Composite analytical solutions for a soil vapour extraction system
Article first published online: 7 DEC 2006
Copyright © 2006 John Wiley & Sons, Ltd.
Volume 21, Issue 11, pages 1506–1516, 30 May 2007
How to Cite
Chen, J.-S., Liang, C.-P., Chen, C.-Y. and Liu, C.-W. (2007), Composite analytical solutions for a soil vapour extraction system. Hydrol. Process., 21: 1506–1516. doi: 10.1002/hyp.6341
- Issue published online: 16 APR 2007
- Article first published online: 7 DEC 2006
- Manuscript Accepted: 2 MAY 2006
- Manuscript Received: 26 OCT 2005
- National Science Council of the Republic of China. Grant Number: Nos. NSC 92-2313-B-008-002 and NSC 93-2313-B-008-001
- soil vapour extraction;
- composite analytical solution;
- effluent concentration;
- Peclet number
Soil vapour extraction (SVE) is a common remediation technique for cleaning up unsaturated soils contaminated by volatile organic compounds (VOCs). Analytical solutions, which result from simple mathematical models, can allow the fast approximation of the time-dependent effluent concentration and the gaining of insight into the processes that take place during soil remediation. Deriving the analytical solutions to advection–dispersion equations that simultaneously take into account the mechanical dispersion and molecular diffusion is very difficult because of the variable dependence of governing equations' coefficients. In this study, we first present two simplified analytical solutions that only consider mechanical dispersion or molecular diffusion. The two developed analytical solutions are compared with the numerical solution that simultaneously considers both mechanical dispersion and molecular diffusion to examine the applicability of the two simplified analytical solutions and distinguishes the individual contribution of the mechanical dispersion and molecular diffusion to total VOCs transport in an SVE system. Results show that dispersion plays an important role during SVE decontamination and neither the diffusion-dominated solution nor the dispersion-dominated solution can agree well with the numerical solution when both mechanical dispersion and molecular diffusion have significant contributions to the total VOCs transport flux. A composite analytical solution that linearly couples the diffusion- and dispersion-dominated analytical solutions, which is proposed herein to eliminate the discrepancy between the analytical solutions and the numerical solution. Results indicate that the proposed composite analytical solution agrees well with the numerical solution and is an effective tool for quickly and accurately evaluating the time-dependent effluent concentration for parameters of the different ranges of interest in an SVE remedial system. Copyright © 2006 John Wiley & Sons, Ltd.