JPH0671287A - Bulking canceling agent for activated sludge - Google Patents

Abstract

PURPOSE:To efficiently cancel bulking resulted from the generation of filiform micro-organism in a waste water treatment plant using activated-sludge process. CONSTITUTION:By adding the bulking canceling agent containing alkyl pyridinium halide as an effective component to an activated-sludge treatment plant in 0.05-5 pt.wt. per 100 pt.wt. solid matter of activated sludge, the filiform micro-organism is sterilized and the bulking of the activated sludge is canceled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bulking eliminator for activated sludge in a wastewater treatment system.

[0002]

2. Description of the Related Art The activated sludge method has been widely adopted as a method for treating wastewater containing organic substances such as general domestic wastewater and factory wastewater. The activated sludge method uses an aeration process that absorbs and decomposes and removes organic matter by contacting the wastewater to be treated with activated sludge, which is an aggregate of microorganisms, and the activated sludge is treated from the treated water using the difference in specific gravity between the treated water and the treated water. It is composed of a separation process for sedimentation separation. However, the activated sludge expands in the treatment process, and the specific gravity of the sludge with respect to the treated water decreases, so that the phenomenon that the treated water and the activated sludge cannot be smoothly separated in the separation step frequently occurs.

Such a phenomenon is called bulking, and particularly when the cause of expansion is bulking due to the growth of filamentous bacteria, the sedimentation of the activated sludge is extremely lowered, and when the sludge becomes terrible, the sludge becomes treated water. At the same time, there is a risk that not only the water will be spilled out but water pollution at the discharge destination will occur, but also continuous use of the wastewater treatment device will be impossible.

As a method of eliminating such bulking, a method of adding urea or amino acids in order to prevent abnormal growth of filamentous bacteria in activated sludge of wastewater treatment (Japanese Patent Laid-Open No. 52-8665), Alternatively, a method has been proposed in which urea and sodium phosphate are added to prepare nitrogen and phosphorus. However, these methods have drawbacks in that the treatment requires a long period of time, the cost of the drug is high, and the effect is unclear.

Further, a method of adding bentonite, cristobalite or the like in order to settle suspended matter in sludge (JP-A-60-175599), or ferric chloride, polyaluminum chloride and cationic polymers, etc. A method of adding a coagulant is known. Although these methods have a rapid improving effect on sedimentation property, they do not have a bactericidal action against filamentous bacteria and therefore do not lead to a fundamental solution. It had the drawback of having to be used.

Further, as a method of eliminating bulking by sterilizing filamentous bacteria, a method of adding a mixture of chlorhexidine hydrochloride, gluconic acid and chlorhexidine (Japanese Patent Publication No. 1-37364), dialkylamine, ammonia and epihalohydrin Method of adding water-soluble cationic polymer obtained by reaction with polyalkylene polyamine and epihalohydrin (JP-A-63-218299 and JP-A-2-169096)
However, in order to maintain an effective concentration at which any of these agents exerts the bactericidal effect of filamentous bacteria, it is necessary to continuously add a large amount of the agent, and other useful activated sludge fungi. In addition to exhibiting a bactericidal effect, there were problems in environmental impact and economical efficiency.

In addition to the above, as a method of eliminating bulking, a method of adding chlorine gas, sodium hypochlorite, hydrogen peroxide or ozone is also known, but chlorine gas is highly toxic and difficult to handle. Since these chemicals also have an adverse effect on the microorganisms in the activated sludge, it is difficult to calculate the input amount at the time of use and specialized knowledge is required, so it has not been widely spread. is the current situation.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a chemical agent capable of eliminating bulking by using a small amount of the chemical agent and eliminating the bulking agent without affecting the microorganisms in the activated sludge and the treated water. It is in.

[0009]

[Means for Solving the Problems] In view of such circumstances, the present inventors extensively collected activated sludge in which bulking has occurred and conducted various tests. As a result, the alkylpyridinium halide was tested against filamentous bacteria. It was found that the bactericidal action is effective in eliminating bulking, and that it does not affect the microorganisms in the activated sludge and the treated water, and the present invention has been completed.

