JPS5942096A - Biological treatment of waste water containing organic material - Google Patents

Abstract

PURPOSE:To clean up stably waste water having pollution of middle and high concn. without dilution, by treating part of the waste water in respective anaerobic tanks and aerobic tanks which treat org. polluting components of middle and low concn. and middle and high concn. respectively in separate activation tanks and returning the same into the respective tanks. CONSTITUTION:The waste water of middle and low concn. contg. org. polluting components such as waste water of fishery processing, waste water of night soil, etc. is fed successively from the 1st conditioning and anaerobic tank 1 to the 1st aerobic tank 2, whereafter the waste water is mixed with the polluted waste water of middle and high concn. having the same polluting components as the above-described polluting components passed through the 2nd conditioning and anaerobic tank 3. The mixed water is fed from a separator 4 through the 2nd aerobic tank 5 to a settling and separating tank 6. The aerobic sludge separated in said tank is returned to the tank 2 and the tank 5. Part of the waste water in the tanks 1, 3 and the tanks 2, 5 is returned to respectively separate activation tanks 9, 10, 13, 16, where the water is aerated and stirred. The aerated water is returned to the original tanks, whereby the polluted waste water of middle and high concn. is cleaned up without dilution.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a biological treatment method for wastewater containing organic substances, which can treat medium-high concentration wastewater without diluting it.

The inventors of this invention previously filed a patent application filed in 1986-115.
No. 716, a useful biological treatment method was proposed as an alternative to the conventional activated sludge method for biological treatment of wastewater containing organic substances. The features of this biological treatment method will be explained based on the flow sheets shown in Figures 1 and 2. First, as shown in Figure 1, medium-high concentration wastewater consisting of the same or similar pollutant components will be treated. and medium- and low-concentration wastewater,
The medium- and low-concentration wastewater is transported from the first adjustment anaerobic tank 1 to the first aerobic tank 2.
After water is sequentially sent to the water, it is mixed with the medium-high concentration wastewater that has passed through the second adjustment anaerobic tank 3, and sent from the separation device 4 to the sedimentation separation tank 6 via the second aerobic tank 5. The separated aerobic sludge is mixed with medium and low concentration wastewater discharged from the first adjustment anaerobic tank 1 and returned to the first aerobic tank, and the separation device 4
The wastewater treatment circulation system mixes the liquid with the liquid part from the wastewater and returns it to the second aerobic tank 5, and in the first adjustment anaerobic tank 1, anaerobic bacteria including facultative anaerobic bacteria have appeared While aeration and agitation suitable for generating anaerobic sludge is performed, aerobic bacteria including Zoogloea bacteria returned from the wastewater containing this anaerobic sludge and the sedimentation separation tank 6 become apparent, and the anaerobic bacteria By mixing latent aerobic sludge to produce sludge and aerating and stirring it in the first aerobic tank 2, aerobic sludge is created in which aerobic bacteria are exposed and anaerobic bacteria are latent, and this aerobic sludge is and wastewater containing anaerobic sludge in which anaerobic bacteria including facultative anaerobic bacteria produced by aeration and stirring in the second adjustment anaerobic tank 3 are mixed to generate new sludge. The new sludge is separated from the liquid part by the separator 4 and discharged to the outside of the wastewater treatment circulation system, and the liquid part is mixed with the aerobic sludge returned from the sedimentation separation tank 6 and sent to the second aerobic tank 5. After activating aerobic bacteria by aeration and stirring, the wastewater containing this aerobic sludge is sent to the sedimentation separation tank 6, and the supernatant liquid separated from the aerobic sludge is discharged as treated water to the outside of the wastewater treatment circulation system. As described above, the aerobic sludge is returned to the inlets of the first aerobic tank 2 and the second aerobic tank 5, and as shown in FIG. The separated aerobic sludge is returned to the first aerobic tank 2 and the second aerobic tank 5, and is also distributed and returned to the first adjusted anaerobic tank 1 and the second adjusted anaerobic tank 3.

