Waste management of a microemulsion using electrolyte addition at increased temperatures

Laboratory and field experiments were conducted to examine an intermediate waste treatment process that involves adding an electrolyte (NaCl) at incre ased temperatures to a single-phase microemulsion (SPME) waste. An in situ flushing test performed at a Superfund site at Hill AFB, UT, was the source of the SPME waste. The produced fluids from extraction wells included cons tituents of a complex nonaqueous phase liquid (NAPL) extracted from the sha llow aquifer, as well as the surfactant-cosurfactant mixture (3.0% Brij 97, 2.5% n-pentanol) injected to enhance NAPL solubility. The treatment method is based on separation of the SPME waste into two immiscible phases: a hyd rophobic coil-rich phase, and a hydrophilic water-rich phase. Laboratory da ta indicated that at higher temperatures, lower amounts of salt were requir ed to produce similar levels of volumetric phase separation of the SPME was te. The volumetric separations (aqueous/total) were on the order of similar to 0.95 +/- 0.01 for samples taken during the first pore volume, and a com posite volume of the flushing experiment. Partitioning of several NAPL cons tituents into the organic phase was usually greater than 96% of the mass pr esent in the effluent SPME waste. A cost analysis suggests potential econom ic advantages of this intermediate waste management process.