PTA mother liquor recovery treatment method based on membrane technology

Abstract

The invention discloses a PTA mother liquor recovery treatment method based on a membrane technology, and belongs to the technical field of chemical wastewater treatment, and the PTA mother liquor recovery treatment method comprises the following steps: (1) carrying out membrane distillation separation on a PTA mother liquor to be treated through a hydrophobic filter membrane to obtain reclaimed water and a concentrated solution; (2) performing membrane filtration on the concentrated solution through an ultrafiltration membrane to remove impurities, and recovering solid content to obtain low solid liquid; (3) performing impurity removal and recovery of metal ions on the low-solid liquid, performing anaerobic treatment on the recovered wastewater, and discharging the wastewater; according to the method, the heat carried by the PTA mother liquor wastewater is utilized, the mother liquor is concentrated and crystallized through the membrane distillation process of the hydrophobic filter membrane, most solid content in the concentrated liquor is removed through the ultrafiltration membrane separation so as to make full use of various organic acids, then the cobalt-manganese catalyst is recycled, and finally the wastewater is subjected to anaerobic treatment. And various organic compounds in the wastewater are fully recovered.

Description

technical field [0001] The invention relates to the technical field of chemical wastewater treatment, in particular to a method for recycling PTA mother liquor based on membrane technology. Background technique [0002] Purified terephthalic acid (PTA) is an important chemical raw material, which is widely used in polyester industrial production. Since the 1980s, the market demand for PTA has increased sharply, resulting in a rapid increase in PTA production capacity, which has also led to the development of PTA wastewater treatment technology. [0003] At present, PTA is usually prepared by catalytic oxidation of p-xylene (PX) at high temperature and high pressure, and then refined. In the PTA production process, it is necessary to extract part of the oxidation mother liquor to remove metal impurity ions and organic by-products to improve product quality. Generally, the extraction ratio of the oxidation mother liquor is (8-15)%. The COD in this part of the wastewater is ...

AI Technical Summary

Problems solved by technology

In the PTA production process, part of the oxidation mother liquor needs to be extracted to remove metal impurity ions and organic by-products to improve product quality. Generally, the extraction ratio of the oxidation mother liquor is (8-15)%. The COD in this part of the wastewater is about 4500-8000mg / L. The temperature generally exceeds 50°C, the highest temperature can reach 80°C-90°C, and the pH range is 2-3. In addition to a large amount of acetic acid solvent, it also contains terephthalic acid, p-toluic acid, benzoic acid, cobalt, and manganese. Catalysts and other impurities are a system with very high added value, but due to the complex composition of wastewater and poor biochemical ability, it is difficult to use conventional wastewater treatment methods for treatment

At present, most of the PTA production enterprises at home and abroad only recycle the acetic acid solvent, and then incinerate the oxidation residue, or recycle the cobalt-manganese catalyst, but whether it is the general PTA wastewater treatment method or the catalyst cobalt-manganese recovery method It is impossible to recycle a variety of useful substances in wastewater by only targeting the removal of a certain substance, which is likely to cause serious waste of resources