| Steel slag is the waste from the steelmaking process. Each year several million tons of discarded steel slag not only takes up a lot of land, but also will cause some pollution on the environment if not handled properly. At present, the utilization rate of steel slag is only about 60 percent in our country. How to make full use of steel slag becomes an important subject in environmental science field.Chromium-containing wastewater is mainly from electroplating, metallurgy, leather, printing and other industries, and cause serious environmental pollution. Cr (â…¥) in the Chromium-containing waste water is strong toxic, and has carcinogenic effect on human body. There are quite a few treatment methods of Chromium-containing wastewater, but the traditional methods are relatively high cost. Development of efficient, low-cost and new treatment methods become a hot spot in present study. Steel slag which is extensive and low price has a certain treatment capacity for Cr (â…¥), and can achieve the purpose of waste control by waste itself.This paper studies the removal of Cr (â…¥) in wastewater with steel slag, which is mainly divided into three parts:Part I: Batch experimental study. First is the kinetic experiment. It shows that steel slag has better removal efficiency on the Cr (â…¥), which can be described by Mckay 2 response model. Next is about the influence of dosage of steel slag, particle size of steel slag, temperature and raw water pH on removal effects. The results show that pH has little effect on the removal, while slag dosage, particle size and temperature have great influence.Part II: Column experimental study. Through chromatography column experimental studies simulating on-site wastewater treatment, the results show that steel slag with mass of 1.562kg and particle less than size of 80 mesh, handle a total of 105L wastewater with 20mg / L Cr (â…¥), and the solution concentration is all less than 0.5mg / L, which achieves significant results with potential applications. But due to the impact of basic oxides in the steel slag, within a specified time, there is a problem of effluent pH over 9.0 (according to "Integrated Wastewater Discharge Standard", pH should be from 6 to 9). So it is need to carry on neutralizing treatment on effluent.Part III: Study on removal mechanism. This part studies the removal mechanism of Cr (â…¥) from two aspects: the adsorption isotherms and morphological analysis experimental research. The results show that steel slag doesn't absorb Cr (â…¥) directly but first restore the Cr (â…¥) to Cr (â…¢). Some of Cr (â…¢) is adsorbed on the surface of steel slag. Some of Cr (â…¢) forms precipitation. Lastly, Some of Cr (â…¥) and Cr (â…¢) were combined on the form of chemical bond by hydrated oxides of iron and manganese in steel slag and wrapped to inside of steel slag.
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