Biological aereated filters for wastewater treatment: An interdisciplinary approach

Biological aerated filters (BAFs) are submerged media wastewater treatment reactors that combine both aerobic biological treatment and biomass solids separation by depth filtration. Biological aerated filters are used as a small footprint alternative to other aerobic processes and can operate at biochemical oxygen demand (BOD) loadings higher than those for trickling filters and activated sludge plants. Due to the combination of biological and physical treatment, the approaches used for describing BAFs have varied widely. As with other treatment processes for wastewater, different disciplines like physics, chemistry, biology and engineering have been used to describe and characterise BAF systems. Approaches from chemical engineering, physical processes and biological processes are discussed. By combining these approaches the biological aerated filter call be adequately described. Although it is necessary to obtain models that can take into account these approaches to BAFs, they are usually so complex that their use is limited.