Use of a mathematical model for prediction of optimum feeding strategies for in situ bioremediation

Liquid wastes containing radioactive, hazardous, and regulated chemicals have been generated throughout the 40+ years of operations at the US Department of Energy (DOE) Hanford site. Some of these wastes were discharged to the soil column and many of the waste components, including nitrate, carbon tetrachloride (CCL{sub 4}), and several radionuclides, have been detected in the Hanford groundwater. Current DOE policy prohibits the disposal of the contaminated liquids directly to the environment, and remediation of the existing contaminated groundwaters may be required. In-situ bioremediation is one technology currently being developed at the Hanford to meet the need for cost effective technologies to clean groundwater contaminated with CCL{sub 4}, nitrate, and other organic and inorganic contaminants. This paper focuses on the latest results of an on-going effort to develop effective in-situ remediation strategies through the use of predictive simulations. In particular, strategies for nutrient injection are developed which minimize biomass accumulation within the flow field and thus extend the life of injection wells.