Compared to the conventional activated sludge method, this biological treatment method is more effective than the conventional activated sludge method, in which aerobic bacteria contained in medium- and low-concentration wastewater treated under aerobic conditions become apparent and anaerobic bacteria become latent. The new sludge produced by mixing pneumatic sludge with anaerobic sludge in which anaerobic bacteria contained in medium-high concentration wastewater, which is composed of the same or similar pollutant components as the medium-low concentration wastewater, has become apparent, Since the pollutant components contained in the water are rapidly purified, there is no need to dilute it several tens of times when treating medium and high concentration wastewater as in the past.
This has the effect of reducing the size of each device and simplifying operation, and furthermore, the amount of aeration in each aerobic tank and each adjusted anaerobic tank is significantly smaller than in the conventional activated sludge method. Because the system can be operated easily, it has the advantage of reducing operating costs.

However, if there is a sudden change in the pollutant components or concentration of wastewater, changes in weather conditions, or other changes in physical and chemical conditions, the survival conditions for bacteria in the wastewater treatment circulation system may change due to these factors. This fluctuation makes it impossible to perform wastewater treatment smoothly, and as a result, there is a drawback that a great deal of effort is required to stabilize the wastewater treatment circulation system.

This invention was made in view of the above circumstances, and even when there is a sudden change in the pollutant components or concentration of wastewater, a change in weather conditions, or other physicochemical changes, the wastewater treatment cycle can be improved. The purpose is to stabilize the system and perform smooth wastewater treatment, and its features include the first adjustment anaerobic tank 1, the first aerobic tank 2, and the second
Part of the wastewater in the adjustment anaerobic tank 3 and the second aerobic tank 5 is taken out to separate activation tanks, where the C/N ratio is adjusted and inorganic substances are added, and in these activation tanks, the respective tanks 1, After performing aeration and agitation under the same conditions as in 2, 3, and 5, the wastewater in each activation tank was transferred to each tank 1.
, 2, 3, and 5.

The method of this invention will be explained in detail below with reference to FIG.

This method of the invention involves sequentially sending medium-low concentration wastewater from a first adjusted anaerobic tank 1 to a first aerobic tank 2, and then passing it through a second adjusted anaerobic tank 3 containing pollutant components that are the same as or similar to the medium-low concentration wastewater. The aerobic sludge separated in the sedimentation separation tank 6 is mixed with medium-high concentration wastewater and sent from the separation device 4 via the second aerobic tank 5 to the sedimentation separation tank 6. In the wastewater treatment circulation system, which mixes with the medium- and low-concentration wastewater coming out and returns it to the first aerobic tank 2, and also mixes it with the liquid part from the separation device 4 and returns it to the second aerobic tank 5, the first adjusted anaerobic It is designed to promote the activity of bacteria in the wastewater in the tank 1, the first aerobic tank 2, the second adjusted anaerobic tank 3, and the second aerobic tank 5.

In this invention, medium-high concentration wastewater and medium-low concentration wastewater consisting of the same or similar pollutant components include, for example, boiled broth, blood juice, etc. in the seafood processing process of mackerel and sardines, and medium-high concentration wastewater refers to general process wastewater. This is called low concentration wastewater. In addition, if raw human waste is considered medium-high concentration wastewater, general city sewage and diluted human waste fall under medium-low concentration wastewater. Furthermore, the medium-high concentration wastewater includes methane fermentation desorbed liquid in addition to the untreated raw liquid wastewater as described above.

Wastewater includes seafood processing wastewater, accumulated human waste wastewater, agricultural processing wastewater,
Any wastewater containing other organic substances can be treated by the method of the present invention, regardless of its type.

Among the bacteria that act in the wastewater treatment circulation system of this invention, aerobic bacteria include Zoogloea bacteria, other yeasts are also included, and anaerobic bacteria include facultative anaerobic bacteria that have some aerobic properties. sexual bacteria, such as lactic acid bacteria (L
actobacillus), Pediococcus (P
ediococcus), streptococcus (St
genus repto-coccus, Bacillus
Bacteria belonging to the genus S. lus) are essential, and other obligate anaerobic bacteria may also be included. When facultative anaerobic bacteria contain bacteria belonging to the genus Lactobacillus, specific effects described below are produced. These aerobic bacteria and anaerobic bacteria are previously introduced into the wastewater treatment circulation system before the system starts operating, and from then on, those that have grown naturally in the system are used.

