Dec 28, 2000

UNC-CH Experiments Reveal New 'Pen' Disinfects Water

Chemical disinfectants such as chlorine and fuels to boil water often are unavailable for disinfecting drinking, cooking and washing water.

To help solve the problem, researchers have developed a battery-powered disinfecting "pen," which is approximately seven inches long and weighs four ounces. The device electrochemically generates mixed oxidants from a salt solution that individuals can use to purify drinking water.

Investigators evaluated the new battery-powered tool to see how well it inactivated waterborne parasites, viruses and bacteria. Several alternative pen cell designs also were tested by seeding oxidant solutions generated from the pen with test microbes, including highly chlorine-resistant Cryptosporidium parvum, a major source of contamination in water. "There was dramatic—more than 99.99 percent—reduction of all test bacteria and viruses within one to 10 minutes," Sobsey said. "Considerable inactivation of Cryptosporidium parvum was also achieved within 90 minutes."

Experiments demonstrated that the miniature pen cell electrochemically generated a mixture of oxidants from a salt solution that was able to inactivate Cryptosporidium parvum eggs, as well as bacterial spores, bacteria and viruses to produce safer drinking water in minutes, he said.

"The pen cell makes it possible for people to easily and quickly have safe supplies of personal drinking water in remote and isolated areas and during situations where water supplies are at risk of being contaminated," Sobsey said.

Users put a small amount of water into the pen, and then salt pellets dissolve in the water, which comes in contact with battery-powered
electrodes, he explained. Within 30 or so seconds of flicking a switch, a chemical reaction known as electrolysis generates chlorine and other oxidants from the saltwater. "The solution contents are then added to a quart bottle of water or a canteen," Sobsey said. "This delivers enough oxidants to disinfect the water in 10 minutes even better than plain chlorine does."

Tests of the invention took place at the University of North Carolina at Chapel Hill's Environmental Health Microbiology Laboratories. Dr. Mark D. Sobsey, professor of environmental sciences and engineering at the UNC-CH School of Public Health, led the effort with doctoral students Maren E. Anderson and Julie A. Kase. Los Alamos Technical Associates and MIOX Corp. of Albuquerque developed the pen, and the latter funded the UNC-CH research. Results of the independent analysis are being presented at a news conference at the 100th annual general meeting of the American Society for Microbiology in Los Angeles Wednesday (May 24).

(Source: University of North Carolina-Chapel Hill News Services, David Williamson)