Channel screens are used at the beginning of the sewage treatment process to remove solid contaminants - screenings. They are installed in open flow channels and sometimes they are built into existing technological installations in municipal and industrial sewage treatment plants.
The operation of the channel screen is based on the flow of sewage through the perforated chamber of the inlet basket in which the screw conveyor moves. Screenings are retained in the basket while the liquid is drained through the basket perforation. The screw conveyor takes the screenings out of the basket and compresses them at the same time in order to minimize the water content and reduce the volume of the removed impurities.
The dimensions of the channel screens are adjusted to the size of the existing channel and the sewage flow. The screen performs preliminary work in the sewage treatment plant to separate solid pollutants before subjecting the sewage to further processes, including biological treatment. Thus, damage to the equipment in the treatment plant is prevented - pumps, aeration systems, etc. The size of the basket perforation clearance is individually selected for a given application and user needs. The screenings are transported externally by means of a screw conveyor equipped with a drainage zone. Screenings compacted in this way fall into containers and are taken to a communal waste dump. The operation of the sieve is fully automatic and does not require constant maintenance.
A type of channel screens are vertical screens. They have a similar design and perform similar tasks. They are installed in closed pumping station wells. Due to the often difficult service access the high content of fibers, rags, etc. in raw sewage, can cause blockage of the screen spiral. The use of these devices is limited and currently recommended only in specific situations.