REMOVAL OF VOLATILE ORGANIC-COMPOUNDS HORN SURFACTANT SOLUTIONS BY FLASH VACUUM STRIPPING IN A PACKED-COLUMN

Volatile organic compounds (VOCs) can be removed from contaminated gro und water and subsurface media by surfactant-enhanced remediation proc esses. For the process to be economically competitive it is necessary to recover and reuse the surfactant from this concentrated solution. T he VOC can be removed from this concentrated solution by flash vacuum stripping, leaving the surfactant solution for reuse. In this study, t he flash vacuum stripping of trichloroethylene (TCE) from an anionic s urfactant solution in a co-current packed column was studied under rou gh vacuum conditions. The presence of surfactants lead to a reduction in the overall liquid phase volumetric mass transfer coefficient (MTC) of 40 to 95%, depending on flow rate and surfactant concentration at 50 degrees C and 16 kPa. At liquid loading rates of less than 13 cm(3) /cm(2)min, the MTC of TCE decreases rapidly with an increase in liquid loading rate, and at liquid loading rates above that, the MTC decreas es slightly with an increase in the liquid loading rate. This trend ma y have been due to foaming. At surfactant concentrations above the cri tical micelle concentration, the effect of surfactant concentration wa s not significant at liquid loading rates less than 13 cm(3)/cm(2)min. However, beyond that rate, the MTC of TCE decreased drastically with an increase in surfactant concentration. The MTC of TCE increased with an increase in temperature. A large pressure drop (3 to 4 kPa/m) was observed across the packed bed due to foaming.