JPH06233994A - Bulking preventive agent for activated sludge and method therefor - Google Patents

Abstract

PURPOSE:To make it possible to prevent bulking from occurring without affecting useful activated sludge adversely. CONSTITUTION:This bulking preventive agent for activated sludge consists of at least, one kind of 2-bromo-2-nitropropane-1,3-diol and it s lower aliphatic esters, or at least, one king of 2-bromo-2-nitro-propanel-1,3-diol and its lower aliphatic ester and/or a hydrogen peroxide supplying compound and/or a cationic polymer coagulant as effective components.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to bulking caused by filamentous microorganisms frequently occurring in the treatment of wastewater containing organic substances by the activated sludge method, and more particularly to a bulking inhibitor and a method for preventing filamentous bulking.

[0002]

2. Description of the Related Art The activated sludge method has been widely adopted as a method for treating organic wastewater, but the bulking phenomenon in which sludge that has failed to settle in a settling tank flows out together with the treated water frequently occurs. It has become a drawback of the method. Among them, bulking, which is predominant in microorganisms, especially filamentous bacteria, in sludge microorganisms is one of the most difficult phenomena to solve.

The causes of bulking are deficiency of dissolved oxygen, imbalance of nutrition, contamination of toxic substances, influence of temperature, fluctuation of influent flow rate and organic matter, and various molds, filamentous fungi and actinomycetes grown in the sewer pipe. It is difficult to eliminate all of these factors all at once, because changes in microorganisms such as the above may occur, but these factors may occur in a complex combination.
As a bulking inhibitor and a method for preventing this bulking phenomenon, there have been conventionally used bactericidal agents such as chlorine agents and hydrogen peroxide, inorganic flocculants such as iron salts, aluminum salts and calcium salts, and cationic acrylamide polymer flocculants. Is proposed. Further, a bulking inhibitor containing, as an active ingredient, a halogenated ester derivative such as 1,4-bis (bromoacetoxy) butene-2 known as an industrial bactericide has also been proposed (see JP-A-53-64963). ).

[0004]

Ordinary bactericides such as chlorine agents and hydrogen peroxide are intended to suppress the growth of microorganisms, especially filamentous bacteria. However, the microorganisms have actively propagated. Since, the effect of addition is reduced, these must be applied in the early stages, and its sterilization,
Since the bacteriostatic spectrum is wide, the coexisting activated sludge is also adversely affected, and therefore, the amount of the chemicals added is greatly limited, which makes it impossible to sufficiently deal with bulking.

The addition of the inorganic and organic flocculants cannot damage the microorganisms, and the addition amount tends to gradually increase to prevent bulking, which is not a solution to the fundamental problem. There wasn't. Further, a halogenated ester derivative such as 1,4-bis (bromoacetoxy) butene-2 is a fungicide having selectivity for a filamentous fungus group that causes the bulking phenomenon. Day to 30
MIC against mycelial bacteria such as Spherocillus spp., Which is a major cause of bulking, though it takes days and has low toxicity.
[Minimum inhibitory concentration (target mycelial bacterium: spherotilus species
(Sphaerotilus sp.) )] Is an indicator of fish toxicity, LC50
It is similar to (experimental animal: Himedaka), and there is a problem that it is not suitable for use as wastewater discharged into a river from the viewpoint of safety.

[0006] Therefore, there is a demand for a chemical agent which is safe to discharge wastewater into a river and has no effect on coexisting excellent activated sludge and which is selectively effective against microorganisms which are the main cause of bulking. There is. In order to solve the above problems, the inventors of the present invention have conducted extensive studies and found that 2-bromo-2-nitropropane-1,3-diol and its lower fatty acid ester against mycelial bacteria such as S. faecalis species. 1 / of that LC50
Inhibiting its development at concentrations below 20 and 2-bromo-2
-Nitropropane-1,3-diol in combination with hydrogen peroxide-supplying compound and the addition of cationic polymer flocculant have a remarkable synergistic effect. 2-Bromo-2-nitropropane-
It was found that 1,3-diol and its lower fatty acid ester have no effect on excellent activated sludge bacteria at the growth inhibitory concentration against mycobacterial bacteria such as Spherocillus spp. Which is the main cause of bulking. It was confirmed that the compound was effective as an inhibitor, and the present invention was completed.

