JPH04161295A - Abnormal phenomenon-preventing agent of activated sludge and method for preventing abnormal phenomenon of activated sludge - Google Patents

Abstract

PURPOSE:To prevent the bulking phenomenon of activated sludge due to filamentous fungi by adding a quaternary salt of an alkyleneimine polymer having a specific intrinsic viscosity to activated sludge containing filamintous fungi or actinomyces or activated sludge-containing waste water. CONSTITUTION:A quaternary alkyleneimine polymer whose intrinsic viscosity [eta]is below 0.08dl/g (measured in an 1N KBr solution at 25 deg.C) is added to activated sludge containing at least filamentous fungi or actinomyces or to activated sludge-containing waste water in an amount of 0.05-25 pts.wt. per 100 pts.wt. of a dry activated sludge solid. As a result, specific filamentous fungi bringing about an abnormal phenomenon such as a bulking phenomenon corresponding to the change of recent urban sewage or actiomyces forming a foamed layer to the part of an aeration or sedimentation tank at the time of the aeration treatment of activated sludge, becoming scum or bringing about bulking, can specifically be killed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention deals with the swelling phenomenon of activated sludge, that is, bulking.
The present invention relates to an agent for preventing abnormal phenomena such as the formation of a foam layer or scum in the upper part of an aeration tank or settling tank that occurs during aeration of activated sludge, and a method for preventing abnormal phenomena.

[Conventional technology]

Activated sludge method is one of the biological methods used for wastewater treatment. This method involves blowing air into wastewater containing organic matter to propagate microorganisms, thereby removing the sludge and
In other words, it utilizes the properties of activated sludge, and because activated sludge forms highly adsorbent flocs whose specific gravity is greater than that of water (for example, it is said to be around 1.003), it is difficult to leave it still. This method takes advantage of the phenomenon in which clear treated water is left behind after sedimentation. The settled activated sludge is reused as return sludge.

Sewage, human waste and various organic industrial wastewaters are commonly treated with activated sludge. During treatment using this method, changes occur in the flow rate of inflowing wastewater, changes in organic matter in inflowing wastewater, and changes in the types of microorganisms such as various molds, filamentous bacteria, and actinomycetes that grow in the sewer pipes. It is known that the microbial flora in activated sludge changes in response to changes in

For example, if the influent raw water has a low solids content and a high sludge retention time (SRT), Nocardia amara x
(Nocardia amarae) breeds in large quantities in activated sludge, producing surface-active mycolic acids, promoting the stabilization of air bubbles, and causing air bubbles containing sludge to accumulate in the upper part of the aeration tank and final settling tank. , released. The effluent itself may also foam, damaging its appearance.

In addition, when filamentous bacteria and actinomycetes increase, sludge expands,
Sedimentation worsens, the sludge rises close to the water surface, the amount of sludge overflow increases, the treatment capacity decreases, and in some cases, the so-called bulking phenomenon occurs, which makes treatment impossible. When this phenomenon occurs, the sludge becomes whitish, very light, and difficult to settle, and it also has air bubbles attached to it, and a foam layer with sludge attached to the top of the aeration tank can sometimes reach tens of centimeters or more. and accumulate. Moreover, the sludge that adheres to the air bubbles accumulated at the top of the aeration tank or the sludge that adheres to the air bubbles that overflow from the aeration tank rots and gives off a bad odor, and the sludge in the air bubbles that accumulates in the aeration tank eventually settles. If the treated water is discharged from the tank together with the treated water, it may cause poor appearance due to foaming, BOD, and CO.
D may increase and cause environmental sludge. As an indicator of whether activated sludge is functioning normally, S
There is a VI (Sludge Volume Index) value, which is the volume in ml that is occupied by 1 g of activated sludge after the activated sludge suspension is allowed to stand for 30 minutes (JIS B9944). The SVI value of activated sludge that exhibits normal functions is 50 to 150, especially 10.
Although it is less than 0, it can be as high as 300 to 800 in activated sludge that has undergone bulking. Furthermore, the increase in SH value caused by actinomycetes is about 200 to 300, and this may cause sewage outflow due to the rise of the sludge interface.

