A cost-effective, non-powered screen for the control of gross solids and floatables in combined sewer systems.

Designed to complement Hydro International’s wide range of CSO Screening products, the Hydro-Static® Screen provides screening better than 6mm in two directions. The Hydro-Static® Screen intercepts and retains floatables, aesthetically offensive material and gross solids over a wide range of flows. The collected material is then returned to the combined sewer after the storm event. An emergency overflow weir is incorporated into the screen should the peak design flow be exceeded.

The Hydro-Static® Screen is available as either an Up Flow Screen or a weir-mounted Through Flow Screen.

Hydro International’s patented flow-modifying components provide partial cleansing in the Up Flow configuration to keep maintenance to a minimum.

The Hydro-Static® Screen components are typically supplied in grade 304 stainless steel as standard. The mesh screen panels are coated in a non-stick polymer.

Applications

• CSO sites with infrequent spills.
• New and retrofit CSO facilities.
• Storm tank and pumping station overflows.

Advantages

• No moving parts or power requirement.
• High screen open area.
• Small footprint.
• Mesh screen panels are corrugated to increase flow-through capacity.
• Mesh screen panels are coated in a non-stick polymer.
• Provides screening better than 6 mm in two directions.
• Inexpensive screening solution.
• Patented flow modifying components provide partial cleansing in the Up Flow configuration reducing maintenance costs
• Ideal for smaller CSO sites.

During dry weather conditions the flow to the treatment works will pass underneath the screens in the dry weather flow channel.

In a storm event the inflow rate to the chamber will exceed the outflow rate causing water levels to rise in the chamber and spill through the screens.

The Hydro-Static^® Screen is mounted over the dry weather flow channel so that the flow passes up and through the screen during a storm event (red arrow).   Solids and floatables are trapped below the screen and returned to the sanitary continuation flow (brown arrrow).  Screen effluent is discharged to a receiving watercourse (blue arrow).

An emergency weir is incorporated into the screen should the peak design flow be exceeded.

Typical Design Loading Rate: 75 l/s/m².

Q. What is a Hydro-Static^® Screen?

The Hydro-Static^® Screen is a self-activating, non-powered screening system for the removal of material >6 mm in two directions. The screen is designed to intercept and retain aesthetically offensive material and gross solids at all states of flow up to the peak storm flow, with the material remaining in the foul sewer during and after the storm event. The screen can be configured as an Up Flow Screen or a weir-mounted Through Flow Screen.

Q. What advantages does the Hydro-Static^® Screen offer?

Patented flow modifying baffles are used on the up flow Hydro-Static^® Screen to encourage a re-circulation pattern above and below the screen panels. This flow pattern helps reduce any blinding effect when the screen is in operation. The up flow Hydro-Static^® Screen is also configured so that the top of the corrugated screen sits below the weir level. Once a storm has subsided this will allow a volume of water to backwash the screen panels helping to remove any debris that may be caught on the underside of the screen.
The Through Flow Hydro-Static^® Screen is offset from the vertical to encourage screening to drop away from the corrugated mesh one the storm has subsided.

Q. Is the Hydro-Static^® Screen manufactured in standard sizes?

Whilst we try to encourage the use of standard screen panels (1.215 x 0.641 m in plan) we can design Hydro-Static^® Screens specific to each application. We are usually able to offer a bespoke solution by cutting/extending our screen panels to suit without any increase in cost. This can be particularly useful for retrofit solutions.

Q. What are the loading rates/head loss figures for the Hydro-Static^® Screen?

The Hydro-Static^® Screen has undergone independent testing at the national CSO testing facility at Wigan Wastewater Treatment Works. Following on from this testing the recommended design loading range for the Hydro-Static^® Screen is 50-100 l/s/m² (nominal value = 75 l/s/m² ).
Head Loss figures for a 50% blinded screen at various loading rates are as follows:

Q. What is the weight of a screen panel?

The weight of a standard panel (1.215 x 0.641 m) is 20kg. This equates to 25.64 kg/m² of plan area and this value should be applied to non-standard panels.