JPS5952586A - Biological treatment of waste water containing organic substance - Google Patents

Abstract

PURPOSE:To enable to perform smooth efficient waste water disposal, even when various conditions such as contaminating components in waste water may change, by withdrawing a part of waste water in an anaerobic tank to an activation tank, activating anaerobes in it, and then returning it to the original anaerobic tank again. CONSTITUTION:In the circulating system for waste water disposal in which waste water (a) containing organic substance is sequentially sent from a conditioning tank 1 through an anaerobic tank 2, an intensive aeration tank 3 and a separation means 4, while sludge separated by the means 4 is returned to the tank 3, treatments in the tanks 2-4 are performed in the same way as those in conventional manner. In addition, a part of waste water in the tank 2 is withdrawn out to an activation tank 6 and aerobically agitated in the tank 6 under the same condition as that in the tank 2 while conditioning a C/N ratio and adding inorganic substance, and then the waste water in the tank 6 is returned to the tank 2. Hence, microbes in the tank 2 are activated, too, so that the waste water is conditioned into the state that the microbes contained in said waste water are activated, i.e. suited to the decomposition of organic substance in said waste water. Consequently, the stabilization of the waste water disposal system can be contrived.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a biological treatment method for wastewater containing organic substances, such as fishery processing wastewater, human and livestock processing wastewater, and agricultural processing wastewater.

In a patent application filed at the same time as the filing of this invention, the inventors of this invention proposed a useful biological treatment method to replace the conventional biological treatment of wastewater containing organic substances using the activated sludge method. The characteristics of this biological treatment method will be explained based on the flow sheets shown in Figs. , a wastewater treatment circulation system that sequentially sends the sludge to the separator 4 and returns the sludge separated by the separator 4 to the strong air tank 3, and in the anaerobic tank 2, the adjustment I
The wastewater sent from II 1 is aerated with an amount of aeration to maintain a state in which anaerobic bacteria including facultative anaerobic bacteria living in the anaerobic tank 2 can grow. Air tank 3
In this case, wastewater containing anaerobic sludge containing facultative anaerobic bacteria is supplied from the anaerobic tank 2 and aerobic sludge containing aerobic bacteria including the Zoog Ioea genus is returned from the separation device 4. Zooglare (Z
After the aerobic bacteria including the genus oogl-oea are activated, the wastewater is sent to the separator 4' to separate the wastewater and sludge, and the separated sludge is sent to the inlet of the strong air tank 3. In addition to the above-mentioned characteristics, the sludge returned to the inlet of the air tank 3 from the separation-W is separated from the remaining □ sludge and discharged to the outside of the wastewater treatment circulation system. The air is passed through the reaeration tank 5.

Compared to the conventional activated sludge method, this biological treatment method can treat wastewater regardless of its concentration, so there is no need to dilute the wastewater, and as a result, It is possible to downsize the lif' equipment, simplify operation management, and require less aeration, and significantly reduce running costs.
The characteristics are nurturing.

However, if there are sudden changes in the pollutant components or concentration of wastewater, changes in weather conditions, or other physical and chemical changes, the survival conditions for bacteria in the wastewater treatment circulation system may be affected by these factors. As a result, smooth wastewater treatment cannot be carried out due to fluctuations in the flow rate, and as a result, a large amount of effort is required to stabilize the wastewater treatment fA'j ring 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 are as follows: □ A part of the ml water in the anaerobic tank is activated in the anaerobic tank according to the invention proposed at the same time. FJ was taken out and the 7qC/N ratio was adjusted and inorganic substances were added, and the same conditions as in the anaerobic tank were used in this activation tank. '$il! After t1'5'', the wastewater in the activation tank is returned to the anaerobic tank.

Flowchart 1-1 of this invention method shown in FIGS. 3 to 6.
The explanation will be based on.

First, the first invention will be explained based on the flow sheets shown in FIGS. 3 and 4.

This first method of the invention sends wastewater from a regulating tank 1 through an anaerobic tank 2 and a strong aeration tank 3 to a separation device 4, and returns the sludge produced in the separation device 4 to a strong aeration tank 3. The anaerobic tank 2 is activated by the activation tank 6 installed in the anaerobic tank 2.
This activates wastewater within the area.

