Sphaerotilus natans

Relatively long filament (100-1000μm), straight or slightly curved, with a diameter ranging from 1-1,8μm. Its cells are clearly observable in rod-shaped (1-1,8μm x 1,5-3,0μm) with rounded ends (sausage-shaped) or rectangular in shape when are packaged within a transparent and fair sheath . Displays false ramifications and growth of sessile bacteria is rarely observed. The color is negative Gram and Neisser. It doesn't present sulfur or polyphosphate beads, but PHB granules can be observed . This is an obligate aerobic filamentous, but survives in low dissolved oxygen and high F / M environments.

Type 0675

Filament relatively small (30-150μm long and 0,7-1,0μm diameter), motionless, straight or slightly curved, with no ramifications. Its cells are square (0,7-1,0μm) with clearly visible septa. It has sheath, which is usually covered by the growth of sessile bacteria. The color in most cases is Gram positive, but if it is covered with sessile growth may be presented as Gram variable, due to the difficult penetration of the dye. In industrial facilities, it is often seen as negative Gram. The Neisser coloring is negative and rarely presents positive Neisser sulfur. Neisser may have positive coverage in installations where there is a lack of nutrients. Does not present sulfur granules. this is associated with high sludge age, nutritional deficiency and / or low F / M.

Type 021N

Filament relatively large (100-> 1000μm long and 0,8-2,0μm diameter), motionless, straight or slightly curved or convoluted and without ramifications. It often causes the formation of bridges when extending from flake surface, but may also form rosettes. The cells are quite variable, and may be oval, rectangular, square or barrel-shaped and measure 1,0-2,0μm x 1,0-2,0μm. It has well defined septa with indentations. It is common to observe discoidal cells in the filament base (0,4-0,7μm x 1,0-2,0μm). Does not present sheath or growth of sessile bacteria and tricoma ends in a gonídia. It is Gram and negative Neisser and may have positive Neisser sulfur. It may contain sulfur granules, which makes it weak Gram positive. This grows in septic effluents or which contain large amount of sulfides and / or organic acids, lack of nutrients, low F / M and / or high concentrations of readily biodegradable substrates.

Type 1701

Relatively short filament (0,6-0,8μm of diameter and 10-100μm in length ), immobile, inclined or slightly curved, without ramifications. Its cells have a rod shape with a rounded end (sausage shaped) measuring 0,7-1,0μm x 1,0-2,0μm within a fairly transparent sheath. Generally presents abundant sessile growth, however, may be seen without sessile growth and projecting out of flake, which indicates rapid growth, not even allowing colonization. The filament is negative Gram and Neisser. Does not have sulfur granules, but is observed frequently presenting PHB granules. May be linked to bulking, indicating insufficiency of oxygenation in the middle.

Type 0041

Large filament (100-500μm long and 1,2-1,6μm of diameter) immobile, straight or slightly curved, unbranched and contains square cells (1.5-2 x 1,2-1,6μm, 0μm). It has sheath and septa are clearly visible. In industrial effluents grows at a fast pace, not allowing the colonization of the sheath by sessile bacteria. It is generally Gram positive, but if it is covered with sessile growth can appear as Gram variable, due to the difficult penetration of the dye. In industrial facilities, it is often seen as negative Gram. The Neisser coloring is negative and rarely presents positive Neisser beads. Neisser may have positive coverage in installations where there is a lack of nutrients. Absent sulfur granules. this filamentous is associated with high sludge age, nutritional deficiency and / or low F / M.

Thiothrix I

Relatively large filament (100-500μm long and 1,4-2,5μm of diameter), motionless, straight or slightly curved, with no ramifications. Bridges are formed when extending from the surface of a flake. The cells are rectangular (1,4-2,5μm x 3,0-5,0μm) with clearly visible septa and without indentations. It has sheath, but it is rarely observed the growth of sessile bacteria. The filament is negative Gram and Neisser and may have positive Neisser granules of sulfur and PHB. When there are many sulfur granules or when the sheath is very thick, preventing a good discolouration _ the filament may result in Gram positive. Also one can observe the formation of rosettes, presence of gonídias and a trichome of a diameter descending of the base into the apical region This filamentous is associated with bulking problems when the system presents septic sewage containing high levels of sulfides and organic acids (has a lot of sulfur granules), and deprivation of nutrients (presents PHB granules ). It can survive in anaerobic conditions since it is in the presence of sulfur sources. 

