Abstract : This paper briefly introduces the sewage treatment process, the reasons for the waste of electricity during non-speed operation, and introduces two automatic control methods. Keywords : process introduction, automatic control, therapy 1 Introduction The pillar industries of the 21st century include information, electronics, environmental protection, energy conservation, and biotechnology. With the development of the national economy, various enterprises have emerged, cities have expanded, and the water consumption of newly built residents has increased. Therefore, the purification and treatment of industrial wastewater and domestic sewage has been raised to the agenda. To this end, three points should be achieved: (1) Wastewater and sewage discharge requirements should meet the standards to avoid pollution of the water sources of rivers, lakes, and seas; (2) Wastewater and sewage should be reused as much as possible after purification treatment; (3) Most cities in China are short of water, especially in the north and west, so "open source and reduce flow" and "saving water and electricity" are equally important and are fundamental issues related to the long-term sustainable development of the national economy. At present, most wastewater and sewage treatment in China adopts the aeration method, which is essentially microbial treatment. It has a wide range of applications, such as cotton spinning, wool spinning, hemp spinning, printing and dyeing, washing, medicine, food, light chemical industry, metallurgy, and oil refining industries. In short, wherever water is used, there will be sewage discharge. It must be treated to meet the standards before it can be discharged or recycled to avoid environmental pollution. Sewage treatment involves all walks of life, production and daily life, and has a wide range of impacts. It is a major issue that cannot be ignored. 2 Waste exists in aeration treatment (1) There are usually at least two aeration tanks, and the equipment capacity is configured according to the development of the enterprise. They are generally too large, and the actual usage is small. Therefore, the situation of "horse pulling a cart" is common, which wastes electricity; (2) Many units have excessive oxygen supply in aeration tanks and use manual methods to shut down the number of Roots blowers (or general blowers) in operation. This cannot be adjusted in a timely and effective manner, which wastes electricity; (3) The oxygen supply should be related to the drainage volume and the quality of sewage treatment, as well as the temperature changes in the four seasons and the temperature changes during the day and night. When automatic speed adjustment is not possible, there is a waste of electrical energy; (4) Excessive oxygen supply often affects the quality of sewage treatment, causing a reduction in microorganisms and a worsening of treatment effect, which also results in a waste of electrical energy; (5) Sewage discharge only needs to meet or slightly exceed the standard. Due to excessive oxygen supply during aeration, it is also uneconomical and results in a waste of electrical energy. Therefore, it is urgent to require automatic control according to the set parameters; [b][align=center]For details, please click: Application of frequency converters in sewage aeration tanks[/align][/b]