Anionic contaminant removal

Chemical contaminants have widely varying affinities for sorbent surface and therefore the application of a selective sorbent seems to be an optimal method for contaminant removal. This justifies further research on active aluminium hydroxide (AAH), as a selective sorbent for specific anionic contaminant removal. The use of AAH as a sorbent involves both coagulation and ion-exchange mechanisms. 

Chemical pretreatment is often used to improve the performance of contaminant removal. The use of chemical flocculants is based on system efficiency, the specific DAF application and cost. Commonly used chemicals include trivalent metallic salts of iron, such as FeClj or FeSO or aluminum, such as AISO. Organic and inorganic polymers (cationic or anionic) are generally used to enhance the DAF process. 

In situ electrokinetic extraction (ISEE) is an in situ extraction technology that uses specialized lysimeter electrodes to remove anionic contamination from unsaturated soil. This technology is primarily used on soils with low permeabilities. During ISEE, a direct electric current is... 

Extract was prepared from the leaves and roots of two years old olive plants with water at room temperature. Internal standard as D-3-0-methylglucopyranose(MeGlu) was used and added In appropriate volume. Extraction was accomplished by shaking for 15 min and finally the suspension was centrifuged at 3000 rpm for 10 min. Before the injection the aqueous phase was filtered and passed on a cartridge OnGuard A (Dionex)to remove anion contaminants. 

In conclusion, the permeation behavior of the anionic contaminants undo study through SLMs containing either one of the amines investigated, confirms that the carrier of choice for the simultaneous removal of nitrates, Tc(VII) and Cr(VI) is the secondary amine Ambalite LA-2. 

Reconstruction (delamination) synthesis method is a promising technique based on the memory effect of LDH. This method eliminates the disadvantages of the coprecipitation methods because the CO anions are removed from the interlayer that is inevitably present in water in the form CO when the coprecipitation method is applied. In this way, the impurities that contaminate the interlayer during the synthesis can be removed allowing better control of the pore size distribution of the synthesized materials [7,21,22]. 

Lipoproteins may denature on heating and if present during pasteurization can result in the formation of haze or turbidity in the final product. This material was removed traditionally by filtration through asbestos (qv) sheets (6) however, health hazards associated with asbestos have led to its replacement by alternative filter materials (23,37,193). These media have been less effective than asbestos and further measures have been required to ensure the visual clarity of albumin products, eg, further filtration developments for Hpid removal (194), preferential denaturation of contaminants using in-process heat treatment, and anion-exchange chromatography (49). 

The potassium combines with the sulfur to form potassium sulfate, which condenses as a soHd primarily in the electrostatic precipitator (ESP) or baghouse. The recovered potassium sulfate is then deUvered to a seed regeneration unit where the ash and sulfur are removed, and the potassium, in a sulfur-free form such as formate or carbonate, is recycled to the MHD combustor. It is necessary also to remove anions such as Cf and E which reduce the electrical conductivity of the generator gas flow. These are present in the coal ash in very small and therefore relatively harmless concentrations. As the seed is recycled, however, the concentrations, particularly of CF, tend to build up and to become a serious contaminant unless removed. 

Electrodialysis. Electro dialysis processes transfer ions of dissolved salts across membranes, leaving purified water behind. Ion movement is induced by direct current electrical fields. A negative electrode (cathode) attracts cations, and a positive electrode (anode) attracts anions. Systems are compartmentalized in stacks by alternating cation and anion transfer membranes. Alternating compartments carry concentrated brine and purified permeate. Typically, 40—60% of dissolved ions are removed or rejected. Further improvement in water quaUty is obtained by staging (operation of stacks in series). ED processes do not remove particulate contaminants or weakly ionized contaminants, such as siUca. 

A further problem that may cause contamination of the treated MU water is anion leakage as a result of organic fouling. This significantly affects anion resins, preventing ion removal by ion exchange and thus reducing bed capacity. 

Biological activity can be used in two ways for the bioremediation of metal-contaminated soils to immobilize the contaminants in situ or to remove them permanently from the soil matrix, depending on the properties of the reduced elements. Chromium and uranium are typical candidates for in situ immobilization processes. The bioreduction of Cr(VI) and Ur(VI) transforms highly soluble ions such as CrO and UO + to insoluble solid compounds, such as Cr(OH)3 and U02. The selenate anions SeO are also reduced to insoluble elemental selenium Se°. Bioprecipitation of heavy metals, such as Pb, Cd, and Zn, in the form of sulfides, is another in situ immobilization option that exploits the metabolic activity of sulfate-reducing bacteria without altering the valence state of metals. The removal of contaminants from the soil matrix is the most appropriate remediation strategy when bioreduction results in species that are more soluble compared to the initial oxidized element. This is the case for As(V) and Pu(IV), which are transformed to the more soluble As(III) and Pu(III) forms. This treatment option presupposes an installation for the efficient recovery and treatment of the aqueous phase containing the solubilized contaminants. 

Ion exchange is a reversible interchange of ions between a liquid and a solid phase. The ions (contaminants) in a liquid wastestream and the ions on the surface of an ion-exchange resin are exchanged, purifying the wastestream while concentrating the waste constituent in the resin.22 24 Mixed resins are sometimes effective in removing both cations and anions. 

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