Field Study of Biostimulation and Bioaugmentation for Remediation of Tetrachloroethene in Groundwater

摘要

A 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 pilotstudy 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 down-gradient 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.