US 2025/0025836 A1Published application

Solution treatment method and solution treatment unit

AssigneeToray Industries, Inc.

InventorsShinichiro Yoshidomi, Izumi Nagano, Ryoma Miyamoto, Yoshiki Okamoto, Harutoki Shimura, Shigehisa Hanada

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Abstract

A solution treatment method in which a solution containing a separation target substance such as a neutral molecule is treated with a combination of a plurality of types of membranes, and a component and water desired to be left as a purified liquid are recovered while the unnecessary separation target substance is separated. More specifically, it could be helpful to provide a solution treatment method which is to be applied to a solution containing at least an electrolyte in an amount of 1000 mg/L or more and containing a low-molecular-weight nonelectrolyte molecule having a molecular weight of 70 or less, and by which the electrolyte and water are recovered while the low-molecular-weight nonelectrolyte molecule is removed, with combination of a plurality of membranes.

Claims10

Dependent claims

A solution treatment method comprising treating a raw liquid with a first separation membrane and a second separation membrane which each separate a feed liquid into a permeate liquid and a concentrated liquid, and separating the raw liquid into a purified liquid containing water and an electrolyte and a discharge liquid containing a low-molecular-weight nonelectrolyte molecule, wherein

the raw liquid is a solution containing at least an electrolyte in an amount of 1000 mg/L or more and containing a low-molecular-weight nonelectrolyte molecule having a molecular weight of 70 or less,
a permeate liquid from the first separation membrane is fed to the second separation membrane and subjected to separation treatment,
the first separation membrane exhibits, when a solution 1 with pH 7 in which 10000 mg/L of sodium chloride (NaCl) and 250 mg/L of urea are mixed is fed thereto at 36° C. and a pressure of 1.2 Mpa, an NaCl removal rate of 90% or more, the NaCl removal rate being defined by a reduction rate of a component concentration in a permeated solution relative to a component concentration in a feed liquid,
the second separation membrane exhibits when a solution 2 with pH 7 in which 1000 mg/L of sodium chloride (NaCl) and 700 mg/L of urea are mixed is fed thereto at 36° C. and a pressure of 1.8 Mpa, a urea removal rate of 85% or more, the urea removal rate being defined by a reduction rate of a component concentration in a permeated solution relative to a component concentration in a feed liquid,
a difference between a urea removal rate of the second separation membrane under the evaluation conditions of the second separation membrane specified above and a urea removal rate of the first separation membrane under the evaluation conditions of the first separation membrane specified above is 40% point or more, and
the solution treatment method satisfies any one of the following requirements (i) and (ii):
(i) a part of a permeate liquid from the second separation membrane is mixed with the raw liquid and then fed to the first separation membrane, and a whole or a part of the remainder of the permeate liquid from the second separation membrane is mixed with a concentrated liquid from the first separation membrane to afford the purified liquid;
and
(ii) a whole of a permeate liquid from the second separation membrane is mixed with the raw liquid and then fed to the first separation membrane to afford a concentrated liquid from the first separation membrane as the purified liquid.

6 more elements

A solution treatment unit comprising a first separation membrane and a second separation membrane each of which separates a feed liquid into a permeate liquid and a concentrated liquid, and being configured to separate a raw liquid into a purified liquid containing water and an electrolyte and a discharge liquid containing a low-molecular-weight nonelectrolyte molecule, wherein

the raw liquid is a solution containing at least an electrolyte in an amount of 1000 mg/L or more and containing a low-molecular-weight nonelectrolyte molecule having a molecular weight of 70 or less,
a permeate liquid line from the first separation membrane is connected to a feed liquid line to the second separation membrane,
the first separation membrane exhibits, when a solution 1 with pH 7 in which 10000 mg/L of sodium chloride (NaCl) and 250 mg/L of urea are mixed is fed thereto at 36° C. and a pressure of 1.2 Mpa, an NaCl removal rate of 90% or more, the NaCl removal rate being defined by a reduction rate of a component concentration in a permeated solution relative to a component concentration in a feed liquid,
the second separation membrane exhibits, when a solution 2 with pH 7 in which 1000 mg/L of sodium chloride (NaCl) and 700 mg/L of urea are mixed is fed thereto at 36° C. and a pressure of 1.8 Mpa, a urea removal rate of 85% or more, the urea removal rate being defined by a reduction rate of a component concentration in a permeated solution relative to a component concentration in a feed liquid,
a difference between a urea removal rate of the second separation membrane under the evaluation conditions of the second separation membrane specified above and a urea removal rate of the first separation membrane under the evaluation conditions of the first separation membrane specified above is 40% point or more, and
the solution treatment unit satisfies any one of the following requirements (i) and (ii):
(i) a permeate liquid line from the second separation membrane is branched into at least two lines, at least one of the branched lines is connected to a line of the raw liquid, a line of a mixed liquid of the raw liquid and a permeate liquid from the second separation membrane is connected to a feed line to the first separation membrane, and at least one of the remaining branched lines is connected to a concentrated liquid line from the first separation membrane to form a purified liquid line;
and
(ii) a permeate liquid line from the second separation membrane is connected to a line of the raw liquid, a line of a mixed liquid of the raw liquid and a permeate liquid from the second separation membrane is connected to a feed line to the first separation membrane, and a concentrated liquid line from the first separation membrane serves as a purified liquid line.

6 more elements

Dependencies are inferred from the claim text.