What is Sand Filter?
Definition of Sand Filter in Construction
A filtering system that uses sand as the filtering medium to separate dirt and contaminants from a fluid.
The fluid to be filtered is forced through a sand bed to allow the sand to separate the debris or contaminants from the fluid. By forcing the fluid through the sand bed, the water is taking with it the debris or contamination as it passes through the sand. The spaces between the sand particles catch the sedimentation that is designed to be removed from the fluid. The finer the sand, the finer the contaminants being removed.
Other types of filtering beds involve a special, very fine, earth product that has finer openings between the grains as the sand does. These smaller openings allow the smaller particles of contaminants to become clogged by the earth, thereby removing the contaminant. A sand filter is normally reversed to remove the contaminants from the sand. The principal is that if the sand caught the particle going forward, a reverse flow may actually dislodge the particle, and clean the sand. The backflow water is normally discarded due to the contaminants in the water from the backwash process. This process is performed for any type of filter bed separation of particles from a fluid.