Analytical Model for Removal of a Uniformly Distributed Single-Component NAPL Under Nonequilibrium Conditions |
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| Authors: | H.J.H. Brouwers D.C.M. Augustijn |
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| Affiliation: | H.J.H. (Jos) Brouwers (Department of Civil Engineering, University of Twente, P.O. Box 217,7500 AE Enschede, The Netherlands) is an associate professor in the Department of Civil Engineering at the University of Twente, the Netherlands, a position he has held since 1992. His teaching and research is in the field of soil remediation, waste solidification, and material science.;D.C.M (Denie) Augustijn is an assistant professor in environmental science and joined the Department of Civil Engineering at the University of Twente in 1994. His teaching and research focuses on environmental management, water quality, and contaminant transport. |
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| Abstract: | In this paper a simple analytical model is presented for the one-dimensional transport equation describing the removal of a uniformly distributed, single-component NAPL under nonequilibrium conditions. Both advective and dispersive transport are included in the model. The model describes two distinct stages: a solution for the time the amount of NAPL declines but the length of the NAPL-containing region remains constant, and a solution from the moment the front, behind which all NAPL is depleted, starts to move. The model is valid for both dissolution (i.e., by water) or volatilization (i.e., by air). Dissolution (or volatilization) is considered a firstorder rate process with a constant mass-transfer rate coefficient. As expected, the model approaches the solution for equilibrium conditions if the mass-transfer coefficient tends to infinity. Even though the model is based on some rigorous assumptions, the simplicity of the model makes it useful for obtaining an initial mass-transfer rate coefficient from experimental data, which can be used to estimate the time required to dissolve all NAPL, as shown for two data sets taken from the literature. |
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