Method and system for treating leather retanning low-chromium wastewater through microelectroanalysis

Abstract

The invention discloses a method and a system for treating leather retanning low-chromium wastewater through microelectroanalysis. The method comprises the following steps of (1) aerating retanning dyeing wastewater in a microelectroanalysis filler reaction bed, wherein the gas water ratio is 15:1 to 20:1, the wastewater and a microelectroanalysis filler in the microelectroanalysis filler reaction bed are subjected to oxidation reaction, and the retention time is 4 to 6 hours; (2) adjusting the pH value to 8.0 to 10.0 in a pH adjusting tank; (3) discharging the wastewater into a flocculation tank to be subjected to flocculation reaction to generate Cr(OH)3; (4) after flocculation reaction, discharging the wastewater into a settling tank to be subjected to settling, wherein separation between mud and water is realized, and the Cr(OH)3 is removed. The system comprises the microelectroanalysis filler reaction bed, the pH adjusting tank, the flocculation tank, the settling tank and a controller, wherein the microelectroanalysis filler reaction bed, the pH adjusting tank, the flocculation tank and the settling tank are sequentially connected. According to the method and the system, chrome ions can be fully formed into Cr(OH)3 precipitate to be separated out; due to the adoption of a compound iron and carbon microelectroanalysis filler, the defects that an iron and carbon is easily dissolved, blocked and agglomerated are overcome, and the stability is improved.

Description

technical field [0001] The invention relates to an iron-carbon micro-electrolysis reaction method for treating leather-making retanning and dyeing low-chromium wastewater and a system for realizing the method, belonging to the technical field of sewage treatment. Background technique [0002] Chrome tanning wastewater is mainly divided into main tanning wastewater and retanning dyeing wastewater. The main tanning wastewater contains high chromium concentration (3000-4000mg / L), and it is generally reused; retanning dyeing wastewater has a low chromium concentration (150 ~1000mg / L), it is not used for reuse but is generally treated and then comprehensively treated together with other wastewater. The wastewater is acidic, with a pH value of about 3.8 to 4.0. [0003] There are currently technical difficulties in the treatment of retanning and dyeing wastewater. The total chromium concentration still cannot reach 1.5mg / L after conventional alkali-adding precipitation and other ...

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Problems solved by technology

[0003] There are currently technical difficulties in the treatment of retanning and dyeing wastewater. The total chromium concentration still cannot reach 1.5mg / L after conventional alkali-adding precipitation and other processes. The treated wastewater is mixed with other wastewater before treatment, and the chromium ions are transferred to the remaining sludge. , the chromium content in the sludge may seriously exceed the standard, which will affect the similar treatment of the sludge and even cause greater pollution; in addition, it is difficult to reduce the chroma of the wastewater, the main reason is that the components of the wastewater are complex, and the removal of Cr 3+ In addition, there are synthetic organic substances such as organic solvents, azo dyes and metal chromium dyes in the water. These refractory organic substances increase the difficulty of wastewater treatment, especially the chromium dyes are difficult to break down, making it difficult to remove chromium ions and chroma.

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