JPS63218297A - Process for preventing activated sludge from occurrence of abnormal phenomenon - Google Patents

Abstract

PURPOSE:To liberate actinomyces, which is a cause of bulking from activated sludge, by adding a water-soluble cationic polymer prepd. by the reaction of dialkylamine and occasionally ammonia with epihalohydrin to waste water contg. activated sludge. CONSTITUTION:0.05-25pts.wt. (basing on 100pts.wt. dry solid in activate sludge) of a water-soluble cationic polymer prepd. by the reaction of dialkylamine and occasionally ammonia (<= equimolar amt. to dialkylamine) with epihalohydrin is added to activated sludge or waste water contg. said sludge. By this method, actinomyces causing foam generation, scum generation and bulking in the waste water after precipitating activated sludge is liberated from the activated sludge. As the result, generation of foam and scum and occurrence of bulking in the activated sludge in an aeration tank or in the treated water after precipitating the activated sludge, caused by the actinomyces, is prevented specifically. Moreover, the increase of SVI (sludge volume index) of activated sludge is retarded in a short time.

Description

[Detailed Description of the Invention] [Background of the Invention] Technical Field The present invention relates to abnormal phenomena in activated sludge, such as the formation of a foam layer on the top of an aeration tank or settling tank during aeration treatment of activated sludge,
The present invention relates to a method for preventing scum formation, bulking, foaming of treated water after activated sludge sedimentation, and scum formation. More specifically, the present invention relates to a method for effectively preventing abnormal phenomena in activated sludge caused by specific actinobacteria, in a method for preventing abnormal phenomena in activated sludge by adding chemicals.

Activated sludge method is one of the biological methods used for wastewater treatment. This method utilizes the properties of activated sludge, a sludge produced by blowing air into wastewater containing organic matter and propagating microorganisms.
Activated sludge produces highly adsorbent flocs whose specific gravity is higher than that of water (for example, it is said to be around 1.003), which settles when left to stand, leaving behind clear treated water. This method takes advantage of the phenomenon of . The settled activated sludge is reused as return sludge.

Sewage, manure and various organic industrial wastewaters are commonly treated by activated sludge methods. It is known that during treatment by this method, fluctuations in the flow rate of inflowing wastewater and fluctuations in organic matter in the inflowing wastewater occur, and the microbial flora in activated sludge changes in response to these fluctuations. For example, if the free solid content in the influent raw water is low and the sludge retention time (SRT) is high, Nocardia amarae (Nocardia
aaa + arae) proliferate in large quantities in activated sludge to produce surface-active mycolic acids, promote the stabilization of air bubbles, and accumulate air bubbles containing sludge in the upper part of the aeration tank and final settling tank.
It is released into the river. The effluent itself may also foam and spoil its appearance. When this change in the microbial flora is rapid, the sludge swells, sedimentation becomes poor, the sludge rises to near the water surface, the amount of sludge overflow increases, and the treatment capacity decreases and in some cases, it becomes impossible to treat, so-called bulking. A phenomenon occurs. When this phenomenon occurs, the sludge becomes whitish and has air bubbles attached to it, and a foam layer with sludge attached to it sometimes accumulates at the top of the aeration tank, reaching a length of several tens of centimeters or more. Sludge attached to the air bubbles accumulated in the upper part of the aeration tank and sludge in the air bubbles that overflowed from the aeration tank rot and emit a bad odor, and sludge in the air bubbles accumulated in the aeration tank is mixed with treated water from the final settling tank. If the treated water is discharged, it may cause a poor appearance due to foaming of the treated water, and an increase in BOD and COD, causing environmental pollution.

As an indicator of whether activated sludge is functioning normally, SVI (Sludge Volume I)
ndex, sludge index) value. This SVI value is 1
It is expressed as the volume occupied by g of activated sludge in 30 minutes of settling. The SVI value of activated sludge that functions normally is 5.
It is 0 to 150, especially 100 or less, but that of activated sludge that has caused bulking can be as high as 300 to 800. However, the increase in SVI value caused by actinomycetes is about 200 to 300, and as a result, sewage outflow due to the rise of the sludge interface may be observed in winter.

It is difficult to restore the functions of activated sludge that has generated foaming, scum, or bulking.
In the worst case scenario, the sludge will need to be replaced, and in the case of replacement, factories will have to stop using it until the sludge has acclimated, which will have a serious impact on the factory's production plan.

In the case of public sewage systems, this can similarly become a social problem.

