Decontamination of Biological Threats in Water Supplies

Summary

The availability of safe pure drinking water in the United States is taken for granted. The presence of dangerous microorganisms, viruses and toxins in our water systems can result in death, damage to health, and loss of public trust in our government to protect them. Detection of biological threats in water systems is difficult because small amounts can cause disease and similar, but not dangerous, organisms are present in the environment. This project, funded by the EPA's National Homeland Security Research Center, was to study a range of biological contaminants, measure the extent of the contamination and to develop methods to decontaminate building water systems.

Description

The outcome of the project was to provide the EPA with a technical resource document that could be used to guide emergency responders and for longer-term microbial decontamination of building water systems. This project was done in collaboration with the Building and Fire Research Laboratory (BFRL). Researchers in the BFRL also studied the detection and decontamination of dangerous chemicals in building water systems. The research was done on small bench-scale pipe systems and also on a large-scale system designed to simulate a multi-floor building water system. Model water systems were developed to establish biofilms, the naturally occurring microorganisms that form on the surfaces of water systems. Simulants for the real biological threats were developed based on the similar biological and chemical properties. The simulant used for Bacillus anthracis spores (that cause the disease anthrax) was Bacillus thuringiensis spores (a harmless material used for insect control). Strains of E. coli were used for other dangerous bacteria. Model proteins (enzymes) were also developed for the protein toxin ricin. Small-scale experiments were done with bacteria and protein toxins in the biosafety level 2 laboratories. The large-scale experiments were done with the harmless simulants developed in the project. The adhesion and disinfection of the biological threats to the model water systems was measured over a variety of conditions. Different concentrations of the commonly used disinfectants, chlorine and monochloramine, were used to study the disinfection process. A novel disinfection process was developed using conditions to stimulate the germination of Bacillus spores resulting in improved disinfection in the water systems.

Major Accomplishments

• Provided the EPA with data on the adhesion of biological threats (spores, bacteria, and toxins) to water systems and recommendations for the decontamination of the water systems.
• Developed a novel method to increase the disinfection of Bacillus spores based on germination.
• Communicated results to the EPA and responder community with presentations, reports, and publications.

Associated Publications:

Cole, K. D.; Gaigalas, A.; Almeida, J. L., Process Monitoring the Inactivation of Ricin and Model Proteins by Disinfectants using Fluorescence and Biological Activity. Biotechnology Progress 2008, 24, 784-791.

Treado, S.; Kedzierski, M.; Flynn, D.; Wilmering, D.; Montgomery, T.; Cole, K., Contaminant Accumulation and Removal in Building Plumbing Systems. NIST Technical Note 1605 2008, U.S. Department of Commerce, Washington, D.C.

Morrow, J. B.; Almeida, J. L.; Fitzgerald, L. A.; Cole, K. D., Measurement and Decontamination of Bacillus spores in a simulated drinking water system. Water Research (in press).

Morrow, J. B.; Cole, K. D., Enhanced Decontamination of Bacillus spores in a Simulated Drinking Water System by Germinate Addition, submitted.