Method for treating acid-washing wastewater and metallic ions in iron and steel industry

Abstract

The invention provides a method for treating acid-washing wastewater and metallic ions in iron and steel industry, which comprises steps as follows: acid-washing wastewater naturally flows into a water collecting well and enters a preneutralization filter chamber under the elevation action of a pump, the preneutralization filter chamber is provided with 10-200mm limestone which is in a graded distribution mode, and after the acid-washing wastewater is preneutralized by the limestone, the pH value of the effluent water is controlled at 5-6, wherein the method provided by the invention greatly lowers the chemical expenses and operating cost as compared with the conventional method of directly adding an alkali solution; the acid-washing wastewater, which is subjected to initial pH value regulation, naturally flows into an oil separation regulating chamber, so that iron ions in the wastewater react with the alkali solution to form a precipitation mixture of ferric hydroxide, zinc hydroxide and the like; and the wastewater is elevated into a membrane solid-liquid separator to complete solid-liquid separation, so that the wastewater can be discharged after reaching the standard. The invention thoroughly solves the problems that the precipitate can not easily settle, the iron can not be easily removed, and the iron ions are dissolved out. The invention has the advantages of simple technique, high economy, low requirements for technical levels of workers, and high controllability, is reliable to operate, and has wide market prospects.

Description

technical field [0001] The invention belongs to the technical field of environmental protection wastewater treatment, and relates to a treatment method for industrial wastewater, in particular to a treatment method for pickling wastewater and heavy metal ions in the iron and steel industry. Background technique [0002] Before surface electroplating and spraying, steel component blanks are generally pickled to remove oxides on the surface, thus generating pickling wastewater. In the pickling wastewater of different production processes, the pH value is low, it is strongly acidic, and contains different concentrations of ferrous ions, zinc ions, copper ions or nickel ions. The main treatment method for this kind of pickling wastewater in the iron and steel industry is the traditional aeration neutralization precipitation method. Generally, aeration is used to oxidize ferrous ions into iron ions, and then the iron ions in the wastewater are precipitated by adding lye. After P...

AI Technical Summary

Problems solved by technology

[0003] (1) The process route is lengthy and occupies a large area;

[0004] (2) The traditional process requires high reaction conditions and poor impact resistance. When the pretreated raw water volume, water quality and reaction conditions fluctuate greatly, the quality of the effluent is unstable, and the effect is difficult to guarantee

[0005] (3) It is necessary to add flocculants and coagulants, and the unit operating cost of wastewater is high, which is likely to cause secondary pollution;

[0006] (4) The process system of the chemical precipitation method is complex, requires high technical level of workers, labor intensity is high, and operation control is difficult;

[0007] (5) When the wastewater contains a high concentration of iron ions, it is not easy to settle in the sedimentation tank, resulting in a large amount of sludge and a high moisture content of the sludge

In addition, the sedimentation mixture stays in the sedimentation tank for a long time, and iron ion inversion phenomenon will occur, which will cause the COD (chemical oxygen demand) index in the effluent to exceed the standard, causing secondary pollution

It is precisely because of the above reasons that the development of traditional crafts and the application in practical engineering are limited.

Images