effects of curvature submerge vane in efficiency of vortex settling basin

in this century due to population growth, the use of river water has become more complicated. since most rivers pass across loose and erodible areas, they always act as the most important factor of transferring eroded materials from the solid crust of the earth.  vortex basins are among the solutions known for the high-speed separation of solids from liquids (filtration). one of the problems of such basins is the settling of sediments in their floor which necessitates the performance of required investigations and researches in order to present a method to exclude or reduce such sediments. the present research presents and investigates a plan to resolve this problem. this paper proceeds to perform an experimental study on the effect of a group of curvature submerged vanes in different positions at the floor of a vortex settling basin with a 90ᵒ radial section on the efficiency of the basin. the experiments were performed on a physical model with 96 cm height, 206 cm diameter, 10% floor slope, tow discharges of 45 and 37 l/s, and three orifices with 59, 46 and 36 mm diameters. uniform aggregate (d50=0.22 mm) was applied in experiments. the efficiency of the basin was determined in six different positions of curvature submerged vanes and the values were investigated compared to each other. the results of experiments showed that the efficiency is higher when the vanes are placed more distant from the orifices while changes in orifice diameter and discharge considerably effect on the efficiency.