With the development of pharmaceutical, chemical, dye and other industries, there are more and more refractory wastewaters with high concentration. At the same time, with the improvement of living standards, environmental awareness is enhanced, and the more people migrate and change the refractory organic substances in the environment. The more concerned, however, the treatment of high concentration of refractory organic matter is a difficult point in wastewater treatment, and it is difficult to treat it by conventional processes (such as coagulation and biochemical methods) because:

1. The concentration of such wastewater is high, CODCR is generally tens of thousands of mg / L, and even as high as more than 100,000 mg / L;

2. The pollutants contained therein are mainly aromatic compounds, and the BOD/COD is very low, generally below 0.2, which is difficult to biodegrade;

3, is the toxicity of pollutants, many substances are listed in the new list of environmental pollution, such as aniline, nitro stupid;

4, the content of inorganic salts is high, reaching tens of thousands or even more than 100,000.