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

A spiral reverse osmosis membrane element, wherein

• a plurality of bag-shaped reverse osmosis membranes, permeated liquid passage members arranged inside said reverse osmosis membranes, and a plurality of feed liquid passage members interposed between said reverse osmosis membranes are wound around an outer surface of a hollow pipe in a manner that only the interiors of said reverse osmosis membranes communicate with through-holes formed in the surface of said hollow pipe;
• each of said feed liquid passage members is a mesh member having series of diamond-shaped meshes formed by a plurality of linear members crossing each other;
• two opposite cross-points out of four cross-points of each of said diamond-shaped meshes are in line in parallel with an axial direction of said hollow pipe;
• relationships 2 mm≦X≦5 mm and X<Y≦1.8X are both satisfied where X denotes a distance between said cross-points in a direction perpendicular to the axial direction of said hollow pipe and Y denotes a distance between said cross-points in the axial direction of said hollow pipe;
• and
• wherein the absolute value of an angle between a line connecting the cross-points which are in line in the axial direction of said hollow pipe and a mesh leg is within a range of from 29 to less than 45°.