Patent ID: 8241502

Claim:
A membrane filter device, wherein the membrane filter device includes a membrane module unit is adapted to be disposed in a water tank, the membrane module unit having a plurality of hollow fiber membrane modules, wherein said hollow fiber membrane modules having a plurality of sheet-form hollow fiber membranes, an anchoring member in which at least an end of a side of a hollow fiber membrane opening of the plurality of sheet-form hollow fiber membrane is fastened by the anchoring member so that the plurality of sheet-form hollow fiber membranes are substantially parallel to each other while leaving the end open, an end face of the anchoring member on a side where the hollow fiber membranes are exposed is substantially rectangular, and an end face of the anchoring member on a side where the hollow fiber membranes open is substantially circular, and the anchoring member has a rectangular parallelepiped section having a substantially rectangular parallelepiped shape on a side where the hollow fiber membranes are exposed, and a cylindrical section of substantially cylindrical shape on a side where the hollow fiber membranes open, and the hollow fiber membrane module satisfies the relationship 1.0 ≦W/D≦ 2.0 formula (1) wherein W(mm) is a length of the longer side of the end face where the hollow fiber membrane is exposed to the rectangular parallelepiped section and D(mm) is a diameter of the cylindrical section, and the membrane filter device satisfies the following three relationships 1000 ≦S/A≦ 2000 formula (3) 500 ≦S/V≦ 800 formula (4) 0.70 ≦V′/V≦ 0.99 formula (5), wherein S(m 2 ) is a membrane surface of the membrane module unit, V′(m 3 ) is a volume of the membrane module unit and V(m 3 ) is a volume of the water tank within wherein said membrane modules unit is to be disposed.