Solar-powered electrokinetic remediation for the treatment of soil polluted with the herbicide 2,4-D

Abstract

In this work, the removal of a model pesticide (2,4-Dichlorophenoxyacetic acid, 2,4-D) using Electrokinetic Soil Flushing (EKSF) powered directly by DC current or by solar panels during a 15 days long treatment has been studied. Results show changes in operating conditions during the solar test, which can be clearly related to the day-night cycle, with a maximum solar irradiation intensity of 513 W m−2 at noon and an average daily charge supplied of 6.2 Ah d−1. The fluctuations in the intensity supplied to the electrochemical system lead to softer pH and conductivity profiles between anodic and cathodic wells in the case of photovoltaic (PV) powered system. After the 15 days long tests, the removal of 2,4-D reaches 90.2% and 73.6% in the electroremediation powered with DC power supply and solar panels, respectively. In this period,the total applied charge passed is 4.3 and 24.3 Ah kg−1 in both system, respectively. This means that the PV-powered electroremediation results in a much less efficient system, in which a much higher amount of charge is required to reach the same removal of pollutants in the soil. This fact may be related to the significantly lower EO flux observed during the operation of the PV-powered system.