Chromium-containing waste water treating and chromium recycling method

A technology for chromium wastewater and chromium recovery, applied in water/sewage treatment, chemical instruments and methods, and neutralized water/sewage treatment, etc., can solve the problems of unrecyclable chromium resources, high cost, and complicated processes

Inactive Publication Date: 2018-09-28
UNIV OF SCI & TECH BEIJING +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] Although the chemical flocculation precipitation method or the magnetic seed enhanced chemical flocculation precipitation method can effectively remove chromium in chromium-containing wastewater, and the chromium content in wastewater can meet the national discharge standards, but the biggest drawback of this method is that chromium is removed from chromium-containing waste together with other wastes. It settles down in the wastewater, producing a large amount of chromium-containing sludge, causing secondary environmental pollution, and chromium resources cannot be recycled.
The reprocessing of chromium-containing sludge requires steps such as acid leaching, chromium separation and flocculation. The process is complex and costly, and it is difficult for enterprises to adopt

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] In 10 liters of reaction tanks with mechanical stirring, add 5 liters of wastewater containing 100 mg / liter of chromium from Tannery A factory, adjust the pH value of chromium-containing wastewater to 8 with lime water, and add 0.05 grams of magnetic tetrachloride with a diameter of 5 nanometers. Ferric oxide particles, under 300 rev / min mechanical stirring conditions, add 0.05 gram of sodium citrate, react for 5 minutes;

[0030] The above-mentioned chromium-containing waste water is passed through a high-gradient magnetic separator to separate waste water containing 1 mg / liter of chromium and 1.1 grams of magnetic particle-chromium hydroxide complex. After the existing chemical flocculation and sedimentation treatment, the chromium content in waste water is less than 1.5 mg / liter, and the chromium content in sludge is less than 1 g / kg, meeting the national discharge standards;

[0031] The magnetic particle-chromium hydroxide complex is immersed in a 1 mole / liter sodi...

Embodiment 2

[0033] In a 10-liter reaction tank with mechanical stirring, add 5 liters of wastewater containing 800 mg / liter of chromium from the electroplating plant B, first add the reducing agent sodium sulfite, and then add lime water to adjust the pH value of the chromium-containing wastewater to 4 to convert the chromium For the precipitation of chromium hydroxide colloid, add 40 grams of magnetic ferric oxide particles with a diameter of 10 microns, and add 40 grams of diethylamine under 300 rpm mechanical stirring condition, and react for 60 minutes;

[0034] The above-mentioned chromium-containing waste water is passed through a magnetic drum separator to separate waste water containing 4 mg / liter of chromium and 50 grams of magnetic particle-chromium hydroxide complex. The mg / L primary chromium removal wastewater is treated according to this patent method for secondary chromium removal, and then treated according to the existing chemical flocculation sedimentation. The chromium co...

Embodiment 3

[0037] In a 10-liter reaction tank with mechanical stirring, add 5 liters of wastewater containing 300 mg / liter of chromium from Metallurgical Plant C, adjust the pH value of the chromium-containing wastewater to 11 with lime water, and add 3 grams of magnetic iron particles with a diameter of 1 micron , under the condition of mechanical stirring at 300 rpm, add 3 grams of oxalic acid and acetic acid ratio of 1:1 mixture, react for 30 minutes;

[0038] The above-mentioned chromium-containing waste water is passed through a magnetic drum separator to separate waste water containing 1.5 mg / liter of chromium and 8 grams of magnetic particle-chromium hydroxide complex. The chromium removal rate of the chromium-containing waste water reaches 99.5%. After the existing chemical flocculation and sedimentation treatment, the chromium content in waste water is less than 1.5 mg / L, and the chromium content in sludge is less than 1 g / kg, meeting the national discharge standards;

[0039] T...

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Abstract

The invention discloses a chromium-containing waste water treating and chromium recycling method, and belongs to the field of waste water treatment and comprehensive utilization. The method includes the steps: adjusting chromium-containing waste water oxidation-reduction conditions and a pH (potential of hydrogen) value to be 4-11, and enabling chromium to transform into a chromium hydroxide colloid to precipitate; adding inorganic magnetic particles and organic binding agents according to the proportion of 1/10-10 times of the weight of chromium in chromium-containing waste water; sufficiently stirring and mixing mixture, and separating the mixture by a magnetic separation device to obtain magnetic particle-chromium hydroxide compounds and chromium-free or low-chromium-containing common waste water; soaking the magnetic particle-chromium hydroxide compounds into strong-alkali aqueous solution to dissolve out chromium ions, and performing magnetic separation to obtain magnetic particles and chromium salt solution; enabling the magnetic particles to be recycled, and crystallizing the chromium salt solution to obtain chromium salt products. According to the method, chromium can be directly extracted and separated from the chromium-containing waste water, the chromium-containing waste water is changed into chromium-free or low-chromium-containing common waste water, the waste water generated in subsequent chemical flocculation and precipitation treatment and chromium content in sludge can reach national emission standards, and chromium resources can further be recycled.

Description

Technical field: [0001] The invention relates to a method for treating chromium-containing wastewater and recovering chromium, which is mainly used in the fields of tanning, electroplating, metallurgy, environmental treatment and the like. technical background [0002] Industries such as tanning, electroplating and metallurgy discharge a large amount of chromium-containing wastewater and chromium-containing sludge, causing serious waste of resources and environmental pollution. Technical solutions for chromium resource recovery and chromium pollution control are urgently needed. [0003] Traditional methods for treating chromium-containing wastewater include solvent extraction, ion exchange and adsorption, membrane separation, and biological methods. These methods are aimed at the treatment of chromium ions in wastewater, requiring the wastewater environment to be acidic. Due to problems such as treatment efficiency and cost , it is difficult to apply industrially. [0004]...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C02F9/12C02F101/22
CPCC02F1/488C02F1/54C02F1/66C02F1/70C02F9/00C02F2101/22
Inventor 官月平郭晨王浩杜蛟李涛
Owner UNIV OF SCI & TECH BEIJING
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