AWWA ACE59838

The ultraviolet (UV) dose delivered by a UV disinfection system can be predicted by computational fluid dynamics (CFD) and UV intensity models for varying UV transmittance (UVT), inactivation kinetics and system operating conditions. This study involved CFD modeling to evaluate the effect of these factors on the reduction equivalent dose (RED) and RED bias of two UV system designs. The RED bias is a correction factor that accounts for differences in the RED for the challenge microbe used during reactor validation and the target pathogen RED. Results indicate that RED bias significantly decreases as the UVT increases and as the UV sensitivity of the challenge microbe approaches that of the target microbe. Results also demonstrate that RED bias varies from reactor to reactor. Includes 10 references, table, figures.