JP2528799B2 - Preventing bulking in wastewater treatment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing filamentous bulking by a filamentous bacterial growth inhibitor-producing microorganism, more specifically, culturing a specific filamentous bacterial growth inhibitor-producing bacterium belonging to the genus Acinetobacter , Fungus body,
The purpose of the present invention is to inhibit the growth of various filamentous bacteria and prevent filamentous bulking by using a culture or a culture-treated product.

[0002]

Filamentous bulking is a troublesome problem that frequently occurs in activated sludge treatment equipment, the cause of which is the overgrowth of specific filamentous microorganisms in the equipment. The microorganisms prevent the sludge from settling in the sludge separation tank,
There is a problem that sludge flows out together with the treated water, resulting in a significant decline in the treatment function of the treatment equipment. Heretofore, as methods for preventing the occurrence of the filamentous bulking, adjustment of air amount, reduction of sludge load amount, intermittent aeration method and the like have been proposed. In addition, as a measure after the occurrence of filamentous bulking, methods such as extraction of sludge, increase of dissolved oxygen concentration in aeration tank, introduction of initial sludge and addition of chemicals have been adopted. However, none of these methods was sufficient to prevent or suppress filamentous bulking.

[0003]

The conventional measures against filamentous bulking as described above are large-scale and require a lot of skill, and it is quite difficult to cope with rapidly growing filamentous bacteria. In addition, of the conventional measures against filamentous bulking, the addition of a drug has advantages such as quick response, quick effect and ease of application, but has various drawbacks in terms of sustainability and reaction specificity. Conventionally used chemicals are roughly classified into coagulants and bactericides. Of these, the coagulants require a large amount to be added, which increases the cost, increases the amount of sludge generated, and makes disposal of sludge difficult. . Further, the addition of the bactericide has a problem that even normal activated sludge is damaged and the treated water quality is temporarily deteriorated. Furthermore, since the bactericide easily flows out of the processing device,
There is a problem that it is not persistent and the addition must be repeated every time filamentous bulking occurs. In addition, the fact that the added bactericide remains in the sludge is a serious problem from the subsequent sludge treatment. Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art and to provide a method capable of easily and quickly preventing filamentous bulking without using a flocculant or a bactericide.

[0004]

The above object can be achieved by the present invention described below. That is, for the present invention, bulking occurs or resulting activated sludge mixture, Acineto
OS-4 strain belonging to the genus Bacter (FERM P-1
3284) or a culture thereof or a culture-treated product thereof, which is a method for preventing bulking in wastewater treatment.

[0005]

[Action] Bulking generated at the wastewater treatment plant due to the growth of various filamentous bacteria is removed from the treated wastewater by Acinetob.
OS-4 strain belonging to the genus Acter (FERM P-13
284) or its culture product or culture-treated product can easily and rapidly prevent the occurrence of filamentous bulking without using a flocculant or a bactericide which causes various problems.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to the preferred embodiments. In the present invention, a bacterium capable of producing a filamentous bacterial growth inhibitor is A cin.
It is a specific strain belonging to the genus Etobacter , and in the present invention, the strain is referred to as OS-4 strain (FERM P-1328).
4). Is the OS-4 strain, the activated sludge as a separate source, likely most produce filamentous bulking Sphaerot
ilus natans: KRN-A1 strain as the sole carbon source S. natans medium (KRN-A1 10
%), And the S. From the colonies formed in the Natans medium, GC medium (glucose 10 g, peptone 5
g, yeast extract 2.5 g and Agar 2%), 16 strains (OS-1 to 16) were isolated. This OS-1 ~ 1
After culturing each of the 6 strains in GS medium (excluding Agar) for several days, each was centrifuged and the supernatant was filtered through a sterilized filter to examine the growth inhibition of filamentous bacteria by the filtrate and investigated. The results are shown in Table 1 below.
It was discovered that only the OS-4 strain among the 1 to 16 strains exhibited a growth inhibitory action (bacteriolytic action) on filamentous bacteria, which was significantly different from other OS strains.

[0007]

[Table 1]

The morphological and physiological properties of the OS-4 strain are as follows.

[Table 2]

The above-mentioned culture and screening method is one example, and the present invention is not limited to this. Further, the growth culture of the isolated OS-4 strain may be a medium for culturing a normal microorganism, for example, a normal source containing a carbon source, a nitrogen source, an inorganic source, and more preferably an organic micronutrient. For example, glucose, maltose, sucrose, starch, oligosaccharide, dextran, or a sugar raw material containing them can be used. Further, a sugar raw material or the like containing them can be used. Alternatively, microbial cells of filamentous bacteria or activated sludge containing filamentous bacteria may be used as they are as a carbon source. As the nitrogen source, ammonium, nitrate, urea, meat extract, yeast extract, malt extract, bepton, various amino acids and the like are used. Cultivation is preferably carried out under aerobic conditions at a culture temperature of 1
The culture is adjusted to a temperature of 5 ° C. to 37 ° C. and a culture pH of 6.0 to 8.5, respectively, and cultivated with aeration or shaking for about 24 to 70 hours.

