JPH0312293A - Abnormal phenomenon preventing agent and method of activated sludge - Google Patents

Abstract

PURPOSE:To eliminate the generation of the bulking phenomenon of activated sludge due to filamentous bacteria by preparing an abnormal phenomenon preventing agent of activated sludge from a water-soluble polymer formed by the reaction of monoalkylamine with epihalohidrin. CONSTITUTION:A 20-70% aqueous solution of monoalkylamine or, according to circumstanes, monoalkylamine and dialkylamine is charged in a hermetically closed reactor and the atmosphere in the reactor is substituted with nitrogen gas. Next, epihalohidrin is added while the temp. in the reactor is controlled to about 30-100 deg.C and reacted with said amine to obtain a water-soluble polymer. An aqueous solution containing 1-10wt.% of this water-soluble polymer is prepared and inflow waste water is mixed with this aqueous solution to be introduced into an aeration tank. By this method, the bulking phenomenon of activated sludge caused by filamentous bacteria such as TyPe 021N can be prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to the expansion phenomenon of activated sludge, that is, bulking (
The present invention relates to an agent for preventing abnormal phenomena such as bulking phenomenon, formation of a foam layer in the upper part of an aeration tank or settling tank, and scum formation during aeration treatment of activated sludge, and a method for preventing the same.

More specifically, the present invention provides Type 021N, Type 1
701, type 1702, type 0041 and Micr
The present invention relates to an abnormal phenomenon prevention agent and an abnormal phenomenon prevention method that effectively prevent abnormal phenomena caused by specific miscellaneous bacteria including at least one kind of filamentous bacteria belonging to the group oLhrix Parvicella (Microthrix, Parvicella), and actinomycetes.

[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 produces highly adsorbent flocs whose specific gravity is greater than that of water (for example, it is said to be around 1.003), it is This method takes advantage of the phenomenon in which clear treated water is left behind when it settles. The settled activated sludge is reused as return sludge.

Sewage, human waste and various organic industrial wastewaters are commonly treated by activated lη mud. 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 actinobacteria that grow in sewer pipes. It is known that the microbial flora in activated sludge changes in response to these changes.

For example, if the solid content in the influent raw water is low and the sludge retention time (SRT) is large, Nocardia and Amarae (Nocardia a+l1are) will be abundant in the activated sludge. 1, the sludge multiplies, produces surface-active mycolic acid, promotes bubble stabilization, accumulates sludge-containing bubbles in the upper part of the aeration tank and final settling tank, and is discharged. The effluent itself may also foam, damaging its appearance. Also filamentous bacteria,
When actinomycetes increase, sludge expands and settles poorly,
The sludge rises to near the water surface, the amount of sludge overflowing increases, the treatment capacity decreases, and in some cases, the so-called bulking phenomenon occurs, where treatment becomes impossible. When this phenomenon occurs, the sludge becomes whitish, very light, and difficult to settle.

In particular, when actinomycetes increase, sludge adheres to air bubbles, and a foam tank with sludge adhering to it sometimes accumulates at the top of the aeration tank, reaching a length of several tens of centimeters or more. 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 of the treated water and BOD.
, COD may increase and cause environmental pollution.

One indicator of whether or not activated sludge is functioning properly is SVI (Sludge Volume I).
ndex, sludge index) value. This SVI is expressed as the volume occupied by 1 g of activated sludge in 30 minutes of settling.

The SVI value of activated sludge that exhibits normal a-ability is 50 to 15.
0, especially 100 or less, but activated sludge that has undergone bulking can have as many as 300 to 800. In addition, the increase in SVI value caused by actinomycetes is 200 to 300.
This may cause sewage to flow out 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, the BOD removal efficiency decreases due to the outflow of expanded sludge and a decrease in sludge concentration, which can lead to environmental pollution and become a major social problem.

Methods for preventing bulking of activated sludge are disclosed in Japanese Patent Publication No. 58-14274 and Japanese Patent Publication No. 58-14275.
The method described in the above publication 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 only targets cases where the cause of bulking is abnormal growth of filamentous fungi, and is not effective if there are other causes. Even if the degree of damage to the activated sludge is relatively slight, it requires 4 days or more, in some cases 10 days or more, and has the disadvantage that a large amount must be continuously added every day.

