Influence of electric field on the remediation of polluted soil using a biobarrier assisted electro-bioremediation process

In this work, it was carried out the study of the electro-bioremediation of soil polluted with diesel by means of combined electrokinetic soil flushing and biobarriers, using bench scale setups and fourteen days-long tests. Two different biobarriers were evaluated: one of them was developed in the laboratory, with a culture of diesel-degrading microorganisms supported on gravel particles (BB1); the other was obtained by mixing directly clay soil with activated sludge obtained in a municipal wastewater treatment plant (BB2). Biobarriers were placed in a central point of the soil section to be treated, to prevent the negative consequences of pH fronts on microorganisms viability. Potential difference of 0.5 and 1.0 V cm−1 were applied. For the promotion in the transport of the diesel to the biobarrier, a surfactant solution was used as electrolyte (flushing fluid). Results confirm that negative influence of the extreme pH fronts on the microbial viability can be prevented using this electro-bioremediation approach. In the same way, uniform diesel removal was obtained all over the soil by using the surfactant solution. After fourteen days of treatment, in the experiments using the BB1, 19.36% and 27.36% of the total amount of diesel present in the soil were removed applying 0.5 and 1.0 V cm−1, respectively. In the experiments using BB2, 23.33% and 29.10% referred to the total amount of diesel were removed after the fourteen days tests at 0.5 and 1.0 V cm−1, respectively, indicating that the non-specific barrier is slightly more efficient despite not containing an acclimated culture.