Screen Systems manufacture dewatering screens (filtration screens) and wedge wire screen filters. Wedge wire as a filter medium in upward flow clarifiers has proved to be an effective method for treating secondary effluents of varying quality. Used either as a ‘stand alone’ filter, or as a support for a pea gravel bed, stainless steel wedge wire has been installed very successfully in existing humus tanks and new installations. As a result, removing to suspended solids by flocculation and settlement.


Utilises the natural flow of water passing under a weir, through the wedge wire deck, which is usually mounted horizontally 300mm below the water level. The fine solids that carry through the narrowing zone of the wedge wire with the natural upward current, create a floc blanket on the face of the wedge wire deck. As a result this filters fine material not amenable to physical flocculation.

The majority of the remaining suspended solids caught within the narrowing zone of the wedge wire filter physically flocculate. Thereby increasing their settlement velocity and thus causing them to settle to the bottom of the tank.


A reduction in suspended solids of up to 50% will occur with a typical flow rate of 1M3/M2/Hr. In addition, the Biological Oxygen Demand (BOD) associated with the suspended solids removed will also be reduced by between 20% – 30%.

upward flow wedge wire clarifier

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The criteria for design of installation is based on maximum flow. Also to allow even flow distribution by equalisation of the hydraulic loading across the vessel, as well as being able to cope with any fluctuations in suspended solids wire concentration. In addition, each application is purpose designed in-house to suit the flow rates and characteristics of the feed individual location, and incorporates a support structure manufactured in galvanised mild steel for the stainless steel wedge wire deck.


In addition to its strength, the normal life has proved to be up to 20 years. A wedge wire upward flow clarifier requires the minimum of maintenance during its lifetime.

Backwashing is accomplished by firstly lowering the water level so that the wedge wire deck is exposed. Secondly, it then can be simply hosed down with an ordinary low pressure hose pipe, this ensures minimum downtime. In addition, The system is resistant to corrosion and unaffected by UV light degradation.

waste treatment



  • Purpose designed
  • Professionally installed
  • Inherent strength
  • Simple to clean
  • Minimum downtime
  • Unaffected by UV light degradation
  • Normal working life up to 20 years


Screen Systems recently completed a project for a welded wedge wire stainless steel dewatering screen. It was a welded wedge wire tubular filter with a 1mm aperture x 12S B profile. It was created using Stainless steel 304 and also had external support rods, 12 SB at approx. 12mm pitch plain cylinder.