Evaluation of laboratory and industrial meat and bone meal combustion residue as cadmium immobilizing material for remediation of polluted aqueous solutions: “Chemical and ecotoxicological studies”

Meat and Bone Meals (MBM) combustion residues (ashes) are calcium and phosphate-rich materials. The aim of this work is to evaluate ashes efficiency for remediation of cadmium-contaminated aqueous solutions, and to assess the bioavailability of cadmium on Xenopus laevis larvae. In this study both industrial (MBM-BA) and laboratory (MBM-LA) ashes are compared regarding their efficiency. Kinetic investigations reveal that cadmium ions are quickly immobilized, with a maximum cadmium uptake at 57 mg Cd2+/g of ashes for MBM-LA, two times higher than metal uptake quantity of MBM-BA, in our experimental conditions. Chemical and X-ray diffraction analysis (XRD) reveal that Cd2+ is mainly immobilized as Ca10 − xCdx(PO4)6(OH)2 by both ashes, whereas otavite, Cd(CO3), is also involved for MBM-LA in cadmium uptake. Otavite formation could be explained by the presence of carbonates in MBM-LA, as observed by IR. Genotoxicity of cadmium solution on Xenopus larvae is observed at 0.02, 0.2 and 2 mg Cd2+/L. However addition of only 0.1 g/L MBM-LA inhibits these effects for the above concentration values whereas Cd2+ bioaccumulation in larvae's liver is similar for both experiments, with and without ashes.