloroethane, as these were the most prevalent Contaminants encountered at the sites. The majority of sites obtained greater than 90 percent reduction in maximum concentrations for one or more of the three Contaminants. While only one of the 37 sites obtained maximum contaminant levels (MCL) for all Contaminants, six of the sites included in the analyses reached MCLs for one or more of the sampled Contaminants, and an additional seven of the sites are near MCLs for al least one contaminant. Our findings indicate that, while pump and treat successfully reduced maximum concentrations al most of the sites reviewed, successful attempts to reduce maximum contaminant concentrations to below MCLs are limited.
Mingyang Wang - One of the best experts on this subject based on the ideXlab platform.
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Rapid identification of multiple constantly-released contaminant sources in indoor environments with unknown release time
Building and Environment, 2014Co-Authors: Xianting Li, Zhilong Chen, Mingyang WangAbstract:Abstract The sudden release of airborne hazardous Contaminants in an indoor environment can potentially lead to severe disasters, such as the spread of toxic gases, fire, and explosion. To prevent and mitigate these disasters it is critical to rapidly and accurately identify the characteristics of the contaminant sources. Although remarkable achievements have been made in identifying a single indoor contaminant source in recent years, the issues related to multiple contaminant sources are still challenging. This study presents a method for identifying the exact locations, emission rates, and release time of multiple indoor contaminant sources simultaneously released at constant rates, by considering sensor thresholds and measurement errors. The method uses a two-stage procedure for rapid source identification. Before the release of Contaminants, only a limited number of time-consuming computational fluid dynamics (CFD) simulations need to be conducted. After the release of Contaminants, the method can be executed in real-time. Through case studies in a three-dimensional office the method was numerically demonstrated and validated, and the results show that the method is effective and feasible. The effects of sensor threshold, measurement error and total sampling time on the source identification performance were analysed, and the limitations and applicability of the method were also discussed.
Pal A Olsvik - One of the best experts on this subject based on the ideXlab platform.
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omega 3 and alpha tocopherol provide more protection against Contaminants in novel feeds for atlantic salmon salmo salar l than omega 6 and gamma tocopherol
Toxicology reports, 2016Co-Authors: Liv Softeland, Marc H G Berntssen, Jennifer Kirwan, Trond Rovik Storseth, Mark R Viant, Bente E Torstensen, Rune Waagbo, Pal A OlsvikAbstract:Extended use of plant ingredients in Atlantic salmon farming has increased the need for knowledge on the effects of new nutrients and Contaminants in plant based feeds on fish health and nutrient-contaminant interactions. Primary Atlantic salmon hepatocytes were exposed to a mixture of PAHs and pesticides alone or in combination with the nutrients ARA, EPA, α-tocopherol, and γ-tocopherol according to a factorial design. Cells were screened for effects using xCELLigence cytotoxicity screening, NMR spectroscopy metabolomics, mass spectrometry lipidomics and RT-qPCR transcriptomics. The cytotoxicity results suggest that adverse effects of the Contaminants can be counteracted by the nutrients. The lipidomics suggested effects on cell membrane stability and vitamin D metabolism after contaminant and fatty acid exposure. Co-exposure of the Contaminants with EPA or α-tocopherol contributed to an antagonistic effect in exposed cells, with reduced effects on the VTG and FABP4 transcripts. ARA and γ-tocopherol strengthened the contaminant-induced response, ARA by contributing to an additive and synergistic induction of CYP1A, CYP3A and CPT2, and γ-tocopherol by synergistically increasing ACOX1. Individually EPA and α-tocopherol seemed more beneficial than ARA and γ-tocopherol in preventing the adverse effects induced by the contaminant mixture, though a combination of all nutrients showed the greatest ameliorating effect.
