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Multi-stage countercurrent electrodialyzer reversal-based method for treating saline wastewater in coal chemical industry

A technology of inverted electrodialysis and saline wastewater, which is applied in the fields of water/sewage multi-stage treatment, chemical instruments and methods, water/sludge/sewage treatment, etc. High cost and other issues, to achieve the effects of prolonged membrane cleaning cycle, high fresh water recovery rate, and high fresh water yield

Active Publication Date: 2014-09-03
INST OF PROCESS ENG CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method can avoid the problems of low fresh water recovery rate, low concentration multiple, high operating cost, serious membrane fouling and unstable system operation in the treatment of coal chemical industry saline wastewater by conventional ultrafiltration-reverse osmosis technology. Engineering application of advanced treatment and desalination of saline wastewater

Method used

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  • Multi-stage countercurrent electrodialyzer reversal-based method for treating saline wastewater in coal chemical industry
  • Multi-stage countercurrent electrodialyzer reversal-based method for treating saline wastewater in coal chemical industry

Examples

Experimental program
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Effect test

Embodiment 1

[0037] Example 1 Simulation of Electrodialysis Desalination of Coal Chemical Industry Salt Wastewater

[0038] Electrodialysis technology was used to treat simulated coal chemical industry saline wastewater, and the effects of different initial Cl- ions in concentrated water and fresh water on desalination rate, energy consumption and membrane stack voltage were investigated. Studies have shown that when the initial concentration of Cl- in fresh water is 600 mg / L, and the initial concentration of concentrated water is 1200, 5000 and 8000 mg / L, under constant pressure conditions, the resistance increases with the reduction of the salt content of fresh water, which can lead to The current density drops. In 150 minutes, the concentration of Cl- ions in fresh water can be reduced to below 250 mg / L. When the concentration of Cl- ions in concentrated water is high, the removal rate of Cl- ions slows down. The reason is speculated to be the reverse diffusion of Cl- ions in concentrat...

Embodiment 2

[0039] Example 2 Electrodialysis desalination of actual coal chemical industry saline wastewater

[0040]Taking the external drainage of the biological aerated filter in the coal chemical industry as an example, although it has reached the industrial wastewater discharge standard, its recycling is limited due to the presence of inorganic salts such as Cl- ions, a small amount of refractory organic matter, suspended particles and bacteria, etc. Remove inorganic ions such as Cl- and other pollutants. Electrodialysis technology is used for desalination treatment, and constant potential operation is adopted. Concentrated water and fresh water are filtered with 5 μm PP cotton and then directly used as water for electrodialysis system. Wastewater is similar, and under the same desalination conditions, the Cl-ion in fresh water drops to less than 250mg / L to meet the reuse standard. However, in each batch of experiments, the current density showed a downward trend with the desalinati...

Embodiment 3

[0042] Example 3 Multi-stage countercurrent reverse electrode electrodialysis treatment of actual coal chemical industry salty wastewater

[0043] Aiming at the external drainage of coal chemical aerated biological filter of large-scale iron and steel enterprises in China (referred to as coal chemical saline wastewater), although the discharge standard has been met, the wastewater still contains a small amount of refractory organic matter, soluble inorganic salts, Ca 2+ and Mg 2+ Ions, suspended solids, colloids, chroma and other impurities, etc., are directly treated by multi-stage countercurrent reverse electrode electrodialysis after sand filtration. After the system has been in operation for 5 days, it is found that the current density gradually decreases under the same applied voltage, resulting in the desalination rate of electrodialysis. The desalination rate per unit of wastewater is also greatly reduced, and the membrane resistance is significantly increased, making i...

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Abstract

The invention relates to the field of industrial wastewater treatment processes and provides a multi-stage countercurrent electrodialyzer reversal-based method for treating saline wastewater in the coal chemical industry. The method comprises the following steps: 1) carrying out catalytic ozonation treatment on the saline wastewater in the coal chemical industry; 2) carrying out multi-media filtration and membrane filtration treatment on the wastewater subjected to catalytic ozonation in the step 1) in sequence; and 3) treating the effluent obtained after membrane filtration in the step 2) with a multi-stage countercurrent electrodialyzer reversal, thus achieving deep treatment, desalting and recycling of the saline wastewater in the coal chemical industry, wherein the multi-stage countercurrent electrodialyzer reversal comprises an electrodialysis membrane stack unit, a frequency reversal control unit and an online monitoring and process control unit. The method has the advantages of high fresh water recovery rate, low concentrated water discharge, low operating cost, stability in system operation and the like and can avoid the problems of low fresh water recovery rate, low concentration multiple, high treatment cost, serious membrane pollution, instability in system operation and the like in the routine techniques.

Description

technical field [0001] The invention relates to the field of industrial wastewater treatment technology, in particular, the invention relates to a method for treating salty wastewater in coal chemical industry based on a multi-stage countercurrent inverted electrode electrodialyzer. Background technique [0002] Coal chemical industry saline wastewater mainly comes from coal gas washing wastewater, circulating water system drainage, chemical water station drainage, etc. in the production process, and sometimes organic wastewater after biochemical treatment, which is characterized by high salt content, pollutants with total salt content Most of the waste water contains refractory organic matter. The TDS of this kind of wastewater is usually around 5000mg / L, or even higher, and cannot be reused directly. At present, although this type of industrial wastewater has reached the environmental protection discharge standard, the water contains NaCl, Na 2 SO 4 , CaCl 2 , MgSO 4 ...

Claims

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Application Information

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IPC IPC(8): C02F9/06C02F1/469
Inventor 石绍渊曹宏斌李玉平盛宇星
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI
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