Microbial Pathogen Removal During Bank FiltrationEPA Grant Number: R829010
Title: Microbial Pathogen Removal During Bank Filtration
Investigators: Ryan, Joseph N. , Harvey, Ronald W. , Elimelech, Menachem
Institution: University of Colorado at Boulder , United States Geological Survey , Yale University
EPA Project Officer: Page, Angela
Project Period: September 1, 2001 through August 31, 2004 (Extended to August 30, 2005)
Project Amount: $506,006
RFA: Drinking Water (2000) RFA Text | Recipients Lists
Research Category: Drinking Water , Water
Our incomplete understanding of processes and properties affecting pathogenic microbe transport during riverbank filtration is currently limiting our ability to predict the effectiveness of this water treatment option. We propose a series of fundamental experiments designed to better understand the effects of microbe size, physical and geochemical heterogeneity of the porous media, and high pumping rates on the transport of Cryptosporidium parvum oocysts and Giardia lamblia cysts in alluvial valley aquifers used for riverbank filtration.
Hypotheses to be tested during this research address (1) the effect of microbe size on transport, (2) the effect of physical heterogeneity of the porous media on transport, (3) the effect of geochemical heterogeneity of the porous media on transport, (4) the effect of microbe release from unfavorable attachment sites, and (5) the effect of high pumping rates on microbe release. Our major objective for this research is to develop a model of oocyst transport in porous media that can accommodate the physical and geochemical heterogeneity present in alluvial valley aquifer used for riverbank filtration.
The experiments will be conducted in flow-through columns and an intermediate-scale two-dimensional aquifer tank (10 m length, 1.5 m height). The porous media to be used in the column and tank experiments will be designed to simulate the complex and variable stratigraphies and geochemical gradients encountered in alluvial valley aquifers. Column experiments will be used to explore the effects of grain-scale heterogeneities on microbe transport and to provide data for modeling of the intermediate-scale tank experiments. The tank experiments will be used to examine layered and random heterogeneities above the grain scale. We have proposed laboratory column and tank experiments to investigate microbe transport during riverbank filtration because some of the fundamental processes affecting microbe transport in porous media still need to be better understood. These experiments will be carefully controlled and reproducible, yet still representative of riverbank filtration conditions.
Results from the column and tank experiments will be used to develop and test a two-dimensional model of microbe transport in geochemically and physically heterogeneous porous media. Once tested against the results of the tank experiment, this model will be capable of generating estimates of Cryptosporidium parvum oocysts and Giardia lamblia cysts removal during riverbank filtration.