AWWA WQTC58960

Recently the use of low levels of medium- and low-pressure ultraviolet (UV) light forsuccessful inactivation of Cryptosporidium parvum oocysts has generated tremendousexcitement in the water industry. While these findings have been corroborated bynumerous independent studies at the bench-scale level, there is little experience in the U.S.with full scale disinfection of finished water, using UV light. Concerns exist with respectto the reliability of UV technology and, in addition to biodosimetry experiments tovalidate reactor performance for organism inactivation, additional issues includedetermination of the performance efficiency of the reactors, effects of suspended metalsor other water characteristics on lamp sleeve fouling, effectiveness and reliability of lampcleaning mechanisms, UV measurement sensors' stability, costs associated withretrofitting UV systems into existing water treatment plants, operation and maintenancecosts associated with employment of UV disinfection, impact of lamp aging on deliveryof target UV doses and impact of UV on disinfection byproduct (DBPs) formation ordegeneration.Although it is anticipated that experience with UV disinfection will provide informationon some of these issues, certain parameters need to be investigated before water utilitiescan commit to using UV disinfection as one of the multiple barriers for protection ofpublic health from waterborne disease causing organisms. To address some of theseoperational issues, American Water, the largest investor owned water utility in the U.S.,has been actively involved in ascertaining the long-term feasibility of applying UV fortreatment of finished water. A 12 inch diameter 4 x 1 KW, closed chamber UV reactorwas installed after granular activated carbon filtration at the Pennsylvania AmericanWater treatment plant at Hayes Mine and was operated continuously with a finishedwater flow rate of 600 gpm. Over a 12 month period, various chemical (THM, HAA,UV254, DOC, TOC, metals, nitrate, nitrites) and physical measurements (lamp voltage,current, sensor measurements) were monitored. Also, parameters such as powerconsumption and other operational issues associated with reactor function (i.e. frequencyof power outages, failing components, etc.) were recorded. Reactor validation studies wereperformed using Bacillus subtilis spores, MS2 bacteriophage and Deinococcusradiodurans as a biodosimetery surrogates and utilized various lamp configurations aswell as lamp age. Includes 7 references, figures.

Product Details

Edition:

Vol. - No.

Published:

11/02/2003

Number of Pages:

10

File Size:

1 file , 290 KB