There are several filters available for granular media filters. Some of them are mentioned below:

• Upflow filters
• Cell filters
• Automatic backwash filters
• Horizontal and radial filters
• Membrane filters

Type 1: Cell filters: A normal filter can be built to a maximum fixed size if the whole filter bed is to be backwash at the same time. If it is possible to backwash the filter bed in small sections then the filter shell can be larger. If the filter bed is divided by walls, then it is possible to backwash the bed in small sections. The filter bed should be divided just above the bed the filter floor so that we can place the hood over the section to get backwashed. The hood is placed on a Four-legged base of casks (gantry) that runs on rails along the top of the filter’s main sidewalls...