Eickelboom 021N filament types are commonly recognized to cause and contribute to sludge bulking in industrial and municipal wastewater treatment facilities.
The morphological characteristics of type 021N include irregular cell shape (commonly barrel-like), visible septa (cross walls), indentations at the septa, and diameter ranges of 1.6 to approximately 2.8 µm. Type 021N filaments commonly extend from the floc structure, often causing inter-floc filamentous bridging. Due to the large diameter (and often long length) of these filaments, proliferation of type 021N filament types commonly correlates to significantly high sludge volume index (SVI) values.
Type 021N filaments are represented by a fairly diverse group of
