Removal of lead from aqueous solution by Acinetobacter calcoaceticus

A bacterial strain tolerant to the presence of 400 ppm lead was isolated from digested sewage sludge. The organism was identified as Acinetobacter calcoaceticus var: anitraus (98% confidence). Both viable and formalin-inactivated bacterial cells could remove Pb from an aqueous solution. The Pb-binding ability of inactivated cells was compared with that of a commercial ion-exchange resin. Amberlite IR-120. The metal-binding ability of A. calcoaceticus followed the sequence Pb greater than or equal to Cu greater than or equal to Cr greater than or equal to (Cd, Ni, and Zn) greater than or equal to Co. The ability of the inactivated cells to remove Pb was pH sensitive, and the adsorption process was slightly affected at high temperature (70 degrees C). The adsorption and desorption process worked equally well with A. calcoaceticus embedded in a polyacrylamide gel matrix.