JPH0671286A - Agent and method for preventive bulking - Google Patents

Abstract

PURPOSE:To easily and quickly prevent filiform bulking by combinedly using a small amount of flocculant and bactericide. CONSTITUTION:The bulking preventive agent for waste water treatment consists of the mixture of the chemicals (bactericide or antimicrobial agent) having sterilizing or bacteriostatic effect for the filiform micro-organism causing bulking and a cationic org. flocculant, and the chemical (bactericide or antimicrobial agent) having sterilizing or bacteriostatic effect for the filiform micro-organism causing bulking and a cationic org. flocculant are used in common for the waste water which causes or has caused bulking.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bulking inhibitor and a bulking inhibitor, and more particularly, a bulking inhibitor comprising a bactericide or antibacterial agent and a cationic organic flocculant, and a bulking inhibitor using the inhibitor. Regarding

[0002]

[Prior art and its problems]

(1) Conventionally, a method of using a bactericide or an antibacterial agent has been carried out as a method for suppressing bulking in activated sludge treatment, but the manifestation of the effect was unclear. In addition, if the allowable range of the concentration of the antibacterial agent is narrow and insufficient, no effect is observed, and conversely, if the amount is slightly increased, useful activated sludge microorganisms are killed or the activity is reduced, and other adverse effects on wastewater treatment are recognized. It was (2) Attempts have also been made to eliminate bulking by using a cationic organic coagulant, but this is only to be used as a coagulant, and the effect of just improving the sedimentation property in the sedimentation tank by aggregating the activated sludge. And was limited to first aid applications.

When a flocculant is added to the aeration tank of activated sludge, the sedimentation of activated sludge can be secured in the short term, but the floc of flocs is destroyed by mechanical force such as aeration, decomposition by microorganisms, or drainage. The effect of the flocculant is lost due to inactivation due to the reaction with the substance inside. Usually, the effect of improving the sedimentation property due to the aggregating agent disappears within 1 to 3 days at the longest, and the original bulking state is restored. Therefore, in order to prevent the bulking with the coagulant, it is necessary to add the coagulant continuously or periodically. This is because the coagulant remains in the activated sludge, which affects the water treatment performance such as deterioration of the quality of the treated water, reduces the effect of the coagulant itself, and increases the amount added, in addition to economic problems. It becomes a vicious circle. Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, and by using a small amount of a coagulant and a small amount of a bactericide together, it is possible to easily and quickly prevent filamentous bulking and a bulking inhibitor and a bulking agent. It is to provide a prevention method.

[0004]

The above object can be achieved by the present invention described below. That is, the present invention is characterized by comprising a mixture of a chemical agent (bactericidal agent or antibacterial agent) having a bactericidal or bacteriostatic effect against filamentous microorganisms causing bulking and a cationic organic flocculant. Anti-bulking agent in wastewater treatment, and a chemical (bactericidal agent or antibacterial agent) that has a bactericidal or bacteriostatic effect on filamentous microorganisms that cause bulking against the wastewater that causes bulking A method for preventing bulking in wastewater treatment, which is characterized by using an organic coagulant together.

[0005]

[Function] Each agent is used by combining an agent (bactericidal agent or antibacterial agent) having a bactericidal or bacteriostatic effect against filamentous microorganisms causing bulking with a cationic organic flocculant in an appropriate amount. Even if the amount is small, the occurrence of filamentous bulking can be easily and quickly prevented.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to the preferred embodiments. Examples of filamentous microorganisms such as filamentous bacteria or fungi on which the anti-bulking agent of the present invention effectively acts include Nostocoida filamentous bacteria.
limicola, Nocardia SP, Type 0041, Microthrix parv
icella, Thiothrix, Beggiatoa SP, Sphaerotilus natan
s, Type1701, Type1702, Type0411, Type1863, Type080
3, Type0961, Type021N, etc., and fungi include Saprolegnia ferax, Leptomitus lacreus, Mucor f
ragilis, Geotrichum candidum and so on.

