Electrokinetic soil remediation Research Papers (original) (raw)

The present work focused on evaluating the electrokinetic (EK) treatment of real contaminated sediments with toxic metals and polycyclic aromatic hydrocarbons (PAHs), using a big laboratory EK cell, periodic voltage and recently tested non-ionic surfactants. The results indicated that the "day on-night off" application mode of voltage, in conjunction with the selected solubilising agents, favoured the overall EK process. Arsenic, nickel and chromium exhibited the highest removal percentages, obtaining 83%, 67% and 63%, respectively, while zinc and lead attained 54% and 41% at the maximum. Furthermore, in the experiments where the non-ionic surfactants were introduced in the electrolyte chambers, there was a major uniformly removal of PAHs from the entire sediment across the EK cell, indicating the high solubilisation capacity of the enhancing agents. Essentially, transport and in some cases removal of PAHs (particularly from sections adjacent to the electrolyte compartments) also occurred in the unenhanced EK run, mainly due their negative charge, their potential weak bonds to the soil matrix and to the periodic application of voltage. Maximum removal was obtained by the use of Nonidet P40 where app. 1/3 (ca. 6498μg out of 20145μg) of the total initial amount of PAHs were removed from the cell.

- by John N Hahladakis
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- Surfactants, Sediments, Polycyclic aromatic hydrocarbons (PAHs), Toxic Metals
- by Hamdan Shadi
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- Electrokinetic soil remediation

The objective of this study is to evaluate the suitability and efficiency of electrokinetic
remediation treatment technique for the removal of crystal violet dye from clay soil. An electrokinetic
remediation cell (45cm length) equipped with a DC electric current with the maximum values of 30 V, stainless
steel electrodes used as anode and cathode were set up for two weeks operation. Sodium dihydrogen phosphate
(NaH2PO4) was used as the processing fluid (electrolyte) and was inserted to the electrode chamber to enhance
the electrical conductivity of the system and to increase the transportation rate of the contaminant from clay
soil. The effects of initial dye concentration (200 mg/kg, 400 mg/kg, 600 mg/kg, 800 mg/kg, 1000 mg/kg) and
applied voltage (30 V, 10 V), were investigated with time. Experimental results showed that, dye removal
efficiency were largely dependent on initial dye concentration. The removal efficiencies of the dye increase from
45.5% to 81.1% with increasing time at 30 V when the initial concentration of dye decrease from 1000 mg/kg to
200 mg/kg. The optimum efficiency of dye removal which was obtained at voltage of 30 V, initial concentration
of 200 mg/kg, contact time of 24 h was equal to 81.1%. The results showed that electrokinetic remediation
treatment technique has the potential and it is suitable for the removal of dye from clay soil

This research study is a part of research of soft clay and expansive clay stabilization with electrokinetic process. The movement of electricity in the clay caused to several phenomena including electrochemistry, electrophoresis, and elektroosmosis. In this study, the author discusses the phenomenon of cation exchange on expansive clays that occur during the electrokinetic process. Exchanger ions in this study is a calcium ions (Ca 2+) which is used as a stabilizer. Research carried out on 3 types of soft clay and expansive to get the behavior of cation exchange phenomenon is more valid and complete on clay soil. Electrokinetic process is done by using direct current (DC) with capacity 5 until 10 Volt. Observation of the phenomenon of cation exchange is done by measuring the concentration of calcium ion (Ca 2+) and compared to other ion concentration contained in clay for a certain period by using the AAS method (Atomic Absorption Spectrum). The results showed that an increase in the concentration of Ca 2+ ions in the clay during the electrokinetic process. Increased Ca 2+ offset by a reduction in other cations, such as sodium (Na +), and pottasium (K +) in the clay. The results could be used as a basic knowledge in developing electrokinetic processes as an alternative to expansive clay stabilization effort.

Electrokinetic remediation deserves particular attention in soil treatment due to its peculiar advantages, including the capability of treating fine and low permeability materials, and achieving consolidation, dewatering and removal of salts and inorganic contaminants like heavy metals in a single stage. In this study, the remediation of artificially lead (II) contaminated soil by electrokinetic process, coupled with Eggshell Inorganic Fraction Powder (EGGIF) permeable reactive barrier (PRB), was investigated. An electric field of 2 V –cm was applied and was used an EGGIF/soil ratio of 30 g-kg of contaminated soil for the preparation of the permeable reactive barrier (PRB) in each test. It was obtained high removal rates of lead in both experiments, especially near the cathode. In the normalized distance to cathode of 0.2 it was achieved a maximum removal rate of lead (II) of 68, 78 and 83% in initial lead (II) concentration of 500 mg-1, 200 mg-1 and 100 mg-1, respectively. EGGIF (Eggshell Inorganic Fraction) proved that can be used as permeable reactive barrier (PRB) since in all the performed tests were achieved adsorptions yields higher than 90%.

