Emptying sand traps in sewage purification installations - sediment rid completely of floating matter in bridge-mounted vessel

摘要

Sand traps in sewage farms, comprising deep narrow gulleys at the bottom of water courses, are cleared by pumping the mixture of suspended and precipitated matter with water, into a vessel arranged on a mobile bridge above the trap, where it is washed and dewatered by the action of agitators with lift, turn and deposit it repeatedly. The bridge, moving on runnersrs with guide rollers, carries a submersible pump delivering the sand mixt. via ducts tangentially into the vessel. This is formed by a section of a cylinder in which a worm conveyor runs in one direction to agitate the contents until the trap is emptied and then in the other to eject the sand through an outlet. Process gives a more thorough washing of the sand, a shorter waiting time for dewatering and a structure much lower in height.