A "screen" is a type of control device used in various water and wastewater treatment processes to remove solids or other unwanted materials from water. Screens can be mechanical or manual and operate by passing water through a filtering surface that allows clean water to pass through but retains solids or debris. Screens are commonly used in wastewater treatment plants to remove large solids and debris that can damage or clog downstream equipment, such as pumps and membranes.
Some common types of screens used in water and wastewater treatment include:
Bar screens: These consist of vertical or inclined bars that allow water to flow through while trapping larger solids. Bar screens can be manually or mechanically cleaned.
Drum screens: These are cylindrical screens that rotate and remove solids by using brushes or spray nozzles.
Disc screens: These have multiple rotating discs that remove solids by a combination of filtration and backwashing.
Microscreens: These have fine mesh screens that remove smaller particles and solids from water.
Vibrating screens: These use high-frequency vibration to separate solids from liquids.
The type of screen used in a particular treatment process depends on factors such as the size and type of solids or debris present, the flow rate of the water, and the specific treatment goals.