ABSTRACT
Zirconium occurs in the environment mainly as a constituent of mineral deposits. These deposits are abundant and widespread, but they are not known to pose an environmental or human health threat because they are insoluble and hence essentially unavailable to living organisms. Furthermore, zirconium cannot form covalent bonds with carbon-an important condition for interaction with biological systems-and in fact the metal has no known biological significance. Watersoluble zirconium compounds that are discharged by industry are converted to highly insoluble hydrous zirconia (ZrO2) or zirconium hydroxide [Zr(OH)4] at pH 4-9.5 in wastewater and are deposited as environmentally inert sediments. The solubility product for precipitated zirconium oxide was computed as 1.1 1054 (1).
