Surfactant Foam/Bioaugmentation Technology for In Situ Treatment of TCE-DNAPLs

• Published in: Environmental science & technology Vol. 32; no. 11; pp. 1667 - 1675
• Main Authors: Rothmel, Randi K, Peters, Robert W, St. Martin, Edward, DeFlaun, Mary F
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.06.1998
• Subjects: Applied sciences; AQUIFERS; BACTERIA; BIODEGRADATION; BIOREMEDIATION; Chemistry; CONTAMINATION; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; ENVIRONMENTAL SCIENCES; Exact sciences and technology; Groundwaters; Natural water pollution; PHYSICAL PROPERTIES; Pollution; Pollution, environment geology; RETENTION; SAND; SEDIMENTS; SOLVENTS; STRAINS; SURFACTANTS; Technology; VOCs; Volatile organic compounds; Water treatment and pollution; Organic solvent; Decontamination; Foam; Chlorine Organic compounds; Water pollution; Surfactant; Sediments; Bioaugmentation; Non aqueous phase liquid; Ground water; Ethylene(trichloro); Aquifers
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es970980w

Chlorinated solvents such as trichloroethylene (TCE) are prevalent aquifer contaminants. Depending on the degree of contamination, their physical properties may cause them to occur as dense nonaqueous-phase liquids (DNAPLs) making them difficult to remediate by pump-and-treat methods. Successful in situ bioremediation requires mobilization and dispersion of DNAPLs in order to reduce sediment concentrations to levels nontoxic to degradative bacteria. A bench-scale study was conducted to evaluate a novel remediation technology that utilized surfactant foam for mobilizing and dispersing TCE-DNAPLs combined with a bioaugmentation technology to remediate TCE in situ. Results using the anionic surfactant Steol CS-330 showed that foam injected into TCE-DNAPL-contaminated sand columns enhanced mobilization of TCE-DNAPLs. Mobilization was maximized when the foam was injected in a pulsed operation. Injection of foam followed by artificial groundwater (AGW) and then by foam again resulted in flushing 75% of the initial TCE-DNAPL through an 8-in. column (884 cm3 of sand). The residual TCE was dispersed within the column at concentration levels compatible with biodegradation (<500 μg/g). Adding the TCE-degrading bacterial strain ENV 435 simultaneously with the second pulse of foam resulted in 95−99% degradation of the residual TCE. This level of remediation was achieved with a total of 3 pore volumes (foam/AGW/foam + bacteria) and an aqueous column retention time of 1 h.