JPH07100483A - Method for treating activated sludge and treating agent for it - Google Patents

Abstract

PURPOSE:To provide a method for treating an activated sludge, suitable to form a sludge with excellent denseness and settling properties and provide a composite treating agent for it. CONSTITUTION:In this composite treating agent, an aerobic bacterium, a microorganism enzyme and a fibrous magnesium silicate clay mineral with a specific surface of 100 to 350 m<2>/g, an oil absorption of 100 to 300ml/100g and a fiber length of 5 to 20mum are combined to an activated sludge. Bulking phenomenon in the activated-sludge process can be prevented from occurring by combining this composite treating agent and a sludge floc with excellent denseness, settling properties and dehydration properties is formed and ordinary trouble in the method for the activated-sludge process is dissolved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sludge treatment agent for wastewater, and more particularly to a method for treating activated sludge suitable for forming sludge having excellent compactness and sedimentation property in the activated sludge treatment method and a method thereof. Regarding treatment agents.

[0002]

2. Description of the Related Art Conventionally, as a method for treating wastewater containing organic substances and the like discharged as municipal wastewater and industrial wastewater, useful microorganisms are propagated by blowing air by aeration and the like to form sludge flocs with high adsorbability to form wastewater. BOD, CO
A so-called activated sludge method is widely adopted, in which D is lowered and sludge flocs are settled to treat wastewater. Therefore, conventionally, in sludge, inorganic flocculant, organic polymer flocculant,
It has been practiced to improve the cohesiveness, sedimentation property, compactness or dehydration property of sludge flocs by adding an organic matter decomposing enzyme, an inorganic porous material and the like.

[0003] For example, Japanese Patent Laid-Open No. 1-99696 discloses adding a enzyme that decomposes a hardly-degrading protein that constitutes a proliferating microbial cell present in raw sludge to prevent the bulking phenomenon due to the propagation of filamentous bacteria. It is described to do. In addition, JP-A-62-186997 and JP-B-62
JP-A-46237 describes that an activated sludge in the state of bulking is used in combination with an inorganic porous material that adsorbs microorganisms and an organic polymer flocculant to improve the sludge flocculation and separation effects. .

[0004]

However, conventionally, in the wastewater treatment by the activated sludge method, the treatment conditions are not suitable and a large number of filamentous bacteria multiply, which causes a so-called bulking phenomenon and the sludge flocs become bulky. Sludge flocs are finely dispersed and do not aggregate, and sludge flocs with high viscosity and lack of compactness are formed, causing various troubles such as sedimentation of flocs and deterioration of compactness. ing. as a result,
The capacity of wastewater treatment is significantly reduced, and the treated water BOD, C
The reality is that the OD cannot be lowered sufficiently and a fundamental solution has not yet been made.

Therefore, an object of the present invention is to add aerobic bacteria and / or microbial enzymes to activated sludge,
Prevents overproliferation of filamentous bacteria without lowering the activity of sludge and prevents the so-called bulking phenomenon, while contacting fibrous magnesium silicate clay mineral in sludge, it is excellent in compactness and sedimentation Another object of the present invention is to provide a method for treating activated sludge, which is characterized by forming sludge flocs.

Another object of the present invention is to use aerobic bacteria and / or microbial enzymes for the above-mentioned method for treating activated sludge,
There is provided a treatment agent for activated sludge, which comprises a combination of a nutrient for aerobic bacteria and a fibrous magnesium silicate clay mineral.

[0007]

According to the present inventors, microbial bacteria such as sepiolite and attapulgite, which are so-called fibrous inorganic porous materials having a three-dimensional chain-like structure among various inorganic carriers, can be used. It was found that when added to an organic dispersion in which the organic matter flourishes, the dispersion aggregates and the organic matter settles together with sepiolite. As a result of diligent studies on whether this finding can be used for treatment of activated sludge, the inventors have found that sludge flocs having excellent sedimentation properties can be obtained, and have reached the present invention.

According to the present invention, (A) an aerobic bacterium, (B) a nutrient for (A) consisting of nitrogen, phosphorus and potassium components, and (C) a microbial enzyme are added to the activated sludge as required. The sludge mixture system formed by adding (D) BE
A method for treating activated sludge and a treating agent therefor, which comprises contacting a fibrous magnesium silicate clay mineral having a T method specific surface area in the range of 100 to 300 m ^ 2 / g to precipitate the sludge mixture. To be done.

In the most preferred embodiment of the present invention, (A), (B) and (C) are pre-packed in one pack in order to improve the handling property of the treatment method of the present invention for activated sludge. It is provided to use the treatment agent in combination with (D). Furthermore, more preferably (A),
It is provided to use a one-pack type composite treating agent in which (B) and (C) are carried on (D).

