Sewage treatment apparatus

Claim 1

SEWAGE TREATMENT APPARATUS COMPRISING: AN AERATING TANK ADAPTED TO CONTAIN SEWAGGE AT A NORMAL LIQUID LEVEL; A SETTLING TANK HAVING DOWNWARDLY CONVERGING SIDES AND LOCATED ADJACENT SAID AERATING TANK AND BEING IN FLUID COMMUNICATION THEREWITH; AN INFLUENT CONDUIT CONNECTED TO SAID AERATING TANK ADAPTED TO CONVEY SEWAGE THERETO; AN EFFLUENT CONDUIT CONNECTED TO SAID SETTLING TANK ADAPTED TO CONVEY SEWAGE THEREFROM; A DRAFT TUBE POSITIONED VERTICALLY IN SAID AERATING TANK AND EXTENDING UPWARDLY FROM A LOCATION SLIGHTLY BELOW THE ELEVATION OF SAID EFFLUENT CONDUIT, SAID DRAFT TUBE BEING IN OPEN COMMUNICATION WITH THE ATMOSPHERE OUTSIDE SAID AERATING TANK; A VERTICAL SHAFT EXTENDING THROUGH SAID DRAFT TUBE FROM A LOCATIN OUTSIDE SAID TANK TO A LOCATION ADJACENT THE BOTTOM OF SAID AERATING TANK; DRIVE MEANS OPERATIVELY CONNECTED TO SAID SHAFT ADAPTED TO ROTATE SAID SHAFT ABOUT ITS OWN AXIS; RADIAL IMPELLER MEANS FIXED TO SAID SHAFT AT THE LOWER END THEREOF; LONGITUDINAL BLADES FIXED TO SAID SHAFT AND EXTENDING FROM A LOCATION SLIGHTLY ABOVE THE LOWER END OF SAID DRAFT TUBE TO A POSITION ADJACENT SAID IMPELLER MEANS, THE RADIAL PROJECTION OF SAID IMPELLER MEANS BEING GREATER THAN THAT OF SAID BLADES; AND CONDUIT MEANS EXTENDING FROM THE BOTTOM INTERIOR OF SAID SETTLING TANK TO THE INTERIOR OF SAID DRAFT TUBE.