Ultraviolet (UV) validation of dose delivery and monitoring is required by at least four UV guidance and
standards. Validation involves measuring dose delivery using a challenge microbe under varying
conditions of flow, water UV transmittance, and lamp output. Validation is currently conducted
either on-site or at a test center. Until recently, validation was limited to 18 mgd and concern
existed that validation at a larger-scale was limited by the availability of large titers of challenge
microbe. A large-scale validation facility was constructed during 2003 in Portland, Oregon. The
facility can pass 40 mgd of groundwater (98 % UV transmittance at 254 nm) through a UV
reactor. 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 than
1011 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 with
conducting validation included selection of target RED, validating UV sensor measurements,
developing a test protocol that allowed interpolation of results, selecting appropriate inlet
conditions to the reactor.
Includes 12 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 670 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 17 |
| Published : | 11/02/2003 |
