The application of electrochemical technology to the remediation of oily wastewater

The successful application of electrochemical technology, employing a dimensionally stable anode (DSA®), for the remediation of wastewater from the oil extraction industry has been demonstrated. Samples from the oil–water separation box of an effluent treatment plant were submitted to voltammetry, chronoamperometry and electrolysis studies using a DSA anode of nominal composition Ti/Ru0.34Ti0.66O2. Electrolysis of the oily wastewater lead to a time-dependent reduction in chemical oxygen demand (COD) in the sample that could be attributed to: (i) the direct oxidation of oil components at the electrode, by the metal oxide itself or by OH radicals available at the electrode surface, (ii) the indirect oxidation of oil components by intermediate oxidising agents formed in parallel reactions (ex. ClO−), and (iii) the aggregation of suspended oil droplets by electroflotation. The largest reduction (57%) in COD was obtained following electrolysis of an oily sample for 70 h at 50 °C with a current density of 100 mA cm−2. The stability of DSA electrodes for use in oily wastewater remediation has been assessed.