Combining Soil Vapor Extraction and Electrokinetics for the Removal of Hexachlorocyclohexanes from Soil

This paper focuses on the evaluation of the mobility of four hexachlorocyclohexane (HCH) isomers by soil vapor extraction (SVE) coupled with direct electrokinetic (EK) treatment without adding flushing fluids. SVE was found to be very efficient and remove nearly 70 % of the four HCH in the 15‐days of the tests. The application of electrokinetics produced the transport of HCH to the cathode by different electrochemical processes, which were satisfactorily modelled with a 1‐D transport equation. The increase in the electric field led to an increase in the transport of pollutants, although 15 days was found to be a very short time for an efficient transportation of the pollutants to the nearness of the cathode. Loss of water content in the vicinity of the cathode warns about the necessity of using electrokinetic flushing technologies instead of simple direct electrokinetics. Thus, results point out that direct electrokinetic treatment without adding flushing fluids produced low current intensities and ohmic heating that contributes negatively to the performance of the SVE process. No relevant differences were found among the removal of the four isomers, neither in SVE nor in EK processes. Soil vapor extraction (SVE) and electrokinetic treatment (EK) were used to evaluate gaseous flux generation and mobility of hexachlorocyclohexane isomers. SVE removed almost 70 % of the isomers in 15 days. The EK treatment without the addition of washing fluids produced low current intensities and ohmic heating that contributed negatively to the performance of the SVE process.