Filter

In wastewater treatment, a device or structure designed to hold back or remove solids and finely divided solids that will not settle. Filters designed to hold back solids include effluent filters on septic tanks, which prevent particulate solids from entering the drainfield. Filters designed to treat wastewater include various types of media filters including sand, textile, and peat, in which wastewater is discharged over the media for treatment by microorganisms as it trickles through the filter media. <