Patent ID: 7938956

Claim:
A water purification system comprising: a pump having an aspiration side adapted to aspirate water to be purified and a discharge side adapted to discharge under pressure water entering the pump; a liquid phase separator operating by permeation through at least one selective permeability membrane as a result of a pressure gradient and having an inlet in fluid communication with the discharge side of the pump, a permeate outlet, and a retentate outlet; an electrodeionization unit having a permeate inlet in fluid communication with said permeate outlet of said separator and a purified water outlet; an evacuation stream for evacuating the retentate from the system to a system drainage outlet, in fluid communication with the retentate outlet of said separator, and incorporating a restriction to reduce the retentate flowrate in the vicinity of the drainage outlet of the system; and a recirculating stream whereby the evacuation stream communicates with said aspiration side of said pump, between the retentate outlet of the separator and said restriction and incorporating a pressure regulator to maintain, (i) in conjunction with said pump, a substantially constant predetermined pressure across said restriction so as to obtain a constant reverse osmosis retentate flow to waste regardless of the feed pressure, and (ii) in conjunction with said restriction, a constant predetermined pressure at said inlet of said separator, so as to maintain a substantially constant predetermined retentate flowrate to waste independently of the water temperature.