October 15, 2001

Civil Engineering Research Finds Edible Oils Can Clean Up Toxins in Groundwater

What if workers could inject simple cooking oil into contaminated ground to clean up toxic chemicals?  Sound too good to be true?  Not according to Dr. Robert C. Borden, professor of civil engineering at North Carolina State University. 

For several years Borden has been evaluating soybean and other cooking oils for their remediation, or clean up, capabilities.  He is working with the Raleigh consulting firm Solutions Industrial & Environmental Services Inc. to apply the results of research conducted at NC State. 

This research involves using an emulsion of cooking oil and a food grade emulsifier to create a “milky broth.”  This broth, when injected into the soil around a contaminated groundwater aquifer, becomes a food source for bacteria that can break down toxic chemicals.  Bacteria naturally present in soil around contaminated sites have “learned” to degrade toxins, but they need the encouragement of a steady food supply to work efficiently.

Borden’s research found that the emulsion performed much better than cooking oil alone for toxin remediation.  His system, which creates an oily barrier through which the groundwater flows and becomes purified, has been shown to work well to remediate contamination from chlorinated solvents in groundwater.  As always there are concerns about using such techniques to clean up pollution.  A focus of the research is the effect injecting an oily emulsion has on the permeability of the aquifer in soils of various textures.

Other challenges also remain to be addressed by ongoing research.  Borden will be comparing costs and benefits over many years to determine if this technology will be practical in the long term.  Cooking oil remediation is cheaper and more efficient than some commonly used clean-up techniques, such as pumping out aquifers or creating iron barrier walls.  However, Borden has yet to determine how long lasting the oil emulsion will be when applied to a real-world situation.  He also needs to determine how the emulsion can be distributed effectively to clean up aquifers of various depths and in clay or sandy soils. 

Borden’s current research involves investigating these questions partly by monitoring existing remediation sites.  By monitoring and evaluating these working sites, Borden can determine ways to make the process more efficient as well as answering some of his research questions.

Future applications for this research could include broader remediation efforts for many types of pollutants.  So far, most of Borden’s work has involved tetrachloroethene and trichloroethene, chlorinated solvents that are widespread and highly problematic groundwater pollutants.  Current work is looking at other types of chlorinated solvents as well as nitrate pollution from agricultural operations as possible candidates for cooking oil remediation.

Borden’s technology has the potential to be an important element of remediation efforts nationwide.  As we strive to keep our groundwater aquifers pure, exploring novel and creative remediation alternatives through research and application becomes more and more essential.

-- rudd --

Media Contacts:  Dr.Robert C. Borden, 919/515-1625, rcborden@eos.ncsu.edu, Linda E. Rudd, 919/515-3848, linda_rudd@ncsu.edu