Processes for water treatment

A process for treating water containing dissolved inorganic substances including metal ions, comprising the steps of

• (i) adding a first amount of neutralized bauxite refinery residue to said water in an amount sufficient to decrease the concentration of at least one inorganic substance in said water;
• and
• (ii) adding a second amount of neutralized bauxite refinery residue to said water in an amount sufficient to decrease the concentration of at least one of said inorganic substances to below a predetermined level;
• wherein in at least one of step (i) and step (ii), said neutralized bauxite refinery residue is added to said water together with one or more water treating additives;
• selected from the group consisting of alkali metal hydroxides, alkali metal carbonates, alkaline earth metal hydroxides, alkaline earth metal carbonates, alkaline earth metal oxides, calcium hypochlorite, sodium hypochlorite, sodium alum, ferrous sulfate, aluminum sulfate, soluble phosphates, phosphoric acid, hydrotalcite, zeolites, olivines, pyroxenes, barium chloride, silicic acid and salts thereof, meta silicic acid and salts thereof, and magadiite;
• wherein said neutralized bauxite refinery residue is red mud that has been treated with seawater, saline ground water or other water containing sufficient calcium and magnesium ions to react with substantially all of the hydroxide, carbonate, fluoride and oxalate ions present in the red mud, and for a time sufficient for the red mud to exhibit a reaction pH of less than 10.5, in a standard soil test when 1 part by weight of the neutralized red mud is mixed with 5 parts by weight of distilled or deionized water;
• and said process further includes the steps of (i)(a) separating or allowing to settle at least part of any insoluble material suspended in the water after step (i), and (ii)(a) separating or allowing to settle at least part of any insoluble material suspended in the water after step (ii).