Field and laboratory evaluation of the treatment of DNAPL source zones using emulsified zero-valent iron.
Because the addition of nZVI in the source zone reduces contaminants, it increases the concentration gradient between the aqueous phase and DNAPLs, thereby increasing the mass transfer of contaminants from DNAPLs to the dissolved aqueous phase, where they are then treated (29).
2000, "Biologically Enhanced Dissolution of Tetrachloroethene DNAPL
Because the addition of nZVI in the source zone reduces" contaminants, it increases the concentration gradient between the aqueous phase and DNAPLs
, thereby increasing the mass transfer of contaminants from DNAPLs
to the dissolved aqueous phase, where they are then treated (Watlington 2005).
Once below ground, it is "difficult or impossible to recover all of the trapped residual DNAPL
," EPA says.
For the last few years, crews have been removing 75 to 100 gallons of DNAPL
every month, and the cleanup will continue indefinitely.
We now know that spatial variability in DNAPL
mass distribution within a source region is almost inevitable, and, consequently, that mass detection is extremely difficult and uncertain [e.
migration, hysteretic capillary forces cause retention of a portion of the liquid within the pores as discontinuous globules or ganglia [Lenhard et al.
Co-solvent flushing, also known as in situ flushing, is a technology that has recently been considered for removal of light and dense nonaqueous phase liquids (LNAPLs and DNAPLs
, respectively) from groundwater aquifers.
Kevin Warner, Robert Cowdery, and Randy Sillan from LFR's Tallahassee office will present a paper on "Remediation of DNAPL
PCE with In Situ Cosolvent Flushing.
Chlorinated solvent contamination is common in groundwater systems, resulting from subsurface accumulations of immiscible solvents which are part of a larger group of Dense Non-Aqueous Phase Liquids known as DNAPLs
Kueper and McWhorter (1991) modeled the flow of DNAPLs
in fractures and found that they moved through fractures relatively quickly with little attenuation.