Patent ID: 6203700
Filing Date: 2001-03-20
Classification: C02F

Abstract:
A process for treating metal-containing acid water, which process comprisesadding 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acid water;withdrawing algae-containing treated water from the algal growth vessel or pond;separating algae from the withdrawn algae-containing treated water by passing the algae-containing treated water through at least one separation device;returning the separated algae to the algal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; andwithdrawing treated water from the separation device.