CULTURE DEVELOPMENT FROM A DNAPL ZONE FOR DECHLORINATION OF
1,1,1-TCA & TCE IN HIGH CONCENTRATIONS
George Pon, Ph.D. (G.Pon@BioTreatCenter.com) (Bioremediation & Treatability Center, Walpole, Massachusetts, USA)
Sami A. Fam, Ph.D., P.E. L.S.P., Stewart Mountain, P.E., L.S.P., and
David Falatko, P.E.,
(Innovative Engineering Solutions, Inc., Walpole, Massachusetts, USA)
Bioremediation of a mixture of 1,1,1-trichloroethane (TCA) and trichloroethene (TCE) is much more challenging than bioremediation of tetrachloroethene (PCE) and trichloroethene (TCE) series compounds. In this study, we developed a mixed-culture originated from a TCA source zone. In its natural environment, the culture also tolerated very high concentrations of TCE, cis-1,2 -DCE (hundreds of ppm). Results showed that this mixed culture dechlorinated high concentrations of TCA, through 1,1-dichloroethane (DCA) to chloroethane (CA). That is, it could dechlorinate TCA at concentrations up to 600 ppm (with difficulty), but is routinely grown on 200 ppm of TCA. In addition to its TCA dechlorination capability, this consortium can also degrade high concentration of PCE and TCE. Interestingly, microbes in this culture showed activity on dechlorinating low levels of chloroform through dichloromethane to chloromethane.
Our historical experience had indicated that TCA biodegradation microbes is concentration sensitive, with inhibition concentrations starting at ~35-70 ppm unless with bioaugmentation of this NJ-14 variant culture (called NJ-14-5). This study has increased the inhibition limitation to 200 ppm. We have seen this limitation extended at two of our project sites where TCA concentrations are in the 200 ppm range. Detailed inhibition studies on TCE and cis-DCE will also be discussed with the help of preliminary genetic testing results. A practical attempt to grow this culture on TCE NAPL to enhance TCE NAPL dissolution is also in progress.
