Method for removing fluoride from wastewater

Abstract

The invention discloses a method for removing fluoride from wastewater. The method comprises pre-treatment, internal electrolysis reaction, precipitation reaction and coagulation reaction. The combination of calcium hydroxide and OH<-> which is produced in the internal electrolysis reaction in aluminium and copper bimetal is adopted for increasing the pH value. The addition of calcium hydroxide is greatly reduced, and compared with a conventional calcium salt precipitation method, the method overcomes the problem that a CaF2 precipitate coats the surfaces of Ca(OH)2 particles. Compared with a conventional fluoride removal method of aluminium salt complexation and calcium salt coagulation, the method adopts humic acid which widely exists in nature and is low in price as an adsorbent and a flocculant. Aluminum fluoride complex ions in wastewater can be adsorbed, and the addition of Ca(OH)2 is reduced. The effect of fluoride removal is improved, and the cost of fluoride removal is reduced. Aluminum ions can be effectively removed from the wastewater, so that the residue of aluminum in the processed outlet water is greatly decreased, and secondary pollution is prevented from generation. The method is simple in control parameters, mild in condition, and easy to apply, and is suitable for massive industrial production.

Description

technical field [0001] The invention belongs to the technical field of water treatment, and in particular relates to a method for removing fluoride in waste water. Background technique [0002] Industrial fluorine-containing wastewater comes from fluorine-containing ore mining, coke, glass, fertilizer, electroplating, electronics, solar cell production and other industries. The composition of industrial fluorine-containing wastewater is complex, and the concentration covers a wide range, from tens of milligrams per liter to thousands, or even tens of thousands. Taking the generation of fluorine-containing wastewater in the crystalline silicon solar cell industry as an example, in the production process of crystalline silicon solar cells, hydrofluoric acid is used to corrode, texture and wash the surface of crystalline silicon, resulting in the generation of high fluorine acidic wastewater. Due to the different concentrations of wastewater produced in different production st...

AI Technical Summary

Problems solved by technology

But the disadvantage of this method is that the Ca(OH) in the solution 2 CaF 2 Precipitation wrapped, unable to allow it to fully react with the solution, resulting in a large amount of lime and calcium salts

Even so, the effect of fluorine removal is still poor, and it also increases the cost of chemicals and generates a large amount of sludge; the aluminum salt coagulation and sedimentation process generally needs to increase the dosage to improve the removal rate of fluorine, which will increase the treatment cost. At the same time, the treated water contains a large amount of aluminum ions and causes secondary pollution

In addition, traditional high molecular polymers cannot effectively flocculate and remove the complexed fluoride formed during the treatment process, resulting in a high content of fluoride in the treated effluent, making it difficult to discharge in a stable manner

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