Method and device for treating low-concentration acetic acid wastewater

Abstract

The invention relates to a method and a device for treating and recovering low-concentration acetic acid wastewater generated in a pharmaceutical factory. Equipment of the whole technical flow mainly comprises a two-stage extraction tower, a stripping tower, an acetic acid treating column and corresponding auxiliary equipment thereof. The method comprises the following steps of: adding the acetic acid wastewater from the top of the two-stage extraction tower, and adding an extracting agent from the bottom of a primary extraction tower at a certain flow velocity to pass through the two-stage extraction tower; making the acetic acid-enriched extraction raffinate obtained by two-stage extraction enter the acetic acid treating column for separation, and obtaining high-purity acetic acid at the bottom of the tower, wherein the extracting agent recovered on the top of the tower can be added into an extracting agent system for recycling; making the aqueous solution which is subjected to two-stage extraction and contains a small amount of extracting agent enter the stripping tower, directly discharging the treated wastewater from the bottom of the tower, and recycling an oil phase of a phase splitter, namely the extracting agent on the top of the tower. Due to the technical treatment, the acetic acid content in the wastewater is less than 100ppm, the purity of the acetic acid is over 99.0 weight percent, and the recovery rate is over 98.0 percent.

Description

technical field [0001] The invention relates to the technical field of three wastes, in particular to a treatment process and device for low-concentration acetic acid wastewater in a pharmaceutical factory. Background technique [0002] Acetic acid is a kind of important organic chemical raw material, is widely used in industries such as basic organic synthesis, pharmaceutical chemical industry, pesticide, and its process also produces a large amount of low-concentration acetic acid wastewater (one less than 10.0, wt%), especially phthalic acid In the production process of compounds such as dimethyl terephthalate D, isophthalic acid, and cellulose acetate, many units do not pay attention to the treatment of acetic acid wastewater due to reasons such as technical processes and equipment investment, but directly Its discharge to the wastewater treatment plant not only caused great pollution to the environment, but also wasted resources. In recent years, many units and researc...

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Problems solved by technology

[0007] Chinese patent CN 1626494A discloses a method for treating furfural acetic acid wastewater in a pulse extraction tower using n-octanol as an extractant, and then using n-hexane as an entrainer to purify and separate acetic acid by intermittent azeotropic distillation. , can obtain acetic acid with a mass purity greater than 98.0%, and the concentration of acetic acid in the wastewater is less than 0.5%, but the extraction agent loss in the process is large, and the treated wastewater must not be directly discharged

[0009] Literature (Yu Lixin, Guo Qingfeng, et al.Recovery of acetic acid from dilute wastewater by means of bipolar membrane electrodialysis, Desolination, 2000, 129 (3): 283-288) has studied the separation of 3.0% by electrodialysis using anion exchange membrane About acetic acid wastewater technology can increase the concentration of acetic acid wastewater to about 40%, but the disadvantage of this process is low production capacity and high energy consumption

[0010] Among the various low-concentration acetic acid recovery methods introduced above, although the technological feasibility has been fully confirmed, the feasibility of its engineering scale-up needs further discussion and research, and there are generally low recovery efficiency and energy consumption. The shortcomings of excessively large and high concentration of acetic acid in wastewater after treatment have resulted in the need for enterprises to deal with low-concentration acetic acid wastewater that has not been well resolved.

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