Process for treating metal-containing acid water
AssigneeWater Research Commission
InventorsPeter Dale Rose, John Richard Duncan, Robert Paul Van Hille, Genevieve Ann Boshoff
Life of this patent
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Abstract
A process for treating metal-containing acid water comprises adding an alkaline aqueous component to metal-containing acid water, thereby to raise the pH of the acid water and to cause metals therein to precipitate. The precipitated metals are separated from the water in a separation stage. The water is then passed to a biological alkalinity generating stage wherein the alkalinity of the water is increased biologically. The alkaline aqueous component, which is added to the metal-containing acid water, is withdrawn from the alkalinity generating stage. Treated water is also withdrawn from the alkalinity generating stage.
Claims16
A process for treating metal-containing acid water, which process comprises
- adding an alkaline aqueous component comprising hydroxide and carbonate anions to metal-containing acid water, thereby to raise the pH of the acid water and to cause metals therein to precipitate;
- separating, in a separation stage, the precipitated metals from the water;
- passing the water from the separation stage to an algal growth vessel or pond containing algae and fitted with a mixing device in order to facilitate an even suspension of algal cells and to promote even distribution of light throughout algae-containing culture present in the pond, with the algal growth vessel or pond thus providing a biological alkalinity generating stage wherein the alkalinity of the water is increased biologically, and wherein algae-containing treated water is produced;
- withdrawing alkaline water from algal growth vessel or pond with this alkaline water being added, as the alkaline aqueous component, to the metal-containing acid water;
- withdrawing algae-containing treated water from the algal growth vessel or pond;
- separating algae from the withdrawn algae-containing treated water by passing the algae-containing treated water through at least one separation device;
- returning the separated algae to the algal growth vessel or pond;
- and
- withdrawing treated water from the separation device.
A process for treating metal-containing acid water, which process comprises
- adding an alkaline aqueous component to metal-containing acid water, thereby to raise the pH of the acid water and to cause metals therein to precipitate;
- separating, in a separation stage, the precipitated metals from the water;
- passing the water to a biological alkalinity generating stage wherein the alkalinity of the water is increased biologically and wherein dissolved sulphate anion-containing treated water is produced;
- withdrawing alkaline water from the alkalinity generating stage with this alkaline water being added, as the alkaline aqueous component, to the metal-containing acid water;
- withdrawing dissolved sulphate anion-containing treated water from the alkalinity generating stage;
- feeding the dissolved sulphate anion-containing treated water from the alkalinity generating stage into a facultative pond;
- feeding a carbon source into the facultative pond;
- subjecting the dissolved sulphate anion-containing treated water to biological sulphate reduction in the facultative pond, thereby to convert dissolved sulphate anions to sulphide anions which are also dissolved in the waste water;
- and
- withdrawing treated waste water from the facultative pond.
Dependencies are inferred from the claim text.