WATER TREATMENT PROCESSES UTILIZING SEQUENTIAL ADDITION OF A BASE AND AN OXIDANT

摘要

When treating an aqueous stream containing metal ions, the pH is often raised to remove at least a portion of the metal ions. The presence of a multiplicity of metal ions with interfering chemistries and/or varying concentrations can make the pH rise difficult to predict for a given amount of base. Accordingly, water treatment processes can comprise: providing an acidic aqueous stream comprising one or more metal ions; adding a base to the aqueous stream and increasing its pH to a first pH value; after adding the base and increasing the pH, adding an alkaline source of hypochlorous acid to the aqueous stream and further increasing its pH to a second pH value, the second pH value being about 7 or above; and removing at least a portion of the metal ions from the aqueous stream after adding the base and the alkaline source of hypochlorous acid.