A major contamination issue at over 8,000 sites in the United States are PAHs. This contamination results from almost all combustion processes, creosote treatment of wood, former town gas sites, and many others. Many of these chemicals are both toxic and carcinogenic. It has been observed that these highly hydrophobic chemicals bind tightly to soil by a number of possible interactions between the soil mineral matrix, the organic fraction of the soil, and the chemicals. Microbes in the soil appear to mediate these processes in some circumstances. Most of the PAHs are biodegraded by microorganisms, at least partially. The chemical sequestered in the soil is not biologically available to be toxic or biodegraded. The cleanup of many PAH-contaminated sites is impeded by the nonavailability of the chemicals either for removal or biodegradation. The proposed research has revealed that a microbally-based process can be used to mobilize PAHs and potentially other hydrophobic chemicals from soil. It appears that under high-reducing conditions, a community of anaerobic bacteria utilize the hydrogen ions in solution as electron donors, raising the pH of the soil. As the pH rises, the organic fraction of the soil is solubilized, taking the associated PAHs into solution with it. In the dissolved from the PAHs are biodegradable. This Phase I SBIR proposal seeks to expand these findings by testing soils with a variety of properties to determine how broadly applicable the technology may be for site remediation; examining the number of approaches for efficiently and cheaply establishing highly-reducing conditions in soil so the PAHs will be released; and developing and testing several potential methods for biodegrading the released PAHs. A Phase II proposal will conduct a field test of the method at an actual PAH site. The collaborators in this project are Dr. Frederic Pfaender of the Department of Environmental Sciences and Engineering at the University of North Carolina at Chapel Hill, Dr. J. Ronald Hass of Chatham Research Ltd (small business partner), and Dr. Gaylen Brubaker of RETEC NC Inc. (a remediation firm).