The types of antibacterial agents or antibacterial agents used in the anti-bulking agent and the anti-bulking method of the present invention include the following agents. (1) Chlorine-based germicides such as coconut powder, high-grade coconut powder, hypochlorite, chlorine dioxide, chloramine T, and trichloroisocyanuric acid. (2) Peroxides such as hydrogen peroxide, sodium percarbonate and sodium pyrophosphate pyrophosphate. (3) Guanidine derivatives such as chlorhexidine salt, polyalkylene biguanidine salt and dodecyl guanidine salt. (4) Aldehyde compounds such as formalin, glyoxal, and glutaraldehyde. (5) Cationic surfactants such as benzalkonium chloride, benzethonium chloride and alkyl trimethyl ammonium salts. (6) Amphoteric surfactants such as alkyldi (aminoethyl) glycine hydrochloride and di (alkylaminodiethyl) glycine hydrochloride. (7) A water-soluble cationic polymer obtained by the reaction of dialkylamine and optionally ammonia (equimolar or less with dialkylamine) and epihalohydrin. (The above compounds have a relatively strong antibacterial action at a low molecular weight (molecular weight: about several thousand or less), and those having a molecular weight of 10,000 or more have been conventionally used as a cationic organic coagulant.
Also in the present invention, by using a low molecular weight compound having a molecular weight of several thousand or less and a high molecular weight compound having a molecular weight of 10,000 or more in combination, the synergistic effect as a bulking inhibitor, which is the object of the present invention, can be exhibited. )

(8) Phenolic compounds such as phenol, resorcin, phenol halogen compound, cresol, xylenol and diphenyl compound. (9) Organic nitrogen-sulfur compounds such as methylenedithiocyanate, dimethyldithiocarbamate, 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one. (10) 2,2-dibromo-2'-chloroacetophenone, 2,2-dibromoacetophenone, brommethylrodanate, dibromonitrosopropioamide, 2-heptadecyl-1-ethylethanolimidazolium bromide, 2,2 -Dibrom-3-
Organic brominated compounds such as nitrilopropioamide. (11) Sorbates such as potassium sorbate The above-mentioned bactericides or antibacterial agents may be used alone or in combination of two or more kinds. Depending on the type of filamentous microorganisms that cause bulking, the combined use of a plurality of fungicides or antibacterial agents produces a higher effect. Further, when there are a plurality of types of filamentous microorganisms generated, it is more effective to use a plurality of types of fungicides or antibacterial agents. The addition amount of the above-mentioned bactericidal agent or antibacterial agent is not particularly limited, but it is 5 times the minimum inhibitory concentration (MIC) to the minimum bactericidal concentration (MCC) of the filamentous microorganism (bulking-causing microorganism) that is occurring. It is effective to select the concentration between the concentrations corresponding to. At a concentration below the MIC, the object of the present invention may not be achieved. Choosing a concentration more than 5 times the amount of MCC enhances the effect of exterminating filamentous microorganisms that cause bulking, but at the same time adversely affects other useful activated sludge microorganisms, resulting in deterioration of treated water quality. Become.

In the present invention, the flocculating effect of the activated sludge by the cationic organic flocculant is high, and by forming a mechanically strong floc, it is possible to reduce the concentration of the bactericide or antibacterial agent added. Further, even if the concentration of the bactericide or the antibacterial agent becomes a value of MCC or more, the effect of the bactericide or the antibacterial agent on the useful activated sludge microorganism, which is the object of the present invention, is softened by using the cationic organic coagulant together As a result, a strong bactericidal or antibacterial action is exerted only on filamentous microorganisms. As a result, the bulking phenomenon can be eliminated and the quality of treated water can be prevented from deteriorating. When isolation of the bulking causative microorganism is difficult and MIC or MCC cannot be measured, if the target filamentous microorganism is a Gram-negative bacterium, MIC of Sphaerotilus natans
MCC value is Nocardia for Gram-positive filamentous bacteria
MIC / MCC value of SP is Geotrichum for fungi
By using the candidum MIC / MCC values as representative values, the addition amount can be calculated without causing a large error.

The types of main cationic organic flocculants used in the present invention are shown in the table below, but the present invention is not necessarily limited to these, and it is added to activated sludge to produce floc flocs. Any other structure may be used. Further, the type to be used may be single or plural, and it is preferable to select the conditions capable of forming the cohesive flocks as strong as possible according to the target activated sludge. As the amount of the cationic flocculant used,
It suffices to inject an amount that produces aggregate flocks. More preferably, the injection amount is strong and makes the flocks hard to break by mechanical force. The size of the flocks does not matter, it is important that they are not easily broken. Normal,
The amount added may be 0.01% by weight or more, and more preferably 0.08 to 4.0% by weight, based on the amount of dried sludge. Regarding the timing of addition of the bactericidal agent or antibacterial agent and the cationic organic coagulant, the bactericidal agent or antibacterial agent is usually added first or simultaneously with the coagulant. However, the object of the present invention can be achieved even if the aggregating agent is added first. When they are added separately, it is not preferable to set the addition intervals of the both too large, and the addition is usually performed within 24 hours. As the bactericidal agent, antibacterial agent or cationic organic coagulant, a single type may be used, or a plurality of types may be used. Multiple types of fungicides or antibacterial agents and / or cationic flocculants are used depending on the type of filamentous microorganisms causing the bulking, or if there are multiple types of filamentous microorganisms or depending on the properties of activated sludge. May be more effective.

