BY JAMES J. LIDINGTON

Two Old Dominion researchers believe they have found a cheaper, more effective way to kill harmful microorganisms that are being spread into the Chesapeake Bay and other coastal waters by ships from overseas.

Mounir Laroussi, an electrical engineering research professor, and Fred Dobbs, associate professor of oceanography, have developed a technique using a concentrated type of ultraviolet (UV) light to kill the organisms found in ballast water within the hulls of cargo ships.

Funded by a grant from the National Seagrant College Program of the National Oceanic and Atmospheric Administration, they created a reactor built around a specially designed UV lamp. To date, tests have been conducted using a table-top prototype, which needs only to be plugged into an ordinary wall outlet.

The device's electrical power consumption is relatively low - less than 300 watts per lamp - and the light source can be produced for about $7,000, compared to more powerful but less productive sources that cost five times that amount.

Kill rates achieved by the reactor are equal to or better than those in other known UV systems, according to Dobbs. Tests have been performed on organisms, including E.coli and hard-to-kill forms of Bacillus subtilis and dinoflagellates, all of which perished in the UV light.

Dobbs and Laroussi believe the system could be used in any water treatment application: drinking water processing; water and sewage treatment; decontamination of waste water; decontamination of waste water from the animal-production industry; and chiller water for the food and meat processing industries.

Dobbs co-authored an article in the Nov. 2 issue of the journal Nature, describing how ballast water in the hulls of cargo ships traveling around the world is spreading harmful bacteria (see story below).