At present, sewage treatment generally adopts traditional sewage treatment processes, using flocculation sedimentation and sand filtration systems. It is designed to add ferric chloride to the distribution well of the sedimentation tank of the A2/O system to enhance biological phosphorus removal and reduce the phosphorus concentration in the effluent of the sedimentation tank. The effluent after precipitation is sent to the sand filter through the lifting pump station, and the sand filter is backwashed with air and water. The filtered water will be sent to the clean water tank, pressurized, and then enter the reuse water pipe network. Such as Dengjiacun Sewage Treatment Plant in Xi'an, Beishiqiao Sewage Purification Center in Xi'an, Textile City Sewage Treatment Plant in Xi'an, and Dianzi Village Sewage Treatment Plant in Xi'an.

In the traditional sewage treatment system, the sedimentation tank is used for the coagulation and sedimentation of sewage, which cannot form good particle agglomeration conditions and cannot produce flocs, which makes the solid-liquid separation efficiency very low.

Problems in sewage treatment:

(1) Shortage of funds for construction of sewage treatment plants:

Although more than 100 sewage treatment plants have been built in our country, they are far from meeting the needs of urban industrial and agricultural production and people's lives. This is reflected in the low treatment rate in a certain city, that is, insufficient sewage treatment capacity, and also in the planning of sewage treatment plants in large cities. On construction planning. However, in small and medium cities, especially in the northwest, the planning and construction of sewage treatment have not been included in the urban development agenda. One of the main reasons is that there is no special construction funds, and water pollution in some areas is getting more and more serious. If we wait for capital investment to build sewage treatment plants, the environment will tend to deteriorate, causing inconvenience to people's lives and harming people's physical and mental health. Therefore, we should raise funds from various channels to speed up the treatment of water pollution and leave a beautiful living environment for future generations.