Full Description

Ultraviolet (UV) validation of dose delivery and monitoring is required by at least four UV guidance andstandards. Validation involves measuring dose delivery using a challenge microbe under varyingconditions of flow, water UV transmittance, and lamp output. Validation is currently conductedeither on-site or at a test center. Until recently, validation was limited to 18 mgd and concernexisted that validation at a larger-scale was limited by the availability of large titers of challengemicrobe. A large-scale validation facility was constructed during 2003 in Portland, Oregon. Thefacility can pass 40 mgd of groundwater (98 % UV transmittance at 254 nm) through a UVreactor. MS2 phage and lignin sulphonate was selected as a challenge microbe and UV absorber,respectively. MS2 phage prepared in volumes greater 10 liters with concentrations greater than1011 PFU/mL was sufficient to test UV reactors at flows up to 40 mgd. MS2 injection rates,however, were adjusted to minimize excess usage of phage. Challenges associated withconducting validation included selection of target RED, validating UV sensor measurements,developing a test protocol that allowed interpolation of results, selecting appropriate inletconditions to the reactor. Includes 12 references, tables, figures.

Product Details

Edition: Vol. - No. Published: 11/02/2003 Number of Pages: 17File Size: 1 file , 670 KB