A method of solvent recovery from a dilute solution, comprising the following steps:
- (a) performing a first phase of solvent recovery including providing a plurality of first phase reverse osmosis units, the first phase reverse osmosis units arranged in series with one another from a first reverse osmosis unit to a last reverse osmosis unit, each of the first phase reverse osmosis units having a concentrate side, a permeate side, and a reverse osmosis membrane separating the concentrate side from the permeate side, the concentrate side of each of the first phase reverse osmosis units communicating with the concentrate side of the next reverse osmosis unit in succession, the permeate side of each of the first phase reverse osmosis units communicating with the permeate side of the preceding reverse osmosis unit in succession;
- (b) performing a final phase solvent recovery including providing at least one final phase reverse osmosis unit, the final phase reverse osmosis unit having a concentrate side, a permeate side, and a reverse osmosis membrane separating the concentrate side from the permeate side, the permeate side of the first reverse osmosis unit of the first phase reverse osmosis units communicating with the concentrate side of the final phase reverse osmosis unit;
- (c) providing at least one liquid pump, the at least one liquid pump disposed between and communicating with the permeate side of the first reverse osmosis unit of the first phase reverse osmosis units and the concentrate side of the final phase reverse osmosis unit;
- wherein
- the first phase solvent recovery includes supplying a feed stream of solvent including solute to the concentrate side of the respective first phase reverse osmosis units, forcing solvent from the concentrate side into the permeate side of the reverse osmosis units by reverse osmosis, transferring at least a portion of the concentrate in the concentrate side of the last reverse osmosis unit into the permeate side of the last reverse osmosis unit to form a mixed permeate, and successively receiving a mixed permeate in the permeate side of the reverse osmosis units preceding the last reverse osmosis unit;
- the final phase reverse osmosis includes receiving a feed stream of mixed permeate in the concentrate side of the final phase reverse osmosis unit, forcing solvent from the concentrate side into the permeate side of the final phase reverse osmosis unit, and releasing the solvent from the permeate side of the final phase reverse osmosis unit to provide solvent;
- (d) providing a nanofiltration device or an electrodialysis device communicating with at least the concentrate side of the first reverse osmosis unit of the first phase reverse osmosis units;
- (e) providing a metals and solids recovery device communicating with the nanofiltration device or the electrodialysis device;
- (f) providing a solvent recovery device communicating with the metals and solids recovery device;
- and
- (g) processing liquid through the nanofiltration device or the electrodialysis device, the metals and solids recovery device, and the solvent recovery device,
- wherein the nanofiltration device, the electrodialysis device, the metals and solids recovery device, and the solvent recovery device are disposed in series.