A screw screen is used to retain coarse dispersed impurities from wastewater with subsequent extraction. Screens are used in low-capacity treatment plants as part of a mechanical treatment assembly.
Mechanical treatment screw screen
The lower part of the screen, which is a perforated arc-shaped sieve, allows wastewater flows to pass through, while the coarse impurities contained in water are retained on the sieve. The impurities on the screen create a so-called "carpet" covering the inner surface of the screen and providing an additional filtering effect. Due to this "carpet" particles smaller than the filter screen are retained.
The retained on the sieve waste is transported to the upper part of the screen, where it is flushed and compacted on the built-in press.
The humidity of washed and compacted waste reaches 60% (dewatering degree – up to 35%).
Two versions of the screw screens are available:
- in a channel;
- in a stainless steel tank.
Screw screens operate in automatic mode without the participation of maintenance personnel and are fully integrated with the automated control system of any complexity.
Advantages of the wastewater treatment screw screen
- combined retention, washings and compaction of waste in one device;
- increased filtration efficiency due to the waste "carpet";
- a completely closed structure (if tank installed);
- corrosion resistance to aggressive media;
- waste washing function allows for the return of some organic matter to the wastewater.
- compact design.
