New technology removes viruses from drinking water.

University of Delaware (UD) researchers have developed an inexpensive, non-chlorine-based technology that can remove harmful microorganisms, including viruses, from drinking water. UD's patented technology incorporates highly reactive iron in the filtering process to deliver a chemical "knock-out punch" to pathogens ranging from E. coli to rotavirus.

The new technology could dramatically improve the safety of drinking water around the globe, particularly in developing countries. According to the World Health Organization (WHO), over a billion people--one-sixth of the world's population--lack access to safe water supplies. In the United States, the new Ground Water Rule of the U.S. Environmental Protection Agency's Safe Drinking Water Act, which took effect on January 8, 2007, targets viruses.

"What is unique about our technology is its ability to remove viruses--the smallest of the pathogens--from water supplies," said Pei Chiu, an associate professor in UD's Department of Civil and Environmental Engineering.

Chiu collaborated with Yan Jin, a professor of environmental soil physics in UD's plant and soil sciences department, to develop the technology. They then sought the expertise of virologist Kali Kniel, an assistant professor in the animal and food sciences department, who has provided critical assistance with the testing phase.

"A serious challenge facing the water treatment industry is how to simultaneously control microbial pathogens, disinfectants such as chlorine, and toxic disinfection by-products in our drinking water--and at an acceptable cost," Chiu noted.

With current methods, it is difficult to eliminate viruses in drinking water because viruses are far smaller than bacteria, highly mobile, and resistant to chlorination, which is the dominant disinfection method used in the United States, according to the researchers.

The elemental, or "zero-valent," iron (Fe) used by the UD researchers is widely available as a by-product of iron and steel production, and it is inexpensive, currently costing less than 40 cents a pound (~$750 a ton). Viruses are either chemically inactivated by or irreversibly adsorbed to the iron, according to the scientists.

With partial support from the U.S. Department of Agriculture and the graduate fellowship program of the Delaware Water Resources Center, the scientists and their students began evaluating the effectiveness of iron granules in removing viruses from water under continuous-flow conditions and over extended periods. Two bacteriophages--viruses that infect bacteria--were used in the initial lab studies.

Since then, Kniel has been documenting the technology's effectiveness against human pathogens, including E. coli 0157:H7, hepatitis A, norovirus, and rotavirus. Rotavirus is the number-one cause of diarrhea in children, according to Kniel.

"In 20 minutes, we found 99.99 percent removal of the viruses," Chiu said. "And we found that removal of the viruses got even better than that with time, to more than 99.999 percent."

The elemental iron also removed organic material, such as humic acid, that occurs naturally in groundwater and other sources of drinking water. During the disinfection process, this natural organic material can react with chlorine to produce a variety of toxic disinfection by-products.

"Our iron-based technology can help ensure drinking-water safety by reducing microbial pathogens and disinfection by-products simultaneously," Chiu noted.

Besides helping to safeguard drinking water, the UD technology may have applications in agriculture. Integrated into the wash water system at a produce-packing house, it could help clean and safeguard fresh and ready-to-eat vegetables, particularly leafy greens like lettuce and spinach, as well as fruit, according to Kniel.

"Sometimes on farms, wash water is recirculated, so this technology could help prevent plant pathogens from spreading to other plants," she added.

The University of Delaware is pursuing commercialization opportunities for the technology. Patents have been filed in the United States, Canada, France, Germany, and Switzerland. For more information, contact Bruce Morrissey, UD director of technology development, at [e-mail] or [phone].