Method and device for split pole continuous flow type electrochemical treatment of chromium-containing wastewater

Abstract

The invention provides a novel method and a novel device for electrochemical treatment of chromium-containing wastewater. A cathode chamber 1 and an anode chamber 2 are separated from each other by a salt bridge 3 containing NaCl, and an anode plate 5 consists of a perforated iron plate and iron filings of 1-2cm in thickness. The chromium-containing wastewater enters the anode chamber from a position between the anode plate 5 and the salt bridge 3, the chromium is reduced into Cr<3+> ions by Fe<2+> ions released on the anode plate, and the Cr<3+> ions flow into a precipitation reaction chamber 6 along with water to mix with OH<-> ions from the cathode chamber 1 so as to generate Fe(OH)3 and Cr(OH)3 precipitates. Small pieces of flocs in the water enter an inclined tube precipitation chamber 7 for continuous precipitation and finally enter a clean water chamber 8. The method adopts a continuous water inflow mode to promote water flow, the anode chamber 2 is acidic due to oxidation-reduction reaction, the precipitation chamber 6 is alkalescent due the injection of cathode liquor, and the whole running process does not need additional acid and alkali.

Description

technical field [0001] The invention relates to the field of chromium-containing wastewater treatment. Background technique [0002] The electrochemical treatment technology of chromium-containing wastewater refers to the generation of reducing substances (Fe 2+ ) to hexavalent chromium (usually CrO 4 2- form) reduced to trivalent chromium (Cr 3+ ), and then by generating Cr(OH) 3 Precipitation removes chromium from wastewater. [0003] The anode used in this technology is usually Fe (or Fe / Al), and when energized, an oxidation reaction occurs on the anode to release Fe 2+ ion (or Fe 2+ 、Al 3+ ions); Fe 2+ Ions and CrO 4 2- The reaction produces Fe 3+ ions and Cr 3+ Ion; Fe 3+ Ions, Cr 3+ ion (or Al 3+ ions) and the OH produced on the cathode - Ions react to form Fe(OH) 3 , Cr(OH) 3 (or Al(OH) 3 ) precipitation, and finally through sedimentation or air flotation to separate mud and water to remove chromium from wastewater. [0004] In the prior art, the a...

AI Technical Summary

Problems solved by technology

Therefore, in the existing electrochemical treatment of chromium-containing wastewater, the pH value of the wastewater is adjusted to be acidic by adding acid in the reduction stage, and the pH value of the wastewater is adjusted to alkaline and neutral by adding alkali in the subsequent precipitation stage, which consumes a lot of acid and alkali. , and bring about related safety production issues

In addition, the addition of acid and alkali requires precise metering, and the treatment system must be equipped with corresponding metering pumps and sensors, resulting in increased equipment investment and maintenance costs

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