JRW’s LactOil Nano™ incorporates iron compounds such as magnetite or green rust, with microemulsion technology for a new iron delivery system that promotes the distribution of micron-scale iron particles with a sub-micron carbon source. Recent research into the anaerobic degradation pathways of chlorinated ethenes, ethanes, and other anaerobically degradable contaminants has led to the evaluation of the contribution that biotic and abiotic mechanisms make to overall contaminant degradation.

The idea of combined biotic and abiotic mechanisms has historically not been investigated as the in-situ remediation industry grew from two different approaches, a biological approach and a chemical oxidation approach. Biological processes mainly revolved around the application of a carbon substrate to enhance reductive dechlorination. One evolution of this approach was the use of emulsified vegetable oil as a slow release substrate. Chemical processes evolved to include the use of minerals, predominantly zero valent iron (ZVI), as in-situ chemical reductants (ISCR). The main challenge with the introduction of an ISCR is a general inability to transport the solid material away from the injection points to ensure adequate coverage. As the biological mechanisms of anaerobic metabolism became better understood, it became apparent that many degradation pathways could not be easily attributable to strictly biological processes but fit easily into chemical reductive processes.

This led to the view that both processes might be contributing to the degradation of contaminants on sites with high metals content with the substrate acting not only as an electron donor for reductive dechlorination but also to “recharge” native metals to promote the chemical reduction of contaminants within the system. Data from some sites where there is evidence of both processes suggest that there may even be a synergistic effect from biotic and abiotic processes.

The current paradigm considers combining the benefits of chemical reduction using ISCRs with reductive dechlorination through the addition of a carbon substrate. The problem for practitioners is how to mix an insoluble ISCR with a soluble organic substrate to form a stable injectate. The use of microemulsion technology to biologically enhance reductive dechlorination is a relatively new technology to the remediation industry. Microemulsions combine two immiscible materials with surfactants to form sub-micron-sized particles that are thermodynamically stable. JRW’s LactOil^® soy microemulsion is prepared as a water-in-oil reverse microemulsion with a stability of greater than one year. After dilution, the microemulsion “flips” to form an oil-in-water microemulsion. Laboratory tests suggest that this dilute microemulsion remains stable for as long as 6 months. Since microemulsions are stable systems made up of sub-micron particles, they exhibit superior subsurface transport. A significant advantage is achieved when ISCRs are incorporated into the water fraction of a water-in-oil reverse microemulsion thereby combining both biological and abiotic mechanisms into one easily managed material that incorporates both biotic and abiotic remedial properties with the distribution characteristics of a liquid that transports in ground water like a miscible fluid.