SOLUBILIZATION OF HEAVY-METALS FROM A RIVER SEDIMENT BY A RESIDUE FROM OLIVE OIL INDUSTRY

The effect of the presence of a residue from olive oil industry ('alpechin') on the solubilization of some heavy metals present in a river sediment is studied by equilibrating the sediment with solutions of various concentrations of the residue at various pH values. It is shown that at any pH within the range tested the residue causes a nearly linear increase in dissolved Pb from the sediment as the residue concentration increases. Fe and Cu are mobilized by the residue at the higher pH values tested, but in more acid conditions the solubility of these two metals seems to be lower than in the absence of alpechin. For high alpechin concentrations the concentrations of Fe and Cu tend to a pH-independent value, which can correspond to an equilibrium distribution of metal-organic matter complexes between the two phases. Alpechin does not show any mobilizing effect on Mn or Zn from the sediment, and in the case of Mn the sediment even removes part of the metal originally present in the alpechin solutions.