AWWA ACE54283

The sensitivity of microorganisms to germicidal ultraviolet (UV) radiation was quantified in a controlled and reproducible manner in order to evaluate the efficacy of commercial UV systems. The ANSI/NSF 55 Standard was used as a guideline for testing the efficacy of four commercial UV units. The evaluation procedure consisted of performing batch UV irradiation experiments utilizing a low-pressure mercury lamp in order to develop a UV dose-response curve for several microorganisms. The microorganisms were then used in a flow-through test facility to challenge the commercial UV units. The inactivation achieved across the UV reactor was quantified and compared to the UV dose-response curve to determine the UV dose delivered by the unit under the flow conditions. The UV units were challenged at the manufacturers rated flow rate withclean quartz sleeves as well as at higher and lower flow rates and under less optimal UV light transmittance conditions. In addition, the UV absorbance of several compounds often found in potential drinking waters was examined through batch experiments utilizing a UV spectrophotometer. Includes tables, figures.



Keywords: Flow;Microorganisms;Ultraviolet Disinfection;Dosage;Adsorption