WATER TREATMENT PROCESS AND WATER TREATMENT SYSTEM

摘要

In a water treatment system and a water treatment process, a scale inhibitor is supplied to water to be treated containing Ca ions, SO4 ions, carbonate ions, and silica, and the water to be treated is adjusted to a pH at which silica is soluble. The pH-adjusted water containing the calcium scale inhibitor is separated in a first demineralizing section into concentrated and treated water. In a first crystallizing section, seed crystals of gypsum are supplied to the first concentrated water, whereby gypsum is crystallized and removed from the first concentrated water. Silica in the water to be treated is removed from the first concentrated water on the downstream side of the first crystallizing section. Calcium carbonate in the water to be treated is removed from the first concentrated water on the upstream side of the first demineralizing section or the downstream side of the first crystallizing section.

主权项

1. A water treatment process comprising:
a first scale inhibitor supplying step of supplying a calcium scale inhibitor which is a scale inhibitor for inhibiting the deposition of a scale containing calcium to water to be treated containing Ca ions, SO4 ions, carbonate ions and silica; a first pH adjusting step of adjusting the water to be treated to a pH at which the silica is soluble in the water to be treated; a first demineralizing step of separating the water to be treated into first concentrated water in which the Ca ions, the SO4 ions, the carbonate ions and the silica are concentrated and treated water after the first scale inhibitor supplying step and the first pH adjusting step; and a first crystallizing step of supplying seed crystals of gypsum to the first concentrated water so that gypsum is crystallized from the first concentrated water, wherein the water treatment process further comprises, after the first crystallizing step: a second scale inhibitor supplying step of supplying the calcium scale inhibitor and a silica scale inhibitor which is a scale inhibitor for inhibiting the deposition of the silica to the water to be treated; a second demineralizing step of separating the water to be treated into second concentrated water in which the Ca ions, the SO4 ions, the carbonate ions and the silica are concentrated and treated water after the second scale inhibitor supplying step; and a second crystallizing step of supplying seed crystals of gypsum to the second concentrated water so that gypsum is crystallized from the second concentrated water.