The locations and methods for adding the bulking inhibitor of the present invention are as follows. (1) The bactericide or antibacterial agent and the cationic organic coagulant are used as the raw material (whether powder or liquid) or in an aqueous solution. Further, the bactericidal agent or antibacterial agent and the cationic organic coagulant may be used individually or in a mixture in advance.
For the purpose of improving the dispersion or solubility of these active ingredients, water-soluble inorganic salts such as sodium sulfate and sodium bicarbonate or diatomaceous earth powder, zeolite powder, surfactants, wetting agents, etc. may be used in combination or mixed. May be. (2) The order of addition to the activated sludge equipment to be treated is usually the simultaneous addition of a bactericide or antibacterial agent and a cationic organic coagulant, or first a bactericide or antibacterial agent, and then a cationic system. In many cases, an organic coagulant is added, and the effect of suppressing bulking is also good. However, the object of the present invention can be achieved by reversing the order of addition or simultaneously adding.
Further, when the drugs are added separately, it is preferable to complete the addition of all the drugs within 24 hours.

The above is a description of the case where the bulking inhibitor and the bulking prevention method of the present invention are mainly applied to activated sludge equipment which has already been in a bulking state. By applying the method of the present invention, it is possible to suppress the growth of filamentous microorganisms and prevent the bulking state. As a place to add the bulking inhibitor, it is generally added directly to the aeration tank or added to the returned sludge, and the effect is high, but mixing to the inflowing wastewater, addition to the sedimentation tank, etc.
It may be at any place. Also, other coagulants such as polyaluminum chloride, sulfuric acid band, secondary chloride
Inorganic flocculants such as iron, ferrous chloride, and polyiron sulfate, or sodium polyacrylate, acrylamide-sodium acrylate copolymer, polysulfomethylated polyacrylamide, polyacrylamide partial hydrolyzate, polyacrylamide, polyethylene A combination of anionic or nonionic polymer flocculants such as oxides is also useful for achieving the object of the present invention and can be used in combination if they are effective for producing a strong flocculation floc. The amount added is usually 0.003% by weight or more based on the amount of dry sludge, and more preferably in the range of 0.05 to 2.0% by weight. The timing of use is the same as, or before or after carrying out the present invention, and is not particularly limited, but the optimum timing differs depending on the properties of the activated sludge. However, in order to carry out the present invention, it is better to be close in time,
Add within 10 hours before and after practicing the present invention.

[0013]

EXAMPLES Next, the present invention will be described more specifically with reference to Examples and Comparative Examples. Glucose 720mg / L, starch 4
00 mg / L, peptone 320 mg / L, yeast extract 20 mg / L,
A synthetic wastewater consisting of 16 mg / L urea and 40 mg / L potassium phosphate was prepared. The pH of this synthetic wastewater is 8.1 and the TOC is 8.
50mg / L, COD is 820mg / L, BOD is 1,000mg
/ L, and as filamentous bacteria S. natans, TypeO21N, Tyo
It is a composition in which pe1701, Type0041, etc. are very likely to occur. Next, an experimental wastewater treatment device was assembled, and using this device and the above-mentioned synthetic wastewater, activated sludge was cultured and the SVI in the settling tank was determined. BOD load 0.4 by this method
When the operation was performed under the conditions of kg / m ³ · day and SRT 15 days, the above-mentioned filamentous bacteria of each type were generated and the SVI of the activated sludge increased from 110 to 20 days after the initial value according to the growth.
It became 50. Since the above results are extremely reproducible, the above-mentioned operation was repeated using the bulking inhibitor of the present invention to carry out the bulking inhibition method of the present invention as follows. The activated sludge was cultivated by the above method and the SVI was 4
The results and comparative examples of carrying out the method of the present invention when the time exceeds 00 are shown below.

