Bioremediation of DNAPLs Team Leader Naji Akladiss 207-287-7709 naji.n.akladiss@maine.gov

The ITRC BioDNAPL Team is developing a technical and regulatory guidance document for bioremediation of DNAPLs associated with chlorinated solvents. Many developing technologies used to remediate DNAPL require introduction of energy (steam, heat), fluids (surfactants), or chemicals (KMNO 4 ) primarily to mobilize DNAPL so that it can subsequently be recovered. The promise of bioremediation is that microorganism—which can proliferate and attack the DNAPL without mobilization—might provide a far more efficient, effective, and less costly remediation.

There may be regulatory barriers—both real and perceived—to the introduction of remediation fluids and bacteria, and there is doubt related to the effectiveness of this technology. These barriers are expected to be primarily at the state level, and may include issues expressed by cleanup programs, health programs, and Underground Injection Control programs.

DNAPLs—primarily contaminants containing chlorinated solvents—pose one of the most widespread and prominent types of contamination associated with Superfund sites. The total number of DNAPL sites in the United States is well over 10,000. Typical industries faced with DNAPL cleanup include chemical manufacturing, aerospace, semiconductor and electronics, and dry cleaning.

The Remediation Technology Development Forum (RTDF) is researching bioremediation technology to reduce, remove, or eliminate DNAPL from a source zone. The next phase—actual field experiments and pilot-scale demonstrations—is underway. At present many promising test sites exist in the US and in England. The ITRC BioDNAPL team is tracking the development, demonstration, and deployment of this new technology for remediating DNAPLs.

Future topics to be covered by team products include microbial ecology, DNA typing of bacteria, and microbiological assays—topics unique to microbiology and bioremediation.

A technical and regulatory guidance document is being produced and will be completed in early 2008. The guidance focuses on the scientific and engineering challenges with DNAPL remediation as well as regulatory concerns. An associated internet training on the guidance document will be available in 2008.