Wastewater Treatment Plant Zwanenburg; Ready for the Future

On the outskirts of Zwanenburg, Mobilis—together with Croonwolter&dros, RWB Water and other partners within the Water Treatment Alliance (WZA)—completed the renovation and expansion of the Zwanenburg wastewater treatment plant. The project is part of the integrated AWS programme of the Rijnland Water Authority, aimed at making the regional wastewater system future-proof.

The main challenge was to carry out construction while keeping the treatment plant fully operational. Through a phased construction approach, existing installations remained safely in service while new components were added. Concrete structures, civil works and mechanical installations were carefully coordinated to ensure seamless integration.

The plant was expanded to handle additional capacity from two new pumping stations. Mobilis delivered, among other works, an expansion of the aeration and settling processes, new sludge-line components, durable civil structures, and integration with the electrical and control systems by Croonwolter&dros. Close collaboration within the design-and-build team enabled fast decision-making and continuous technical optimisation.

Sustainability was a key focus in both design and execution. The upgraded facility achieves approximately 15% energy savings and is prepared for future sludge processing at Haarlem-Waarderpolder, where sludge will be converted into biogas.

According to Division Director Remco Lensen, the Zwanenburg project demonstrates what Mobilis stands for: technical craftsmanship, innovation and building with impact. The upgraded treatment plant provides a robust, future-ready foundation for the entire region.