Integrating hydrodynamics and biokinetics in wastewater treatment modelling by using smoothed particle hydrodynamics

•Novel integrated wastewater treatment model based on smoothed particle hydrodynamics.•Application of the smoothed particle hydrodynamics method in the field of wastewater treatment.•Effects of unsteady flows and hydraulic mixing on the spatial distribution of biokinetic compounds are computed.•Computational fluid dynamics and process-based wastewater treatment model are simultaneously solved.

In this work a novel integrated biokinetic wastewater treatment (WWT) model based on the smoothed particle hydrodynamics (SPH) method as hydraulic model is proposed. Significant outcomes of this work are the computation of a detailed spatial distribution of compounds in WWT basins and the quantification of the effects of the stirrer induced mixing on the evolution of compounds. SPH is a meshfree particle method which herein is applied to compute a treatment plant's reactor hydraulics. The characteristic feature of SPH is to describe a fluid's dynamics by particles that move along with the flow. The present WWT model takes advantage of this principle by assigning the compounds' concentrations, which are defined by the activated sludge model no. 1, to SPH particles. A full-scale treatment plant simulation with a variable stirrer induced mixing intensity in the denitrification basin is performed. A spatial distribution of the compounds' concentrations, which up to now was unknown for unsteady flows, is computed and analysed. The developed framework is generic and therefore expected to be applicable for modelling chemical engineering processes which are influenced by hydrodynamic effects.