Transport of solid particles in suspension within a turbulent flow has been studied in physical models of settling tanks consisting of a sloping backward facing step and an outlet weir. Mean and fluctuating velocities have been measured by Laser Doppler Anemometry, particularly in the recirculation region generated by the step. Particles injection allowed to determine percentages of outgoing particles as well as the repartition of scdimcntcd particles. These experimental results were used to assess the influence of the geometry on the settling tank efficiency. Experimental results on velocity fields were compared with a vertical two-dimensional turbulence model (VEST code). Results relative to the transport of particles were confronted to the output of an Eulero-Lagrangian three-dimensional model for the simulation of solid particles trajectories (TRAPS code slightly modified). This code uses as input the mean field calculated by VEST. A good agreement has been obtained on outgoing percentages and on the repartition of sedimented particles.