Prior art methods for preventing bulking of activated sludge are disclosed in Japanese Patent Publications 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 an h° 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 proliferation of filamentous documents, and is not effective when there are other causes. In addition, when using this method, even if the degree of activated sludge damage is relatively minor, it takes more than 4 days, and in some cases more than 10 sludges, before the effect is realized, and a large amount is required every day. The disadvantage is that it must be added continuously.

The method described in Japanese Patent Publication No. 58-14275 contains valine, leucine, isoleucine, glutamic acid,
A composition containing one or more amino acids such as phenylalanine and tyrosine as an active ingredient is added to activated sludge. When using this method, it is necessary to continuously add the composition containing these active ingredients to the inflowing wastewater at a rate of about 0.5 to 3 kg/yr for 3 hours or more, until the effect is exerted. has the disadvantage that it requires more than 24 hours.

The bulking phenomenon of activated sludge is caused by 5phaerot i
I us (Sphaerochilus sp.), Th1oLhrlx
(Thiotrix sp.), Aspergillus
(Aspergillus spp.), Pen1cllliui
In addition to abnormal growth of filamentous fungi such as (Penicillium spp.), a highly viscous jelly-like substance is generated in activated LRI mud depending on the season or nutritional status, which makes it difficult for the sludge to settle and causes the bulking phenomenon. It may also be shown. In the latter case, Z n C12 or
It is said that it is effective to add a cationic polyacrylamide polymer flocculant. However, according to the inventor's experiments, this method shows that activated sludge tends to contain air bubbles in an aeration tank, etc.;
It was found that the ability to treat wastewater was extremely reduced and there was no significant effect on +L when bulking occurred. In addition, to prevent foaming, scum, and bulking caused by actiobacteria, 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 the inventor's experiments, this method of mixing and spraying antifoaming agent does not suppress foaming;
It was found that this method only destroyed the bubble layer that had formed, and had little effect.

Possible Solution The present inventors have already made a proposal to solve the problems observed in the conventional bulking prevention method by adding drugs (Japanese Patent Application Laid-Open No. 61-204092 and Application No. 60-295890). These proposals are based on bulking prevention 11. The main feature is that a water-soluble cationic polymer obtained by the reaction of dialkylamine and epihalohydrin, or a water-soluble cationic polymer obtained by the reaction of dialkylamine, ammonia and epichlorohydrin, is used as the drug for use. That is.

Where the problem lies At general final treatment plants for urban sewage, bulking is most commonly caused by filamentous bacteria, and conventionally bulking has been caused by filamentous bacteria, such as Sphaerochilus (natans) and Beggiatoa (Bcg).
giatoa) are said to be representative of the causative microorganisms (Journal of Sewage Heat Treatment Society, Vol. 22, No. 252, No. 2-
12 pages (1978)).

By the way, with the recent development of sewerage systems, rainwater and domestic wastewater have come to be separated and treated. the result,
It is assumed that changes have occurred in the filamentous bacteria that cause bulking when municipal sewage, which is domestic wastewater, is treated using the activated sludge method.

[Summary of the invention]

Summary The present invention aims to specifically prevent specific abnormalities in activated sludge in response to recent changes in urban sewage. The aim is to achieve this goal by using it as a drug.

That is, the method for preventing abnormalities in activated sludge according to the present invention is to add 0.05 to 25 parts by weight per 100 parts by weight of dry solids of activated sludge to activated sludge or waste water containing it in the treatment of waste water by the activated sludge method. By adding parts by weight of a water-soluble cationic polymer obtained by the reaction of a dialkylamine, optionally ammonia (equal mole or less to the dialkylamine), and epihalohydrin, foaming and scum can be added to the treated water after activated sludge sedimentation. The method is characterized by liberating actinomycetes that should cause bulking from activated sludge.

Effects According to the present invention, the above object is achieved, and the foaming or scum formation and bulking phenomenon of activated sludge in the aeration tank and treated water after settling due to actinomycetes is specifically prevented.

That is, according to the polymer according to the present invention, when the foaming phenomenon appears in the aeration tank and signs of the foaming becoming scum and starting to accumulate, or when the bulking phenomenon is observed, when this polymer is added, The SVI value can be quickly maintained at or below the original level without substantial further expansion of the foam layer. Moreover, the drug of the present invention has a long duration of effect due to the addition of 11=H.

Therefore, if the present invention is implemented, activated sludge process control will be extremely beneficial.

