Selection of cost-effective treatment modules for high saline wastewater produced from the olive mill is a challenging task. The aim of this study is to select the most effective technology applied to treat Olive mill wastewater. Several trials using various techniques were carried out to treat wastewater produced from pickling olives and olive oil manufacturing; for instance, anaerobic-aerobic, coagulation/flocculation, and electrocoagulation. The characteristics of olive manufacturing raw wastewater in terms of total dissolved solids (TDS), chemical oxygen demand (COD) and oil and grease were 10032, 9174, and 914.8 mg/l respectively. The results showed that electro-coagulation technique with aluminum electrodes and operating parameters of 30 voltage and 1.5 hours achieved COD removal rate 84%. However, the residual concentration (900 mgO2/l) still needs further treatment. Aerobic treatment using activated sludge was applied after electrocoagulation. The results showed that the use aerobic treatment after electrocoagulation is more efficient than the use of anaerobic. Analysis of the treated water showed that the maximum COD removal efficiencies were 98% at optimum conditions. The effluent quality meets the discharge regulatory standard. Consequently, the electrocoagulation followed by aerobic process can be considered as a reliable, safe and cost-effective method for the treatment of olive mill wastewater.