Combined Electrokinetic Soil Flushing and Bioremediation for the Treatment of Spiked Soils Polluted with Organics

Abstract

The work aims at studying the feasibility of the electrokinetic enhanced bioremediation. This is an emerging group of technologies that tries to combine the advantages of the electrokinetic soil flushing technology (EKSF) and biological soil remediation processes. Results demonstrate that combination of both technologies is not easy due to their very different characteristics. Results of direct combination are not completely positive because EKSF produces great changes in the pH and temperature, which affects negatively to the microbial viability. To overcome these drawbacks, different alternatives have been tested in this work in order to improve the efficiency of the combined biological and electrokinetic treatment. This work summarizes the main results obtained in each of them. The best results were obtained using a combination of EKSF with permeable reactive biobarriers in which the microorganisms were supported on gravel (EKSF-PRB). The position of the biobarrier was away from the extreme pH sections, and in this zone the supply of inorganic nutrients was ensured. Experimental results corroborated that the pollutant degradation efficiency is much higher using the combined EKSF-PBR technology (26.8% removal in a 14-day long treatment with an electric energy consumption below 100 kWh m-3) than using the simple biological treatment or the EKSF (11.8% removal in the same 14-day long treatment period).