Media filter

A media filter is a type of filter that uses a bed of sand, peat, shredded tires, foam, crushed glass, geo-textile fabric, anthracite, crushed granite or other material to filter water for drinking, swimming pools, aquaculture, irrigation, stormwater management, oil and gas operations, and other applications. Each layer of media is designed to filter out specific types and sizes of particles, allowing for more efficient and effective removal of contaminants. One design brings the water in the top of a container through a "header" which distributes the water evenly. The filter "media" start with fine sand on the top and then becomes gradually coarser sand in a number of layers followed by gravel on the bottom, in gradually larger sizes. The top sand physically removes particles from the water. The job of the subsequent layers is to support the finer layer above and provide efficient drainage. As particles become trapped in the media, the differential pressure across the bed increases. Periodically, a backwash may be initiated to remove the solids trapped in the bed. During backwash, flow is directed in the opposite direction from normal flow. In multi-media filters, the layers in the media re-stratify due to density differences prior to resuming normal filtration. Multimedia filter can remove particles down to 10-25 microns. Multimedia filters use multiple layers of different filter media to achieve more effective and efficient filtration than single-media filters like sand filters. They can remove a wider range of particle sizes and types than single-media filters, resulting in more efficient filtration and longer filter life. They are effective at removing suspended solids, turbidity, and other contaminants from water. They can be used for a wide range of flow rates and particle sizes. They can be easily backwashed to clean the filter media and restore filtration efficiency. They require little to no electricity to operate. Multimedia filters have a higher capital cost compared to single-media filters like sand filters.