Recovery and recycling of heavy metals in industrial sludges

Abstract

Elimination and recovery of heavy metals have been achieved on two industrial sludges: a sludge with 0.5% of mercury, and a sludge with 25% of nickel and 16% of cadmium. Concerning the waste with Hg, a distillation under atmospheric pressure has been achieved. Furthermore, we have considered the possibility to use the biomass Rhizopus arrhizus to absorb mercury in the distillate. Preliminary experiments have been performed on a synthesis solution of HgCl 2 at pH=4. Concerning the sludge with Ni and Cd, a chemical separation of Ni and Cd has been realised and then Ni was transformed in Ni(OH) 2 in form of powder.