PIERO M. ARMENANTENJITTypical Heavy Metals Found inIndustrial WastewatersHeavy metals (as soluble ions) are common contaminantsof industrial wastewaters. Because of their toxicity theyare typically removed prior to wastewater discharge. Themost common heavy metal contaminants are:•Arsenic•Mercury•Barium•Nickel•Cadmium•Selenium•Chromium•Silver•Copper•Zinc•Lead
PIERO M. ARMENANTENJITPrecipitation of Heavy Metals•The heavy metal contents of wastewaters canbe effectively removed to acceptable levels byprecipitating the metal in an insoluble form.•Heavy metals are typically precipitated fromwastewater as:◊hydroxides◊sulfides or sometime sulfates◊carbonates•Metal co-precipitation during flocculation withiron or aluminum salts is also possible forsome metals (e.g., arsenic).
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