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Review

A Mini Review of Pressure-Assisted Soil Electrokinetics Remediation for Contaminant Removal, Dewatering, and Soil Improvement

by
Ahmed Abou-Shady
1,2,* and
Heba El-Araby
3
1
Soil Physics and Chemistry Department, Water Resources and Desert Soils Division, Desert Research Center, El-Matariya, Cairo 4540031, Egypt
2
Laboratory of Water & Soil Chemistry, Water Resources and Desert Soils Division, Desert Research Center, El-Matariya, Cairo 4540031, Egypt
3
Independent Researcher, Kafr El Sheikh 33651, Egypt
*
Author to whom correspondence should be addressed.
Pollutants 2025, 5(4), 46; https://doi.org/10.3390/pollutants5040046 (registering DOI)
Submission received: 31 August 2025 / Revised: 13 November 2025 / Accepted: 24 November 2025 / Published: 1 December 2025
Browse Figures
Versions Notes

Abstract

In the last 32 years (1993–2024), the application of electric fields in soil management (soil electrokinetic, SEK) has undergone several stages of optimization and intensification. SEK has used both alternating current (AC) and direct current (DC). Numerous fields, including agriculture, sedimentation, phosphorus management in soil and sludge, fertilizer production, consolidation, reclaiming salt-affected soils, metal extraction, dewatering, remediation of contaminated soil (both organic, such as PFAS, and inorganic, such as heavy metals), and soil nutrient availability, have utilized the SEK concept. Numerous innovations were included in the SEK equipment’s design or combined with other biological, chemical, and physical processes. While we recently published a review article on soil electrokinetic/electroosmosis–vacuum systems for sustainable soil improvement and contaminant separation, the current study illustrates the role of applying the pressure-assisted soil electrokinetics technique and shows the effect of the opposite technique. Four points were used to show the function of pressure-assisted soil electrokinetics based on our analysis of six search engines from 1993 to 2024 (the previous 32 years), including (1) polluted soil remediation, (2) dewatering, (3) soil improvement, and (4) making soil ready for electrokinetic action by applying pressure. In contrast to other intensification methods (such as reverse polarity, pulsed electric field, and design change), we found very few publications addressing pressure-assisted soil electrokinetics throughout the literature search. Most investigations focused on the dewatering mechanism, despite the paucity of relevant papers. In contrast to conventional electrokinetic remediation, pump-assisted electrokinetic-flushing remediation increased the removal efficiencies of Cs+ and Co2+ from contaminated soil by 2% and 6%, respectively. Additionally, the results demonstrated that the pressured electro-osmotic dewatering approach outperformed the conventional electrokinetic techniques. At 40 kPa, hydraulic conductivity was reduced four-fold by electro-rehabilitation for alternative fuels, while at 100 kPa, it was reduced three-fold. It was also observed that pressure may be used to achieve the soil ready for electrokinetic action in order to guarantee proper operation. Since there are not many articles on the subject, future research may examine how pressure-assisted soil electrokinetics can be integrated with vacuum systems, reverse polarity mode, pulsed electric field mode, modifying the SEK design, overcoming the formation of cracks, etc.