The medium-low concentration wastewater is sent from the first adjustment anaerobic tank 1 to the first aerobic tank 2, the separation device 4, the second aerobic tank 5, and the sedimentation separation tank 6, and is contaminated with the same or similar pollution as the medium-low concentration wastewater. The medium-high concentration wastewater consisting of components is mixed with the wastewater exiting the first aerobic tank 2 from the second adjustment anaerobic tank 3 and sent to the separation device 4, the second aerobic tank 5, and the sedimentation separation tank 6.

The medium-low concentration wastewater is collected in the first adjustment anaerobic tank 1, where operations such as equalizing the liquid, adding nutrients, and adjusting the pH are performed as necessary. Aerated and stirred. This aeration agitation is performed in the wastewater in order to proliferate anaerobic bacteria including facultative anaerobic bacteria living in the first adjusted anaerobic tank 1 and to generate anaerobic sludge in which these anaerobic bacteria are exposed. Since it provides a small amount of dissolved oxygen evenly, it is empirically proven that the amount of aeration per unit pollutant should be weak, usually about one-tenth or less of the amount of aeration in the first aerobic tank 2. It has been experimentally proven. This is because if a larger amount of aeration is performed, although the wastewater is sufficiently agitated, facultative anaerobic bacteria become inactive and anaerobic sludge is not produced. In addition, in this first adjustment anaerobic tank 1, a part of the wastewater in the tank is once pumped to the pump 8.
After that, the mixture is guided to the activation tank 9, where the C/N ratio is adjusted and inorganic substances are added, and aeration and agitation under the same conditions are performed in the first adjustment anaerobic tank 1 for a predetermined period of time using air sent from the blower 7. , the wastewater in this activation tank 9 is returned to the first adjustment anaerobic tank 1. The capacity of this activation tank 9 may normally be about 1/100 to 1/1000 of the capacity of the first adjustment anaerobic tank. Further, the C/N ratio is appropriately selected and adjusted within the range of 10 to 25 depending on the pollutant components of the wastewater. This C/
Adjusting the N ratio activates anaerobic bacteria contained in wastewater,
This is done to speed up the proliferation rate, but the C/N
If the ratio is high, add nitrogen components such as urea to reduce the C
/N ratio is low, it is increased by adding carbon components such as waste molasses. Like the adjustment of the C/N ratio, the addition of inorganic substances is done to activate the anaerobic bacteria contained in the wastewater and increase their growth rate. A solution containing about 50% of other necessary salts is added to about 1/300 to 1/1000 of the volume of the activation tank 9. The time for which wastewater is retained in the activation tank 9 is 10 times the division time of facultative anaerobic bacteria present in the wastewater.
The standard is about twice as long, specifically about 2 hours and 30 minutes.
Extend or shorten residence time as necessary due to wastewater conditions or other reasons. The wastewater in the first adjustment anaerobic tank 1 is supplied to the activation tank 9 by supplying the above-mentioned predetermined amount all at once and performing the above-mentioned treatment, and then supplying the wastewater in the activation tank 9 all at once. A so-called batch process in which the wastewater is returned to the first adjusted anaerobic tank 1 is standard, but if the composition of the wastewater is not particularly suitable for the growth of anaerobic bacteria, a fixed amount may be continuously supplied. As mentioned above, the anaerobic bacteria contained in the wastewater treated in the activation tank 9 have been activated, and the wastewater is in the most suitable state for promoting microbial decomposition of organic matter. By returning the wastewater in the first regulating anaerobic tank 1 to the first regulating anaerobic tank 1, the wastewater is also transferred to this activation tank 9.
Similar to the wastewater returned from the wastewater, the state is suitable for promoting microbial decomposition of organic matter, that is, the anaerobic bacteria in the wastewater are activated. The batch treatment of the wastewater in the activation tank 9 may be performed continuously depending on the composition of the wastewater, but it is performed continuously only when there is a possibility that the treatment system cannot operate smoothly due to changes in the various conditions of the wastewater. You may also do this by doing this. The temperature of the waste water in the activation tank 9 is the first
The temperature of the wastewater in the anaerobic tank 1 is preferably within ±10°C, but is most preferably 30°C or more and 32°C or less.

