| 摘要 |
A spiral-type separation membrane element is provided that can reduce the pressure loss caused by the transmitted water flow within a water-collecting tube without changing the outer diameter and the inner diameter of the water-collecting tube. In a spiral-type separation membrane element in which a separation membrane, a feed-side flow passageway member, and a permeate-side flow passageway member are wound in a spiral form around a porous water-collecting tube in a laminated state, the characteristic feature lies in that the feed-side flow passageway member (2) includes a net-constituting thread (2a) in a direction tilted relative to a feed solution flow direction; the net-constituting thread (2a) has a cross-sectional part such that a thread diameter (X) in a direction parallel to a feed solution flow plane is larger than a thread diameter (Y) in a direction perpendicular to the feed solution flow plane; and a central part (P1) between intersection parts of the net-constituting thread (2a) is made to have a thread diameter (Y) smaller than that of an intersection part (P2).
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