THE DISINFECTION OF WATER WITH UV RADIATION AND TYPE-TESTING OF UV-DISINFECTION PLANTS FOR DRINKING WATER

摘要

Disinfection of drinking water with UV-radiation has been put on a new basis in Austria: each new plant must be prototype tested following the Austrian Standard OENORM M 5873. A minimum Reduction Equivalent Dose (RED) of 400 J/m~2 of radiation with wavelength 253.7 nm is required which must be proven with a biodosimeter of defined UV-susceptibility. In addition a UV-sensor with absolute calibration for irradiance in W/m~2 is necessary which measures the reference irradiance and a minimum reference irradiance must be kept in. For type-testing the water flowing into the disinfection plant is seeded with microorganisms and UV-transmission is regulated in adding sodium-thiosulphate. In flow through systems the resulting RED can be strongly influenced by dose distributions among the microorganisms after irradiation. If the hydraulic behaviour of the plant is not optimized significant dose distributions occur which reduce the RED. At present biodosimetry is the only method to measure the efficiency of a UV-disinfection plant for drinking water.