Screw screens are intended for the extraction of medium and fine waste solids from domestic and industrial wastewater, with their subsequent flushing, compacting and transporting into a waste bin.
It is recommended for fine mechanical wastewater treatment with a high fibrous content such as pulp and paper plants, food processing plants and textile industries.
It is possible to install the screw screen outdoors, but a shed and a screen heating device is required.
These screens are intended for use in wastewater with a pH of 6.5-8.5.
Screens are manufactured from stainless steel AISI 304 or AISI 316 on customer demand.
The screen is mounted in open channels or a tank with an incline of up to 45°. The slotted or perforated mesh is mounted in the bottom of the screen. Particles with sizes larger than the filtering mesh openings are collected on the mesh surface as wastewater flows through the mesh. The non-axial spiral with varied pitch screw is designated to remove waste from the filtering mesh, and transports material to the discharge zone on top of the screen. For better filtering mesh cleaning, the screw is equipped with a peripheral brush. The screen includes waste washing and compacting zones at the top of the screen before the discharge zone.
Particles that are collected on the filtering mesh of the screen are moved up along the barrel by a rotating spiral. At the same time, the mesh is thoroughly cleaned by peripheral brushes.
Waste compacting is achieved by the decreasing screw pitch. The organic contaminants are flushed from the waste by spray water from washing nozzles on the top of the barrel. Washing water and water pressed from the solid material is taken to the channel upstream of the screen by a pipeline. Washed and drained screenings are discharged into a waste bin at the discharge zone. The screen operation periodicity depends on the equipment automation scheme.
Screen automation can be done according to different parameters:
Alarm systems of the normal operation indication, the emergency stop, the wastewater top level in the channel and others are provided. It is possible to transfer equipment status data to a higher level automated process control system depending on the client’s requirements.The screw rotation can be reversed in order to eliminate jamming and congestion.