Treatment of re-refining effluent from lubricating oils by combining electrocoagulation and coagulation-flocculation processes
A combination of electrocoagulation and coagulation-flocculation processes was used for re-refining effluent from lubricating oils. The efficiency of the process was evaluated based on the chemical oxygen demand (COD), color, and turbidity of the refined effluent. Electrocoagulation (EC) and coagulation-flocculation parameters, such as the initial pH (3.00, 4.41, and 9.00), and current density (4, 9, and 16 A/m2), and the use of aluminum polychloride coagulant and superfloc A300 flocculant were studied. EC performed at pH 9, with a current density of 16 A/m2 and 7 V, resulted in removal efficiencies of 85.14%, 99.81%, and 99.85%, for COD, color, and turbidity, respectively. The removal efficiencies increased to 96%, 99.87%, and 99.94% for COD, color, and turbidity, respectively, by the further coagulation-flocculation treatment in the presence of 13.8 mg/L aluminum polychloride coagulant and 80 mg/L Superfloc A300 flocculant.