EXPERIMENTAL STUDIES AND SIMULATIONS ON GRAVITATIONAL SEDIMENTATION OF THE SOLID POLUTANTS IN SUSPENSION

Abstract

Sedimentation of suspensions process is important, especially in pollution and biologic studies. Unlike usual methods,as those using pipettes, aerometer or balances, the optical ones are nondestructive and more accurate. During thesedimentation produced by the braked fall off the solid particles in suspension, fluctuations induced by an oppositevertical diffusion occur. We used a scattering method, based on the attenuation of a laser beam, which allows plottingsedimentation curves (the dependence on time of the suspended solid particles concentration) of the process. Weobtained an empirical relation describing sedimentation curves as a function of some main parameters (related toinitial concentration, height in suspension, dimensions of suspended solid particles) and we performed a simulation ofthe experimental sedimentation curves using the obtained relation and Mathcad software facilities. We notice that theresults of these studies allow using a fast method in order to determine the sedimentation time, which often can be verylong.

Keywords

• light scattering
• gravitational sedimentation
• sedimentation time