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Removal of Viruses in Drinking Water- Ultrafiltration Module with a Cut Fiber, Dow Chemical Company - Dow Water & Process Solutions, SFD-2880 - Ultrafiltration Module
Citation:
Blumenstein, M., B. Bartley, AND J. Q. ADAMS. Removal of Viruses in Drinking Water- Ultrafiltration Module with a Cut Fiber, Dow Chemical Company - Dow Water & Process Solutions, SFD-2880 - Ultrafiltration Module. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-12/026, 2012.
Impact/Purpose:
To inform the public.
Description:
The purpose of this verification was a cut fiber challenge study for the Dow Chemical Company SFD-2880 UF membrane module. MS2 coliphage virus was the surrogate challenge organism. The challenge tests followed the requirements of the Department of Health Victoria (Australia) Draft guidelines for validating treatment processes for pathogen reduction, supporting Class A water recycling schemes in Victoria. Five new fully integral modules were challenged with MS2. Then, one fiber in each module was cut, and the modules were all tested again with MS2. The modules were operated at a target flux of 70 gallons per square foot per day (gfd), which equates to a flow of 40.3 gallons per minute (gpm). The test data did not show any significant reduction in virus removal with a cut-fiber, so a second round of testing was conducted with higher MS2 challenge concentrations. For the retests, the cut-fiber challenges were conducted first, followed by the intact module tests after the cut fibers were pinned. The average log removal value (LRV) was calculated for each module, as well as LRVs for each feed/filtrate sample pair. From this data, the LRVC-TEST was determined as the lowest mean LRV, and also the lowest sample pair LRV. Table VS-i provides a summary of the LRVC-TEST data. Table VS-i. LRVC-TEST for Each Round of Testing Intact Modules Cut Fiber Tests Mean LRV Lowest LRV Mean LRV Lowest LRV Round 1 3.73 3.44 3.44 2.98 Round 2 2.59 2.39 2.46 2.37 To evaluate whether there was significantly lower virus removal with a cut fiber, the LRVs for each feed/filtrate sample pair were pooled together, and the paired-difference t statistic was calculated using Microsoft® Excel®. The intact module vs. cut-fiber t statistic for the first round of tests is 1.15. This value is below the critical t value of 2.15, indicating that virus removal was not significantly impacted by the cut fiber. For the second round of tests, the paired-difference t statistic is 5.00, this time demonstrating a statistically significant drop in LRV.