In addition to the above-described effects, the present invention also provides the following effects derived from the prior invention of the present inventors.

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

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

(3) When the method of the present invention is used, the sedimentation and separation of activated sludge becomes extremely easy even in a sedimentation tank. Moreover, since the volume of sedimented material (sedimentation volume) can be significantly reduced, surplus activated sludge is less likely to be produced, and there is no need to frequently remove and incinerate surplus activated sludge.

[Detailed description of the invention]

As mentioned above, the present invention relates to a method for specifically preventing certain abnormalities in activated sludge.

Target Activated Sludge The activated sludge targeted by the present invention is one that causes foaming or scum formation in treated water after settling due to actinomycetes.

Actinomycetes that exist in activated sludge and have such negative effects include Nocardia amarae (Nocardia amarae).
amarac) series, Rhodococcus rhodochrous (R
hodococcus rhodochrous) series, and others.

If it is necessary to release such actinomycetes, they can be easily obtained from the foam tank, scum, and sludge accumulated in the upper part of the aeration tank of activated sludge of sewage.

Water-soluble cationic polymer The drug used in the present invention is a water-soluble cation whose chemical substance is obtained by the reaction of a dialkylamine and epihalohydrin, or a dialkylamine and an equimolar amount or less of ammonia and epihalohydrin. Polymer.

Although the chemical structure of this polymer is not necessarily clear, it is assumed that the nitrogen atom of the dialkylamine is quaternized and the halogen ion derived from epihalohydrin serves as its counter ion (however, the present invention (We are not in any way limited by such estimates.)

In addition, in the present invention, the "water-soluble cationic polymer obtained by the reaction of a dialkylamine, optionally ammonia (equal mole or less as the dialkylamine), and epihalohydrin" refers to the "-2 counter ion (halogen)". shall include the corresponding hydroxides in place of the anions of .

Therefore, the possible predicted structure of this water-soluble cationic polymer when it does not contain ammonia is as follows.

■ R20H Here, R1-R2 is an alkyl group derived from a dialkylamine, X"" is a halogen or other anion derived from epihalohydrin or OH"-, and n is a polymer (2 or more, preferably 3 or more). The dialkylamine from which such a polymer is to be produced is preferably one in which the number of carbon atoms in the alkyl group is about 1 to 8, particularly about 1 to 2. Specific examples of such dialkylamines include dimethylamine, diethylamine, dipropylamine, methylethylamine, methylpropylamine, ethylpropylamine, methylbutylamine, ethylbutylamine, dibutylamine, 2-ethylhexylamine, etc. It will be done.

When ammonia is used in combination, it is only necessary to add a very small amount to the dialkylamine. The amount can be selected in the molar ratio of ammonia/dialkylamine (1) in the range of 0.0001 to 1.0, with a particularly preferred molar ratio of 0.0001 to 1.0.
It is in the range of 001 to 0.1.

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

To react dialkylamine, ammonia (when used), and epihalohydrin, the number of moles of dialkylamine and ammonia is approximately equal to the number of moles of epihalohydrin, a closed reaction vessel equipped with a stirrer is used, and an inert Under a gas atmosphere, the internal temperature of the reaction vessel is set to 30-11
The temperature range is preferably 0°C.

More specifically, a 20-70% strength by weight aqueous solution of dialkylamine or dialkylamine and optionally ammonia,
Pour into a closed reaction container equipped with a stirrer, reflux condenser, thermometer, etc., replace the atmosphere inside the container with nitrogen gas, and while stirring,
It is preferable to add epino)lohydrin continuously or batchwise while controlling the temperature inside the reaction vessel to prevent it from rising too much. When adding ammonia, it is preferable to first add epihalohydrin to the dimethylamine aqueous solution and then add ammonia. After adding Epi-710 hydrin and dialkylamine (and ammonia) to the reaction vessel, add an alkali metal or alkaline earth metal oxide or hydroxide to the reaction vessel at a rate of 0.00001 per mole of epichlorohydrin. ~0.01 mol added, 30~6
When kept in the temperature range of 0° C. for several hours, the molecular weight of the resulting polymer may increase. Note that when this reaction product is maintained as an aqueous solution at a temperature of about 30° C. under a nitrogen gas atmosphere, a reaction in which the molecular weight increases slowly proceeds for about two months. During this time, if air or oxygen is introduced into the container, the reaction that increases the molecular weight will not proceed.

The polymer thus obtained can be further processed to replace the halogen (derived from epihalohydrin) as a counterion with another anion or to remove the counterion and convert this cationic polymer into a hydroxide. It is clear from the above that it is also possible to do this.

