What Means “Dose” in UV-Disinfection with Medium Pressure Lamps?

The “dose” in UV-disinfection plants for water, which are equipped with (nearly monochromatic) low pressure mercury lamps is already well defined as Reduction Equivalent Fluence (REF). For plants with medium pressure mercury lamps, which emit polychromatic UV-radiation, several definitions of “dose” are possible. We measured the spectral sensitivity of spores of Bacillus subtilis ATCC 6633 and compared results gained by calculations using these spectral functions with results from irradiation with a medium pressure lamp. The measurements and calculations showed good agreement.