Micromodel study of surfactant foam remediation of residual trichloroethylene

A remediation technique involving surfactant foam (SF) was investigated by using a micromodel with a view toward improved contaminant displacement. A residual trichloroethylene (TCE) saturation was emplaced in an otherwise wa ter-saturated micromodel. Air flow was introduced to a surfactant solution flow(Sodium C14-16 olefin sulfonate 2%(w)) commonly utilized in surfactant flushing to obtain the SF. Conventional remediation strategies, surfactant flushing, water flooding, and gas flooding were also employed for compariso n to the SF flooding. The removal efficiency was quantified by directly mea suring the remaining TCE blob area with an image analyzer. The micromodel v isualization showed that the SF is capable of displacing a higher amount of TCE as compared to surfactant solution alone. The SF flooding removed 99% of the residual TCE, while surfactant flushing removed 41% with 25 pore vol umes of the same surfactant solution. Based on micromodel visualization, th e resulting enhanced removal of TCE blobs due to direct and indirect displa cements, increased solubility and blob snap-off were investigated. The micr omodel was also oriented vertically, and no vertical movement of the TCE wa s observed during SF flooding. Thus, the SF flooding achieved high TCE remo val efficiency without lowering the interfacial tension to an ultralow valu e and causing vertical migration, which has been of particular concern in T CE removal.