- The polymer obtained as described above has an intrinsic viscosity [
η], it is possible to judge the size of the molecule;
In the method of the present invention, [η] is 0°001 dl/g or more, more preferably 0.01 dl/g or more. [If η is too small, the adsorption to activated sludge will decrease and the sustainability of the bulking prevention effect will decrease, which is not preferable.

The water-soluble cationic polymer thus obtained can also be converted into a solid by removing the solvent (usually water). However, it is preferable to use the solution produced as an aqueous solution as it is or after diluting or concentrating as necessary to prevent bulking of activated sludge.
It is also normal.

Prevention of abnormal phenomena in activated sludge Except for the target activated sludge to be prevented from abnormal phenomena as described above and the changes in treatment conditions that should occur as a result, bulking of activated sludge by the addition of chemicals according to the present invention The prevention method is essentially the same as the conventional one.

Specifically, a water-soluble cationic polymer is prepared as an aqueous solution at an appropriate concentration, for example, about 0.1 to 10 ffl%, and this aqueous solution is prepared by one of the following methods or a combination of two or more of these methods. It can be added according to the following.

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

(2) Method of adding directly to an aeration tank or settling tank where bulking of activated sludge is occurring.

(3) Method of adding to returned sludge.

If the amount of the water-soluble cationic polymer used is too small, the object of the invention will not be achieved, which is not preferable, and if it is too large, it will be washed out of the system together with wastewater, which is not preferable. The amount used is preferably selected within the range of 0.05 to 25 parts by weight based on 100 parts by weight of dry solid content of the activated sludge. More preferably, it is in the range of 0.1 to 10 parts by weight.

When a water-soluble cationic polymer is added to activated sludge in the above range, no increase in SVI and no sludge outflow due to foaming or scum generation will be observed for one month or more. When signs of accumulation of a foamed layer containing sludge in the upper part of the aeration tank are observed, at that point it is preferable to add the water-soluble cationic polymer in the above range.

Experimental Examples Example 1 The monthly average wastewater treatment amount is 3500 m/mouth, and the BOD of the raw water flowing into the aeration tank after removing the suspended solids (SS) that tend to settle in the settling tank is 220 ppm, n. - Hexane soluble content is 30 ppm and suspended solid content is 120 ppm.
pm, and its 88th component is organic matter 60%.
There are public sewage treatment plants that treat raw water that is more than %. The time-varying changes in inflow raw water over the course of a day are extremely large.
Most of the wastewater comes from sewage from an apartment complex, where the amount of water to be processed is about six times the lowest at 9 a.m. and 10 p.m., and from several fish processing plants. This is a public sewage treatment plant that uses activated sludge to treat the separated urban sewerage wastewater that occupies the majority of the area, using a 10,001rt aeration tank and a 500m final settling tank. The settled sludge volume index (SVI value) of the aeration tank is about 200, but a unique cycle occurs, and there is about 10 cm of sediment at the top of the aeration tank.
The foam layer, which had become brownish-brown by entrapping sludge for about 20 (7) hours, remained forever, but this foam layer overflowed from the top of the aeration tank and polluted the area, and the overflowing It rots and becomes a source of bad odor, and to make matters worse, the foam layer containing sludge flows into the final settling tank and flows out with the treated water, resulting in BOD and COD values of the effluent exceeding 20 ppm each. . The operating conditions at this treatment plant are that the return rate of 1q mud to be treated is 50%, the air ratio to the raw water is 10 times, and a diffuser plate is used to introduce air. The average age of the sludge was 18 days, and the dry sludge concentration (MLSS) of the returned sludge was 4500 pi) m%. The MLSS in the aeration tank was operating at 2100 ppm.

When the sludge in the aeration tank and settling tank at this treatment plant was stained with Durham and observed using a phase contrast microscope, it was found that filamentous bacteria of typical actinomycetes attached to floc-forming bacteria were found in and around the sludge. observed a lot.

The sludge contained actinomycetes, and the sludge adhered to mycolic acid secreted by actinomycetes and their filamentous forms, reducing the density of the sludge and making it difficult to settle.

Furthermore, dissolved oxygen is consumed rapidly, and a large amount of air, about 10 times the air magnification, must be introduced into the aeration tank. Also,
Because a large amount of air is introduced, the aeration tank is vigorously agitated, and the shearing force causes the sludge to be crushed into fine particles, resulting in a small amount of fine sludge flowing out, resulting in an average SS value of 15 pp.
It showed a relatively high value of m.

