Modification of the properties of salt affected soils using electrochemical treatments

Abstract

In this project, an in situ soil treatment technique using the principles of electrokinetics was tested using laboratory experimental models in order to identify the potential of this approach in modifying and reinstating the physical properties of salt affected soils. Experiments were conducted in the laboratory using saline-sodic soils collected from two salt affected regions in central Victoria, Australia. Soil specimens were compacted in glass tanks to reproduce in situ density and in situ water content. Using mild steel electrodes inserted into the soil, a direct current was passed through the soil under a constant potential gradient of 0.5 V/cm for a period of 14 days. In separate experiments, distilled water and a saturated lime solution were introduced to the soil via the anode over this experimental period. It was observed that the soil dispersion, otherwise known as soil sodicity (measured as ESP-Exchangeable Sodium Percentage and SAR-Sodium Absorption Ratio) decreased by up to 90% in most regions of the soil between the electrodes. The compressive strength of the soil increased in excess of 100% with electrokinetic treatment alone while the lime-enhanced electrokinetic treatment led to an almost 200% strength increase. The liquid limit and plastic limit of the soil increased causing the plasticity index to decrease, indicating increases in soil compressive strength and workability. These results indicate the potential of this technique for improving the physical properties of salt affected soils both effectively and efficiently, and in particular gives hope for the remediation of salt affected land for infrastructure management and development.

Reclaiming Saline-Sodic Soils Using Electrochemical Processes: A Case Study From Sahl El-Tina Plain, Egypt

“…This technology uses an electric current in the treatment process to either mobilize or break down contaminants in soils or sediments (Niroumand et al 2012). Jayasekera and Hall (2007) observed that the soil dispersion, otherwise known as soil sodicity (measured as exchangeable sodium percentage and sodium adsorption ratio) decreased by up to 90% in most regions of the soil between the electrodes. Electrokinetic restoration has successfully been used to increase ionic mobility and separate pollutants from soil fields (Acar and Alshawabkeh 1993;Acar et al 1995;Zhou et al 2005;Altaee et al 2008;Ryu et al 2009;Park et al 2009;Kim et al 2009aKim et al , 2009bBaek et al 2009).…”

A Field Study on Electrokinetic Removal of Salts from Greenhouse Soil

“…In conclusion, the in situ EK technique is feasible for the restoration of saline greenhouse soils in or no cultivation and an appropriate strategy is necessary for more effective remediation. 최근에는 이러한 전기동력학 기술을 시설재배지 토양의 염류 제 거에 적용하려는 다양한 시도가 이루어지고 있다 [6][7][8][9][10][11]. Cho et al, [6,7]은 실험실 규모의 EK 실험을 통해 시설재배지 토양의 주요 염 류인 Na …”

A Review of Electrokinetic Treatment Technique for Improving the Engineering Characteristics of Low Permeable Problematic Soils

“…Electrokinetic (EK) remediation, also termed as electrochemical soil processing, electro-migration, electro-reclamation or electro-restoration, is an emerging technique which uses intensity direct current (DC) or a low electric potential difference to an array of electrodes placed in the soil, for removing organic, inorganic and heavy metal particles from low permeable soils, mud, sludge, slurries, sediments and groundwater by electric potential [14]. When a DC is applied to soil, it stimulates the migration of electricity, pore fluid, ions and fine particles across the soil towards the oppositely charged electrode, thus creating a combined effects of a chemical, hydraulic and electrical (CHE) gradients [15]. As this method has widely been used to remediate contaminated soils, with the application of electrical DC, contaminants in the aqueous phase or contaminants desorbed from the soil surface are transported towards electrodes depending on their charge.…”

“…There have been limited studies investigating the practical considerations for field implementations and the factors affecting EK processing [15]. The primary controlling factors are listed in Table 1.…”