EVALUATION OF THE EFFICIENCY OF PLANTS FO R UV-DISINFECTION OF DRINKING-WATER

The increasing application of UV-radiation for disinfection of drinkin g water in Austria makes it necessary to prove the effectiveness of UV -disinfection plants. For this purpose the dose applied to the water m ust be measured, a form of a UV-dosimeter has to be used. Until some y ears ago various strains of microorganisms were added to the water and the inactivation caused by the disinfection plant was measured. This method, however, gives no reliable information about the UV-dose attai ned, as the applied uncalibrated microorganisms may have varying UV-su sceptibility. Therefore the results were not comparable. The applicati on of biodosimeters, for instance spores of Bacillus subtilis, the UV- susceptibility of which has been measured exactly in a laboratory irra diation device, gives the possibility to obtain quantitative informati on about the UV-dose produced by disinfection plants for drinking wate r. Commercially available UV-disinfection units were tested using a bi odosimeter, their disinfection capability and permissible working para meters were determined. The influence of a serial arrangement of two i rradiation chambers upon the overall dose was measured.