The method described in Japanese Patent Publication No. Sho 58-14275 contains one or two amino acids such as valine, leucine, isosucine, glutamic acid, phenylalanine, and 1,000 rosin in wastewater.
A composition containing at least one species as an active ingredient is added to activated sludge.

When using this method, it is necessary to continuously add a composition containing these active ingredients to the inflowing wastewater at a high level of 0.5 to 5 kg/m' for more than 3 hours, and the effect is It has the disadvantage that it takes more than 24 hours to exhibit its properties.

The bulking phenomenon of activated sludge is 5 phaer.

tilus, Th1othrix
(Thiotrix genus), Aspergillus (Aspergillus genus), Penicillium (Penicillium genus), and other filamentous bacteria and fungi can overgrow. Depending on the season and nutritional status, a highly viscous jelly-like substance may be formed in activated sludge. This causes the sludge to become difficult to settle (and may exhibit bulking phenomenon. In the latter case, it is effective to add ZnCl2 or a cationic acrylamide-based polymer flocculant to the wastewater. However, according to the inventor's experiments, activated sludge tends to contain air bubbles in aeration tanks, etc., and activated sludge containing air bubbles has an extremely poor ability to treat wastewater. It was found that there was no significant effect on preventing bulking.

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. Yes, but type 021N1 type 170h type 1
No satisfactory method has yet been proposed for bulking caused by overgrowth of at least one type of filamentous bacteria such as 702, type 0041, Microthrix, and Parvicella.

In addition, 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. According to experiments conducted by the present inventors, it was found that this method of mixing and dispersing an antifoaming agent does not suppress foaming, but only destroys the bubble tank that has been formed, and has almost no effect.

In general final treatment plants for urban sewage, most bulking occurs due to filamentous bacteria, and Sphaerochilus and Beggiatoa 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, with the recent development of sewerage systems, rainwater and domestic wastewater, etc. have come to be separated and treated. It is assumed that changes have also occurred in the filamentous bacteria that cause bulking when urban sewage, such as domestic wastewater, is treated by the activated sludge method.

[Problem to be solved by the invention]

In response to recent changes in urban sewage, the present invention is designed to prevent specific filamentous bacteria that cause abnormal phenomena such as bulking, or to form a foam layer on the top of an aeration tank or settling tank during aeration treatment of activated sludge. The purpose of the present invention is to specifically kill actinomycetes that cause scum and bulking, and to provide an agent for preventing abnormal phenomena in activated sludge made of a specific water-soluble polymer, and a method for preventing the same. .

[Means to solve the problem]

That is, the activated sludge bulking inhibitor of the present invention is type 021N, type 1701, type 1702, type 0041, and Microthrix Parvic.
el Ia (Microthrix.

an abnormal phenomenon of activated sludge caused by at least one kind of filamentous bacteria consisting of the group Parvicella) or a bulking inhibitor of activated sludge caused by actinomycetes, which is a monoalkylamine and shrimp herrohydrin, or a monoalkylamine and dialkylamine mixture. It is characterized by consisting of a water-soluble polymer obtained by the reaction of shrimp and shrimp halosiderin.

Furthermore, the method for preventing abnormal phenomena in activated sludge of the present invention is based on type 0
21 N, type 1701, type 1702, type 0
041, and MicrothrixParvicell
A monoalkylamine and epihalohydrin, or a monoalkylamine and dialkylamine mixture and epihalohydrin are added to activated sludge or activated sludge-containing wastewater containing at least one type of filamentous bacteria of the group A (Microthrix, Parvicella) or actinomycetes. It is characterized in that 0.05 to 25 parts by weight of the water-soluble polymer obtained by the reaction with the activated sludge is added to 100 parts by weight of the dry solid content of the activated sludge.

(Target activated sludge) Activated sludge targeted by the bulking inhibitor of the present invention is type 021N, type 1701, type 1702, type 0041, and microslick.

Bulking is caused by at least one kind of filamentous bacteria from the group consisting of Parvicella or actinomycetes.

