To provide a cation exchange membrane which is less susceptible to swelling or elongation during electrolysis of a potassium chloride aqueous solution even without permitting water absorption or swelling immediately prior to mounting it in an electrolyzer, and a method whereby it possible to stably produce a potassium hydroxide aqueous solution without necessity to conduct an operation for water absorption or swelling immediately prior to mounting the membrane in the electrolyzer. A cation exchange membrane comprising a polymer having cation exchange groups, wherein in cations (100 mol %) contained in the cation exchange membrane, the total of potassium ions and sodium ions is at least 99 mol %, and in the total (100 mol %) of potassium ions and sodium ions contained in the cation exchange membrane, the potassium ions are 80-98 mol % and the sodium ions are 20-2 mol %.

To provide a cation exchange membrane which is less susceptible to swelling or elongation during electrolysis of a potassium chloride aqueous solution even without permitting water absorption or swelling immediately prior to mounting it in an electrolyzer, and a method whereby it possible to stably produce a potassium hydroxide aqueous solution without necessity to conduct an operation for water absorption or swelling immediately prior to mounting the membrane in the electrolyzer. A cation exchange membrane comprising a polymer having cation exchange groups, wherein in cations (100 mol %) contained in the cation exchange membrane, the total of potassium ions and sodium ions is at least 99 mol %, and in the total (100 mol %) of potassium ions and sodium ions contained in the cation exchange membrane, the potassium ions are 80-98 mol % and the sodium ions are 20-2 mol %.

Processes for regenerating alkali process streams are disclosed herein, including streams containing sodium hydroxide, magnesium hydroxide, and combinations thereof. Systems for regenerating alkali process streams are disclosed herein, including streams containing sodium hydroxide, magnesium hydroxide, and combinations thereof.

Processes for regenerating alkali process streams are disclosed herein, including streams containing sodium hydroxide, magnesium hydroxide, and combinations thereof. Systems for regenerating alkali process streams are disclosed herein, including streams containing sodium hydroxide, magnesium hydroxide, and combinations thereof.

An aqueous caustic composition comprising: a caustic component; an amino acid additive adapted to provide an extended buffering effect to the caustic composition when such is exposed to an acid; and water, wherein the caustic component and the amino acid additive are present in a molar ratio ranging from 15:1 to 5:1. Methods of using such compositions are also disclosed.

An aqueous caustic composition comprising: a caustic component; an amino acid additive adapted to provide an extended buffering effect to the caustic composition when such is exposed to an acid; and water, wherein the caustic component and the amino acid additive are present in a molar ratio ranging from 15:1 to 5:1. Methods of using such compositions are also disclosed.

An aqueous caustic composition comprising: a caustic component; an alkanolamine additive adapted to provide an extended buffering effect to the caustic composition when such is exposed to acid; and water. Uses and methods of using such compositions are also disclosed.

An aqueous caustic composition comprising: a caustic component; an additive adapted to provide an extended buffering effect to the caustic composition when such is exposed to an acid; and water. Methods of using such compositions are also disclosed.

A method includes treating a first brine stream including a plurality of minerals with an anti-scalant to produce a treated brine. The first brine stream is provided by a wastewater treatment system. The method also includes directing the treated brine to a first nanofiltration (NF) system disposed downstream from and fluidly coupled to the wastewater treatment system, generating a first NF permeate stream and a first NF non-permeate stream from the treated brine in the first NF system, directing the first NF non-permeate stream to a mineral removal system disposed downstream from and fluidly coupled to the first NF system, and removing the plurality of minerals from the first NF non-permeate stream to generate a first overflow stream in the mineral removal system. The first overflow stream comprises at least a portion of the plurality of minerals. The method also includes routing a first portion of the first overflow stream to a hydrochloric acid (HCl) and sodium hydroxide (NaOH) production system disposed downstream from and fluidly coupled to the mineral removal system. The HCl and NaOH production system includes a second NF system that may receive the first portion of the first overflow stream and may generate a second brine stream from the first portion of the first overflow stream. The method further includes directing the second brine stream to a first electrodialysis (ED) system disposed within the HCl and NaOH production system and fluidly coupled to the second NF system. The first ED system may generate HCl and NaOH from the second brine stream.

A method includes treating a first brine stream including a plurality of minerals with an anti-scalant to produce a treated brine. The first brine stream is provided by a wastewater treatment system. The method also includes directing the treated brine to a first nanofiltration (NF) system disposed downstream from and fluidly coupled to the wastewater treatment system, generating a first NF permeate stream and a first NF non-permeate stream from the treated brine in the first NF system, directing the first NF non-permeate stream to a mineral removal system disposed downstream from and fluidly coupled to the first NF system, and removing the plurality of minerals from the first NF non-permeate stream to generate a first overflow stream in the mineral removal system. The first overflow stream comprises at least a portion of the plurality of minerals. The method also includes routing a first portion of the first overflow stream to a hydrochloric acid (HCl) and sodium hydroxide (NaOH) production system disposed downstream from and fluidly coupled to the mineral removal system. The HCl and NaOH production system includes a second NF system that may receive the first portion of the first overflow stream and may generate a second brine stream from the first portion of the first overflow stream. The method further includes directing the second brine stream to a first electrodialysis (ED) system disposed within the HCl and NaOH production system and fluidly coupled to the second NF system. The first ED system may generate HCl and NaOH from the second brine stream.