AWWA WQTC64138

AWWA WQTC64138 Validation of Large-Scale, Monochromatic UV Disinfection Systems Using Dyed Microspheres
Conference Proceeding by American Water Works Association, 11/01/2006

Blatchley, E.R., III; Shen, C.; Scheible, O.K.; Robinson, J.P.; Ragheb, K.; Bergstrom, D.E.; Rokjer, K.

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Dyed microspheres have been developed as a new approach for validation of ultraviolet (UV) reactorsystems. When properly applied, dyed microspheres allow for measurement of the UV dose distributiondelivered by the reactor for a given operating condition. Prior to this research, dyed microspheres hadonly been applied to a bench-scale UV reactor. The goal of this research was to extend the application ofdyed microspheres to large-scale reactors.Dyed microsphere tests were conducted on two large-scale UV reactors at the UV Validation andResearch Center of New York (UV Center) in Johnstown, NY. All microsphere tests were conductedunder conditions that had been used previously in biodosimetry experiments involving two challengephage: MS-2 and Q. Numerical simulations based on computational fluid dynamics and irradiance fieldmodeling were also performed for the same set of operating conditions used in the microspheres assays.Microsphere tests on the first reactor illustrated difficulties in sample collection and discrimination ofmicrospheres against ambient particles. Changes in sample collection and work-up were implemented intests conducted on the second reactor that allowed for improvements in microsphere capture anddiscrimination against the background. Under these conditions, estimates of the UV dose distributionfrom the microspheres assay were in good agreement with numerical simulations and the results ofbiodosimetry, using both challenge organisms.The combined application of dyed microspheres, biodosimetry, and numerical simulation offers thepotential to provide a more in-depth description of reactor performance than any of these methodsindividually, or in other combinations. This approach has the potential to substantially reduceuncertainties in reactor validation, thereby leading to better understanding of reactor performance, and thedevelopment of more efficient reactor designs. Includes 19 references, tables, figures.