Application of a vertical ‘electric sieve’ to mitigate and prevent salinization in coastal soil

Abstract

This study explored the applications of a vertical electrokinetic system (V-EK), which consists of multilayer electrodes positioned in shallow soil to form an 'electric sieve' to mitigate and prevent soil salinization caused by salts rising from saline groundwater in coastal areas. The experiments were conducted in column reactors in the laboratory. Compared to the control column, the level of ions in the surface soil was significantly reduced after the V-EK treatment, particularly for the column with voltages at 10 V and 20 V. At a voltage of 20 V, Na + was detected at a range of 0.06-0.08 mg g À1 in the surface soil; this is a >99% reduction compared to the controls. Similar efficacy was observed for Cl À in the V-EK column. The concentrations of Cl À were detected with a range of 0.01-0.02 mg g À1 and 0.02-0.06 mg g À1 at the surface soil with a voltage of 20 V and 10 V, respectively, compared to the Cl À concentrations at 0.84-2.70 mg g À1 in the control. After the application of the vertical 'electric sieve', the total salt content of surface soil could be controlled at a low value (<0.25‰) at voltages of 10 V and 20 V, compared to that in the control column (4.86‰). Finally, rising of salts from the artificial saline groundwater was effectively mitigated under voltages of 10 V and 20 V. Results from this work have demonstrated that the 'electric sieve' can effectively mitigate and prevent salts from rising in shallow groundwater to surface soil and reduce soil salinity.