VALIDATION TESTING OF A UV DISINFECTION SYSTEM TO ACHIEVE REGULATORY APPROVAL FOR WASTEWATER REUSE

In order to respond to the stringent disinfection requirements for reclaimed wastewater in the United States, Infilco Degremont, Inc. (IDI) undertook a validation study of its Aquaray® 40 HO ultraviolet (UV) disinfection system. The disinfection performance of this process technology was verified via biodosimetry in accordance with the Environmental Technology Verification (ETV) Protocol for Secondary Effluent and Water Reuse Disinfection Applications (NSF, 2002). The biodosimetry test program utilized one-fourth scale pilot modules, having 10-lamps, leading to conservative results due to realization of a less intense UV radiation field and reduced hydraulic mixing than is typically found with full-scale 40-lamp modules. Dose-flow relationships were obtained for both granular media-filtered and membrane-filtered wastewater reuse effluents. Although the influent velocity profiles were clearly non-homogeneous during testing, the performance of the most upstream module was not compromised and dose additivity with the number of downstream modules was clearly demonstrated.Based on the results of this verification testing, the Aquaray® 40 HO system can be sized for wastewater reuse applications using a ratio of target dose to dose delivered per module. Following review of the validation test report, the State of California Department of Health Services granted conditional acceptance for use of the Aquaray® 40 HO process in reclaimed wastewater disinfection applications.