MULTI-STAGE IMMERSION-TYPE MEMBRANE SEPARATION DEVICE AND MEMBRANE SEPARATION METHOD

摘要

The present invention provides a submerged type membrane separation device and a membrane separation method which allow long-term stable filtration. In the submerged type membrane separation device including a membrane module having membrane units stacked on top of each other in stages, in each of which flat sheet membrane elements each having a separation membrane are arranged, the membrane module is constructed of various membrane units differing in sludge-filtration resistance or pure-water permeation resistance, whereby it becomes possible to extend a device operation period of time lapsing before transmembrane plugging occurs, or equivalently, the necessity to clean membranes arises. Further, it also becomes possible to design to synchronize timings with which a plurality of membrane units require cleaning.

主权项

1. A multi-stage submerged type membrane separation device comprising:
a membrane module having a plurality of membrane units stacked vertically in stages, in each of which a plurality of flat sheet membrane elements each having a sheet-shaped separation membrane are arranged; a water-to-be-treated storage tank in which water to be treated is stored and the membrane module is placed in a state of being submerged in the water to be treated; and an air diffuser installed beneath the membrane module, wherein the membrane unit placed at the lowermost stage is lower in sludge-filtration resistance or pure-water permeation resistance than any of the membrane units placed at stages higher than the membrane unit placed at the lowermost stage.