Roots blowers Typically, roots blowers and pumps on wastewater treatment systems operate at a constant speed, and their flow rate or water supply is adjusted by changing the valve opening at the blower outlet or the regulating valve opening on the pump outlet pipe. However, the significant feature of both blowers and pumps is that their load torque is proportional to the square of the speed, and their shaft power is proportional to the cube of the speed. Therefore, by changing the motor's constant-speed operation to adjusting the motor's speed based on the required flow, a significant amount of electrical energy can be saved. In wastewater treatment systems, the main function of roots blowers is to oxygenate the biochemical system, ensuring it has ample oxygen. We place an online dissolved oxygen meter in the biochemical pond, set the desired oxygen content in the water on the dissolved oxygen meter, send the data from the online dissolved oxygen meter to the PLC, and then the PLC controls the variable-frequency drive, which in turn controls the roots blower, resulting in a significant energy-saving effect.