Treatment method for analyzing waste liquid

Abstract

The invention discloses a treatment method for analyzing a waste liquid. The waste liquid contains Cr<6+>, Cr<3+> and Fe<3+>; the method comprises the following steps: (I) adding a pH regulator into the waste liquid to adjust the pH value of the waste liquid to 2-4, and adding a reducing agent to convert Cr<6+> into Cr<3+>; (II) adding a pH regulator to adjust the pH value of the solution after the reducing reaction to 10-12 so that the Fe<3+> in the solution is converted into Fe(OH)3 and subjected to coagulating precipitation for separation; and (III) adding a pH regulator to adjust the pH value of the solution after the precipitation to 6-9 so that the Cr<3+> in the solution is converted into Cr(OH)3 and precipitated and separated out. The treatment method for analyzing waste liquid disclosed by the invention effectively separates heavy metals in the waste liquid.

Description

technical field [0001] The invention relates to a treatment method for analyzing waste liquid, in particular to a Cr-containing 6+ 、Cr 3+ , Fe 3+ The waste liquid treatment method is especially suitable for the waste liquid produced by the potassium dichromate method for COD analysis. Background technique [0002] Laboratory analysis and testing often produce a large amount of waste liquid, such as the determination of chemical oxygen demand (Chemical Oxygen Demand, COD) by potassium dichromate method, the determination of iron in iron ore by potassium dichromate method, and the determination of iron in soil by potassium dichromate method. Analytical waste liquid generated from organic matter, etc., containing Cr 6+ 、Cr 3+ , Fe 3+ If the plasma waste liquid is discharged directly, it will not only cause environmental pollution, but also cause a great waste of resources. [0003] COD is a comprehensive and important indicator for evaluating the degree of organic polluti...

AI Technical Summary

Problems solved by technology

[0019] Because the components in the analysis waste liquid are complex and the single treatment method is not thorough, it is difficult to treat the waste liquid safely and harmlessly.

Firstly due to Cr(OH) 3 It can be dissolved in strong alkali solution, so when adding alkali to precipitate Cr 3+ , Fe 3+ , Hg 2+ When the pH value is difficult to control, when the pH is low, Fe 3+ , Hg 2+ The precipitation is not complete, and when the pH is high, Cr(OH) 3 Cr in effluent due to dissolution 3+ , which can be re-oxidized to Cr in an oxidizing environment 6+ , resulting in incomplete detoxification; the useful components in the waste liquid should not be separated, resulting in a waste of resources; the waste liquid also contains residual organic pollutants that are not suitable for degradation, and it is difficult to remove them by precipitation, reduction and other treatment methods; secondly, there are The heavy metal ions contained in the produced precipitate or waste residue are easily dissolved to cause secondary pollution

In addition, the investment cost of processing, operating cost, and the difficulty of operation and management are all important factors to be considered.

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