Abstract: A system of deactivating microorganisms in water involves illuminating the microorganisms using at least one short-duration, high-intensity pulse of broad-spectrum polychromatic light. The system includes a watertight housing having an inlet port and an outlet port for the flow water. A tubular light source for deactivating microorganisms and a tubular baffle for directing the water flow are positioned within the watertight housing. Waters enters the inlet port and flows between the watertight housing and the tubular baffle in one direction, around the end of the tubular baffle and back through the center of the tubular baffle in a second direction exiting the outlet port. In one embodiment, the inlet and outlet ports are positioned at the same end of the watertight housing. In a another embodiment, the inlet port is at the end of the watertight housing and the outlet port extends radially from the tubular baffle through the side of the watertight housing.

Abstract: A method of deactivating microorganisms in food products, packaging material, water, air, and other products involves illuminating the microorganisms using at least one short-duration, high-intensity pulse of broad-spectrum polychromatic light. In variations of this embodiment, the light has an intensity of at least 0.1 J/cm.sup.2, the pulse duration is from between about 10 nanoseconds and 10 milliseconds, and/or at least 50% of the at least one pulse's energy is transmitted in light having wavelength from between about 170 and 2600 nanometers. Advantageously, the microorganisms may be Cryptosporidium parvum oocysts, Bacillus pumilus spores or poliovirus.