Degritting and degreasing suction bridge for rectangular basin

PDRA

CATEGORY SEWAGE
TYPOLOGY GRIT REMOVAL UNIT

WHEN TO USE IT

The degritting and degreasing suction bridge PDRA type is used on medium and large size wastewater treatment plants for the pre-treatment of degritting municpal pre-aeration and degreasing of sewage and/or industrial origin.

HOW IT IS MADE

The bridge essentially consists of: a mobile steel girder with walkway grating in galvanized steel; a couple of lateral trolleys in steel; a grit suction system consisting of a blower and air lift; a couple of gear-motors fitted on in correspondence of the bridge centre line (one for the transmission of the bridge translation motion and the other one for the scraper movement); set of components for grease separation; electric control panel; festoon power supply line; an aeration consisting of a side channel blower and air diffusers.

HOW IT WORKS

The bridge, during the upward run of its alternate motion, collects and removes any oily floating material by means of a surface scraper, while during the return run, sucks the grit collected on the tank bottom. The surface scraper is controlled by a cam mechanism that keeps it down during the working phase and up during the rest phase. In order to facilitate the separation of grease substances, the aeration system creates an oxygenation and flotation effect of the grease, making it easier for them to rise to the surface. The grease sucked up by the air-lift is pumped by the air-lift into a lateral channel running the full length of the tank. The protection against overloads is guaranteed by the use of electronic load limiting devices.