Drum Screen outside-in is recommended for mechanical wastewater treatment in the meat processing industry with a high content of grease, wool and feathers. Drum screens with a triangle profile are intended for extraction of fine and medium waste solids from domestic and industrial wastewater with their subsequent mechanized unloading into a transporter or a waste bin.
The drum screens with triangle profiles are installed directly onto the wastewater supply pipeline.
The screens are intended for use in wastewater with a pH of 6.5-8.5.
Description of the Drum Screen outside-in
Screens are manufactured from stainless steel AISI 304 or AISI 316 on customer demand. The revolving cylindrical drum is made of a spiral, triangular profile and is driven by a gear motor. The drum is located inside the stainless steel casing.
The incoming wastewater is fed into a built in head dumping chamber in the front part of the casing. There are inlet wastewater flanges in the bottom of the head dumping chamber and outlet flanges in the top part for water drainage in the case of chamber overflow.
A drain connection for discharge of the chamber is also provided. There is a discharge tank to receive treated water and an outlet flange in the bottom part of the casing. A cover is provided at the top of the casing for visual process control, and to facilitate screen maintenance. The casing is mounted on supports of various lengths, depending on customer demand.
Operating principle of the Drum Screen outside-in
Wastewater flows into the head dumping chamber through the inlet flange. When the water level reaches the surface of the revolving cylindrical drum, it flows through its cells and runs down into the draining tank. Collected solids on the surface of the filtering drum are removed by a brass knife set at an acute angle close to the screen drum, and are dumped onto a transporter or a waste bin. Treated wastewater is drained through the outlet flange at the bottom of the screen. The filtering drum is washed during screen operation using treated water. In case of a high filtering mesh contamination, the water level rises in the head dumping chamber, and wastewater is drained through the outlet overflow flange located in the top of the chamber. Additional drum washing is performed by hot or cold water that is fed from pressure nozzles, and is designed for cleaning the filtering mesh from stubborn solids. The flushing water is supplied to the inside of the drum through the washing union at a pressure of 2-4 bar.
Advantages of the Drum Screen outside-in
- Screens fine material wastewater that contains hard to detect solids like feather, fur, wool
- Reliable and easy operation and construction
- Compact modular design is ideal for small wastewater treatment facilities
- All parts are manufactured from stainless steel
Automation of the Drum Screens outside-in
The screen switches on automatically when wastewater feed pumps starts. Various other automation options are also available. Alarm systems for the normal operation indication and emergency stops are provided.
It is possible to transfer equipment status data to a higher level automated process control system depending on the client’s requirements.