AWWA ACE58214

Recently the use of low levels of medium- and low-pressure ultraviolet (UV) light for successfulinactivation of Cryptosporidium parvum oocysts has generated tremendous excitement in thewater industry. While these findings have been corroborated by numerous independent studies atthe bench-scale level, there is little experience in the U.S. with full scale disinfection of finishedwater, using UV light. Concerns exist with respect to the reliability of UV technology and, inaddition to biodosimetry experiments to validate reactor performance for organism inactivation,additional issues include determination of the performance efficiency of the reactors, effects ofsuspended metals or other water characteristics on lamp sleeve fouling, effectiveness andreliability of lamp cleaning mechanisms, UV measurement sensors' stability, costs associatedwith retrofitting UV systems into existing water treatment plants, operation and maintenancecosts associated with employment of UV disinfection, impact of lamp aging on delivery of targetUV doses and impact of UV on disinfection byproduct (DBPs) formation or degeneration.Although it is anticipated that experience with UV disinfection will provide information on someof these issues, certain parameters need to be investigated before water utilities can commit tousing UV disinfection as one of the multiple barriers for protection of public health fromwaterborne disease causing organisms. To address some of these operational issues, AmericanWater, has been actively involved inascertaining the long-term feasibility of applying UV for treatment of finished water. A 12 inchdiameter 4 x 1 KW, closed chamber UV reactor was installed after granular activated carbonfiltration at the Pennsylvania American Water treatment plant at Hayes Mine and was operatedcontinuously with a finished water flow rate of 600 gpm. Over a 12 month period, variouschemical (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. frequency ofpower outages, failing components, etc.) were recorded. Reactor validation studies were performedusing Bacillus subtilis spores, MS2 bacteriophage and Deinococcus radiodurans as abiodosimetry surrogates and utilized various lamp configurations as well as lamp age. Includes 7 references, figures.

Product Details

Edition:

Vol. - No.

Published:

06/15/2003

Number of Pages:

9

File Size:

1 file , 420 KB