Determination of the Optimum Conditions for the Electrocoagulation of Olive Oil Mills Wastewater (OMW) Using Aluminum Electrodes

The effective performance of electrocoagulation (EC) technique in the treatment of olive mill wastewater (OMW) has been investigated using aluminum electrodes. The electrocoagulation progress was followed by the measurement of COD, turbidity, color, suspended solids, pH, height of liquor, TDS, electric conductivity, electrode and energy consumption, temperature and the quantity of electricity used. The effects of operating parameters such as current density, initial pH, electrolysis time, and distance between electrodes (D), on COD removal efficiency have been investigated. It has been shown that the removal efficiency of COD increased with the increasing applied current density and coagulation time. The obtained results of treatment of OMW, showed that the effectiveness of the reduction of COD and color by electrocoagulation increased with time and D at a constant current density (i=23.55 mA/cm²), the effectiveness of treatment was also increased with decreasing D at a constant voltage (U=15 Volt). It was Found during the evaluation of results obtained in both cases that the optimal distance between the electrodes is D=1.5 cm, and the optimal time of treatment is t=30 min, and the best current intensity is I=4 A, equivalent to a current density i=31.25 mA/cm² when STotal electrode=128 cm². Under these conditions the removal efficiency of COD, dark color, TSS, turbidity, TOC, Phenol, Tannin and lignin, Volatile acids, TIC, and TNb are 22.67, 56.1, 80, 91.31, 28.5, 11.5, 24.32, 26.7, 100 and 100 % from olive mill wastewater respectively. The BOD5 treated/BOD5 raw ratio of the electrocoagulated OMW increased to 2. The electrodes consumption was 0.168 kg Al/kg CODremoved and the specific energy consumed was 3.59 kWh/kg CODremoved.