Comparison of primary and secondary surfactant flushing to enhance LNAPL recovery

Column experiments were conducted to compare the use of surfactants as a part of primary pumping to remove free phase NAPL to the use of surfactants to reduce or recover residual LNAPL in secondary treatment. Eight surfactant blends were tested, for a total of 48 column experiments. The column experiments show that the use of surfactants during primary pumping: (1) can potentially increase the amount of free product recovered; (2) can potentially reduce the amount of residual NAPL remaining after primary pumping; and (3) performs better than the use of surfactants to mobilize trapped residual NAPL.