Thiothrix II

Medium-sized filament (50-200μm long - 0,7-1,4μm of diameter), motionless, straight or slightly curved, with no ramifications, extending from flake surface. The cells are rectangular (0,7-1,4μm x 1,0-2,0μm) with clearly visible cellular septum, but without indentations. The sheath is generally difficult to be detected and rarely seen the growth of sessile bacteria. It is Gram and Neisser negative, may contain sulfur granules of PHB and positive Neisser. Filament usually narrows from base to apex and may form rosettes or gonídias. This filamentous bacterium is an indicative of the presence of septic sewage, lack of nutrients or presence of high concentration of rapidly biodegradable carbonated substrates.

Type 0914

Relatively small filament _ (50-200μm long and 0,6-1,2μm of diameter), motionless, straight or slightly curved, with no ramifications. The cells are square (0.7 x 1,0μm) and has no sheath. It may be protruding out of the flake or free in solution. It may contain granules of sulfur and PHB. The color of the filament is Gram negative or Gram positive and negative when there are Neisser sulfur granules with positive Neisser granules. Usually found in environments with septic waste and sulfides, and low F / M with simple sugars and organic acids.

Beggiatoa spp.

Relatively large filament (100-500μm long and 1,2-3,0μm diameter), mobile, straight and without ramifications. The cells are rectangular (1-3 x 4-8μm). The filaments are found free in the solution and have a sliding movement and bending, which makes it easy to identify. The coloration is Gram positive but may be Gram negative if any sulfur granules are found. It is negative Neisser, with positive Neisser granules being observed frequently. May contain sulfur granules, making no visible cell septa. It doesn't present sheath or sessile growth. This filament is usually found in environments where there are septic waste, sulfides and large amounts of reduced sulfur compounds.

Type 1851

Medium-sized filament (100-300μm long and 0,5-0,7μm of diameter), motionless, straight or bent without ramifications.The cells are rectangular (0.8 x 1,5-2,5μm) and there are no defined septa. They are usually observed as beams in the solution.The Gram coloration is negative, but may be Gram positive and negative Neisser with poor hue.It's Generally easy to identify due to the attached sessile growth, which is perpendicular to the surface of the filament.It has no sulfur granules and the sheath is present, but it is sometimes difficult to observe. This filament is usually found in environments where there is low F / M and BOD and high sludge age.

Type 0803

Type 0803 Relatively small filament (0,7-0,8μm 50-150μm in length and diameter) motionless, straight or slightly curved, unbranched and is extended on the surface of the flake or free in solution. The cells are rectangular (0.8 x 1,5-2,0μm) and easy to see. It has no sheath growth of sessile bacteria or sulfur granules. The color is negative Gram and Neisser without intracellular granules. This is filamentous is associated with low F / M.

Type 0092

Type 0092 Relatively small filament (10-60μm in length and 0,8-1,0μm of diameter), motionless, straight or bent irregularly, which develops mainly within the flake and has no branches. The cells are rectangular (0.8 x 15μm) with little visible septum and no indentations. It does not present sheath, sulfur granules or growth of sessile bacteria. The color is Gram negative and positive Neisser. It may contain intracellular granules and trichome thickens after Neisser coloring. It causes Bulking problems due to the formation of coarse flakes. It is associated with facilities operating at low or very low F / M and long age sludge.

Type 0961

Relatively short filament (0,8-1,4μm 40-150μm in length and diameter) motionless, straight, unbranched, extending from the flake surface. The cells are rectangular and irregular (0.8-1.4 x 1,5-4μm) with a rigid trichome. The filament can sometimes be seen in bundles when found abundantly. The color is negative Gram and Neisser, no cell inclusions. It does not present sessile growth. Usually easy to identify because of its transparent appearance in some parts of the trichome, without any internal structures. It has no beads of sulfur or true sheath, but sometimes a viscous coating is observed which may be confused with one. It is associated with low values of F / M and wastewater containing more easily biodegradable compounds.

Microthrix parvicella

Narrow filament (diameter <1μm) but long (100-400μm) motionless without branches, irregular and in a convoluted way, developing inside the flake forming tangles or skeins and causing foaming and bulking problems. The cells are not visible, has no sheath, sulfur granules or sessile growth. May appear empty spaces inside the trichome, that may be mistaken with the existence of a sheath. The color is Gram positive and Neisser negative with Neisser positive beads. The granules of intracellular PHB may provide a frizzed effect to trichomes. The growth of this filamentous bacterium is favored by several factors that may appear isolated or combined: Low F / M, long sludge age, high content of oils and fats and low concentrations of dissolved oxygen. The overgrowth of this filamentous occurs predominantly in the spring and in installations with biological nutrient removal, accompanied by the appearance of nitrites. It is a common cause of foaming, which is characterized by being thick and brown.

