SEPARATION MEMBRANE ELEMENT

To provide a separation membrane element that restrains concentration polarization while reducing flow resistance of a supply-side flow passage and further increases a filling membrane area per element.SOLUTION: A separation membrane element includes a catchment pipe, a separation membrane, a supply-side flow passage material 2 and a permeation-side flow passage material. The supply-side flow passage material is positioned between two surfaces of the separation membrane to form a supply-side flow passage. The supply-side flow passage material is in the form of net in which fibrous row X made of a plurality of fibrous materials A21 arranged in one direction and a fibrous row Y made of a plurality of fibrous materials B22 arranged in a direction different from the fibrous row X intersect with each other three-dimensionally to form intersections. At least one of the fibrous material A and the fibrous material B is made of a yarn with a smaller diameter than at least one large diameter part in a central part R2 between an intersection part P1 of the fibrous row X and the fibrous row Y in a vertical cross section parallel to an arbitrary fibrous row, with a supply-side flow passage area ratio being in a range of 50-65%.SELECTED DRAWING: Figure 3 【課題】供給側流路の流動抵抗を低減しながら、濃度分極を抑制し、さらに１エレメントあたりの充填膜面積を増加させる分離膜エレメントの提供。【解決手段】集水管と、分離膜と、供給側流路材２と、透過側流路材とを備える分離膜エレメントであって、前記供給側流路材は、前記分離膜の二つの面の間に配置されて供給側流路を形成し、前記供給側流路材は一方向に並んだ複数の繊維状物Ａ２１から構成される繊維状列Ｘおよび前記繊維状列Ｘとは異なる方向に並んだ複数の繊維状物Ｂ２２から構成される繊維状列Ｙとが互いに立体交差して交点を形成したネット形状であり、前記繊維状物Ａおよび前記繊維状物Ｂの少なくとも一方は、任意の繊維状列に平行な縦断面において、繊維状列Ｘおよび繊維状列Ｙの交点部Ｐ１間における中央部Ｒ２が少なくとも一方の太径部に比べて細径の糸で構成され、供給側流路面積率が５０〜６５％の範囲である。【選択図】図３