Simultaneous removal of heavy metals and

Simultaneous removal of heavy metals and nitrate. In addition to denitrification, the above series of columns were also used for the removal of heavy metals. A decrease in the denitrification capacity of the column was used as an index of the critical heavy metal concentrations causing toxicity to the P. aeruginosa. The toxic effect of metals (lead, chromium, copper, cadmium and zinc) was examined in a separate study (unpublished data). Of these metals copper proved to have the highest toxicity as it fully prevented denitrification in a very short time at a concentration of 10 ppm. Regarding their toxic effect the next in order was lead, followed by cadmium, zinc, and chromium. 

Elektorowicz and Hakimipour (2001,2003a) presented a technology that permitted the simultaneous removal of heavy metals and PAHs from natural soil called Simultaneous Electrokinetic Removal of Inorganic and Organic Pollutants (SEKRIOP). This technology used EDTA for metal mobility and zwitterionic surfactants for hydrocarbon mobility. Furthermore, the application of cationic reactive membranes permitted capturing free metallic ions generated by electrokinetic phenomena before their precipitation in the cathode area. The capture of metal-EDTA complexes was done on anionic reactive membranes. 

SEKRIOP technology is capable of the simultaneous removal of heavy metals and organic pollutants using a multifunctional electrode system. 

Park HG, Kim TW, Chae MY, Yoo I-K (2007) Activated carbon-containing alginate adsorbent for the simultaneous removal of heavy metals and toxic organics. Process Biochem 42(10) 1371-1377... 

Miretzky, P., Saralegui, A., and Fernandez Cirelli, A., Aquatic macrophytes potential for the simultaneous removal of heavy metals (Buenos Aires, Argentina), Chemosphere, 57 (8), 997-1005, 2004. 

The simultaneous introduction of several conditioning liquids presents a challenge, particularly in clayey soils. Elektorowicz and Hakimipour (2003a) designed a system for the simultaneous desorption of heavy metals and PAHs, their simultaneous transport through the clayey soU, and removal. The system included the simultaneous utilization of a surfactant, a chelating agent, and special electrode supply/removal systems in combination with electrokinetic transport. 

The results showed that the application of the multifunctional method SEKRIOP to clayey soil permitted the simultaneous removal of heavy metals (Pb, Ni) and PAH (phenanthrene) in situ. The removal was observed in all cells including the control cell (Table 15.2). However, the removal percentage [normalized calculations expressed as the final concentration C (mg/kg) to the initial concentration Co (mg/ kg)] varied due to the different response of physicochemical processes, which were different in each cell. 

Alicia Fernandez Cirelli (water quality aquatic ecosystems aquatic humic substances heavy metal pollution use of macrophytes as biosorbents for simultaneous removal of heavy metals biotransfer of arsenic from water to the food chain). Director, Center for Transdisciphnary Studies on Water Resources, Faculty of Veterinary Sciences, University of Buenos Aires (UBA) National Scientific and Technical Research Council (CONICET), Buenos Aires... 

The modification of the sand surface allows the grains to simultaneously adsorb soluble heavy metals and remove particulate metals by filtration in a column packed with the media. Important factors to the performance of the adsorbent include pH of the solution to be treated, empty bed detention time (EBDT), and the presence of complexing agents, oil, surfactant, and biodegradable substances. 

C. C. Nesbitt and T. E. Davis, Removal of Heavy Metals from Metallurgical Effluents by the Simultaneous Precipitation and Flotation of Metal Sulfides Using Column Cells, in Extraction and Processing for the Treatment and Minimization of Wastes, J. Hager, B. Hansen, W. Imrie, J. Pusateri, and V. Ramachandran (eds.), TMS, Warrendale, PA, 1994, pp. 331-342. 

Barnes, L. J., Janssen, F. J., Sherren, J., Versteegh, J. H., Koch, R. O. and Scheeren, P. J. H. (1992). Simultaneous removal of microbial sulphate and heavy metals from wastewater. Trans. Inst. Mining Metall. 101, 183-190. 

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)... 

Maturi K, Reddy KR (2006). Simultaneous removal of organic compounds and heavy metals from soils by electrokinetic remediation with a modified cyclodextrin. Chemosphere 63(6) 1022-1031. 

Based on the laboratory experimental and field application results, electrokinetic remediation technology has been shown to be a promising method for simultaneously recovering multiple metal contaminants. However, the process is accompanied by limitations on the removal of several specific heavy metals. In this last section, the previous investigations, which focused on the removal of heavy metals, including Cr, As, and Hg, will be examined in more detail. Heavy metals have some reasonable properties, which should be considered more specifically ... 

Reddy and Karri (2008b) also reported research investigating Fenton-like oxidation coupled with EK remediation of low-permeabiUty soils contaminated with both heavy metals and PAHs. That study examined the simultaneous oxidation of organic contaminants and removal of heavy metals. Kaolin spiked with nickel and phenanthrene each at a concentration of 500mg/kg of dry soil to represent typical heavy metal and PAH contaminants found at contaminated sites. Four-week lab-scale EK... 

