Integrated Ocean Alkalinity Enhancement And Seawater Desalination

A seawater reverse-osmosis desalination system comprising:

• a reverse osmosis unit configured to generate a freshwater stream by diverting salt from a feedwater stream into a high-salt brine stream, wherein the feedwater stream including seawater having a first salt concentration, and wherein the high-salt brine stream has a second salt concentration that is greater than the first salt concentration;
• an electrochemical reactor configured to generate a reduced-salt stream having a third salt concentration that is lower than the first salt concentration by converting the salt contained in the high-salt brine stream into an acid substance and a base substance such that the acid substance is primarily contained in an acid product stream and the base substance is primarily contained in a base product stream;
• a mixing device configured to generate the feedwater stream supplied to the reverse osmosis unit by combining the reduced-salt stream and a seawater stream including said seawater;
• and
• a control system configured to:
• determine a target feedwater pH level;
• determine a target reduced-salt pH level utilizing the target feedwater pH level and a seawater pH level of the seawater used to form the feedwater stream;
• and
• control one of the electrochemical reactor and the mixing device to modify a concentration of one of the acid substance and the base substance contained in the reduced-salt stream until a reduced-salt stream pH level of the reduced-salt stream is equal to the target reduced-salt pH level, whereby subsequent mixing of the reduced-salt stream and the seawater stream causes the feedwater stream to have a feedwater pH level that is equal to the target feedwater stream pH level.