The present work focuses on the remediation of contaminated aquifers by hydrophobic organic contaminants, such as hydrocarbons or chlorinated solvents, following the approach of Surfactant Enhanced Aquifer Remediation (SEAR) technology, based on the use of surfactants for the solubilization and mobilization of pollutants.
In this context, surfactin, a lipopeptide biosurfactant produced by Bacillus Subtilis, was selected as reference material for the NAPLs mobilization study. After a preliminary characterization of surfactin for the experimental evaluation of its physicochemical parameters (critical micelle concentration and surface behavior), the study involved in a batch configuration test in which toluene and perchloroethylene adsorption on a porous material was investigated in the presence and in the absence of surfactin as an indirect way to evaluate mobilization ability of surfactin through the reduction of NAPLs adsorption.
Experimental measurements highlighted a relatively low CMC value (2.45 x 10-2 g L-1) and a great tendency of surfactin to adsorb at the surfaces or interfaces. The batch test showed that the surfactin solution had no effects on the adsorption of toluene and PCE. On the other hand, surfactin led to an important decrease in the affinity between dissolved pollutants and solid surface. In general, these results suggest the possibility of using surfactin in the enhanced surfactant remediation technology.