Removal of heavy metals from wastewater using infiltration-percolation process and adsorption on activated carbon

Abstract

Heavy metal pollution has become one of the most serious environmental problems nowadays. The removal of heavy metals from wastewaters has attracted a considerable attention because of their adverse effects on public health and ecosystems. The main objective of this work was to investigate the efficiency of the coupling of infiltration-percolation process with adsorption on activated carbon in the removal of heavy metals contained in urban wastewater effluents. The adsorption of heavy metals on a commercial sample of activated carbon was studied in a static mode. Several laboratory experiments made it possible to distinguish the optimum quantity of powdered activated carbon necessary to remove a large range of heavy metals. Results showed that the equilibrium of the adsorption was reached very quickly for cadmium (Cd2+), i.e., after 15 min of contact with the activated carbon. On the other hand, the equilibrium of zinc (Zn2+), lead (Pb2+) and copper (Cu2+) was achieved after 45 min. The withdrawal rates were 70.77% for Zn2+, 64.75% for Pb2+, 67.07% for Cu2+ and 78.42% for Cd2+. The adsorption isotherms determined for Zn2+, Pb2+, Cu2+ were of type I, while the shape of the Cd2+ curve showed a type II isotherm. These isotherms confirm the capacity of the powdered activated carbon to adsorb cadmium better than the other studied heavy metals.