PHASE-DIAGRAMS TO OPTIMIZE SURFACTANT SOLUTIONS FOR OIL AND DNAPL RECOVERY IN AQUIFERS

Phase diagrams can be used to optimize the composition of surfactant s olutions (cosurfactant/surfactant) designed for the recovery of DNAPLs at residual saturation in aquifer formations. The study also shows th at the combination of cosurfactant (alcohol) and surfactant is more ef fective than the use of alcohols or surfactants separately. The sugges ted approach is based on miscible oil displacement using surfactant so lutions at high concentrations. Most of the recent projects using surf actants for aquifer cleanup use low-concentration solutions that promo te immiscible oil displacement. The goal of the present study is to de monstrate the potential of optimized surfactant solutions to restore o il and DNAPL-contaminated sites such as the one in Ville Mercier, Queb ec (site contaminated with a mixture of petroleum and chlorinated solv ents). The results show that alcohol/surfactant systems can be used to solubilize chlorinated solvents (TCE, PCE) and light oils (gasoline, diesel). For the dissolution of heavy and viscous oils (motor oil, ATF , creosote, Ville Mercier oil), an organic solvent must be added to th e alcohol/surfactant system.