text: Biofiltration is used to treat wastewater from a wide range of sources, with varying organic compositions and concentrations. Many examples of biofiltration applications are described in the literature. Bespoke biofilters have been developed and commercialized for the treatment of animal wastes, landfill leachates, dairy wastewater, domestic wastewater.
  This process is versatile as it can be adapted to small flows (< 1 m3/d), such as onsite sewage as well as to flows generated by a municipality (> 240 000 m3/d). For decentralized domestic wastewater production, such as for isolated dwellings, it has been demonstrated that there are important daily, weekly and yearly fluctuations of hydraulic and organic production rates related to modern families' lifestyle. In this context, a biofilter located after a septic tank constitutes a robust process able to sustain the variability observed without compromising the treatment performance.
  In anaerobic wastewater treatment facilities, biogas is fed through a bio-scrubber and “scrubbed” with activated sludge liquid from an aeration tank. [Removal of hydrogen sulfide from an anaerobic biogas using a bio-scrubber - ScienceDirect] Most commonly found in wastewater treatment is the trickling filter process (TFs) [Chaudhary, 2003]. Trickling filters are an aerobic treatment that uses microorganisms on attached medium to remove organic matter from wastewater.
  In primary wastewater treatment, biofiltration is used to control levels of biochemical oxygen, demand, chemical oxygen demand, and suspended solids. In tertiary treatment processes, biofiltration is used to control levels of organic carbon [ Carlson, 1998].