[0007]

Thus, according to the present invention, at least one of 2-bromo-2-nitropropane-1,3-diol and its lower fatty acid ester is contained as an active ingredient. An effective amount of at least one of 2-bromo-2-nitropropane-1,3-diol and its lower fatty acid ester is added to a method for treating bulking inhibitor of activated sludge and wastewater containing organic matter using activated sludge. A method for preventing bulking is provided.

In the present invention, 2-bromo-2-nitropropane-1,3-diol or its lower fatty acid ester, which is an active ingredient, is disclosed in JP-B-40-8917, JP-A-56-120603,
It is known as an industrial fungicide from JP-A-56-128737 and can be synthesized according to the method described in the above-mentioned publication. Also,
2-Bromo-2-nitropropane-1,3-diol is a trade name B
Ronopol (trademark) is commercially available from The Boots Company, and this commercial product can also be used. In the present invention, the organic matter-containing wastewater means wastewater containing a BOD component, a COD component, a TOC component, and a loss on ignition.
Specifically, it means general domestic wastewater, industrial wastewater, and the like.

"Lower fatty acid" represented by 2-bromo-2-nitropropane-1,3-diol lower fatty acid ester used in the present invention means "di-lower fatty acid",
Examples of the "lower fatty acid" include formic acid, acetic acid, propionic acid and the like, and formic acid and acetic acid are particularly preferable.
The active ingredient of the present invention is usually preferably used in the form of a liquid formulation. However, the present invention is not limited to this, and it may be used in the form of powder, spray or the like.

In the case of liquid preparations, amides such as dimethylformamide, glycols such as ethylene glycol, propylene glycol, diethylene glycol and dipropylene glycol, methyl cellosolve, phenyl cellosolve, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether and triglyceride. Glycol ethers such as propylene glycol monomethyl ether, alcohols having up to 8 carbon atoms or methyl acetate, ethyl acetate, 3-methoxybutyl acetate, 2-ethoxymethyl acetate, 2-ethoxyethyl acetate, propylene carbonate, dimethyl glutarate, etc. Hydrophilic organic solvents such as esters and water are used to dissolve the active ingredient of the present invention.

When used as a powder, a direct or solid diluent (eg, kaolin, clay, bentonite, CMC, etc.)
The powder may be diluted with, or various surfactants may be used. In the present invention, the above-mentioned active ingredient is usually added to the aeration tank or the preparation tank which is a pre-process of the precipitation tank,
The amount added is usually 2 to the drainage as an active ingredient.
An amount of 20 mg / l, preferably 5-10 ml / l is sufficient to prevent bulking. Even with this upper limit of the addition amount, there is no effect on the coexisting good activated sludge at all, and therefore the bulking prevention treatment with a high safety factor for the good activated sludge becomes possible. In addition, even when the wastewater containing the upper limit of the amount added is discharged into a river, the amount is 1/2 of the LC ₅₀ ,
Usually, since it is discharged is further diluted, the LC ₅₀ 1 /
It will be 20 or less, which enables highly safe processing.

Further, according to the present invention, 2-bromo-2-
Provided is an anti-bulking agent for activated sludge, which comprises at least one of nitropropane-1,3-diol and its lower fatty acid ester and a hydrogen peroxide-supplying compound as active ingredients. In the present invention, the hydrogen peroxide supply compound is a compound that generates hydrogen peroxide in water, and examples thereof include hydrogen peroxide, percarbonates (eg sodium percarbonate, potassium percarbonate, etc.), peracetic acid and the like. Among them, hydrogen peroxide is particularly preferable in terms of economy and handling.

