Facelift for sewage treatment plant

Facelift for sewage treatment plant

SPANGLER – the Plus of Progress.

Actually, it is already well equipped, the sewage treatment plant of Bad Tölz: it has several PLC controls and a control system, a screen plant and a sludge dewatering with subsequent solar drying. However, most of the components, among them the control units, are already between 15 and 20 years old – therefore, it is time to bring the plant up to the current technical standard, especially since spare parts are not available anymore.

With its retrofit programme Spangler Automation has a suitable package in its portfolio to bring the entire automation technology up to date. Therefore, the possibilities for remote control have to be extended, the speed and stability of the system must be improved and the application of the control software and the training of the employees must be simplified. Last but not least, a secure supply of spare parts also plays a decisive role.

Extensive modification of the control technology

“Due to its size we have divided this project in six steps“, reports Maximilian Mayer, deputy manager of the department Service & Installation at Spangler. As a first step, the previous main control Siemens S7-400 was replaced by a S7-1516. It already controls the plant technology (pumps, blower, etc) in the main building; for the time being the old hardware supports it only as regards communication. As soon as the controls will be changed in the adjoining building and the communication to the process control system is completely changed to ethernet in further steps, the old plant will be switched offline.

For this, Spangler uses fiber optic cables to create the basis for the set-up of the ethernet network. Every component includes a central switch, which are connected in ring topology. „As fiber optic cables are particularly characterized by long transmission paths, they are ideal for covering the extensive area in terms of network technology “, says Mayer. Even under rough circumstances a reliable data transfer is guaranteed.

Changeover from Profibus to Ethernet

Before the final transition to ethernet can be completed, Spangler experts firstly split up the existing Profibus system into segments. To connect such a segment then to the new network they first renew the respective control and subsequently all associated peripheries. Assemblies of Siemens S7-1500 and ET200SP series as well as products from Siemens SCALANCE family will be applied.

During the changeover all programmes will be migrated to the TIA Portal which is cross-sectoral applicable or will be installed anew there. An exchange of more control units and the final conversion from Profibus to ethernet will be completed by end of 2023.


Control system technology with new intelligence
Parallel operation of old and new control











Wastewater treatment plant Bad Tölz an der Isar
Bird’s eyeview of the sewage treatment plant (source: Wastewater treatment plant Bad Tölz an der Isar)