Enhancement solutions are either supphed in the electrode compartments and transported into the soil by electromigration or electroosmosis or mixed into the sod. The focuses for using enhancement solutions are (1) to mobilize different heavy metals at the same time, even though they are not mobile under same pH conditions as, e.g., Cu, Pb, and As [23], (11) to overcome a high acid-buffering capacity by mobilizing the heavy metals at neutral or alkaline conditions, e.g., the use of EDTA for removal of Pb from a calcareous soil [4], and (111) simultaneous removal of organic pollution and heavy metals, e.g., a combination of Tween 80 and EDTA for removal of lead and phenanthrene [3]. 

The conception of the three-dimensicMial electrode occurred almost simultaneously in France and England around 1966 as a necessity for precious metal recovery from dilute solutions occurring in industrial processes and for the removal of heavy metals from wastewaters. In this class of electrodes, the reaction stiU occurs at the liquid-solid interface, but the surface area is provided by the electrode volume. Porous or three-dimensional electrodes have been... 

Simultaneous removal of organic contaminants and heavy metals from kaolin using an upward electrokinetic soil remediation process. Journal of Hazardous... 

V. C. Gopalratnam, G. F. Bennett, and R. W. Peters, The simultaneous removal of oil and heavy metals from industrial wastewater by joint precipitation and air floatation. Environ. Prog. 7, 84-92 (1988). 

The process of SO2 removal on activated coke followed by a simultaneous reduction of NO with ammonia has been successfully applied in industry [176]. Mitsui Mining Process [177] (Table 12) and the Sumitomo Heavy Industry Process [178] are examples of the simultaneous desulphurization and NO removal with the application of moving beds of carbon adsorbents. Apart from the two above mentioned target gases, these processes also exhibit high removal efficiency for heavy metals and dioxins. Removal of NO on activated carbons can also be carried out using two separate processes. As NO2 can be easily removed from gas streams by water, low-temperature oxidation of NO to NO2 on the porous carbon surface is considered as feasible for the removal of NO without the ammonia addition [179]. 

For the simultaneous removal of organic compounds, these compounds are solubilized using different solubilizing agents (surfactants, cosolvents, and cyclo-dextrins). They are then transported and removed mainly by the electroosmosis process. It is essential to maintain all of the contaminants in soluble form and maintain electro-osmotic flow for the removal of both heavy metals and organic compounds. 

For some combinations of heavy metals, it is also necessary to use enhancement solutions to ensure the simultaneous removal of all pollutants (Ottosen et ai, 2003). Especially, the presence of As in the soil necessitate alternative solutions to the acidic front since As generally has low mobility under acidic conditions, whereas As is more mobile under alkaline conditions, where most heavy metals are not mobile (Le Hecho, TelUer, and Astruc, 1998 Ottosen et aL, 2000). Le Hecho, Tellier, and Astruc (1998) conducted laboratory experiments with spiked soils, where the pollutants were As and Cr. Successful remediation was obtained in the developing alkaline front combined with the injection of sodium hypochlorite. As was mobile in the alkaline environment, and Cr(III) was oxidized to Cr(VI) by hypochlorite and mobilized in the alkaline environment. In loamy sand polluted with Cu and As from wood preservation. As and Cu were mobile simultaneously after the addition of NH3 to the soil (Ottosen et a/., 2000). As was mobile due to the alkaline environment and Cu formed charged tetra-ammine complexes. For the simultaneous mobilization and electrochemical removal of Cu, Cr, and As, ammonium citrate has shown to be successful (Ottosen et al, 2003). 

The potential of electrokinetic remediation technology has been demonstrated for the remediation of mixed metal-contaminated soils, sediments, and groundwater over the past decade. Various enhancement schemes have been developed by the laboratory experimental and field applications, such as electrolyte conditioning and electrodialytic remediation. Despite such advances in the technology, it still has some limitations on the removal of mixed metal contaminants, including several specific heavy metals such as Cr, As, and Hg. Finding a simultaneously applicable process for the remediation of mixed heavy metals wUl require further study. 

Considering the effectiveness of the simultaneous heavy metals and PAH removal, it can be concluded that SEKRIOP might be used for an electrokinetic in situ remediation of mixed contaminated soils. The development of the above-described multifunctional method permits remediating the soils, particularly those characterized with low permeability. The results from the research can be applied to various municipal and industrial sites containing petroleum products and heavy metals. 

In a recent study, we proposed a new method (competitive adsorption method) for the removal of toxic heavy metal ions from acid-sensitive biomaterials, and applied it to the removal of cadmium from the MG of the scallop Patinopecten yessoensis [54]. In this method, a competitive adsorbent (IHA) is added to a weakly acidic solution containing MG to lower the cadmium concentration in the liquid phase. The lowering of the cadmium concentration in the liquid phase promotes the release of cadmium ions from MG, and the released cadmium ions are immediately adsorbed by IHA. In this manner the competitive adsorption method enables the simultaneous removal of cadmium from the scallop midgut and from the liquid phase under mild acidic conditions. 

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