LIQUID-SOLID FLUIDISED BED FOR THE ADSORPTION OF HEAVY METALS FROM WASTEWATER

Adsorption of heavy metals for water purification is largely based on the use of activated carbons either in fixed bed columns or agitated vessels. This paper deals with the adsorption of a model cadmium solution over an oxidised activated carbon in a liquid-solid fluidised bed. Experimental studies on the equilibrium and the kinetic characteristics of cadmium adsorption on the selected sorbent and hydrodynamic tests on a lab scale fluidised bed are presented. CFD simulations of the lab scale fluidised bed were carried out with the software Fluent 6.2 by implementing the specific equations to model cadmium adsorption. The CFD simulations provide hydrodynamic results consistent with the experimental observations and, once supported by proper kinetic and thermodynamic studies, allow to clarify the complex relations among hydrodynamics and adsorption phenomena in fluidised beds.