HOLLOW-FIBER REVERSE-OSMOSIS MEMBRANE ELEMENT AND MODULE

摘要

[Problem] To provide a large-bore hollow-fiber reverse-osmosis membrane element having excellent resistance to contamination and little loss in flow pressure (i.e., a high water permeation rate). [Solution] A dual-open-ended hollow-fiber reverse-osmosis membrane element in which both ends of a hollow-fiber membrane wound body are opened, the hollow-fiber membranes being arranged to cross each other by being helically wound around a porous distribution pipe, wherein the hollow-fiber reverse-osmosis membrane element is characterized in that: a) the outer diameter of the element is 260 mm or more; b) the number of windings per element length in the range from the outermost layer of the hollow-fiber membrane wound body to at least 1/8 the thickness of the wound body is 0.33-1.75; and (c) the number of windings per element length in the range from the innermost layer of the hollow-fiber membrane wound body to at least 1/4 the thickness of the wound body is greater than 1.75.