The atrazine behaviour in soils when submitted to an electric field was studied and the applicability of the electro- kinetic process in atrazine soil remediation was evaluated. Two polluted soils were used, respectively with and without atrazine residues, being the last one spiked. Four electrokinetic experiments were carried out at a laboratory scale. Determination of atrazine residues were performed by enzyme-linked immunosorbent assay (ELISA). The results show that the electrokinetic process is able to remove efficiently atrazine in soil solution, mainly towards the anode compart- ment: Estimations show that 30–50% of its initial amount is removed from the soil within the first 24 h. A one-dimen- sional model is developed for simulating the electrokinetic treatment of a saturated soil containing atrazine. The movement of atrazine is modelized taking into account the diffusion transport resulting from atrazine concentration gradients and the reversed electro-osmotic flow at acidic soil pH.

- by Helena I. Gomes
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- Contaminated Soils, Electrokinetic soil remediation

Electrokinetic process has emerged as an important tool for remediating heavy metal-contaminated soil. The process can concentrate heavy metals into smaller soil volume even in the absence of hydraulic flow. This makes it an attractive soil pre-treatment method before other remediation techniques are applied such that the chemical consumption in the latter stage can be reduced. The present study evaluates the feasibility of electrokinetic process in concentrating lead (Pb) and chromium (Cr) in a co-contaminated soil using different types of wetting agents, namely 0.01 M NaNO3, 0.1 M citric acid and 0.1 M EDTA. The data obtained showed that NaNO3 and citric acid resulted in poor Pb electromigration in this study. As for Cr migration, these agents were also found to give lower electromigration rate especially at low pH region as a result of Cr(VI) adsorption and possible reduction into Cr(III). In contrast, EDTA emerged as the best wetting agent in this study as it formed water-solubl...

- by Yee-Sern Ng
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- Environmental Engineering, Chemical Engineering, Environmental Science, Chemistry
- by Evangelos Gidarakos
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- Engineering, Surfactants, Hazardous Materials, Sediments
- by Felipe Hernández-Luis
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- Soils, Electrokinetic soil remediation, Buffering Capacity
- by Domingo Grandoso
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- Soils, Electrokinetic soil remediation, Buffering Capacity

This research is a series study of electrokinetic process that used as an alternative of stabilization effort of expansive clays. In particular, an observation of the behavioral changes of soil properties and also behavioral changes of soil swell that occur due to the phenomenon of cation exchange during the electrokinatic process were conducted. The cation used in this study was calcium ions (Ca 2+) which are derived from the solution of lime which also used as a stabilizer. Electrokinetic test was conducted by using 2A and 25V DC power. The tested samples in this study were taken from three different locations in Central Java, namely: Purwodadi, Boyolali and Klaten. The composition and concentration of ions in expansive clays was tested by using AAS (Atomic Absorption Spectrum) method. Behavioral of soil properties known the limits of Atterberg (ASTM 4318 and ASTM 427) from testing while the swelling behavior of soil by testing of swelling (ASTM 4546). The observations against the behavior of clay expansive was at the condition of a change in the concentration of sodium ions (Na +) in the soil during the electrokinetic process. The results showed that at conditions of the concentration of sodium ions (Na +) was smaller than the initial concentration, the behavior of the value of the liquid limit (LL), the index plastic (PI) and the nature of the development of clay expansive indicated a downward trend, while the behavior of the boundary value shrinkage of the soil showed an upward trend. The results of this research can be used as a baseline data to the development of electrokinetic as an alternative effort of stabilization expansive clays.

En el presente trabajo se hace uso de una técnica electrocinética para analizar, a través de las variaciones de la carga eléctrica (obtenida del los perfiles corriente – tiempo), los cambios en la capacidad de intercambio catiónico, en el contenido de carbono orgánico y en el contenido de cationes disponibles (Na+, K+, Mg2+ y Ca2+), en tres suelos diferentes de la isla de Tenerife sometidos a impacto térmico.

Agar matrix was artificially contaminated with caesium and subjected to rapid assessment of electrokinetic treatment on the basis of the 2D electrode configuration. The effect of caesium concentration on the process was investigated using different electrode configuration (i.e. rectangular, hexagonal and triangular). During treatment the in situ pH distribution, the current flow, and the potential distribution were monitored. At the end of the treatment, the caesium concentration distribution was measured. The results of these experiments showed that for caesium contamination, pH control is essential in order to create a suitable environment throughout the agar matrix to enable contaminant removal. It was found that the type of electrode configuration used to control the pH affected the rate of caesium accumulation. All of the electrode configurations tested was effective, but the highest caesium extraction was achieved when the hexagonal pattern was used to control the pH. After 72 h of treatment at 50 mA, the concentration of caesium decreased gradually from the second and first layer of agar matrix throughout the cell, suggesting that most of the caesium was concentrated on the cathode part.

- by Rudy Syah Putra
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- Electrokinetic soil remediation