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Book Stochastic Analysis of Dense Nonaqueous Phase Liquid Dissolution in Naturally Heterogeneous Subsurface Systems

Download or read book Stochastic Analysis of Dense Nonaqueous Phase Liquid Dissolution in Naturally Heterogeneous Subsurface Systems written by Xin Fu and published by . This book was released on 2002 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: (Cont.) The theoretical prediction is compared with the DNAPL concentration data from the Hanford site, where millions of pounds carbon tetrachloride were dumped in disposal facilities. In spite of the error and uncertainty involved in the field data, there is reasonable agreement between the field observations and the predicted mean DNAPL concentration field. It is concluded that the dominant factor affecting the field-scale DNAPL dissolution is the variability of the dissolution rate coefficient, which is a function of spatial distribution of DNAPL and permeability. The bypassing effect, reflecting the diversion of water flow around zones of high DNAPL saturation with low aqueous relative permeability, is another important factor that can reduce the effective dissolution rate significantly. The limitations of the study are discussed regarding the data collection and further evaluation of the extrapolation.

Book Dissolution of Non aqueous Phase Liquid Pools in Saturated Porous Media

Download or read book Dissolution of Non aqueous Phase Liquid Pools in Saturated Porous Media written by Michael P. Whelan and published by . This book was released on 1992 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Theoretical Analyses of Nonaqueous Phase Liquid Dissolution induced Instability in Two dimensional Fluid saturated Porous Media

Download or read book Theoretical Analyses of Nonaqueous Phase Liquid Dissolution induced Instability in Two dimensional Fluid saturated Porous Media written by Chongbin Zhao and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Non aqueous Phase Liquids NAPLs in Subsurface Environment

Download or read book Non aqueous Phase Liquids NAPLs in Subsurface Environment written by Lakshmi N. Reddi and published by . This book was released on 1996 with total page 880 pages. Available in PDF, EPUB and Kindle. Book excerpt: This collection contains 68 papers on contamination by nonaqueous phase liquids (NAPLs) presented at a specialty conference at the ASCE National Convention, held in Washington, D.C., November 10-14, 1996.

Book Nonaqueous Phase Liquid Dissolution in Porous Media

Download or read book Nonaqueous Phase Liquid Dissolution in Porous Media written by and published by . This book was released on 2007 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: Industrial organic solvents such as trichloroethylene (TCE) and tetrachloroethylene (PCE) constitute a principal class of groundwater contaminants. Cleanup of groundwater plume source areas associated with these compounds is problematic, in part, because the compounds often exist in the subsurface as dense nonaqueous phase liquids (DNAPLs). Ganglia (or 'blobs') of DNAPL serve as persistent sources of contaminants that are difficult to locate and remediate (e.g. Fenwick and Blunt, 1998). Current understanding of the physical and chemical processes associated with dissolution of DNAPLs in the subsurface is incomplete and yet is critical for evaluating long-term behavior of contaminant migration, groundwater cleanup, and the efficacy of source area cleanup technologies. As such, a goal of this project has been to contribute to this critical understanding by investigating the multi-phase, multi-component physics of DNAPL dissolution using state-of-the-art experimental and computational techniques. Through this research, we have explored efficient and accurate conceptual and numerical models for source area contaminant transport that can be used to better inform the modeling of source area contaminants, including those at the LLNL Superfund sites, to re-evaluate existing remediation technologies, and to inspire or develop new remediation strategies. The problem of DNAPL dissolution in natural porous media must be viewed in the context of several scales (Khachikian and Harmon, 2000), including the microscopic level at which capillary forces, viscous forces, and gravity/buoyancy forces are manifested at the scale of individual pores (Wilson and Conrad, 1984; Chatzis et al., 1988), the mesoscale where dissolution rates are strongly influenced by the local hydrodynamics, and the field-scale. Historically, the physico-chemical processes associated with DNAPL dissolution have been addressed through the use of lumped mass transfer coefficients which attempt to quantify the dissolution rate in response to local dissolved-phase concentrations distributed across the source area using a volume-averaging approach (Figure 1). The fundamental problem with the lumped mass transfer parameter is that its value is typically derived empirically through column-scale experiments that combine the effects of pore-scale flow, diffusion, and pore-scale geometry in a manner that does not provide a robust theoretical basis for upscaling. In our view, upscaling processes from the pore-scale to the field-scale requires new computational approaches (Held and Celia, 2001) that are directly linked to experimental studies of dissolution at the pore scale. As such, our investigation has been multi-pronged, combining theory, experiments, numerical modeling, new data analysis approaches, and a synthesis of previous studies (e.g. Glass et al, 2001; Keller et al., 2002) aimed at quantifying how the mechanisms controlling dissolution at the pore-scale control the long-term dissolution of source areas at larger scales.

