Experimental investigation of surfactant-enhanced dissolution of residual NAPL in saturated soil
Nonaqueous phase liquid (NAPL) is a long-term source of ground water contamination as the pollutant slowly partitions into the air and water phases. The objective of this work was to study the efficacy of aqueous surfactant solution to enhance the dissolution of a residual NAPL below the capillary fringe, hence reducing the time needed for aquifer restoration. An analytical technique was developed to measure the concentration of NAPL in a nonionic surfactant. Soil column experiments simulated conditions in the saturated soil where a NAPL may become trapped as a discontinuous immobile phase. Experimental results indicate that dissolution was a rate-limited process, approaching equilibrium concentrations after 24 hours. The relative permeability of the aqueous phase initially decreased as surfactant was injected, but increased over time as the saturation of residual NAPL was reduced through mass transfer into the surfactant-enhanced aqueous phase. These findings suggest that enhancing the aqueous phase with a nonionic surfactant may significantly enhance the in situ recovery of residual NAPL.
- Sponsoring Organization:
- Environmental Protection Agency, Washington, DC (United States); Michigan State Government, Lansing, MI (United States)
- OSTI ID:
- 556563
- Journal Information:
- Ground Water Monitoring and Remediation, Journal Name: Ground Water Monitoring and Remediation Journal Issue: 4 Vol. 17; ISSN GWMREV; ISSN 1069-3629
- Country of Publication:
- United States
- Language:
- English
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