Biofilm process and IFAS system in wastewater technology

IFAS system in wastewater technology
IFAS system in wastewater technology

To treat wastewater with biofilm process solid surfaces (media) are inserted in the aeration tank of the WWTP. These surfaces help that microorganisms, which are in the wastewater, settle down. Furthermore the media prevent that microorganisms are flushed out of the basin.


Settled microorganisms feed on wastewater pollutants and reproduce. They form a kind of “shared apartment”, which continuing to spread also over several “floors”. Due to the several layers (“floors”) they stick well on media.


Biofilm is holding together by a gel-like protein and sugar mixture (extracellular polymeric substances = EPS). Thus, the microorganisms are fixed in the biofilm and can’t be flushed out. These characteristics offer the best conditions for microorganisms – including those with low division rates.


The heterogeneous structure of a biofilm allows the development of areas with different environmental conditions. As organisms with lower oxygen demand, for example, “live” in deeper layers, organisms with higher oxygen demand are settled down in upper layers. The result is that many varied microorganisms, which feed on different substances, are found in the biofilm. Together, the organisms are even able to filtrate and destroy persistent pollutants from wastewater.

The already mentioned structure of biofilm provides a further decisive advantage in wastewater treatment. The ramified biofilm structure supplies a large adsorption area. This supports the absorption of substance, which can’t be processed immediately. They are deposited in the biofilm and will be degraded gradually. Therefore loading peaks in wastewater can be controlled with the biofilm process as well.