By using at least one or more of 2-bromo-2-nitropropane-1,3-diol and its lower fatty acid ester in combination with a hydrogen peroxide-supplying compound, the selectivity for Spherocillus species is further improved. Therefore, it is preferable. In other words, due to the synergistic effect, the effective concentration of Spherocillus species is reduced compared to the effective amount of each alone, thereby preventing the effect on excellent activated sludge and the higher safety factor against discharge to rivers. Processing becomes possible.

The blending ratio in which the synergistic effect of both drugs is exerted is preferably 5: 1 to 1: 500 as a weight ratio, and 5:
1 to 1:50 is particularly preferable. Another embodiment of the present invention is a method of treating organic matter-containing wastewater with activated sludge, comprising the step of peroxidizing 2-bromo-2-nitropropane-1,3-diol and at least one of its lower fatty esters. A method for preventing bulking is provided which comprises adding an effective amount of a hydrogen-supplying compound separately or simultaneously. Each of the active ingredients of the present invention may be used as a one-part preparation or as separate preparations, and it is generally preferable to use them as a preparation in the form of a liquid preparation. However, the present invention is not limited to this, and may be used in the form of powder or the like. In the case of a liquid preparation, both compounds are water-soluble, so they can be diluted with water to be formulated. At this time, the hydrophilic organic solvent may be further used in combination.

The addition amount of the active ingredient of the present invention is usually 2 to 25 mg / l, preferably 15 to 25 mg / l, based on the total amount of the waste water, so that bulking can be sufficiently prevented. Even with the addition of the upper limit of the addition amount, since there is no effect on the coexisting excellent sludge, it is possible to perform the bulking prevention treatment with a high safety rate for the excellent sludge.

Further, according to the present invention, there are provided a bulking preventive agent and a preventive method which further contain a cationic polymer flocculant. Bulking can be quickly eliminated by using a cationic polymer flocculant together. The cationic polymer flocculant used in combination has a molecular weight of 1,000 to 50.
Polycondensation product of 0,000 alkylene dichloride and alkylene polyamine, polyethyleneimine, polydialkylaminoalkyl (meth) acrylate, polyvinylimidazole, Mannich compound of polyacrylamide, Hofmann degradation product of polyacrylamide, amine-epihalohydrin polycondensation product, chitosan, Examples thereof include cyclized polymers of diallylammonium halides and polyacrylic acid esters. Among these cationic polymer flocculants,
It is preferable to use an amine-epichlorohydrin polycondensate having a molecular weight of 50,000 to 200,000, preferably 80,000 to 140,000 from the viewpoint of the effect of preventing bulking. These cationic polymer flocculants are usually blended in a weight ratio of 0.4 to 10 with at least one of 2-bromo-2-nitropropane-1,3-diol and its lower fatty acid ester being 1; , 2 to 250 mg / l for organic matter-containing wastewater, preferably 10 to 10
Bulking can be promptly eliminated by using together with the addition amount of 0 mg / l.

[0017]

EXAMPLES The present invention is illustrated by the following formulation examples and test examples. Formulation Example 1 2-Bromo-2-nitropropane-1,3-diol 20 parts by weight Diethylene glycol monomethyl ether 80 parts by weight Formulation Example 2 2-Bromo-2-nitro-1,3-diacetyloxypropane 20 parts by weight diethylene glycol monomethyl ether 80 parts by weight Formulation Example 3 2-bromo-2-nitro-1,3-diformyloxypropane 20 parts by weight Diethylene glycol monomethyl ether 80 parts by weight Formulation Example 4 2-bromo-2-nitropropane-1,3-diol 7.5 parts by weight Part Hydrogen peroxide aqueous solution (containing 30% hydrogen peroxide) 25 parts by weight Water 67.5 parts by weight Formulation Example 5 2-bromo-2-nitro-1,3-diacetyloxypropane 7.5 parts by weight Hydrogen peroxide aqueous solution (hydrogen peroxide 30 %) 25 parts by weight Water 67.5 parts by weight Formulation Example 6 2-Bromo-2-nitro-1,3-diformyloxypropane 7.5 parts by weight Hydrogen peroxide aqueous solution (containing 30% hydrogen peroxide ) 25 parts by weight Water 67.5 parts by weight Formulation Example 7 2-Bromo-2-nitropropane-1,3-diol 7.5 parts by weight 40% by weight aqueous solution of polycondensate of amine-epichlorohydrin (molecular weight 125,000) 20 parts by weight water 72.5 parts by weight Part Test Example 1 [2-bromo-2-nitropropane- against standard bacteria
Efficacy test based on various combinations of 1,3-diol, 2-bro-2-nitropropane-1,3-diol and hydrogen peroxide] Sphaerotil pre-cultured in CGY liquid medium with 1/10 concentration
Inoculate a fixed amount of us natans IAM 12068 bacterial solution, and then add each drug to a predetermined concentration. 8 at 26 ℃
The culture was allowed to stand for a day, and it was confirmed whether or not a mycelial bacterium coat was formed on the liquid surface of the medium. The minimum concentration of each drug (MIC 8 days) and LC ₅₀ (experimental animal: Japanese medaka) that did not show growth even after 8 days were determined. The results are shown in Table 1 and FIG.

