Electrochemically assisted fences for the electroremediation of soils polluted with 2,4-D: A case study in a pilot plant

Soils polluted with 2,4-D (model of ionic herbicide) can be remediated using a fence of alternating anodes and cathodes surrounding the main contamination point. This works reports results obtained in case study consisting of a 175 dm3 pilot plant, in which a soil polluted with an average concentration of 20 mg kg−1 of 2,4-D (spread by simulating an accidental spill) undergoes electroremediation for two months with an electric field of 1.0 VDC cm−1 (between consecutive electrodes). Intensity, temperature, pH, moisture and pollutant concentration in electrolyte wells were daily monitored, and at the end of the experiments, an in-depth post-mortem analysis was carried out. In less than two months, the remediation technology attains a transport of more than 22% of the 2,4-D contained in the soil to the flushing fluids. However, the main mechanism for the removal of 2,4-D was found to be volatilization (which totalizes up to 57% of removal of 2,4-D). The significance of this mechanism was confirmed with the comparison of the results obtained in the remediation test with the results obtained in a reference test consisting of the monitoring of the dispersion of the 2,4-D pollutant in a soil which does no undergo electroremediation treatment. These results are of a great importance for future scaling-up of the technology.