The medium and high concentration wastewater is collected in the second adjustment anaerobic tank 3, where, like the medium and low concentration wastewater, the wastewater is adjusted as necessary and aerated and agitated to bring out facultative anaerobic bacteria and anaerobic bacteria. anaerobic sludge is produced. In addition, this second adjustment anaerobic tank 3 also has an activation tank 1 similar to the first adjustment anaerobic tank 1.
A part of the wastewater in the tank is once guided to the activation tank 10 by the pump 11, and the C/N ratio is adjusted and inorganic substances are added. After aeration and agitation under the same conditions as in the above are performed using air sent from the blower 7, the wastewater in the activation tank 10 is returned to the second adjustment anaerobic tank 3 again.

The wastewater containing anaerobic sludge in which anaerobic bacteria have become apparent and exits from the first adjustment anaerobic tank 1 is returned from the sedimentation separation tank 6 by the sludge pump 12. The new sludge generated by mixing with the sludge is charged into the first aerobic tank 2. The mixing ratio of the two is such that the solids concentration is equal or a little more aerobic sludge is mixed.

These two different types of sludge have contradictory physicochemical properties, and among these contradictory physicochemical properties, the relationship between aerobic sludge and anaerobic sludge due to Coulomb force and van der Waals force is Strong cohesive forces between the two sludges result from increased compatibility and additive effects such as the formation of certain polymeric bonding reactions between the two sludges and the adhesive force due to the mucous membranes formed by aerobic bacteria. It will be done. Due to this strong cohesive force and the effect of incorporating dissolved components as coagulation progresses, new sludge containing both aerobic and anaerobic bacteria is generated, and the purification effect of wastewater is promoted. . Incidentally, aerobic sludge and anaerobic sludge produced from wastewater containing the same or similar pollutant components have strong cohesion as described above, but on the other hand, aerobic sludge produced from different wastewater It has been experimentally found that almost no cohesive force occurs between sludge and anaerobic sludge. This indicates the existence of a type of polymer bonding reaction, rather than an aggregation reaction or simply a Coulomb force or van der Waals force.

Further, this first aerobic tank 2 is also provided with an activation tank 13 similar to the first anaerobic tank 1 and the second anaerobic tank 3, and once a part of the wastewater in the tank is activated by a pump 14, 13, the C/N ratio is adjusted and inorganic substances are added, and the same row crop is aerated and stirred in the first aerobic tank 2 for a predetermined period of time using air sent from the blower 7.
The waste water in the activation tank 13 is returned to the first aerobic tank 2 again.

The capacity of the activation tank 13 for the first aerobic tank 2, the preferred C/N ratio range, the method of adjusting the C/N ratio, the addition of inorganic substances, and the retention of activated wastewater in the tank 13 for aeration and agitation. The time, batch processing is standard, etc. The purpose of installation of the activation tanks 9 and 10 provided in the first adjustment anaerobic tank 1 and the second adjustment anaerobic tank 3 and the main activation tank 13 is to activate aerobic bacteria. They are the same, except that they are transformed into Regarding the temperature conditions in the activation tank 13, it is desirable that the temperature be within ±5°C of the temperature of the wastewater in the first aerobic tank 2, but the most desirable range is 25°C or more and 27°C or less. Here, although there is a difference in the temperature of the wastewater in the activation tanks 9 and 10 provided in the first adjusted anaerobic tank 1 and the second adjusted anaerobic tank 3, there is a difference in temperature between the target bacterial groups and the external temperature conditions. This is due to the different dynamics.

The newly generated sludge is transferred to the first aerobic tank 2.
By aerating and stirring in the activation tank 13 and further activating the aerobic bacteria, the aerobic sludge becomes an aerobic sludge in which the aerobic bacteria are exposed and the anaerobic bacteria are latent, and the sludge is discharged from the first aerobic tank 2 together with the wastewater. The sludge is mixed with wastewater containing anaerobic sludge discharged from the second regulating anaerobic tank 3, and is then input into the separation device 4 together with sludge produced for the same reason as described above. The mixing ratio of the two is such that the solids concentration is equal or a little more aerobic sludge is mixed. The generation of this new sludge promotes the purification effect of the wastewater containing anaerobic sludge discharged from the second regulating anaerobic tank 3. In addition to the above-mentioned microorganism aggregation operation, if the treatment efficiency is to be further improved, a necessary amount of an organic or inorganic flocculant may be added in the separation device 4. Furthermore, this new sludge is separated from the liquid part in the separator 4, and then separated into solid and liquid by the sludge dehydrator 15, and the solid part is discharged out of this wastewater treatment circulation system, and the liquid part is removed from the sedimentation separation tank 6 as sludge. The sludge is mixed with the aerobic sludge returned by the pump 12 and fed into the second aerobic tank 5.

