AWWA REUSE52109

In California, any ultraviolet (UV) disinfection system used as a part of wastewater reclamation treatment process must be capable of producing a UV dose with the same germicidal effectiveness as a UV dose of 140 milliwatt seconds per square centimeter (mWs/cm2 ) obtained by the low-pressure, UV light with a wavelength of 254 nanometers (nm). The equivalent UV dose must be delivered at a wastewater transmittance of 55 percent, measured at the wavelength of 254 nm. In addition to the low-pressure low-intensity systems which are approved for wastewater reclamation in California, other technologies such as low-pressure high-intensity, medium-pressure high-intensity, and pulsed UV systems are being proposed for use in wastewater reclamation. There are significant differences among these technologies. The low-pressure systems are monochromatic, and the majority of emissions are produced at a germicidal wavelength of 254 nm. For medium-pressure systems, the lamps are polychromatic. Since the germicidal effectiveness of the UV wavelength varies in the range of 200 to 300 nm, the estimation of the germicidal efficiency of the medium-pressure UV lamp output requires factoring in the germicidal effectiveness of each wavelength. For pulsed UV systems, the dose estimation must also take into consideration the impact of pulse frequency on disinfection. In addition, there are differences in lamp arc length, power input, reactor configuration, and dose calculation methods used by UV system manufacturers. Establishing the differences among the technologies and manufactured systems required developing a test protocol that compared these technologies against a standard method. A proposed protocol has been developed. The results from laboratory and field tests of a medium-pressure, high-intensity pilot unit are used to assess the protocol. The results reported herein represent the first field test of the proposed protocol. Includes 5 references, tables, figures.