Minimal liquid discharge desalination systems using integrated membrane processes

A saline water treatment system comprising:

• an inlet for receiving a feed solution, a first pressure pump for delivering the feed solution to a separation module, a forward osmosis, FO, module, a second pressure pump, and a reverse osmosis, RO, module;
• the separation module comprising an inlet for receiving the feed solution from the first pressure pump, a membrane defining a permeate portion and a reject portion of the module, a first outlet in the permeate portion and a second outlet in the reject portion;
• the FO module comprising a first and second portion separated by a semipermeable membrane, wherein each portion of the FO module comprises an inlet and an outlet;
• wherein the system is configured to separate the feed solution in the separation module into a permeate solution with a reduced ion concentration and a reject solution with an increased ion concentration, the reject solution leaving the separation module at a higher hydraulic pressure than the permeate solution due to the assistance of hydraulic pressure applied at the first pressure pump;
• wherein the system is further configured to deliver a first solution to the first portion of the FO module and to deliver the reject solution from the separation module to the second portion of the FO module, to facilitate the transport of water molecules across the semipermeable membrane from the second portion to the first portion;
• wherein the system is configured to output a FO permeate solution from the first portion of the FO module and a concentrated FO reject solution from the second portion of the FO module;
• and
• wherein the system is further configured to deliver the FO permeate solution via a second pressure pump to the RO module, the RO module comprising an inlet for receiving the FO permeate solution, a RO membrane defining a RO reject portion and a RO permeate portion of the RO module, a first outlet in the RO reject portion and a second outlet in the RO permeate portion.