A CFD methodology for the design of sedimentation tanks in potable water treatment Case study: The influence of a feed flow control baffle

Computational fluid dynamics simulations are employed to assess the effect of adding a vertical baffle at the feed section of a full-scale edimentation tank for the improvement of solids settling in potable water treatment. A general CFD-based simulation strategy is developed based n the specific features and conditions met in practice for potable water treatment. The linearity of the particle conservation equations allows separate alculations for each particle size class – but performed for all classes of interest – leading to the uncoupling of the CFD problem from a particular inlet article size distribution. The usually unknown and difficult to be measured particle density is found by matching the theoretical to the easily measured xperimental total settling efficiency. The proposed strategy is computationally much more efficient than the corresponding strategies used for the imulation of wastewater treatment. This work compares simulations from a standard and a baffle-equipped tank. It is found that the baffle decreases he inlet recirculation zone and enhances the settling of solids by directing them towards the bottom of the tank with high velocities. It is noteworthy hat even small differences in the particle velocity can cause large changes in the percent of settled particles; in this work, the overall solids removal fficiency increased when using the baffle from 90.4 to 98.6% leading to a reduction of the effluent solids concentration of approximately 85%. 2007 Elsevier B.V. All rights reserved.