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Chromium containing waste water treatment method

A treatment method and technology for chromium wastewater, applied in water/sewage treatment, water/sewage multi-stage treatment, water/sludge/sewage treatment, etc. more questions

Inactive Publication Date: 2004-12-22
DONGFENG MOTOR FASTENER CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0010] The purpose of the invention is to solve the following problems in the existing chromium-containing wastewater treatment method: when hexavalent chromium is reduced to trivalent chromium, the pH value of the chromium-containing wastewater must be adjusted to 2-3 with acid; The trivalent chromium completely forms the precipitation of chromium hydroxide, but part of it is discharged in the form of trivalent chromium ions; the dosage of solid ferrous sulfate is large, and the precipitation of ferric hydroxide is more

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  • Chromium containing waste water treatment method
  • Chromium containing waste water treatment method
  • Chromium containing waste water treatment method

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Embodiment 1

[0014] Embodiment 1: the treatment method of chromium-containing wastewater is: 1. newly prepare liquid ferrous sulfate by displacement reaction for subsequent use, the concentration of liquid ferrous sulfate is 38~40%, and the pH value is 4; Regulate water quality and remove oil; ③ add newly prepared liquid ferrous sulfate to the reaction tank to reduce hexavalent chromium in chromium-containing wastewater to trivalent chromium, and press Cr 6+ with Fe 2+ Pour into liquid ferrous sulfate with a molar ratio of 1:6-9; ④Add sodium hydroxide to the neutralization tank to completely form trivalent chromium into chromium hydroxide precipitation, wherein the concentration of sodium hydroxide is 220-260g / l ; ⑤ After entering the sedimentation tank for sedimentation and separation, the wastewater is discharged, and the sludge is treated centrally after passing through the filter press.

Embodiment 2

[0015] Embodiment 2: According to figure 1 As shown in the process flow chart, the treatment method of chromium-containing wastewater is as follows: ① freshly prepare liquid ferrous sulfate by replacement reaction, the concentration of liquid ferrous sulfate is 38-40%, and the pH value is 4; ② for chromium-containing wastewater Adjust the water quality and remove the oil quality through the oil separation adjustment tank; ③Add the newly prepared liquid ferrous sulfate in the reduction reaction tank to reduce the hexavalent chromium in the chromium-containing wastewater to trivalent chromium, and press Cr 6+ with Fe 2+ Pour into liquid ferrous sulfate with a molar ratio of 1:7-8; ④Add sodium hydroxide to the neutralization reaction tank to completely form trivalent chromium into a precipitate of chromium hydroxide, wherein the concentration of sodium hydroxide is 220-260g / l; ⑤After entering the inclined plate sedimentation tank for sedimentation and separation, the waste wate...

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Abstract

A process for treating the Cr-contained sewage includes preparing liquid-state ferrous sulfate by displacement reaction, removing oil from said sewage, adding said liquid-state ferrous sulfate, reduction reacting to reducing 6-valence Cr to 3-valence Cr, adding alkali to generate deposit of chromium hydroxide, deposit separation, discharging water, and press filter of mud.

Description

technical field [0001] The invention relates to a wastewater treatment method, in particular to a chromium-containing wastewater treatment method. Background technique [0002] The cleaning wastewater after galvanizing low-chromium passivation is collected separately because it contains highly toxic hexavalent chromium, which is called chromium-containing wastewater. The PH value of chromium-containing wastewater is above 4, and its main components are chromic anhydride, sulfuric acid and nitric acid, and the ions contained include Cr 6+ , Fe 2+ , Zn 2+ 、Cr 3+ 、Na + , NO 3 - , SO 4 2- etc., the ions that need to be processed are Cr 6+ , Fe 2+ , Zn 2+ 、Cr 3+ , where Cr 6+ It is the main ion to be processed, and its concentration is around 20mg / l. In the presence of acid, chromic anhydride in solution exists as: [0003] <chemistry num="001"> <chem file="200410012654_cml001.xml" / > < / chemistry> [0004] When acid is added to the solution, t...

Claims

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Application Information

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IPC IPC(8): C02F1/58C02F9/02C02F9/04
Inventor 戴之伦孔娜
Owner DONGFENG MOTOR FASTENER CO LTD
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