Water clarifying apparatus

In apparatus for clarifying raw water containing particulate contaminants where the apparatus includes (i) a cylindrical flotation tank, (ii) an inlet means to the flotation tank for raw water (iii) an inlet means for aerated water that also feeds the flotation tank, (iv) means for controlling the water level within the tank, (v) means for removing floated sludge from the surface of the water held in the tank which is formed by a flow of rising of air bubbles released from the aerated water in the tank which coalesce with particulate contaminants from the raw water and with a flocculation agent introduced into the flotation tank, and (vi) clarified water outlet means for directing the clarified water with contaminants thus removed from the flotation tank, wherein the improvement comprises,

• a set of conical, mutually spaced apart plates located in said flotation tank, said plates extending circumferentially over at least a majority of the tank, substantially the full circumferential distance about said tank except for a sector wherein said clarified water outlet means and floating sludge removal means are located, and each plate being generally flat in cross section and concentric with said tank with a generally flat surface to minimize turbulence in the water due to the rotation, and
• means for rotating said set of conical plates in unison with said sludge removal means and said clarified water outlet means within said flotation tank with said plates about the center of said tank so that said plates are oriented along their direction of rotation.