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Reduction of Microbial Contaminants in Drinking Water by Ultraviolet Light Technology: ETS UV MODEL UVL-200-4 (Report and Statement)
Citation:
Bartley, B. AND Jeff Adams. Reduction of Microbial Contaminants in Drinking Water by Ultraviolet Light Technology: ETS UV MODEL UVL-200-4 (Report and Statement). U.S. EPA Office of Research and Development, Washington, DC, EPA/600/R-13/250, 2014.
Impact/Purpose:
Validation study of low-pressure UV reactor system for disinfection of drinking water with application to inactivation of cryptosporidium and giardia. Study results supports State water agencies to review and permit disinfection credits for the treatment.
Description:
Final technical report provides test methods used and verification results to be published on ETV web sites. The ETS UV System Model UVL-200-4 was tested to validate the UV dose delivered by the system using biodosimetry and a set line approach. The set line for 40 mJ/cm2 Reduction Equivalent Dose (RED) was based on validation testing at three (3) set points. A set point is defined at a single flow rate and irradiance output that delivers the targeted UV dose. The results of the three set point tests were used to develop the setline that defined the maximum flow rate and minimum irradiance output required to ensure that a 40 mJ/cm2 RED is achieved. The microorganism used for the validation was MS2 coliphage virus. ETS selected flow rates for testing of 15, 20, and 25 gpm based on the unit design and preliminary screening tests. The lowest irradiance tested was 7.0 W/m2 which occurred with full power to the unit and a feed water Ultraviolet Transmission (UVT) of 79%. The measured RED was adjusted for RED bias and uncertainty to determine the validation factor for calculating log inactivation of Cryptosporidium. The validation factor and validated dose calculations were performed as specified in the USEPA Ultraviolet Design Guidance Manual (UVDGM-2006). Based on the results of these tests and the calculated validation factor, the UVL-200-4 achieved a minimum of 4.0 log reduction credit for Cryptosporidium at all of the test flow rates and corresponding irradiance levels. Some regulatory agencies have established a standard for spray parks and other applications based on a validated dose (REDVal) of 40 mJ/cm2 based on MS2, as the pathogen. The calculation of the validation factor for a validated dose based on MS2 was performed using BRED set equal to 1.0. The UVL-200-4 achieved a REDVal of 40 mJ/cm2 at all set points tested.
