Abstract: A process for operating a cooling tower (10) comprising: introducing a feed solution into a cooling tower, evaporating solvent from the feed solution to produce a concentrated solution, removing a portion of the concentrated solution as blow-down, passing a portion of the blow-down through a first membrane, such that some of the solute in the blow-down are retained as a concentrated blow-down solution on the retentate-side of the first membrane, contacting a portion of the concentrated blow-down solution (42) with one side of a second membrane (12) and contacting a solution having a lower solute concentration than the combined concentrated blow-down solution and the return from the cooling tower with the opposite side of the second membrane, such that solvent flows across the second membrane to dilute the concentrated blow-down solution by direct osmosis, and re-introducing the diluted blow-down solution to the cooling tower.

Abstract: A thermal desalination process comprising: introducing a feed solution into a thermal separation unit, distilling the feed solution in the thermal separation unit to produce a distillate stream and a residual stream having a higher solute concentration than the feed solution, contacting a portion of the residual stream from the thermal separation unit with one side of a selectively permeable membrane, contacting the opposite side of the selectively permeable membrane with a portion of the feed solution, such that water flows across the membrane to dilute the residual stream by direct osmosis, and introducing at least a portion of the diluted residual stream into the thermal separation unit.

Abstract: A process for operating a cooling tower (10), said process comprising: introducing a feed solution into a cooling tower, evaporating solvent from the feed solution to produce a concentrated solution, removing a portion of the concentrated solution as blow-down, passing at least a portion of the blow-down through a first membrane in a nanofiltration unit (14), such that at least some of the solute in the blow-down are retained as a concentrated blow-down solution on the retentate-side of the first membrane, contacting at least a portion of the concentrated blow-down solution (42) with one side of the second membrane (12) and contacting a solution having a lower solute concentration than the combined concentrated blow-down solution and the return from the cooling tower with the opposite side of the second membrane, such that solvent flows across the second membrane to dilute the concentrated blow down solution by direct osmosis, and re-introducing the diluted blow-down solution to the cooling tower.

Abstract: A process for operating a cooling tower (10), said process comprising: introducing a feed solution into a cooling tower, evaporating solvent from the feed solution to produce a concentrated solution, removing a portion of the concentrated solution as blow-down, passing at least a portion of the blow-down through a first membrane in a nanofiltration unit (14), such that at least some of the solute in the blow-down are retained as a concentrated blow-down solution on the retentate-side of the first membrane, contacting at least a portion of the concentrated blow-down solution (42) with one side of a second membrane (12) and contacting a solution having a lower solute concentration than the combined concentrated blow-down solution and the return from the cooling tower with the opposite side of the second membrane, such that solvent flows across the second membrane to dilute the concentrated blow down solution by direct osmosis, and re-introducing the diluted blow-down solution to the cooling tower.

Abstract: A process for removing a solvent from a source solution, said process comprising a) contacting the source solution with one side of a selectively permeable membrane, b) contacting a draw solution having a higher osmotic pressure (higher solute concentration) than the source solution with the opposite side of the membrane, such that solvent from the source solution passes across the membrane to dilute the draw solution by direct osmosis, c) removing solvent from the diluted draw solution to regenerate the draw solution, and d) recycling the regenerated draw solution to step a), characterized in that a portion of the draw solution is discarded or treated before and/or after the draw solution is regenerated in step c) so as to reduce the concentration of any solute species present in the draw solution from the source solution.

Abstract: A process for removing a solvent from a source solution, said process comprising a) contacting the source solution with one side of a selectively permeable membrane, b) contacting a draw solution having a higher osmotic pressure (higher solute concentration) than the source solution with the opposite side of the membrane, such that solvent from the source solution passes across the membrane to dilute the draw solution by direct osmosis, c) removing solvent from the diluted draw solution to regenerate the draw solution, and d) recycling the regenerated draw solution to step a), characterised in that a portion of the draw solution is discarded or treated before and/or after the draw solution is regenerated in step c) so as to reduce the concentration of any solute species present in the draw solution from the source solution.

Abstract: A thermal desalination process comprising: introducing a feed solution into a thermal separation unit, distilling the feed solution in the thermal separation unit to produce a distillate stream and a residual stream having a higher solute concentration than the feed solution, contacting a portion of the residual stream from the thermal separation unit with one side of a selectively permeable membrane, contacting the opposite side of the selectively permeable membrane with a portion of the feed solution, such that water flows across the membrane to dilute the residual stream by direct osmosis, and introducing at least a portion of the diluted residual stream into the thermal separation unit.

Abstract: A process for operating a cooling tower (10), said process comprising: introducing a feed solution into a cooling tower, evaporating solvent from the feed solution to produce a concentrated solution, removing a portion of the concentrated solution as blow-down, passing at least a portion of the blow-down through a first membrane in a nanofiltration unit (14), such that at least some of the solute in the blow-down are retained as a concentrated blow-down solution on the retentate-side of the first membrane, contacting at least a portion of the concentrated blow-down solution (42) with one side of a second membrane (12) and contacting a solution having a lower solute concentration than the combined concentrated blow-down solution and the return from the cooling tower with the opposite side of the second membrane, such that solvent flows across the second membrane to dilute the concentrated blow down solution by direct osmosis, and re-introducing the diluted blow-down solution to the cooling tower.