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Wastes Containing Metals Other Than Chromium VI

Liquid wastes containing metals other than chromium (VI) require direct precipitation. After precipitation, the metal precipitates are separated by gravity settling, clarification, and/or filtration. The sludges are subsequently dewatered before disposal. [Pg.191]

When the metals exist in the complexed form, it is necessary to break up the complexes and transform the metals to free form amenable to chemical precipitation. Metal complexes consist of a central metal ion surrounded by a group of other organic or inorganic ions or molecules. Examples of complexing molecules are ammonia, citrates, and ethylene diamine tetra acetic acid (EDTA). [Pg.191]

Wastes containing complexing molecules such as EDTA can be treated by a coprecipitation with ferrous sulfate, ferrous chloride or dithiocarbamate, which is used in conjunction with the regular precipitant, such as sodium-hydroxide. The treatment scheme requires two reaction vessels. Sulfide precipitation can be also used for complexed metals treatment. [Pg.191]

Wastes that do not contain complexed metals are precipitated by the regular precipitants such as lime, sodium hydroxide, or sodium carbonate. [Pg.191]

High influent concentrations do not adversely affect treatment since the residual metal concentrations depend on the solubilities of metal precipitates. However, high metal concentrations often indicate that the metals are complexed in solution and complexed metal compounds, if not dissociated, could have an adverse effect on treatment as mentioned above. [Pg.191]




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Chromium-containing wastes

Containing Wastes

Metal waste

Metallic Chromium

Metals chromium

Other metals

Waste containers

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