The alkylpyridinium halide used in the present invention is represented by the general formula shown in Chemical formula 1, and representative examples thereof include ethylpyridinium bromide, n-butylpyridinium chloride, dodecylpyridinium chloride, Hexadecylpyridinium chloride, hexadecylpyridinium bromide and the like can be mentioned. These alkylpyridinium halides are obtained by reacting alkyl chloride with pyridine under heating and stirring,
After completion of the reaction, the product is obtained by subjecting the product to steam distillation to remove unreacted pyridine and recrystallization.

[0011]

[Chemical 1]

In the use of the bulking elimination agent of the present invention, whether the powdered bulking elimination agent is directly added to the activated sludge in the aeration tank of the activated sludge treatment device in which filamentous bulking is generated, the returning sludge line, etc. A method in which a solution in which a bulking canceling agent is dissolved in water is dropped or added, or an inorganic porous carrier is impregnated and added is used.

The amount of the bulking-eliminating agent added in the use of the bulking-eliminating agent of the present invention varies depending on the growth status of filamentous bacteria, but it is usually 0.1% based on 100 parts by weight of the dry solid content of the activated sludge. It may be added in an amount of 05 to 5 parts by weight. If the bulking eliminating agent added at this time is less than 0.05 parts by weight, it is difficult to eliminate the filamentous bulking because the bactericidal action against filamentous bacteria is low, and if it exceeds 5 parts by weight, activated sludge fungi are used. Is adversely affected and normal processing cannot be performed, which is not preferable.

[0014]

[Function] The filamentous bacterium that causes bulking has cells in the sheath that are the core of the filamentous bacterium covered by a sheath, and is less susceptible to external influences than general microorganisms.
In addition, since the sheath cells are destroyed and the sheath cells are actively activated even when they are released to the outside to reform the filaments, the sheath cells that are the nucleus of filamentous bacteria are killed in order to eliminate bulking. Need to let.

The bactericidal effect on the filamentous bacteria propagated in the activated sludge appears in 2 to 5 hours after the addition of the alkylpyridinium halide of the present invention, and destroys the cells of the filamentous bacteria regularly housed in the sheath. The appearance can be observed, and it can be observed that the sheath is cut at various places and released as fine fragments with the passage of time. As the filamentous bacteria are sterilized, the bulking is eliminated and the sludge index value showing the sedimentation property of the activated sludge (hereinafter, SVI: Sluge
The volume index) drops rapidly, and activated sludge is in a normal state with good sedimentation.

The alkylpyridinium halide of the present invention does not affect the activated sludge bacterium and can selectively kill filamentous bacteria. Alkylpyridinium halides are known to be excellent bactericides as quaternary salts, but it has not yet been elucidated about the phenomenon and the reason why filamentous bacteria in activated sludge can be selectively killed. Not in.

[0017]

【Example】

(Example 1) 10 liters of activated sludge in the combined treatment tank of the housing complex having a dry solid content (hereinafter referred to as MLSS) of the activated sludge of 1420 ppm and an SVI of 180 was put into an aeration tank having a capacity of 12.5 liters, and the amount of air While performing aeration at 7 liters / minute, artificial sewage adjusted to contain glucose 0.36 g / liter and polypeptone 0.12 g / liter was continuously added to the aeration tank at a rate of 10 liters per day using a metering pump. Then, when activated sludge was cultivated, Spherocillus natans grew, and after 6 days M
The bulking activated sludge has an LSS value of 1500 ppm and an SVI value of 650.

In this state, 40 mg of hexadecylpyridinium chloride monohydrate was uniformly added to the aeration tank, and 24 hours after this, the activated sludge had an MLSS value of 14
It was 00 ppm and the SVI value was 220. When the appearance of filamentous bacteria at this time was observed, it was found that the cells of Spherocillus natans contracted in the sheath, and some cells fell out of the sheath.

The activated sludge after 3 days has an MLSS value of 1660.
The ppm and SVI values were reduced to 140, and the activated sludge had a good sedimentation property. When the appearance of filamentous bacteria at this time was observed, the filamentous bacterial sheaths were cut at various places and became fragments, which were liberated from the flocs of the activated sludge. Most of the cells in the sheath were shed from the sheath.

