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Keywords:

  • Contaminant transport;
  • NAPL dissolution;
  • acoustic waves;
  • enhanced mass transfer;
  • aquifer remediation

Abstract

The effects of acoustic waves on the dissolution of dense nonaqueous phase liquids in water saturated porous media are investigated. Experiments of trichloroethylene (TCE) ganglia dissolution within a water saturated column, packed with glass beads, are conducted. Acoustic waves with pressure amplitudes ranging from 0 to 1625 Pa and frequencies ranging from 0 to 285 Hz are employed to the interstitial fluid at the inlet of the packed column. Effluent dissolved TCE concentrations are observed to increase up to 120% in the presence of acoustic pressure waves compared to the case where TCE dissolution without acoustic waves is monitored. The observed effluent dissolved TCE concentration increase is attributed to enhanced mass flux at the TCE-water interface, caused by acoustic waves. Highest dissolution rates occur at discrete frequencies suggesting resonance effects or the presence of standing waves. Although acoustic waves enhance TCE dissolution, they dissipate almost exponentially with distance from the acoustic source. © 2004 American Institute of Chemical Engineers AIChE J, 50: 3271–3280, 2004