The Optimisation of Hydrodynamic Vortex Separators for Removal of Solids from Wastewater, using the Continuous Adjoint Method with Topology Modification

Settling tanks are used in wastewater treatment to separate solids from wastewater. The aim of this research is to devise a CFD-based methodology that optimises their performance through modification of their design.

The continuous adjoint method is employed to derive the adjoint equations, associated with the drift flux equations used to model the flow of wastewater. A Darcy porosity term is included to enable a topological modification of the HDVS, and the equations are specialised to optimise the device for the removal of solids from wastewater. They are further specialised to the typical boundary conditions of ducted flows and are coded using OpenFOAM.

A series of optimal designs are found for boundary conditions, corresponding to typical values used in practice, which are shown to improve the performance of the Limmattal settling tank. The designs are compared, based on their performance and capacity.