At this treatment plant, until the molar ratio of epichloro-1-hydrin and 50% dimethylamine aqueous solution becomes 1:1.05,
The mixed reaction composition obtained by adding epichlorohydrin to a 50% dimethylamine aqueous solution while maintaining the reaction temperature at 90°C and mixing with stirring (intrinsic viscosity [η] measured with a 2 mol/liter KBr aqueous solution) 0.02 dl/g composition) was continuously added at a rate of 80 g/min to the return sludge line while diluting it 100 times with tap water for 50 hours, and at the same time, it was added to the foaming tank retained in the upper part of the aeration tank. As shower water continued to be applied, the brown foam layer that had accumulated at the top of the aeration tank gradually decreased from the third hour onward. After 9 hours, many filamentous bacteria such as actinomycetes were observed in the treated water from the final settling tank, and the actinomycetes in the aeration tank were detached from the sludge, increasing the density of flocs.

The SVI value decreased to 150, and the position of the sludge interface in the final settling tank also decreased. After 50 hours, the SVI value reached 100. It was confirmed that filamentous bacteria such as actinomycetes were extremely reduced in the sludge present in the aeration tank at this time. Furthermore, the activated sludge formed firmer flocs than before addition. As a result, after 100 hours, the brown foam layer that had accumulated at the top of the aeration tank had largely disappeared, and the sedimentation properties had been significantly improved, with the SVI value reaching 90. MLSS value 5500pp
m, and the sludge concentration in the aeration tank also reached an MLSS value of 2300p.
As the pm has increased, good quality treated water can be obtained with normal operation of raw water, and therefore, even if the inflow of raw water is large in the morning and evening, the concentration of returned sludge will be high. Therefore, the sludge concentration in the aeration tank can be changed simply by temporarily adjusting the return rate, and the sludge interface in the settling tank does not rise and flow out.

Filamentous bacteria such as actinomycetes are destroyed and flow out, but the suspended solids concentration at this time is less than 5 ppm, and the BOD and COD values of the effluent after chlorine sterilization are 20% each.
It was less than ppm, and was in good condition as effluent water.

Example 2 In the treatment plant of Example 1, filamentous bacteria such as actinomycetes were generated in abundance, producing a unique odor, and approximately 1.
A foam layer that had become brownish-brown by trapping sludge for about 20 cm from 0c+n remained forever, but this foam layer overflowed from the top of the aeration tank, polluting the surrounding area, and the overflowing material rotted. To make matters worse, the foam layer containing sludge flowed into the final settling tank and flowed out together with the treated water, causing the BOD and COD values of the effluent to exceed 20 ppm each. In addition, the SVI value exceeded 250. The operating conditions were the same as in Example 1. When the sludge in the aeration tank and settling tank at this treatment plant was stained with Durham and observed using a phase contrast microscope, it was found that in and around the sludge, typical actinomycete filamentous bacteria attached to floc-forming bacteria were observed. were often observed. The sludge contains actinomycetes,
The sludge adhered to mycolic acids secreted by the sludge and actinomycetes that had changed their filamentous form, reducing the density of the sludge and making it difficult to settle. When the sludge in the aeration tank and settling tank at this treatment plant was Durham stained and observed using a phase contrast microscope, it was found that there were many filamentous bacteria of typical actinomycetes attached to floc-forming bacteria in and around the sludge. observed.

At this treatment plant, epichlorohydrin was added to a 50% dimethylamine aqueous solution while maintaining the reaction temperature at 85°C until the molar ratio of epichlorohydrin and 50% dimethylamine aqueous solution was 1:1, and the mixture was stirred. The mixed reaction composition obtained by
was continuously added to the return sludge line for 60 hours at a rate of 75 g/min while diluting it 100 times with tap water, and at the same time continued to spray shower water on the foam layer staying at the top of the aeration tank. From the hour onwards, the brown foam layer that had accumulated at the top of the aeration tank gradually decreased. After 15 hours, the brown foam layer that had remained at the top of the aeration tank had decreased by about 30%, and in addition, many filamentous bacteria such as actinomycetes were observed in the treated water from the final settling tank. The actinomycetes in the aeration tank were detached from the sludge, and the density of the flocs increased. The SVI value decreased to 150, and the position of the sludge interface in the final settling tank also decreased.

