Zero-discharge treating process for coking wastewater of iron and steel plant

Abstract

The invention belongs to the field of water supply and discharge in the iron and steel industry, and in particular relates to a zero-discharge treating process for coking wastewater of an iron and steel plant. The process comprises two stages of treatment on the coking wastewater according to a conventional method, and is characterized in that: conventional biochemically treated effluent is collected, is led into a subsurface constructed wetland, is subjected to advanced treatment, and is used for make-up water for a drain slag circulating system of a blast furnace. The advanced treatment is to plant domesticated canna, cyperus alternifolius and other plants with developed roots so as to effectively remove polycyclic aromatic compounds and phenol cyanogen compounds which are hard to be biodegraded in the coking wastewater by using comprehensive adsorption and degradation effect of plants, soil and microbes, and effectively improve the quality of the coking wastewater. The process saves investment, is convenient for implementation, has clear treatment effect, is applicable to coking wastewater treatment process for domestic iron and steel enterprises, and realizes zero discharge of the coking wastewater.

Description

technical field [0001] The invention belongs to the field of water supply and drainage in the iron and steel industry, and in particular relates to a zero-discharge treatment process for coking wastewater in iron and steel plants. technical background [0002] A large amount of coke is required to reduce iron oxide to iron metal during the blast furnace ironmaking process in steel plants. Coke also acts as a fuel. Provides a skeletal effect to allow gases to pass freely through the blast furnace bed. The process of coke production will produce a large amount of coking wastewater. Coking wastewater is the wastewater formed during the high-temperature carbonization process of coal, gas purification, and chemical product refining. Coking wastewater contains phenol, ammonia nitrogen, oxygen, benzene, pyridine, indole and Dozens of pollutants such as quinoline have complex components, high pollutant concentration, low chroma, high toxicity, and very stable properties. Some of t...

AI Technical Summary

Problems solved by technology

After coking wastewater undergoes the above-mentioned pretreatment and conventional biochemical two-stage treatment, it is still difficult to meet the standards for phenol, cyanide, COD and ammonia nitrogen in the effluent, especially the two indicators of COD and ammonia nitrogen seriously exceed the standard, and due to the high content of organic matter and complex components, It is also not suitable for advanced treatment using membrane technology, and it is even less likely to achieve zero emissions

At present, most coking wastewater in China is directly discharged after the above two-stage treatment, which causes great harm to the surrounding environment.

Images