Among the bacteria that act in this wastewater treatment circulation system, the main aerobic bacteria are the Zoogloea genus.
Other yeasts are also included. Anaerobic bacteria include facultative anaerobic bacteria that have some aerobic properties, such as lactic acid bacteria (La
ctobacillus) genus, Pediococcus (1
'ediococcus) Streptococcus (S-
trep tococcus), Bacillus (Bacillus)
Any anaerobic microorganism containing bacteria belonging to the genus Illus or the like may be used.

These aerobic bacteria and anaerobic bacteria are previously introduced into the anaerobic tank 2 before the operation of the wastewater treatment circulation system starts (thereafter, those that have grown naturally in the anaerobic tank 2 are used).

Wastewater includes fishery processing wastewater, raw livestock wastewater, agricultural processing wastewater,
Any type of wastewater containing other organic substances can be treated by the method of the present invention.

This wastewater is first collected in the adjustment tank 1, where operations such as equalizing the liquid, adding nutrients, adjusting the pH, etc. are performed as necessary. After the water has been retained for a predetermined period of time, the water is usually continuously supplied to the anaerobic tank 2 in fixed amounts, but in the case of batch processing, water is supplied all at once.

In the aeration tank 2, wastewater sent from the adjustment tank 1 is stored and aerated and agitated by air sent from the air blower TA7. This aeration is to provide a small amount of dissolved oxygen in the wastewater in order to activate facultative anaerobic bacteria, which are the main group of anaerobic bacteria in the aeration tank 2, and to weakly stir the wastewater. It has been found empirically and experimentally that weak aeration is sufficient.

Specifically, weak aeration, usually less than one-tenth of the aeration amount in the aeration tank, is sufficient for the conventional activated sludge method, and if a larger amount is used, the wastewater will not be sufficiently agitated. Although this is done, facultative anaerobic bacteria become inactive and anaerobic sludge is not produced, which goes against the purpose of aeration of the main tank 2. By performing aeration that meets these conditions, anaerobic bacteria including facultative anaerobic bacteria proliferate in the anaerobic tank 2, and the wastewater containing anaerobic sludge of anaerobic bacteria is strengthened. The wastewater in the anaerobic tank 2, which is supplied to the activation tank 3 and inhabited by facultative anaerobic bacteria, is guided by the pump 8 to the activation tank 6, where the C/N While adjusting the ratio and adding inorganic substances, aeration and agitation under the same conditions in the anaerobic tank 2 is sent from the blower 7 for a predetermined period of time. After this activation, the waste water in the tank 6 is returned to the anaerobic tank 2. The capacity of this activation tank 6 may normally be about 1/100 to 1/10 of the capacity of the anaerobic tank 2. Further, the C/N ratio is appropriately selected and adjusted within the range of 1 to 25 depending on the pollutant components of the wastewater.

This adjustment of the C/N ratio is performed to activate the anaerobic bacteria contained in the wastewater and increase their growth rate, but if the C/N ratio is high, it can be lowered by adding nitrogen components such as urea. If the C/N ratio is low, a carbon component such as waste molasses is added to increase it.

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 accelerate their growth rate. A solution containing about 50% of other necessary salts is added in an amount of about 1/300 to 1/7 (7) of the volume of the activation tank 6. Waste water in activation tank 6! ,,-The retention time is 10 times the division time of facultative anaerobic bacteria present in the wastewater.
The standard is about twice as much, specifically about 2 hours and 30 hours,
Extend or shorten the residence time as necessary depending on wastewater conditions or other reasons. The anaerobic water in the anaerobic tank 2 is supplied to the activation tank 6 by supplying the above-mentioned predetermined amount all at once and carrying out the above-mentioned treatment. The so-called batch processing that returns to tank 2 is
Although standard, constant amounts may be fed continuously in cases where the wastewater composition is not particularly suitable for anaerobic bacterial growth.