The separation device 4 is not limited to the sedimentation tank type shown in the figure, but also includes devices using other physical or mechanical means.

Also, in this second aerobic tank 5, the first adjustment anaerobic tank 1, the second
Activation tank 16 similar to the adjustment anaerobic tank 3 and the first aerobic tank 2
A part of the wastewater in the tank is once guided to the activation tank 16 by the pump 17, and the C/N ratio is adjusted and inorganic substances are added. After performing aeration and agitation under the same conditions using air sent from the blower 7, the wastewater in the activation tank 16 is returned to the second aerobic tank 5. The conditions of this activation tank 16 are the same as those of the activation tank 13 provided in the first aerobic tank 2. Aeration stirring and activation tank 1 in this second aerobic tank 5
Due to the activation of aerobic bacteria in step 3, aerobic bacteria become apparent in the second aerobic tank 5, and aerobic sludge with latent anaerobic bacteria becomes activated and is then sent to the sedimentation separation tank 6. Separated into supernatant liquid and aerobic sludge. This supernatant liquid is discharged as treated water to the outside of this wastewater treatment circulation system, and the aerobic sludge is returned to the first aerobic tank 2 and the second aerobic tank 5 by the sludge pump 12 as described above.

In addition, in the aerobic sludge in the above explanation, aerobic bacteria including Zooglea bacteria that were introduced into the wastewater treatment circulation system before its operation started or that naturally proliferated afterward have become apparent. Anaerobic bacteria, including facultative anaerobic bacteria, are latent. In addition, similar to the first adjusted anaerobic tank 1, aeration and agitation in the first aerobic tank 2, second aerobic tank 5, second adjusted anaerobic tank 3, and each activation tank 9, 10, 13, and 16 are also performed using a blower. The aeration is carried out using air sent in from 7, but it goes without saying that other means of aeration and agitation may be used instead.

Furthermore, in the first adjusted anaerobic tank 1 and the second adjusted anaerobic tank 3, anaerobic bacteria including facultative anaerobic bacteria, which were introduced before the start of operation, proliferate despite the inflow and outflow of wastewater due to aeration and agitation. Anaerobic sludge is continuously generated, but if the pollution concentration of wastewater decreases for various reasons, it may become impossible for the anaerobic bacteria to grow.
As shown in the figure, a wastewater treatment circulation system can be provided in which the aerobic sludge separated in the sedimentation separation tank 6 is also returned to the first adjustment anaerobic tank 1 and the second adjustment anaerobic tank 3. In the case of this system, the anaerobic bacteria latent in the aerobic sludge can be brought to the surface and multiplied by the aeration and agitation described above in the first adjusted anaerobic tank 1 and the second adjusted anaerobic tank 3. . Therefore, in this system, the wastewater that has exited the first adjusted anaerobic tank 1 and the second adjusted anaerobic tank 3 is an anaerobic sludge in which anaerobic bacteria inhabit, where anaerobic bacteria have become apparent and aerobic bacteria have become latent. However, the wastewater containing this anaerobic sludge is mixed with the aerobic sludge returned from the sedimentation separation tank 6, where aerobic bacteria are exposed and anaerobic bacteria are latent, to generate new sludge. is the same as the above system. Also in this system, the wastewater in the first adjusted anaerobic tank 1, the first aerobic tank 2, the second adjusted anaerobic tank 3, and the second aerobic tank 5 is activated by the activation tanks 9, 10,
13 and 16 to activate bacteria in the wastewater is also the same as in the above system.

