Customer application 31 August 2020
High Precision in the Aeration Basin

Using WAGO technology, H2Ortner from Passau developed a controller module that gives operators of wastewater treatment plants need-based control of the blowers in their aeration tanks determined by the degree of contamination in the wastewater. This type of control saves electricity, lowers the nitrogen concentration in the discharge and increases operational reliability. Practical experience shows that in many cases, plant operators can recoup the investment through the waiver of the wastewater charge alone.

In any modern wastewater treatment plant, there are team members who work around the clock without vacation time or even payment: bacteria that break down harmful substances in the wastewater in the aeration tank. All the microorganisms that are responsible for nitrification – the conversion of nitrogenous ammonia into nitrate – need for their work is oxygen.

Advantages of the WAGO PFC200 Controller:

The controller allows Web-based control and parameterization of the processes.
The clearly organized interface allows all the data to be grasped quickly.
The comprehensive interfaces provide the optimal conditions for communication with various controllers.

Unnecessarily High Charges

The oxygen is injected into the aeration tanks via blowers. In small and medium-sized wastewater treatment plants, these are usually controlled by a timer – regardless of the actual contamination level in the wastewater influent. This approach also bypasses the dynamics of the biological processes in the aeration tank. The process usually operates on that assumption that “more is better”: better to aerate a little longer in order to ensure that the required limiting values are actually met. However, since the blowers require a great deal of power, this approach drives up the energy costs. Furthermore, an excess of oxygen impedes the stage following nitrification – denitrification – in which the nitrates that were generated are then reduced to molecular nitrogen. Therefore, the discharge values are not as low as they could be. The result is that plant operators often have to pay unnecessarily high wastewater charges.

Need-Based Blower Control

These are some of the reasons why H2Ortner, a wastewater purification specialist company from Passau, developed a solution for need-based blower control. The system, which is named “NiDeEco” and equipped with WAGO automation technology, ensures that the aerobic bacteria have an optimal oxygen supply in the aeration tank at all times. “Our controller module allows the operators of wastewater treatment plants to lower the nitrogen concentration in their discharge and simultaneously reduce their energy costs,” explains CEO Josef Ortner. Furthermore, the system makes it possible to optimize the elimination of phosphorus.

Process Dynamics at a Glance

NiDeEco controls the blowers, and thus the nitrification and denitrification, as a function of the level of contamination in the wastewater. The current oxygen, ammonia and nitrate values, which are recorded by sensors – either existing or newly installed ones – are the starting point. The data is wirelessly transferred to the controller module, where a software application determines the treatment performance from the sensor data and then calculates the optimal oxygenation level on this basis. The system uses not the individual values, but rather curve progressions. “This allows us to take the dynamics of the processes into account – a great advantage for precise, accurate control of the blowers,” explains Ortner. In the process, NiDeEco is able not only to directly control blowers, but also to address higher-level controllers.