×

Purification of saline water

  • US 4,036,749 A
  • Filed: 11/08/1976
  • Issued: 07/19/1977
  • Est. Priority Date: 04/30/1975
  • Status: Expired due to Term
First Claim
Patent Images

1. A method for selectively removing calcium salts from raw water containing dissolved salts, including calcium bicarbonate, in a total amount no greater than about 10,000 parts per million, and for purifying the water wherein said dissolved salts in said raw water are concentrated in a residual portion during said purification thereof to a content approaching their solubility limits at the purification processing conditions, which comprises the following sequential steps for reducing the volume of said residual portion:

  • a. adding magnesium hydroxide precipitant to the raw water in an amount sufficient to precipitate calcium carbonate settling said precipitate, and recovering a treated water having a substantially reduced dissolved calcium content that said raw water and passing said treated water to said processing;

    b. processing said treated water to separate a purified water from a residual water enriched with salts by reverse osmosis, distillation, electrodiaylsis or freezing;

    c. adding calcium hydroxide to at least a portion of the residual water from said processing in an amount sufficient to precipitate soluble magnesium values in said waste brine as insoluble magnesium hydroxide; and

    d. separating magnesium as magnesium hydroxide from said waste brine and returning the separated magnesium hydroxide as substantially the entirity of the precipitant to step (a).

View all claims
  • 0 Assignments
Timeline View
Assignment View
    ×
    ×