Abstract: With the continuous expansion of industrial scale, wastewater pollution has become the world's leading ecological killer. Effective control of wastewater is now a top priority. This paper, starting with modern computer control, utilizes the powerful logic functions of PLC technology and combines sophisticated software and hardware to present an advanced wastewater treatment system solution. Keywords: Wastewater treatment, PLC , Control system I. Introduction In today's rapidly developing industrial world, water resources, the source of life, have been increasingly polluted. Traditional manual chemical treatment methods are far from meeting societal needs. Increased chemical dosage further degrades water quality. To address this, this paper designs a PLC-based control system solution that integrates data acquisition, data management, graphical display, status display, historical data recording, and alarm printing. It also achieves the organic unification of operator management, production process management, equipment management, and safety management, optimizing control methods, saving energy and chemical dosage, and significantly improving treatment efficiency. II. System Composition Diagram This solution adopts a comprehensive control method using a host monitoring computer and a lower-level PLC. The upper-level monitoring computer is responsible for communicating with the PLC, monitoring and operating the entire wastewater treatment process, and has functions such as data recording, fault alarm, and parameter setting. The lower-level PLC collects signals such as pH, ORP value, flow rate, liquid level signal, pump and valve operation status, and faults on site, and outputs control signals for various pumps and valves according to the pre-programmed control program. At the same time, it transmits the signals of the lower-level machine to the monitoring computer to receive the monitoring computer's instructions. III. Water Treatment Process Flow In the wastewater treatment process, the system mainly completes the following control programs and automatic adjustment loops. (1) Program control of coarse and fine screen operation The operation of the screen is automatically controlled by the water level difference before and after the screen. However, when a certain time limit is exceeded, it switches to time control and follows the control sequence of starting the press first, the belt conveyor, and then the sludge rake. (2) Optimization control of the inlet pump room The start of the wastewater pump in the pump room is automatically controlled according to the water level value of the collection tank, and the rotation of the running pumps is controlled. The time accumulation and automatic start of the standby pump can be automatically selected or manually set (can be modified on the monitoring and management computer). (3) Control of grit chamber agitator, water distribution well and anaerobic tank. This control mainly relies on remote control by management computer. (4) Oxygen supply regulation and control of oxidation ditch. The task of the oxygen supply regulation system of oxidation ditch is to maintain the dissolved oxygen value in oxidation ditch within the allowable range to ensure that it maintains the living environment determined by the organisms, achieve the purpose of removing pollutants in the original sewage, and save energy consumption as much as possible on this basis. (5) Sedimentation tank control. (6) Return sludge quantity regulation system and control. The task of return sludge quantity regulation is to ensure that the concentration of mixed liquor in the biochemical treatment system is maintained within a certain range. The regulated quantity is the amount of activated sludge returned to the anaerobic tank. (7) Control of sludge thickening and dewatering machine room . IV. Electrical control diagram of SBR tank treatment section. V. Conclusion . It has been proven that the wastewater treatment system based on PLC control has met the designer's design requirements. It has solved the shortcomings of traditional chemical regulation and further improved the controlled object. With the full promotion of this control system, it will surely further improve people's living environment and make the production efficiency of enterprises steadily increase.