Date of Graduation
Statler College of Engineering and Mineral Resources
Civil and Environmental Engineering
Jennifer L Weidhaas
Radhey S. Sharma
Trichloroethylene (TCE) released to the environment is of great concern due to its toxicity and carcinogencity. The microorganisms involved in bioremediation of TCE such as methanogens (organisms within the domain Archaea), sulfate reducing bacteria (SRB) and Dehalococcoides sp. (DHC) are of particular interest in this study. Three different types of bench scale reactors were constructed to model different aquifer types such as sandy, silty and fractured bedrock aquifers (hereafter type 1, 2 or 3 reactors, respectively). This study evaluated the effect of TCE concentration in different types of reactors on the distribution of selected microorganisms with distance from the source of the TCE. It also examined the spatial relationship between Dehalococcoides sp., Archaea and SRB with respect to reducing equivalents (e.g., food) in different types of aquifer environment contaminated with TCE. The DNA analysis was performed by using quantitative polymerase chain reaction (qPCR) and fluorescent in situ hybridization (FISH). In this study concentrations of Archaea were higher in all reactors than other microorganisms under study. In the type 1 reactor, with increasing concentrations of TCE, DHC concentrations and SRB concentrations increased. In type 2 and 3 reactors, there were no observed correlations between initial concentrations of TCE and the concentration of the studied microbes. The highest DHC concentration was present near the food source in type 1 and 2 reactors. In type 3 reactors the concentration of microorganisms was higher outside the tube (e.g., fracture) than inside. The spatial relationship between Dehalococcoides sp. and various microorganisms that compete for bioremediation substrates supplied is helpful to understand when and where to bioaugment an aquifer undergoing bioremediation of TCE with Dehalococcodies sp.
Gautam, Pujya Wagle, "Spatial Relationship between the Trichloroethylene Degrading Bacteria Dehalococcoides Sp., Sulfate Reducers and Archaea during Reductive Dechlorination" (2013). Graduate Theses, Dissertations, and Problem Reports. 580.