High-salt wastewater refers to wastewater with a total salt content of at least 1%. It mainly comes from chemical plants, oil and natural gas collection and processing, etc. This wastewater contains a variety of substances (including salt, oil, organic heavy metals and radioactive substances). Salt wastewater is produced in a wide range of ways, and the amount of water is increasing year by year. The environmental impact of removing organic pollutants in saline wastewater is crucial. Biological treatment is used, and high-concentration salts have an inhibitory effect on microorganisms. Physicochemical treatment requires large investment and high operating costs, and it is difficult to achieve the expected purification effect. The use of biological methods to treat such wastewater is still the focus of research at home and abroad.

  The types and chemical properties of organic matter in high-salt organic wastewater vary greatly depending on the production process, but most of the salts contained are Cl-, SO42-, Na+, Ca2+ and other salts. Although these ions are essential nutrients for the growth of microorganisms, they play an important role in promoting enzyme reactions, maintaining membrane balance and regulating osmotic pressure during the growth of microorganisms. However, if the concentration of these ions is too high, it will inhibit and poison the microorganisms. The main manifestations are: high salt concentration, high osmotic pressure, dehydration of microbial cells causing cell protoplasm separation; salting-out effect reduces the activity of dehydrogenase; Bacteria have toxic effects; high salt concentration increases the density of wastewater, and the activated sludge is easy to float and lose, which seriously affects the purification effect of the biological treatment system.