The fitness analysis of batch sedimentation test data

The batch settling test is an important method for the sizing of the industry continuous thickeners and the data analysis of the testing is based on the Wilhelm and Naide´s theory, by which the Unit Area can be decided with an approximate expression of settling velocity and solids concentration. The velocities corresponding to the different solid concentrations can be determined through the graphical analysis method or numerical method which can give more precision solution. To handle the test data with numerical method, the expression of the settling curve (the interface height versus the settling time) and expression of the settling velocity curve (settling velocity versus solids concentration) should be selected. In this paper, both of single exponential expressions and double exponential expressions are investigated for the settling curve and single exponential expression, power expression, double exponential expression and rational expression are investigated for the settling velocity curve. The studies showed that the double exponential expression obtained more precision solution in the most situations.