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Treatment method of chromium-containing wastewater

A treatment method and technology for chromium wastewater, applied in water/sewage treatment, water/sludge/sewage treatment, sludge treatment, etc., can solve problems such as increasing the output of chromium-containing precipitation and increasing treatment costs.

Active Publication Date: 2022-02-08
NORTHEAST NORMAL UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The addition of dehydrating agents further increases the yield of chromium-containing precipitates and increases the cost of treatment

Method used

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  • Treatment method of chromium-containing wastewater
  • Treatment method of chromium-containing wastewater
  • Treatment method of chromium-containing wastewater

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Experimental program
Comparison scheme
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Embodiment 1

[0029] The application provides a method for obtaining high-purity chromate from chromium-containing wastewater, the method comprising:

[0030] 1. Pretreatment of chromium-containing wastewater

[0031] (1) Take acidic chromium (Cr)-containing wastewater, wherein the concentration of Cr(VI) is 15-240 mg / L, and the pH of the wastewater is between -0.5-3.

[0032] (2) Add iron salt in waste water, the dosage of iron salt is to add between 8-20 according to the mol ratio of Fe / Cr, wherein the ratio of ferrous iron and ferric iron is 5-12 in iron salt, and iron salt includes But not limited to iron salts containing chloride ions or sulfate ions.

[0033] (3) Use liquid caustic soda to adjust the pH to 8-9, and the stirring speed is 100-150rpm for 1 hour, and then after standing still for 4 hours, iron and chromium precipitates are formed at the bottom, and the precipitates are collected into the concentration pool.

[0034] (4) Infuse air into the concentration tank with an aer...

Embodiment 2

[0068] Example 2 High-efficiency precipitation of iron and chromium in cold rolling workshop flushing wastewater

[0069] (1) The pH of cold rolling wastewater is 2.8, and the concentration of Cr(VI) is 41.2mg / L; add ferric chloride to the wastewater, and the dosage is Fe / Cr ratio 19.5; use liquid caustic soda to adjust the pH to 9, start stirring, The speed is 120rpm, after 1 hour of standing still for 4 hours, the bottom sediment is collected; the bottom sediment is aerated with air, the aeration rate is 0.5L / min L, after 1 hour of standing, after 24 hours of standing, the collected sediment is put into the dehydration tank.

[0070] (2) The resulting supernatant was collected, and the iron content was 490 mg / L. The pH was adjusted to 0.5 with nitric acid.

[0071] (3) sodium nitrate is added in the solution, and the addition is measured according to the mol ratio of nitrate and iron as 1.5;

[0072] (4) Add acetone to the solution, and the dose is measured according to th...

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Abstract

The application discloses a treatment method for chromium-containing wastewater, including: pretreatment: adding iron salt to the wastewater according to the molar ratio of iron and chromium being 8-20, and then using liquid caustic soda to adjust the pH to 8-9 for continuous stirring And after standing still, the bottom produces the first iron and chromium precipitate; Acetone is added to the supernatant, and after continuous stirring, the second supernatant is obtained, and the second supernatant is transferred to the reaction tank; the treatment of precipitation: when the molar ratio of acetone to nitrate is 0.06-0.18, start The reaction tank is heated up to 160-280°C, kept at a constant temperature for 2-4h, and then cooled to 90°C; then, 25-30% nitric acid is added to the reaction tank at a dosage of 0.02-0.05% of the volume of the reaction tank, and kept at a constant temperature for 5-8h , naturally cooled to room temperature, iron-containing precipitates were produced at the bottom, and the third supernatant was obtained. After enrichment in this application, the chromium concentration in the solution can be increased by 30-220 times, and at the same time, the iron is separated from the chromium as a precipitate.

Description

technical field [0001] The present application relates to the technical field of sewage treatment, in particular to a treatment method for chromium-containing wastewater. Background technique [0002] Chromium-containing wastewater is widely produced in electroplating, electrophoresis, tanning and steel processing industries. It is a toxic and heavy metal-containing wastewater that needs to be strictly disposed of in accordance with national standards. Conventional disposal methods for chromium-containing wastewater include the following: [0003] (1) Use ion exchange resin to fix hexavalent chromium ions on the resin surface through anion exchange; (2) Use membrane technology to concentrate chromium-containing wastewater. The use of ion exchange and membrane technology usually requires relatively clean chromium-containing wastewater, and the special requirements for water quality limit its widespread use. [0004] In some reported methods, chromium-containing solutions ar...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C02F1/52C02F11/127C02F101/22
CPCC02F1/5236C02F11/127C02F2101/22
Inventor 朱遂一林雪曲展苏婷霍旸边睿刘剑聪罗振
Owner NORTHEAST NORMAL UNIVERSITY