Hollow fiber membrane module and method for operating same

A hollow-fiber membrane module comprising:

• a cylindrical case having a first end and a second end in a height direction,
• a plurality of hollow-fiber membranes housed in the cylindrical case, and
• a first potting part which bonds end parts of the plurality of hollow-fiber membranes located at the first end of the cylindrical case, while the end parts of the plurality of hollow-fiber membranes are open, wherein
• the hollow-fiber membrane is a porous hollow-fiber membrane and has a breaking strength of 23 MPa or more,
• a membrane area per unit volume of the hollow-fiber membrane module is from 800 to 3,700 m2/m3,
• in a cross-section which perpendicularly intersects the height direction of the cylindrical case, a filling ratio of the hollow-fiber membranes is from 25% to 38%,
• the hollow-fiber membrane contains a solid matter containing a fluororesin-based polymer,
• at least a part of the solid matter constitutes a columnar texture,
• the columnar texture is oriented in a longitudinal direction of the hollow-fiber membrane,
• the columnar texture has a short-side length of from 0.5 μm to 3 μm, and
• an aspect ratio of the columnar texture is 3 or more.