1. Introduction

Soil electrokinetics is the technique by which two forms of electric fields—direct current (DC) and alternating current (AC)—are used in soil management. While AC refers to periodic reversal in circuits caused by changes in the current direction, DC refers to electrical charge flowing in one direction [1,2]. As Reuss discovered, a DC field through porous materials enabled water to move, which sparked the idea of applying an electric field to the soil around 1809, sparking the concept of electrokinetics [3]. When conducting field research in the 1930s and 1940s to investigate electroosmosis, Casagrande applied an electric field to real soil [3]. During the investigation into the phytoremediation of metal-polluted soils using tobacco and rapeseed, the impacts of electrical fields (AC and DC) were evident [4]. The AC and DC electrical fields were also utilized in additional research for electrokinetic remediation of soil using high-frequency and pulsed sinusoidal electric fields [5,6], electrodialytic remediation of copper mines [7], and pulsed variable electric field application [8].
It has been made to employ electrokinetic phenomena in the field during the last 60 or 70 years to resolve a number of practical and emerging problems, including agricultural management [9], sedimentation [10,11], phosphorus management in soil and sludge [12], fertilizer production [13,14], consolidation [15,16], reclaiming salt-affected soils [17], metals extraction [18,19], dewatering [20,21], remediation of contaminated soil (both organic, such as PFAS [22,23], and inorganic, such as heavy metals [24,25]), delivering nutrients to meet the bioremediation’s objective [26,27], and soil nutrient availability [28]. Electrokinetics consists of DC or AC application to the target material, such as soil [29,30], plants [31,32], sewage sludge [13,33], and wastewater [34,35]. Acar et al., Probstein and Hicks, and Acar and Alshawabkeh, all of whom developed guidelines and precepts in the early 1990s, popularized electrokinetics, a physicochemical method [36,37,38,39]. Further wastewater purification might be possible through electric field technologies coupled with other techniques such as Fenton oxidation and coagulation [40,41].
An overview of electrokinetic soil is shown in Figure 1 [42]. There are also processes that utilize electric fields to recover metal, such as electrolysis [43], electrodeposition [35], electrocoagulation [44,45], and electrodeionization [46,47]. Using the cathode and anode produces an electric field that triggers four processes in the target soil: electroosmosis, diffusion, electromigration, and electrophoresis [1,48]. The most effective ways to accomplish an experiment’s primary objective are electroosmosis and electromigration, according to some scholars [2,49]. Since SEK cannot distinguish between specific soil ions, the introduction of electric fields causes bulk movements [29]. The scientists’ efforts; however, led to the improvement of the separation, stabilization, and synergistic effects of elements (e.g., phosphorus) with SEK, through the use of additional compounds [50,51,52,53,54].
Our analysis of the electrokinetic process during the preceding thirty-two years showed that the idea of pressure-assisted soil electrokinetics was not well covered in the literature review across a number of different domains of interest. A recent review titled “Investigation of the properties and mechanism of activated sludge in acid-magnetic powder conditioning and vertical pressurized electro-dewatering (AMPED) process” [55] focused on investigating the properties and mechanisms of activated sludge rather than remediation or soil improvement. The potential applications of pressure-assisted soil electrokinetics in a number of relevant domains (such as contaminated soil remediation, dewatering, soil improvement, and making soil ready for electrokinetic action by applying pressure) are demonstrated in the present mini review.

2. Procedure for Choosing Published Works on Pressure-Assisted Soil Electrokinetics

We have focused on six search engines to gather published articles related to pressure-assisted soil electrokinetics, based on our prior experience gathering data for electrokinetic work based on our earlier review publications on soil electrokinetics (i.e., MDPI, Elsevier, The Royal Society of Chemistry, Springer, The American Chemical Society, and Taylor and Francis). We have recently released a number of articles pertaining to soil electrokinetic optimization and intensification, including controlling the pH of soil, catholyte, and anolyte [56], restore mercury-polluted soils [57], integrated soil electrokinetic/electroosmosis-vacuum systems [58], restoration of soil contaminated by per- and polyfluoroalkyl substances (PFAS) [22], preventing cracking during soil electrokinetic remediation [49], reverse polarity-based soil electrokinetic remediation [59], utilizing the approaching/movement electrodes [60], incorporating perforated electrodes, pipes, and nozzles [61], electrokinetics-based phosphorus management in soils and sewage sludge [12], pulsed electric fields application [62], process design modifications [1,48], and materials additives [2]. To make sure that a significant number of articles pertaining to the subject of pressure-assisted soil electrokinetics are gathered, search engine words such as “soil electrokinetics, pressure, dewatering, and remediation” were entered into these six search engines. Selecting the most relevant research topic for our assessment, “pressure-assisted soil electrokinetics,” included going through more than a thousand publications, paying close attention to the abstract and the materials and methods sections. We also looked at the list of published reviews cited in the aforementioned reviews in order to avoid duplication and ensure the uniqueness of the topic of the current mini review. As a result, we could not find any reviews that covered the specific technique of pressure-assisted soil electrokinetics in detail between 1993 and 2024.

