AWWA REUSE52109

AWWA REUSE52109 Comparison of UV Disinfection Technologies for Meeting California Wastewater Reclamation Criteria
Conference Proceeding by American Water Works Association, 01/01/2000

Soroushian, Fred;Norman, Julia;Patel, Mehul;Leslie, Greg;Tchobanoglous, George

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In California, any ultraviolet (UV) disinfection system used as a part ofwastewater reclamation treatment process must be capable of producing a UV dosewith the same germicidal effectiveness as a UV dose of 140 milliwatt seconds persquare centimeter (mWs/cm2 ) obtained by the low-pressure, UV light with awavelength of 254 nanometers (nm). The equivalent UV dose must be delivered at awastewater transmittance of 55 percent, measured at the wavelength of 254 nm. Inaddition to the low-pressure low-intensity systems which are approved forwastewater reclamation in California, other technologies such as low-pressurehigh-intensity, medium-pressure high-intensity, and pulsed UV systems are beingproposed for use in wastewater reclamation. There are significant differencesamong these technologies. The low-pressure systems are monochromatic, and themajority of emissions are produced at a germicidal wavelength of 254 nm. Formedium-pressure systems, the lamps are polychromatic. Since the germicidaleffectiveness of the UV wavelength varies in the range of 200 to 300 nm, theestimation of the germicidal efficiency of the medium-pressure UV lamp outputrequires factoring in the germicidal effectiveness of each wavelength. For pulsedUV systems, the dose estimation must also take into consideration the impact ofpulse frequency on disinfection. In addition, there are differences in lamp arclength, power input, reactor configuration, and dose calculation methods used byUV system manufacturers. Establishing the differences among the technologies andmanufactured systems required developing a test protocol thatcompared these technologies against a standard method. A proposed protocol hasbeen developed. The results from laboratory and field tests of a medium-pressure,high-intensity pilot unit are used to assess the protocol. The results reportedherein represent the first field test of the proposed protocol. Includes 5 references, tables, figures.