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ENHANCED CONTACT OF COSOLVENT AND DNAPL IN POROUS MEDIA BY CONCURRENT INJECTION OF COSOLVENT AND AIR
Citation:
Jeong, S. W., A L. Wood*, AND T R. Lee*. ENHANCED CONTACT OF COSOLVENT AND DNAPL IN POROUS MEDIA BY CONCURRENT INJECTION OF COSOLVENT AND AIR. ENVIRONMENTAL SCIENCE & TECHNOLOGY 36(23):5238-5244, (2002).
Description:
Remediation of sites contaminated by dense nonaqueous phase liquids (DNAPLS) is a major
environmental problem and cosolvent flooding is proposed as a remedial alternative. The
efficacy of cosolvent flooding is a function of the degree of mixing between the injected
remedial fluid and the resident DNAPL. Poor mixing may result from remedial fluids traveling
in the preferential flow paths which bypass trapped DNAPL. This study evaluated the concurrent injection of cosolvent and air to improve the sweep efficiency of cosolvent flooding in porous media. A 70% ethanol/30% water (v/v) cosolvent solution was injected simultaneously with air into a micromodel containing residual tetrachloroethylene (PCE). Double drainage displacement was observed as a dominant displacement mechanism in the initial period of the cosolvent-air flooding, i.e., gas phase displaced PCE that displaced water. The residual PCE residing in the preferential paths traversed by air was readily displaced. After the PCE mobilization by drainage mechanisms, the displacement of gas through the porous medium improves the flow distribution and dynamics of the cosolvent solution in porous media. Facilitated dissolution of PCE was observed throughout the porous medium.