WATER TREATMENT PROCESS AND WATER TREATMENT SYSTEM

摘要

A water treatment method and a water treatment system that are capable of treating water containing salts to allow recovery of treated water at a high ion removal rate and a high water recovery rate, and allow recovery of high quality gypsum are provided. In the water treatment system, the water to be treated containing Ca2+ and SO42− is separated into concentrated water in which Ca2+ and SO42− are concentrated and treated water containing CO2 in a first demineralizer so that the treated water is recovered. The concentrated water in the first demineralizer is adjusted to a pH at which calcium carbonate can be dissolved and the scale inhibition function of a scale inhibitor is reduced, and then is delivered to a crystallizing tank. In the crystallizing tank, gypsum is crystallized from the concentrated water in the first demineralizer. The gypsum is separated and recovered in a separating section.

主权项

1. A water treatment process comprising:
a scale inhibitor supplying step of supplying a scale inhibitor to water to be treated containing Ca ions, SO4 ions and carbonate ions; an upstream side separating step of separating the water to be treated into concentrated water in which the Ca ions and the SO4 ions are concentrated and treated water containing CO2, in a first demineralizer, and recovering the treated water; a first pH adjusting step of adjusting the concentrated water in the first demineralizer to a pH at which calcium carbonate is soluble and a scale inhibiting function of the scale inhibitor is reduced so that gypsum is deposited from the concentrated water in the first demineralizer; a crystallizing step of crystallizing crystals of the gypsum from the concentrated water in the first demineralizer having the adjusted pH; and a recovering step of separating and recovering the crystals from the concentrated water in the first demineralizer.