Micellar-Enhanced Ultrafiltration and Air Stripping for Surfactant-Contaminant Separation and Surfactant Reuse

Authors

  • K. Michelle Lipe,

    1. K. Michelle Lipe is a staff environmental engineer with Dames & Moore (2021 S. Lewis Ave., Ste. 660, Tulsa, OK 74104). She received bachelor's and master's degrees in civil engineering with a specialty in process design from the University of Oklahoma. Her present work focuses on process design for industrial and ground water treatment.
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  • David A. Sabatini,

    1. David A. Sabatini is an associate professor of civil engineering and environmental science at the University of Oklahoma (202 W. Boyd, Rm. 334, University of Oklahoma, Norman, OK 73019). His research interests are in the areas of ground water contaminant transport and remediation, with a current emphasis on surfactant-based remediation technologies.
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  • Mark A. Hasegawa,

    1. Mark Hasegawa is an environmental engineer with Trust Environmental Services (2227 W. Lindsey, Norman, OK 73069). He received a master's degree in civil engineering with a specialty in solid and hazardous waste from the University of Oklahoma. He also received a bachelor's degree in civil engineering from Brigham Young University. His present work focuses on ground water investigation and remediation.
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  • Jeffrey H. Harwell

    1. Jeffrey H. Harwell is professor and director of the Chemical Engineering and Materials Science Department at the University of Oklahoma (The Institute for Applied Surfactant Research, University of Oklahoma, Norman, OK 73019). His research interest is in innovative applications of surfactant technologies, including such applications as soil remediation, natural gas storage, and ultrathin films.
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Abstract

Micellar-enhanced ultrafiltration (MELT) and air stripping were evaluated for surfactant-contaminant separation and surfactant recovery. Two linear alkyl diphenyloxide disulfonate (DPDS) surfactants were evaluated with the contaminants naphthalene and trichloroethylene. A separation model developed from micellar partitioning principles showed a good correlation to batch MEUF studies, whereas flux analysis highlighted concentration polarization effects in relation to hydrophobe length. MEUF effectively concentrated the surfactant-contaminant system (93 to 99 percent retention); however, this did not result in surfactant-contaminant separation. Batch and continuous flow air stripping models were developed based upon air/water ratio, surfactant concentration, and Micellar partitioning; model predictions were validated by experimental data. Sensitivity analyses illustrated the decline in contaminant-surfactant separation with increasing surfactant concentration (e.g., TCE removal efficiency declines from 83 percent to 37 percent as C-16 DPDS concentration increases from 0 to 55 mM). This effect is greater for more hydrophobic contaminants (naphthalene vs. TCE) and surfactants with greater solubilization potential (C16-DPDS vs. C-12 DPDS). The resulting design equations can account for this effect and thus properly size air strippers to achieve the desired removal efficiency in the presence of surfactant micelles. Proper selection and design of surfactant-contaminant separation and surfactant recovery systems are integral to optimizing surfactant-enhanced subsurface remediation.

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