US 12,172,917 B2
Pure-water production device and pure-water production method
Yuki Nakamura, Tokyo (JP); Kazushige Takahashi, Tokyo (JP); and Keisuke Sasaki, Tokyo (JP)
Assigned to ORGANO CORPORATION, Tokyo (JP)
Appl. No. 17/437,975
Filed by ORGANO CORPORATION, Tokyo (JP)
PCT Filed Feb. 13, 2020, PCT No. PCT/JP2020/005550
§ 371(c)(1), (2) Date Sep. 10, 2021,
PCT Pub. No. WO2020/184044, PCT Pub. Date Sep. 17, 2020.
Claims priority of application No. 2019-045327 (JP), filed on Mar. 13, 2019.
Prior Publication US 2022/0177340 A1, Jun. 9, 2022
Int. Cl. B01D 61/02 (2006.01); B01D 61/08 (2006.01); B01D 61/48 (2006.01); B01D 61/58 (2006.01); C02F 1/44 (2023.01); C02F 1/66 (2023.01); C02F 9/00 (2023.01); C02F 1/469 (2023.01); C02F 101/10 (2006.01)
CPC C02F 9/00 (2013.01) [B01D 61/025 (2013.01); B01D 61/026 (2022.08); B01D 61/08 (2013.01); B01D 61/48 (2013.01); B01D 61/58 (2013.01); B01D 2311/18 (2013.01); B01D 2311/2523 (2022.08); B01D 2317/025 (2013.01); C02F 1/441 (2013.01); C02F 1/4695 (2013.01); C02F 1/66 (2013.01); C02F 2101/10 (2013.01); C02F 2301/046 (2013.01); C02F 2301/066 (2013.01); C02F 2301/08 (2013.01)] 7 Claims
OG exemplary drawing
 
1. A pure-water production method comprising:
(a) supplying water to be treated to a first reverse osmosis membrane device,
(b) supplying permeated water from the first reverse osmosis membrane device to a second reverse osmosis membrane device,
(c) supplying permeated water from the second reverse osmosis membrane device to an electrodeionization device,
(d) supplying concentrated water from the first reverse osmosis membrane device to a brine tank,
(e) supplying to the brine tank at least one concentrated water selected from the group consisting of concentrated water from the second reverse osmosis membrane device and concentrated water from the electrodeionization device,
(f) supplying the concentrated water in the brine tank to a third reverse osmosis membrane device, wherein a pH adjusting agent is added to the concentrated water supplied from the brine tank at a location between the brine tank and the third reverse osmosis membrane device in an amount effective to adjust a pH of the concentrated water supplied from the brine tank to a value of less than 6.0,
(g) supplying permeated water from the third reverse osmosis membrane device to the water to be treated,
(h) taking out treated water from the electrodeionization device as pure water, wherein
the second reverse osmosis membrane device is a high-pressure reverse osmosis membrane device.