With the development of petrochemical process, people gradually realize that some production processes do not require high water quality, and the sewage generated in other processes can be mixed with fresh water in a certain ratio as the influent of these processes.

Then, with the advancement of water treatment technology, it has been found that some process drainage water is complicated and difficult to handle, while other processes have simple drainage water quality, and it is more economical to treat the sewage separately according to different water quality.

Petrochemical enterprises are large water users, and a considerable part of China's petrochemical enterprises are located in drought or water shortage areas. Insufficient water supply has become one of the restrictive factors for petrochemical enterprises to expand production.

On the other hand, China's economy has developed rapidly and oil consumption has continued to rise. The production scale of domestic petrochemical enterprises has continued to expand and the processing depth has been continuously improved. The quality of petrochemical wastewater has shown a trend of increasing types of pollutants and complex water quality. With the increasing tension of water resources and the increasing awareness of environmental protection, the treatment of petrochemical wastewater has attracted more and more attention.

Petrochemical industry is a series of organic matter processing processes based on petroleum as raw materials and processes such as cracking, refining, fractionation, reforming and synthesis. Petrochemical products have long production processes, many production facilities, and a large amount of sewage. The typical petrochemical wastewater contains petroleum, CODCr, ammonia nitrogen, sulfur, phenol, cyanide and other conventional pollutants. At the same time, different enterprises have different kinds of characteristic pollutants related to their organic chemical products, such as polycyclic aromatic hydrocarbon compounds, aromatic amine compounds, heterocyclic compounds, etc., due to different products. And there are many toxic substances. In addition, fluctuations in production such as opening, maintenance, and changes in raw material sources can cause changes in the amount of sewage and the content and nature of pollutants, and increase the impact load on wastewater treatment facilities.

In recent years, water resources have become increasingly tight, and researchers have treated some wastewaters appropriately/deeply as direct water for other processes. According to reports, in the whole process, the amount of water is about 20 to 50 times that of crude oil processing. Although most of the water can be recycled, it still produces 0.4 to 1.6 times the crude oil processing volume.

The country pays more and more attention to environmental governance, the improvement of environmental protection standards and the gradual implementation of supervision and strictness, making it increasingly difficult for polluting enterprises to evade environmental governance responsibilities, the potential demand left by a large number of environmental history debts, and the start of new projects. The new water treatment demand and the expansion and expansion of existing energy and chemical projects under the higher environmental governance standards have provided the source of power for the continuous growth of the energy and chemical wastewater treatment industry.