This study focuses on the evaluation of the Electrokinetic Soil Flushing (EKSF) strategy to remediate soil following a simulated spill of the herbicide oxyfluorfen. EKSF is attained by placing (in the soil mockup) two rows of electrodes of different polarity facing each other. The results are compared with those obtained in a reference experiment in which the same spill was simulated and no remediation actions were taken. In addition to the daily monitoring of the most important parameters in the flows, after the remediation test, a post-mortem analysis was performed to obtain a 3-D map of the pollutant distribution. Those results demonstrate that despite the hydrophobic character of oxyfluorfen, it can be efficiently transported by EKSF. Hence, after 34 days of treatment, a 26.8% improvement in the removal of oxyfluorfen was achieved (explained in terms of the effect of the electric field on the pollutant) compared with the reference experiment 2 in which only volatilization can explain the removal of the herbicide. Comparison of the removal of oxyfluorfen by EKSF with that of 2,4-D (studied in a previous study) demonstrates that comparable dragging to the cathode and volatilization are obtained. However, the lower efficiency of the transport of oxyfluorfen by gravity fluxes and electromigration (explained because it is contained as micelles) yielded worse performance of EKSF for this water-insoluble pesticide and hence less efficient remediation. This contradictory result reveals the importance of tests at large-scale facilities such as that used in this work to predict the performance of real systems in future full-scale applications.

In this work, an accidental spill of Fluoxyl (commercial herbicide containing oxyfluorfen) is simulated in a pilot plant with a soil volume of 70x50x50 cm 3. The transport of Fluoxyl obtained by the free diffusion of pollution and under the application of the electrokinetic fences (EKF) technology are compared in a 34-day treatment. In addition, the temperature, conductivity, and pH are monitored daily. At the end of the experiment, a post-mortem analysis is carried out in order to obtain a 3-D distribution map of the pollutant. The results show that EKF is a good technology to remove oxyfluorfen from the soil without excavation because it is able to attain a fast transfer of oxyfluorfen to the flushing fluid used. After 34 days, the decrease in the concentration of oxyfluofen in the

In the treatment of a polluted soil, the pH has a strong impact on the development of different physicochemical processes as precipitation/dissolution, adsorption/desorption or ionic exchange. In addition, the pH determines the chemical speciation of the compounds present in the system and, consequently, it conditions the transport processes by which those compounds will move. This question has aroused great interest in the development of pH control technologies coupled to soil remediation processes. In electrokinetic remediation processes, pH has usually been controlled by catholyte pH conditioning with acid solutions, applied to cases of heavy metals pollution. However, this method is not effective with pollutants that can be dissociated in anionic species. In this context, this paper presents a study of the electrokinetic remediation of soils polluted with 2,4-Dichlorophenoxyacetic acid, a common polar pesticide, enhanced with an anolyte pH conditioning strategy. A numerical study is proposed to evaluate the effectiveness of the strategy. Several numerical tests have been carried out for NaOH solutions with different concentrations as pH conditioning fluid. The results show that the anolyte pH conditioning strategy makes it possible to control the pH of the soil and, consequently, the chemical speciation of pollutant species. Thus, it is possible to achieve an important flux of pesticide into the anolyte compartment (electro-migration of anionic species and diffusive transport of acid species). This way, it possible to maximise the pesticide accumulation in this compartment, allowing a much more effective removal of pollutants from the soil than without the anolyte pH conditioning strategy.