[0010]

The method for treating activated sludge of the present invention comprises adding aerobic bacteria and / or microbial enzymes to the activated sludge in order to solve the instability of the sludge that the activated sludge method normally has. , Without reducing the activity of the sludge and without increasing the viscosity of the sludge, and preventing the overgrowth of filamentous bacteria, to a sludge system in which the so-called bulking phenomenon is prevented, or a sludge system in which the bulking phenomenon is being prevented. Then, activated sludge characterized in that the sludge is formed into flocs excellent in compactness, sedimentation property and dehydration property by contacting the sludge system with fibrous magnesium silicate clay mineral sepiolite etc. Is the processing method of.

The purpose of this wastewater treatment is to form activated sludge into sludge flocs that are easy to settle, and to make the formed sludge flocs dense and easy to dehydrate. The main role of this activated sludge treatment method used in sewage treatment plants and wastewater treatment plants is microbial enzymes that decompose organic components in organic wastewater. Therefore, in this activated sludge treatment method, it is particularly important to prevent the so-called bulking phenomenon by adjusting so that the activity of the sludge is not lowered and the filamentous bacteria are not overgrown as described above. It is an important issue to solve the problems of treatment methods. The reason is that if such measures are effectively applied to activated sludge, it is easily expected that the effect will facilitate sludge settling, prevent sludge outflow from common settling tanks, and prevent persistent decomposition. Since components and the like are prevented from flowing into the treated water, it is therefore necessary to pre-treat the activated sludge in advance so that the bulking phenomenon does not occur.

However, it can be said that it is extremely difficult to artificially control this wastewater treatment step because the above-mentioned shaving activated sludge treatment method is a microbial treatment. In the present invention, in order to solve this problem, (A) an aerobic bacterium, (B) a nutrient for (A) consisting of nitrogen, phosphorus and potassium components, and (C) a microbial enzyme are added to the activated sludge. The step of adding is the above-mentioned pretreatment adjustment to properly stabilize the activated sludge, and the sludge mixture thus stabilized (D) has a BET specific surface area of 100 to 300 m ^ 2 / When fibrous magnesium silicate clay minerals such as sepiolite and attapulgite in the range of g are brought into contact with each other, the sludge mixture agglomerates and the sludge flocs to settle.

The aerobic bacterium (A) in the present invention is for preventing the overproliferation of filamentous bacteria without lowering the activity of sludge. Further, the microbial enzyme (C) acts to decompose the hardly decomposable organic components contained in the activated sludge so as not to deteriorate the treated water quality. Further, the effects of (A) and (C) reduce the viscosity of sludge. Further, the nitrogen, phosphorus and potassium components (B) are necessary as nutrients for (A). Therefore, the first feature of the present invention is to stabilize the activated sludge by pretreatment adjustment made by previously combining the activated sludge with the above-mentioned functions.

Then, when this sludge mixture system is brought into contact with a fibrous magnesium silicate clay mineral such as sepiolite, a sludge flo having excellent compactness, sedimentation and dehydration properties is formed. It is a feature.

Fibrous magnesium silicate clay minerals such as sepiolite and attapulgite used in the present invention are
It has a three-dimensional chain structure, and unlike two-dimensional crystal structures such as talc, the voids formed in the chain structure have a BET specific surface area of 100 to 350 m ^ 2 / g. It is a porous clay mineral that has a large specific surface area such that Unlike ordinary layered clay minerals represented by montmorillonite, which is also a porous clay mineral, sepiolite is also characterized in that it does not swell in water.

The second characteristic of the present invention can be well explained by the characteristic of such a sepiolite.
That is, being fibrous, the entanglement with the solid content of sludge is improved as compared with ordinary clay minerals, and sepiolite has a large specific surface area and is a porous clay mineral having an adsorption action. It can be said that sepiolite has a surface that is more likely to adsorb sludge solids than other fibrous materials. Therefore, although its details are unknown, these characteristic factors of the treatment agent of the present invention cause the sludge organic matter dispersed in the activated sludge to be aggregated, and the aggregated flocs become cores, and the cores are fibrous. Sludge with extremely excellent sedimentation properties, due to the fact that dense multi-stage flocs are formed by the entanglement with the solid content of sludge of clay minerals, and that the sepiolite itself is relatively heavy as shown in 2.4. Flock is formed (of Example 1 described later)

Refer to [Table 4]).