The wastewater treated in the activation tank 6 is 1. As mentioned above, the anaerobic bacteria are activated and are in the most suitable state for promoting microbial decomposition of organic matter, so by returning this to the anaerobic tank 2, the wastewater in the anaerobic tank 2 can also be Similar to the wastewater returned from the activated cyclone, it is in a state suitable for promoting microbial decomposition of organic matter, that is, a state in which the anaerobic bacteria in the wastewater are activated. This activation tank 6
The batch treatment of the wastewater may be performed continuously depending on the wastewater composition G, but it may be performed continuously only when there is a possibility that the treatment system will not be able to operate smoothly due to changes in the conditions of the wastewater. You may also do so. The temperature of the wastewater in the activation tank 6 is τ±lO with respect to the temperature of the wastewater in the anaerobic tank 2.
The temperature range is preferably within 30°C, and most preferably 30°C or higher and 32°C or lower.

Incidentally, depending on the nature of the wastewater or various circumstances, the regulating tank 1 and the anaerobic tank 2 may be combined into one regulating anaerobic tank that also serves as the two tanks 1.2. However, this is within the technical scope of the method of this invention.

At the inlet of the strong aerobic tank 3, the anaerobic sludge wastewater containing anaerobic bacteria, including facultative anaerobic bacteria, supplied from the anaerobic tank 2 and the aerobic bacteria returned from the separation device 4 are active. aerobic sludge is mixed in. The amounts of both are equal in terms of solids concentration, or the amount of aerobic sludge is higher.

These two different types of sludge have contradictory physical and chemical properties, and among these contradictory physical and chemical properties, aerobic sludge due to Coulomb force and van der Waals force, and anaerobic sludge Due to synergistic effects such as increased affinity with the sludge, the formation of a type of polymer bonding reaction between the two sludges, and the adhesive force due to the mucous membrane formed by aerobic bacteria, the bonding between the two sludges increases. A strong cohesive force is provided. Due to this strong cohesive force and the effect of incorporating dissolved components into the progress of aggregation,
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 with the same or similar pollutant components have a strong cohesive force as described above, but on the other hand, sludge produced from wastewater with different pollutant components Between the aerobic sludge and anaerobic sludge,
It has been experimentally found that no cohesive force occurs. This indicates that the aggregation reaction is not simply due to Coulomb force or van der Waals force, but also the existence of a certain kind of inter-polymer bonding reaction.

In this way, the wastewater containing the sludge, in which both the anaerobic bacteria and the aerobic bacteria newly generated in the □ Zooglare (Zoog Io)
It is brought to an aerobic state in which the bacteria including the genus ea) are activated, and then sent to the separation device 4. The strong air in the strong air tank 3 facilitates separation of wastewater and sludge in the separation device 4, and further promotes purification of the wastewater.

In this separation device 4, in order to further enhance the flocculating effect of anaerobic sludge and aerobic sludge, it is preferable to use an inorganic flocculant, particularly an iron-based flocculant.

In this way, the newly generated sludge is separated from the liquid part in the separator 4, mixed with the wastewater supplied from the anaerobic tank 2 as described above by a pump not shown, and then sent in the required amount to the strong aerobic tank 3. It will be sent back. Since aerobic bacteria including the genus Zooglaea are grown while circulating between the strong air tank 3 and the separation device 4, the ones added before the start of operation are used as is.9 The separation device 4 is not limited to the sedimentation tank type □ shown in FIG. 2, but also includes a separation device 811 based on other mechanical or physical means.

The required amount of the remaining contaminant returned to the strong air tank 3 is separated into solid and liquid by the sludge diluter 9, and the solid part is discharged to the outside of the wastewater treatment circulation system, and the liquid part is separated. Device 4
'T: Together with the remaining liquid portion from which the sludge has been removed, it is discharged as treated water to the outside of this wastewater treatment circulation system. At this time, if the contaminant concentration in these liquid parts exceeds the regulation value,
After the necessary treatment is carried out in the higher-order treatment step 10 and the pollution concentration is kept below the regulation value ε, it is discharged as treated water.

This higher-level treatment process 10 includes methods such as sand filtration and biological treatment such as conventional activated sludge method.

When the higher-order treatment process IO is based on biological treatment such as activated sludge method, all of the generated sludge can be treated within the same wastewater treatment circulation system by returning it to the forced air tank 3.

