Technology takes aim at viruses

Researchers at the University have developed an inexpensive, nonchlorine-based technology that can remove harmful microorganisms, including viruses, from drinking water.

The patented technology, developed jointly by researchers in the College of Agriculture and Natural Resources and the College of Engineering, incorporates highly reactive iron in the filtering process to deliver a chemical “knock-out punch” to a host of notorious pathogens, 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), more than a billion people, or one-sixth of the world’s population, lack access to safe water supplies.

Four billion cases of diarrheal disease occur worldwide every year, resulting in 1.8 million deaths, primarily infants and children in developing countries. Eighty-eight percent of this disease is attributed to unsafe water supplies, inadequate sanitation and hygiene.

In the United States, viruses are the target pathogenic microorganisms in the new Ground Water Rule under the Environmental Protection Agency’s Safe Drinking Water Act, which took effect Jan. 8.

“What is unique about our technology is its ability to remove viruses—the smallest of the pathogens—from water supplies,” Pei Chiu, associate professor of civil and environmental engineering, says.

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 byproducts in our drinking water, and at an acceptable cost,” Chiu says.

Viruses are difficult to eliminate in drinking water using current methods because they 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.

Of all the inhabitants of the microbial world, viruses are the smallest—as tiny as 10 nanometers. According to the American Society for Microbiology, if a virus could be enlarged to the size of a baseball, the average bacterium would be the size of the pitcher’s mound, and a single cell in your body would be the size of a ballpark.

“By using elemental iron in the filtration process, we were able to remove viral agents from drinking water at very high efficiencies,” Chiu says. “Of a quarter of a million particles going in, only a few were going out.”

The elemental iron used in the technology is widely available and inexpensive.

The idea for the UD research sprang up when Jin and Chiu were discussing their respective projects over lunch one day.

Since joining UD in 1995, Jin’s primary research area has been investigating the survival, attachment and transport behavior of viruses in soil and groundwater aquifers. One of the projects, which was sponsored by the American Water Works Association Research Foundation, involved testing virus transport potential in soils collected from different regions across the United States. Jin’s group found that the soils high in iron and aluminum oxides removed viruses much more efficiently than those that didn’t contain metal oxides.

“We knew that iron had been used to treat a variety of pollutants in groundwater, but no one had tested iron against biological agents,” Chiu says. So the two researchers decided to pursue some experiments.

With partial support from the U.S. Department of Agriculture and the Delaware Water Resources Center, through its graduate fellowship program, 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.

Since then, Kniel has been documenting the technology’s effectiveness against such human pathogens as E. coli 0157:H7, hepatitis A, norovirus and rotavirus. Rotavirus is the leading cause of diarrhea in children, according to Kniel.

“In 20 minutes, we found 99.99 percent removal of the viruses,” Chiu says. “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 naturally occurs in groundwater and other sources of drinking water.

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 says.

“Our hope is that the technology we’ve developed will help people in our country and around the world, especially in developing countries,” Jin says.

—Tracey Bryant