Hexavalent chromium wastewater treatment method.
Hexavalent chromium wastewater is mainly used in electroplating, metallurgy, tanning, chemical and other industrial wastewater, which contains a large number of hexavalent chromium ions, which has a serious impact on the environment and human health. Therefore, the treatment of hexavalent chromium wastewater is crucial. In this paper, we will introduce several common hexavalent chromium wastewater treatment methods, including chemical reduction method, ion exchange method, membrane separation method, biological treatment method, etc., and analyze their advantages and disadvantages, in order to provide reference for hexavalent chromium wastewater treatment.
Chemical reduction method.
Chemical reduction is one of the most widely used methods for treating hexavalent chromium wastewater. This method uses a reducing agent to reduce non-precipitable hexavalent chromium to precipitable trivalent chromium, and then removes it by neutralization, flocculation, precipitation, filtration, etc. Commonly used reducing agents include ferrous sulfate, sodium sulfite, etc. The chemical reduction method has the advantages of simple operation and good treatment effect, but it has the problems of large consumption of reducing agent and easy secondary pollution.
The reaction formula for the reduction of hexavalent chromium by sodium sulfite is as follows:
CR2(SO4)3DEC3(NH4)2S2O8DECA8H2O=2H2CRO4DEC3(NH4)2SO4DECA6H2SO4
The reaction formula for the reduction of hexavalent chromium by ferrous sulfate is as follows:
cr2o7 2- +6fe2+ +14h+ ==2cr3+ +6fe3+ +7h2o
Integrated approach.
Due to the limitations of single treatment methods, in recent years, the integrated treatment method has gradually become a research hotspot in the treatment of hexavalent chromium wastewater. The integrated treatment method combines multiple treatment methods to achieve better treatment results. For example, hexavalent chromium can be reduced to trivalent chromium by chemical reduction, which can then be further removed by ion exchange or membrane separation. Alternatively, biological treatment can be used to pre-treat the wastewater to reduce the concentration of hexavalent chromium and then use other methods for advanced treatment.
Conclusion. Hexavalent chromium wastewater treatment is a challenging task, which requires comprehensive consideration of the efficacy, cost, environmental friendliness and other factors of the treatment method. Methods such as chemical reduction, ion exchange, membrane separation, and biological treatment have their own advantages and disadvantages, and the appropriate method should be selected according to the actual situation. At the same time, with the continuous progress of science and technology, more efficient and environmentally friendly hexavalent chromium wastewater treatment methods will be developed in the future, which will provide strong support for solving the problem of hexavalent chromium wastewater pollution.
In conclusion, hexavalent chromium wastewater treatment is a necessary means to protect the environment and human health. In practical application, the appropriate treatment method should be selected according to the characteristics of wastewater, treatment requirements and economic conditions and other factors to ensure that the wastewater is discharged up to standard and achieve sustainable development.