Contact us

Project’s context & challenges

Waterschap Rijn en IJssel aimed to upgrade WWTP Winterswijk to further improve the water quality of the Groenlose Slinge, a sensitive lowland stream with vulnerable ecosystems. The existing wastewater treatment plant, designed for a capacity of 92,000 population equivalents (PE) and a flow of up to 860 m³/h, required an advanced treatment step to remove nutrients and pharmaceutical residues more effectively.

The challenge was to implement a future-proof and robust treatment concept capable of removing micropollutants, phosphorus, and ammonium while minimizing ecological risks and avoiding harmful by-products such as bromate. At the same time, the solution had to integrate seamlessly with the existing treatment infrastructure and support long-term operational flexibility.

Customer benefits

More than 90% removal of micropollutants across the full treatment train

70% removal of 7 out of 11 guiding pharmaceutical substances

Significant reduction of ecotoxicological impact on receiving waters

Ammonium reduced to below detection limits

Low bromate formation due to optimized ozone dosing

Future-proof and flexible plant design using the Verdygo modular concept

Plant capacity

92,000

PE

860 m³/h

(Up to) Flow capacity

Solution

To achieve these ambitious treatment targets, a fourth treatment stage was implemented consisting of ozonation followed by biological activated carbon filtration (BAKF) and chemical coagulation. This integrated treatment concept ensures efficient removal of micropollutants while simultaneously improving nutrient removal and overall effluent quality.

Nijhuis Saur Industries acted as technology supplier, delivering the MicroOxi ozone technology and chemical coagulation system, and contributing to the engineering of the advanced treatment process as part of the CLC Water partnership. The ozone step plays a key role in breaking down pharmaceutical residues and enhancing the performance and lifespan of the downstream biological activated carbon filtration.

The installation operates as part of the Verdygo modular design concept, an innovative approach that uses standardized treatment modules. These modules can be easily added, replaced, or adapted, enabling flexible scaling and continuous optimization of the treatment process.

Scope of supply

  • Technology supply for MicroOxi ozone system

  • Supply of chemical coagulation system

  • Process engineering contribution for the advanced treatment stage

  • Support during commissioning and startup

Applied solutions

  • Ozone oxidation technology (MicroOxi)

  • Biological activated carbon filtration (BAKF)

  • Chemical coagulation for enhanced nutrient removal

  • Modular WWTP design based on the Verdygo concept

Contact our experts for more information

Learn more