Type 021N, Type 0041 and Microlink,
The filamentous bacterium of Parvicella is D., H. Eilelboo.
m; Prog, Water Tech, Volume 8,
No. 6, pp. 153-161 (1977). Also, type 1701, type 17
The filamentous bacteria of 02 are P, F, Storm and Je.
nkins:JournaI WPCF, Volume 56,
No. 5, pp. 449-459 (1984). The abnormal phenomenon preventive agent of the present invention is added to activated sludge that has signs of bulking caused by these filamentous bacteria or that has undergone bulking, or to wastewater containing activated sludge.

If it is necessary to isolate these filamentous bacteria, they can be easily obtained from the activated sludge of these sewages.

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 due to actinomycetes.

Actinomycetes in activated sludge include Nocardia an+are, Rhodococcus, and Rhodococcus rho.
dochrous) etc. If it is necessary to isolate such actinomycetes, they can be easily obtained from the foam layer, scum, and sludge accumulated in the upper part of the aeration tank of activated sludge from sewage.

(Water-Soluble Polymer) The abnormal phenomenon preventing agent of the present invention is a water-soluble polymer whose chemical substance is obtained by reacting a monoalkylamine and an epihalohydrin, or a mixture of a monoalkylamine and a dialkylamine and an epihalohydrin.

In addition, in water-soluble cationic polymers obtained by the reaction of monoalkylamine and dialkylamine mixtures with epihalohydrin, those in which the counter ion (halogen derived from epihalohydrin) is replaced with other anions, and the corresponding hydroxylated shall include things.

Monoalkylamines, which are raw materials for such polymers, are represented by the general formula, dialkylamines are represented by the general formula, and epihalohydrins are represented by the general formula %. It is appropriate.

Specific examples of such monoalkylamines include methylamine, ethylamine, propylamine, etc.
Specific examples of dialkylamine include dimethylamine, diethylamine, dipropylamine, methylethylamine, methylpropylamine, and ethylpropylamine.

When monoalkylamine and dialkylamine are used together, the molar ratio of dialkylamine to the total amount of amine is 0.
．． Up to 9 can be added.

These amines can be used in combination within and between the above groups.

In epihalohydrin, the halogens are fluorine, chlorine,
Bromine or iodine are generally of interest, but epichlorohydrin is preferred, at least for economic reasons.

In order to react monoalkylamine and epihalohydrin as described above, the number of moles of monoalkylamine (if dialkylamine is used together, the total number of moles of monoalkylamine and dialkylamine) and the number of moles of epihalohydrin must be approximately the same. Using an equimolar closed reaction vessel with a stirrer, the internal temperature of the reaction vessel was adjusted to 30% under an inert gas atmosphere.
It is preferable to set it in the range of ~100°C.

More specifically, a 20 to 70% aqueous solution of a monoalkylamine or a dialkylamine is charged into a closed reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, etc., and the atmosphere inside the vessel is adjusted. It is preferable to add epihalohydrin continuously or batchwise while substituting with nitrogen gas and adjusting the internal temperature of the reaction vessel to a predetermined temperature while stirring.

The water-soluble polymer thus obtained is further processed,
It is clear from the foregoing that the halogen (derived from epihalohydrin) as a counterion can be replaced by another anion, or that the counterion can be removed to convert the polymer into a hydroxide.

The water-soluble polymer obtained as above is 2 mol/1
Intrinsic viscosity [η
], the molecular weight can be determined. In the method of the present invention, [η] is 04 d 1 / g or less, more preferably 0.3 dj! /g or less is desirable.

If [η] is too small, adsorption to activated sludge will decrease,
This is not preferable because the durability of the bulking prevention effect decreases.

Moreover, if [η] is larger than 0.4 dl/g, the activated sludge will trap filamentous bacteria and actinomycetes to form large flocs, and the settling properties of the sludge will only improve temporarily, lasting several days. Afterwards, bulking is likely to occur again in the case of filamentous bacteria, and foaming and scum of the treated water will occur again in the case of actinomycetes, which is undesirable.

