Bar Screen – Definition

Definition

An automatic bar screen is a machine designed to retain large solids and all types of debris contained in wastewater. It is a wastewater pre-treatment device that forms part of the liquid/solid separation process.

Wastewater pre-treatment

Pre-treatment consists of removing certain materials from wastewater, such as solid matter, grease, oils, or sand. This step is essential, because if pre-treatment is not carried out properly, the entire wastewater treatment process is affected.

The first stage of pre-treatment is known as screening. Wastewater containing solid materials passes through a screen, where the solids are trapped. Screening consists of manually or automatically removing these materials from the screen and collecting them in a container, such as a bin or waste hopper.

Manual screening consists of placing a screen across the flow, after which an operator manually collects the debris, for example using a simple rake or a screening basket that can be lifted manually by a cable. This is an archaic process that quickly reaches its limits as soon as the flow rate or the amount of debris increases. It is also an operation that can be hazardous for the person performing it.

The issues encountered

• Clogged lift pumps
• Blocked manual basket
• Saturated fine screens
• Clogged aeration grids
• Rags accumulating on the grease remover

The solution: the automatic bar screen

A device called an “automatic bar screen” is installed across the flow. Debris is still trapped by a screen, but this screen is cleaned automatically by the bar screen, which collects the solids and discharges them directly into a waste container or a conveying/compacting screw. This ensures optimal screening under all conditions, whether at low or high flow rates, and eliminates the need for personnel to perform this operation.

FB Procédés offers a complete range of automatic bar screens that fully meet all efficiency and quality requirements for optimal pre-treatment and screening:

• Effective pump protection
• Reduces the treatment load on the plant
• Takes no more space than a manual basket
• Not all debris is retained, unlike with manual baskets
• Little to no modification of the existing installation
• Discharge of screenings outside the station, directly into a waste bin
• Can be adapted to all types of installations
• Direct installation in the chamber, mounted against the vertical wall
• Bar screen maintenance performed exclusively outside the chamber