Small plants, big demands
Across Denmark’s approximately 800 wastewater treatment plants (WWTPs), the largest and most advanced facilities treat around 90% of the wastewater. The remaining 10% is processed by smaller plants, which often operate under tight financial constraints. These smaller WWTPs typically resort to manual and fixed-point dosing methods to meet effluent requirements. However, this inelastic method is time-consuming and frequently leads to excess dosing and elevated costs due to fluctuating phosphorus concentrations.

With a capacity of 12,500 PE, Otterup WWTP previously administered a manual and fixed-point dosing method of iron based coagulants for phosphorus removal.

Since 25 November 2024, our chemical dosing has been controlled by a BSS SoftSensor, which has performed very satisfactorily with the promised cost savings without the phosphorus concentration in the effluent increasing.
— Arne Michelsen, Technical Coordinator, VandCenter Syd (VCS)

BSS SoftSensor
In collaboration with VandCenter Syd (VCS), BSS has engineered a budget-friendly software alternative to traditional manual and fixed chemical dosing methods. By utilising historical sensor data from existing plant sensors, the solution enables optimised and reliable chemical dosing without requiring new hardware. Furthermore, the adaptable software can integrate with any sensor type, accommodate new chemicals, and be adjusted to unique operational demands.

At Otterup WWTP, BSS SoftSensor was installed in a matter of hours. And after just a few weeks of operation, the facility observed notable reductions in the dosed amount of coagulants as well as a projected a return on investment within two years.

Annual coagulant dosages cut by 23%
The implementation of BSS SoftSensor at Otterup WWTP resulted in yearly savings of EUR 6,300 (DKK 47,000), driven by a 23% decrease in the amount of dosed coagulants. This improvement also yielded an environmental benefit as CO₂ emissions were reduced by 9.81 tonnes each year.

The SoftSensor provides a high degree of security as it is also programmed with a fallback solution, where it reverts to a fixed set point and sends an alert to the SCADA system if a data transmission error occurs. Together, this contributes to optimal operation with a minimum of daily analyses.
—Arne Michelsen, Technical Coordinator, VCS

Optimised polymer dosing for sludge dewatering
To regulate and enhance chemical dosing control, BSS SoftSensor utilises machine learning. This enables the software to learn autonomously from historical and ongoing sensor measurements and improve chemical dosages through continuous adaptation.

In addition, the software’s digital library allows for the integration of new chemicals, ensuring flexibility and adaptation to unique operational demands. Building on this versatile technology, BSS SoftSensor is set to enable optimised polymer dosing for sludge dewatering by the end of 2025.