Sand Filter

Within the scope of water treatment, filtration ist a mainly physical process for removal of suspended solids from liquids. The liquid to be filtrated flows through a filter medium, which results in the suspended solids being retained by this filter medium. A sand filter ist a vessel for filtration, with a filter bed consisting of silica sand serving as filter medium. With increasing service life, the differential pressure between the filter inlet and out increases for a given volume flow, as more solids are being retained within the filter medium. Eventually, the filter medium needs to be either backwashed or replaced. A sand filter requires periodic backwash, either with water only, or with both air and water. During backwash, waste water needs to be discharged.