Circular grit chamber DPR

The rotating blade sand remover is installed on small and medium treatment plants to comply with the sand removal requirements. It consists of an oil-bath gear motor to drive a rotating unit, which, in its turn, comprises a fifth wheel, a hollow shaft with a couple of blades and a piping system for air supply and sand washing-suction. The water flow enters the tank tangentially, is kept in rotation by the blade motion and once crossed the tank tangentially, it goes out in radial direction. The blades rotate in the same direction of the inlet flow speed; moreover the particular geometry of the blades allows the achievement of a constant speed of the fluid even though the flow changes; however, on request, for special applications, it is possible to replace the gear motor with a variable speed drive to modify the blade rotation according to specific requirements. In any case the blade rotation speed is such as to avoid the beginning of a turbulent condition that would interfere with the sand sedimentation. The sand, gathered on the tank bottom, is submitted to a first counter-current washing with air and pressurized water, in order to separate the organic material. Then washing is stopped and the sand is removed by means of the air lift and discharged in a sand classifier ES/ESA type (see herein after).