The EIX process for radioactive waste treatment

The use of an electric potential in place of chemical reagents to elute ion-exchange media by ion migration, as well as perform redox and pH changing reactions is of considerable importance in simplifying subsequent processing stages, such as, the recovery or disposal of the concentrate. The process has become known as Electrochemical Ion Exchange (EIX). By making multiple and complete use of ion exchange capacity in this way, large volume reduction factors can be achieved for only <5% (depending on the feed concentration) of the energy required for evaporation. AEA Technology has developed EIX over the last decade from concept to pilot demonstration, and during the last five years has gained vast experience in the design, build and operation of pilot systems (often as one stage integrated into a larger processing plant) fora variety of applications. The principal application areas for EIX relate to the removal/recovery of metals from aqueous streams [1]. These include: the decontamination of streams produced by Pressurised Water Reactors (PWRs) and the separation of radioactivity from tank waste storage facilities, the selective removal and recovery of precious metals from metal refining operations and base metals from electroplating rinse waters, the treatment of hospital waste (active) streams and the removal of silver from photographic wash waters [2]. The process has also been used successfully to remove toxic heavy metals, such as arsenic, from drinking water supplies. The technology has proven to be both robust and reliable. Direct comparison with ion exchange and evaporation has demonstrated significant cost saving for the majority of applications listed above (C) 1997 Published by Elsevier Science Ltd.