Desulfurization wastewater treating method and device

Abstract

The invention relates to the field of wastewater treatment, in particular to a desulfurization wastewater treating method and device. The desulfurization wastewater treating method comprises the steps that softening pretreatment is conducted on clear liquid obtained through flocculation treatment and alkali carbonate to obtain calcium carbonate precipitate and softened desulfurization wastewater; nanofiltration treatment is conducted on the softened desulfurization wastewater to obtain sulfuric-acid-rich salt water and sulfuric-acid-deficient salt water; reverse osmosis treatment is conducted the sulfuric-acid-deficient salt water to obtain first chlorine-rich concentrated water and first fresh water; electrodialysis treatment is conducted on the chlorine-rich concentrated water to obtain second chlorine-rich concentrated water and second fresh water; evaporation crystallization treatment is conducted on the second chlorine-rich concentrated water to obtain chlorine salt and third fresh water, wherein the nanofiltration treatment is cyclically conducted on the sulfuric-acid-rich salt water and the softened desulfurization wastewater. By the adoption of the method, wastewater produced after flue gas desulfurization of coal-fired power plants and the like can be effectively treated, the treated wastewater can be resourcefully utilized, the cost for removing and recovering chlorine-containing salt can be reduced, and more purified water can be obtained.

Description

technical field [0001] The invention relates to the field of wastewater treatment, in particular to a treatment method and device for desulfurization wastewater. Background technique [0002] Coal-fired power plant water is the largest industrial water industry in my country, accounting for about 30-40% of the total industrial water use. In order to improve the comprehensive utilization rate of water, power plants generally use various types of drainage such as reverse osmosis concentrated water and circulating water sewage as process water sources for wet desulfurization systems. Desulfurization wastewater has become the worst wastewater at the end of coal-fired power plants, and it is also a key constraint factor for the zero discharge of wastewater in the whole plant. [0003] Desulfurization wastewater has the characteristics of high salt content, high suspended solids and chloride ion content, high hardness, strong acid corrosion and easy scaling. At present, the conv...

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Problems solved by technology

[0007] The purpose of the present invention is to provide a low-cost, high water resource utilization and better desalination method for the defects of the existing desulfurization wastewater treatment methods, such as high cost, low water resource utilization rate and difficulty in desalination. Method and device for treating desulfurization wastewater from removing and recovering salt

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