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ULTRAVIOLET DISINFECTION STUDIES WITH CCL LISTED MICROORGANISMS
Citation:
Hayes*, S AND K. White. ULTRAVIOLET DISINFECTION STUDIES WITH CCL LISTED MICROORGANISMS. Presented at WSWRD Peer Review, Cincinnati, OH, September 27 - 29, 2004.
Impact/Purpose:
To inform the public.
Description:
Resistance to ultraviolet (UV) disinfection is an essential aspect regarding all microbial groups listed on the CCL. The U.S. drinking water industry is interested in including UV light treatment as an amendment to conventional treatment for disinfecting water supplies. UV disinfection has the potential for reducing the use of chlorine and its associated byproducts. Three CCL listed microorganisms have been tested with UV disinfection to date: A. hydrophila, H. pylori and Microsporidia. Testing was performed with a collimated beam apparatus utilizing a low pressure UV (LP-UV) light source. Greater than 5-log reduction was seen with three different species of Aeromonas at fluences of approximately 6 mJ/cm2. A 3-log reduction was achieved at fluences of less than 19 mJ/cm2 for three species of Microsporidia tested, with E. hellem being the most resistant to UV inactivation. Lowered temperatures do not appear to affect log reductions for Microsporidium. H. pylori is also easily disinfected by LP-UV irradiation, with the most resistant strain (ATCC43504) exhibiting log reductions of 4 to 5 at approximately 8 mJ/cm2. To put the above into perspective, most UV disinfection processes for drinking water deliver a minimum dose of 40 mJ/cm2.