Desalination method for producing freshwater by reverse osmosis of seawater

A desalination method comprising:

• providing a membrane system configured to perform a reverse osmosis of seawater, the membrane system included in a perforated casing submerged in an ocean at a depth selected to provide a hydrostatic pressure for generating the reverse osmosis, the membrane system comprising a plurality of membrane discs mounted to a freshwater collection conduit in a spaced array, each membrane disc comprising a membrane substrate coated with a membrane film in flow communication with the seawater at the depth, the freshwater collection conduit comprising a tubular having a plurality of orifices therethrough in flow communication with the membrane discs at a low-pressure side thereof, the freshwater collection conduit configured to receive freshwater produced by the reverse osmosis (RO) of the seawater by the membrane discs;
• providing a pumping system comprising a casing in flow communication with the freshwater collection conduit configured to receive the freshwater, a shaft rotatably mounted in the casing and a plurality of impellers attached to the shaft configured to pump the freshwater through the casing to a surface of the ocean, the casing configured to provide the low-pressure side for the membrane discs by pumping of the freshwater by the impellers;
• directing the seawater through the membrane discs from the high-pressure side to the low-pressure side thereof using the hydrostatic pressure to produce the freshwater and a concentrate;
• collecting the freshwater directed through the membrane discs;
• diffusing the concentrate into the ocean at the depth;
• pumping the freshwater to a surface of the ocean using the pumping system;
• and
• transporting the freshwater to land.