Enhanced electrokinetic removal of problematic salts in arid and semi-arid areas

Abstract

Recently, soil salinization in arid regions has caused considerable damage to ecosystems, agricultural productivity, and civil engineering infrastructure and facilities. This threat has become one of the most hazardous environmental issues and is the main reason for land degradation, desertification, and reduced soil load-bearing capacities. Conventional techniques of mitigating soil salinization such as soil irrigation, soil substitution, planting salt-accumulating plants, and soil amendment are expensive, time-consuming, and ineffective. Thus, the remediation of salt-affected soils represents a new challenge in the mitigation of soil salinization in arid and semi-arid lands. In this work, the feasibility of an electrokinetic treatment that removes salts from saline soil was evaluated. Three experimental electrokinetic tests were conducted with a laboratory-made electrokinetic apparatus using deionized (DI) water as the working solution. The potential gradient was set to either 1.5, 2.0, or 2.4 V/cm. This range of values was chosen to ensure low energy consumption and to suppress heating, which has adverse effects on the treatment. An enhanced electrokinetic approach (EEA) was developed by investigating the effects of diiferent electrical applied voltages (EAVs) on the removal of salts. The results revealed that the salt concentration gradually decreased and the salt removal rate increased as the EAV was increased. The highest salt removal rate occurred with an EAV of 2.4 V/cm, which yielded removal efficiencies of 89% and 88% for calcium (Ca2+) and sulfate (SO42−) ions, respectively. This research shows that the proposed electrokinetic technique has the potential to highly efficiently remediate and reclaim problematic salt-affected soils in arid and semi-arid areas.