Anaerobic Filter Reactor
Anaerobic filters are suitable for those wastewater that contains low content of suspended solids for instance in septic tanks after primary treatment and narrow cod/bod ratio. The bacteria in the filter are immobile and generally fix themselves to solid particles or to the reactor walls. Filter materials like rocks, cinder, plastic, or gravel provide additional surface area for bacteria to settle. The larger surface area for the bacterial growth helps in the quick digestion of the wastes. A good filter material provides a surface area of 90 to 300 meter square per meter cube reactor volume. Biological oxygen demand up to 70% to 90% is removed in a well operated anaerobic filter.
What is the Mechanism?
Anaerobic filters are reactors consisting of supporting material layer. On the surface of these material layers or bed fixation of microorganism and the development of biofilm takes place. Anaerobic filters can be applied not only for treating concentrated wastewater but also for those wastewaters that have low organic load. However, they function efficiently for diluted sewage. In case of concentrated sewage, the risks of blockage of the filter material increase with the concentration of suspended solids. Though due to this fact they can be used as main unit for treating wastewater. However, they are better suited for post-treatment. If they are preceded by a reactor that retains settled solids, they will work better.