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Optimizing small-sized sewage treatment plants

Energy-efficient equipment and a user-friendly state-of-the-art control system reduce the employees’ workload and save money for the municipality through lower energy costs. A true win-win for the environment, people and the municipality.

It is a freezing cold morning in the small municipality of Prosselsheim, just a few kilometers northeast of the city of Würzburg in Germany. A team from SüdWasser, a municipal and industrial water and wastewater utility service provider, is working with Siemens to replace the level monitoring system in a sewage intake lift station of the Prosselsheim sewage treatment plant. A new radar level meter will continuously monitor the level in the pump station and transfer the readings to the SIMATIC WinCC Unified control system for documentation, visualization and archiving. This solution will enable Elmar Scholl, who works for the Prosselsheim municipality, to adjust the switch points for the sewage pumps at any time and optimize lift station performance – including while on the go or at home, thanks to flexible remote access via web browser.

Estenfeld Prosselsheim sewage treatment plant Aerial shot
Headshot of Michael Werner

From the ’90s to the year 2024

The radar level meter is the latest addition to the sewage treatment units in the small plant with a processing capacity of only 1,500 population equivalents. Plants of similar size can be found all over Germany – and the initial situation before the upgrade was also quite typical for such plants, as SüdWasser engineer Michael Werner recalls: “The sewage treatment plant was put into operation in 1993. Thirty years later, many units installed in the plant were no longer up to today’s efficiency standards, and the control technology was also showing its age.” This was why Prosselsheim contracted SüdWasser to implement a complete overhaul of the plant: “We essentially updated all the process and control technology with state-of-the-art systems.”

We updated all the process and control technology with state-of-the-art systems.
Michael Werner, Engineer, Südwasser
The plant has to run in automatic mode as much as possible and deliver the best results with minimal time investment.
Elmar Scholl, Prosselsheim Municipality
The crew took out the old cabinet, put in the new one, and connected the system, and in the evening of the same day, the plant was up and running. Hats off!
Elmar Scholl, Prosselsheim Municipality

Requirements: Reliability, efficiency and ease of operation

Prosselsheim is a small municipality, and time and staff for operating the sewage treatment plant are scarce resources. When selecting a suitable control system, reliability was what counted most, says Scholl, who works for the municipality’s infrastructure services department: “Monitoring and operating the sewage treatment plant is just one of my responsibilities. I am on-site only for the daily measurements and checkups; the rest of the time I need the plant to run in automatic mode as much as possible and deliver the best results with minimal time investment.”

Estenfeld Prosselsheim sewage treatment plant Portrait Elmar Scholl
Estenfeld Prosselsheim sewage treatment plant local operator panel

A compelling package for the control system

Choosing the right control system for the plant was not just a matter of pricing for Prosselsheim and SüdWasser, “even though this is, of course, an important aspect for small municipalities,” says Werner. For Scholl, the deciding factor was the positive feedback from operators in the sewage treatment plant of a community in the vicinity of Prosselsheim: “We asked the operators there if they’re satisfied with the solution, especially when there’s a problem. What they told us was that Siemens provides outstanding support as a project partner: one phone call, and the problem gets solved.” In the end, the Siemens modernization package fit the bill, and Siemens won the contract to supply and integrate the electrical and control systems – “and that was the right decision,” confirms Werner.

All operator actions look and feel the same on a PC, the local operator panel or a mobile device.

Reliable monitoring and documentation on-site and remotely

Since 2023, the Prosselsheim sewage treatment plant has been using an integrated solution for the control system and plant automation from Siemens. Remote distributed systems, such as the stormwater overflow tank, are connected to the control system and the remote maintenance system via secure VPN (Virtual Private Network) -based cellular network access using Telecontrol Server Basic, ensuring that there are no system interruptions here either. All operations can be monitored and controlled in SIMATIC WinCC Unified, including via a mobile Tablet PC. Remote access requires only a web browser, so the solution needs no maintenance, and the integrated cybersecurity features ensure secure remote access, which is essential for any critical infrastructure system.

A middle-aged man looking at a tablet.
Estenfeld Prosselsheim sewage treatment plant Analyzing plant behavior

Seamless modernization in just one day

Siemens designed the solution for Prosselsheim to serve as a type of blueprint for other small sewage treatment plants. The standardized and harmonized components support easy modernization of the control and automation systems, a promise that Siemens was able to fully live up to in Prosselsheim, as Scholl recalls: “Buffering the water for several days is not an option for our plant, so the modernization had to take place during ongoing operation.” And this is exactly how the changeover happened: “In just one day, the crew took out the old cabinet, put in the new one, and connected the system, and in the evening of the same day, the plant was up and running. Hats off!”

