Integrated Field, Laboratory, and Modeling Studies to Determine the Effects of Linked Microbial and Physical Spatial Heterogeneity on Engineered Vadose Zone Bioremediation

Brockman, Fred ; Selker, John

Pacific Northwest National Laboratory (U.S.)

关键词: Removal;    Transport;    Bioremediation;    59 Basic Biological Sciences;    Simulation;   

DOI  :  10.2172/833634
RP-ID  :  EMSP-70165--2002
RP-ID  :  FG07-99ER62887
RP-ID  :  833634

美国|英语

来源: UNT Digital Library

【 摘 要 】

In situ bioremediation of contaminants can offer advantages in cost, speed, public acceptance, and final cleanup levels achieved relative to physical removal methods. However, microbial populations in the unsaturated zone are spatially discontinuous and sparse, especially in deep vadose zones and in arid climates with very low moisture and nutrient flux. In addition, there is a lack of knowledge on (1) the ability of microbes to colonize ''empty'' regions of the vadose zone in response to nutrient delivery and (2) how microbial colonization is controlled by hydrologic and physical features. These issues raise questions about the feasibility of deep vadose zone bioremediation and the accuracy of flow and transport models for vadose zone bioremediation. The goal of this research is to provide DOE with an increased understanding of the effect of interacting hydrologic and microbiological processes that control the feasibility of engineered bioremediation of chlorinated compounds in heterogeneous, microbially sparse deep vadose zones. The specific objectives are: (1) to conduct laboratory research on vadose zone microbial colonization processes as a function of hydrologic and physical features, and use the information to develop an improved vadose zone reactive transport model; (2) to evaluate a gas-phase nutrient delivery approach for enhancing removal of carbon tetrachloride from the vadose zone. Research Progress and Implications This report summarizes the progress achieved during 2.5 years of a 3-year project. Research tasks under way at Pacific Northwest National Laboratory are addressing the ability of microbes to colonize uninhabited porous media under static unsaturated conditions. At Oregon State University, researchers are examining the dynamics of microbial metabolic and colonization processes under flowing unsaturated conditions. Both efforts involve understanding how microbial colonization is controlled by porous media water content and particle size.