3. Pressure-Assisted Soil Electrokinetics

3.1. Removal of Inorganic Pollutants

Cobalt and cesium-polluted soil was restored using pressure-assisted soil electrokinetics. Kim et al. examined the impact of flushing on the electrokinetic removal of cesium and cobalt from a soil surrounding a decommissioning site [63]. This study looked at two different electrokinetic designs (refer to Table 1 and Figure 2). The first was the conventional horizontal electrokinetic design, but in the second design, the conventional unit is connected to a pump (Figure 2). A pump-assisted electrokinetic-flushing remediation enhanced Co2+ and Cs+ removal efficiencies from polluted soil by 6% and 2%, respectively, when compared to traditional electrokinetic remediation. According to the following equation, a pump is required to increase in pressure transport of the washing solution in the soil pores [63]:
j = k 0 + k m ∇ ∅ + k h ∇ P C −   D τ 2 ∇ C
where the species’ molar flow per unit of pore area is denoted by j , k m in the electromigration coefficient, k 0 in the electroosmotic permeability, P is the pressure, k h is the hydraulic permeability, D is the diffusion coefficient, C is the molar concentration, and τ is the nondimensional tortuosity.
The impact of the pressure pump on pH disruption revealed unexpected outcomes at the end of the experiment. The average pH in a traditional electrokinetic cell was 2.5 (the anolyte contains 0.01 M acetic acid), whereas the average pH in a soil cell following the completion of electrokinetic assisted with a pump was 3.5. The average electrolyte flow rate increased to 96.5 mL/day when the pumping pressure system was installed, as opposed to 53.4 mL/day with the traditional unit [63]. Pumping pressure had a greater impact on the electrokinetic-flushing remediation during the first four days of the remediation; however, it declined after that. Because the negative complexions created by combining an electrolyte reagent with cobalt or cesium had moved to the anode. It was found that the removal efficiencies of cobalt and cesium close to the anode were decreased by around 10% [63]. Another research study that was performed for the same group likewise showed the previously described tendency (refer to Table 1) [64].
Han and Kim investigated the application of citric acid and sodium dodecyl sulfate in the enhanced electrokinetic removal of Pb from spiking kaolin [65]. In this investigation, a hydraulic head difference was used to pump sodium dodecyl sulfate and citric acid into the cathode reservoir on days seven and eight via the cathode effluent tube. Citric acid and sodium dodecyl sulfate solution were transported to x/L = 0.2 (normalized distance from cathode) with an applied injection pressure of 29.42 kPa. The results of the investigation showed that simultaneous injection of citric acid and sodium dodecyl sulfate solution with electrode polarity reversal decreased Pb precipitation and raised the removal rate in the cathode area by three times when compared to the unimproved approach [65]. The effectiveness of pressure-assisted electrokinetics was demonstrated by the three studies mentioned above that looked at its operation; however, our review of the 32-year period (1993–2024) found no additional pertinent publications that discussed the application of this technique for the electrokinetic removal of pollutant-containing soil.

3.2. Dewatering (Dryness Based on Electroosmotic Flow) Using Electrokinetics with the Pressure Assistance Technique

3.2.1. Case Studies

Using the electrokinetic design shown in Figure 3, the impact of cationic polyacrylamide (CPAM, low molecular weight (1 − 10) × 106) as a skeleton builder to promote electroosmotic flow was investigated to enhance electroosmotic flow in pressurized vertical electro-osmotic dewatering (Table 2) [66]. The investigations employed a cylinder-shaped electrokinetic reactor with a DC power source, a filter device, a pressure device, and a piston. The findings demonstrated that the sludge developed a homogeneous and porous structure with the addition of the ideal CPAM dosage, which offered water channels and improved electric transport, hence encouraging the breakdown of extracellular polymeric materials. According to the sludge moisture content study, the breakdown of extracellular polymeric compounds resulted in a greater release of bound water.
Based on the correlation between phys–chem behavior and dewaterability characterization, 1 mg/g TSS was suggested as the ideal CPAM dosage. Additionally, the re-flocculation of disintegrating sludge flocs enhanced the dewaterability and filtering of the sludge [66]. During the pressured electro-osmotic dewatering process, Feng et al. investigated the dynamic changes in the properties and constituents of the filtrate and activated sludge [67]. As indicated in Table 2, a constant pressure of 200, 400, or 600 kPa is supplied to the piston. Although a single pressure of 600 kPa was able to remove just a little amount of free and bound water from the activated sludge, the application of 50 V voltage during electrical compression caused both types of water to further decrease to 0.24 g−1 dry solid and 0.25 g−1 dry solid [67]. By using ultrahigh-pressure electro-dewatering, the pore-scale model and dewatering performance of municipal sludge were investigated (Table 2) [68]. Three dewatering modes were used in this study: “ultrahigh-pressure mechanical dewatering mode (UMDW), pressurized electro-dewatering (PEDW) with constant voltage mode (U-PEDW) and constant voltage gradient mode (G-PEDW)”. The results showed that middle-layer water may be forced to overcome capillary pressure by the application of an electric field, which results in G-PEDW removing more water than UMDW. G-PEDW and U-PEDW dewater municipal sludge to a moisture content of 28.41% and 27.33%, respectively. Additionally, compared to U-PEDW, G-PEDW used a lot less energy. Consequently, when compared to UMDW and U-PEDW modes, the G-PEDW mode, with the lowest moisture content and lowest energy usage, shows superior dewatering performance [68].

