USE OF UV-IRRADIATION FOR THE DISINFECTION OF WATER .1. MICROBIOLOGICAL INVESTIGATIONS IN DRINKING-WATER

  • 1 January 1988
    • journal article
    • research article
    • Vol. 185  (4-5) , 350-367
Abstract
As a physical disinfection method without chemicals required the ultraviolet irradiation was tested for disinfection of drinking water. The survival was measured as a function of exposure to radiation for Salmonella enteritidis, Enterobacter cloacae, Citrobacter freundii, Serratia marcescens, Escherichia coli, Klebsiella pneumoniae and Streptococcus faecium. The bacteria were grown in trypton soya broth until they were well into the exponential phase. Two different UV-disinfection units were tested. Both consist of cylindrical shaped chambers with one low-pressure mercury-discharge lamp with their longitudal axis parallel to the chambers. With 106 cfu/ml the experiments were done with three different rates of flow of 7,2 m3/h, 4,0 m3/h and 2,0 m3/h. The minimum exposures to radiation necessary to cause a 99.999% reduction were 10-86 mWs/cm2 depending on the testbacterium and on the UV-disinfection unit. The minimum doses ranged for S. enteritidis up to 13 mWs/cm2, for E. coli up to 21 mWs/cm2, for K. pneumoniae up to 39 mWs/cm2, for S. faecium up to 42 mWs/cm2, for E. cloacae up to 43 mWs/cm2, for C. freundii up to 72 mWs/cm2, and for S. marcescens up to 86 mWs/cm2.