Cesium removal from high-pH, high-salt wastewater using crystalline silicotitanate sorbent

J. F. Walker, P. A. Taylor, D. D. Lee

Research output: Contribution to journalConference articlepeer-review

19 Scopus citations

Abstract

Treatment and disposal options for Department of Energy (DOE) underground storage tank waste at Hanford, Savannah River, Idaho National Engineering and Environmental Laboratory (INEEL), and Oak Ridge National Laboratory (ORNL) are limited by high gamma radiation fields that are produced by high concentrations of cesium in the waste. Treatment methods are needed to remove the cesium from the liquid waste and thus concentrate the cesium into high-activity, remote-handled waste forms. The treated liquids could then be processed and disposed of by more cost-effective means with less radiation exposure to workers. A full-scale demonstration of one cesium removal technology has been conducted at ORNL. This demonstration utilizes a modular, mobile ion-exchange system and existing facilities for the off-gas system, secondary containment, and utilities. The ion-exchange material, crystalline silicotitanate (CST), was chosen on the basis of its effectiveness in laboratory tests. The CST, which was developed through a Cooperative Research and Development Agreement between DOE and private industry, has several advantages over current organic ion-exchange technologies. These advantages include (1) the ability to remove cesium in the presence of high concentrations of potassium, (2) a high affinity for cesium in both alkaline and acidic conditions, (3) physical stability over wide alkaline and acidic ranges, and (4) the elimination of large volumes of secondary waste required for regeneration of organic ion exchangers. Approximately 116,000 L of supernate was processed during the demonstration with ~1,142 Ci of 137Cs removed from the supernate and loaded onto 265L (70 gal) of sorbent. The supernate processed had a high salt content, about 4 M NaNO3, and a pH of 12 to 13. This paper discusses the results of the full- scale demonstration and compares these results with data from the laboratory tests.

Original languageEnglish
Pages (from-to)1167-1181
Number of pages15
JournalSeparation Science and Technology (Philadelphia)
Volume34
Issue number6-7
DOIs
StatePublished - 1999
EventProceedings of the 1997 10th Symposium on Separation Science and Technology for Energy Applications - Gatlinburg, TN, USA
Duration: Oct 20 1997Oct 24 1997

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