Type 1701

This type is very rare in municipal sewage plants, but it is common in industrial plants with starch-rich wastewater, where it causes bulking sludge.

Morphology:

Filament position:	on the flakes or on edge of flake
Branching:	occasionally untrue branches
Movement:	none
Growth habit:	slightly curved
Aufwuchs:	partially present
Constrictions:	clearly visible
Sheath:	present
Transverse walls:	identifiable
Cell form:	rod-shaped; disc-shaped at the end of filament
Length of filaments:	< 200 µm
Filament diameter:	0.7 – 0.9 µm
Gram staining:	negative
Neisser staining:	negative
Special features:	if the septa are not identified, there is a risk of confusion with Type 1851 (low-load filament). If the cells are not identified, there is a possibility of confusion with Sphaerotilus natans.

Factors promoting growth:

high sludge load > 0.2 kg BSB5 / kg TS * d
wastewater with high concentration of carbohydrates (starch)
low concentrations of oxygen
full mixing of activation tank
temperature > 15 °C

Countermeasures:

reducing the sludge load der Schlammbelastung
increased concentration of oxygen
addition of ferrous precipitants (FERRACLAR CLASSIC, FERRAPLUS, FERRAL FD 1600, Contisolf, Contisolf Winter)

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