Ultraviolet (UV) radiation effectively inactivates common pathogens found in ground and surface waters such as Cryptosporidium, Giardia, and most bacterial pathogens (e.g. E. coli). Water treatment facilities are now using UV radiation for disinfection of drinking water, supplementing standard chemical treatment. This paper will give an overview of the National Institute of Standards and Technologys (NIST) involvement in research concerning the disinfection of drinking water with UV light. A transportable tunable UV laser system for providing a known irradiance (µW/cm2) or dose (mJ/cm2) suitable for irradiating water samples in petri dishes over the wavelength range of 210 nm to 300 nm will be described. This is not the first time NIST has been involved with the UV disinfection of drinking water. Previously, NIST participated in research to calibrate and characterize UV sensors used in water disinfection facilities. A tunable laser provides advantages over the traditional use of bandpass filters with spectrally broad UV sources. The most apparent advantage of the laser is it provides light at a single wavelength that is fully tunable, allowing any wavelength to be selected, and not relying on the particular bandpass filters available. This also reduces the complexity of weighting the spectral source with the filter bandpass function. Another advantage of a laser is that it can produce higher power levels than a traditional laboratory UV source, especially below 250 nm, in theory. In practice, a tunable UV laser is more complex than traditional UV sources and requires certain design considerations to provide the desired spectral purity and spatial uniformity. The NIST tunable UV laser irradiance facility design and key components will be discussed, including modifications in the field to provide the required irradiance levels. The unique challenges encountered in deploying a tunable laser to a remote laboratory location are discussed.
Proceedings Title: IOA & IUVA 2013 World Congress & Exhibition
Conference Dates: September 22-26, 2013
Conference Location: Las Vegas, NV
Pub Type: Conferences
Action Spectra, Ultraviolet Light, Tunable Laser, Water Disinfection, Medium Pressure UV, Low Pressure UV, Water Pathogens