Microorganisms in the sewage treatment plant biochemical system debugging, later stable operation and process adjustment process, plays a very important role in the indication, through the microscopic detection of the microbial status in the activated sludge, you can obtain the activated sludge correlation information, the production plays a certain role in guiding.
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In this paper, the relationship between microorganisms and sewage treatment is elaborated from five aspects, such as the collection of activated sludge samples, trait analysis, microbial indication, microbial atlas and case analysis; from the perspective of microscopy and professional considerations, the bacterial gel group is analyzed as a separate object, which has a certain pertinence.
1 Activated sludge microscopic sample collection
The impact of sample collection on the microscopic results is more obvious, the sampling is improper, and the microscopic results obtained will mislead us into regulating the parameters of the activated sludge. In order to avoid such situations, it is more important to follow the standard sampling method and clarify the sampling points.
01 Sample collection location
The location of the activated sludge samples collected and the monitoring of the sedimentation ratio of the activated sludge are the same as the mixture from the end of the aeration tank, and the activated sludge mixture at this location is optimal in terms of stability, flocculation, population number or protozoa representation.
(1) Stability
At the end of the aeration, the activated sludge is in a deceleration growth period, the activated sludge activity is reduced, and the stability becomes more reliable.
(2) Flocculation aspect
Because the activated sludge is in a deceleration growth period, the sedimentation of the activated sludge is more obvious, and the natural flocculation is better.
(3) Microbial population
This refers to the original vivid species population, and the main bacterial population of microorganisms is not discussed.
The vivid species group after the central plains of the activated sludge is dominated by non-activated sludge protozoa at the front end of the aeration tank, and the intermediate activated sludge protozoa dominates in the middle of the aeration tank, while the dominant protozoa species at the end of the aeration tank determine the functional traits of the activated sludge biological phase. The activated sludge mixture collected at this location was observed by biophase microscopy, and the results were more representative.
02 Method of detection solution collection
When we collect the mixture to be measured at the end of the aeration tank, we need to select a drop onto the slide for testing. The following points need to be noted for this process:
(1) Before the test, the activated sludge mixture should be continuously and slowly shaken to avoid flocculation precipitation. After the activated sludge is flocculated and precipitated, if it is stirred again, the flocculation effect that occurs subsequently will be slightly weakened, and the fine floc suspension of the supernatant will increase, which will cause certain misleading observation (such as the observed structure of the activated sludge is loose, small, not dense, light in color, etc.).
(2) Usually the tool used to collect activated sludge samples onto the slide is the rubber head dropper. The glue head dropper needs to be fully stirred before reaching into the collected activated sludge mixture, so that the activated sludge is suspended in the mixture, and the depth of the rubber head dropper into the mixture should also be controlled, generally to the middle of the mixture. After collection, the activated sludge mixture is moved to the slide, and a few drops of the mixture in the rubber head dropper can be squeezed out, and then a drop of activated sludge mixture is placed on the slide.
A drop of mixture taken on the slide, in the actual use of the process is excessive, in the cover of the coverslip will be partially overflowed and need to be wiped off, otherwise, the coverslip is easy to move on the slide, while the collected drop of the function of the sludge mixture will also be under the action of height difference, temperature and so on will also flow or move internally. For this purpose, it is necessary to wipe off this excess part of the activated sludge mixture, we can determine the droplet of activated sludge mixture that is wiped off according to the proportion of 1/4 of the activated sludge mixture, that is to say, in the sample to be tested after being wiped off, the actual sampling amount is 3/4 drops of activated sludge mixture.
2 Problems that need to be paid attention to for activated sludge microscopy
01 Avoid high temperature microscopy
Because the number of water samples on the downloaded slides is small in high temperature conditions, the sample water body will expand, and the rich fine bubbles will precipitate out to affect the observation effect.
02 Avoid direct sunlight
This can effectively prevent the occurrence of bubble precipitation and expansion in the sample to be examined, and avoid the existence of bubbles due to direct sunlight reflective, refractive and other phenomena and affect the observation effect. It also prevents eye damage.
03 Avoid vibration
To ensure the stability of observations and the safety of the microscope itself, the place where the microscope is placed needs to be safe.
04 Avoid low light
In the case that the microscope does not have its own supplementary light source, if the ambient illumination is less than 300Lx, the microscope is relatively dark when observing, so it is necessary to have a supplementary light source with the microscope to meet the needs of the observational illuminance.
05 Avoid light abnormalities
If the surrounding light is colored, then the color of the field of view observed in the microscope is usually also colored, which has a disturbing effect on observing the activated sludge traits.
3 Analysis of activated sludge traits
The capsular material of many bacteria fuses into clumps, containing many bacteria, called bacterial gelatinous clumps. Hygroplast is the main form of bacteria in sewage treatment, and in some sludge that is not suitable for protozoa growth, the treatment effect is judged by looking at the size and quantity of the hysteroid. Bacteria gel mass is of great significance in wastewater treatment:
(1) It can prevent bacteria from being swallowed by animals;
(2) It can enhance the resistance of bacteria to adverse environments, such as drought;
(3) The fungal glue group has an indicative role: the newborn bacteria glue group has good wastewater treatment performance, which is mainly manifested in its tight structure, strong ability to adsorb and decompose organic matter, and good sedimentation.
