A method for resource-based treatment of dyeing and printing wastewater containing caustic soda

By treating caustic soda-containing wastewater from printing and dyeing using electro-driven membrane separation and bipolar membrane electrodialysis technology, the problems of unrecoverable caustic soda and low-quality terephthalic acid have been solved, realizing the resource utilization of caustic soda and the efficient recovery of terephthalic acid, and reducing treatment costs.

CN122403679APending Publication Date: 2026-07-17刘伟斌
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
刘伟斌
Filing Date
2026-05-14
Publication Date
2026-07-17

AI Technical Summary

Technical Problem

In the existing technology for treating dyeing and printing wastewater, caustic soda cannot be recovered and reused, and the quality of terephthalic acid by-products is low, resulting in a large consumption of sulfuric acid and an increased load on biochemical treatment.

Method used

An electrically driven membrane separation device and a bipolar membrane electrodialysis device are used to treat dyeing and printing wastewater containing caustic soda through solid-liquid separation and electrodialysis, recover the alkali solution and control the crystallization conditions to precipitate terephthalic acid, thereby improving the quality of by-products.

Benefits of technology

This approach enables the recycling and reuse of caustic soda, reduces the consumption of purchased caustic soda, improves the purity and filtration efficiency of terephthalic acid, reduces the amount of sulfuric acid used, and lowers wastewater treatment costs.

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Abstract

This invention discloses a resource-based treatment method for dyeing and printing wastewater containing caustic soda, relating to the field of wastewater treatment, comprising the following steps: S1, collecting pre-shrinking wastewater, desizing wastewater, and alkali reduction wastewater separately; S2, performing solid-liquid separation pretreatment on at least one of the collected pre-shrinking wastewater, desizing wastewater, and alkali reduction wastewater to obtain a pretreated clear liquid; S3, passing the pretreated clear liquid into an electrically driven membrane separation device to separate and obtain a recovered alkali solution and a dealkali-reducing brine; S4, adding sulfuric acid to the dealkali-reducing brine, precipitating terephthalic acid solid under controlled crystallization conditions, and obtaining coarse-particle terephthalic acid and sodium sulfate solution through solid-liquid separation; S5, passing the sodium sulfate solution obtained in step S4 into a bipolar membrane electrodialysis device to prepare a sulfuric acid solution and a sodium hydroxide solution; This method, through an electrically driven membrane separation device, pre-recovers free alkali in the wastewater before acid neutralization, and the recovered caustic soda can replace part of the purchased liquid alkali for reuse in production or wastewater treatment.
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