The novel “microsphere dosimeter” technique is the first direct test of how much UV light microorganisms in fluids have been exposed to, say the researchers - a critical step in validating the use of UV light treatment for preventing the spread of infection through drinking water. The technique uses fluorescent microspheres, which become bleached with exposure to UV light, to mimic pathogenic microbes in water flowing through a UV reactor. By measuring the bleaching of the microspheres, the researchers can obtain precise measures of the full distribution of UV doses that a pathogen may experience - information critical for gauging the treatment's capacity to kill disease-causing bacteria or parasites before they reach the public.
The new method comes at a key time as the Environmental Protection Agency (EPA) is set to introduce regulations in requiring water treatment plants at risk of infection to add UV reactors as an additional line of defense against pathogenic contaminants in the water supply.