Selenium removal from contaminated waters

Gleason KJ, Yu J, Bunge AL, and Wright JD. Removal of selenium from contaminated waters using emulsion liquid membranes. In Bartsch RA, Way JD, eds. Chemical Separations with Liquid Membranes, Washington, DC American Chemical Society, ACS symposium series 642, 1996 342-360. 

Removal of Selenium from Contaminated Waters Using Emulsion Liquid Membranes... 

If the retort water is considered for domestic or irrigation uses, it would have to be treated to remove a number of contaminants. Of the major constituents in retort water, the NH4, HCOa", and organic compounds in the water clearly make it unsuitable for other uses (18). Of the trace constituents, the arsenic and selenium concentrations listed in Table IV are above the maximum permissible concentrations for drinking water (36). The boron concentration may make water unsuitable for irrigation (22). Other studies have found silver and lead concentrations in retort waters have exceeded the maximum permissible concentrations for drinking water (1,2,36). Numerous studies for the treatment of the retort water have been initiated (37). The objectives of these studies are usually to find a method to recover the ammonia and organic material from the water so that treatment costs will be lowered through by-product recovery. 

Kharaka Y. K., Ambates G., and Presser T. S. (1996) Removal of selenium from contaminated agricultural drainage water by nanofiltration membranes. Appl. Geochem. 11, 797-802. 

Activated alumina s role in a water filter is similar to that of carbon. When water comes into contact with it, it attracts and removes certain contaminants, notably arsenic, fluoride, selenium, and LEAD. When activated carbon and alumina are used together, the filter can be highly effective in removing lead, as well as a number of other contaminants. Success of lead removal varies from brand to brand. 

In this study, aiming to apply the system for removal of selenium from contaminated waste water, immobilization of selenium into the hydrate of calcium alumino-zincate has been studied. To further enhance the immobilization efficiency, adding calcium hydroxide to the present system, its effect on sorption of selenium by hydration of calcium alumino-zincate has been studied and stoichiometrically discussed. 

Sodium selenite has also been incorporated into styrene—butadiene mbber and used in a pellet form which results in the slow release of selenium into water. These pellets have been placed in lakes in Sweden which have fish contaminated with mercury owing to high levels of that element in the water. The selenium released by the pellets reacts with mercury to form insoluble, heavy mercury selenide which setties to the lake bottom and removes mercury from the ecosystem (126). 

Phytovolatilization involves the use of plants and plant-associated soil microbes to take up contaminants from the soil, transform them into volatile forms, and release them into the atmosphere (Lin, 2008). Phytovolatilization occurs as growing trees and other plants take up water and the organic and inorganic contaminants. Metalloids, such as selenium. As, and tin, can be methylated to volatile compounds or mercury that can be biologically transformed to elemental Hg. Phytovolatilization has been primarily used for the removal of mercury and selenium. 

Packed beds of activated alumina can be used to remove arsenic, fluoride, selenium, silica, and natural organic material (NOM) anions from water. The mechanism, which is one of exchange of contaminant anions for surface hydroxides on the alumina, is generally called adsorption, although ligand exchange is a more appropriate term for the highly specific surface reactions involved (2). 

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