Pen-shaped device purifies water

From Los Angeles, at the annual meeting of the American Society for Microbiology

Portable water-purification device alongside a ballpoint pen. Miox

Is the pen mightier than the microbe? That’s the question Mark D. Sobsey sought to answer for Miox Corp. in Albuquerque.

The firm, which specializes in large-scale water-purification technology, asked Sobsey’s research team at the University of North Carolina at Chapel Hill to evaluate whether its new battery-powered, pen-shaped device can quickly rid water of harmful bacteria, viruses, and other microbes. Miox hopes the simple, lightweight instrument will prove useful to soldiers, campers, international travelers, disaster victims, and anyone else needing to clean up their drinking water.

Sobsey and his colleagues have found that the pen lives up to its billing, at least in initial tests. The device is simple to use: A small amount of water poured into the top dissolves a salt tablet to produce brine. A twist of the pen sends electricity through the solution, creating highly reactive molecules called mixed oxidants. The user then pours the activated brine into a liter or two of water.

Sobsey’s group tested Miox’s device on water that they had seeded with various disease-causing microbes. Without changing the water’s taste or odor, a drawback of disinfection with chlorine, the mixed oxidants destroyed 99.99 percent of bacteria and viruses in 10 minutes. “Basically, everything we put in there is obliterated,” says Maren E. Anderson, one of Sobsey’s colleagues.

Although it took about 90 minutes, the mixed oxidants also largely purged the water of chlorine-resistant Cryptosporidium parvum. This parasite, which gained public attention in 1993 when it infected hundreds of thousands of people in Milwaukee through their drinking water, can cause severe diarrhea and even kill immune-compromised people.

To gauge how Miox’s instrument will work in the field, Sobsey’s team will next test the purification devices on water samples that vary in qualities such as acidity and particulate matter. The investigators also hope to characterize the mixed oxidants that are so lethal to the microbes. “We don’t yet know the active species,” says Anderson.