Virus Attachment, Release, and Inactivation During Groundwater TransportEPA Grant Number: R826179
Title: Virus Attachment, Release, and Inactivation During Groundwater Transport
Investigators: Ryan, Joseph N. , Harvey, Ronald W. , Elimelech, Menachem
Institution: University of Colorado at Boulder , United States Geological Survey [USGS] , University of California - Los Angeles
EPA Project Officer: Lasat, Mitch
Project Period: January 13, 1998 through January 12, 2001 (Extended to January 12, 2002)
Project Amount: $372,392
RFA: Exploratory Research - Environmental Chemistry (1997) RFA Text | Recipients Lists
Research Category: Water , Land and Waste Management , Air , Safer Chemicals
The EPA is developing the Ground Water Disinfection Rule (GWDR) to identify public groundwater supply systems vulnerable to contamination by pathogenic microbes. The GWDR will allow treatment variances for water supply systems that can demonstrate adequate "natural disinfection" of viruses in the aquifers. The extent of natural disinfection must be evaluated by models of virus transport; however, current models are based on incomplete understanding of the processes by which viruses are removed from groundwater. The research outlined in this proposal will assist the EPA in better understanding the processes controlling natural disinfection. The following hypotheses will be addressed in this research: (1) organic matter will enhance virus transport in aquifers by adsorbing to positively charged grain surfaces and occupying these favorable attachment sites, (2) the reversibility of virus attachment to aquifer sediments is controlled by heterogeneity of aquifer grains and virus interactions with different mineral and organic matter surfaces, (3) the transport of viruses during long-term release will be enhanced by blocking of favorable attachment sites by attached viruses, and (4) the inactivation of viruses in groundwater is accelerated by strong, irreversible attachment, but not by weak, reversible attachment.
The first task is measure virus attachment and release in static columns and one-dimensional flow-through columns using viruses and minerals that span a range of representative surface chemistries. Because pathogenic viruses will always be introduced to aquifers in the presence of organic matter, variations in the amount and type of organic matter will be emphasized. This task will allow controlled testing of Hypotheses 1, 2, and 3. The second task is to further our understanding of the acceleration of virus inactivation by attachment to mineral surfaces through similar experiments in static columns and flow-through columns. These experiments will focus on a bacteriophage, PRD1, and an animal virus, poliovirus type 1. It is our goal to understand the relationship between the strength and reversibility of virus attachment and the degree of acceleration of inactivation to test Hypotheses 4. The third task is to examine virus transport in the field at the U.S. Geological Survey Cape Cod field site in pulse and continuous injections. The goal of these experiments is to provide virus transport data for model testing in real aquifer sediments. The fourth task is to develop a virus transport model that accounts for the role of organic matter, aquifer grain heterogeneity, dynamics of virus attachment, and surface inactivation in the natural disinfection of viruses and to test this model using the laboratory and field data.
The results of this research will provide better understanding of virus attachment and inactivation mechanisms and better prediction of virus transport for application of the GWDR. By integrated these advances into virus transport models, more accurate predictions of virus travel times will be possible.