Patent ID: 6645383
Filing Date: 2003-11-11
Classification: B01D,C02F

Abstract:
A process for membrane separation of a supply of potable tap water for obtaining a treated drinking water product having desired taste characteristics, comprising:selecting at least one nanofiltration primary membrane from a plurality of nanofiltration primary membranes; selecting at least one reverse osmosis secondary membrane from a plurality of reverse osmosis secondary membranes; feeding said tap water to said selected at least one nanofiltration primary membrane, said at least one primary membrane separating said water into a primary membrane retentate retained by said at least one primary membrane, and a primary membrane permeate; feeding said primary membrane retentate directly to said selected at least one reverse osmosis secondary membrane, said at least one secondary membrane separating said primary membrane retentate into a secondary membrane retentate retained by said at least one secondary membrane, and a secondary membrane permeate; and blending said primary membrane permeate and said secondary membrane permeate to form a product drinking water by directly passing said primary membrane permeate and said secondary membrane permeate to a permeate blending point; wherein a solute concentration of said primary membrane permeate is greater than a solute concentration of said secondary membrane permeate, and said blending of permeates having distinct concentrations creates a drinking water product having desired taste characteristics without adding supplemental minerals or untreated water post treatments, said desired taste characteristics being represented by a hardness value in the approximate range of between 20-100 ppm and an alkalinity value in the approximate range of between 21 and 100 ppm, said process including varying the number of at least one of said at least one nanofiltration primary membranes and said at least one reverse osmosis secondary membranes to achieve taste characteristics in said range.