Method of softening water to provide easily drained and easily filtered precipitates

Claim 2

A PROCESS OF SOFTENING WATER CONTAINING CALCIUM AND MAGNESIUM HARDNESS, AT LEAST 20% OF SAID HARDNESS BEING MAGNESIUM HARDNESS COMPRISING: A. TREATING THE WATER WITH AN EXCESS OF CALCIUM HYDROXIDE SUFFICIENT TO RAISE AND MAINTAIN THE PH OF SAID WATER TO AT LEAST 11.0 AND PASSING THE WATER UP THROUGH A FLUIDIZED BED OF GRANULAR CONTACT MATERIAL IN A FIRST VERTICAL, ELONGATED CHAMBER TO REMOVE CALCIUM AND MAGNESIUM HARDNESS AND FORM A WATER CONTAINING AN EXCESS OF CALCIUM HYDROXIDE; AND B. TREATING THE WATER CONTAINING THE EXCESS OF CALCIUM HYDROXIDE WITH A SUFFICIENT AMOUNT OF PRECIPITATING AGENT TO

Claim 3

A process in accordance with claim 1 wherein the water is treated with an aqueous solution of calcium hydroxide in the first chamber.

Claim 4

A process in accordance with claim 1 wherein the water is treated with a lime-soda solution in the first chamber.

Claim 5

A process in accordance with claim 1 wherein said precipitating agent is carbon dioxide.

Claim 6

A process in accordance with claim 1 further comprising passing the precipitate recovered by filtering, into the vertical elongated chambers to provide a source of granular contact material in the fluidized bed of said chamber.

Claim 7

A process in accordance with claim 1 further comprising treating the precipitate recovered by filtering, with carbon dioxide to form water-soluble calcium bicarbonate and passing said calcium bicarbonate into the first vertical elongated chamber where it is precipitated on granular contact material by the calcium hydroxide.

Claim 8

A process in accordance with claim 1 further comprising treating the precipitate recovered by filtering, with a sufficient amount of an inorganic acid to neutralize the precipitate and returning said neutralized solution to said first vertical elongated chamber.

Claim 9

A process in accordance with claim 7 wherein the inorganic acid is selected from the group consisting of hydrochloric acid, nitric acid, sulfuric acid and phosphoric acid.

Claim 10

A process of softening raw water containing calcium and magnesium hardness with chemical agents to provide easily drained and filterable precipitates, in an apparatus comprising a first inverted, frusto-conical tank having at least one tangential raw water inlet, a chemical inlet and a blowdown outlet near the bottom of said tank and a water outlet near the top of said tank; a second inverted frusto-conical tank having at least one tangential treated water inlet, a gas inlet and blowdown outlet near the bottom of said tank and a water outlet near the top of said tank, the treated water inlet of said second tank communicating with the water outlet of said first tank; and a filter the inlet of which communicates with the water outlet of said second tank and the outlet of which passes to service, which process comprises: a. feeding raw water containing calcium and magnesium hardness, at least 20 percent of said hardness being magnesium hardness, into said first inverted, frusto-conical tank; b. feeding an amount of chemical softening agent selected from the group consisting of lime and lime-soda ash sufficient to raise and maintain the pH of said raw water to at least 11.0 in said chemical inlet; c. passing said raw water and chemical softening agent in a turbulent flow pattern in said first frusto-conical tank in the presence of granular contact material suspended in said raw water by the turbulent flow pattern to mix said raw water, chemical softening agent and granular contact material and thereby form a precipitate from the calcium and magnesium hardness and a hardness-depleted water containing excess chemical softening agent; d. passing the hardness-depleted water containing excess chemical softening agent from the water outlet of said first tank and feeding said hardness-depleted water into said second tank; e. feeding a sufficient amount of carbon dioxide to reduce and maintain the pH of the hardness-depleted water to a range from about 9.8 to about 10.2 into said gas inlet of said second tank; f. passing said hardness-depleted water and carbon dioxide in a turbulent flow pattern in said second frusto-conical tank in the presence of granular contact material suspended in said water by the turbulent flow pattern to mix said hardness-depleted water, carbon dioxide and granular contact material and thereby form a precipitate from the excess chemical softening agent in said hardness-depleted water said precipitate forming on said granular contact material, and a softened water; and g. passing the softened water from the water outlet of said second tank to said filter to remove solid particles carried with the softened water from said second tank whereby the easily filtered precipitate carried out of said second tank is removed from the softened water by said filter and an easily drained precipitate adhering to the granular contact material in the first and second frusto-conical tanks is removed from the respective blowdown outlets in said tanks.

Claim 11

A process of softening raw water containing calcium and magnesium hardness with chemical agents to provide easily drained and filterable precipitates, in an apparatus comprising a first inverted, frusto-conical tank having at least one tangential raw water inlet, a chemical inlet and a blowdown outlet near the bottom of said tank and a water outlet near the top of said tank; a second inverted frusto-conical tank having at least one tangential treated water inlet, a gas inlet and blowdown outlet near the bottom of said tank and a water outlet near the top of said tank, the treated water inlet of said second tank communicating with the water outlet of said first tank; and a filter the inlet of which communicates with the water outlet of said second tank and the outlet of which passes to service, which process comprises: a. feeding raw water containing calcium and magnesium hardness, at least 20 percent of said hardness being magnesium hardness, into said first inverted, frusto-conical tank; b. feeding an amount of chemical softening agent selected from the group consisting of lime and lime-soda ash sufficient to raise and maintain the pH of said raw water to at least 11.0 in said chemical inlet; c. passing said raw water and chemical softening agent in a turbulent flow pattern in said first frusto-conical tank in the presence of granular contact material suspended in said raw water by the turbulent flow pattern to mix said raw water, chemical softening agent and granular contact material and thereby form a precipitate from the calcium and magnesium hardness and a hardness-depleted water containing excess chemical softening agent; d. passing the hardness-depleted water containing excess chemical softening agent from the water outlet of said first tank and feeding said hardness-depleted water into said second tank; e. feeding a sufficient amount of carbon dioxide to reduce and maintain the pH of the hardness-depleted water to a range from about 9.8 to about 10.2 into said gas inlet of said second tank; f. passing said hardness-depleted water and carbon dioxide in a turbulent flow pattern in said second frusto-conical tank in the presence of granular contact material suspended in said water by the turbulent flow pattern to mix said hardness-depleted water, carbon dioxide and granular contact material and thereby form a precipitate from the excess chemical softening agent in said hardness-depleted water said precipitate forming on said granular contact material, and a softened water; and g. passing the softened water from the water outlet of said second tank to said filter to remove solid particles carried with the softened water from said second tank whereby the easily filtered precipitate carried out of said second tank is removed from the softened water by said filter and an easily drained precipitate adhering to the granular contact material in the first and second frusto-conical tanks is removed from the respective blowdown outlets in said tanks.

Claim 12

A process in accordance with claim 9 further comprising passing the precipitate recovered by filtering into the inverted, frusTo-conical tanks to provide a source of granular contact material.

Claim 13

A process in accordance with claim 9 further comprising treating the precipitate recovered by filtering with carbon dioxide to form water-soluble calcium bicarbonate and passing said calcium bicarbonate into the first inverted, frusto-conical tank where it is precipitated on granular contact material by the softening chemical.

Claim 14

A process in accordance with claim 9 further comprising treating the precipitate recovered by filtering with a sufficient amount of an inorganic acid to neutralize the precipitate and returning said neutralized solution to said first inverted, frusto-conical tank.