Rotating blade sand remover

DPR

CATEGORY SEWAGE
TYPOLOGY GRIT REMOVAL UNIT

WHEN TO USE IT

The rotating blade grit remover DPR type is installed on small and medium sized water and wastewater treatment plants to remove upstream, before the treatment processes, the grit in sewage in order to avoid operational problems due to any sediments and to any wearing the machines during the following treatments.

HOW IT IS MADE

The rotating blade grit remover type DPR is composed of: a couple of rotating blades designed to give a uniform and lamellar rotation to the water to be treated; a shaft on which the two blades are fitted; drive head for the control and rotation of the blade consisting of a cogwheel a pinion and a gear motor; a piping system for air supply and grit washing-suction; an air-lift suitable for lifting the water-grit mixture out of the tank; a blower which produces the air necessary for the operation of the air-lift; various components required for a corrent operation.

HOW DOES IT WORK

The water flow enters the tank tangentially and it is kept in rotation by the blade motion; 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 rate 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 grit sedimentation. The grit separated by the centrifugal force created by rotation, is gathered on the tank bottom and it is submitted to a first counter-current washing with air and pressurized water, in order to separate silt and organic materials. Then, by interrupting the washing process, the deposited grit is removed by the air-lift.