The SVI value of the activated sludge after 6 days is 120 to 1
It was stable at 40, and the state of good sedimentation was maintained. When the appearance of filamentous bacteria was observed, new filamentous bacteria did not grow. Further, the water quality of the treated water during this test period had a BOD value of 20 ppm or less, and the addition of the bulking elimination agent of the present invention had no adverse effect on the treatment function.

(Example 2) Filamentous bacteria were cultured in the same continuous treatment system as used in Example 1, and Spherocillus natans and type 021N bulking sludge (MLS) were used.
S value: 1420 ppm, SVI: 520) were obtained. Next, 30 mg of dodecylpyridinium chloride was uniformly added to the aeration tank, and the culture of activated sludge was continued. The activated sludge after 18 hours had an MLSS value of 1300 ppm and an SVI value of 320. When the appearance of filamentous bacteria at this time was observed, the same state as in Example 1 could be confirmed.

The activated sludge after 3 days has an MLSS value of 1460.
ppm and SVI values are 180, and MLSS after 6 days
The value was 1670 ppm and the SVI value was 140. Filamentous bulking was eliminated and good sedimentation was maintained. In addition, the growth of new filamentous bacteria was not observed. The quality of treated water during this test period has a BOD value of 2
It was maintained at 0 ppm or less, and had no adverse effect on the processing function.

(Example 3) Filamentous bacteria were cultured in the same continuous treatment system as used in Example 1 to obtain Spherocillus natanus and type 021N bulking sludge (MLS).
S value: 1030 ppm, SVI: 920) were obtained. Next, 150 mg of n-butylpyridinium chloride was uniformly added to the aeration tank, and the culture of activated sludge was continued. 15
MLSS value of activated sludge after 1 hour is 1100ppm, SV
The I value was 460. When the appearance of filamentous bacteria at this time was observed, the same state as in Example 1 could be confirmed.

After 3 days, the MLSS value was 1240 ppm,
The SVI value is 240, and the MLSS value is 14 after 6 days.
10 ppm, SVI value was 160. Filamentous bulking was eliminated and good sedimentation was maintained. In addition, the growth of new filamentous bacteria was not observed. The quality of the treated water during this test had a BOD value of 20p.
The pm level was maintained, and there was no adverse effect on the processing function.

(Example 4) MLSS value is 1700 pp
m, SVI value of 230 10g of activated sludge of the combined treatment tank of the housing complex was put in the same treatment equipment as used in Example 1, while performing aeration, glucose 0.55g /
Liters and Ehrlich meat extract 0.12 g / liter of artificial sewage adjusted to be continuously added to the aeration tank at a rate of 10 liters per day using a metering pump,
When activated sludge was cultivated, types I-5 and II-4
(Filamentous bacteria are classified by Kono et al.) As bulking sludge with MLSS value of 1620ppm and SVI value of 52.
It became 0.

Here, 50 mg of hexadecylpyridinium chloride monohydrate was uniformly added to the aeration tank. The activated sludge 15 hours after the addition has an MLSS value of 1780 pp
m, SVI value was 340. When the appearance of filamentous bacteria at this time was observed, it was observed that the cells of types I-5 and II-4 were contracting in the sheath, and the bactericidal action against filamentous bacteria could be confirmed.

The activated sludge after 3 days has an MLSS value of 2020.
ppm and SVI values are 170, and MLSS after 6 days
The value was 2300 ppm and the SVI value was 140. Filamentous bulking was eliminated and good sedimentation was maintained. In addition, the growth of new filamentous bacteria was not observed. The quality of treated water during this test period has a BOD value of 2
It was maintained at 0 ppm or less, and had no adverse effect on the processing function.

(Comparative Example) In Example 1 and Example 4, the same treatment was carried out except that the bulking elimination agent of the present invention was not added, but no improvement in bulking was observed, and during the test period. The SVI value was 500 or more, and the sedimentation property remained poor.

[0029]

By using the bulking elimination agent of the present invention,
It is possible to eliminate bulking by adding a small amount of chemicals, and it is possible to eliminate bulking without affecting the microorganisms in the activated sludge and the treated water.

Claims (1)

[Claims] 1. A bulking elimination agent for activated sludge containing an alkylpyridinium halide as an active ingredient.