Composting of wastes produced by low water consuming olive mill technology.

Olive mill pomace (OMP) produced by low water consuming mill technologies (LWCT) were composted with chopped wheat straw in a forced aerated static pile. During the process temperature, oxygen consumption, moisture content, pH, electrical conductivity, total organic carbon, total extractable carbon, humic and fulvic acids, nitrogen, C/N, phenols, lipids and lignin were determined. Urease and casein-hydrolysing protease activities were also assayed. The humification was assayed following the degree of humification, the humification rate and the humification index which respectively reached the values of 0.12, 89% and 15% during the maturation phase. The analyses of final product revealed the presence of considerable amounts of mineral nutrients and stabilized organic matter and absence of harmful levels of heavy metals. The phytotoxicity disappeared at the end of the thermophilic phase.