Design of lamella separators. Part 2

A method has been developed to predict the minimum angle at which solids will flow down the lower inclined surface of a lamella separator. It is based on a frictional analysis and requires experimental data from a simple batch rig. This method should help to eliminate problems with sludge build-up in lamella separators. The minimum angle was dependent on particle size, shape and surface texture, liquid viscosity and surface tension and the type of settler material. The degree of variation in the underflow solids concentration with time was also examined. It was found to be dependent on settler length, angle and a well-established flow regime. The mode of sludge flow and the mode of settler operation had no effect. [Continues.]