Abstract: Biomass (e.g., plant biomass, animal biomass, and municipal waste biomass) is processed to produce useful intermediates and products, such as energy, fuels, foods or materials. For example, equipment, systems and methods are described that can be used to treat feedstock materials, such as cellulosic and/or lignocellulosic materials. Process streams can be upgraded, e.g., by removing undesired components utilizing simulated moving bed systems such as simulated moving bed chromatography, improved simulated moving bed chromatography, sequential simulated moving bed chromatography and/or related systems.