After 50 hours, the SVI value reached 100. It was confirmed that filamentous bacteria such as actinomycetes were extremely reduced in the sludge present in the aeration tank at this time.

Furthermore, the activated sludge formed firmer flocs than before addition. After 200 hours, the brown foam layer that had remained in the upper part of the aeration tank had mostly disappeared, and after flowing into the settling tank, it no longer flowed out as effluent water. In addition, the sedimentation property was significantly improved and the SVI value became 90, and the returned mud concentration increased to MLSS.
The value rose to 6,500 ppm, and the sludge concentration in the aeration tank also reached MLS.
Since the S value has increased to 2,400 ppm, it has become possible to obtain good quality treated water with normal operation. Furthermore, when the air magnification was 8 times, the dissolved oxygen concentration at the outlet of the aeration tank exceeded 1.5 ppm. Furthermore, even if the inflow of raw water varies greatly between morning and evening, the concentration of returned sludge is high, so simply by temporarily adjusting the return rate, the sludge concentration in the aeration tank can be changed, and the sedimentation Sludge no longer flows out of the tank due to poor separation. Furthermore, since the concentration of returned sludge has increased, the sludge is condensed in the gravity-type thickening tank, and thick sludge can be sent to the digestion tank, which increases the rate of generation of digestion gas and increases the efficiency of the digestion layer. did. In addition, when dewatering digested sludge, cationic polyacrylamide is used as a flocculant to dry the sludge! lf′! 0 for quantity
．． Previously, dehydration was performed using a centrifugal decanter using 6% by weight, but now dehydration can be performed using 0.5 iflr (volume%) of flocculant.

Filamentous bacteria such as actinomycetes are destroyed and flow out, but the suspended solids concentration at this time is less than 5 ppm, and the BOD and COD values of the effluent after chlorine sterilization are 20% each.
It was less than ppm, and was in good condition as effluent water.

After adding the water-soluble cationic polymer, a rapid increase was suppressed for approximately one month, despite the fact that sewage wastewater was thought to contain actinomycetes and other filamentous bacteria. .

Example 3 In the treatment plant of Example 1, a large amount of filamentous bacteria such as actinomycetes was generated, producing a unique odor, and the upper part of the aeration tank was filled with about 1
The foam layer, which had become brownish-brown by entrapping sludge from 0 cm to 20 G, remained forever, but this foam layer overflowed from the top of the aeration tank, polluting the surrounding area, and the overflowing material rotted. This can become a source of bad odors, and even worse,
The foamed layer containing sludge entered the final settling tank and flowed out together with the treated water, resulting in BOD and COD values of the effluent exceeding 20 ppm, respectively. In addition, the SVI value exceeded 250. The operating conditions were the same as in Example 1. When the sludge in the aeration tank and settling tank at this treatment plant was stained with Durham and observed using a phase contrast microscope, it was found that there were
Many typical filamentous actinomycete bacteria attached to floc-forming bacteria were observed. The sludge contains actinomycetes, and the sludge adheres to the mycolic acid secreted by the actinomycetes and to filamentous forms of the actinomycetes themselves, reducing the density of the sludge and making it difficult to settle. was. When the sludge in the aeration tank and settling tank at this treatment plant was Durham stained and observed using a phase contrast microscope, it was found that there were many filamentous bacteria of typical actinomycetes attached to floc-forming bacteria in and around the sludge. observed.

In this treatment plant, the molar ratio of epichlorohydrin, 50% dimethylamine aqueous solution, and 12% ammonia aqueous solution is 1:
Add epichlorohydrin to the mixed amine of 50% dimethylamine aqueous solution and 12% ammonia water while maintaining the reaction temperature at 90°C until the ratio is 1.05:0.1.
The mixed reaction composition obtained by stirring and mixing was further stirred and mixed for 10 hours.The reaction composition obtained by further stirring and mixing for 10 hours had an intrinsic viscosity [η] of 0. 0
2 dl/g composition) at a rate of 70 g/min.
When the sludge was continuously added to the return sludge line for 65 hours while being diluted with tap water to 0.0 times, and at the same time shower water was continued to be applied to the foam layer that had accumulated at the top of the aeration tank, the sludge remained at the top of the aeration tank from the mouth for 5 hours. The brown foam layer that had been present gradually decreased. Nine hours after the addition started, the brown foam layer that had accumulated at the top of the aeration tank had decreased by about 30%, and historically there were many filamentous bacteria such as actinomycetes in the treated water from the final settling tank. At the same time, the actinomycetes in the aeration tank were detached from the sludge, and the density of flocs increased. 5
The VI (fi) decreased to 160, and the position of the sludge interface in the final settling tank also decreased. After 50 minutes, the SvI value decreased to 110.
Became. It was confirmed that filamentous bacteria such as actinomycetes (Nocardia) were extremely reduced in the sludge present in the aeration tank at this time. In addition, compared to before addition, activated sludge
It has formed a solid flock. After 150 hours, the brown foam layer that had remained in the upper part of the aeration tank had mostly disappeared, and after flowing into the settling tank, it no longer flowed out as effluent water.

