uV Drinking Water Treatment
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Transcript of uV Drinking Water Treatment
uV Drinking Water Treatment
Emerging Technologies
NSF/ANSI Standard 55• Evaluation of Microbiological Reduction Performance
Capability• Low Pressure uV Lamps• 254nm Wavelength• Performance Equated to Delivered Dose
• Class A 40 mJ/cm2 With Sensor Technology – Unknown Water Supply• Class B 16 mJ/cm2 Without Sensing Technology – Known Water Supply
• Test Organisms• Bacteriophage MS2 – Class A• S. cerevisiae/Bacteriophage T1 – Class B
How does UV inactivate micro-organisms?
Well Accepted Mechanism of UV Inactivation
At a wavelength of 254nm, UV will break the molecular bonds within micro-organismal DNA, producing thymine dimers and thereby destroying them or prohibiting growth and reproduction
253.7nm
UVC Absorbance of DNA
Emerging Technologies• Alternate uV Technologies Are Under Active Development
• LED• DBD• Excimer• MP CFL• Halogen
• uV Emissions May Be Monochromatic or Polychromatic at Wavelengths Other Than 254 nm
Market Trends
The Issue (Opportunity)• Standard 55 Performance Based Upon Dose…..• Dose Equated to Anticipated Log Reduction at 254 nm Wavelength• Relationship of Dose to Log Reduction Based Upon Established
Research and Scientific Findings• The Question (s)
• Does the Dose/Log Reduction Relationship Hold For Alternate Technologies Emitting as Wavelength (s) Other than 254 nm?
• Is There a Need for the Development of Alternative Measuring Tools?• Can These Alternate Technologies Be Built Into Standard 55?
Wavelength(nm)
Polychromatic
Monochromatic
Organisms Main Findings Ref
210, 220, 230, 240, 260, 270, 280, 290
Adenovirus • More DNA damage was observed at >260nm• Loss of viral infectivity was due to the UV damage
to a viral component at <240nm
S. Beck et al., Environ. Sci. & Technol., 2014
214, 230, 240, 254, 265, 280, 293
Bacillus / sporesMS2 coliphage
• MS2 was 3 times more sensitive to near 214nm compared to the 254 nm
• B. subtilis spores were most sensitive to 265nm
H. Mamane-Gravetz et al., Environ. Sci. & Technol., 2005
216, 230, 242, 255, 263, 271, 281, 290
Cryptosporidium parvum oocysts
• C. Parvum oocyst was most sensitive to 271nm• Oocyst can be appreciably inactivated at low UV
dose
K. Linden et al., Water Sci. & Technol., 2001
222, 228, 239, 260, 280, 289
Adenovirus • Other wavelength emitted by the polychromatic UV lamps are more effective than the 254nm emitted by LP UV.
K. Linden et al., Appl. Environ. Microbio., 2007
Summary of Previous Wavelength Works
Motion• The motion is that the uV Task Group be requested to evaluate the
available research associated with alternate uV technologies related to the germicidal treatment of water and report back to the Joint Committee their findings and recommendations for accommodating these technologies within the NSF/ANSI standards framework.
How Emerging Technologies Inactivate• How UV inactivates• 254nm comparison to other wavelengths• MS2 Surrogate potential
• E Coli• S Typhimurium LT2• Bacillus Subtilis Spores
How does 253.7nm compare to other wavelength?
Mamane-Gravetz et al., Environ. Sci. & Technol., 2005 Linden et al., Water Sci. & Technol., 2001
Beck et al., Environ. Sci. & Technol., 2014 Linden et al., Appl. Environ. Microbiol., 2007
How does MS2/254nm Inactivation compare to bacteria / waterborne pathogens?
Bowker et al., Water Research., 2011
Ren Zhuo Chen et al., Water Research., 2009
FIGU RE 4. Log inactivation of S6633 spores and M S2 at a UV fluence of 400 J/m 2 for different w avelengths, relative to LP 254 nm QPB apparatus.
How does MS2/254nm Inactivation compare to bacteria / waterborne pathogens?
Mamane-Gravetz et al., Envirron. Sci. Technology., 2005
Ren Zhuo Chen et al., Water Research., 2009
Testing Protocol Opportunities• Revision to NSF/ANSI Standard 55
• MS2 as surrogate
• Development of new NSF Certification• Alternative Surrogate