AWWA WQTC64088

Ultraviolet (UV) water disinfection systems employing excimer lamp technology represent a suitable choice in situations where lamp mercury content is restricted, or otherwise undesirable. Excimer lamps exist that generate germicidal UV radiation with appropriate electrical efficiency, and at relevant wavelengths in terms of germicidal effectiveness and water transmittance. In conjunction with NASA's interests in conducting long-duration human space missions, where severe restrictions on mercury are evident, a UV system was designed based on XeBr* excimer lamp technology. XeBr* excimer lamps emit nearly monochromatic radiation at a characteristic wavelength of 282 nm. Baseline experiments conducted with a XeBr* excimer lamp demonstrated its germicidal UV output to be highly effective for inactivation of Bacillus subtilis spores. A numerical prototype of this new reactor system was developed using a Lagrangian modeling scheme. The modeling approach involved simulation of fluid mechanics and particle trajectories using commercially available computational fluid dynamics software (FLUENT). Accurate simulations of the radiation intensity field within the reactor required the development of a new intensity field model. The final design of the reactor was produced by an iterative procedure using these modeling tools, thereby allowing for optimization of reactor characteristics. Simulations of the behavior of the numerical prototype indicated high efficiency, in terms of microbial inactivation and power consumption. Includes 9 references, figures.