[0014]

[Table 1] Fungicide or antibacterial agent: sodium hypochlorite aqueous solution (Na
OCl 5W / W% liquid) Cationic organic coagulant: Polymethacrylic acid ester-based strong cationic coagulant (molecular weight: about 3.5 million, granular). Addition method: A predetermined amount of each of them was simultaneously added to the aeration tank as it was. (Note) The addition amount is the amount (mg / L) in the form of solution or powder.

[0015]

[Table 2] Bactericide or antibacterial agent: 1,6-di (Np-chlorophenyl biguanide) hexazine gluconate aqueous solution (20 W / W%) Cationic organic coagulant: polymethacrylic acid ester type strong cationic coagulant (90W / W% powder, molecular weight about 35
0,000) Addition method: A predetermined amount of each of them was simultaneously added to the aeration tank as it was. (Note) The addition amount is the amount (mg / L) in the form of solution or powder.

[0016]

[Table 3] Bactericide or antibacterial agent: Glutaral, 1,5-pentanedial aqueous solution (C ₅ H ₈ O ₂ 20 W / W%) Cationic organic coagulant: Polyacrylamide with formalin and dimethylamine Cationic modified product (85 W / W% powder) Addition method: A predetermined amount of each of them was simultaneously added to the aeration tank as it was. (Note) The addition amount is the amount (mg / L) in the form of solution or powder.

[0016]

[Table 4] Bactericide or antibacterial agent: benzyldimethylammonium chloride aqueous solution (10 W / W% aqueous solution) Cationic organic flocculant: polyvinylpyridium chloride (90 W / W% powder, molecular weight of about 2 million) Addition method: Each of the above A predetermined amount was simultaneously added to the aeration tank as it was. (Note) The addition amount is the amount (mg / L) in the form of solution or powder.

[0017]

TABLE 5 disinfectant or antibacterial agents: alkyl di (aminoethyl) glycine hydrochloride solution _{(C 18 H 42 CL N 3} O 2 30W / W% liquid) cationic organic flocculants: polyacrylate strong cationic Flocculant (85W / W% powder, molecular weight about 200
10,000) Addition method: A predetermined amount of each of them was simultaneously added to the aeration tank as it was. (Note) The addition amount is the amount (mg / L) in the form of solution or powder.

[0018]

[Table 6] Bactericide or antibacterial agent: aqueous solution of a cationic polymer obtained from dimethylamine and epichlorohydrin (nonvolatile component 57 W / W% liquid, molecular weight about 050,000) Cationic organic coagulant: dimethylamine Aqueous solution of cationic polymer obtained from and epichlorohydrin (nonvolatile component 59 W / W% liquid, molecular weight about 250,000) Addition method: A predetermined amount of each solution was simultaneously added to the aeration tank. (Note) The addition amount is the amount (mg / L) in the form of solution or powder.

[0019]

[Table 7] Bactericide or antibacterial agent: aqueous phenol solution (C ₆ H ₆ O 2
0 W / W wt% liquid) Cationic organic coagulant: Polymethacrylic acid ester-based strong cationic coagulant (90 W / W wt% powder, molecular weight of about 3.5 million) Addition method: Aeration tank with each as above A predetermined amount was simultaneously added to.

[0020]

EFFECTS OF THE INVENTION The effect of the present invention is clear and reliable because the effect of inhibiting bulking is clear because it can kill or inhibit the growth of filamentous microorganisms that cause bulking. Further, it is possible to suppress the generation of filamentous microorganisms for one month or more with one treatment. The concentration selection range of the bactericide or antibacterial agent to be added is widened, the effect is recognized in a small amount, and conversely, even when a concentration exceeding the MCC value is added, the harmful effect on useful activated sludge microorganisms is reduced. As a result, the control of the added amount is dramatically facilitated.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shoichi Hirata 1-5-7 Kajimachi, Chiyoda-ku, Tokyo Within Environmental Engineering Co., Ltd. (72) Inventor Takanobu Someoka 1-Kagomachi, Chiyoda-ku, Tokyo 1- 5-7 Environmental Engineering Co., Ltd.

Claims (2)

[Claims] 1. A drug having a bactericidal or bacteriostatic effect on filamentous microorganisms that cause bulking (bactericidal agent or antibacterial agent).
An anti-bulking agent in wastewater treatment, which comprises a mixture of an organic solvent and a cationic organic coagulant. 2. A drug (bactericidal agent or antibacterial agent) having a bactericidal or bacteriostatic effect on the filamentous microorganisms causing bulking against the wastewater causing or causing bulking, and a cationic organic flocculant. A method for preventing bulking in wastewater treatment, which is characterized by using together with.