Method for treating acidic fluorine-containing waste water

Abstract

The invention relates to a method for treating acidic fluorine-containing waste water. The method comprises the following steps sequentially: (1) adding calcium-containing substance into the fluorine-containing waste water to be treated and adjusting the pH value of the waste water to be about 4.0 to 9.0; and (2) adding water-soluble gamma-polyglutamic acid serving as a biologic capturing agent into the mixture, fully stirring and standing the mixture, separating the supernatant and collecting the precipitated sludge after the mixture is precipitated and demixed, wherein the calcium-containing substance at least comprises one of calcium hydroxide, calcium oxide or calcium salt. The method overcomes the technical disadvantages in the prior art; the high molecular water-soluble gamma-polyglutamic acid with a molecular weight between 500,000 and 1,500,000 is used in the treatment of the acidic fluorine-containing waste water; and repeated experiments show that the fluorine removing effect is excellent and the treated waste water can meet the national first-class discharge standard; moreover, the method has the advantages of low treatment cost, high efficiency for the treatment process, environment friendliness and no secondary pollution.

Description

technical field [0001] The invention mainly relates to a method for treating acidic fluorine-containing wastewater, in particular to a method for applying biopolymer materials to treat fluorine-containing wastewater, and belongs to the field of industrial wastewater treatment. Background technique [0002] Fluorine is a gas at room temperature, its chemical properties are very active, and it can chemically react with many substances. It can form easily soluble metal complexes in acidic media, and mostly exists in the form of fluoride ions in alkaline media. Fluorine is widely distributed in nature in the form of various compounds. Fluorine is a trace element. Although adding a small amount of fluorine to drinking water is beneficial to the human body, it is an accumulative poison and has obvious toxicity to many organisms. It is easily absorbed by plants and humans and deposited in the body. Fluoride can interfere with the activity of various enzymes in the human body, inh...

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Problems solved by technology

[0017] Theoretically speaking, when these equations reach equilibrium at room temperature 25°C and pH = 7, the concentration of F ions should not be lower than 10 mg / L, but in practice, this level is far from being reached, so it is generally impossible to pass conventional calcium addition. The precipitation method reduces the fluorine content in the solution to below 10mg / L;

[0018] (2) In addition, the inventors found in practice that CaF 2 As soon as the precipitated particles are formed, they are wrapped in granular Ca(OH) 2 The surface, on the one hand inhibits the granular Ca(OH) 2 The continuous dissolution and dissociation, so that Ca(OH) 2 It cannot be fully utilized, so the amount of lime usually needs to be large, but it still cannot achieve good results, the fluoride removal rate is not high, and at the same time, it causes more sludge in the end;

[0019] (3) Adding chemical flocculant is to promote CaF 2 However, in fact, the settling speed of sludge sediment is very slow, and dehydration is also difficult. When dealing with large-flow discharge, the storage period is long, and it cannot adapt to continuous treatment and continuous discharge. In terms of time, the treatment efficiency is low.

[0020] (4) The commonly used chemical flocculant is polyacrylamide, and its decomposition product is neurotoxin, which is not only unfavorable to the operator, but also unfriendly to the environment, and the follow-up treatment is troublesome

However, γ-polyglutamic acid does not have the function of capturing negative fluoride ions. Therefore, those skilled in the art believe that adding γ-polyglutamic acid cannot solve the problem of excessive fluorine content in the discharge water.

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