Book Study of Transport and Dissolution of a Nonaqueous Phase Liquid in Porous Media

Download or read book Study of Transport and Dissolution of a Nonaqueous Phase Liquid in Porous Media written by Mirrya Mosier Fontenot and published by . This book was released on 2001 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: The transport and dissolution of residual non-aqueous phase liquids (NAPLS) trapped in water saturated porous media is a problem pertinent to both environmental and petrochemical industries. In this work we have quantitatively examined the complete dissolution of residual entrapped NAPL at the pore-scale in three dimensions using refractive index matching techniques along with planar laser induced fluorescence. The results yielded pore-scale information regarding ganglia volume, surface area, and position over time at various Capillary numbers. We found that with increasing Capillary numbers, the time for total dissolution decreased. In addition, it appears that large ganglia exhibit fractal area to volume scaling. We were also able to examine the distributions of the ganglia in the direction of flow over time. The use of low-frequency flow pulsations as a removal technique was also examined. A two dimensional micro model was used for these studies. We found that for this system, lower frequencies and higher amplitudes were more effective in NAPL removal due to breakup and mobilization. We also examined the effect of increasing amplitude and continuous versus pulsed stimulation. In addition, mass transport in the presence of a surfactant was also enhanced due to flow pulsation with lower frequencies and higher amplitudes again being most effective.

Book Light Nonaqueous Phase Liquids

Download or read book Light Nonaqueous Phase Liquids written by and published by . This book was released on 1995 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Nonaqueous phase Liquids

Download or read book Nonaqueous phase Liquids written by Godage B. Wickramanayake and published by . This book was released on 1998 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt: - Fractured Media- DNAPL Movement- DNAPL Behavior- Simulation of DNAPL Multiphase Flow and Transport- Characterization of Source Zones- DNAPL Recovery Systems- NAPL Remediation.

Book Characterization Dissolution and Enhanced Solubilization of Multicomponent Nonaqueous Phase Liquid in Porous Media

Download or read book Characterization Dissolution and Enhanced Solubilization of Multicomponent Nonaqueous Phase Liquid in Porous Media written by Kenneth Cooper Carroll and published by . This book was released on 2007 with total page 518 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multicomponent nonaqueous phase liquids (NAPL) contaminating the subsurface can significantly inhibit remediation. One method of enhancing the rate of remediation of NAPL constituents, compared to pump-and-treat, involves source zone treatment with enhanced solubilization agents (ESAs) including cyclodextrins. Equilibrium cyclodextrin enhanced solubilization of simple 1, 2, and 3 component NAPL mixtures was examined to evaluate the applicability of Raoult's Law. The results suggest that Raoult's Law may be used to estimate equilibrium and early-time dynamic concentrations in contact with ideal NAPL mixtures, and Raoult's Law may be used to estimate cyclodextrin enhanced groundwater concentrations for ideal NAPL mixtures. Solubility enhancement of NAPL compounds was dependent on the cyclodextrin concentration and independent of NAPL composition. Column experiments and numerical modeling were used to evaluate the dissolution behavior of the NAPL mixtures in water and a cyclodextrin solution to estimate mass transfer rates. The aqueous multicomponent dissolution followed Raoult's Law, and the model-estimated lumped rate coefficients were independent of the NAPL composition. Addition of the cyclodextrin enhanced the dissolution and removal of compounds from residual NAPL due to an increase in the driving force (i.e. concentration gradient) and the mass transfer coefficient. The model results suggest that Raoult's Law is applicable for ideal NAPL mixture dissolution in water, but potential nonideality was observed and caused the model simulation to deviate from the dissolution behavior for NAPL mixture cyclodextrin experiments. The cyclodextrin dissolution experiments were less rate-limited than aqueous dissolution, and the mass transfer coefficients were quantified with the model. The results of the model suggest that NAPL mixture nonideality and intra-NAPL diffusion may also impact enhanced dissolution behavior. Additionally, the importance of NAPL mixture characterization was illustrated by evaluation of a mixture of PCE (tetrachloroethene) and diesel fuel collected from a site in Tucson, Arizona. A sample from the site was used to create mixtures with increasing PCE in the NAPL. Chemical evaluation of the complex NAPL was conducted, and physical property and phase partitioning testing was performed, which demonstrated the effect of NAPL composition on its distribution, interphase mass transfer, and potential mobilization.