INFLUENCE OF INLET AND OUTLET CONFIGURATION ON THE FLOW IN SECONDARY CLARIFIERS

A numerical model for predicting the flow in clarifiers is presented w hich accounts for density-affected and turbulent flow as well as for t he settling of activated sludge. The reliability of the two-dimensiona l model is demonstrated through verification by means of a laboratory experiment which was specially designed for this purpose. The numerica l model is then applied for an evaluation of inlet and outlet arrangem ents. The inlet is positioned at the bottom and the inlet aperture is varied. An outlet at the top of the end wall is compared with outlets longitudinally extended at the surface. The alternatives are assessed by analysis of streamline patterns, layer characteristics and the entr ainment into the bottom current, i.e. the increase of its flow rate. T he study demonstrates how numerical modelling can be used for systemat ic evaluation of the effect of geometrical configurations on the flow in secondary clarifiers. Copyright (C) 1996 IAWQ.