Evaluation of improved techniques for the removal of fission products from process wastewater and groundwater: FY 1997 status

The primary goals of this effort in FY 1997 were to survey local end users of wastewater treatment technology and then to evaluate recently available treatment processes in light of user needs. Survey results indicate that local sites are confronted with a limited, and shrinking, budget for treating aqueous waste streams. Therefore, a process will be selected primarily on the basis of sorbent costs, use of existing equipment, and disposal costs for spent processing materials. Current laboratory testing and economic studies have been directed toward addressing the technical issues specific to the removal of {sup 90}Sr and {sup 137}Cs from groundwater and process wastewater. This year`s efforts have concentrated on evaluating the engineered form of crystalline silicotitanates (CSTs) for near neutral pH applications. Both powder and pellet forms of CST can be obtained through UOP; this task evaluated only the engineered form of the sorbent for wastewater remediation. Preliminary experimental efforts included measuring the average particle size, surface water content, total sodium content, ion exchange capacity, and equilibration mixing time. The as received material contains approximately 10% fines, which adhere to the CST pellet. The cesium and strontium ion-exchange capacities, based on multiple contacts with 50 ppm of the metal, are 0.8 meq/g and 1.1 meq/g, respectively. Batch tests indicated that an equilibrium mixing time of 100 h was required for cesium sorption. Group 2 cations (Sr, Ca, and Mg) required greater than 500 h. Particle diffusion coefficients were estimated for each of these cations from the batch studies