LAND TREATMENT OF OLIVE OIL MILL WASTE-WATER

Experiments carried out in lysimeters filled with two calcareous claye y soils (ca 40% CaCO3; ca 40% clay), showed that a 2m layer of soil al most completely removed the organic and inorganic components of olive oil mill wastewater (OMW) when it was applied in doses of 5000-10000m( 3)ha(-1) year(-1). This efficiency was maintained for at least 2 years . In field experiments, the application of OMW to one of these soils d uring three successive years at an annual rate of up to 6000m(3)ha(-1) caused changes in some chemical properties of the soil, especially in the upper layer (0-50cm). Concentrations of soil organic matter, Kjel dahl N, soluble NO3 and available P increased enhancing soil fertility . On the other hand, soil electrical conductivity and sodium adsorptio n ratio also increased but below the levels representing salinization or sodification hazard for the soil. Furthermore, leaching of Na+ and NO3 below the Im layer were detected. (C) 1997 Elsevier Science Limite d.