Some embodiments of the invention relate to an electrodeionization device that includes comprising a generally cylindrical housing. The cylindrical housing includes a cylindrical inner core and an inner electrode that extends around the inner core. The cylindrical housing includes a leaf arranged as a spiral winding about the inner electrode and an outer electrode that extends about the spiral winding. Active treatment cells are defined by spaces within the spiral winding and by interleaf spaces thereof. One or more sealing bands extend between membranes of the spiral winding to define fluid flow.