The culture and the culture-treated product which inhibit the growth of filamentous bacteria or lyse the same in the present invention include the above-mentioned culture solution or a treated product thereof, for example, a culture filtrate after removal of the cultured cells or ammonium sulfate. Alternatively, a crude enzyme powder obtained by adding an organic medium or the like, and a powder obtained by dissolving the powdered granules in water or a buffer solution to form a solution are also included. 0.5 ~ as dry weight
2.0% of various filamentous bacteria that cause filamentous bulking is suspended in water or a buffer solution (pH 6.5 to 8.5), and the above-mentioned culture or culture-treated product is added to the suspension at 30 to 37 ° C. 1-3
When allowed to act for a long time, the filamentous bacterium is easily growth-inhibited or lysed. The culture and the culture-treated product of the present invention exhibit growth inhibition or bacteriolytic action, for example, in the genus Sphaerotilus and the genus Begiatoa ( B
eggiatoa ), genus Thiothlix ( Thioth
rix ), and an unidentified bacterium, Eikelboom
(Water Res. Vol. 9, pages 365 + 388,
1975), Type 1701, 1
702, 021N, 0961, 1863 and so on. In particular, it is very effective against Type 021N, which is the most major cause of filamentous bulking in processing facilities around the world.

As a method for controlling filamentous bulking by using the microbial cell, culture, or culture-treated product of the filamentous bacterial growth inhibitor-producing bacterium of the present invention, the method and apparatus for administration as a drug to a treatment device can be used. There are two ways to incorporate these. First, in the case of administration, when there is a tendency for the sludge sedimentation index SV and SVI values to increase due to the growth of filamentous bacteria, or when the SV and SVI values have already increased, these Bulking can be eliminated and SV and SVI values can be lowered to the original level or lower by adding them to either the inflow drainage, the aeration tank or the sludge return pipe. In this case, an appropriate amount of addition is 0.005-1.0 by weight of the cultured cells or culture, and 0.005-by the weight of the treated culture with respect to the dry weight of activated sludge of 1.0.
1.0, and in combination with appropriate operating conditions, filamentous bacteria disappear completely and bulking disappears in 2-3 days.

Further, when microbial cells are added, these filamentous bacterial growth inhibitor-producing bacteria can be sufficiently grown in a normal nutrient medium as described above, and therefore remain in the aeration tank even after the bulking is eliminated. The filamentous bulking can be prevented for a long period of time. Next, when it is incorporated into a treatment device, it is necessary to immobilize the cultured bacterial cells or the treated culture product. For this, a physical adsorption method, a chair type method, a microcapsule type encapsulation method, or the like is effective. In the case of a culture treatment product that is a coarse powder, an adsorption method using an ionic bond or a covalent bond is also suitable. The biocatalyst thus fixed is fixed in the inflow pipe, the aeration tank, the sludge return pipe, etc., and the filamentous bulking can be permanently prevented.

[0013]

EXAMPLES The present invention will be described in more detail with reference to examples. Example 1 PGY medium (glucose 2.5 g) in a 20 ml test tube
Peptone (10 g, yeast extract 5 g) was dispensed in 2 ml aliquots, sterilized in an autoclave, and then 1, 2, 4, 6, 8 ml of a culture solution of OS-4 strain (sterilized with a sterile filter).
Add each. As a control, a medium (used for culturing the OS-4 strain) was added in an amount of 1, 2, 4, 6, and 8 ml, respectively.
Adjust the total volume to 10 ml with sterilized physiological saline. Pre-cultured S. natans: KRN-A1 and S
Y-1 (0.5 ml) was added, and the mixture was shake-cultured at 30 ° C. for 3 days. After the culture, the growth inhibitory activity of filamentous bacteria was measured based on the optical density at 600 nm, and the results are shown in FIG.

Example 2 Type 021N bacterial cells 10 g / l, yeast extract 2.5
g / l, bepton 5.0 g / l, KH ₂ PO ₄ 0.5
g _/ l, to prepare a medium (pH 7.0) consisting of _{MgSO 4 · 7H 2 O 0.2g /} l, and bacteria decreased autoclave. After cooling, the OS-4 strain was inoculated and shake-cultured at 30 ° C. for 24 hours. After culturing, the bacterial cells were removed from the culture broth with a centrifuge with cooling, and further filtered with a 0.45 μm membrane filter to obtain a culture filtrate. 1m of this culture filtrate
1 ml of a bacterial cell suspension containing a fragment of Type 021N filamentous fibers previously shortened with a homoblender and 0.
1 ml of 05M phosphate buffer (pH 7.0) was added to make the total volume 3 ml, and the mixture was reacted at 37 ° C. for 2 hours. As a control, 1 ml of water was added instead of the culture filtrate. The degree of 021N lysis was measured based on the reduction rate of the optical density (OD 600) at 600 nm, and the results are shown in Table 3.

Example 3 Of the medium composition used in Example 1, Type 021N was used.
After the cells were changed to glucose and autoclaved to sterilize, the same type of microorganism as in Example 1 was cultured, and the lytic activity of 021N was measured by the method according to Example 1. The results are shown in Table 3.

[Table 3]

[0016]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, it is possible to easily and easily use a small amount of cultured cells, cultures and treated products of OS-4 strain which is a filamentous fungus growth inhibitor-producing bacterium. Quick,
Moreover, it can lyse filamentous bacteria specifically and suppress filamentous bulking for a long period of time. Furthermore, by fixing these in the processing device, it is possible to permanently prevent filamentous bulking.

[Brief description of drawings]

FIG. 1 is a diagram showing the results of Example 1.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Osamu Koyama 1-5-7 Kajicho, Chiyoda-ku, Tokyo Environmental Engineering Co., Ltd. (72) Toyoichi Yokomaku 1-5-7 Kajimachi, Chiyoda-ku, Tokyo Environmental Engineering Co., Ltd. Examiner Motohiro Okubo

Claims (2)

(57) [Claims] 1. An OS-4 strain (FERM P-13284) belonging to the genus Acinetobacter or a culture or culture-treated product thereof is added to a mixture of activated sludge in which bulking occurs or has occurred. How to prevent bulking in wastewater treatment. 2. The method for preventing bulking in wastewater treatment according to claim 1, wherein the amount added is 0.005-1 with respect to 1.0 dry weight of activated sludge.