What is the role of filamentous bacteria in water supply and drainage engineering? What characterist

There are three main types of filamentous bacteria: iron bacteria, sulfur bacteria, and jersey bacteria.

Iron bacteria are generally autotrophic filamentous bacteria that live in water that contains less oxygen but has more iron and carbon dioxide. They can oxidize the ferrous iron absorbed in their cells to high iron, which gives them energy. In order to meet the energy requirements, large quantities of ferrous iron must be oxidized to produce iron hydroxide.

This insoluble iron compound precipitates after being expelled from the cell. When there is a large amount of iron hydroxide precipitation in the water pipe, the water pipe's ability to carry water is reduced. In addition, the absorption of ferrous salts in the water by iron bacteria causes more of the iron that makes up the water pipes to dissolve into the water, accelerating the corrosion of steel pipes and cast iron pipes.

Sulfur bacteria are also generally autotrophic filamentous bacteria. They can oxidize hydrogen sulfide, sulfur, and other sulfides to sulfuric acid, thus obtaining energy. When sulfur bacteria multiply in water pipes, they are corrosive to pipes due to the production of strong acids.

Jersey bacteria are aerobic bacteria. It has high requirements for carbon in terms of nutrition and is very responsive, so a large amount of carbohydrates can accelerate the reproduction of jersey bacteria. In addition, jersey bacteria are not as resistant to certain pesticides as liquid chlorine, bleaching powder, etc.

Jersey bacteria have a strong ability to break down organic matter. There is a certain amount of jersey bacteria in the normal operation of the sewage treatment plant, which is beneficial for the removal of organic matter.

Filobacterium is not good for sewage treatment, which can make the sedimented sludge swell and affect the effluent quality.

The environment in which the activated sludge is exposed to adverse changes, and the overgrowth of filamentous bacteria is the cause of sludge expansion. Normal activated sludge contains certain filamentous bacteria, which is the skeleton material for the formation of activated sludge flocs. If the number of filamentous bacteria in the activated sludge is too small or absent, it cannot form large flocs, and the sedimentation performance is not good; The overgrowth of filamentous bacteria forms filamentous sludge expansion.

Under normal circumstances, the growth rate of mycelium is greater than that of filamentous bacteria, and there will be no overproduction of filamentous bacteria. However, in the harsh environment, due to its large surface area, filamentous bacteria have a stronger ability to resist the harsh environment than mycelium bacteria, and their number will exceed that of mycelium bacteria, resulting in excessive multiplication and expansion of filamentous sludge. Poor environment refers to high or low indicators of water quality, environmental factors and operating conditions. Another reason is that the physiological activity of the colloidal group is abnormal, which leads to the deterioration of the sedimentation performance of the activated sludge is that the inlet water contains a large amount of dissolved organic matter, so that the sludge load is too high, the lack of N, P or DO is insufficient, and the bacteria will secrete excessive polysaccharides into the body, which contain a lot of hydroxide groups and have hydrophilicity, so that the mud-water binding rate is as high as 400, and it is a viscous gel, so that the activated sludge can not effectively carry out sludge and water separation in the sedimentation stage.

Filamentous bacteria are divided into iron bacteria, sulfur bacteria, and jersey bacteria. Its main characteristic in metabolic processes is unbranched or pseudo-branching:

Iron bacteria: 1) Characteristics: filaments live unbranched in water with less oxygen and more iron and carbon dioxide, oxidizing ferrous iron to high iron.

2) Function: Cause corrosion and blockage of iron water pipes. Makes the water appear color, which affects the quality of the water.

Sulfur bacteria: 1) Characteristics: non-branching. Bézhattosa floats on ponds or marshes and is not fixed. Sulfur-emitting bacteria are fixed on substances such as micelles. Oxidation of hydrogen sulfide, sulfur, etc.

2) Function: Treatment of sulfur-containing wastewater; Bézhatosa can cause sludge swelling of activated sludge.

Jersey bacteria: 1) Characteristics: pseudo-branched; It can grow in a micro-oxygen environment with less dissolved oxygen; Strong ability to decompose organic matter. 2) Function: An important strain that constitutes a biofilm, is conducive to the removal of organic matter, and is easy to cause "sludge swelling".

In the normal operation of the wastewater biological treatment system, filamentous bacteria are the skeleton of biological flocs or biofilms, on which the mycelium is attached, and the filamentous bacteria form a reciprocal relationship with the mycelium, which can maintain the stability of the wastewater treatment system and improve the ability to resist shock loads, but excessive propagation will cause sludge expansion.

Filomycetes are parasitic fungi, and filamentous fungi are not a type of fungus, but a general term for a class of fungi. Their common feature is filamentous bodies.

Fungi have the function of decomposing carbohydrates, fats, proteins and other nitrogen-containing compounds, and this function is reflected in the degradation of COD, BOD and TN in water supply and drainage.

Its metabolic characteristics are similar to those of mammals, and they are heterotrophs, and as a class of organisms, fungi have obvious ability to use almost any carbon source as food, and water supply and drainage engineering uses this ability of fungi to degrade various organic carbon sources.

However, the malignant reproduction of filamentous bacteria can easily cause sludge expansion, resulting in sludge that is not easy to precipitate and the SVI value increases. In operation management, it is necessary to prevent sludge expansion by controlling a series of values, which is basically mentioned in this part of the textbook, and you need me to elaborate on it.

This is the role of filamentous bacteria in sewage treatment, that is, in activated sludge.

Filiform microorganisms are a general term for a large group of microorganisms that are connected to form filaments, including filamentous bacteria, filamentous fungi, filamentous algae, etc.

The function of filamentous microorganisms is closely related to the structure and morphology, and the filamentous morphology is conducive to its attachment and growth on the solid phase, maintaining a certain cell density, and preventing it from being swallowed by microanimals in a single cell state. The filamentous morphology has a large specific surface area, which facilitates the uptake of low-concentration substrates. Many filamentous microorganisms have a gelatinous sheath on the surface that secretes mucus, and the mucus layer ensures a certain concentration of extracellular enzymes and reduces the flushing of cells by the water flow, which also contains specific antibodies to prevent other organisms from attaching.

According to the role of filamentous bacteria in the formation of sludge flocs, filamentous fungi can be divided into structural filamentous bacteria and unstructured filamentous hyphae. Under normal operating conditions, flocs with structural filamentous bacteria predominated, and the number of non-structural filamentous bacteria was small. There is an interdependent relationship between colloidal bacteria and structural filamentous bacteria, and filamentous microorganisms form a floc skeleton, which provides the necessary conditions for flocs to form larger particles while maintaining a certain degree of looseness.

The attachment of colloidal bacteria makes the floc have a certain sedimentation property and is not easy to be carried away by the effluent, and due to the attachment of colloidal bacteria, the structural filamentous bacteria obtain more stable and good ecological conditions, so these two types of microorganisms form a special symbiont in the activated sludge. Structural filamentous bacteria play a great role in ensuring the strength of sludge flocs. If there is no sufficient amount of filamentous bacteria, the strength of the sludge floc will be reduced, and the shear resistance will also be reduced, making the treated effluent turbid and the effluent quality worse.

However, in the case of overgrowth of filamentous bacteria, the number of filamentous bacteria may exceed that of colloidal bacteria, which makes the sludge loose structure, lighter in mass, less sedimentation, worse in sedimentation and compression, and produces sludge swelling, resulting in a decrease in the quality of sludge effluent.