Experimental studies on increasing sedimentation efficiency of vortex settling basin by using submerged vanes

The vortex settling basin is a sediment control structure in conveyance water system which can be more economical than other designs in specific conditions. Deposition of sediment in the basin is a major problem. Mechanism of separates solids and water in these basins, based on flow vortex and difference of density between water and sediments. Therefore the sediment increases in the basin for long time. In this study the hydraulic characteristics of these basins are investigated and offered a method to increase the efficiency of it. In this offer the submerge vans were used on the bed of the basin. Experimental results were showing that increase in deposition with a decreasing vanes interval (rR/2), vanes with guidance sediments toward orifice bottom, flashing from bottom occur more than another. Results also indicated that located vanes with constant total flashing efficiency and flow losses, and has been able to change bottom sediments in the basins. Experiments show that if the vanes are placed in less radial intervals, the discharge loss increases. As well as increase input flow because that total deposition efficiency, hydraulic efficiency and vanes efficiency in flashing have been increased.