The paper proposes a methodology for rapid estimation of the mass of suspended solids in the batch settler based on the phenomenon of fractional density changes. The methodology is intended for use in industrial processes and requires no human interaction. It requires the measurement of hydrostatic pressures at two different levels inside the settler and enables: (1) estimation of the total mass of suspended solids before the sedimentation process is finished with accuracy of about 10%, (2) monitoring of the percentage of mass that is still above the height of one of the measurements (separation index), (3) indication of sedimentation finalization at a certain level in the settler and also (4) observation of the compaction of sludge at the bottom of the settler. The separation index can be used to quantitatively specify the separation progress and also as a guide in applications requiring specified increase of the suspended solids concentration e.g. thickening to a specified concentration be settling. (C) 2016 Elsevier B.V. All rights reserved.