AUMA actuators with integral PID controllers are successfully controlling dissolved oxygen concentrations in the activation basins at the water and wastewater treatment plant of the city of Podolsk, in the greater Moscow region. This standalone process control solution helps not only to create optimum conditions for the micro-organisms that remove the organic material, but also to considerably reduce energy consumption within the plant.
Compared to using a separate PLC or controller, the actuator-based control system offers a cost-efficient and easy-to-install solution that requires less equipment, fewer cables and less programming.
The AUMA solution relies on an optional PID controller integrated with the company’s intelligent AC actuator controls. The PID controller connects directly to an external sensor. The setpoint can be programmed into the actuator controller, or alternatively taken from a distributed control system. The PID module compares the measured value with the setpoint and adjusts the valve position accordingly.
At Podolsk, the standalone PID controller is used to adjust the flow of compressed air to the activation basins. The control signal comes from an online dissolved oxygen sensor. Based on this value, an AUMA SAR actuator for modulating duty precisely controls the position of a gate valve at the air inlet of the activation basin. Accurate and responsive control means that only the amount of oxygen required for the process is added, so the air compressors can operate at reduced throughput. Since the air supply for the activation basins accounts for a big share of the energy consumption in a water treatment plant, plant operator Vodokanal Podolskiy has been able to reduce its energy costs considerably by implementing the AUMA control solution.
Vodokanal Podolskiy has been using AUMA actuators since 2013. Today, more than 100 SA and SAR multi-turn actuators with AC actuator controls are working reliably throughout the plant. The actuators are integrated into the control system via the robust Modbus RTU protocol.