Characterization of the Aerobic Oxidation of Cis-Dichloroethene and Vinyl Chloride in Support of Bioremediation of Chloroethene-Contaminated Sites

Download or read book Characterization of the Aerobic Oxidation of Cis-Dichloroethene and Vinyl Chloride in Support of Bioremediation of Chloroethene-Contaminated Sites written by and published by . This book was released on 2004 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: The lesser chlorinated ethenes, cis-1,2-dichloroethene (cDCE) and vinyl chloride (VC), are produced by anaerobic reductive dechlorination at subsurface sites contaminated by tetrachloroethene (PCE) and trichloroethene (TCE). Accumulation of VC and cDCE under anaerobic conditions limits the application of natural attenuation and enhanced reductive anaerobic biological in-situ treatment technologies (RABITT). Aerobic degradation of lesser chlorinated ethenes has been demonstrated, suggesting that sequential anaerobic/aerobic conditions may result in complete mineralization of PCE/TCE. However, our present understanding of the aerobic transformation potentials of cDCE and VC is limited, thus limiting the reliability of and confidence in natural and enhanced biological alternatives for site remediation. The objective of our project was to determine the prevalence and metabolic capabilities of microorganisms able to derive energy from aerobic oxidation of cDCE and/or VC in subsurface environments. The results help delineate the role of growth-coupled (vs. cometabolic) aerobic oxidation in the natural attenuation of lesser-chlorinated ethenes. Results provide the basis for improved site assessment, improved remedial-action decision-making, and more reliable bioremediation technologies. Our findings indicate that aerobic bacteria (Mycobacterium and Nocardioides strains) capable of growth-linked VC oxidation are widespread in the environment, and commonly found at chlorinated-ethene-contaminated sites. Aerobic assimilation of VC as a carbon source is therefore an ecologically significant phenomenon of equal or greater importance than cometabolic VC degradation. Based on their distribution, growth rates and kinetic parameters, we believe that Mycobacterium strains are most likely to be responsible for the aerobic natural attenuation of VC that has been observed at many sites.