Description
The source water to be treated by a reverse osmosis (RO) system can sometimes contain elements that impede the RO’s optimum operation. A multimedia filter is ideal for reducing the level of suspended solids (turbidity) in water. Suspended solids are small particles, such as silt, clay, grit, organic matter and various micro-organisms. The filtration grade of a multimedia filter depends mainly on the filter media used and the flow speed through the filter. A typical multimedia filter contains three layers of media: anthracite, sand and gravel. In some situations, a multimedia filter provides sufficient treatment of the raw source water to make it suitable for immediate use as irrigation water.
The multimedia filter is cleaned automatically, using a number of valves to ‘backwash’ the system. Backwashing at a higher flow speed causes the solid particles to detach from the filter media. Because the space between the granules is expanded, the solid particles can be flushed out of the vessel.
