The Internally-fed Rotary Screen is designed for versatility and can handle high flows and/or high solids. Typically, the IRS provides the driest solid versus the other www/PRESCREENs. In fact, this system can be used for thickening sludges containing 0.5% - 3% solids to 3% - 15%, depending on the type of sludge. The system operates by feeding the influent into a headbox, which extends 2/3 the length of the drum.The energy is dissipated as the flow is evenly distributed onto the sidewalls of the drum. In some sense, the IRS is like two sidehill screens facing each other. The spreading of this flow across the length of the screen assures proper water drainage.The thinner the layer of water, the less chance solids interfere with drainage.
Solids are retained on the screen surface as the liquid flows radially through the openings. Splash guards direct the liquid filtrate to a central drainage area, and the solids are transported axially, by flights, to the open end of the drum. The design of the flights in conjunction with the rotation causes these solids to turn over and release additional water. The rotation of the drum allows the entire screening surface to be continuously or intermittently washed by a fixed external spray bar fitted. The IRS has a cylindrical drum mounted horizontally on four shaft mounted trunnion wheels that are supported on pillow block bearings. The IRS screening element is a slotted wedgewire screen with openings ranging from 0.010 to 0.100 inches
