Method and apparatus for processing liquid solutions of suspensions particularly useful in the desalination of saline water

Apparatus for processing a feed liquid in the form of a solution or suspension of a first substance in a first liquid in order to reduce the concentration of said first substance in said first liquid, comprising:

• a first semipermeable body;
• means for feeding the feed liquid to one side of said first semipermeable body;
• means for feeding to the other side of said first semipermeable body an intermediate liquid which is a solution or suspension of a second substance in a second liquid to effect natural osmosis of said second liquid through said first semipermeable body, said second liquid being of the same liquid material as said first liquid, the second substance being of larger molecular weight than said first substance;
• a second semipermeable body having larger pores than said first semipermeable body;
• means for feeding the intermediate liquid from said other side of the first semipermeable body to one side of the second semipermeable body;
• and means for applying mechanical pressure to said intermediate liquid on said one side of the second semipermeable body to thereby effect reverse osmosis of the second liquid through said second semipermeable body but to reject said second substance of larger molecular size.

Apparatus for desalinating saline water, comprising:

• a first semipermeable membrane;
• means for feeding the saline water to one side of said first semipermeable membrane;
• means for feeding to the other side of said first semipermeable membrane a concentrated solution of a high molecular weight substance dissolved in water, to thereby effect, through said first semipermeable membrane, natural osmosis of water from the saline water to the concentrated solution, diluting the concentrated solutions;
• a second semipermeable body having larger pores than said first semipermeable body;
• means for feeding the so-diluted concentrated solution to one side of the second semipermeable body;
• and means for applying mechanical pressure to said diluted solution on said one side of the second semipermeable body to thereby effect reverse osmosis of water through said second permeable membrane but to reject said second substance of larger molecular size.