A three-column carousel process based on a pelletized form of CST powder was designed to remove radioactive Cs-137(+) from SRS nuclear wastes. A multicomponent ion-exchange equilibrium model was used to generate cesium loading data, which were fit to the Langmuir equation to obtain effective single-component cesium isotherm parameters for representative wastes. Mass-transfer parameters were estimated by analyzing breakthrough curves for two simulated wastes. Simulations based on a pore-diffusion rate model were performed to determine the lengths of the mass-transfer zone for different feed compositions and linear velocities. The length of a single segment in the carousel process was the constant-pattern mass-transfer zone to ensure consistent high column utilization during startup and cyclic steady state. Analysis of the dimensionless groups in the mass balance equations revealed that the mass-transfer zone length is proportional to the particle Peclet number. The proportionality constant is a function of the waste composition and the Cs+ concentration in the waste. A higher distribution coefficient and isotherm nonlinearity result in a smaller proportionality constant. With this analysis designs can be easily adjusted for variations in isotherms, feed concentration, particle size, linear velocity, and intraparticle diffusivity.