In addition, in the aeration tank 2, anaerobic bacteria including facultative anaerobic bacteria that were added to the width of the aeration tank 2 before the start of operation are growing naturally, but the concentration of wastewater flowing into the anaerobic tank 2 is low. If the conditions for natural growth of facultative anaerobic bacteria cannot be satisfied for reasons such as this, as shown in Figure 4, a part of the sludge is separated from the liquid part in the separator 4 and separated into anaerobic sludge. Tank 2
You may also send it back to By returning this sludge, environmental conditions suitable for the growth of anaerobic bacteria are satisfied.

Next, the second invention will be explained below based on the flow sheets shown in FIGS. 5 and 6.

This second invention is different from the first invention described based on FIGS. Since the other points are the same as the first invention except that the gas is returned to the inlet of the air tank 3, a detailed explanation of the common parts will be omitted and only the different points will be explained.

In Fig. 5, the sludge separated by the separator 4 is in an aerobic sludge state in which aerobic bacteria are activated by strong aeration in the strong aeration tank 3 in the previous step, but the pollution concentration of the raw wastewater is If the wastewater from the anaerobic tank 2 and the sludge returned from the separator 4 are difficult to coagulate sufficiently, such as when the sludge is relatively thin, the aerobic sludge separated by the separator 4 may be recycled. By further aerobizing the water in the aeration tank 5, the flocculation can be carried out efficiently and the purification effect of the wastewater can be promoted.

Figure 6 is a flow sheet for a case where a part of the sludge that has been made more aerobic in the reaeration tank 5 is also returned to the anaerobic tank 2, and the environmental conditions suitable for the growth of anaerobic bacteria in the anaerobic tank 2 are not met. in,
This corresponds to FIG. 4 in the first invention.

In addition, in the above two systems, when anaerobic bacteria including Lactobacillus bacteria, which is a type of facultative anaerobic bacteria, is used, due to the growth of putrefactive bacteria under anaerobic conditions in anaerobic tank 2. The progress of putrefaction is inhibited, and therefore the occurrence of putrefaction weeks is prevented.In addition, even if the solid part from which the liquid part has been removed by the sludge dewatering machine 9 is left as it is, the progress of putrefaction is delayed, and therefore secondary damage caused by sludge is prevented. Does not cause pollution.

In the above explanation, an example has been described in which aeration and agitation in the anaerobic tank 2, strong aeration tank 3, reaeration tank 5, and activation tank 6 are performed by supplying air from the blower 7, but other means can also be used. Of course, aeration and stirring may also be used.

As is clear from the above description, the method of the present invention allows wastewater to be divided into a regulating tank I, an anaerobic tank 2, a strong air tank 3, and a dividing device 4.
A wastewater treatment circulation system in which the sludge separated by the separator 4 is returned to the inlet of the strong aeration tank 3, or the sludge separated by the separator 4 in the system is sent to the reaeration tank 5. In the wastewater treatment circulation system that returns the water to the strong aerobic tank 3 via Since the bacteria are activated and then returned to the original anaerobic tank 2, the bacteria in the anaerobic tank 2 are also activated, and the microorganisms contained in the wastewater are activated.
That is, since the wastewater is adjusted to a state suitable for decomposing organic matter, the wastewater treatment system can be stabilized. Therefore, when the pollutant components or pollutant concentration of wastewater suddenly change, changes in weather conditions and other physicochemical changes can be adequately coped with, and smooth and efficient wastewater treatment can be performed.

[Brief explanation of the drawing]

