LABORATORY COMPOSTING ASSAYS OF THE SOLID RESIDUE RESULTING FROM THE FLOCCULATION OF OIL MILL WASTE-WATER WITH DIFFERENT LIGNOCELLULOSIC RESIDUES

The manufacturing process of olive oil yields a highly contaminating r esidue whose elimination supposes a serious environmental problem stil l unresolved in the principal olive oil-producing countries. Nonethele ss, this residue is rich in organic matter and minerals, which makes i ts use as a fertilizer or organic amendment significant to the poor so ils that abound so much in the countries where it originates. In accor dance with its peculiar characteristics, its direct applications could lead to more adverse than beneficial effects, for which reason it wou ld be necessary to carry out a previous composting process in order to utilize it. The principal objective of the present study is to evalua te the quality of different products obtained through the composting o f the solid residue that results from the flocculation of the oil mill wastewater. To facilitate composting, the residue of flocculation (FO MW) was mixed with different lignocellulosic residues (straw, vine sho ots, olive branches and olive husk). The composting was carried out in a climatic chamber in PVC containers having a capacity of 5 litres. S amples were periodically taken which were characterized and analyzed. Except for the mixture of FOMW with olive husk, in the rest of the mix tures assayed, an important degradation of organic matter as well as c ellulose was observed. In addition, a decline of phytotoxicity which t he initial product presented was observed. The results obtained show t hat the composting of this residue, when mixed with others of lignocel lulosic character, is an effective manner of resolving the problem, wh ile generating quality products from the point of view of its agricult ural utilization.