Method and device for separate treatment of alkali weight reduction wastewater

Abstract

The invention belongs to the technical field of water pollution control in environmental protection and relates to wastewater treatment in the printing and dyeing process, in particular to a method and a device for separately treating alkali-decrement wastewater according to the quality. The method comprises the steps as follows: 1) electrodialysis of concentrated alkali-decrement alkaline water for liquid alkali recovery: concentrated alkali-decrement alkaline water is collectively collected and pumped into an electrodialysis device, and separated regenerated alkaline water is supplemented with sodium hydroxide and reused in an alkali-decrement production link; 2) acidification and filter pressing of alkali-decrement washing wastewater and diluted electrodialysis alkaline water for separation of terephthalic acid; 3) filtrate neutralization: filtrate is neutralized until the pH ranges from 6 to 8.4 with an electrodialysis regenerated alkali liquid; 4) degradation of remaining organic matter with a biological method. According to the developed technology for separately treating alkali decrement wastewater according to the quality, alkali and terephthalic acid in the alkali-decrement production wastewater are recovered step by step, the dosage of acid and alkali is reduced, the impact of the alkali-decrement production wastewater on a biological system is reduced, and the method has the advantages that energy consumption is low, the dosage of agents is small and the like.

Description

technical field [0001] The invention belongs to the technical field of wastewater treatment, and relates to the treatment of alkali-reduction production wastewater in printing and dyeing processes, in particular to a method and device for the quality-separation treatment of alkali-reduction wastewater. Background technique [0002] The alkali reduction process is one of the important methods to improve the performance of polyester fibers. The operation method is to hydrolyze the polyester cloth under the conditions of high pressure, high temperature and high NaOH concentration. The reduction rate is generally 10-20%. This process will produce alkali reduction. amount of waste water. Most of the waste water produced is washing water, and a small part is high-concentration waste lye. Alkali reduction printing and dyeing wastewater contains a large amount of sodium terephthalate (including a large amount of incompletely hydrolyzed oligomers), ethylene glycol, sodium hydroxide,...

AI Technical Summary

Problems solved by technology

However, due to the addition of sulfuric acid, the salinity in the wastewater will be too high, and the high salinity has a great impact on the biological activity of aerobic organisms, which will greatly reduce the volume load of the aerobic biological treatment structure, and the effluent will not meet the standard.

High concentration of sulfate radicals, hydrolysis and acidification of ethylene glycol will produce malodorous gases, and waste gas treatment will increase construction costs and operating costs

[0007] In general, alkali reduction wastewater has high alkalinity, high COD, and poor biodegradability, resulting in large acid consumption and high salinity during treatment, making it difficult for the effluent to reach the standard stably

[0008] The technologies currently developed are all mixed sewage treatment technologies, which do not take into account the discharge of alkali reduction wastewater in actual operation

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