DYNAMIC MODELING OF SEDIMENTATION IN THE ACTIVATED-SLUDGE PROCESS

Secondary sedimentation plays a fundamental role in biological wastewater treatment processes where activated sludges are used. In addition to water clarification and sludge compaction, the secondary settler is used as a dynamic storage for the biomass in the system. This role is important for process control since displacing sludge from the settler to the oxidation tank is the main way to adjust process conditions in the short time-scale. The scope of this paper is to present a model for the time-varying behaviour of the total activated mass, taking into account the coupling between the aeration tank and the secondary settler. Numerical simulations show that the model can reproduce any relevant feature of the real system and can be used in control strategy design for sludge management.