System and method of desalination of water

A method for water treatment comprising:

• supplying at least one water treatment unit including at least one membrane and having a feed water inlet at a feed side of said at least one membrane and a permeate outlet at a permeate side of said at least one membrane;
• feeding feed water containing foulants to said at least one water treatment unit via said feed water inlet at a feed pressure which exceeds the osmotic pressure of said feed water, thereby causing permeate to flow through said at least one membrane to said permeate side of said at least one membrane and foulants to be trapped in said at least one membrane;
• and
• intermittently cleaning said at least one membrane by causing said permeate to pass through said at least one membrane from said permeate side to said feed side, thereby dislodging foulants from said at least one membrane into said feed water at said feed side of said at least one membrane, enabling said foulants to be flushed from said feed side to a location outside of said at least one water treatment unit by:
• at least one of narrowing and closing said permeate outlet, thereby causing an increase in the pressure of said permeate at said permeate side of said at least one membrane;
• and
• reducing said feed pressure by at least 5%.

A method for water treatment comprising:

• supplying at least one water treatment unit including at least one membrane and having a feed water inlet at a feed side of said at least one membrane and a permeate outlet at a permeate side of said at least one membrane;
• feeding feed water containing foulants to said at least one water treatment unit via said feed water inlet at a feed pressure which exceeds the osmotic pressure of said feed water, thereby causing permeate to flow through said at least one membrane to said permeate side of said at least one membrane and foulants to be trapped in said at least one membrane;
• and
• intermittently cleaning said at least one membrane by causing said permeate to pass through said at least one membrane from said permeate side to said feed side, thereby dislodging foulants from said at least one membrane into said feed water at said feed side of said at least one membrane, enabling said foulants to be flushed from said feed side to a location outside of said at least one water treatment unit by reducing said feed pressure at said feed side of said at least one membrane to a pressure which is less than the osmotic pressure of said feed water at said feed side of said at least one membrane without significantly increasing the permeate pressure.