You Have Found The Satan...!
Characteristics : Straight or bent, thin filaments, 0.5 micron in diameter and 20 - 100 micron in length, found
radiating outward from the floc surface or free in the bulk solution. A sheath is present. No cell septa are observed;
however, empty spaces in the trichome are commonly observed. Gram negative and Neisser negative. No sulfur granules.
Filaments may occur in bundles, and attached growth is variable, ranging from rare to abundant. This filament can be
easily overlooked at 100 x observation.
Identification : Relatively short, non-motile filaments (20-100 µm). Straight or bent filaments with no branching.
Cell shape is concealed (0.5 µm). Filaments are found within the floc structure causing elevated SVI. Free in the bulk
solution in severe cases. The filament staining is Gram negative and Neisser negative. Usually easy to identify due to
its needle like appearance in a pin cushion. Intracellular granules not observed. No sulfur granules. Bundles of trichomes
and attached growth are common. Sheath is difficult to detect and no cell septa.
Similar Organisms : None.
Environment : This filament is usually found in environments where there low F/M, nutrient deficiency and low DO.
Usually overlooked due to its size at low magnification.
Control : F/M can be changed by increased sludge wasting, changing from complete mix to plug flow or use of a
selector. RAS chlorination should be definitely used if in the rapid growth phase. Increase DO and add nutrients if
this is the situation. Nutrient deficient wastes can be checked by effluent values of residual NH3 and
o-PO4 and should be supplemented if necessary.
Rank : H. hydrosis ranks 9th in number of predominance.