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The treatment agent of the present invention comprises (A) an aerobic bacterium, (B) a nutrient for (A) consisting of nitrogen, phosphorus and potassium components, (C) a microbial enzyme and (D).
When the activated sludge is treated with (A), it is composed of a combination with a fibrous magnesium silicate clay mineral having a BET specific surface area in the range of 100 to 350 m 2 / g.
As the order of adding (B), (C) and (D), (A), (B) and (C) are added first, and after the above-mentioned pretreatment adjustment is sufficiently made into activated sludge, The method of adding (D) is adopted. However, considering the handling property and the action and effect of each component, the most preferred embodiment of the present invention is that the sludge (A), (B) and (C) is pre-packed into one pack, and (D) is added to this. A method of using them in combination is adopted. Furthermore, more preferably (A),
A method of using (B) and (C) as a one-pack type composite treatment agent in which (D) is supported can also be adopted. Further, it is needless to say that the method of using the fibrous magnesium silicate clay mineral (D) alone is also adopted for sludge in which the bulking phenomenon is not a problem and so-called pretreatment adjustment is not required. However, considering the effect of lowering the viscosity of sludge, which is an additional action of (A) and (C), it is preferable to use (A) in addition to (A) for activated sludge in which the bulking phenomenon is not a problem. ), (B) and (C)
It is better to use in combination.

In the present invention, the component (A) is an aerobic bacterium (actinomycetes group), a nitrifying bacterium, or a general aerobic bacterium, and the microbial enzyme (C) is usually used by being contained in (A). However, it is an enzyme that decomposes the organic polymer that remains in the activated sludge.
Reduction of OD (of Example 1 described later)

(See Table 5)), for example, Protea
Zease, lysozyme, cellulase, amylase and the like are added for this purpose. In addition, since raw sludge contains a large amount of persistent proteins that constitute the microbial cells,
It is preferable to add zirconium, and depending on the type of other organic polymer contained in the sludge, for example,
It is also possible to use ze, amylase and the like together.

Furthermore, the fibrous clay mineral used as the component (D) is generally a two-layered porous fibrous mineral such as holmite mineral (sepiolite, attapulgite, palygorskite), halloysite, asbestos and the like. Layered fibrous minerals, or volcanic fibrous minerals including Kanuma soil and Akadama soil are used. If necessary, this fibrous clay mineral may be zeolite, or an adsorbent clay mineral typified by acid clay, cristobalite, quartz,
Rocks such as feldspar may be used together.

In the present invention, more preferably, fibrous clay minerals having a large specific surface area and adsorbability such as sepiolite and attapulgite are preferably used. For example, sepiolite is (OH2) 4 (OH) 4Mg8Si12O
It has a chemical composition of 30.6 to 8H2O, and a two-dimensional crystal structure such as talc forms a chain crystal structure like bricks stacked alternately. Such a three-dimensional chain clay mineral belongs to the montmorillonite group clay mineral, and is different from the layered clay mineral represented by bentonite having a three-layer structure in that it does not cause a swelling phenomenon. In addition, it is fibrous due to the pores formed in the chain-like gap, but unlike other fibrous minerals, it also has a large specific surface area and adsorptivity.

In the present invention, the specific surface area is 100 to 350 m ^ 2 / g and the oil absorption is 100 to 3
Sepiolite in the range of 00 ml / 100 g is preferably used. If the specific surface area is smaller than this range, the cohesive force of the sludge is small, while if it is larger than this range, no further effect can be obtained. The fibrous sepiolite used in the present invention generally has a fiber diameter of 0.1 to 3 μm.
m, and the fiber length is preferably 5 to 20 μm.
If the fiber length is smaller than this range, dense and sedimentary flocs are not formed, while if it is larger than this range, it becomes bulky like asbestos and floats on sludge to achieve the object of the present invention. Have difficulty.

Also below

Table 1 shows an example of the general chemical composition of sepiolite (dried at 110 ° C. for 2 hours).

[Table 1] General chemical composition of sepiolite SiO2 52.50 (wt%) Mg O22.8 Al2 O3 1.7 Fe2 O3 0.8 Ca O 0.8 H2 O ^ + 10.5 H2 O ^ -11.0

The sludge targeted by the present invention may be any sludge, for example, a bleaching step of dyeing, a starch manufacturing step, and a beer.
It can be used for an activated sludge treatment method in wastewater treatment such as food industry such as le, ramen, and quince, meat processing industry and paper industry such as paper and pulp. The blending amounts of (A) and (D) when blended and used in the sludge vary depending on the type of the aerobic bacterium of (A), but it is 100 to 600 ppm per activated sludge, especially 20
The solid content of the fibrous clay mineral (D) is preferably 300 to 1200 ppm, and more preferably 400 to 1000 ppm. If the blending amount of both components is less than the above range, it is difficult to form a sludge floc that is dense and has excellent sedimentation properties, while if it is more than the above range, no particular advantage is achieved. It is disadvantageous in terms of cost. Regarding (B) and (C), first, (B) is the nutritional supplement of (A), and its blending amount is 50 to 5
(C) added in the range of 00 ppm is 5 to 300
Used in the ppm range.