Aging bacteria glue mass, loose structure, poor ability to adsorb and decompose organic matter, poor sedimentation. In terms of color, the new fungal mice are light in color, or even colorless and transparent, and the aging bacteria are darker in color.
Through microscopic observation, we can judge the characteristics of the bacterial gel group according to the following factors:
(1) The number of bacteria and micelles
Counting in the existing situation, depending on the density of the bacterial gel mass in a certain volume, affected by sampling, sludge concentration, etc., it is generally difficult to analyze correctly, and it is generally not described when it is normal, and it is only recorded when a large change occurs.
(2) The shape of the fungal gel mass
According to the shape of the fungal gel mass, it is described as four forms: spherical, irregular, open, closed. True spherical flocs are not present in activated sludge, and nearly spherical clumps of fungal gel are often referred to as "spherical". If the shape is very different from the spherical shape, it is called "irregular shape", at which time there is a large protrusion on the side of the fungal gel mass. In a closed hysteroidal mass there is almost no open space, whereas in an open hysteroid, part of the hysteroid is clearly separated from another through one space.
(3) The tightness of the fungal gel group
Tightness is expressed in terms of weak and strong. In a weakly compact microcosmic mass, the binding of bacterial cells is very low and lacks a tight center, and the sides of this microcollectophore are easily destroyed by light pressure on the coverslip. There is no clear boundary between the hysteroid and the liquid, as there are many cells at its edges that are both in the liquid and in the microflora. Usually obviously there are many dispersed substances.
In the tightness of the microcells, the binding of bacterial cells is strong, there is a clear boundary between the bacterial gel group and the liquid, and the tightness of the bacterial micelles sometimes forms larger, strong granular flocs, which are observed under the microscope due to the large particle size and low light transmittance of the sludge, so the dark images are mostly presented.
(4) The size of the fungal gel group
According to the diameter size, it is divided into three cases: large (d>500μm), medium (150μm<d<500μm), small (d<150 μm), and the diameter is generally based on the farthest edge of the bacteriocoagin group.
(5) Composition of the fungal gel group
The composition of the fungal glue mass mainly refers to: how much aging sludge, the shape and size distribution of the bacteria glue mass, whether there are inorganic particles and abiotic organic particles, color, etc.
The degree of sludge aging refers to the proportion of bacterial cells that die in the activated sludge. The new bacteria mice are light in color, colorless and transparent, tight in structure, vigorous in vitality, and have strong adsorption and oxidation capacity; the aging bacteria mice are dark in color, loose in structure, not active, and have poor adsorption and oxidation capacity. According to the observed degree of sludge aging, the residual sludge discharge is adjusted so that the bacterial gel group is in the best active state.
The shape and size of the hysteroid are different, which also reflects the rich bacterial species of the hysteroid to a certain extent, and the rich bacterial mass has a higher impact resistance when the water quality changes.
The color of the fungal gel group is black, which may be insufficient dissolved oxygen in the aeration tank; the color of the bacteria mass turns pale and white, it may be that the dissolved oxygen of the aeration tank is too high or the inlet water concentration is too low, and the microorganisms in the sludge are oxidizing themselves due to lack of nutrients.
4 Activated sludge microscopic examination drawings
Under the normal operation of the sewage treatment plant, the activated sludge has large floccules, clean edges, tight structure, closed state, and good adsorption and settlement properties. Floccules take the fungal gel group bacteria as the skeleton, interspersed with the growth of some filamentous bacteria, but the number of filamentous bacteria is far less than that of the fungal gas group bacteria, micro-animals are mainly fixed ciliates, such as bell worms, cap ciliosis, tired branches, etc., you can also see the lintel fiber worm crawling on the flocculents, and occasionally you can see a small number of swimming ciliates, etc., rotifers grow actively.
When the operation of the sewage treatment plant is abnormal, the sludge appears with a loose floc structure and smaller floc particles, and a large number of swimming ciliates (beanoids, kidneyworms, grasshoppers, potozoans, trichomoniasis, etc.) organisms, carnioppods (amoeba spp., simple insects, etc.) are observed, and when this biological phase occurs, the sedimentation of the sludge is poor, affecting the separation of sludge and water.
To understand the changes in the sewage treatment process or the quality of the treated water, it is best to directly study and analyze the growth of bacteria. However, the time for the observation and classification of bacteria is very long, and it cannot play a role in guiding production instructions and forecasts in time. There is an interdependent functional relationship between microorganisms and bacteria; microbes are large and easy to observe; they are more sensitive to environmental changes than bacteria, and they are more likely to reflect environmental changes earlier and more easily. Directly observing the composition, quantity, growth and change of microorganisms can also reflect the growth and change of bacteria, that is, indirectly evaluate the quality of the sewage treatment process and treatment effect, and play a role in guiding production.