It is not easy to restore the function of activated sludge that has generated foaming, scum, or bulking, and in the worst case, it becomes necessary to replace the sludge. It would be necessary to stop using the product until the product has become accustomed to the product, which would have a serious impact on the factory's production plan.

Even in public sewage treatment plants, BOD removal efficiency decreases due to the outflow of expanded sludge and a decrease in sludge concentration, which can lead to water pollution and become a major social problem.

In general final treatment plants for urban sewage, most bulking occurs due to filamentous bacteria, and Sphaerocilus and 8eggiatoa have traditionally been considered to be representative microorganisms that cause this (according to the Japan Sewage Works Association). Magazine, Vol. 22, No. 252, pp. 2-12 (1985)). By the way, as a result of the recent development of sewage systems, rainwater and domestic wastewater, etc., have come to be treated separately, and as a result, bulking occurs when urban sewage, which is domestic wastewater, is treated using the activated sludge method. It is presumed that changes have also occurred in filamentous bacteria.

As a method for preventing the occurrence of bulking of activated sludge, Japanese Patent Publication No. 5B-14274 and Japanese Patent Publication No. 58-1
A method described in Japanese Patent No. 4275 and the like has been proposed.

The method described in Japanese Patent Publication No. 58-14274 is a method in which one or more dithiocarbamates having a specific structure are dissolved in water and added to activated sludge. However, this method is only applicable when the cause of bulking is abnormal growth of filamentous fungi, and is not effective when there are other causes.

In addition, when using this method, it takes more than 4 days, and in some cases more than 10 days, for the activated sludge to become effective, even if the degree of damage to the activated sludge is relatively minor, and in addition, a large amount is added every day. The downside is that you have to keep going.

The method described in Japanese Patent Publication No. Sho 58-14275 contains one or two amino acids such as valine, leucine, isoleucine, glutamic acid, phenylalanine, and tyrosine.
A composition containing at least one species as an active ingredient is added to activated sludge. When using this method, a composition containing these active ingredients is added to the influent wastewater at a concentration of 0.
It is necessary to add continuously for more than 3 hours at a high level of 5 to 5 kg/m', and it takes 24 hours to become effective.
It has the disadvantage that it requires more time.

The bulking phenomenon of activated sludge is caused by 5 phaerotilu
It is based on the abnormal growth of filamentous bacteria and fungi such as S (genus Sphaerocyllus), 7iiothrix (genus Thiothrix), ^spergillus (genus Aspergillus), and Penicillium (genus Penicillium).
Depending on the season and nutritional status, a highly viscous jelly-like substance is generated in activated sludge, which makes it difficult for the sludge to settle, and may also exhibit a bulking phenomenon. In the latter case, it is said to be effective to add ZnC]□ or a cationic acrylamide polymer flocculant to the wastewater. However, according to the inventor's experiments, activated sludge tends to contain air bubbles in an aeration tank, etc., and activated sludge that contains air bubbles has an extremely low ability to treat wastewater, making it difficult to prevent bulking. It was found that there was no significant effect.

In addition, attempts have been made to restore the normal microbial flora without relying on the addition of chemicals, for example, using only operating conditions such as adding a large amount of suspended solids (SS) without using anaerobic or aerobic treatment or an initial settling tank. However, type 021N, type 1701. Type 1702. No satisfactory solution has yet been proposed for bulking caused by overgrowth of at least one type of filamentous bacteria such as Type 0041, Microthrix, and Parvicella.

Furthermore, to prevent foaming, scum, and bulking caused by actinomycetes, a method is known in which an antifoaming agent, such as a carboxylic acid ester compound, is mixed with shower water and sprayed in the aeration tank and final settling tank. It is being According to experiments conducted by the present inventors, it has been found that this method of mixing and spraying an antifoaming agent does not suppress foaming, but only destroys the formed bubble layer, and has almost no effect.

