Hydrodynamic simulations of aeration tanks of activated sludge wastewater treatment plants in Algeria - three case studies

Abstract

Most wastewater treatment plants (WWTP) currently in operation in Algeria use the activated 3 sludge process. The aim of this study was to investigate the hydrodynamic behaviour of aeration tanks of three WWTP located at Chelghoum Laid, Souk Ahras, and Annaba City, Algeria. These WWTP differ by the dimension and geometry of the basins and by the aeration systems. In aeration basin hydrodynamic is crucial for the WWTP efficiency. Measurements velocities were carried out at the WWTP of Chelghoum Laid City having a small-scale model of 2 m length, 0.66 m of width and 0.15 m height. Water velocity measurements were taken at three levels (top, middle and bottom) for five sections (a, b, c, d, e), each comprises nine points. Simultaneously, a numerical simulation by computational fluid dynamics (CFD) was implemented for the three WWTPs. According to the basin section and level, velocities varied strongly, from 0.8-2.5 m/s at the top; 0.6-1.5 m/s at the middle and in the order of 0.2 m/s at the bottom. Results from CFD are in good agreement with experimental data of Chelghoum Laid WWTP basins.