WATER TREATMENT METHOD, AND WATER TREATMENT SYSTEM

摘要

Provided are a water treatment system and a water treatment method with which salt-containing water can be recycled with a high water recovery rate. In this water treatment system (1) and water treatment method, a scale inhibitor is supplied to water to be treated including Ca ions, SO4 ions, carbonate ions, and silica, and the water to be treated is adjusted to a pH capable of dissolving silica. Having had a calcium-scale inhibitor added thereto and the pH thereof adjusted, the water to be treated is separated by a desalination unit (10) into treated water, and concentrated water in which the Ca ions, SO4 ions, carbonate ions, and silica are concentrated. In a crystallization unit (20), gypsum seed crystals are supplied to the concentrated water, and gypsum crystallizes and is removed from the concentrated water. The silica in the water to be treated is removed from the concentrated water at a downstream side of the crystallization unit (20) with respect to the water to be treated. Calcium carbonate in the water to be treated is removed from the concentrated water at an upstream side of the desalination unit (10), or at a downstream side of the crystallization unit (20).