CPC C02F 1/5209 (2013.01) [B01D 21/0042 (2013.01); B01D 21/01 (2013.01); B01D 21/08 (2013.01); B01D 21/245 (2013.01); B01D 21/2488 (2013.01); C02F 2305/12 (2013.01)] | 19 Claims |
1. A method of treating coagulated water containing solid matter in a single flocculation-decantation tank having a mixer in a bottom portion thereof, comprising:
directing the coagulated water into the flocculation-decantation tank;
directing a flocculant into the flocculation-decantation tank;
directing a ballast into the flocculation-decantation tank, wherein the ballast is fed directly into the single flocculation-decantation tank;
separating the solid matter from the water via a ballasted flocculation process by mixing with the mixer, the flocculant, the ballast and the coagulated water in the bottom portion of the tank to form ballasted floc that accumulates in a bottom portion of the flocculation-decantation tank as ballasted sludge;
the flocculation-decantation tank including lamellae disposed in a top portion of the tank above the mixer;
creating a non-stirred tranquil zone horizontally formed in the flocculation-decantation tank below the lamellae such that the tranquil zone extends horizontally across the flocculation-decantation tank between the mixer and the lamellae;
removing the ballasted sludge from the bottom portion of the flocculation-decantation tank by directing the ballasted sludge into a discharge line, injecting air into the discharge line and transferring the ballasted sludge via an air lift from the bottom portion of the tank to a ballasted sludge separator including a blade mixer;
in the ballasted sludge separator, subjecting the ballasted sludge to the blade mixer and disassociating the ballast from the ballasted sludge to yield separated ballast and separated sludge;
collecting the separated ballast in a decanter disposed over the tank and decanting the separated sludge from the decanter;
recycling the separated ballast back to the flocculation-decantation tank; and decanting a treated water from the flocculation-decantation tank such that both flocculation and decantation occurs in the same tank; and
wherein the ballasted flocculation process and the decanting of treated water takes place simultaneously in the single flocculation-decantation tank.
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