5 Microbial indicators of an overview
01 Activated sludge composition
(1) populations of active microorganisms with metabolic functions;
(2) Residues of endogenous microbial respiration of their own oxidation;
(3) Refractory organic matter adsorbed by sludge flocs;
(4) Inorganic substances adsorbed by sludge flocs.
Active microbial populations with metabolic functions include bacteria, fungi, protozoa, protozoa, etc., among which bacteria assume the main role of degrading pollutants.
The bacteria in the activated sludge are mainly heterotrophic prokaryotic bacteria, and the number of bacteria in the normal mature activated sludge is about 107 to 109 per milliliter of activated sludge. Bacteria are single-celled microorganisms that feed on lysate substances. The bacteria that form an advantage in activated sludge are related to the nature of contaminants in sewage and the operating conditions of the activated sludge method. Common dominant seedlings in activated sludge are: Bacillus alkali-producing spp., Bacillus bacillus, Bacillus flaviflus, Actinomycetes spp., Pseudomonas spp., C. clumps, Escherichia coli and so on. Some bacteria in the activated sludge, such as Mycelium mycobacterium, Bacillus bacillus, Bacillus flax, Nocaia reticulata, Pseudomonas and other bacteria have the ability to secrete adhesion substances, which provide conditions for bacteria to bond to each other and form bacterial gellocs. The fungal gel group has a certain adsorption and bonding effect on the tiny particles and soluble organic matter in the sewage, and promotes the formation of activated sludge flocs.
Fungi are multicellular heterotrophic microorganisms that belong to obligate aerobic microorganisms that survive by dividing, spranging and forming spores. Fungi require only half as much nitrogen as bacteria. Common fungi in the activated sludge method are tiny saprophytic or parasitic filamentous bacteria that break down carbohydrates, fats, proteins and other nitrogen-containing compounds. If a large number of sludge appears, the sludge expansion phenomenon will occur, which will seriously affect the normal operation of the activated sludge system. The presence of fungi in activated sludge methods is often related to water quality.
Carnithopods, flagellars, and cilia are three common types of protozoa in activated sludge. Protozoa are single-celled organisms that reproduce by dichotomy, mostly oxidizing heterotrophic bacteria, and their main food objects are bacteria. Therefore, changes in the water quality of treated water and bacteria in activated sludge directly affect the changes in the type and number of protozoa. In the early stage of the operation of the activated sludge method, mainly carnipods, flagellars, and then free-swimming ciliates, when the activated sludge matures and the treatment effect is good, creeping or attached ciliates dominate. Individual protozoa are large, can be observed by microscopy, can be used as indicator organisms, in the application of activated sludge method, often by observing the type and number of protozoa, indirectly judge the effect of sewage treatment. Therefore, the observation of the biological phase of the protozoa of activated sludge is one of the important means for the quality evaluation of activated sludge. In addition, the role of protozoa in preying on bacteria also ensures that the effluent quality of the activated sludge system is further improved, and it is the second largest sewage purification function bearer after bacteria.
The offsites that often appear in activated sludge are rotifers, nematodes and oligochaetes, which usually feed on bacteria, protozoa and fragments of activated sludge. Rotifers usually appear in systems with low organic content and good water quality, such as delayed aeration activated sludge systems, so the appropriate amount of rotifers is a sign of good and stable effluent quality.
02 Microbial indication effect
Microorganisms in the debugging process, post-stable operation and process adjustment, plays a very important role in the indication, through the microscopic examination according to the microbial situation in the activated sludge can be found in the various conditions of the activated sludge, its indication role is:
(1) When there are many hairy orders such as small-mouth bell worms, eight-bell worms, ditch bell worms, folded bell worms, bottle tired branches, micro-disc cap worms, and monocotylar worms), the treatment effect is good, and the effluent BOD5 and turbidity are low. (These species of the order Flange are fixed to flocs and flipped accordingly, and if they are also mixed with reptile microorganisms such as parabene, paranormal worms, pinnacles, and tracheal leafworms, etc., they can be called high-quality and mature activated sludge.)
(2) Small-mouth bellworm is often the dominant strain in the entire microbial system when the domestic sewage and industrial wastewater treatment effect is very good.
(3) If a large number of flagella appears, and there are very few hairs, it indicates that the purification ability is poor.
(4) When a large number of freely active ciliates appear, it indicates that the purification ability of the system is not strong, and the turbidity of the effluent may rise.
(5) If there are stalked ciliates, such as bell worms, twig worms, cover worms, rotifers, oligochaete microorganisms, it indicates that the biological system is in good condition, the effluent is clear, and the phenol removal rate is more than 90%.
(6) The large number of rootpods is often a manifestation of sludge poisoning.
(7) If a large number of twig insects appear in domestic sewage treatment, it is likely to be a sign of sludge expansion and flocculation.
(8) In the treatment of printing and dyeing wastewater, the tired branches are used as indicator organisms for the normal or improved state of the sludge.
(9) The appearance of bell worms in petroleum wastewater treatment indicates that the treatment effect is ideal.
(10) The appearance of excessive rotifers is a harbinger of the imminent expansion of the sludge.
Transferred from: Sewage Treatment Studio Source: Easy to build water supply and drainage, rural sewage, water environment and water ecology