Reduction of indoor air radon contents in German waterworks by removal of radon from water by aeration

The council directive 96/29 EURATOM laying down the Basic Safety Standards for the protection ofthe health of workers and the general public against ionising radiation might force some Europeanwater supply companies to take technical measures for lowering the indoor air radon contents in theirwaterworks. A suitable method for this, is the installation of water aeration equipment to remove radondirectly from raw water and lead it out off the building. Because water aeration equipment isfrequently used for carbon dioxide removal, experiments with a counter-current packed tower column(at half normal scale) were carried out to compare the removal behaviour of radon and carbon dioxide.Up to 80 to 85 % of both gases could be removed at air/water ratios up to 40.Additionally, investigations were carried out in a German waterworks, where flat-bed cross-flowaeration equipment is installed to remove radon and carbon dioxide from raw water. At an air/waterratio of 16 the equipment removes more than 98 % of the radon from the water (raw water radoncontent: 130 Bq/l). Since the processed air is led out of the building by a pipe, the radon degassingpotential during further treatment steps is significantly reduced, leading to average indoor air radoncontents of 0,3 kBq/m in the building.