MEDIA FILTERS

Earlier filters used sand as the treatment media.  However, sand clogged easily and required frequent maintenance.  These filters use gravel as the media.  In each of the concrete filter boxes, there are 3 grades of gravel for a total depth of 40 inches of filtration material.

 Partially treated wastewater is applied to the filter surface in intermittent doses.  As it trickles through the gravel, it pulls oxygen into the spaces between the media particles.  Microorganisms (already present in the wastewater) attach themselves to the filter media and use the oxygen to digest and metabolize the wastewater pollutants (which they consider food).  The improved wastewater then collects in an under-drain and flows out to the distribution box.  By passing wastewater through the filter several times, microbes have more opportunities to eat and thereby remove more pollutants and odors than they would in a single pass.

  Media Filter Housing