MEMBRANE FILTER UNIT

摘要

There is provided a membrane filter unit capable of ensuring durability of a hollow fiber membrane module by preventing hair, fiber, a paper piece and the like included in wastewater from bundling porous hollow fiber membranes of a hollow fiber membrane module or from entwining or getting stuck between the hollow fiber membrane and a surrounding frame member and the like, in activated sludge treatment. A membrane filter unit (5) comprises a hollow fiber membrane module (9) composed of a plurality of sheet-like hollow fiber membrane elements (10) arrayed in parallel at predetermined intervals, each of the hollow fiber membrane elements (10) obtained by arranging a great number of porous hollow fiber membranes (10a) in parallel, and an air diffuser (15) arranged below the hollow fiber membrane module (9) for releasing minute bubbles toward a lower end of the hollow fiber membrane module and generating a gas-liquid mixed flow vertically swirling between an inner space and an outer space of the hollow fiber membrane module. The membrane filter unit (5) has a residue eliminating mechanism for forming a forced flow in part of the mixed flow between the porous hollow fiber membranes and between the sheet-like hollow fiber membrane elements of the fiber membrane module (9), thereby eliminating the residues mixed in the gas-liquid mixed flow from the hollow fiber membrane module to outside.