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J Contam Hydrol

Title:		Steam stripping of the unsaturated zone of contaminated sub-soils: the effect of diffusion/dispersion in the start-up phase
Author(s):		Brouwers HJ; Gilding BH;
Address:		"Department of Construction Technology, Faculty of Engineering Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands. h.j.h.brouwers@utwente.nl"
Journal Title:		J Contam Hydrol
Year:		2006
Volume:		20051215
Issue:		1-Feb
Page Number:		1 - 26
DOI:		10.1016/j.jconhyd.2005.09.003
ISSN/ISBN:		0169-7722 (Print) 0169-7722 (Linking)
Abstract:		"The unsteady process of steam stripping of the unsaturated zone of soils contaminated with volatile organic compounds (VOCs) is addressed. A model is presented. It accounts for the effects of water and contaminants remaining in vapour phase, as well as diffusion and dispersion of contaminants in this phase. The model has two components. The first is a one-dimensional description of the propagation of a steam front in the start-up phase. This is based on Darcy's law and conservation laws of mass and energy. The second component describes the transport of volatile contaminants. Taking the view that non-equilibrium between liquid and vapour phases exists, it accounts for evaporation, transport, and condensation at the front. This leads to a moving-boundary problem. The moving-boundary problem is brought into a fixed domain by a suitable transformation of the governing partial differential equations, and solved numerically. For a broad range of the governing dimensionless numbers, such as the Henry, Merkel and Peclet numbers, computational results are discussed. A mathematical asymptotic analysis supports this discussion. The range of parameter values for which the model is valid is investigated. Diffusion and dispersion are shown to be of qualitative importance, but to have little quantitative effect in the start-up phase"
Keywords:		"Diffusion *Models, Theoretical Organic Chemicals/*isolation & purification Soil Pollutants/*isolation & purification *Steam Volatilization Waste Management/*methods Water Movements;"
Notes:		"MedlineBrouwers, H J H Gilding, B H eng Netherlands 2005/12/20 J Contam Hydrol. 2006 Feb 1; 83(1-2):1-26. doi: 10.1016/j.jconhyd.2005.09.003. Epub 2005 Dec 15"