US 12,383,867 B2
Method for operating membrane filtration unit and membrane filtration unit
Kentaro Kobayashi, Otsu (JP); and Atsushi Kobayashi, Otsu (JP)
Assigned to Toray Industries, Inc., Tokyo (JP)
Appl. No. 17/432,675
Filed by Toray Industries, Inc., Tokyo (JP)
PCT Filed Feb. 26, 2020, PCT No. PCT/JP2020/007878
§ 371(c)(1), (2) Date Aug. 20, 2021,
PCT Pub. No. WO2020/175593, PCT Pub. Date Sep. 3, 2020.
Claims priority of application No. 2019-032311 (JP), filed on Feb. 26, 2019.
Prior Publication US 2022/0032234 A1, Feb. 3, 2022
Int. Cl. B01D 63/04 (2006.01); B01D 63/02 (2006.01); B01D 65/02 (2006.01); B01D 65/08 (2006.01); B01D 71/34 (2006.01); C02F 1/44 (2023.01); C02F 103/32 (2006.01)
CPC B01D 63/046 (2013.01) [B01D 63/024 (2013.01); B01D 65/02 (2013.01); B01D 65/08 (2013.01); B01D 71/34 (2013.01); C02F 1/44 (2013.01); B01D 2221/06 (2013.01); B01D 2311/14 (2013.01); B01D 2313/24 (2013.01); B01D 2315/10 (2013.01); B01D 2315/20 (2013.01); B01D 2317/04 (2013.01); B01D 2321/04 (2013.01); B01D 2321/12 (2013.01); B01D 2321/18 (2013.01); B01D 2325/38 (2013.01); C02F 2103/32 (2013.01)] 6 Claims
OG exemplary drawing
 
1. A method of operating a membrane filtration unit, the membrane filtration unit comprising a plurality of hollow fiber membrane modules connected to each other in parallel, each hollow fiber membrane module comprising a container which has a raw liquid inlet, a filtrate outlet, and a raw liquid outlet and is filled with hollow fiber membranes,
the method comprising:
a filtration step of introducing a raw liquid into the container from the raw liquid inlet, filtering the raw liquid through the hollow fiber membranes from a primary side to a secondary side, and leading out resulting filtrate to outside the container from the filtrate outlet;
a collection step of causing the filtrate existing in the container to flow in a reverse direction through the hollow fiber membranes from the secondary side to the primary side and leading out resulting backflow liquid to outside the container from at least one of the raw liquid inlet and the raw liquid outlet; and
a recovery step of introducing the backflow liquid into the container again from at least one of the raw liquid inlet and the raw liquid outlet, filtering the backflow liquid through the hollow fiber membranes from the primary side to the secondary side, and leading out resulting recovery liquid to outside the container from the filtrate outlet,
wherein a relation of n1≥n2>n3 is satisfied, where n1 is the number of the hollow fiber membrane modules simultaneously used in executing the filtration step, n2 is the number of the hollow fiber membrane modules simultaneously used in executing the collection step, and n3 is the number of the hollow fiber membrane modules simultaneously used in executing the recovery step;
wherein the filtration step introduces raw liquid through n1 hollow fiber membrane modules, the collection step introduces filtrate into n2 hollow fiber membrane modules, and the recovery step introduces backflow liquid into n3 hollow fiber membrane modules.