Progress in the optimization of photosensitized disinfection and decontamination processes using pulsed and CW ultraviolet light sources

Summary form only given. Photosensitized Ultraviolet (UV) treatment is one of the best hopes for achieving the elusive goal of transferring a pulsed power application from the realm of scientific interest to commercial viability. The University of Missouri-Columbia and Clean Earth Technologies, LLC are collaborating on the optimization of photosensitized UV processes for disinfection of surfaces and liquids. Parametric variation has been performed, and an improved comparison of pulsed and CW treatments has been made. The results are reported in this paper. It is found that the photosensitizer interacts differently with plastic, painted, and metal surfaces. Adjustment in the composition and concentrations of the photosensitizer permit a high disinfection efficacy to be obtained. Typically, the process yields more than 6 logs of bioburden reduction of Bacillus subtilis spores on various surfaces and bacteriophage in liquid suspensions.Various treatment modalities are investigated so that pulsed lamps can be compared to a continuous wave, medium pressure mercury-argon lamp baseline. The pulsed lamps include an array of twenty-five short pulse, short arc lamps and two different linear xenon flashlamp systems. Calibration of the UV intensity and measurements of the spectral content are made. Based on the observations, implications about the disinfection mechanisms are inferred.