Presentation on theme: "UV Drinking Water Treatment Emerging Technologies."— Presentation transcript:
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/cm 2 With Sensor Technology – Unknown Water Supply Class B 16 mJ/cm 2 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
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 OrganismsMain FindingsRef 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 / spores MS2 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
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