Biodegradation of Dense Non-Aqueous Phase Liquids (DNAPLs) Through Bioaugmentation of Source Areas Dover National Test Site, Dover, Delaware

This demonstration evaluated the use of biological processes to enhance the dissolution of a tetrachloroethene PCE from an aquifer known to have PCE present in a dense non-aqueous phase liquid DNAPL form. There are no currently available, proven technologies that can reliably remove 100 of DNAPL both free product and residual mass. There is a critical need for technologies that can effectively treat DNAPL sources in the saturated zone, resulting in both destruction and containment with reduced treatment times and lower costs. The approach of this demonstration was to introduce naturally-occurring, dehalo-respiring microbial consortia that function at the solubility limits of chlorinated solvents, into DNAPL source areas. Bioaugmentation is an in-situ remediation approach where complete dechlorination of chlorinated ethenes is stimulated by supplying microorganisms that have demonstrated the ability to completely dechlorinate chlorinated ethenes in the presence of the appropriate electron donors and nutrients. The objective is for the microorganisms to enhance rates of biodegradation at the DNAPL-to-water interface thereby increasing the concentration gradient driving DNAPL dissolution. Increasing the concentration gradient will result in more rapid DNAPL dissolution and a reduction in the time required for cleanup. In summary this demonstration was successful and was able to prove that biological systems can be applied and promote enhanced dissolution of a PCE DNAPL.