Towards improved 1-D settler modelling: impact on control strategies using the Benchmark Simulation Model

A new 1-D model for the secondary clarifier was recently presented. The decisive difference to traditional layer models is that every detail of the implementation is in accordance with existing PDE theory. Moreover this new model does not only focus on hindered settling but also allows accounting for compressive settling. In this contribution, the behaviour of this new settler model is compared with the traditional settler model of Takács et al (1991) in terms of the impact on underflow predictions, sludge inventory in the plant and control actions by using the Benchmark Simulation Model n° 1. The numerical results show that the new settler model allows for more realistic predictions of the underflow concentration. The improved model clearly has a profound impact on the operation and control of the entire treatment plant and is recommended to be used as of now in WWTP modelling.