Gravity Sand Filters
The gravity sand filter or rapid gravity filter are most commonly used in Municipal water purification plants worldwide. They use relatively coarse sand and other granular media to remove particles and impurities that have been trapped in a floc through the use of flocculation chemicals. Water and flocs flows through the filter medium under gravity and the flocculated material is trapped in the sand matrix.
These filters are typically designed as part of multi-stage treatment systems used by large municipalities.