Influence of aqueous film forming foams on the solubility and mobilization of non-aqueous phase liquid contaminants in quartz sands

At sites where aqueous film forming foams (AFFFs) are used for fire suppression or training activities, interactions between dissolved foam constituents and organic liquids could alter contaminant migration in the subsurface. In this study, batch reactor column experiments were conducted to investigate potential AFFF solutions enhance solubility mobility of three representative non-aqueous phase liquid (NAPLs), JP-4 jet fuel, trichloroethene (TCE), tetrachloroethene (PCE). For concentrations up 5% wt. (50,000 mg/L), solubilities TCE PCE increased by less than 50%, indicating absence micellar solubilization. However, NAPL-water interfacial tensions reduced 1.5 mN/m resulted accumulation 2.25 mg/m2 at interface. To assess mobilize residual (entrapped) NAPL a field application rate 3% (30,000 columns packed with two size fractions Ottawa sands (20–30 mesh 60–80 mesh) that yielded saturations ranging from 11.7 17.6%. Following injection 3 pore volumes solution, partial mobilization was observed PCE, TCE, JP-4, saturation reductions 0.7 2% 20–30 0.3% 1.3% sand. The then flushed an ultralow-IFT surfactant solution consisting 4% 1:1 Aerosol AY/OT, which nearly complete remaining NAPL. When desaturation curves expressed terms total trapping number (NT), threshold value NT required approximately 2 × 10−5, consistent previous studies. These findings demonstrate can lead NAPL, concept be predict such behavior priori. addition, IFT sufficient redistribution subsurface through enhanced spreading above water table (e.g., JP-4) penetration into lower-permeability media PCE).