UV Disinfection Validation Facility

City of Portland, 
Oregon

UV Disinfection Validation Facility

Project Highlights: 
  • Validation of over 40 commercial UV reactor product lines from Calgon, Trojan, WEDECO and Aquionics at flows up to 70 mgd in accordance with the USEPA’s LT2ESWTR.
  • Development of optimized validation techniques using MS2 and T1 phage that accounts for the UV reactor’s dose distribution.
A 40-mgd UV reactor
Validation of a 40-mgd UV reactor moves large-scale UV from research to practice.

To receive inactivation credit with UV disinfection, the USEPA requires that UV systems undergo validation testing. Before 2003, UV systems installed in the U.S. were validated either on site or at a facility in Europe. Recognizing a need for a U.S. facility, Carollo developed the Portland UV Disinfection Validation Facility in Portland, Oregon.

The facility is located near the groundwater pumping station of Portland’s South Shore Well Field. The wellfield can provide on demand up to 90 mgd of chlorine-free, low UV-absorbance groundwater.

Carollo obtained funding for facility development from four UV system suppliers: Calgon Carbon Corporation, Trojan Technologies, ITT-WEDECO, and Aquionics. The design and construction of a 30-inch test train was completed in February 2003. A second 12-inch test train was added to the facility in December 2005. The facility was expanded in 2009 to provide validation at flows up to 70 mgd.

Carollo commissioned the site in March 2003 with the testing of a 40-mgd, medium-pressure UV system supplied by Calgon. Carollo has since tested over 40 commercial UV reactor technologies for drinking water and reuse applications at flowrates ranging from 1 to 70 mgd and UV transmittance values ranging from 50 to 98 percent. Since facility startup, over 2,000 challenge tests using MS2, QB, T1 and T7 coliphage and B. Pumilis spores have been used to demonstrate UV doses ranging from 5 to 200 mJ/cm2.

The test train provides highly accurate validation test results - flow is controlled to within 1 percent of target flow, UVT is controlled within 0.3 percent of target UVT, and influent and effluent concentrations are typically measured with a standard deviation of 0.04 log. Through analysis of the validation data, Carollo has developed efficient and simple dose-monitoring algorithms that predict UV dose within ± 1 mJ/cm2. The dose-monitoring algorithms are used by UV systems across North America and have been adopted by the USEPA UV Disinfection Guidance Manual as a standard method for the UV industry.

The success of the Portland Validation Facility makes large-scale validation a reality today. Large cities implementing UV disinfection can now confidently plan the use of large-scale reactors to comply with the Long-Term 2 Enhanced Surface Water Treatment Rule.