Filamentous micro-organisms are bacteria,
fungi and algae whose cells do not become detached from one another following
cell division. Filaments comprised of a number of cells arise in this manner.
Sometimes the cells cannot detach as they are surrounded by a sheath (a sort of
About 80 different filamentous types, mainly bacteria, have been observed in activated sludge. Many filamentous types do not have a name, but a number (e.g. Type 0803 or IF-10), because their characteristics are not yet (completely) known. The abbreviation IF stands for Industrial Filament, viz. morphotypes mainly observed in industrial plants.
It is known nowadays that the filamentous populations in industrial WTPs differ significantly from those in domestic plants.
Filamentous micro-organisms are present in
just about every activated sludge. A massive increase in their number, however,
results in bulking of activated sludge. Some species can also cause scum
Below you will find some examples, click on the image button to view a higher resolution version.
|Meganema sp.||Type 021N|
|Type 1851 (Gram stained)|
|Type 0092 (Neisser stained)||Type 0961|