Kinetics and Modeling of Reductive Dechlorination at High PCE and TCE Concentrations Seungho Yu, Lewis Semprini Department of Civil, Construction, and Environmental Engineering, Oregon State University, Corvallis, Oregon 97331; telephone: 541-737-6895; fax: 541-737-3099; e-mail:
[email protected] Received 26 March 2004; accepted 8 July 2004 Published online 21 September 2004 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/bit.20260 Abstract: Two biokinetic models employing the Michaelis- INTRODUCTION Menten equation for anaerobic reductive dechlorination of tetrachloroethylene (PCE) and trichloroethylene (TCE) Chlorinated ethylenes are ubiquitous soil and groundwater were developed. The models were compared with results contaminants (Westrick et al., 1984), for which bioreme- from batch kinetic tests conducted over a wide range of diation is a promising technology. Anaerobic reductive de- PCE and TCE concentrations with two different dechlorin- chlorination is an important process in the subsurface, ating cultures. One model applies Michaelis-Menten ki- netics with competitive inhibition among chlorinated especially for the dechlorination of highly chlorinated com- aliphatic hydrocarbons (CAHs), while the other model in- pounds such as PCE and TCE, which can be present at high cludes both competitive inhibition and Haldane inhibition concentrations due to the presence of dense non-aqueous at high CAH concentrations. Model simulations with com- phase liquid (DNAPL; Rittmann et al., 1994). petitive inhibition simulated the experimental results well Although intrinsic biotransformation of PCE and TCE for PCE concentrations lower than 300 AM. However, sim- ulations deviated from the experimental observations for occurs, observations at many contaminated sites show trans- PCE or TCE concentrations greater than 300–400 AM.