THE EFFECT OF BACTERIAL GENERATION ON THE TRANSPORT OF RADIONUCLIDE IN POROUS-MEDIA

The purpose of this paper is to provide a methodology to develop a pre dictive model based on a conceptual three-phase system and to investig ate the influence of bacteria and their generation on the radionuclide transport in porous media. The mass balance equations for bacteria, s ubstrate and radionuclide were formulated. To illustrate the model sim ply, an equilibrium condition was assumed to partition the substrate, bacteria and radionuclide concentrations between the solid soil matrix , aqueous phase and bacterial surface. From the numerical calculation of radionuclide transport in the presence of bacteria, it was found th at the growth of bacteria and supplied primary substrate as a limiting or stimulating growth factor of bacteria are the most important facto rs of the radionuclide transport. It was also found that, depending on the transport of bacteria, the temporal and spatial distribution of t he radionuclide concentration was significantly affected. The model pr oposed in this study will improve the evaluation of the role of the ba cteria to the transport of radionuclide in groundwater systems, Furthe rmore, this model can be usefully utilized in analyzing the important role of colloidal particulate on the overall performance of radioactiv e waste safety. (C) 1997 Elsevier Science Ltd.