Abstract
ABSTRACT
Laboratory and field experiments were conducted to examine an intermediate waste treatment process that involves adding an electrolyte (NaCl) at increased 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 constituents of a complex nonaqueous phase liquid (NAPL) extracted from the shallow 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 hydrophobic oil-rich phase, and a hydrophilic water-rich phase. Laboratory data indicated that at higher temperatures, lower amounts of salt were required to produce similar levels of volumetric phase separation of the SPME waste. The volumetric separations (aqueous/total) were on the order of ∼0.95 ±0.01 for samples taken during the first pore volume, and a composite volume of the flushing experiment. Partitioning of several NAPL constituents into the organic phase was usually greater than 96% of the mass present in the effluent SPME waste. A cost analysis suggests potential economic advantages of this intermediate waste management process.
Key words:
site remediation; waste treatment; NAPL; salt; in situ flushing.
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