Smooth transition

Moving from the old system to the new was just as smooth for Scholl. All operator actions look and feel the same on a PC, the local operator panel or a mobile device, making the system very intuitive: “It really is very easy to work in the system and, for example, adjust set points,” says Scholl. “I log in, click once, and know what I have to do. No training course needed.” The intuitive solution requires minimal training effort, so colleagues can easily fill in for Scholl when needed. Annika Schultheiß, a water treatment technician at SüdWasser, confirms this. She supports sewage treatment plant staff, including Scholl, with optimization on-site and also likes working with SIMATIC WinCC Unified herself: “I can, for example, easily follow the system’s behavior using the trend view – the modifications we made, the changes in the plant, the outcome.”

Estenfeld Prosselsheim sewage treatment plant mobile operation
Estenfeld Prosselsheim sewage treatment plant tanks

Transparency supports process optimization

And the results of the modernization project are already impressive: The replacement of the old process units alone saves about 500 kWh of power for the municipality per day. “That has already earned me praise from the mayor,” says Scholl with a grin. All energy consumption data are recorded by SENTRON PAC devices and transmitted to the control system. The improved transparency with the new control system will help Scholl and Schultheiß in future process optimizations as well: “We are working on further improving treatment performance and energy efficiency,” says the technician.

Automatic notification and alerts

Should something not work as planned in the plant, Scholl is automatically notified via text message. Soon, this notification will be complemented by the Alarm Control Center app from Siemens Solution Partner Alarm IT Factory. The app sends relevant notifications, message statuses and team availability to the specified recipients. Another handy feature: high-priority nighttime alerts trigger a mobile phone ringtone that is repeated until the message has been acknowledged.

Estenfeld Prosselsheim sewage treatment plant control system

Regulatory reporting with little more than a mouse click

Combining the control system with the WinCC Add-on PM-ANALYZE also replaces the laboriously maintained paper-based operation log. All data are recorded digitally, so Scholl can track and analyze data from different sources, including the results of manual probes and measurements. One feature that reduces the workload significantly is the creation of mandatory reports for the DWA (German Water, Wastewater, and Waste Association) and transmission via the DABay interface. Scholl is particularly grateful for this feature: “Before, we recorded the process values in our logbook and had to manually compile and analyze these values, which took two or three days. And, of course, calculation errors and mistakes happened.” Now, DWA-compliant reporting only takes four or five hours: All data are compiled in the appropriate template with one click. The only thing left to do is check the report and send it to the water authority.

Improved understanding of the treatment process

For Werner, the benefits of the new control system extend beyond improving daily operation and plant efficiency; the system also gives operators better access to the plant and the data from the plant, without requiring expensive sensors. “You can do more with the data you have. That allows you to better control the treatment process. That gives the operators the confidence to test new strategies – and thus the new control system leads to a better understanding of the treatment process as a whole.” Integrating the lifting station will also no doubt contribute to this improved understanding. The call for tenders for upgrading the remaining remote stations is already being prepared, says Werner, “and it would be nice if Siemens were to secure those contracts as well.”

It is really very easy to work in the system and, for example, adjust set points. I log in, click once, and know what I have to do. No training course needed.
Elmar Scholl, Prosselsheim Municipality
I can easily follow the system’s behavior using the trend view – the modifications we made, the changes in the plant, the outcome.
Annika Schultheiß, Water Treatment Technician, SüdWasser
It used to take two or three days to manually create the regulatory reports. Now it’s a fully digital process, without errors, completed in just a few hours.
Elmar Scholl, Prosselsheim Municipality
You can do more with the data you have. This leads to a better understanding of the treatment process as a whole.
Michael Werner, Engineer, SüdWasser

The blueprint for small sewage plants

Siemens supports the modernization and automation of small sewage treatment plants like the Prosselsheim facility with a comprehensive hardware and software package that contains all the necessary components for transparent plant operation: SIMATIC WinCC Unified as the control system and as the second level of operation via operator panels, SIMATIC controllers for plant automation, SENTRON PAC energy monitoring systems, telecontrol and the WinCC Add-on PM-ANALYZE for data analysis and DWA-compliant reporting. The package can easily be adapted to specific requirements and is engineered entirely in TIA Portal. To further simplify project engineering, Siemens provides users with a free application example. Plant operators and system integrators thus benefit from a comprehensive solution with an excellent price-performance ratio.

Automate sewage plants with WinCC Unified
Estenfeld Prosselsheim sewage treatment plant application example