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Salt-containing wastewater treatment method and system

A technology of salty wastewater and treatment method, applied in the field of salty water treatment, can solve the problems of high COD content, influence, shorten the service life of ultrafiltration membrane and reverse osmosis membrane, etc., and achieve the effect of high purity and whiteness

Active Publication Date: 2019-10-08
CHNA ENERGY INVESTMENT CORP LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, in this method, when the concentration ratio of the system is greater than 10 times, the COD content in the crystallizer is too high, and the partially refluxed crystallizer effluent has a great impact on the reverse osmosis membrane concentration system, and directly affects the purity and color of the crystallized sulfate. Spend
In addition, this method uses ferric chloride as a co-precipitant to remove scale inhibitors and organic matter, which not only increases the chemical consumption, but also mixes the effluent of the clarifier overflow tank with the co-precipitant into the membrane system, which will shorten the Service life of ultrafiltration and reverse osmosis membranes

Method used

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  • Salt-containing wastewater treatment method and system
  • Salt-containing wastewater treatment method and system
  • Salt-containing wastewater treatment method and system

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0063] This embodiment is used to illustrate the method for treating salt-containing wastewater of the present invention.

[0064] (1) Supply the saline wastewater with the water quality indicators described in Table 1 to the first softening tank 1, and use the dosing pump to reduce the Ca(OH) in the first alkali agent supply unit 7 2 The solution (with a concentration of 7% by weight) is added to the first softening tank 1, and the pH is controlled to be 11 to soften the salty wastewater to obtain the first softened effluent and slurry (sludge discharge);

[0065] (2) The first softened effluent from the first softening tank 1 and the circulating return water from the crystallizer 6 are mixed at a flow ratio of 2.5:1, and then the pH of the mixed brine is adjusted by the hydrochloric acid supplied by the acid supply unit 8 6.5, and then enter the sand filter 2 and the ultrafiltration unit 3 for sand filtration and ultrafiltration to obtain ultrafiltration effluent;

[0066] (3) Add ...

Embodiment 2

[0074] This embodiment is used to illustrate the method for treating salt-containing wastewater of the present invention.

[0075] According to the method described in Example 1, the difference is:

[0076] In step (1), the pH is controlled to be 11.5, and in step (4), the pH of the reverse osmosis concentrated water is adjusted to 11.5;

[0077] Among them, the volume flow and water quality indexes of salty wastewater, first softened effluent, ultrafiltration effluent, reverse osmosis concentrated water, reverse osmosis product water, second softened effluent and crystal effluent are shown in Table 2.

[0078] Table 2

[0079]

[0080] It can be seen from Table 2 that after the reverse osmosis concentrated water passes through the second softening tank 5, the COD is reduced by 45%, the silicon dioxide is reduced by 38%, and the magnesium ion is reduced by 90%. The second softening tank 5 treats the reverse osmosis concentrated water The effect is better. As a result, the water qualit...

Embodiment 3

[0082] This embodiment is used to illustrate the method for treating salt-containing wastewater of the present invention.

[0083] According to the method described in Example 1, the difference is:

[0084] In step (1), the pH is controlled to be 10.5, and in step (4), the pH of the reverse osmosis concentrated water is adjusted to 8.5;

[0085] Among them, the volume flow and water quality indexes of salty wastewater, first softened effluent, ultrafiltration effluent, reverse osmosis concentrated water, reverse osmosis produced water, second softened effluent and crystallized effluent are shown in Table 3.

[0086] table 3

[0087]

[0088] It can be seen from Table 3 that after the reverse osmosis concentrated water passes through the second softening tank 5, the COD is reduced by 9.8%, the silicon dioxide is reduced by 8.7%, and the magnesium ion is reduced by 8.3%. The second softening tank 5 treats the reverse osmosis concentrated water The effect is not good, and the circulating ...

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Abstract

The invention relates to the field of salt-containing wastewater treatment, in particular to a salt-containing wastewater treatment method and system. The treatment method includes the steps: taking salt-containing wastewater as raw water to be conveyed into a softening tank, and adding an alkaline agent to adjust pH (potential of hydrogen) to obtain softened water; converging the softened water and circulation backwater from a crystallizer, adding acid liquor to adjust pH, and conveying mixture into a solid-liquid separation unit to remove a solid phase to obtain solid-liquid separation water; contacting the solid-liquid separation water and a scale inhibitor, and conveying mixture into a reverse osmosis unit to obtain reverse osmosis produced water and reverse osmosis concentrated water;conveying the reverse osmosis concentrated water into the softening tank, and adding an alkaline agent to adjust pH to obtain softened water; conveying the softened water into a crystallizer to crystallize under the action of a seed crystal, separating a crystal to obtain calcium sulfate and crystal water; taking part of crystal water as circulation backwater. According to the treatment method and system, a calcium sulfate product can be prepared through efficient separation under normal-temperature crystallization and are high in purity and whiteness.

Description

Technical field [0001] The invention relates to the field of salt water treatment, and in particular to a method and system for treating salty wastewater. Background technique [0002] With the continuous improvement of environmental protection requirements, contradictions such as insufficient water resources and limited environmental capacity have become increasingly prominent. In the production process of petrochemical industry, coal chemical industry, electric power, steel and sea water desalination, a large amount of salty wastewater will be produced. In order to reduce the amount of external drainage and improve the efficiency of water use, the current salty wastewater is generally treated with reverse osmosis membranes and then reused, which improves the efficiency of water use to a certain extent. In occasions where zero liquid discharge is required, the reverse osmosis concentrated water is further used by evaporation crystallization process to obtain distilled water and...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C02F9/04C01F11/46C02F101/10
CPCC02F9/00C01F11/46C02F2101/101C02F2101/10C02F5/06C02F1/66C02F1/441C02F2301/08
Inventor 刘捷熊日华陈权霍卫东钟振成李小端马瑞张微尘
Owner CHNA ENERGY INVESTMENT CORP LTD