The Slottshagens Reningsverk treatment plant, serving the city of Norrköping, Sweden, and the surrounding area, receives about 45 million liters of wastewater every day. In 2022, the plant’s inlet station required an extensive concrete renovation. Nodra AB partnered with Xylem to plan and install a major bypass to redirect water from the inlet station.
To ensure that the Slottshagens treatment plant could continue operating without compromising safety, a 70-meter-long pipe bridge was constructed over the entire building. Adding to the complexity of the bypass, the pumping solution also needed to account for varying flows during the daytime and nighttime.
While we are accustomed to delivering large, turnkey solutions, the scale and scope of this project is in a whole new dimension, says Adam Drakeley, Xylem Europe’s Senior Applications Engineer. Even seasoned municipal engineers will tell you that diverting an entire city’s combined rain and wastewater over a 70-meter pipe bridge is no mean feat. Meticulous hydraulic, construction and electrical planning was key.
To handle the peak wastewater flows during the day, Xylem installed four Flygt CZ 3501 pumps, with one of the pumps acting as a backup. To handle the lower flows at night, two Flygt NZ 3202 pumps were also installed.
One of the challenges with this project was understanding the different flow levels, says Sargon Melki, Sales Manager Rental, Xylem. When the flow goes down quite a lot at night, you can’t use the bigger pumps, but you also have to be careful when starting up the bigger pumps during the day. If you start the big pumps too fast, you can create a pressure wave in the pipeline, which can damage the system.
Another challenge with the bypass project was fitting the pipeline inside the treatment building.
Xylem’s team, with extensive expertise in bypass solutions and a wide range of equipment available to them through Xylem’s rental bank, was able to quickly design a solution that fit Nodra AB’s requirements.
After about a week of testing, the team had a good understanding of the treatment plant’s flows and adjusted the bypass solution to provide trouble-free pumping during the entire renovation.
The Xylem team also monitored the bypass live through the customer’s AquaView SCADA system. If any problems arose, Xylem had a local team standing by 24/7 to respond within minutes.
Our service team was just five minutes away, which was a big advantage for the customer, says Melki. The customer could also monitor the bypass operations on their smartphone through AquaView, which sends out alerts if there are any issues that need to be addressed.
