Process for treating waste water of refined terephthalic acid

Abstract

The process of treating waste water from refined terephthalic acid production belongs to the field of environment protecting engineering and industrial effluent treating technology. The process includes settling and filtering of the waste water, oxidizing degradation in an oxidizing tower with composite catalyst, blowing aeration treatment and the next biochemical treatment. The water solution of ClO2 as the main oxidant has concentration of 0.03 %-5 % and the thrown amount of 5 %-20 % of waste water COD concentration; and the auxiliary oxidant of O2, air and / or H2O2 has the volume ratio to the waste water of 100-110 to 1. The process of the present invention has the features of small covered area, low running cost, low chemical consumption, high treating efficiency, no waste water exhaust, closed water circulation, etc.

Description

technical field [0001] The invention belongs to the technical field of environmental engineering and industrial wastewater treatment, and in particular relates to a treatment method for purified terephthalic acid production wastewater. Background technique [0002] PTA (purified terephthalic acid) is an important raw material for the production of synthetic resins, polyester fibers and other products. At present, domestic PTA devices all adopt p-xylene oxidation process. During the production process, a large amount of high-concentration organic wastewater is produced, and the composition of wastewater is complex. The main pollution Chemicals include toluene, p-xylene, p-toluic acid, p-aldehyde benzoic acid, terephthalic acid (PTA or TA), phthalic acid, benzoic acid, p-carboxybenzaldehyde, cobalt-manganese catalysts, etc. Organic pollutants and water quality are complex and changeable, which greatly increases the difficulty of treatment. However, due to the impact of market ...

AI Technical Summary

Problems solved by technology

[0002] PTA (purified terephthalic acid) is an important raw material for the production of synthetic resins, polyester fibers and other products. At present, domestic PTA devices all adopt p-xylene oxidation process. During the production process, a large amount of high-concentration organic wastewater is produced, and the composition of wastewater is complex. The main pollution Chemicals include toluene, p-xylene, p-toluic acid, p-aldehyde benzoic acid, terephthalic acid (PTA or TA), phthalic acid, benzoic acid, p-carboxybenzaldehyde, cobalt-manganese catalysts, etc. Organic pollutants and water quality are complex and changeable, which greatly increases the difficulty of treatment. However, due to the impact of market demand, the scale of PTA production equipment continues to increase, so the comprehensive treatment of PTA production wastewater is becoming increasingly urgent.

[0003] The water quality of PTA wastewater is related to its specific production technology, mainly represented by the technical routes of ICI Chemical Company of the United Kingdom and Amoco Chemical Company of the United States. The COD of PTA wastewater of the technical route of ICI Company is relatively low, generally 4000-6000mg / L, of which TA is 1000mg / L; the PTA wastewater COD of Amoco company's technical route is relatively high, generally 6000-9000mg / L, of which TA is 2000-3000mg / L. For the treatment of PTA wastewater, aerobic biological treatment is widely used in the world at present. Delayed aeration method (USA) and flocculation-biological aeration method (Japan); the former has a longer residence time (about 15 days) and occupies a larger area; the latter needs to be diluted with river water, and the process is longer. COD of waste water has dropped from 5000mg / L to 800mg / L, which is far from the standard for direct discharge. Many domestic sewage treatment plants use a combination of physical and biological methods. After pretreatment, A / O treatment, Biochemical degradation, and finally make the COD value of the wastewater reach the corresponding discharge standard and discharge. The disadvantages of this treatment method are: long residence time, large area of ​​equipment, small operation flexibility, low treatment efficiency, high comprehensive cost, sometimes due to source Fluctuations in water quality may lead to exceeding the final export water quality.

[0006] Patents such as CN1039784A, CN1176228A, and CN94118737.3 all refer to different degrees of using the metabolism of microorganisms to remove organic pollutants in wastewater, that is, traditional activated sludge method, two-stage aerobic activated sludge method and anaerobic-aerobic separation method. Stage activated sludge method. These methods can effectively treat organic waste water to a certain extent, but they also have disadvantages such as large floor area, difficult start-up and maintenance, long total hydraulic retention time, high energy consumption and the largest excess sludge, etc., which are limited. Its popularization and application in PTA wastewater treatment.

This technology achieves the effective separation of benzene series organic matter and wastewater to a certain extent, but at the same time, the resin is regenerated through repeated elution, and its adsorption efficiency is also greatly reduced, which affects its treatment capacity and is unfavorable to the operation of large devices.