Water treatment process and water treatment system
First Claim
1. A water treatment process, comprising:
- a scale inhibitor supplying step of supplying a calcium scale inhibitor which is a scale inhibitor for inhibiting the deposition of a scale containing calcium and a silica scale inhibitor which is a scale inhibitor for inhibiting the deposition of silica to water containing Ca2+ ions, SO42−
ions, carbonate ions and silica;
a demineralizing step of separating the water into concentrated water in which the Ca2+ ions, the SO42−
ions, the carbonate ions and the silica are concentrated and treated water after the scale inhibitor supplying step;
a crystallizing step of supplying seed crystals of gypsum to the concentrated water so that gypsum is crystallized from the concentrated water; and
a pH adjusting step of adjusting the concentrated water to a pH of 6.0 or less, at which a scale inhibition function of the calcium scale inhibitor is reduced, thereby promoting the deposition of the gypsum in the crystallizing step.
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Accused Products
Abstract
Provided are a water treatment system and a water treatment process, which are capable of reproducing water containing salts with high water recovery. In the water treatment system (200) and the water treatment process of the present invention, after a calcium scale inhibitor and a silica scale inhibitor are supplied to water to be treated containing Ca ions, SO4 ions, carbonate ions, and silica, and the water to be treated is separated in a second demineralizing section (210) into second concentrated water in which the Ca ions, the SO4 ions, the carbonate ions, and the silica are concentrated and treated water. In a second crystallizing section (220), seed crystals of gypsum are supplied to the second concentrated water, whereby gypsum is crystallized and removed from the second concentrated water.
44 Citations
24 Claims
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1. A water treatment process, comprising:
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a scale inhibitor supplying step of supplying a calcium scale inhibitor which is a scale inhibitor for inhibiting the deposition of a scale containing calcium and a silica scale inhibitor which is a scale inhibitor for inhibiting the deposition of silica to water containing Ca2+ ions, SO42−
ions, carbonate ions and silica;a demineralizing step of separating the water into concentrated water in which the Ca2+ ions, the SO42−
ions, the carbonate ions and the silica are concentrated and treated water after the scale inhibitor supplying step;a crystallizing step of supplying seed crystals of gypsum to the concentrated water so that gypsum is crystallized from the concentrated water; and a pH adjusting step of adjusting the concentrated water to a pH of 6.0 or less, at which a scale inhibition function of the calcium scale inhibitor is reduced, thereby promoting the deposition of the gypsum in the crystallizing step. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A water treatment system, comprising:
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a scale inhibitor supplying section that supplies a calcium scale inhibitor which is a scale inhibitor for inhibiting the deposition of a scale containing calcium and a silica scale inhibitor which is a scale inhibitor for inhibiting the deposition of silica to water containing Ca2+ ions, SO42−
ions, carbonate ions and silica;a demineralizing section that is installed on a downstream side of the scale inhibitor supplying section and separates the water into concentrated water in which the Ca2+ ions, the SO42−
ions, the carbonate ions and the silica are concentrated and treated water;a crystallizing section including a crystallizing tank that is installed on a downstream side of the demineralizing section and crystallizes gypsum from the concentrated water and a seed crystal supplying section that supplies seed crystals of gypsum to the crystallizing tank; and a pH adjusting section that is installed on a downstream side of the demineralizing section and supplies a pH adjuster to the concentrated water to adjust the pH of the concentrated water to 6.0 or less such that a scale inhibition function of the calcium scale inhibitor is reduced, and the precipitation of the gypsum is promoted. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification