An arch screen is a mechanically simple screening device used to capture solid waste in shallow water channels at wastewater treatment plants. An arch screen in wastewater treatment uses a fixed, curved screen surface combined with rotating cleaning arms to remove debris from the flow, offering a low-cost, easy-to-operate solution for applications where channel depth and complexity do not justify more elaborate screening equipment.
The defining advantages of the arch screen are its mechanical simplicity, ease of operation, and cost efficiency, making it a practical choice for shallow channel applications across municipal and industrial wastewater treatment.
What Is an Arch Screen?
An arch screen consists of a fixed, concave (arch-shaped) screen surface positioned across a shallow channel, combined with rotating arms that continuously clean the captured solids from the screen face. As an arch screen manufacturer and worldwide supplier, Vortex Engineering offers both perforated and bar screen options for the screen type, along with a wide range of dimension and stainless steel grade options.
The arch-shaped geometry of the screen surface is the defining structural feature that gives this equipment type its name, distinguishing it from flat bar screens or other channel screening configurations.
How Does an Arch Screen Work?
As wastewater flows through the channel, it passes through the arch-shaped screen, and solid waste is trapped on the concave surface. The curvature of the screen helps distribute the captured solids load across the screen face as flow continues.
Rotating arms mounted to traverse the curved screen surface continuously remove the captured waste, conveying it upward and discharging it at the top of the screen. This continuous mechanical cleaning action keeps the screen surface clear and maintains consistent hydraulic performance through the channel.
Why Use an Arch Screen?
The arch screen’s primary advantages stem directly from its mechanical simplicity:
Mechanical simplicity. With a straightforward fixed screen and rotating arm cleaning mechanism, the arch screen has fewer complex components than many other screening equipment types, reducing the potential points of mechanical failure.
Ease of operation. The simple operating principle requires minimal operator training and intervention for day-to-day operation.
Cost efficiency. Lower mechanical complexity generally translates to lower equipment and installation costs compared to more elaborate screening systems, making the arch screen an economical choice where its capabilities match the application requirements.
These advantages make the arch screen particularly well suited to shallow channel applications where its mechanical simplicity does not come at the expense of adequate screening performance.
Arch Screen vs Other Screening Equipment
| Arch Screen | Multi Rake Bar Screen | Static Screen | |
|---|---|---|---|
| Channel depth | Shallow | Any depth | Any depth, low flow |
| Cleaning mechanism | Rotating arms on curved surface | Multiple rake arms | None — self-cleaning by flow |
| Mechanical complexity | Low | Higher | Lowest |
| Best for | Shallow channels, moderate flow | High flow, wide/deep channels | Low flow applications |
The arch screen occupies a specific niche: shallow channel applications where a degree of mechanical cleaning is beneficial, but the full complexity of a multi rake system is not justified. For very low flow applications, a static screen with no moving parts may be an even simpler alternative; for higher flow or deeper channels, a multi rake bar screen is generally more appropriate.
Applications
Municipal wastewater treatment plants. Arch screens are used in smaller municipal plants or specific shallow channel locations within larger facilities, where mechanical simplicity and cost efficiency are priorities.
Industrial wastewater pre-treatment. Industrial facilities with shallow channel configurations use arch screens as a straightforward, economical screening solution ahead of further treatment processes.
Retrofits and channel-constrained installations. Where existing channel geometry is shallow and retrofitting a more complex screening system would be impractical, the arch screen’s compact, simple design offers a workable solution.
Materials and Construction
Vortex Engineering arch screens are manufactured from stainless steel throughout, selected for durability in the headworks screening environment.
Screen surface: Available in perforated plate or bar screen configurations, manufactured in stainless steel AISI 304 standard, with AISI 316 available for more aggressive environments.
Cleaning arms: Stainless steel construction, designed for continuous cyclic operation under load.
Drive system: Motorised drive mechanism sized to match the screen dimensions and expected solids loading.
Fasteners: Stainless steel A2 or A4 depending on the installation environment.
Frequently Asked Questions
An arch screen uses a fixed, curved screen surface with rotating cleaning arms and is generally suited to shallow channels and moderate flow conditions. A multi rake bar screen uses multiple independent rake arms along a flat bar rack and is suited to higher flow rates and deeper or wider channels. The choice depends on channel geometry and flow conditions.
Yes. Vortex Engineering offers both perforated and bar screen options for the screen surface type, allowing the arch screen to be configured for different solids capture requirements.
Arch screens are designed specifically for shallow water channels. For deeper channels, other screening equipment types such as multi rake bar screens or rotary drum screens are generally more appropriate.
Rotating arms continuously sweep across the curved screen surface, removing captured solids and conveying them upward for discharge at the top of the screen, providing continuous cleaning without manual intervention.
Arch screens are best suited to moderate flow conditions consistent with their shallow channel application. For higher flow rates, a multi rake bar screen or other higher-capacity screening equipment is generally more appropriate.
Vortex Engineering designs and manufactures Arch Screens as part of its complete Screening Equipment range and the full Wastewater Treatment Equipment lineup.