Furthermore, in JP-A-49-3468, the limiting viscosity [η
] (It has been disclosed that polyalkyleneimine quaternary salts having NaBr1 of 0.1 to 1.0 at 30°C are effective as anti-bulking agents. It has been found that although grade salt can temporarily lower SVI, it is not sustainable.

[Problem that the invention seeks to solve]

In response to recent changes in urban sewage, the present invention is designed to eliminate specific filamentous bacteria that cause abnormal phenomena such as bulking, or to form a foam layer on the top of the aeration tank or sedimentation tank during aeration treatment of activated sludge. The objective is to specifically kill actinomycetes that cause oxidation and bulking, and to provide a particularly long-lasting and sterilizing agent and method for preventing abnormal phenomena in activated sludge. .

[Means to solve the problem]

The activated sludge abnormal phenomenon prevention agent of the present invention is an agent for preventing activated sludge bulking phenomenon caused by at least one type of filamentous bacteria or activated sludge abnormal phenomenon caused by actinomycetes, and has an intrinsic viscosity [η] of 0. 08dl/g (25℃, 1N KB
(measured in an aqueous solution).
It is characterized by being a grade salt.

Further, the method for preventing abnormal phenomena in activated sludge of the present invention provides that activated sludge or activated sludge-containing wastewater containing at least one type of filamentous bacteria or actinomycetes has an intrinsic viscosity [η] of 0.08.
dl/g (measured at 25°C with a 1N KBr aqueous solution), 0.05 to 25 parts by weight of an alkyleneimine polymer quaternary salt is added to 100 parts by weight of dry solid content of activated sludge. shall be.

[Target activated sludge]

The activated sludge targeted by the anti-bulking agent of the present invention is one in which bulking or the like is caused by at least one type of filamentous bacteria or actinomycetes.

As filamentous bacteria, type 021N, type 0041
° Type 1701, Type 1702, and Microthrix.

Examples include Parvicella and the like. Type 021N, Type 0
041, and Microthrix, Parvicella filamentous bacteria, D, H, Eikelboom: Frog, W
ater, Tech.

Vol. 8, No. 6, pp. 153-161 (1977). In addition, type 17o1 and type 1702 filamentous bacteria are P, F, Storm and Ori, Jenking: Journal WPCF,
Vol. 56, No. 5, pp. 459-499 (1984
It is defined in 2013).

If these filamentous bacteria need to be isolated, they can be easily obtained from activated sludge of sewage.

The abnormal phenomenon prevention agent of the present invention is applied to activated sludge that has signs of bulking caused by these filamentous bacteria, or that has undergone bulking, or wastewater containing activated sludge.

Further, the abnormal phenomenon prevention agent of the present invention is intended for activated sludge that causes foaming, scum, or bulking in treated water after sedimentation by actinomycetes. Actinomycetes in activated sludge include Nocardia and Amarae.
rdia, amarae), Rhodococcus rhodochrous
) etc. If it is necessary to isolate such actinomycetes, they can be easily obtained from the foam tank, scum, and sludge accumulated in the upper layer of the aeration tank of activated sludge from sewage.

[Quaternary salt of alkylene imine polymer] The chemical substance of the abnormal phenomenon preventing agent of the present invention is a quaternary salt of an alkylene imine polymer, and is represented by the following formula.

χ- -(R-N H,) , - (where R is an alkylene group, preferably a carbon number of 1 to 6
straight or branched alkylene group. A plurality of R's may be the same or different.

X is halogen, such as bromine, chlorine, iodine.

n represents an integer, and the intrinsic viscosity [η] measured in an IN-KBr aqueous solution at 25° C. satisfies 0.08 or less. ) Furthermore, the quaternary salt of the alkylene imine polymer in the present invention does not have a completely linear structure as shown above, but may have a branched structure.

Specific examples of such quaternary salts of alkyleneimine polymers include quaternary salts of ethyleneimine polymers, quaternary salts of propyleneimine polymers, quaternary salts of trimethyleneimine polymers, and tetramethyleneimine polymers. quaternary salts of hexamethyleneimine polymers, copolymers thereof, and mixtures of at least two thereof. Among these, ethyleneimine polymer hydrochloride is particularly preferred for economic reasons.

Hydrochloride salts of ethyleneimine polymers are generally obtained by adding hydrochloric acid to ethyleneimine polymers. Ethyleneimine polymers are generally obtained by open polymerization of ethyleneimine using a cationic catalyst, but can also be obtained by reaction of ethylene dihalide with ethylenediamine or ammonia, condensation reaction of ethanolamine, and the like.

The degree of quaternization is preferably 100%, but it may not be completely quaternized.

The quaternary salt of the alkylene imine polymer thus obtained is dissolved in a KBr aqueous solution of IN (normal) and measured, and its molecular weight is determined by the calculated intrinsic viscosity [η] at 25°C. be able to.

In the present invention, [η] is preferably 0.08 or less. When the intrinsic viscosity [η] is greater than 0.08, the activated sludge envelops filamentous bacteria and actinomycetes and forms large flocs, resulting in poor sedimentation of the sludge for several days. Afterwards, abnormal phenomena such as bulking due to filamentous bacteria and foaming scum due to actinomycetes occur again, which is not preferable.

The quaternary salt of the alkylene imine polymer is preferably dissolved in a solvent (usually water) and used as an aqueous solution to prevent abnormal phenomena in activated sludge, and this is usually the case.

[Activated sludge abnormal phenomenon prevention method]

The target activated sludge to be prevented from abnormal phenomena contains the above-mentioned actinomycetes and filamentous bacteria, and the method for preventing abnormal phenomena in activated sludge by adding a chemical according to the present invention, except for changing the treatment conditions accordingly. is the same as the conventional method.

Specifically, a quaternary salt of an alkylene imine polymer is made into an aqueous solution with an appropriate concentration, for example, 0.1 to 10% by weight, and this aqueous solution is prepared by one of the following methods or a combination of two or more methods. Good to add.

(1) Method of mixing with inflowing wastewater and sending it to an aeration tank.

(2) Q! A method of adding directly to an air tank or settling tank where activated sludge is bulking or foaming.

(3) Method of adding to returned sludge.

If the amount of the quaternary salt of the alkylene imine polymer used is too small, the purpose of the present invention will not be achieved, and if it is too large, actinomycetes and filamentous bacteria will be rapidly destroyed and the treated water will suddenly become cloudy. This is not preferable because it may cause the COD of the treated water to increase in some cases, or be washed out of the system together with the wastewater. The amount used is 0.0 per 100 weight of dry solid content of activated sludge.
It is preferable to select it within the range of 5 parts by weight to 25 parts by weight. More preferably, the amount is in the range of 0.1 parts by weight to 10 parts by weight.

When a quaternary salt of an alkylene imine polymer is added once within the above range to activated sludge, no increase in the SVI value is observed for one month or more. Thereafter, if signs of an increase in the SVI value are observed, at that point the alkyleneimine polymer
It is preferable to add the grade salt within the above range.

[Action and effect of invention]

By using the quaternary salt of the alkylene imine polymer in the present invention, which has a low intrinsic viscosity of 0.08 or less, it has bactericidal properties compared to the alkylene imine polymer, and can be used in activated sludge. It was found that the adsorption capacity was high and the anti-bulking effect was long-lasting.

That is, according to the present invention, it is possible to specifically prevent bulking of activated sludge caused by at least one type of filamentous bacteria and abnormal phenomena of activated sludge caused by actinomycetes, and prevent abnormal proliferation of filamentous bacteria and actinomycetes. If the quaternary salt of this alkyleneimine polymer is added at the point when signs of an increase in the SVI value or foaming phenomenon are observed, or at the point at which the SVI value increases, the further increase in the SVI value can be substantially suppressed. The SVI value can be maintained at or below the original level without causing any damage. In addition, the foaming phenomenon is quickly resolved, and the good condition can be maintained.

Especially for filamentous bacteria, the filamentous form is destroyed,
Although the product is discharged from the treatment tank together with the treated water, almost no increase in BOD is observed, so that good treated water can be provided.

Furthermore, since the abnormal phenomenon prevention agent of the present invention has a long-lasting effect even after one addition, the present invention is extremely useful in managing activated sludge processes.

In addition to these effects, the present invention also has the following effects.

(1) Simply adding it to the activated sludge treatment system can suppress the increase in SVI in a short time.

(2) The activated sludge in the aeration tank does not expand, the sedimentation volume is reduced, the activated sludge concentration is kept high, and the effect of removing BOD and COD can be significantly increased.

(3) The concentration rate of activated sludge also increases significantly in the settling tank.

(4) The concentration rate of activated sludge is significantly increased even in the case of the s line type.

The quaternary salt of the alkyleneimine polymer in the present invention has a remarkable effect on destroying filamentous bacteria or actinomycetes in activated sludge, and preventing abnormal phenomena such as bulking of activated sludge caused by the filamentous bacteria. This is what we discovered.

Hereinafter, the present invention will be specifically explained with reference to Examples.

Examples 1 and Comparative Examples 1 to 2 in which the activated sludge contains filamentous bacteria and Example 2 and Comparative Examples 3 to 41 in which the activated sludge contains actinomycetes will be described. The intrinsic viscosity of the quaternary salt of the alkylene imine polymer used in the following Examples and Comparative Examples is the value at 25° C. measured with an IN (normal) KBr aqueous solution.

(Preparation of abnormal phenomenon prevention agent) Preparation of present invention samples A, B, C and comparative sample.

Each ethyleneimine polymer (trade name of Nippon Shokubai Chemical Industry ■ Epomine, grade 5P-018, 5P-200, 5P
5P-018, 5P-200 and 5P-200 with a concentration of 50 wt. Ethyleneimine polymer hydrochloride of 5P-300 (IN-
KBr aqueous solution with intrinsic viscosity [η] of 0.04, 0.05, and 07 dl/g at 25° C. was used as the present invention sample A, B, and C, respectively, and P with a concentration of 20% by weight was used.
-1000 ethyleneimine polymer hydrochloride (IN-KB
In r aqueous solution, the intrinsic viscosity [η] at 25°C is 0.16d.
l/g) was used as a comparison sample.

[Example 1] Monthly average 50. OQOm'/day, B[]D is 2[10m
At a public sewage treatment plant (standard activated sludge method) that processes urban sewerage wastewater of 1 g/1, an aeration tank (MLSS = 1
．． 500mg/I! ) settled sludge volume index (SVI
) is 50Dmj! /g, and the separability of treated water and sludge in the final settling tank deteriorated significantly.

When the sludge in the aeration tank and settling tank of this treatment plant was observed using a phase contrast microscope, it was found that there were type 0041 and type 1702 bacteria between the flocs, rather than floc-forming bacteria.
A larger volume of filamentous bacteria was observed.

The activated sludge from this treatment plant was put into a small activated sludge treatment model with an aeration tank capacity of 31 and a sedimentation tank capacity of 11, simulating an actual treatment plant, and the amount of dissolved oxygen in the aeration tank was adjusted to IB/1 to 3 mg/
B[
It was continuously added so that the ID negative load was about 0.5Kg/Kg MLSS/day, and the return sludge rate was set to 50%, and the operation was continued.

In the return sludge line of this small model, samples A, B,
and C0.8g (equivalent to 8.9 parts by weight per 100 weight of dry solid content of activated sludge) was diluted 100 times with water,
Continuous addition was carried out for 48 hours.

1 day, 3 days, and 10 days after the start of continuous drug addition, respectively.
The SVI in the aeration tank and the COD of the treated water were measured after 1 day, 20 days and 30 days.

The results are shown in Table 1.

[Comparative Example 1] The sludge from the public treatment plant of Example 1 was placed in a small activated sludge model similar to that of Example 1, and the model was continuously operated under the operating conditions of Example 1.

To the return sludge line of this small model, 2 g of comparative sample D (8.9 parts by weight per 100 parts by weight of dried sludge solid content of activated sludge) was diluted 100 times with water and continuously added for 48 hours.

Although the sedimentation properties of activated sludge in the settling tank temporarily improved,
Three days after the start of continuous addition, the sedimentation properties of the sludge deteriorated again, so 3 g of a comparative sample (equivalent to 13.3 parts by weight per 100 parts by weight of dry solids of activated sludge) was added to 24
It was added continuously for an hour.

SVT and COD in the aeration tank sludge were measured in the same manner as in Example 1.

The results are shown in Table 1.

[Comparative Example 2] The sludge from the public treatment plant of Example 1 was placed in a small activated sludge model in the same manner as in Example 1, and the model was continuously operated under the same operating conditions as in Example 1.

Into the return sludge line of this small model, add 2.0g of sodium hypochlorite aqueous solution (available chlorine concentration: 5%) for 7 days (2.2g per 100 parts by weight of dry solids of activated sludge).
(equivalent to 2 parts by weight) was added continuously for 10 days.

SVI and COD in the aeration tank sludge were measured in the same manner as in Example 1.

The results are shown in Table 1.

(Left below) Table 1 and microscopic observation of the activated sludge in the aeration tank revealed the following.

(1) In Comparative Example 2, the addition of sodium hypochlorite destroyed not only filamentous bacteria but also useful floc-forming bacteria, making the treated water extremely cloudy and reducing CO2 in the treated water.
This resulted in an increase in O value.

In Comparative Example 1, the intrinsic viscosity [η] was 0.16 dl/
By adding a comparative sample of -g of S of the activated sludge,
The VI value decreased, but when the addition was stopped, the activated sludge S
When the VI value increased and the addition was repeated, the sludge trapped air bubbles and floated to the surface in the aeration tank, resulting in poor conditions.

According to the present invention, the amount of added chemicals is small compared to the comparative example, the SVI value decreases quickly after the addition of the chemicals, the sedimentation properties of activated sludge are significantly improved, and the effect is long lasting.

(2) When the present invention is used, compared to each comparative example, filamentous bacteria in the sludge present in the aeration tank and settling tank are extremely reduced, and the activated sludge forms solid flocs.

(3) When using the present invention, filamentous bacteria are destroyed and flowed out, but the COO value of the treated water is 20 mg/R or less and is good as treated water.

[Example 2] Monthly average 5,000 m'/day, BOD 200 mg/day
At the public sewage treatment plant that processes separated urban sewage wastewater in A, the aeration tank (sludge MLSS is 2.200 mg/1
) has an SVI value of about 250 m1/g, but the foamed scum that has turned brown due to the entrapment of sludge remains in the upper part of the aeration tank, and the foamed scum continues to flow into the final settling tank. Ta.

When the sludge in the aeration tank and settling tank of this treatment plant was subjected to Durham staining and observed under an optical microscope, many typical actinomycetes attached to floc-forming bacteria were observed in the sludge. When the foaming scum was observed under a microscope, more actinomycetes were observed than floc-forming bacteria.

This activated sludge from a public sewage treatment plant was put into a small model of an activated sludge treatment model with an aeration tank capacity of 1 and a sedimentation tank capacity of 11, assuming an actual public sewage treatment plant.
The inflow raw water from the above public sewage treatment plant was adjusted to 3mg/f, and the inflow raw water from the above public sewage treatment plant was continuously added to the BOD load of about 0.5Kg/Kg MLSS/day, and the return sludge rate was adjusted to 30
It was operated continuously as %.

Samples A and B of the present invention were installed in the return sludge line of this small model.
and C1,2g (equivalent to 9.1 parts by weight based on 100 parts by weight of dry solid content of activated sludge) were diluted 100 times and continuously added over 48 hours.

