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