Multi-stage salt separation and purification treatment system for chlor-alkali industry wastewater

Abstract

The invention discloses a multi-stage salt separation purification treatment system for chlor-alkali industry wastewater, which comprises an adjusting tank. Chlor-alkali wastewater enters a pretreatment unit through the adjusting tank, and the pretreatment unit can remove solid particles and suspended solids in the chlor-alkali wastewater and conduct COD treatment on the chlor-alkali wastewater. The pretreatment unit is connected with an anti-pollution pressure type ultrafiltration system, the anti-pollution pressure type ultrafiltration system is connected with a first-stage nanofiltration salt separation system, and the first-stage nanofiltration salt separation system can divide the chlor-alkali wastewater into monovalent sodium chloride concentrated water and bivalent sodium sulfate concentrated water. According to the method, wastewater is divided into monovalent sodium chloride concentrated water and bivalent sodium sulfate concentrated water by utilizing the selective permeability of a nanofiltration membrane to different ions, meanwhile, multi-stage salt separation is designed by the process to improve the purity of separated salt, and finally, crystallization is performed to obtain industrial-grade standard sodium chloride and sodium sulfate.

Description

technical field [0001] The invention belongs to the technical field of wastewater treatment, and in particular relates to a multi-stage salt purification treatment system for wastewater in the chlor-alkali industry. Background technique [0002] With the increasingly stringent environmental protection requirements and the increasing shortage of water resources, zero-discharge technologies such as membrane separation and evaporation crystallization have gradually emerged, and zero-discharge of wastewater has gradually been put on the agenda. However, wastewater has the characteristics of high salt content, high hardness, complex composition, and difficult treatment. Insufficient treatment of wastewater will cause waste of water resources and environmental pollution, and the cost of wastewater treatment is relatively high. [0003] At present, the wastewater treatment process in the chlor-alkali industry often only realizes zero discharge of liquid, while the soluble inorgani...

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Problems solved by technology

[0004] The purpose of the present invention is to provide a multi-stage salt purification treatment system for waste water in the chlor-alkali industry, so as to solve the problems of incomplete salt separation and environmental pollution caused by the waste water treatment process.

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