Proceedings

In this paper, we describe the computational fluid dynamics method and how it can be used to calculate
flow and solids load distributions in different situations. Two cases studies are presented which highlight
different models which are required in the CFD calculations. In the first case study, an inlet works was
known to distribute solids non-uniformly to eight primary tanks. CFD models were used to determine the
flow and solids load distribution for different retrofit modifications and to determine the optimum
configuration before construction. In the second case study for final tanks distribution, the CFD models
were used to calculate the flow and loads distribution, and hence the total solids loading to eight final
tanks. Although the CFD models showed that both the flow and solids load distribution was poor, the two
effects tended to balance each other giving relatively uniform total solids distribution to the final tanks.
This work highlights the different CFD models which are required for discrete particle settling and
hindered settling in inlet works and activated sludge process respectively. The importance of calculating
the shape of the free surface upstream of flow distribution flumes is also discussed.

Key Words
Computational fluid dynamics, flow distribution, solids load distribution, wastewater treatment works
optimisation