Abstract
Olive mills wastewater (OMWW) is the liquid by-product of the olive mill industry produced in large quantities in Mediterranean region. Due to cost issues no treatment plants are currently available at the mills; therefore OMWW is normally discharged into evaporation lagoons/ponds or spread into the agricultural land. The objective of this research was to quantitatively assess the impact of the olive mills wastewater on the environment. The study was started by the selection of twelve olive mills using different oil extraction techniques (traditional and continous) for environmental auditing. The chemical characteristics of the wastewater were used to estimate the pollution loads per ton of olives processed. Results showed that traditional mills produced the highest pollution load per ton of olives processed. They produced 20.50 kg/t of BOD5, 52.50 kg/t of COD, 20 g/t of phenol and 26 kg/t of total suspended solids (TSS). The two phase mills produced the minimum pollution load, which can be considered as environmental friendly machine. They produced 25 g/t of BOD5, 150 g/t COD, 0.29 g/t of phenol and 6.7 g/t total suspended solid. The COD/BOD5 ratio was 2.5 for traditional and 3-phase mills indicating that this wastewater is not suitable for biological treatment.