Recovery technology and system of PTA in alkali decrement wastewater

Abstract

The invention relates to the technical field of chemical wastewater recovery and treatment, in particular to a recovery technology and system of PTA in alkali decrement wastewater. The technology includes the steps that the alkali decrement wastewater is conveyed to a primary treatment pool, and activated carbon is added to adsorb impurities in the wastewater; then, filtration and separation are conducted through a first pressure filter to recycle the activated carbon; first primary filtration is conducted through a first filtration device, and second filtration is conducted through a second filtration device; sulfuric acid and other chemical additives are added into a third liquid storage tank, the pH value of the wastewater is primarily adjusted by adding sulfuric acid, a stirring deviceis adopted to evenly stir the wastewater to reach a stable pH value, and then sulfuric acid is added into a neutralizing treatment pool to precisely adjust the pH value; pressure filtration treatmentis conducted through a second pressure filter, and solids obtained after pressure filtration are collected to obtain polyterephthalic acid, and wastewater obtained after pressure filtration enters asewage treatment pool to be subjected to sewage treatment. By adopting the recovery technology and system of PTA in the alkali decrement wastewater, PTA can be recovered from the alkali decrement wastewater, the recovery rate is 96% or above, and the recovery purity is 97% or above.

Description

technical field [0001] The invention relates to the technical field of recovery and treatment of chemical wastewater, in particular to a process and system for recovering PTA in alkali reduction wastewater. Background technique [0002] Alkali reduction is the process of treating polyester fabrics in high temperature and relatively concentrated caustic soda. After the polyester surface is etched by strong alkali, its quality is reduced, the fiber diameter becomes thinner, pits are formed on the surface, and the shear stiffness of the fibers decreases. Eliminates the aurora of polyester filaments, and increases the gaps of fabric interweaving points, making the fabric soft to the touch, soft in luster, improved in moisture absorption and perspiration, and has a silk-like style, so the alkali reduction treatment in the printing and dyeing industry is also called imitation silk finishing . [0003] Alkali weight reduction of polyester is a complex reaction process, which mainl...

AI Technical Summary

Problems solved by technology

Alkali reduction wastewater often has the characteristics of high pH value (>12) and high COD value (>8000mg/L), and the benzene ring structure of terephthalic acid cannot be degraded by microorganisms, so it cannot be directly biochemically treated

[0004] The existing physicochemical pretreatment technology mainly has two disadvantages: one is the waste of alkali resources and the higher cost

Although the direct acid analysis method has a simple process, the obtained terephthalic acid has low purity and low utilization value, and this method directly neutralizes a large amount of alkali in the waste water with acid, and does not effectively recycle the alkali, resulting in relatively Big waste of resources

In addition, the flocculation (coagulation) acid analysis method uses materials such as organic polymer flocculation decolorizer or aluminum sulfate to pre-flocculate (coagulate) decolorize the wastewater, which improves the purity of terephthalic acid obtained by the acid analysis method, but Its cost is also high, and the aluminum hydroxide formed after coagulation with aluminum sulfate will be partial

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