Mechanized screens

Step screen

Step screens can be used as fine material mechanical treatment equipment at wastewater treatment plants.

Step screens are intended for fine material treatment and extraction of fine and medium waste solids from industrial and domestic wastewater, with their subsequent unloading into a transporter or waste bin.

The screens are intended for use in wastewater with a pH of 6.5-8.5.

Screens of different dimensions are made of stainless steel AISI 304 or AISI 316 on demand. Dimensions of the screens are selected depending on wastewater solids and the dimensions of the channel.

Step screens consist of two steps from plate blocks (movable and fixed) that are made of stainless steel and mounted into the screens’ frames.

Movable and fixed plates are placed one between another. The movable plate block is connected to a geared motor through the connecting rod. This provides oscillating movement of the block.

Spacing between the plates is set to 5 mm (in the default setting) and is kept by polymer pads with a low friction factor. The screen is installed onto a special prop which is fastened to the floor on both sides of the channel. The screen is therefore fastened to the cross beam and it is possible to lift the screen over the channel for its maintenance.

A pneumatic sand removal device is installed on the screen bottom.

The solid waste layer is formed on the plate blocks that act as filtering mesh. The solids are moved periodically to the top edge of the frame via the plane-parallel circular motion of the movable plate block. The solids are then discharged onto the transporter or into waste bin. The screen's operation periodicity depends on the equipment automation scheme.

Due to the step screen operation principlem the contamination layer (which is formed on the working surface), creates an additional filtering effect. Because of this effect, the 5 mm gap spacing step screen extracts down to 3 mm sized particles.

  • Fine mechanical wastewater treatment is achieved due to the narrow filtering mesh spacing, as well as the contaminants layer formation on the screen's steps
  • The step screen is manufactured using stainless steel AISI304 or AISI316 (on customers demand) which makes equipment corrosion resistant
  • The screen is designed in order to block waste slipping through in wastewater containing rags, wool, etc.

Screen automation can be done according to different parameters:

  • Wastewater level difference upstream and downstream of the screen
  • Any customized program

Alarm systems of the normal operation indication, the emergency stops, 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 screen is supplied with a safety device to avoid damage to the screen’s parts. The safety device stops the screen operation when bulky waste ingress the filtering mesh, or when any other object blocks free plate movement. Light and sound alarms turn on simultaneously when the safety device is active. The screens, together with a conveyor, compacting press and slide gates, are included in a high-performance complex for mechanical wastewater treatment.

Equipping the control system with programmable modules makes it possible to integrate complex sub systems into one system with a common control center and remote dispatching.

Parameter Value
Openings, mm 5
Inclination angle, degree 50
Electric drive, pcs 1
Power, kW 2.2