Nocardia spp.

Irregular filament <200μm long and <1,0μm in diameter, motionless and endowed with true ramifications, developing inside the flake or free in solution. The cells are not observable at the optical microscope, however, are irregular and without indentation (1.0 x 1.0-2.0 one). They do not have sheath, sulfur granules or sessile growth. The color is Gram positive and Neisser negative with Neisser positive granules and PHB. It is the most common cause of foaming, being thick and brown staining. This filamentous is associated with effluents presenting a high content of oils and fats or surface-active substances and facilities with high sludge age, usually more than nine days, low F / M and poor oxygenation.

Nostocoida limicola I

Average Filament size (100m-200μm long and 0,6-0,8μm of diameter) motionless, inclined or convoluted, which may be inside the flake or in the solution. The cells are oval or disc-shaped (0,6-0,8μm x 0,6-0,8μm). They do not present sheath or sessile growth. Gram Coloring is positive and Neisser without the presence of sulfur granules. This filamentous is associated with effluents presenting a long age of sludge, low F / M, lack of nutrients and low concentrations of dissolved oxygen.

Nostocoida limicola II

Filament larger than N. limicola I, 100-200μm long and 1,2-1,4μm of diameter. Presents oval cells, discoidal or round with visible septa and indentações. It does not present sheath, sulfur granules or sessile growth. May present PHB granules, responses to Gram coloration and Neisser are variable and may have real ramifications. This filamentous is associated with effluents presenting a long age of sludge, low F / M, lack of nutrients and low concentration of dissolved oxygen.
 

Nostocoida limicola III

Large filament (200-300μm long and 1,6-2,0μm of diameter), motionless, with convoluted growth convoluted extending beyond flake surface. The cells are large and oval (1.6-2,0μm) with septum and clearly visible indentation. It has no sheath or sulfur granules, however, PHB granules may be observed. Coloration is generally positive Gram and Neisser. This is associated with long filamentous sludge age, low F / M, lack of nutrients and low concentrations of dissolved oxygen.

Haliscomenobacter hydrossis 

Small filament (20-100μm long and 0,5μm of diameter) motionless, straight or inclined without branching, which can be found lying outside the flake surface or in the solution. It presents sheath, but this is only visible when gaps appear along the trichomes and growth of sessile bacteria can be observed. It has no visible cells, cell septa, intracellular or sulfur granules. The coloration is Gram and Neisser negative.The growth of this filamentous is associated with facilities with insufficient oxygenation, low value of F / M, nutritional deficiency and / or high concentrations of rapidly biodegradable substances.

Type 0581

Medium-sized filament (100-200μm long and 0,5-0,8μm of diameter), motionless, slightly curled, unbranched, with rectangular cells. It is mainly found within the structure of the flakes, but may be present free in the solution. The color is Gram and Neisser negative. It does not present sessile growth, sulfur granules or sheath. This filament is usually found in environments where there is low F / M.

Type 1863

Small filament (20-50μm long and 0,8μm of diameter) motionless, without ramifications of irregular shape that develops inside the flake or solution. The cells are oval with indentations to the septum (0.8-1.2 x 1,5μm). It does not present sheath, sulfur granules or sessile growth. The color is Gram and Neisser negative, but there may be positive Neisser granules. This filament is occasionally observed as a cause of foam formation. Usually it does not cause bulking problems, however, it can cause foaming its tendency to grow in solution. It is associated with facilities with low dissolved oxygen concentration, high concentration of rapidly biodegradable substances, presence of oils and grease and high F / M.

Type 0411

Relatively small filament (50-150μm long and 0.8 of diameter), motionless, irregularly shaped and with no branching. The cells are round and look like lengthened rods (0.9 x 1,5μm). It has no sheath, attached growth or intracellular granules. It can be found extended from the structure of the flakes. Cell septa are clearly observed and the coloration is Gram and Neisser negative. This filamentous bacterium is associated to septic effluent, with organics or sulphides, which can also be associated with the generation of organic acids.