Hexagonal two dimensional electrokinetic systems for restoration of saline agricultural lands: A pilot study

This study was conducted to improve salt removal from saline soil in a pilot-scale electrokinetic (EK) system with the electrodes in a hexagonal configuration. The experiments were performed under a constant voltage gradient of 1 V/cm in an EK reactor (1 m × 1 m × 0.25 m) over 14 days. Chloride and nitrate were transported toward the anode by electromigration, and simultaneously moved toward the top layer from the bottom layer by pore-water evaporation. Nitrate removal was higher than chloride removal. Sulfate removal was uniform across all layers. Sulfate formed insoluble calcium sulfate, which reduced overall sulfate removal. The amount of exchangeable Mg was higher after treatment because the electrochemical reaction changed Mg fractionation. EK treatment resulted in the removal of approximately 30% of K and Ca from the system. Removal efficiency was enhanced because the hexagonal two-dimensional electrode configuration minimized the inactive area of the electric field, which was not the case in a one-dimensional rectangular system. However, the overall removal efficiency was not sufficiently high because of the relatively short operating time.

► Hexagonal two-dimensional electrode system was more effective than 1-dimensional electrode configuration.
► Nitrate, chloride and Mg were effectively removed, but sulfate, K and Ca were partially removed.
► Larger active area of electric field enhanced the removal of salts with less energy consumption.