In the above two wastewater treatment circulation systems, when Lactobacillus bacteria are included as facultative anaerobic bacteria, the action of the Lactobacillus bacteria further increases the strong sludge flocculation effect and at the same time produces anaerobic sludge. is promoted, the progress of the putrid state accompanying the growth of putrefactive bacteria under anaerobic conditions in the first adjusted anaerobic tank 1 and the second adjusted anaerobic tank 3 is delayed, and therefore, the generation of putrid odor is also prevented. be.

As is clear from the above explanation, in the method of the present invention, of medium-high concentration wastewater and medium-low concentration wastewater consisting of the same or similar pollutant components, the medium-low concentration wastewater is transferred from the first adjustment anaerobic tank 1 to the first preferred anaerobic tank 1. After the water is sequentially sent to the air tank 2, it is mixed with the medium-high concentration wastewater that has passed through the second adjustment anaerobic tank 3, and sent from the separation device 4 to the sedimentation separation tank 6 via the second aerobic tank 5, where it is separated by sedimentation. The aerobic sludge separated in the tank 6 is mixed with medium and low concentration wastewater discharged from the first adjustment anaerobic tank 1 and returned to the first aerobic tank 2, and mixed with the liquid portion from the separation device 4 to be mixed with the second adjustment anaerobic tank. Air tank 5
or the aerobic sludge separated in the sedimentation separation tank 6 in the system is mixed with the medium-low concentration wastewater discharged from the first adjustment anaerobic tank 1 and returned to the first aerobic tank 2. At the same time, the first adjusted anaerobic water is mixed with the liquid part from the separation device 4 and returned to the second aerobic tank 5, and further returned to the first adjusted anaerobic tank 1 and the second adjusted anaerobic tank 3. Tank 1, first aerobic tank 2, second adjusted anaerobic tank 3 and second
Activation tanks 9, 10, 13, 16 are provided in the aerobic tank 5, and part of the wastewater in each tank 1, 2, 3, 5 is guided to these activation tanks 9, 10, 13, 16, After activating the anaerobic bacteria or aerobic bacteria, they are returned to the original tanks 1, 2, 3, and 5.
The bacteria in each tank 1, 2, 3, and 5 are also activated, and the microorganisms contained in the wastewater are activated, that is,
Since the state is adjusted to be suitable for decomposing organic matter in wastewater, the wastewater treatment system can be stabilized.

Therefore, when there is a sudden change in the pollutant components or concentration of wastewater, changes in weather conditions or other physicochemical changes can be adequately coped with, and smooth and efficient wastewater treatment can be performed.

[Brief explanation of the drawing]

1 and 2 each show a flow sheet of a wastewater treatment circulation system without an activation tank, and FIGS. 3 and 4 each show an example of a flow sheet of the present invention. 1... First adjustment anaerobic tank, 2... First aerobic tank, 3...
・Second adjustment anaerobic tank, 4... Separation device, 5... Second aerobic tank, 6... Sedimentation separation tank, 9, 10, 13, 16...
・Activation tank.

Claims (1)