In Table 1, LC ₅₀ / MIC is LC ₅₀ (mg /
It is the ratio obtained by dividing l) by MIC8 days (mg / l), and is an index of the safety factor when discharged into a river. The alphabets in the reagent reagent name column represent the following compounds. A: 2-bromo-2-nitropropane-1,3-diol B: hydrogen peroxide C: sodium hypochlorite D: 1,4-bis (bromoacetoxy) -2-butene E: 1-bromoacetoxy- 2-Propanol F: 2-Bromo-hydroxyacetophenone G: 1-Bromo-2-nitro-2-hydroxymethylpropanediol-1,3

[0019]

[Table 1] Test Example 2 [Efficacy Confirmation Test as Anti-bulking Agent] Glucose 720 mg / l, Starch 400 mg / l, Peptone 320 mg / l, Urea 16 mg / l, Monopotassium Phosphate 40 mg / l
Synthetic wastewater was prepared. The pH of this synthetic wastewater is 8.1, T
OC is 580 mg / l, COD is 820 mg / l, BOD is 10
The composition is 00 mg / l, nitrogen 50 mg / l, phosphorus 10 mg / l, and is a composition in which bulking easily occurs. Next, an experimental wastewater treatment device as shown in FIG. 2 (aeration tank capacity 4 liters, sedimentation separation tank capacity 1
l) is assembled and the activated sludge is cultivated using this device and the above-mentioned synthetic wastewater, and the SVI in the sedimentation tank is cultivated.
The value (volume ml / g per 1 g of sludge) was determined. As the activated sludge, the sludge of a certain sewage treatment plant was acclimated with the above-mentioned synthetic wastewater for 2 weeks by the batch method. By this method, operation was carried out under the conditions of BOD load of 0.8 g / l · day, SRT of 8 days, raw water BOP concentration of 800 mg / l, and aeration air amount of 4 l / min. The SVI value of activated sludge is 1 from the initial 50-110 ml / g.
After 0 days, it became a bulking state of 600 ml / g or more. By this test method, the efficacy confirmation test of the bulking inhibitor of the present invention was conducted.

That is, the reagent solution was added just before the aeration mixing tank so that the amount of the reagent was a predetermined amount relative to the amount of synthetic wastewater (raw water), and the SVI value after 10 days and the synthetic wastewater (raw water) before the treatment of activated sludge were added. The COD value of the treated water after the treatment was measured. The results are shown in Tables 2 and 3. However, the COD value is 10
It is the average value for each day, and the alphabet in the reagent name represents the same compound name as in Test Example 1.