1 day, 3 days, 10 days, 2 days after the start of continuous drug addition
After 0 days and 30 days, the amount of foamed scum at the interface of the sedimentation tank, the SVI of the sludge in the aeration tank, and the COD of the treated water were measured. However, the amount of foamed scum at the interface of the sedimentation tank is the ratio of the foamed scum to the volume during the start of continuous addition of the above-mentioned sample of the present invention, that is, the volume of foamed scum before the start of continuous addition to 1
It is expressed as a percentage with 00%. The results are shown in Table 2.

[Comparative Example 3] The activated sludge containing actinomycetes from Example 2 was placed in a small model of activated sludge treatment similar to Example 2, and continuously operated under the same operating conditions as described in Example 2.

Comparative sample D5 was installed in the return sludge line in this small model.
．． 0 g was diluted 100 times with water and continuously added over 48 hours.

From the start of continuous addition of chemicals, the amount of foamed scum at the interface of the sedimentation tank, the SVI of the sludge in the aeration tank, and the COD of the treated water were measured in the same manner as in Example 2.

The results are shown in Table 2.

[Comparative Example 4] Using the same activated sludge and operating conditions as in Example 2, an antifoaming agent was added from the top of the aeration tank. As an antifoaming agent, a special paraffin ester compound (Minecon C manufactured by Daito Pharmaceutical Co., Ltd.) was diluted with water to 0.1% by weight and continuously added from the top of the aeration tank at a rate of 8 ml/min for 5 days. (The amount added per day corresponds to 175 parts by weight per 100 parts by weight of dry solid content of activated sludge).

From the start of continuous addition of the antifoaming agent, the amount of foamed scum at the settling tank interface, 5v11 of sludge in the aeration tank, and COD of the treated water were measured in the same manner as in Example 2.

The results are shown in Table 2.

(Margin below) The following was found from Table 2 and microscopic observation of the activated sludge.

(1) Compared to Comparative Example 4, when the additive is added in a small amount, the foaming scum caused by actinomycetes is rapidly reduced, and the SVI value of the sludge is further reduced, and the sedimentation property of the activated sludge is significantly reduced. improvement and long-lasting effects.

On the other hand, in Comparative Example 4, the foamed scum at the interface between the aeration tank and the settling tank was temporarily reduced by adding the antifoaming agent, but when the addition was stopped, the foamed scum accumulated at the interface between the aeration tank and the settling tank again. .

In addition, in Comparative Example 3, 3
The foaming scum at the interface between the aeration tank and the settling tank decreased for several days, but after that, the foaming scum accumulated at the interface between the aeration tank and the settling tank again, returning to the state before the start of continuous addition.

(2) When the present invention is used, actinomycetes are extremely reduced in the sludge present in the aeration tank and sedimentation tank compared to Comparative Example 3.4, and the activated sludge forms solid flocs.

(3) When using the present invention, actinomycetes are destroyed and exist in the treated water and flow out, but the COO value of the treated water is 20 mg.
/R or less, which is good as treated water.

Claims (2)

[Claims] (1) An agent for preventing the bulking phenomenon of activated sludge caused by at least one type of filamentous bacteria or the abnormal phenomenon of activated sludge caused by actinomycetes, which has an intrinsic viscosity [η] of 0.08 dl/g
An agent for preventing abnormal phenomena in activated sludge, characterized in that it is a quaternary salt of an alkylene imine polymer, which has a temperature lower than 25° C. (measured with a 1N KBr aqueous solution at 25° C.). (2) Activated sludge or activated sludge-containing wastewater containing at least one type of filamentous bacteria or actinomycetes has an intrinsic viscosity [
η] is less than 0.08 dl/g (measured at 25°C with a 1N KBr aqueous solution),
0.05 to 100 parts by weight of dry solid content of activated sludge
A method for preventing abnormal phenomena in activated sludge, characterized by adding 25 parts by weight.