Treating and recycling process of acid wastewater generated in disperse dye production

Abstract

The invention discloses a treating and recycling process of acid wastewater generated in disperse dye production. The process comprises the steps of collecting acid wastewater generated by a same disperse dye, and separately collecting mother liquor water and washing water; adding at least one of magnesium oxide, magnesium hydroxide and magnesium carbonate to the collected mother liquor water and washing water, and adjusting the pH value to be 7-8; adding solid soda to the wastewater after adjustment until the pH value of the wastewater is 9-12, thereby obtaining first filtrate and first filter residues; adding a mixture of aluminium trichloride and solid soda to the first filtrate, thereby obtaining second filtrate and second filter residues; recycling part of the second filtrate in washing of dye filter cakes, carrying out condensation crystallization on the remaining filtrate, and recycling the condensed water. According to the process, recycling of the wastewater and magnesium is achieved by neutralizing acid water generated in the dye and intermediate production process by utilizing magnesium oxide, magnesium hydroxide or magnesium carbonate and then precipitating magnesium ions with solid soda, therefore, the process meets the requirement for clean production of resources.

Description

technical field [0001] The invention relates to the technical field of wastewater treatment, in particular to a process for treating and recycling acidic wastewater in the production process of disperse dyes. Background technique [0002] Azo disperse dyes are generally produced through diazotization and coupling reactions between aniline derivatives. Therefore, dye wastewater usually contains toxic and harmful substances such as aniline derivatives, as well as inorganic or organic acids such as sulfuric acid, hydrochloric acid, phosphoric acid, and acetic acid. and inorganic salts such as sodium chloride or sodium sulfate. A large amount of acidic wastewater generated in the dye production process not only has high salinity and high COD value, but also has a chromaticity of several tens of times. At the same time, due to its low biodegradability, direct treatment and discharge will cause serious harm to the environment. At present, most enterprises first use calcium carbid...

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Problems solved by technology

[0004] For example, the patent document CN102826673A discloses a cleaning treatment method for dye industrial acid wastewater. After the wastewater is purified by neutralization, decolorization, oxidation, concentration, separation and other measures, it can be reused as synthetic bottom water for dye production and dye filter cake washing water. Abandoning the discharge of a large amount of colored and high COD value wastewater in the traditional dye production process, this patent document uses liquid ammonia to replace the current lime or calcium carbide slag for waste acid neutralization in wastewater treatment, solving the landfill of hazardous solid waste and sulfuric acid Calcium slag is difficult to deal with, but the risk factor of large-scale storage and transportation of liquid ammonia is extremely high. At the same time, the solubility of ammonium sulfate does not change much with temperature, and the temperature difference between cooling and crystallization needs to be relatively large, and it is accompanied by high-concentration ammonia nitrogen wastewater.

[0005] Patent document CN101412571A discloses a waste water recycling process in the production of azo dyes. A large amount of mother liquor waste water and washing waste water generated in the dye production process are treated and reused for washing filter cakes, which reduces waste water discharge to a certain extent. , but did not really achieve zero discharge of wastewater

[0006] Another patent document CN103214116A realizes the recycling of sulfuric acid-containing wastewater, but in the process, the calcium sulfate produced by neutralizing the waste acid needs to be calcined and other post-treatments, which increases the number of treatment steps and increases the treatment cost to a certain extent.

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