TREATMENT OF OLIVE OIL INDUSTRY WASTES

The waste products derived from olive oil extraction are an aqueous ef fluent (vegetation water) and a solid residue, mainly containing the o live skin and stone (olive husk). Biological purification of the veget ation water is particularly difficult because it contains solids in su spension, and a high concentration of polluting organic compounds and mineral salts. In addition, since the recovery of oil by solvent extra ction from the olive husk is no longer a profitable process, the olive husk has become a waste product that must be disposed of. In this wor k, samples of vegetation water (VW) from olive oil mills were separate d by evaporation into an aqueous liquid (80-90% of the initial volume) , that could then be purified by a traditional biological process, and a residue in which about 98% of the organic load was concentrated. Th e properties of the concentrated VW residue and of the olive husk sugg ested the possibility of using a mixture of the two as an efficient fu el to provide the heat for the evaporation stage. (C) 1998 Elsevier Sc ience Ltd. All rights reserved.