An improved method for injection of emulsified edible oils
A field demonstration of the technology at a former adhesive manufacturing facility is presented. Treatment consisted of creating a permeable reactive barrier (PRB) downgradient of the DNAPL source, and injection of emulsified oil amendment directly into the source area. The primary soil and groundwater contaminants consisted of 1,1,1-trichloroethane (1,1,1-TCA), trichloroethene (TCE), and their degradation products. An amendment formulation consisting of emulsified soybean oil and sodium lactate was developed to provide a balance of fast and slow-release electron donors. Using advanced factory processing, a high-quality emulsion consisting of oil droplets of uniform size under 0.5 micron was produced (patent #6,806,078). The concentrated oil-in-water emulsion (50% oil by volume) and sodium lactate was shipped to the site, and a proportional feed system was used to deliver a consistent concentration of the amendment into injection wells. Processing the material off-site and using a proportional feed system to inject simultaneously into multiple wells greatly reduced amendment injection costs. A marked increase in the production of degradation products including cis-1,2-dichloroethene (cDCE), 1,1-dichloroethene (1,1-DCE), vinyl chloride (VC), and ethene was observed during the first six months after amendment injection. The presence of volatile fatty acids, elevated total organic carbon, and high concentrations of ethene three years after injection indicates that the edible oil is able to support reductive dechlorination for long periods of time.