Basic Biological Processes
Table 3.1 alphabetically lists the organisms which are frequently present during the
biological treatment. It should be remembered that those listed are important for the
treatment process: Therefore, pathogenic organisms which are present in treatment
plants, but which are not of any special importance for the treatment process itself,
are not included in the table.
Achromobacter
a type of bacteria, typically occurring in both biofilters and activated sludge plants.
Acinetobacter
one of the types of bacteria, responsible for the biological phosphorous removal I 6 I.
Alcaligenes
a type of bacteria, typically occurring in both biofilters and activated sludge plants
as well as in sludge digesters.
Bloodworm
red, 1-2 em long, very movable larvae. Can be found in biofilters and in sludge from
treatment plants. Is also known from very polluted streams I 41.
Chironomus
aquatic larvae of various species.
Crustacea
animals, occurring in very low-loaded activated sludge plants and ponds.
Daphnia
Crustacea, may occur in very low-loaded activated sludge plants and in ponds.
Desulfovibrio
bacteria capable of sulphate reduction, typically occurring in sludge digesters. By
excessive dominance, the produced hydrogen sulphide may cause odours and
toxic problems 121.
Filter flies
Psychodidae, a two-winged insect, 2-5 mm long, may occur in large numbers in lowloaded biofilters. The flies are of little importance for the functioning of the filter, but
they may be a nuisance to the environment.
Flavobacterium
a type of bacteria, typically occurring in biofilters and activated sludge plants as
well as in sludge digesters.
Geotrichum
a genus of fungi, occurring in both biofilters and activated sludge plants.
Micrococcus
a type of bacteria, occurring in biofilters and activated sludge plants.
Nitrobacter
bacteria, which oxidize nitrite to nitrate. Occur in low-loaded biological treatment
plants.
Nitrosomonas
bacteria, which oxidize ammonium to nitrite. Occur in low-loaded biological
treatment plants.
Nocardia
bacteria, producing foam in activated sludge plants.
Pseudomonas
a type of bacteria, occurring in biofilters, activated sludge plants, sludge digesters
and denitrifying plants.
Psychodidae
filter flies.
Rotifera
wheel animalcules, typical for low-loaded activated sludge plants. Indicator of an
extremely good biological treatment.
Sphaerotilus natans filamentous bacteria, which can influence settling negatively in activated sludge
plants. This unpleasant phenomenon is called bulking. The bacteria can also be
found in highly polluted streams 151.
Tubifex
3-4 em long red worm. Can be found in biofilters. Also known from highly polluted
streams 141.
Vorticella
are bell-shaped, attached Cilia tea, typically indicate a good biological treatment.
Free-swimming ciliates prey on free-swimming bacteria and thereby clean the water.
When the attached ciliates dominate, this is due to a shortage of free-swimming food
(bacteria) and hence is the indicator of a good treatment 121.
Zoogloea
bacteria, occurring in activated sludge plants as well as in biofilters. The bacterium
ramigera
easily flocculates, thanks to the production of a gelatinous slime, and thereby it is
important for slime formation as well as for the flocculation of the activated sludge.
Table 3.1
Organisms in biological treatment plants.
57
Table 3.1 alphabetically lists the organisms which are frequently present during the
biological treatment. It should be remembered that those listed are important for the
treatment process: Therefore, pathogenic organisms which are present in treatment
plants, but which are not of any special importance for the treatment process itself,
are not included in the table.
Achromobacter
a type of bacteria, typically occurring in both biofilters and activated sludge plants.
Acinetobacter
one of the types of bacteria, responsible for the biological phosphorous removal I 6 I.
Alcaligenes
a type of bacteria, typically occurring in both biofilters and activated sludge plants
as well as in sludge digesters.
Bloodworm
red, 1-2 em long, very movable larvae. Can be found in biofilters and in sludge from
treatment plants. Is also known from very polluted streams I 41.
Chironomus
aquatic larvae of various species.
Crustacea
animals, occurring in very low-loaded activated sludge plants and ponds.
Daphnia
Crustacea, may occur in very low-loaded activated sludge plants and in ponds.
Desulfovibrio
bacteria capable of sulphate reduction, typically occurring in sludge digesters. By
excessive dominance, the produced hydrogen sulphide may cause odours and
toxic problems 121.
Filter flies
Psychodidae, a two-winged insect, 2-5 mm long, may occur in large numbers in lowloaded biofilters. The flies are of little importance for the functioning of the filter, but
they may be a nuisance to the environment.
Flavobacterium
a type of bacteria, typically occurring in biofilters and activated sludge plants as
well as in sludge digesters.
Geotrichum
a genus of fungi, occurring in both biofilters and activated sludge plants.
Micrococcus
a type of bacteria, occurring in biofilters and activated sludge plants.
Nitrobacter
bacteria, which oxidize nitrite to nitrate. Occur in low-loaded biological treatment
plants.
Nitrosomonas
bacteria, which oxidize ammonium to nitrite. Occur in low-loaded biological
treatment plants.
Nocardia
bacteria, producing foam in activated sludge plants.
Pseudomonas
a type of bacteria, occurring in biofilters, activated sludge plants, sludge digesters
and denitrifying plants.
Psychodidae
filter flies.
Rotifera
wheel animalcules, typical for low-loaded activated sludge plants. Indicator of an
extremely good biological treatment.
Sphaerotilus natans filamentous bacteria, which can influence settling negatively in activated sludge
plants. This unpleasant phenomenon is called bulking. The bacteria can also be
found in highly polluted streams 151.
Tubifex
3-4 em long red worm. Can be found in biofilters. Also known from highly polluted
streams 141.
Vorticella
are bell-shaped, attached Cilia tea, typically indicate a good biological treatment.
Free-swimming ciliates prey on free-swimming bacteria and thereby clean the water.
When the attached ciliates dominate, this is due to a shortage of free-swimming food
(bacteria) and hence is the indicator of a good treatment 121.
Zoogloea
bacteria, occurring in activated sludge plants as well as in biofilters. The bacterium
ramigera
easily flocculates, thanks to the production of a gelatinous slime, and thereby it is
important for slime formation as well as for the flocculation of the activated sludge.
Table 3.1
Organisms in biological treatment plants.
57