[0021]

[Table 2]

[0022]

[Table 3] Consideration on the results of Table 2 and Table 3 As for the results of Table 2, when the reagent A was added in an amount of 2 mg / l, the SVI after 10 days was 779 ml / g, which was lower than that in the case where no drug was added. It was recognized that In this wastewater treatment equipment, bulking occurs extremely easily,
Moreover, since the bulking state of the sludge does not end spontaneously, the decrease in the SVI of the sludge indicates that the reagent reagent A has a bulking suppressing effect at this addition concentration. Similarly, when the reagent A was added at 5 mg / l and 10 mg / l, the SVI after 10 days was 578, respectively, as compared with the case where no drug was added.
It was confirmed that it was lowered to ml / g and 443 ml / g. When 20 mg / l of reagent A was further added, SVI after 10 days
Was 158 ml / g, and it was confirmed that bulking was completely prevented. Therefore, the addition concentration of reagent A is 2 mg / l
It was confirmed that it had a bulking prevention effect at 10 mg / l.
As for the COD removal rate, in all cases, the removal rate was 90% or more, so when the addition concentration of the reagent A is at least 20 mg / l, it does not adversely affect the coexisting excellent sludge. I confirmed the thing.

The results in Table 3 are shown in Examples 2, 3,
As can be seen in Nos. 4 and 5, the reagent reagent A and the reagent reagent B are in the range of 5 to 7.5 mg / l in the reagent reagent A, and the total amount becomes 125 to 22.5 mg / l in the wastewater. If added as
The VI value was 547 ml / g to 244 ml / g, which was confirmed to be lower than that in the case where no drug was added. Therefore, the bulking suppressing effect was also confirmed by this addition method. In addition, as seen in Examples 1, 6, and 7, A alone added 10 mg / l, and A 10
Comparing the cases where mg / l and B were added at 7.5 mg / l and 15 mg / l, the SVI value was 23 when A was added alone.
In contrast to 1 ml / g, when both A and B were added, the SVI values became 74 ml / g and 79 ml / g, and A and B
When used in combination, a very remarkable synergistic effect was observed.
As seen in Comparative Example 9, when B alone was added at 30 mg / l, the SVI value was 85 ml / g. However, Example 6 (total amount of A and B is 17.5 mg / l) and Example 7
Compared with (the total amount of A and B is 25 mg / l), the values of SVI are similar, but the total amount of the drug is lower in Examples 6 and 7. It can be seen that by using B together, a remarkable synergistic effect can be seen. COD
Regarding the removal rate, in all cases, the removal rate was 90% or more, so that the reagent A and the reagent B coexist with excellent activity at a total addition concentration of at least 25 mg / l or less. It was confirmed that sludge was not adversely affected.

Test Example 3 [Test for confirming the effect of preventing bulking by using a cationic polymer flocculant together] In accordance with Test Example 2, 2-bromo-2-nitropropane-1,3-diol (name of reagent A) And a cationic polymer flocculant [reagent agent name K (polycondensate of amine-epichlorohydrin: 40 wt% aqueous solution having a molecular weight of 125,000)] were used to test the effect of preventing bulking. That is, Test Example 2
Using the synthetic wastewater prepared in 1., the aeration tank capacity of the experimental wastewater treatment apparatus of FIG. 2 was set to 2.3 l and the precipitation separation tank capacity was set to 7.7 l to cultivate the activated sludge, and the SVI value in the precipitation tank was determined. As the activated sludge, the sludge of a certain sewage treatment plant was acclimated with the above-mentioned synthetic wastewater for 2 weeks by the batch method. By this method, BOD load 0.8g / l · day, raw water BO
When the operation was carried out under the condition of D concentration of 760 mg / l, the SVI value of the activated sludge precipitated from the initial 140 ml / g changed to 400 ml / g or more bulking state after 24 days in accordance with the generation and growth of filamentous bacteria. Each reagent was added to the aeration mixing tank so that it would be a predetermined amount relative to the amount of synthetic wastewater (raw water), and the SVI value after 24 days and the COD value of the treated wastewater after treatment and the treated wastewater after activated sludge treatment It was measured. The results are shown in Table 4.

[Table 4]

Consideration on the results in Table 4 The results in Table 4 are obtained by combining the reagent agent A and the cationic polymer flocculant (reagent agent K) (test number 1) with the reagent agent A alone (test number). 2), the SVI value is smaller than in the cases where the reagent agent K alone (Test No. 3) and no agent are added, and it can be seen that the reagent agent A and the reagent agent K have a significant synergistic effect. In addition, since all the COD removal rates were 90% or more, it was confirmed that the reagent composition of 50 mg / l or less did not adversely affect the excellent activated sludge.