In addition, the sedimentation property has been significantly improved and the SVI value has become 95, and the returned sludge concentration has increased to an MLSS value of 6500pp.
m, and the sludge concentration in the aeration tank also reached an MLSS value of 2400p.
Since we were able to achieve Wl as well as pm, we were able to process raw water and obtain good quality treated water during normal operation. In addition, the air magnification is 8 times, and the dissolved oxygen concentration in the aeration tank is 2.0.
ppm. Furthermore, even if the inflow of raw water varies greatly between morning and evening, the concentration of returned sludge is high, so simply by temporarily adjusting the return rate, the sludge concentration in the aeration tank can be changed, and the sedimentation Sludge no longer flows out of the tank due to poor separation. Furthermore, because the concentration of returned sludge has increased, the sludge is thickened in a gravity-type thickening tank, making it possible to send thick sludge to the digestion tank, increasing the rate of generation of digestion gas and increasing the efficiency of the digestion layer. .

Filamentous bacteria such as actinomycetes are destroyed and flow out, but the suspended solids concentration at this time is less than 5 ppm, and the BOD and COD values of the effluent after chlorine sterilization are 20% each.
It was less than ppm, and was in good condition as effluent water.

Example 4 In the treatment plant of Example 1, a large amount of filamentous bacteria such as actinomycetes was generated, producing a unique odor, and about 10
The foam layer, which had become brownish-brown by trapping sludge for about 20 cm to 20 cm, remained forever, but this foam layer overflowed from the top of the aeration tank, polluting the surrounding area, and the overflowing material rotted. This can become a source of bad odors, and even worse,
The foamed layer containing sludge entered the final settling tank and flowed out together with the treated water, resulting in BOD and COD values of the effluent exceeding 20 ppm, respectively. In addition, the SVI value exceeded 220. The operating conditions were the same as in Example 1. When the sludge in the aeration tank and settling tank of this treatment plant was Durham stained and observed using a phase contrast microscope, it was found that there were many filamentous bacteria of typical actinomycetes attached to floc-forming bacteria in and around the sludge. observed. The sludge contains actinomycetes, and the sludge adheres to the mycolic acid secreted by them and to actinomycetes (Nocardia) that have changed their filamentous form.
The density of the sludge was reduced to make it difficult to settle. When the sludge in the aeration tank and settling tank at this treatment plant was Durham stained and observed using a phase contrast microscope, it was found that there were many filamentous bacteria of typical actinomycetes attached to floc-forming bacteria in and around the sludge. observed.