3.2.2. Facts and Conclusions

Several conclusions may be drawn from the pressure-assisted electrokinetic application that will be discussed in this paragraph. The electro-dewatering of sewage sludge at 0.6 MPa was significantly impacted by the duty cycle and pulsating frequency (refer to Table 2) [69]. An electro-dewatering technique that shows promise for the future is pulsating direct current-dewatering, which was shown to be more energy efficient than stable direct current-dewatering [69]. There are several advantages to using electrokinetic geosynthetics for dewatering, including the capacity to recover water throughout the process, cost and power reductions compared to similar dewatering methods, and the flexibility to retrofit [70]. The development of electrokinetic geosynthetics a few years ago produced a substance that, when used in electro-osmotic dewatering applications, did not experience the same corrosion problems as metal electrodes [71,72]. Electro-osmotic flow is enhanced when pH is controlled during the test. This might be because the zeta potential of the particle surface is highly influenced by the pH of the pore fluid [73]. Higher voltage electrokinetics were more effective for dewatering, as well as a lower ultrasonic frequency at higher powers. Reversing the electrokinetic voltage improved the results by making it easier for the H+ ions generated by electrolysis to escape. Dewatering efficiency increased by 10% when the cathode was positioned above the sludge sample and the anode below it [74]. Comparing experiments using raw sludge and raw sludge with added alkalinity to non-pressure experiments using the same types of sludge, pressure significantly reduced the amount of water in the final sludge cake during the electro-dewatering process [75]. Better control of the ohmic heating effect was made possible by applying a constant current first, followed by a constant voltage. While using a thin filter cloth greatly decreased energy usage when compared to a thicker one, the presence of filter cloth on electrodes had no obvious effect on the dewatering rate. It is beneficial to raise the final dry solids content by decreasing the initial cake thickness [76]. Changes in the amino acid composition and the compactness of protein secondary structures in extracellular polymeric materials may have an effect on the dewaterability of the sludge [77]. Partially bound water in activated sludge began to change into free water due to the coagulation and time-delayed magnetic field effects of magnetic microparticles (MMPs) along the magnetic micro-particle conditioning–drainage under gravity–mechanical compression–electrical compression stages [78]. Additionally, by serving as skeleton builders to create water passageways, MMP dosage greatly enhanced the dewatering effectiveness of bound water. Activated sludge filterability may be enhanced by MMPs’ ability to break down sludge cells and fractions of extracellular polymeric substances. This could lower the concentrations of byproduct-like material and tryptophan-like protein in loosely bound extracellular polymeric substances, as well as the ratio of protein/polysaccharide in the activated sludge matrix [78]. Increasing pressure, voltage, or time can improve the final cake solids, and applying more DC voltage can extract more water from a cake that has already been dewatered [79]. About several years ago, electrokinetic geosynthetics were created, creating a material that, when utilized in electro-osmotic dewatering applications, did not suffer from the same corrosion issues as metal electrodes [71,72].

3.2.3. Design of Electrokinetic Equipment

The majority of the pressure-assisted electrokinetic investigations for dewatering were based on the vertical design, as previously illustrated in Figure 3 [66]. The electrokinetic unit of this concept was made up of a cylinder-shaped reactor with a DC power source, a filter device, a pressure device, and a piston. The activated sludge was positioned between the anode and cathode, which were fixed at the top and bottom, respectively. As shown in Figure 4, the study by Citeau et al. [76] changed the electrokinetic unit’s vertical design to a horizontal one. Using compressed air, a steady 5 bar of pressure was delivered to the piston, with the potential to collect water from the vicinity of the anode and after the cathode. Additionally, Figure 2 also displays an additional SEK horizontal design.

3.3. Soil Improvement (Rehabilitation) via Pressure-Assisted Electrokinetic

Fuels and hydrocarbon derivatives are frequently stored in underground storage tanks. Usually, liners are placed beneath these tanks to stop overflow or leakage into groundwater. For waste fuels that are released to disposal locations (such as landfills or ponds), comparable protections are needed [80]. In order to repair fuel-damaged liners, Bani Baker et al. investigated the electrokinetic nondestructive in situ approach (refer to Table 3). Figure 5 shows the configuration of the column experiment for the technology of linear electro-silicatization. At the top and bottom of each column, electrodes made of perforated stainless-steel mesh were wired. Testing on liner rehabilitation was performed after the findings of the study on sand-bentonite liners at various pressures and liquids as permeates. A series of tests was conducted on liners that had been initially infiltrated with water and then with biofuels and ethanol. Using a pressurized tank, this experiment included a number of leaching column experiments that allowed liquids to be introduced into the liner while maintaining sufficient pressure inside the liner. Under pressure of 40 kPa, electro-rehabilitation for alternative fuels resulted in a four-fold reduction in hydraulic conductivity, and at 100 kPa, it was a three-fold reduction. The literature describes this technology in more detail [80].

3.4. Making Soil Ready for Electrokinetic Action by Applying Pressure

The pressure is used in a number of electrokinetic tests to ensure that the treated soil is in an appropriate state and to conduct the electrokinetic experiments appropriately. For instance, Lin et al. investigated how kaolinite near the anode improves cohesive strength during electroosmotic chemical treatment [81]. They applied an axial stress (i.e., vertical) of 15 kPa for about one day and then 30 kPa for three days in order to prepare test samples. The electroosmotic chemical treatment test was then conducted with the applied axial tension maintained at 30 kPa [81]. When applying the electrokinetic-Fenton technique to remediate soil polluted with phenanthrene, the treated soil was statically compacted into a cell using an air pressure of 150 kPa for seven days [82,83,84]. When using an electrode matrix and a rotating operating mode for in situ bioelectrokinetic remediation of phenol-contaminated soil, a soil specimen was compacted for 12 h at a pressure of 0.1 kg cm−2 [85]. Another research study employed the same conditions [86]. 117.6 kPa of pressure sterilization was applied to the soil for five minutes in order to study the processes of arsenic removal from soil using an electrokinetic technique in conjunction with an iron permeable reaction barrier [87]. The influence of electrokinetic remediation on microbial communities in pentachlorophenol-contaminated soil was investigated by statically compacting the soil in 100 g layers at a pressure of 50 kPa [88]. While conducting an investigation on enhanced electrokinetic remediation of heavy metals and PAHs-containing marine sediments, a final weight of 20 kg and a pressure of 0.64 kg cm−2 were achieved by compacting the soil with a starting load of 2 kg, followed by an additional 2 kg on each subsequent day [89]. In order to remediate Cu-polluted soil utilizing a unique anode configuration, solar-powered electrokinetics was performed. Over the course of four days, a surcharge load of 12.8 kg (or 5 kPa of pressure) was delivered to the soil specimen via the loading plate in five increments. After the initial surcharge load of 0.6 kg, the subsequent loads were 3 kg, 5 kg, 7.8 kg, and 12.8 kg [90]. As part of the electrokinetic remediation of metal-polluted marine sediments, the sediment sample was put in the central chamber and compacted by applying a static pressure of 40 g/cm2 for 24 h [91]. In order to examine the impact of polarity reversal on electrokinetic enhanced bioremediation of pyrene-contaminated soil, the wet soil was stacked and distributed inside the soil chamber at a pressure of 0.1 kg/cm [92]. All electrokinetic tests were carried out on identically consolidated offshore mud samples to a pressure of 207 kPa (30 psi) for 24 h at a voltage of 20 V [93]. A static pressure of 40 g/cm2 was applied for 24 h to compress the sediment sample, which was layered inside the electrokinetic cell [94]. A surcharge pressure of 22 kPa was applied to the soil via the loading plate following the placement of the soil sample in the main electrokinetic cell and the filling of the anode and cathode reservoirs with the appropriate fluids [95]. Using incremental pressure steps of 3–5 psi, the slurry was put into the electrokinetic cell and then consolidated to drain surplus water over the course of 24 h, reaching a total pressure of 30–40 psi [96].

4. Future Research on the Use of Pressure-Assisted Soil Electrokinetics Remediation

As we previously stated, our team is highly interested in demonstrating the soil electrokinetic optimization methods from several perspectives, such as controlling the pH of soil, catholyte, and anolyte [56], restore mercury-polluted soils [57], integrated soil electrokinetic/electroosmosis-vacuum systems [58], restoration of soil contaminated by per- and polyfluoroalkyl substances (PFAS) [22], preventing cracking during soil electrokinetic remediation [49], reverse polarity-based soil electrokinetic remediation [59], utilizing the approaching/movement electrodes [60], incorporating perforated electrodes, pipes, and nozzles [61], electrokinetics-based phosphorus management in soils and sewage sludge [12], pulsed electric fields application [62], process design modifications [1,48], and materials additives [2].
Only a few publications on pressure-assisted soil electrokinetics remediation are collected in this mini review. In the future, we propose combining the vacuum system with pressure-assisted soil electrokinetics remediation. It was possible to combine the vacuum system with the horizontal soil electrokinetic apparatus [97,98,99], vertical apparatus [100,101,102], mixed apparatus (vertical and horizontal) [103], in addition to the field application [104,105], and developing a vacuum system using vertical gradient electroosmotic dewatering [106]. The remediation of inorganic pollutants [98,107,108], and improving soil properties [99,101,109] were investigated using the integrated SEK/electroosmosis and vacuum. The literature contains detailed information about integrated soil electrokinetic/electroosmosis-vacuum systems for pollutants separation and sustained soil improvement [58].
There are numerous unique ways were lately reviewed for managing the pH of soil, catholyte, and anolyte for sustainable soil electrokinetics remediation, including the circulation of the electrolyte mixture approach [110,111,112], the separate circulation of the catholyte and anolyte [113,114,115], the use of approaching/moving electrode technique [116,117,118], application of pulsed electric fields [119,120,121], polarity reversal technique application [122,123,124], choosing the best electrokinetic design [16,23,125], etc., this may prove beneficial when combined with soil electrokinetics aided by pressure. The literature contains detailed information about managing the pH of soil, catholyte, and anolyte for sustainable soil electrokinetics remediation [56].
Utilizing the opposite polarity method may also prove beneficial when applying pressure-assisted soil electrokinetics. In the past, the reverse polarity method was applied in a number of areas, including remediating soil contaminated with organic pollutants [85,126,127], remediating soil contaminated with inorganic pollutants [128,129,130,131], removal of organic and inorganic pollutants simultaneously [86,132], integrated with phytoremediation [133,134,135], integrated with phytoremediation and bioremediation simultaneously [136,137,138], dewatering [139], and consolidation [140]. The literature contains detailed information on the integrated reverse polarity and soil electrokinetics [59].
In order to optimize the use of pressure-assisted soil electrokinetics, we may additionally include the use of approaching/movement electrodes for soil electrokinetic remediation optimization. Previous studies showed the applicability of using mechanisms of approaching/movement electrodes, including (1) the approaching/moving anode technique [118,141,142], approaching/moving cathode technique [143,144,145], electrodes placement/gap [146,147,148], and continuously reoriented/rotating, reciprocating, and rotational electric fields [85,149,150]. The literature contains detailed information on the use of approaching/movement electrodes for soil electrokinetic remediation optimization [60].
Future research may also concentrate on the specifics of examining the electroosmotic flow rates attained under various pressure scenarios, particular physical, chemical, and biological reactions take place during improved electro-osmotic dewatering when pressure is applied, how various ionic species in soil behave electrokinetically when exposed to pressure-assisted methods, details how soil type and texture affect the efficiency of pressure-assisted electrokinetic remediation, the formation of microfractures (cracks), etc.

5. Conclusions

The current review concentrated on the novel subject of soil electrokinetic optimization and intensification procedures, where solution injection and electroosmosis flow may be enhanced by the addition of a pressure unit. Four points in the present review, including polluted soil remediation, dewatering, soil improvement, and preparing soil for electrokinetic action through pressure, were investigated to illustrate the function of pressure-assisted soil electrokinetics based on our survey of six search engines conducted between 1993 and 2024 (the last 32 years). Although there were few relevant studies, the majority of studies concentrated on the dewatering mechanism. The current mini review’s findings demonstrated that pump-assisted electrokinetic-flushing remediation increased the removal efficiencies of Cs+ and Co2+ from contaminated soil by 2% and 6%, respectively, in comparison to traditional electrokinetic remediation. In contrast to the traditional methods, the pressured electro-osmotic dewatering method performed better. It was shown that electro-rehabilitation for alternative fuels reduced hydraulic conductivity four times at 40 kPa and three times at 100 kPa. Pressure may be used to prepare soil for electrokinetic experiments in order to ensure proper operation. Future studies might look at the use of vacuum systems, reverse polarity, pulsed electric field, altering the SEK design, preventing crack development, etc., because there are not many articles on the topic of pressure-assisted soil electrokinetics.

Author Contributions

Conceptualization, A.A.-S.; methodology, A.A.-S.; software, A.A.-S.; validation, A.A.-S.; formal analysis, A.A.-S.; investigation, A.A.-S. and H.E.-A.; resources, A.A.-S.; data curation, A.A.-S.; writing—original draft preparation, A.A.-S.; writing—review and editing, H.E.-A.; visualization, A.A.-S.; supervision, A.A.-S.; project administration, A.A.-S.; funding acquisition, A.A.-S. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by Science, Technology & Innovation Funding Authority (STIFA) known previously as Science and Technology and Development Fund (STDF), grant number 39369.

Data Availability Statement

Since this is a review article, no data were produced.

Acknowledgments

This work was supported by Science, Technology & Innovation Funding Authority (STIFA) known previously as Science and Technology and Development Fund (STDF), Grant No. 39369.

Conflicts of Interest

The authors declare no conflicts of interest.

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Figure 1. An illustration of the soil electrokinetic mechanics [1], re-drawn after Ifon et al. [42]. (Elsevier copyright—License Number 6101280169383).
Figure 1. An illustration of the soil electrokinetic mechanics [1], re-drawn after Ifon et al. [42]. (Elsevier copyright—License Number 6101280169383).
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Figure 2. An illustration of the pump pressure-assisted electrokinetic, after Kim et al. [63,64]. (Elsevier copyright—License Number 6100661020159).
Figure 2. An illustration of the pump pressure-assisted electrokinetic, after Kim et al. [63,64]. (Elsevier copyright—License Number 6100661020159).
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Figure 3. Schematic of pressurized vertical electro-osmotic dewatering (PVEOD), after (Cai et al.) [66]. (Elsevier copyright—License Number 6100661295264).
Figure 3. Schematic of pressurized vertical electro-osmotic dewatering (PVEOD), after (Cai et al.) [66]. (Elsevier copyright—License Number 6100661295264).
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Figure 4. Schematic representation of the (a) experimental setup and (b) the inner filter-press cell for four electrode arrangements: A: both electrodes and filter cake separated by filter cloth; B: both electrodes in direct contact with filter cake; C: the cathode in direct contact with filter cake and the anode separated by the filter cloth; D: the anode in direct contact with filter cake and the cathode separated by the filter cloth, after Citeau et al. [76]. (Elsevier copyright—License Number 6100670093120).
Figure 4. Schematic representation of the (a) experimental setup and (b) the inner filter-press cell for four electrode arrangements: A: both electrodes and filter cake separated by filter cloth; B: both electrodes in direct contact with filter cake; C: the cathode in direct contact with filter cake and the anode separated by the filter cloth; D: the anode in direct contact with filter cake and the cathode separated by the filter cloth, after Citeau et al. [76]. (Elsevier copyright—License Number 6100670093120).
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Figure 5. Setup of column experiment for the linear electro-silicatization technology, after Bani Baker et al. [80]. (Elsevier copyright—License Number 6100670271164).
Figure 5. Setup of column experiment for the linear electro-silicatization technology, after Bani Baker et al. [80]. (Elsevier copyright—License Number 6100670271164).
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Table 1. An overview of research on the application of electrokinetics improved by applying pressure to the electrolyte compartments for enhancing pollutant removal.
Table 1. An overview of research on the application of electrokinetics improved by applying pressure to the electrolyte compartments for enhancing pollutant removal.
No.The Type of Polluted Soil Initial Concentrations of ContaminantsSKE Equipment TypeComposition of the ElectrodeThe Pressure ConditionThe Voltage or Current AppliedExperimental PeriodThe Primary Findings from This Research
1Real soil with pH (5.9–6.9) [63].The concentrations of Co2+ and Cs+ were 238 mg/kg and 514 mg/kg.Horizontal design.Titanium.The anode chamber had a pump attached.20–50 mA.10–15 days.
  • Pumping pressure had a greater impact on the electrokinetic-flushing remediation during the first four days of the remediation, but it decreased after that.
  • Because the negative complex ions created by combining an electrolyte reagent with cobalt or cesium had moved to the anode, it was found that the removal efficiencies of cobalt and cesium close to the anode were decreased by around 10%.
2Real soil with pH (5.9–6.9) [64].Artificially contaminated with 0.01 M of Co2+ and Cs+.Horizontal design.Titanium.The anode chamber had a pump attached.2 V/cm.15 days.When compared to an electrokinetic remediation traditional design, the removal efficiencies of Cs+ and Co2+ were enhanced by 7.7% and 6.8%, respectively, by an electrokinetic-flushing remediation with pump pressure for 15 days.
3Kaolinite [65].Artificially contaminated with Pb (300 and 1780 mg/kg).Mixed design
(horizontal and vertical)		Carbon.A hydraulic head difference was used to pump sodium dodecyl sulfate and citric acid into the cathode reservoir on days seven and eight via the cathode effluent tube.
The applied injection pressure was 29.42 kPa.		12 V/cm.12 days.Simultaneous injection of citric acid and sodium dodecyl sulfate solution with electrode polarity reversal decreased Pb precipitation and raised the removal rate in the cathode area by three times when compared to the unimproved approach.
Table 2. An overview of research on the application of electrokinetics improved by applying pressure for dewatering.
Table 2. An overview of research on the application of electrokinetics improved by applying pressure for dewatering.
No.The Type of Polluted Soil SKE Equipment TypeComposition of the ElectrodeThe Pressure ConditionThe Voltage or Current AppliedExperimental PeriodThe Primary Findings from This Research
1Sludge with pH 7.02 [66].Vertical design.A titanium dish anode and a stainless-steel cathode.Sludge (100 g) was processed with a pressure of 2 MPa.19.3 V.15 min.The sludge developed a homogeneous and porous structure with the addition of the ideal CPAM dosage, which offered water channels and improved electric transport, hence encouraging the breakdown of extracellular polymeric materials.
2Activated sludge with pH 7.12 and EC 1.39 mS/cm [67].Vertical design.Titanium-coated mixed metal oxide.The piston was subjected to a steady pressure of 200, 400, or 600 kPa during the compression stage. 10, 30, and 50 V.2 h. Although a single pressure of 600 kPa was able to remove just a little amount of free and bound water from the activated sludge, the application of 50 V voltage during electrical compression caused both types of water to further decrease to 0.24 g−1 dry solid and 0.25 g−1 dry solid.
3Municipal sludge [68].Vertical design.Titanium alloy and graphite are used to make the anode and cathode plates.Three dewatering modes were used in this study: “ultrahigh-pressure mechanical dewatering mode (UMDW), pressurized electro-dewatering (PEDW) with constant voltage mode (U-PEDW) and constant voltage gradient mode (G-PEDW)”.
The applied pressure ranges were 2, 4, 6, and 8 MPa.		20, 30, 36, 40, 50, and 60 V.10, 20, 30, 40, 50, 60 min.When compared to UMDW and U-PEDW modes, the G-PEDW mode, with the lowest moisture content and lowest energy usage, shows superior dewatering performance.
4Sewage sludge with pH 7.31 and EC 1.54 mS/cm [69].Vertical design.-The cylinder was filled with 110 g of the sludge sample, which the anodic plate squeezed for 30 min at 0.6 MPa of pressure.10, 20, 36, 40, and 50 V.30 min.An electro-dewatering technique that shows promise for the future is pulsating direct current-dewatering, which was shown to be more energy efficient than stable direct current-dewatering.
Table 3. An overview of research on the application of electrokinetics improved by applying pressure for soil improvement.
Table 3. An overview of research on the application of electrokinetics improved by applying pressure for soil improvement.
No.The Type of Polluted Soil SKE Equipment TypeComposition of the ElectrodeThe Pressure ConditionThe Voltage or Current AppliedExperimental PeriodThe Primary Findings from This Research
1Sand-bentonite [80].Vertical design.Perforated stainless steel mesh electrodes.The tests were performed on liners infiltrated firstly with water, and then with alternative fuels such as biofuel and ethanol.
The test was conducted using water under a pressure of 40 kPa to completely percolate the liner.		0.5 V/cm.Refer to [80].Under pressure of 40 kPa, electro-rehabilitation for alternative fuels resulted in a four-fold reduction in hydraulic conductivity, and at 100 kPa, it was a three-fold reduction.
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Abou-Shady, A.; El-Araby, H. A Mini Review of Pressure-Assisted Soil Electrokinetics Remediation for Contaminant Removal, Dewatering, and Soil Improvement. Pollutants 2025, 5, 46. https://doi.org/10.3390/pollutants5040046

AMA Style

Abou-Shady A, El-Araby H. A Mini Review of Pressure-Assisted Soil Electrokinetics Remediation for Contaminant Removal, Dewatering, and Soil Improvement. Pollutants. 2025; 5(4):46. https://doi.org/10.3390/pollutants5040046

Chicago/Turabian Style

Abou-Shady, Ahmed, and Heba El-Araby. 2025. "A Mini Review of Pressure-Assisted Soil Electrokinetics Remediation for Contaminant Removal, Dewatering, and Soil Improvement" Pollutants 5, no. 4: 46. https://doi.org/10.3390/pollutants5040046

APA Style

Abou-Shady, A., & El-Araby, H. (2025). A Mini Review of Pressure-Assisted Soil Electrokinetics Remediation for Contaminant Removal, Dewatering, and Soil Improvement. Pollutants, 5(4), 46. https://doi.org/10.3390/pollutants5040046

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