Soil flushing and simultaneous degradation of organic pollutants in soils by electrokinetic-Fenton treatment

This study focuses on the evaluation of a combination of electrokinetic technology and Fenton's process to remediate a soil polluted with organic compounds. To determine the influence of the several variables such as hydrogen peroxide dosage, iron soil concentration and porosity, different experiments using kaolinite spiked by Rhodamine B were performed. The use of this coloured sample permitted an easy monitoring of the oxidation reactions across the soil bed. From the obtained results, it is concluded that the highest colour removal rate was reached when a solution of hydrogen peroxide around 10% was used, and slight influence of iron soil concentration was detected at the range of concentrations used in these experiments. In all cases, citric acid was added in the anolyte and catholyte solutions in order to solubilize the iron as Fe-citrate complex and to keep the pH in acid environment favouring that the Fenton's reactions take place into the soil. Based on these preliminary experiments, the electrokinetic-Fenton process was applied to total petroleum hydrocarbons (TPH) polluted soil. After 15 and 27 days of treatment, a homogeneous removal of pollutants, around 54.4% and 58.2% of TPH removal efficiency, was reached, respectively. In addition, the Microtox bioassays confirmed the reduction of the Vibrio fischeri inhibition after the soil treatment. Summing up, in situ electrokinetic-Fenton treatment seems to be a suitable technique for the remediation of organics such as hydrocarbons present in polluted soils.