A column carousel system was designed to treat nuclear waste at the Savannah River Site. A carousel model was used to simulate cesium removal in an ion-exchange carousel loaded with crystalline silicotitanate (CST) granules. The model accounts for axial dispersion and resistance to film and intraparticle diffusion. The effect of resistance to intraparticle diffusion on the required column volumes is significant. Values of the effective diffusivity of 0.25 to 0.6 X 10(-10) m(2)/s were estimated from bench-scale column experiments. This range of values resulted in a variation of column volumes by a factor of 3. The Zheng-Anthony-Miller equilibrium model was used to estimate Cs isotherms. The largest cai ousel volume did not result from waste with the lowest equilibrium loading. For wastes with low equilibrium loadings, the switching interval increased which increases the volume of CST required to treat the same volume of waste.