Recovery of retrograde soluble solute for forward osmosis water treatment

A system for purifying contaminated water comprising:

• a semipermeable membrane comprising a feed side for receiving a contaminated feed solution stream comprising water and having a first osmotic pressure and a draw side for receiving a draw solution stream comprising a draw solute and having a second osmotic pressure, wherein the semipermeable membrane is configured to pass water from the contaminated feed solution stream to the draw side to produce a diluted draw solution stream;
• a first heat exchanger configured for heating the diluted draw solution stream;
• a coalescer configured for agglomerating the draw solute in the diluted draw solution stream to produce an agglomerated effluent stream;
• a gravity phase separator configured for separating the agglomerated draw solute from the agglomerated effluent stream to produce a water rich stream comprising water and residual draw solute and a solute rich stream comprising agglomerated draw solute and water;
• a second heat exchanger configured for cooling the water rich stream to produce a cooled single phase water rich stream;
• and
• a reverse osmosis module configured for separating the residual draw solute from the cooled single phase water rich stream to produce a residual draw solute stream and a purified water product stream.