AN EXPERIMENTAL STUDY OF BEHAVIOR OF VEGETABLE OIL EMULSIONS IN SANDY SOILS ASSOCIATED WITH DNAPL SITE REMEDIATION

The use of chlorinated solvent in the form of dense non-aqueous phase liquids (DNAPLs) such as dry cleaning agents, machine part cleaners etc. has resulted in contamination problems that require the development of cost effective and innovative remediation techniques. One such technique involves the injection of vegetable oil and vegetable oil emulsion into aquifers. As a substrate, food grade vegetable oil can provide consistently slow released but necessary carbon for biodegradation. Additionally, when injected into the subsurface as an emulsion containing vegetable oil, lecithin and water, the oil acts as a co-solvent. Little testing has been done related to the behavior of these emulsions in the subsurface. One dimensional testing in sand packed columns is in progress to determine to what extent emulsion entrainment occurs by varying such parameters as emulsion droplet size and soil type. These tests will help to characterize the effects of colloidal distribution on different sand types by examining hydraulic conductivity and dispersivity variations. Further, one dimensional testing is also in progress in glass columns where the emulsions behavior is investigated in the presence of PCE. Through partitioning tracer tests and destructive sampling, conclusions can be drawn as to the extent of residual free product recovery. Combining these tests, a better understanding of the behavior of these emulsions when they are flushed through a chlorinated solvent contaminated region could be obtained. Preliminary results of this laboratory investigation are presented.