 Particles such as whole cells or cell debris, which would clog a packed bed column, readily pass through a fluidized bed.EBA can therefore be used on crude culture broths or slurries of broken cells, thereby bypassing initial clearing steps such as centrifugation and filtration, which is mandatory when packed beds are used.In older EBA column designs, the feed flow rate is kept low enough that the solid packing remains stratified and does not fluidize completely.