Continuous Separation of Radionuclides from Contaminated Water by Shock Electrodialysis

Abstract

The increasing popularity of nuclear energy necessitates development of new methods to treat water that becomes contaminated with radioactive substances. Because this polluted water comprises several dissolved species (not all of which are radioactive), selective accumulation of the radionuclides is desirable to minimize the volume of nuclear waste and to facilitate its containment or disposal. In this article, we use shock electrodialysis to selectively, continuously, and efficiently remove cobalt and cesium from a feed of dissolved lithium, cobalt, cesium, and boric acid. This formulation models the contaminated water commonly found in light-water reactors and in other nuclear processes. In a three-pass process, a consistent trade-off is observed between the recovery of decontaminated water and the percentage of cobalt removed, which offers flexibility in operating the system. For example, 99.5% of cobalt can be removed with a water recovery of 43%, but up to 66% of the water can be recovered if deionization of cobalt is allowed to drop to 98.3%. In general, the energy consumed during this process (ranging between 1.76 and 4.8 kW h m(-3)) is low because only charged species are targeted and virtually no energy is expended removing boric acid, the most abundant species in solution.