Study and Investigation of Secondary Sedimentation Tank Equipped with Lamella using Discrete Phase Model (DPM)

Water softening and preventing of scaling in evaporators are very important in industrial water treatment processes. Lamella clarifiers improve the treatment process and decrease its related costs. In the present study, by using a CFD approach, the flow inside the sedimentation tank equipped with lamella has been studied. By using the Discrete Phase Model (DPM) and due to the two-way coupling between the main phase (fluid) and the discrete phase (particles), the particles motion has been traced. The turbulence model k-ε RNG is used to simulate the flow inside the sedimentation tank. The influence of employing lamella plates and their inclination angle as well as size of particles have been conducted. Results showed that using lamella inside the tank, by tuning the rising velocity of water, turbulent flow energy, and reduction of the rotational area volume, leads to increase of the tank particle removal efficiency by 6.47 percent. In addition, the presence of lamella causes a stability in the removal efficiency of sedimentation tank at different flow rates. A parametric study with the aim of investigating the effect of different angles of lamella on the tank efficiency shows that changing the angles of the plates from 60 to 45 degrees increases the efficiency by 14.66 percent.