Field study of biostimulation and bioaugmentation for remediation of tetrachloroethene in groundwater

Abstract

AbstractA pilot field study was conducted for remediation of a tetrachloroethene (PCE)‐contaminated site in Manhattan, Kansas. Prior to the pilot study, the PCE concentration in groundwater at the pilot‐study area was about 15 mg/L (91 µM). Nutrient solution comprising soy oil methyl esters (SOME), lactate, and yeast extract was added in the pilot‐study area for biostimulation on August 18, 2005 (day 0). Potassium bromide (KBr) was added in the nutrient solution as a tracer. PCE was converted to dichloroethene (DCE) under these conditions. KB‐1, a consortium of Dehalococcoides, and a second dose of nutrient solution were added on day 56. After addition of KB‐1, both PCE and DCE concentrations decreased. Nutrients were again injected on day 197 (with KBr). On day 348, cheese whey was injected. Soluble nutrients and KB‐1 migrated downstream, affecting PCE and DCE concentrations at downgradient wells; however, KB‐1 moved slower than the aqueous phase. The total chlorinated ethenes (CEs) decreased by about 80 percent in the pilot‐study area due to bioremediation. Biodegradation of CEs continued for several months after the addition of nutrients. A portion of the insoluble SOME was retained in the vicinity of the injection wells and provided a long‐time source of nutrients and electron donors that supported degradation of PCE. A mixture of SOME and soluble substrates worked effectively in this study. © 2011 Wiley Periodicals, Inc.