Method for high efficiency reverse osmosis operation

  • US 8,641,905 B2
  • Filed: 03/12/2013
  • Issued: 02/04/2014
  • Est. Priority Date: 08/12/1996
  • Status: Expired due to Fees
First Claim
Patent Images

1. A process for treatment of a feedwater stream in membrane separation equipment, said membrane separation equipment comprising a number N of membrane separation units, N being a positive integer, to produce a low solute containing product stream and a high solute containing reject stream, said process comprising:

  • (a) providing a feedwater stream containing solutes therein, said solutes comprising (i) hardness, (ii) alkalinity, and (iii) at least one molecular species which is sparingly ionized when in neutral or near neutral pH aqueous solution, said at least one molecular species comprising one or more of (1) at least some TOC, or (2) at least some silica, or (3) at least some boron;

    (b) effectively eliminating the tendency of said feedwater to form scale when said feedwater is concentrated to a preselected concentration factor at a selected pH, by effecting, in any order, two or more of the following;

    (i) removing hardness from said feedwater stream;

    (ii) removing substantially all non-hydroxide alkalinity from said feedwater stream;

    (iii) removing dissolved gases, whether initially present or created during said hardness or said alkalinity removal step;

    (c) raising the pH of the product from step (b) to a selected pH of at least about 8.5 by adding a selected base thereto, to urge said at least one molecular species which is sparingly ionized when in neutral or near neutral pH aqueous solution toward increased ionization;

    (d) passing the product from step (c) above through N1, the first one of said membrane separation units, said membrane separation equipment substantially resisting passage of dissolved species therethrough, to concentrate said feedwater to said preselected concentration factor, to produce (i) said high solute containing reject stream, and (ii) said low solute containing permeate product stream, and (iii) wherein TOC in said product stream is less than five percent (5%) of said at least some TOC in said feedwater.

View all claims
    ×
    ×

    Thank you for your feedback

    ×
    ×