[0024]

Example 1 The treatment effect of the activated sludge having the following properties in the bleaching factory wastewater treatment was examined by using the treatment agent of the present invention.

[0025]

[Table 2] Properties of activated sludge Property Item Measurement value MLSS mg / l 3, 720 MLVSS mg / l 3, 132 SVI 207 COD ppm 308 PH 7.7 Transparency 3.9 Chromaticity 280

1 L of each of the above activated sludge was placed in each of 4 1 L capacity graduated cylinders.

Add each treating agent under the conditions of [Table 3], and use an air-pump to
Aeration was continued for days, and the progress of activated sludge during that period was the result.

[Table 4],

[Table 5],

The results are shown in [Table 6].

[0027]

[Table 3] Sludge treatment conditions [Amount of treatment agent added (mg / l)] Experiment number (A) agent (B) agent (D) agent 1 0 0 0 2 2 200 200 0 3 0 0 1, 1,000 4 200 200 1,000 (A) agent: general aerobic bacteria, nitrifying bacteria, radiobacterium group (C) agent microbial enzyme (protease, cellulase)
(B) agent containing: a microbial nutrient containing N and P elements,
(D) Agent: Sepiolite

[0028]

[Table 4],

[Table 5],

From the results shown in [Table 6], when comparing the characteristics of the activated sludge with time, the foaming of the sludge was found, as compared with Experiment 1 in which only aeration treatment was performed.
The combination of the treating agents of the present invention is effective in improving the sedimentation property of sludge flocs, the COD, the transparency of treated water, the chromaticity, and the like. In particular, as is clear from Experiment 4, the bulking phenomenon is caused. It is well understood that the sepiolite of the agent (D) acts as a settling accelerator of the sludge after the activated sludge has been subjected to pretreatment adjustment so as not to exist.

[0029]

[Table 4] pH and SV30 aeration days of sludge Before aeration 1st day 3rd day 7th day pH SV30 pH SV30 pH SV30 pH SV30 Experiment number 1 7.8 77 7.6 75 7.6 73 7.5 70 2 − − 7.8 70 7.6 60 7.3 54 3 − − 7.8 53 7.6 45 7.4 46 4 − − 7.8 50 6.5 43 6.3 45 SV30: Volume of sedimented sludge relative to volume of activated sludge slurry after 30 minutes of standing of activated sludge slurry

[0030]

[Table 5] COD and foaming status of sludge Aeration days 1st day 2nd day 4th day 7th day COD Foaming status COD Foaming status COD Foaming status COD Foaming status Experiment No. 1 80 × 60 × 52 × 48 × 2 67 × 54 × 41 ○ 39 ○ 3 70 × 55 × 43 △ 41 ○ 4 66 × 53 × 41 ◎ 33 ◎ Evaluation of firing condition ◎: No foam formation ○: Bubble formation but non-sticky transparent foam △: Bubbles occur, light brown foam x: Bubbles occur, viscous brown foam

[0031]

[Table 6] Sludge visibility and chromaticity Aeration days 7 days before aeration Fluorescence chromaticity Transparency Chromaticity Experiment No. 1 3.9 280 16.2 180 2 − − 28.6 60 3 − − 27.0 70 4 − − 30.0 40

[0032]

According to the present invention, activated sludge is treated with a combination of aerobic bacteria, microbial enzymes and fibrous magnesium silicate clay minerals such as sepiolite to prevent the bulking phenomenon in the activated sludge process. At the same time, sludge flocs having excellent compactness, sedimentation and dewatering properties are formed, so that the usual troubles in the activated sludge treatment method are eliminated.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Yohashi Tsuyoshi, 963-5, Sano, Katsuragi-cho, Ito-gun, Wakayama Prefecture (72) Masashi Kusumi, Masashi Kusumi, Wakayama, Wakayama

Claims (3)

[Claims] 1. In order to stabilize the activated sludge, if necessary, (A) aerobic bacteria, (B) nitrogen,
The sludge mixture system comprising a nutrient for (A) consisting of phosphorus and potash and (C) a microbial enzyme,
(D) BET method specific surface area of 100 to 350 m ^ 2 / g
A method for treating activated sludge, which comprises contacting fibrous magnesium silicate clay minerals in the range of 1 to settle the sludge. 2. The method for treating activated sludge according to claim 1, wherein the fibrous magnesium silicate clay mineral (D) has a fiber length of 5 to 20 μm. 3. (A) an aerobic bacterium, (B) nitrogen,
A nutritional supplement for (A) consisting of phosphorus and potassium components,
(C) Microbial enzyme and (D) BET method specific surface area is 100
A treatment agent for activated sludge, which is characterized by comprising a combination of fibrous magnesium silicate clay minerals in the range of up to 300 m ^ 2 / g.