Spiral reverse osmosis membrane element, reverse osmosis membrane module using it, device and method for reverse osmosis separation incorporating the module

Abstract

A spiral reverse osmosis membrane element of the present invention includes a plurality of bag-shaped reverse osmosis membranes, permeated liquid passage members arranged inside the reverse osmosis membranes, and a plurality of feed liquid passage members interposed between the reverse osmosis membranes, those membranes and passage members being wound around an outer surface of a hollow pipe in a manner that only the interiors of the reverse osmosis membranes communicate with through-holes formed in the surface of the hollow pipe. Each of the feed liquid passage members is a mesh member having series of quadrilateral meshes formed by a plurality of linear members crossing each other. Two opposite cross-points out of four cross-points of each of the quadrilateral meshes are in line in parallel with an axial direction of the hollow pipe. And relations 2 mm≦X≦5 mm and X≦Y≦1.8X are both satisfied where X denotes a distance between the cross-points in a direction perpendicular to the axial direction of the hollow pipe and Y denotes a distance between the cross-points in the axial direction of the hollow pipe.