Introducing and removing ion-exchange and other particulates rom an assembled electrodeionization stack

Apparatus comprising an electrodeionization stack, which stack comprises first and second sets of parallel chambers, the chambers of said first set alternating with chambers of said second set and separated therefrom by ion exchange membranes, the chambers of each said set comprising at least one flow path defined by an intermembrane spacer, each said at least one flow path in each set of chambers having at least one fluid channel communicating with a first fluid transfer manifold within said stack, each said at least one second channel spaced from said at least one first channel, said at least one second channel communicating with a second fluid transfer manifold within said stack, each of said at least one flow path in each set of chambers further having at least one-third channel communicating with a third fluid transfer manifold within said stack, said at least one-third channel positioned between said at least one first channel and said at least one second channel, said first, second and third manifolds adapted to transfer fluid solely into or out of said at least one flow path solely in one set of chambers, said at least one flow path in said one set of chambers adapted to be substantially filled with particulates comprising ion exchange particles if a suspension of particulates is flowed into said at least one flow path through at least one of said first and third manifolds, said at least one of first and second channels characterized by retaining at least some particulates if a suspension of particulates is flowed into said at least one flow path through at least one of said first and third manifolds.