You Have Found The Satan...!
Characteristics : Filaments typically are 1.0 - 2.0 micron in width and 100 - 500 micron in length and taper
from a thicker basal region, often exhibiting an inconspicuous hold - fast, to a thinner apical region, often
terminating in loosely - attached gonidia. Trichomes are straight, smoothly - curved or sometimes slightly coiled and
are found extending from the floc surface. Cell shape ranges from ovoid to rectangular or barrel - shaped with clear
cell septa and indentations at septa. Gram negative and Neisser negative; may contain Neisser - positive granules.
Cells may stain slightly Gram positive when they contain sulfur granules. Spherical intracellular sulfur granules are
observed in - situ infrequently; response to the "S" test generally is positive. Rosettes are observed infrequently.
No attached growth. No sheath is present; however, a heavy cell wall (still showing cross septa) often remains after
cell lysis.
Identification : Relatively large , non-motile filaments (100->1000 µm). Straight or smoothly curved, sometimes
coiled filaments with no branching. Characteristic looping seen. Filaments taper from a thick basal region, and often
exhibit a holdfast to a thinner apical region, terminating in a loosely attached gonidia ( a distinctive rod-shaped cell
at the trichome end). Rosettes are observed infrequently. Rosettes are when many filaments radiate outward from a common
origin. The cell septa are very clear with indentations. Cells are very irregular, large and usually square but can vary
from disc, ovoid, rod or barrel shaped, sometimes even in the same filament (1.0-2.0 µm). This filament may look completely
different from different wastewater sample to sample. Different environments cause the changes in shape. Age of the
filament as well as the MLSS also impact the shape. When in a high growth phase, the filaments grow fast and the cell
shape is more consistent and regular. Filaments are found within the floc structure and the bulk solution when in rapid
growth stage. The filament staining is usually Gram negative and Neisser negative with Neisser positive granules. Can be
Gram positive when sulfur granules are present. Usually easy to identify due to its irregular shaped cells. There is no
sheath, although a heavy cell wall will remain after cell lysis with chlorination. There may be intracellular sulfur
granules and often responds to S-tests. Poly-ß-hydroxybutric acid (PHB) granules are frequently observed as dark
intracellular granules. No attached growth.
Similar Organisms : At least five other organisms can be mistaken for this filament because of its variable cell
shape, Thiothrix or Type 0041 especially.
Environment : This filament is usually found in environments where there is septic wastes, or wastes with sulfides
or organic wastes , N deficient wastes and low F/M when the waste is composed of simple sugars or organic acids. Grows
readily in food processing, wet corn milling, brewing and malting, fish processing petrochemicals and pulp and paper
mills.
Control : If the S test is positive, the cause is septic wastes or presence of sulfides and can be remedied by
pre-aeration or pre-chlorination. Nitrogen deficient wastes can be checked by effluent values of residual NH3
and should be supplemented. F/M can be changed by use of a selector. Chlorination should be definitely used if in the
rapid growth phase.
Rank : Type 021N ranks 3rd in number of predominance. (SVI values can exceed 500 mg / L). Rapid growth
of this filament can cause severe settling problems in only a few days.