FIGS. 1 and 2 are flow sheets of a wastewater treatment circulation system without an activation tank, FIGS. 3 and 4 are examples of the flow sheets of the first invention, and FIGS. 5 and 6 are Examples of flow sheets of the second invention are shown. 1-adjustment tank, 2--anaerobic tank, 3-strong-pulsation tank, 4--separation device, 5-1--reaeration tank, 6-activation tank. Patent applicant: Yasutoshi Okubo, attorney: Mitsuhiko Watanabe Procedural amendment (method) March 7, 1980 Commissioner of the Patent Office Mr. Kazuo Wakasugi Name: Biological treatment method for wastewater containing organic substances 3, relationship with cases requiring amendments Patent applicant address: 3-3-23-1302, Nishi-Shinjuku, Shinjuku-ku, Tokyo Name: Yasushi Okubo 4, Agent: 530 Phone number: Osaka 06 (361) 3B
31 Address: 2-21 Tayu-cho, Kita-ku, Osaka City, February 2, 1982 (k 1st 6th, 7th City Council's Statement of Amendment Procedures (voluntary) 1982 s /1;, 7. Mr. Kazuo Wakasugi, Commissioner of the Japan Patent Office on the 1st, 1981 Patent Application No. 1 (i 3b I) 9'+2
, Name of the invention Method for chemical treatment of wastewater containing organic sejn 3, ? l
! Make an i-correct - 77 Relationship to the case Patent applicant name Yasushi Okubo 4, agent 530 Telephone Osaka +16 (3Cil)
3831 Address Kita-ku, Osaka-shi FA: B-cho 2-21 New Prairie Building 705'1 (1) Claims column (2) Detailed explanation of the invention column 6 of the specification, amendments Contents +11 As per the appendix in the scope of claims.゛(2) Detailed Description of the Invention Column ■ On page 6, line 10 of the specification, "made of steel" is amended to "adjustment". □■ Specification page 8, line 6 □ r (Pediococcus) J and “Stref0
Toco,. Insert "genus," between "cus". ■Details 1, page 7, line 13 □Enter 1"
is corrected to "put it in". ■ Correct "Aeration Tank 2" to "Anaerobic Tank 2" on page 8, line 6 of the specification. ■ Correct "Aeration tank 2" on page 8, line 8 of the specification to "Anaerobic tank 2". ■ In the specification, page 1, line 13, "bacterial growth" is corrected to "growth of one bacterium." ■ Is "activated" on page 11, line 18 of the specification changed to "activated"? lli+14ru. □ ・ ■ On page 12, line 5 of the specification, amend it to "Ninikeru/JfT ni Oriru." ■ Correct “higher-order processing process” on page 14, line 11 of the specification to “higher-order processing = C process” - [Phase] Change “held” to “held” on page 14, line 13 of the specification. Corrected to ``. - Correct "Higher-order processing process" on page 14, line 14 of the specification to "1 higher-order processing step." @ On page 14, line 16 of the specification, "higher-order processing process" is corrected to "higher-order processing step." 0 In the specification, page 14, line 20, "in the aeration tank 2" □ is corrected to "in the anaerobic tank 2". [Phase] "The aeration tank 2" on page 14, line 20 of the specification is corrected to "the anaerobic tank 2". [Phase] On page 16, line 15 of the specification, "at 1 yuan" is corrected to "under". [Phase] Specification, page 16, line 16 [Correct putrefaction week-1 to [putrefaction odor j]. @r! IJl+att page 17, line 2, example 1,
” should be corrected to “for example”. 7. Attachment A/List of J documents (11 Claims (amendment) 1 or more lu request 1'L [(輔f) 1. Waste water containing organic substances is transferred from the adjustment tank to the anaerobic tank to the strong air A wastewater treatment circulation system that sequentially sends sludge to a tank and a separation device, and returns sludge separated by the separation device to a strong air tank,
In the anaerobic tank, the wastewater sent from the adjustment tank is aerated at an amount of aeration that maintains a state in which anaerobic bacteria including facultative anaerobic bacteria living in the anaerobic tank can proliferate. In the strong aeration tank, wastewater containing anaerobic sludge containing facultative anaerobic bacteria is supplied from the aeration tank and zoogloea is returned from the separation device.
A state where aerobic bacteria including Zooglaea (Zoog I oea) genus are activated by strongly aerating the wastewater that has been mixed with aerobic sludge containing aerobic bacteria including the genus Zoog I oea and coagulated to produce new sludge. After that, this wastewater is sent to a separator to separate wastewater and sludge, and the 141 tons of sludge is returned to the inlet of the above-mentioned strong air tank, and the remaining sludge and separated wastewater are sent out of the wastewater treatment circulation system. Furthermore, a part of the wastewater in the anaerobic tank is taken out to an activation tank, the C/N ratio is adjusted and inorganic substances are added, and in this activation tank, aeration and stirring are carried out under the same conditions as in the anaerobic tank. After doing
A biological treatment method for wastewater containing organic substances, characterized in that wastewater in an activation tank is returned to an anaerobic tank. 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. Send the wastewater containing organic substances from the IB treatment tank to the anaerobic tank, strong aeration tank, and separation device in order, and the sludge separated by the separation device to the strong aeration tank via the re-aeration tank. The anaerobic tank is a wastewater treatment circulation system in which the wastewater sent from the adjustment tank is in a state where anaerobic bacteria including facultative anaerobic 1flfl bacteria living in the anaerobic tank can proliferate. In the strong aeration tank, the wastewater containing the anaerobic sludge containing facultative anaerobic bacteria supplied from the anaerobic tank is mixed with the wastewater supplied from the anaerobic tank. Zooglare returned via reaeration tank
The aerobic sludge containing aerobic bacteria including the genus C. loea was mixed and coagulated to generate new sludge, and the wastewater was strongly aerated, and the aerobic bacteria including the genus Zoogloea were activated. After the condition, this wastewater is treated as F4at.
The separated sludge is supplied to the reaeration tank and separated from the remaining sludge = fL wastewater is discharged outside the wastewater treatment circulation system, and the wastewater in the anaerobic tank is After taking out a part of the mixture into an activation tank, adjusting the C/N ratio and adding inorganic substances, and performing aeration and stirring in the activation tank under the same conditions as those in the anaerobic tank,
A biological treatment method for wastewater containing organic substances, characterized by returning wastewater in an activation tank to an anaerobic tank. 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.

