Reactor Wall Reflections Impact Dose Delivery And Regulatory Compliance With UV Disinfection

摘要

MS2 RED predicted using Computational Fluid Dynamics (CFD)-based ultraviolet (UV) dose models was compared to MS2 REDs measured and predicted using the UV validation of two commercial UV reactors. The UV output used to predict intensity used by the UV dose model was calibrated by the comparison of measured and predicted UV sensor readings. The comparison indicates that the reflection of UV light has a significant contribution to UV dose delivery with operation of the UV reactor at high water UV transmittance. If UV reflectance decreases over time with operation of the reactor at the water treatment plant, the UV reactor's dose-monitoring algorithm developed using validation data could significantly over predict dose delivery by the reactor. This issue can be dealt with by the application of a safety factor based on CFD models, by UV validation with walls coated to absorb UV light, or by a monitoring algorithm that measures and accounts for UV reflection.