This study was performed to investigate the electrochemical oxidation of anionic surfactants. In particular, a synthetic solution of sodium dodecyl benzene sulfonate and a real car wash wastewater were treated by galvanostatic electrolysis using a Ti-Ru-Sn ternary oxide and a boron-doped diamond (BDD) anode. Measurements of the Chemical Oxygen Demand (COD) and the concentration of the anionic surfactants were used to follow the oxidation. Using the Ti-Ru-Sn ternary oxide anode, the complete removal of COD and sodium dodecyl benzene sulfonate was obtained only in the presence of chloride ions that act as inorganic mediators. The oxidation rate was almost independent of current density and electrolyte flow rate. In the case of BDD the mineralisation of the sodium dodecyl benzene sulfonate was achieved in all experimental conditions due to reaction with hydroxyl radicals electrogenerated on the diamond surface during electrolysis. The COD removal rate increased with increase in electrolyte flow rate, indicating that the oxidation was mass-transfer controlled. Comparison of the results of the two electrodes showed that chlorine mediated oxidation at the Ti-Ru-Sn ternary oxide anode allowed a faster COD removal of both the synthetic solution and real car wash wastewater.

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In this paper, the anodic oxidation of a real leachate from an old municipal solid waste landfill has been studied using an electrolytic flow cell equipped with a lead dioxide (PbO 2 ) anode and stainless steel as the cathode. The influence of several operation parameters such as (i) the applied current (from 0.5 to 3 A), (ii) liquid flow rate (from 50 to 420 L h -1 ), (iii) temperature (from 25 to 50°C), and (iv) pH (from 3.5 to 8.2) on the COD removal rate, current efficiency, and energy consumption has been evaluated. The galvanostatic electrolyses always yielded COD values below the discharge limit (COD \160 mg L -1 ); the COD removal rate increased with rising applied current, solution pH, and temperature, whereas it remained almost unaffected by the recirculation flow rate. These results indicate that the organic compounds were mainly removed by their indirect oxidation by the active chlorine generated from chlorides oxidation. The specific energy consumption necessary to reduce the organic load to below the disposal limit was 90 kWh m -3 .

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