[0026]

The anti-bulking agent of the present invention comprises at least one of 2-bromo-2-nitropropane-1,3-diol and its lower fatty acid ester and / or a hydrogen peroxide-supplying compound and / or a high cationic content. By containing a molecular flocculant as an active ingredient, there is no adverse effect on excellent activated sludge, and bulking can be strongly suppressed for a long period of time.

[Brief description of drawings]

1 shows the MIC curve of the active ingredient of the invention against Sphaerotilus natans .

FIG. 2 shows a schematic diagram of an apparatus used in Test Examples 2 and 3.

[Explanation of symbols]

 1 Aeration mixing tank (continuous mixing culture tank) 2 Sedimentation separation tank 3 Air diffuser (air stone) 4 Air pump 5 Raw water storage tank 6 Raw water pump (quantitative roller pump) 7 Treated water 8 Partition plate

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takanobu Someoka 1-5-7 Kajimachi, Chiyoda-ku, Tokyo Environmental Engineering Co., Ltd. Katayama Chemical Industry Research Institute Co., Ltd. (No. 10-15) Yoshimasa Yamada, Inventor Yoshimasa Yamada 2-10-15 Higashi-Awaji, Higashiyodogawa-ku, Osaka City Katayama Chemical Industry Research Co., Ltd.

Claims (12)

[Claims] 1. A bulking inhibitor for activated sludge, comprising at least one of 2-bromo-2-nitropropane-1,3-diol and its lower fatty acid ester as an active ingredient. 2. An activated sludge containing at least one of 2-bromo-2-nitropropane-1,3-diol and its lower fatty acid ester and a hydrogen peroxide-supplying compound as active ingredients. Anti-bulking agent. 3. The bulking inhibitor according to claim 1, which further comprises a cationic polymer flocculant. 4. The bulking inhibitor according to claim 2, wherein the hydrogen peroxide supplying compound is hydrogen peroxide. 5. The cationic polymer flocculant has a molecular weight of 50,0.
The anti-bulking agent according to claim 3, which is a polycondensation product of 00-200,000 amine-epichlorohydrin. 6. A compounding ratio of at least one of 2-bromo-2-nitropropane-1,3-diol and its lower fatty acid ester and a hydrogen peroxide supplying compound is 5: 1 to 1: 500. Item 4. An anti-bulking agent according to item 2 or 3. 7. 2-Bromo-2-nitropropane-1,3-diol and at least one of its lower fatty acid esters and / or
The anti-bulking agent according to claim 3 or 5, wherein the compounding ratio of the hydrogen peroxide-supplying compound and the cationic polymer flocculant is 1: 0.4-10. 8. A method of treating organic matter-containing wastewater using activated sludge, comprising adding an effective amount of at least one of 2-bromo-2-nitropropane-1,3-diol and its lower fatty acid ester. Characteristic bulking prevention method. 9. The prevention method according to claim 1, wherein the added amount of at least one of 2-bromo-2-nitropropane-1,3-diol and its lower fatty acid ester is 2 to 20 mg / l with respect to the waste water. . 10. A method for treating wastewater containing organic matter using activated sludge, comprising 2-bromo-2-nitropropane-1,3-
A method for preventing bulking, which comprises adding an effective amount of at least one kind of diol and its lower fatty acid ester and a hydrogen peroxide supplying compound separately or simultaneously. 11. A ratio of at least one of 2-bromo-2-nitropropane-1,3-diol and its lower fatty acid ester and a hydrogen peroxide-supplying compound in a ratio of 5: 1 to 1: 500 (weight ratio). The prevention method according to claim 3, wherein 2 to 25 mg / l is added to the waste water as a total amount. 12. The method for preventing bulking according to claim 8, wherein an effective amount of a cationic polymer flocculant is added separately or simultaneously.