In this treatment plant, the molar ratio of epichlorohydrin, 50% dimethylamine aqueous solution, and 12% ammonia aqueous solution is 1:
Add epichlorohydrin to a 50% dimethylamine aqueous solution while maintaining the reaction temperature at 90°C until the ratio of 1:Oll is reached, and add it to the mixed reaction composition obtained by stirring and mixing. A reaction composition obtained by adding 12% ammonia water and mixing with the mixture after 10 hours (a composition with an intrinsic viscosity [η] of 0.12 dl/g measured with a 2 mol/liter KBr aqueous solution) was prepared. This was diluted 100 times with tap water at a rate of 70g/min and sent to the return sludge line.
At the same time as continuous addition for 0 hours, shower water was continued to be applied to the foam layer staying at the top of the aeration tank, and from the 5th hour onwards, the brown foam layer staying at the top of the aeration tank gradually decreased. . After 9 hours, the brown foam layer that had accumulated in the negative part of the aeration tank had decreased by about 30%, and
Many filamentous bacteria such as actinomycetes were observed in the treated water from the final settling tank, and actinomycetes (Nocardia) in the aeration tank were detached from the sludge, increasing the density of flocs. The SVI value decreased to 160, and the position of the sludge interface in the final settling tank also decreased. After 50 hours, the SVI value will be 1.
It became 10. It was confirmed that filamentous bacteria such as actinomycetes were extremely reduced in the sludge present in the aeration tank at this time. Furthermore, the activated sludge formed firmer flocs than before addition. After 150 hours, the brown foam layer that had remained in the upper part of the aeration tank had mostly disappeared, and after flowing into the settling tank, it no longer flowed out as effluent water. In addition, the sedimentation properties were significantly improved and the SV
The I value becomes 85, and the returned sludge concentration increases to MLS.
The S value has increased to 6,500 ppm, and the sludge concentration in the aeration tank has also increased to the MLSS value of 2,400 ppm.
Raw water treatment has become possible to obtain good quality treated water with normal operation. Furthermore, when the air magnification was 8 times, the dissolved oxygen concentration at the outlet of the aeration tank exceeded 1.5 ppm. Furthermore, even if the inflow of raw water varies greatly between morning and evening, the concentration of returned sludge is high, so simply by temporarily adjusting the return rate, the sludge concentration in the aeration tank can be changed, and the sedimentation Sludge no longer flows out of the tank due to poor separation. Furthermore, since the concentration of returned sludge has increased, the T9 mud is concentrated in the gravity thickening tank, allowing thick sludge to be sent to the digestion tank, increasing the rate of generation of digestion gas and increasing the efficiency of the digestion layer. did. In addition, when dewatering digested sludge, cationic polyacrylamide is used as a flocculant, and 0.00% of the dry weight of the sludge is used. I used 6% by weight and dehydrated with a centrifugal decanter, but the amount of flocculant used was 0.5ffi! I was able to dehydrate with 9.6.

Filamentous bacteria such as actinomycetes are destroyed and flow out, but the suspended solids concentration at this time is less than 5 ppm, and the BOD and COD values of the effluent after chlorine sterilization are 20% each.
It was less than ppm, and was in good condition as effluent water.

After the addition of the water-soluble cationic polymer, a rapid increase was suppressed for about one month, even though filamentous bacteria such as actinomycetes were thought to be contained in the sewage wastewater.

Comparative Example 1 In the treatment plant of Example 1, a large amount of filamentous bacteria such as actinomycetes was generated, producing a unique odor, and about 10
The foam layer that had become brownish-brown by enveloping sludge for about 20 cm from 0111 did not disappear forever.
The overflow will rot and become a source of bad odors, and to make matters worse, the foam layer containing sludge will flow into the final settling tank and flow out with the treated water, reducing the BOD and COD values of the effluent. Each exceeded 20 ppm. Also, the SVI value is 22
Exceeded 0. The operating conditions were the same as in Example 1. When the sludge in the aeration tank and settling tank of this treatment plant was Durham stained and observed using a phase contrast microscope, it was found that in and around the sludge there were typical actinomycete filamentous bacteria attached to floc-forming bacteria. observed a lot. The sludge contained actinomycetes, and the sludge adhered to the mycolic acid secreted by the actinomycetes and to filamentous forms of the actinomycetes themselves, reducing the density of the sludge and making it difficult to settle. . Aeration tank of this treatment plant = l! Second, when the sludge in the settling tank was stained with Durham staining and observed under a phase contrast microscope, many filamentous bacteria of typical actinomycetes attached to floc-forming bacteria were observed in and around the sludge.

Therefore, an antifoaming agent was dissolved and added to the shower water from the top of the aeration tank. The antifoaming agent is a special paraffin ester compound (Daito Pharmaceutical Co., Ltd.'s "Minecon Cl") mixed with water.
It was diluted to % by weight and added continuously for 30 days at a rate of 100 liters/minute from the shower water line at the top of the aeration tank.

An antifoaming effect was observed in areas exposed to shower water, but a large amount of antifoaming agent was required to obtain a sufficient effect.

However, with the use of antifoaming agents, it has been fundamentally impossible to release actinomycetes in sludge from activated sludge.

Note that the foaming phenomenon of the effluent water could be suppressed by adding an antifoaming agent to the effluent water.

Claims (1)

[Claims] In the treatment of wastewater by the activated sludge method, activated sludge or wastewater containing the same is added with 0.05 to 25 parts by weight of dialkylamine and optionally ammonia (dialkylamine and By adding a water-soluble cationic polymer obtained by reacting (equal mole or less) with epihalohydrin, actinomycetes that should cause foaming, scum, or bulking in treated water after activated sludge sedimentation are liberated from activated sludge. A method for preventing abnormal phenomena in activated sludge, which is characterized by: