Removal of radionuclides by membrane permeation combined with complexation

Membrane permeation combined with complexation was tested for radioactive wastes processing purpose. The ceramic membranes MEMBRALOX® and CéRAM INSIDE® were used. To enhance the UF separation effect, different soluble polymers and ferrocyanides, binding cobalt and caesium ions were used. The complexing agents were tested in laboratory to establish the best conditions of the process. The experiments showed a significant increase of decontamination factors while the macromolecular compounds were added. The effectiveness of complexation by each ligand is strongly dependent on pH and alkali metals concentration.

The integration of complexation with UF is one of the possibilities for liquid radioactive waste processing. The method involving different complexing agents and adsorbers creates a chance for the treatment of wide range of waste streams. The UF/complexation combination may be an alternative for reverse osmosis. The advan-tage over RO is easier operation of the process (lower pressures) and possibility of application of ceramic membranes which have good chemical and radiation stability. Since ceramic membranes can work in elevated temperatures, they can be washed by warm cleaning solutions and sterilised by steam. One of the drawbacks of seeded UF is strong dependence of complexation on pH and concentration of alkaline metals, which can be sometimes inconvenient and can result in the need of subsequent removal of specific ions by different ligands. Acknowledgments The KBN Programme 3 T09C 026 18 financially supported a part of the work concerning ceramic membrane application.