Removal of ^234,238U, ²²⁶Ra, ²¹⁰Po and ²¹⁰Pb from drinking water by ion exchange

Six organic and five inorganic ion exchangers were studied for the removal of natural radionuclides from drinking water. In the first phase, distribution coefficients (K_D) of uranium and radium were determined in three model solutions: a good quality water, an Fe-Mn-rich water and a saline water simulant. The exchangers showing highest K_D´s for U and Ra were tested in column mode experiments for the removal of U, ²²⁶Ra, ²¹⁰Po and ²¹⁰Pb from a real ground water. Considering the total 1800 processed bed volumes, the best decontamination factors (DF) for U, 20-120, were obtained with the strong base anion exchange resin. The most efficient exchangers for the removal of ²²⁶Ra were the weak and strong cation resins and zeolite A. With use of long regeneration intervals, conventional organic resins are thus most suitable for the removal of radionuclides. When only a few hundred bed volumes were processed, with the corresponding regeneration interval about one week, the aminophosphonate resin was most effective for the removal of both uranium and radium. ²¹⁰Po and ²¹⁰Pb in ground water were mainly bound in particles and adsorbed on the surface of the anion resins. The use of the aminophosphonate resin to remove uranium and radium would therefore require an anion resin to take up polonium and lead.