BIOASSAY AND DOSE MONITORING PERFORMANCE OF ADRINKING WATER UV DISINFECTION SYSTEM FOR THENORTH TAHOE PUBLIC UTILITY DISTRICT

摘要

Trojan UVSwift? 4L12 ultraviolet light disinfection reactors were validated as part of arnfull-scale water treatment plant installation (North Tahoe Public Utility District; TahoernVista, CA). The validation procedure was focused on verifying the accuracy of thernTrojan UVDosimeter? rather than on minimum intensity sensor readings (I.e., SensorrnSetpoint Method). Thirty-seven measurements were taken; twenty measurements wererntaken with a lamp age of 2200 hours, and seventeen measurements were taken at arnlamp age of 5000 hours. Various ballast settings were utilized, ranging from 30 percentrnto 100 percent. Two different water transmittance values were also utilized, 90 percentrnand 95 percent. The variations in lamp age, water transmittance, and ballast outputrnwere intended to allow for a wide variety of conditions whereby the UVDosimeter?rnwould be challenged for bioassay comparative analysis. The Trojan UVDosimeter?rnappears to accurately report the UV dose when applied to the UVSwift? 4L12 reactors,rnwith no bias due to lamp aging or water transmittance.