A coupler for a spiral membrane filtration element having a spiral membrane enclosed within a rigid outerwrap includes a center support, a plurality of spokes extending outwardly from the center support, a circular rim coupled with the spokes, with the face of the rim being perpendicular to the axis of the overwrap. The rim includes a channel on its face for receiving a compressible seal, and a plurality of receptacles around its outer surface for joining two face-to-face adjacent couplers when a pair of aligned keepers is placed in each receptacle. Exemplary embodiments of the coupler and filtration elements and filtration assemblies are provided, as well as an associated method.