Heavy metals removal electrokinetics

T0238 Electrokinetics, Inc., Electrokinetic Soil Cleaning T0239 Electro-Petroleum, Inc., Electrokinetic Treatment T0240 Electro-Pyrolysis, Inc., DC Graphite Arc Eurnace T0279 Environmental Research and Development, Inc., Neutral Process for Heavy-Metals Removal... 

Jensen JB, Kubes V, Kubal M. (1994). Electrokinetic remediation of sods polluted with heavy metals. Removal of zinc and copper using a new concept. Environmental Technology 15 1077-1082. 

Development of electrokinetic methods similar to those for heavy metal removal from soil is also carried on for other particulate materials as, e.g., municipal sohd waste incineration fly ash [11], bio ash [15], mine tailings [22], and harbor sediment [12]. 

Electrokinetic treatment can be used to remediate soils, sludges, and sediments contaminated with heavy metals and organic hydrocarbons. Electrokinetic treatment works well on clay-type soils with low hydraulic permeability, which are difficult to treat using other in sitn technologies. Electrokinetic permeabilities for aqueous systems in clays have been demonstrated to be up to 1000 times greater than normal hydraulic permeabilities, and some heavy metals have exhibited removal efficiencies of up to 100%. 

Pool Process electrokinetic remediation (Pool Process) is a patented, commercially available technology for the removal of heavy metals and other ionic contaminants. The technology uses a series of electrodes placed in contaminated media to recover ionic contaminants in situ or ex situ from soils, muds, groundwater, dredgings, and other materials. The Pool Process can also be used to enhance bioremediation of media contaminated with a combination of ionic and nonionic organic contaminants. 

ISOTRON Corporation s electrokinetic decontamination process is a patented, in situ process for the removal of contaminants from soil, groundwater, and porous concrete. The technology applies a low-intensity direct current (DC) across electrode pairs to facilitate electromigration and electro-osmosis of contaminants. The process works primarily on highly soluble ionized inorganics including alkah metals, chlorides, nitrates, and phosphates. Heavy metals such as lead, mercury, cadmium, and chromium have also responded favorably. 

Lynntech, Inc. s (Lynntech s), electrokinetic remediation of contaminated soil technology is an in situ soil decontamination method that uses an electric current to transport soil contaminants. According to Lynntech, this technology uses both direct current (DC) and alternating current (AC) electrokinetic techniques (dielectrophoresis) to decontaminate soil containing heavy metals and organic contaminants. A non homogeneous electric field is applied between electrodes positioned in the soil. The field induces electrokinetic processes that cause the controlled, horizontal, and/or vertical removal of contaminants from soils of variable hydraulic permeabilities and moisture contents. 

Pamukcu, S., and Wittle, J. K. (1992) Electrokinetic Removal of Selected Heavy Metals From SoilEnvironmental Progress, AIChE, 11(4), 241-250. 

Electrokinetics is an in situ remediation technology applicable to soil or soil-like material with low hydraulic conductivities (e.g., clay) contaminated with heavy metals, radionuclides, and selected organic pollutants. The technique has been used in the past in the oil recovery industry and to remove water from soils. 

Pamukcu and Wittle [133] investigated the feasibility of electrokinetic treatment at 30 V of different clay mixtures containing a number of heavy metals including Cd, Co, Ni, and Sr. The metal removal success ranged between 85-95% and appeared to depend on the soil matrix, the metal, and the pore fluid composition. At low initial metal concentrations, electroosmosis appeared to be the dominant mechanism for metal removal. At higher concentrations, electrolytic migration of the ionic species played a more dominant role. Of the three soil types tested, kaolinite had the highest electroosmotic efficiency. 

Kim, S. O., Moon, S. H., Kim, K. W., and Yun, S. T. (2002b). Pilot scale study of the ex-situ electrokinetic removal of heavy metals from municipal wastewater sludges. Water. Res. 36, 4765-4774. 

Reddy, K. R., Xu, C. Y., and Chinthamreddy, S. (2001). Assessment of electrokinetic removal of heavy metals from soils by sequential extraction. J. Hazard. Mater. 84(2-3), 279-296. 

Electrokinetic remediation involves passing a low level (mA cm ) DC electric current having potential difference a few volts through the soil, either in situ with electrodes placed into the soils, or in an external reactor. It has been shown that heavy metals such as zinc, copper, cadmium, chromium, lead, arsenic, mercury, nickel and iron can be efficiently removed from soils by electrokinetics. 

Electrochemical Remediation Heavy metals and other contaminants can be removed from the soil and groundwater with the help of electrokinetic phenomena (electroosmosis, electrophoresis, electrolysis). In electrochemical remediation processes, a continuous electrical field is generated with electrodes that are inserted into the contaminated soil (Shapiro etal. 1989 Ottosen etal. 1995 Hansen etal. 1997). Laboratory and pilot tests have been conducted, for example, with acetic acid as cleaning solution (Renaud 1990). With elec-... 

Numerous studies are reported on the electrokinetic removal of heavy metals from soils (Chapter 4). Many of these studies used ideal soils, often kaolinite, as a representative low-permeabiUty soil, which were spiked with a selected single cationic metal (such as lead and cadmium) in predetermined concentration. The spiked soil is loaded in a small-scale electrokinetic test setup and electric potential is applied. The transport and removal of the metal after specified test duration are determined. It is shown that cationic metals exist in soluble ionic form due to reduced pH near the anode regions and they are transported toward the cathode. However, when they reach near the cathode, they get sorbed or precipitated due to increased pH resulting from OH transport from the cathode. The actual removal from the soil is often negligible. 

Sequential approaches are developed where (a) anionic metals are removed first and then cationic metals when mixed metal contamination is present and (b) organic compounds are removed first followed by the removal of heavy metals when coexisting heavy metal and organic contaminants are found. For example, the simultaneous electrokinetic removal of inorganic and organic pollutants (SEKRIOP)... 

Pamukcu S, Wittle JK. (1992). Electrokinetic removal of selected heavy metals from soil. Environmental Progress ll(3) 241-250. 

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