An anaerobic upflow media filter is characterized by a long detention time and production of anaerobic effluent. It uses physical removal mechanisms which include flocculation, sedimentation, and absorption. Anaerobic digestion also occurs in the bed. They are generally filled with gravel media, but other non-degradable media types can also be used.
Following a septic tank, upflow media filters can remove additional TSS, BOD5, and organic nitrogen. They are generally not used for pathogen removal. Upflow media filters should be used in warm climates for best results. For increased nitrogen removal, aerobic treatment processes can be used in conjunction with an upflow media filter.