[Scope of Claims] 1. Among medium-high concentration wastewater and medium-low concentration wastewater consisting of the same or similar pollutant components, the medium-low concentration wastewater is sequentially sent from the first adjustment anaerobic tank to the first aerobic tank, and then The mixture is mixed with the medium and high concentration wastewater that has passed through the second adjustment anaerobic tank, and then sent to the second anaerobic tank.
The aerobic sludge is sent to the sedimentation separation tank via the aerobic tank, and the aerobic sludge separated in the sedimentation separation tank is mixed with the medium and low concentration wastewater discharged from the first adjustment anaerobic tank and returned to the first aerobic tank and separated. A wastewater treatment circulation system that mixes with the liquid part from the device and also returns it to the second aerobic tank, in the first regulating anaerobic tank,
Aeration and agitation suitable for producing anaerobic sludge in which anaerobic bacteria including facultative anaerobic bacteria are exposed is carried out, and wastewater containing this anaerobic sludge and Zooglaia (Zoo-glare) returned from the sedimentation separation tank are Aerobic sludge, in which aerobic bacteria including bacteria of the genus gloea) have become apparent and anaerobic bacteria have become latent, is mixed to produce sludge, which is then aerated and stirred in the first aerobic tank, whereby aerobic bacteria become apparent and anaerobic sludge is produced. This includes aerobic sludge in which bacteria have become latent, and anaerobic sludge in which anaerobic bacteria including facultative anaerobic bacteria have become apparent, which is generated by aerating and agitating wastewater containing this aerobic sludge in a second adjustment anaerobic tank. The wastewater is mixed to produce new sludge, which is separated from the liquid part by a separator. This new sludge is discharged outside the wastewater treatment circulation system, and the liquid part is returned to the aerobic sludge from the sedimentation separation tank. After activating aerobic bacteria by aerating and stirring in the second aerobic tank, the wastewater containing this aerobic sludge is sent to a sedimentation separation layer, and the supernatant liquid separated from the aerobic sludge is used as treated water. The aerobic sludge is discharged to the outside of the wastewater treatment circulation system as described above, and the aerobic sludge is returned to the inlets of the first and second aerobic tanks as described above.
Part of the wastewater in the first adjusted anaerobic tank, second adjusted anaerobic tank, first aerobic tank, and second aerobic tank is taken out to separate activation tanks to adjust the C/N ratio and add inorganic substances. and after performing aeration and agitation in these activation tanks under the same conditions as in each of the above-mentioned tanks, the wastewater in each activation tank is returned to the original each of the above-mentioned tanks. Biological treatment methods for wastewater. 2. The method for biological treatment of wastewater containing organic substances according to claim 1, wherein the facultative anaerobic bacteria are facultative anaerobic bacteria including bacteria of the genus Lactobacillus. 3. Among medium-high concentration wastewater and medium-low concentration wastewater consisting of the same or similar pollutant components, the medium-low concentration wastewater is sent from the first adjustment anaerobic tank to the first aerobic tank in order, and then to the second adjustment anaerobic tank. It is mixed with the medium-high concentration wastewater that has passed through the separation device and then sent to the second
The sludge is sent to a sedimentation separation tank via an aerobic tank, and the aerobic sludge separated in the sedimentation separation tank is mixed with medium and low concentration wastewater discharged from the first adjustment anaerobic tank and sent to the first aerobic tank. It is mixed with the liquid part from the separator and returned to the second aerobic tank, and then the first
A wastewater treatment circulation system that also returns the wastewater to a regulated anaerobic tank and a second regulated anaerobic tank, wherein in the first regulated anaerobic tank, anaerobic sludge in which anaerobic bacteria including facultative anaerobic bacteria are manifested is generated. At the same time, aerobic bacteria including Zoogloea bacteria, which is returned from the wastewater containing this anaerobic sludge and the sedimentation separation tank, become apparent and the anaerobic bacteria become latent. Aerobic sludge is mixed with aerobic sludge to produce sludge, which is then aerated and stirred in a first aerobic tank to produce aerobic sludge in which aerobic bacteria are exposed and anaerobic bacteria are latent, and wastewater containing this aerobic sludge and a second New sludge is generated by mixing wastewater containing anaerobic sludge in which anaerobic bacteria, including facultative anaerobic bacteria, generated by aeration and agitation in a controlled anaerobic tank are produced and separated from the liquid part in a separation device. This new sludge is then discharged outside the wastewater treatment circulation system, and the liquid portion is mixed with the aerobic sludge returned from the sedimentation separation tank and aerated and stirred in the second aerobic tank to activate aerobic bacteria. After this, the wastewater containing this aerobic sludge is sent to a sedimentation separation tank, and the supernatant liquid separated from the aerobic sludge is discharged as treated water to the outside of the wastewater treatment circulation system. While returning to the aerobic tank and the second aerobic tank, it is also distributed and returned to the first adjusted anaerobic tank and the second adjusted anaerobic tank, and further, the first adjusted anaerobic tank, the second adjusted anaerobic tank, and the first aerobic tank A portion of the wastewater in the second aerobic tank is taken out to separate activation tanks, the C/N ratio is adjusted and inorganic substances are added, and aeration is carried out in these activation tanks under the same conditions as in each tank. A biological treatment method for wastewater containing organic substances, characterized in that after stirring, the wastewater in each activation tank is returned to the original respective tanks. 4. The method for biological treatment of wastewater containing organic substances according to claim 3, wherein the facultative anaerobic bacteria are facultative anaerobic bacteria including bacteria of the genus Lactobacillus.