When the solvent is an organic solvent other than water, the water-soluble polymer thus obtained is preferably used as a solid by removing it, and then diluting this with water to form an aqueous solution. Further, it is preferable and usual to use a solution produced as an aqueous solution as it is or after diluting or concentrating as necessary.

(Method for preventing abnormal phenomena in activated lη mud) The target activated sludge for which abnormal phenomena should be prevented contains the above-mentioned actinomycetes and specific filamentous bacteria, and the treatment conditions must be changed accordingly. Other than this, the method of preventing bulking of activated sludge by adding chemicals according to the present invention is essentially the same as the conventional method.

Specifically, the water-soluble polymer is added to an appropriate concentration, e.g.
An aqueous solution having a concentration of approximately 1% by weight may be prepared, and this aqueous solution may be added according to any of the following methods or a combination of two or more of these methods.

■ A method of mixing with the inflowing wastewater and sending it to the aeration tank.

■ Method of adding directly to an aeration tank or settling tank where bulking of activated sludge is occurring ■ Method of adding to returned sludge The amount of water-soluble polymer used is This is not desirable as the purpose will not be achieved (on the contrary, if the amount is too high, actinomycetes and filamentous bacteria will be severely destroyed, the treated water will suddenly become cloudy, or it will be washed out of the system with wastewater, and in some cases This is not preferable as it may cause an increase in the COD of the treated water, and the amount used is preferably selected within the range of 0.05 to 25 parts by weight per 100 parts by weight of dry solid content of activated sludge. is in the range of 0.1 to 10 parts by weight.

When a water-soluble polymer is added once within the above range to activated sludge, no increase in SVI is observed for one month or more. Thereafter, if signs of an increase in the SVI value are observed, it is advisable to add the water-soluble polymer within the above range at that point.

[Action and effect of invention]

According to the invention, type 021N, type 1701, type 1702, type 0041 and Microthrix,
Bulking of activated sludge caused by at least one type of filamentous bacteria from the group consisting of Parvicella and abnormal phenomena of activated sludge caused by actinomycetes are specifically prevented. That is, according to the water-soluble polymer of the present invention, the water-soluble polymer can be removed at the time when signs of an increase in svr value or foaming phenomenon due to abnormal proliferation of filamentous bacteria and actinobacteria are observed, or after the svr value has increased. Addition of the polymer can quickly maintain the svr value at or below the original level without substantial further increase in the svr value.

In particular, the filamentous form of filamentous bacteria is destroyed, and the products flow out of the treatment tank together with the treated water, but the BO
Since almost no increase in D is observed, good treated water can be provided. Furthermore, the drug of the present invention lasts for a long time after being added once.

Therefore, if the present invention is implemented, seedling raising will be extremely effective in terms of activated sludge process control.

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

(2) When using the method of the present invention, the increase in SVI of activated sludge can be suppressed in a short time by simply adding the water-soluble polymer described above to the activated sludge treatment system.

(2) When the method of the present invention is used, the activated sludge in the aeration tank does not expand, the sedimentation volume is reduced, the activated sludge concentration is kept high, and the BOD removal effect can be significantly increased.

(2) When the method of the present invention is used, the sedimentation and separation of activated sludge becomes easier even in the sedimentation tank.

(2) When the method of the present invention is used, the concentration rate of activated sludge becomes significantly low even in the thickening tank.

The water-soluble polymer used in the present invention is known per se as a sedimentation accelerator, but this polymer destroys specific filamentous bacteria and actinomycetes, and the bulking phenomenon of activated sludge caused by this. This work was discovered to prevent such abnormal phenomena.

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

A case will be described in which the activated sludge contains filamentous bacteria according to Examples 1 to 4 and Comparative Examples 1 and 2, and a case where the activated lη mud contains actinomycetes according to Examples 5 to 8 and Comparative Example 3.

[Example 1] Monthly average 3000 m”/day, BOD 20 Qmg/l,
At a public sewage treatment plant that processes separated urban sewerage wastewater with suspended solids (SS) of 120 mg/l, the settled sludge volume index (SV[) of the aeration tank exceeds 500, and the dry sludge concentration of returned sludge (MLSS) became less than 2000 mg/f, and the MLSS of the aeration tank also became less than 1000 mgz1, 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, and when it was stained with Durham and observed using an optical microscope, it was found that rather than floc-forming bacteria, there were filamentous types of type 021N between the flocs. A larger volume of bacteria was observed. The γη mud from the public sewage treatment plant mentioned above was put into a small model of activated sludge treatment with an aeration tank capacity of 31 and a sedimentation tank capacity of 1++, which simulates an actual public sewage treatment plant, and the amount of dissolved oxygen in the aeration tank was calculated. The inflow raw water of the above public sewage treatment plant is adjusted to 1 to 2 mg/β, and the BOD load is 0.4 Kg/Kg.
The sludge was continuously added at a rate of about MLSS/day, and the sludge was continuously operated at a sludge return rate of 50%.

In this small model of activated sludge treatment, epichlorohydrin was added to a 50% methylamine aqueous solution while maintaining the reaction temperature at 90°C until the molar ratio of 50% methylamine aqueous solution and epichlorohydrin was 1:1. Stir and mix, and dilute 0.6 g of the resulting mixed reaction composition (a composition with an intrinsic viscosity [η] of 0.07 dll/H measured with a 2 mol/l KBr aqueous solution) 100 times with tap water. It was continuously added to the return sludge line for 48 hours.

One day after the start of continuous addition of the above mixed reaction composition, 3
After 1 day, 10 days, 20 days, and 30 days, the SVI of the sludge in the aeration tank and the COD of the treated water were measured.

The results are shown in Table 1.

[Example 2] Activated sludge containing type 021N of Example 1 was placed in a small model of activated sludge treatment similar to Example 1, and the activated sludge of Example 1 was
Continuous operation was carried out under the same conditions as the amount of dissolved oxygen in the aeration tank, the amount of added raw water added, and the activated sludge return rate described in .

In this small model of activated sludge treatment, the molar ratio was set in advance to i:o,
The molar ratio of a 50% aqueous solution of methylamine-dimethylamine mixture adjusted at a ratio of 5 to epichlorohydrin is 1
: Add epichlorohydrin to a 50% aqueous solution of methylamine-dimethylamine mixture while maintaining the reaction temperature at 80°C until the ratio is 1.05, and mix with stirring.
0.6 g of the obtained mixed reaction composition (composition with an official viscosity [η] of O and t4d17'g measured with a 2 mol/1 KBr aqueous solution) was transferred to the return sludge line while being diluted 100 times with tap water. was continuously added for 48 hours.

From the start of continuous addition of the above mixed reaction composition, the sludge and SVI in the aeration tank and the COD of the treated water were measured in the same manner as in Example 1.

The results are shown in Table 1.

[Example 3] Monthly average 12000m3/day, BOD 200mg/l,
At a public sewage plant that processes separated urban sewerage wastewater with a suspended solids content (SS) of 50 mg/l, the settled sludge volume index (SVI) of the aeration tank exceeds 400, and the dry sludge concentration of the returned sludge (MLSS) became less than 2500 mg/L, and the MLSS of the aeration tank also became less than 1300 mg/IL, 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 at this treatment plant was subjected to Durham staining and observed using a phase contrast microscope, it was found that the presence of type 1701 bacteria rather than floc-forming bacteria was observed between the flocs in the sludge. A large number of filamentous bacteria of type 1702, type 0041, Microthrysoxus, and Parvicella were observed.

The above activated sludge was placed in a small activated sludge treatment model similar to that in Example 1, and continuous operation was performed under the same conditions as the amount of dissolved oxygen in the aeration tank, the amount of raw water added, and the sludge return rate described in Example 1. did.

In this small model of activated sludge treatment, the same mixed reaction composition of methylamine and epichlorohydrin as in Example 1 was used.
5 g was continuously added for 48 hours while diluting 100 times with tap water.

From the start of continuous addition of the above mixed reaction composition, 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 1.

The results are shown in Table 1.

[Example 4] Type 1701, type 1702, type 0 of Example 3
Activated sludge in which 041, Microthurisox, and Parvicella are present was placed in a small model of activated sludge treatment similar to that in Example 1, and the amount of dissolved oxygen in the aeration tank, the amount of inflow raw water added, and the activity described in Example 1 were evaluated. Continuous operation was performed under the same conditions as the sludge return rate.

A small model of this activated sludge treatment was prepared using the same methylamine-dimethylamine mixture as in Example 2 (with a molar ratio of 1:O,S).
A mixed reaction composition of 0.0% and epichlorohydrin.
7 g was diluted 100 times with tap water and continuously added to the return sludge line for 48 hours.

From the start of the continuous addition of the above mixed reaction composition, the svr of the sludge in the aeration tank and the COD of the treated water were measured in the same manner as in Example 1.

The results are shown in Table 1.

[Comparative Example 1] In Example 1, under the same activated sludge and operating conditions, 0.8 g of sodium hypochlorite aqueous solution (available chlorine concentration 5%) was added to the return sludge line without adding the reaction composition of the present invention.
/day for 7 days, the filamentous bacteria contained in the sludge began to decrease, but the SVI value was 400, which was still not sufficient, so 0.8 g of sodium hypochlorite was added. /day for 7 days.

From the start of continuous addition of sodium hypochlorite, 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 1.
was measured.

The results are shown in Table 1.

[Comparative Example 2] In Example 3, using the same activated sludge and operating conditions, cationic polyacrylamide (Clifix CP627 manufactured by Kurita Water Industries, Ltd.) was added to the return sludge line without adding the reaction composition of the present invention. 0.2 for sludge in aeration tank
When the returned lη mud siline was added continuously for 3 days at a rate of 1.0 g/day, the SVI value decreased to 1 when containing filamentous bacteria.
It became 60. However, after the addition was stopped, the sedimentation properties gradually worsened, and the SVI value reached 400 after 5 days.
Furthermore, it was added continuously for 3 days at a rate of 0.2 g/day.

From the start of continuous addition of cationic polyacrylamide, the S of the sludge in the aeration tank and the C of the treated water were added in the same manner as in Example 1.
OD was measured.

The results are shown in Table 1.

(Margins below) The following is clear from Table 1 and microscopic observation of the activated sludge in the aeration tank.

(2) In Comparative Example 1, not only filamentous bacteria but also useful floc-forming bacteria were destroyed by the addition of hypochlorous acid, and the treated water became extremely cloudy.

In Comparative Example 2, the SVI value of activated sludge temporarily decreased due to the addition of cationic polyacrylamide, but when the addition was stopped, the SVI value of activated sludge increased again.
Furthermore, the SVI value of the activated sludge decreased, but when the addition was stopped, the SVI value of the activated sludge rose again, and if the addition was repeated, the sludge would float up in the aeration tank, trapping air bubbles, and become in good condition. There wasn't.

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

(2) In the case of the present invention, the number of filamentous bacteria in the sludge present in the aeration tank and settling tank is reduced at the ends of the sludge compared to each comparative example, and the activated sludge forms solid flocs.

(2) When using the present invention, filamentous bacteria are destroyed and flowed out, but the COD value of the treated water is 20 mg/I! It is good as treated water.

(Example 5) Monthly average 5000 m3/day, BOD 20 Qmg/l,
At a public sewage treatment plant that processes separated urban sewerage wastewater with a suspended solid content (S It emits an odor of about 10,000
The foam layer, which had turned brown due to enveloping sludge, remained for about 20 cm to 20 cm without disappearing.

This foam layer overflows from the top of the aeration tank and pollutes the surrounding area, the overflowing material rots and becomes a source of bad odors, and even worse, the foam layer containing sludge flows into the final settling tank. The BOD and COD values of the effluent water, which were discharged together with the treated water, exceeded 20 mg/l. In addition, the dry sludge concentration (MLSS) of the returned sludge from this treatment plant is 3500mg/
J, MLSS in the aeration tank is 1600 mg/(
It was l.

When the sludge in the aeration tank and settling tank of this treatment plant was Duram stained and observed under an optical microscope, many typical actinomycetes attached to floc-forming bacteria were observed in and around the sludge. The sludge contains actinomycetes, and the sludge adheres to the mycolic acid secreted by actinomycetes and their filamentous forms, reducing the density of the sludge and making it difficult to settle.

The sludge from the public sewage treatment plant mentioned above was put into a small model of activated sludge treatment with an aeration tank capacity of 31 and a sedimentation tank capacity of 1β, assuming an actual public sewage treatment plant, and the amount of dissolved oxygen in the aeration tank was reduced to 1. ~2m g / 12, and the inflow raw water of the above public sewage treatment plant has a BOD load of 0.4Kg/Kg ML.
The sludge was continuously added on a schedule of about SS/day, and the sludge was continuously operated at a sludge return rate of 25%.

In this small model of activated sludge treatment, epichlorohydrin was added to a 50% methylamine aqueous solution while maintaining the reaction temperature at 90°C until the molar ratio of 50% methylamine aqueous solution and epichlorohydrin was 1:1. The mixed reaction composition obtained by stirring and mixing (2 mol/l KBr
0.8 g of a composition having an intrinsic viscosity [η] of 0.07 dβ/g as measured in an aqueous solution was continuously added to the return sludge line for 48 hours while being diluted 100 times with tap water.

One day after the start of continuous addition of the above mixed reaction composition, 3
After 1 day, 10 days, 20 days, and 30 days, the amount of foamed scum at the aeration tank interface, the SV I of lη mud in the aeration tank, and the COD of the treated water were measured. However, the amount of foamed scum at the aeration tank interface is expressed as a percentage of the foamed scum accumulation at mJ at the start of continuous addition of the above reaction mixture (the accumulation of foamed scum before the start of continuous addition is taken as 100%). did.

The results are shown in Table 2.

[Example 6] The activated sludge containing actinomycetes from Example 5 was placed in a small model of the same activated sludge treatment as in Example 5, and the amount of dissolved oxygen in the aeration tank and the inflow raw water as described in Example 5 were measured. Continuous operation was carried out under the same conditions as the addition amount and activated sludge return rate.

In this small model of activated sludge treatment, epichlorohydrin was added to a 50% ethylamine aqueous solution while maintaining the reaction temperature at 80°C until the molar ratio of the 50% ethylamine aqueous solution to epichlorohydrin became 11.05. The mixed reaction composition obtained by stirring and mixing (intrinsic viscosity [η] measured with a 2 mol/l KBr aqueous solution was 0.14 dj
'/g composition) was continuously added to the return sludge line for 48 hours while diluting 100 times with tap water.

i! of the above mixed reaction composition! One day after the start of continuous addition,
After 3 days, 10 days of wheat, 20 days and 30 days, the amount of foamed scum at the aeration tank interface, 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 5. Second result
Shown in the table.

[Example 7] The activated sludge containing actinomycetes from Example 5 was placed in a small model of the same activated sludge treatment as in Example 5, and the amount of dissolved oxygen in the aeration tank and the inflow raw water as described in Example 5 were measured. Continuous operation was carried out under the same conditions as the addition amount and activated sludge return rate.

In this small model of activated sludge treatment, the molar ratio was set to 1:0.
The molar ratio of a 50% aqueous solution of methylamine-dimethylamine mixture adjusted at a ratio of 5 to epichlorohydrin is 1
A mixed reaction composition obtained by adding epichlorohydrin to a 50% aqueous solution of a methylamine-dimethylamine mixture and stirring and mixing while maintaining the reaction temperature at 90°C until a ratio of 2 mol/1 was obtained. 0.7 g of a composition having an intrinsic viscosity [η] of Oll 0 d lt / g as measured with a KBr aqueous solution of 0.7 g was continuously added to the return sludge line for 48 hours while being diluted 100 times with tap water.

One day after the start of continuous addition of the above mixed reaction composition, 3
After 1 day, 10 days, 20 days, and 30 days, the amount of foamed scum at the aeration tank interface, 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 5. The results are shown in Table 2.

[Example 8] The activated sludge containing actinomycetes from Example 5 was placed in a small model of the same activated sludge treatment as in Example 5, and the amount of dissolved oxygen in the aeration tank and the inflow raw water as described in Actual side 5 were measured. Continuous operation was carried out under the same conditions as the addition amount and activated sludge return rate.

In this small model of active lη mud treatment, the molar ratio was set in advance as t:O.
, S, and epichlorohydrin in a 50% aqueous solution of the ethylamine-dimethylamine mixture until the molar ratio of the epichlorohydrin to the 50% aqueous solution of the ethylamine-dimethylamine mixture adjusted to the proportions of S was 1:1. While maintaining the temperature at 90°C, add, stir and mix,
The obtained mixed reaction composition (composition with an intrinsic viscosity [η] of 0.13 dl/g measured with a 2 mol/l KBr aqueous solution)
0.7 g was diluted 100 times with tap water and continuously added to the return sludge line for 48 hours.

One day after the start of continuous addition of the above mixed reaction composition, 3
After 1 day, 10 days, 20 days, and 30 days, the amount of foamed scum at the aeration tank interface, the SVl of the sludge in the aeration tank, and the COD of the treated water were measured in the same manner as in Example 5. The results are shown in Table 2.

[Comparative Example 3] In Example 5, with the same activated lη mud and operating conditions, the antifoam agent was added from the top of the aeration tank without adding the reaction composition of the present invention. The antifoaming agent is a special paraffin ester compound (Daito Pharmaceutical Co., Ltd.'s Mikonene, C) mixed with 0.1 ml of water.
It was diluted to % by weight and added at a rate of 8 tel/min from the top of the aeration tank for 3 days. An antifoaming effect was observed where the antifoaming agent was applied, but a sufficient effect was not obtained, so an additional 8 mj! Additions were made at a rate of 1/min for 5 days.

One day after the start of continuous addition of the above reaction mixture composition, 3
After 1 day, 10 days, 20 days, 7 days, and 30 days, the amount of foamed scum at the aeration tank interface, the SVl of the sludge in the aeration tank, and the COD of the treated water were measured in the same manner as in Example 5. The results are shown in Table 2.

(Left below) From Table 2 and microscopic observation of activated sludge in the aeration tank,
It is clear that:

(2) When the present invention is used, the amount of additive is small compared to Comparative Example 3, and 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 3, the foamed scum at the aeration tank interface was temporarily reduced by adding the antifoaming agent, but when the addition was stopped, the foamed scum accumulated at the aeration tank interface again.

(2) In the case of the present invention, in the sludge present in the aeration tank and sedimentation tank, actinomycetes freeze at the ends of the stalks and the activated sludge forms firm flocs compared to Comparative Example 3.

(2) When using the present invention, actinomycetes are destroyed and exist in the treated water and flow out, but the COD value of the treated water is 20 m
g / / or less, which is good as treated water.

Claims (4)

[Claims] (1) Type 021N, Type 1701, Type 170
2, Type 0041, and MicrothrixPar
An agent for preventing the bulking phenomenon of activated sludge caused by at least one type of filamentous bacteria of the group Vicella (Microthrix, Parvicella), or the abnormal phenomenon of activated sludge caused by actinomycetes, the agent comprising a monoalkylamine and an epihalohydrin, or a monoalkylamine. An agent for preventing abnormal phenomena in activated sludge, comprising a water-soluble polymer obtained by reacting a mixture of dialkylamine and epihalosidrin. (2) The intrinsic viscosity [η] of the above water-soluble polymer is 0.4 dl
2. The activated sludge abnormal phenomenon prevention agent according to claim 1, wherein the activated sludge abnormal phenomenon prevention agent is less than /g. (3) Type 021N, Type 1701, Type 170
2, Type 0041, and MicrothrixPar
activated sludge or activated sludge-containing wastewater containing at least one filamentous bacterium of the group Microthrix, Parvicella, or actinomycetes; 1. A method for preventing abnormal phenomena in activated sludge, which comprises adding 0.05 to 25 parts by weight of a water-soluble polymer obtained by a reaction with 0.05 to 25 parts by weight per 100 parts by weight of dry solid content of the activated sludge. (4) The intrinsic viscosity [η] of the above water-soluble polymer is 0.4 dl
4. The method for preventing abnormal phenomena in activated sludge according to claim 3, wherein the activated sludge has a concentration of /g or less.