Claims (1)

[Scope of Claims] A raw water treatment circulation system that sequentially sends sludge to a strong air tank and a separator, and returns sludge separated by the separator to the strong air tank, in which the sludge is The wastewater sent from the tank is aerated to maintain conditions in which anaerobic I ([lT@), which contains facultative anaerobic bacteria living in the tank (also known as C), can proliferate. In the above-mentioned case, the wastewater containing anaerobic sludge containing facultative anaerobic bacteria was collected from the aeration tank and the aerobic bacteria containing the Zoogloea genus was returned. Aerobic sludge is mixed and flocculated to produce new sludge, which is then strongly aerated to produce Zooglare.
After the IJ asperoforming bacteria including the genus Ioea') are activated, the wastewater is separated into sludge using a separator, and the separated sludge is returned to the inlet of the strong air tank. The residual sludge and the separated wastewater are discharged outside the wastewater treatment circulation system, and a part of the wastewater in the anaerobic tank (1) is taken into an activation tank, and then C, / After adjusting the N ratio and adding inorganic substances? After this activation, the onion is stirred under the same conditions as in the anaerobic tank in the anaerobic tank, and then the wastewater in the activation tank is returned to the oxidation tank. 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. Wastewater containing organic substances is transferred from the adjustment tank to the anaerobic tank and the strong aerobic tank1. A wastewater treatment circulation system in which the sludge is sequentially sent to the separating and paving equipment, and the sludge separated by the separator is returned to the anaerobic tank via the re-aeration tank, and in the anaerobic tank, The saw wastewater sent from the adjustment tank is aerated with an aeration amount suitable for maintaining a state in which anaerobic bacteria including facultative anaerobic bacteria living in the anaerobic tank 11J proliferate and reach one mass. In the aeration tank, wastewater containing anaerobic sludge containing facultative anaerobic bacteria supplied from the aeration tank and Zooglaia (Zooglare) returned from the separator mentioned above via the re-aeration tank.
Aerobic sludge containing aerobic bacteria including the genus Zooglaea (Ioea) is mixed and flocculated to generate new sludge, and the wastewater is strongly aerated to activate aerobic bacteria including the genus Zooglaia (Zooz Ioea). After that, this wastewater is sent to a separation device to separate wastewater and sludge, and this separated sludge is supplied to a reaeration tank, and the remaining sludge and separated wastewater are discharged outside the wastewater treatment circulation system, and further, A part of the wastewater in the anaerobic tank is taken out to an activation tank, the CZN ratio is adjusted and inorganic substances are added, and in this activation tank, aeration and stirring are performed under the same conditions as in the anaerobic tank, and then activated. A biological treatment method for wastewater containing organic substances, characterized by returning wastewater in a tank to an anaerobic tank. 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.