JP2811129B2 - Activated sludge treatment method and treatment agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, as a method of treating wastewater containing organic substances discharged as municipal sewage and industrial wastewater, useful microorganisms are propagated while blowing air by aeration or the like to form sludge flocs having a high adsorptivity, thereby forming wastewater. BOD, CO
The so-called activated sludge method, which lowers D and sediments sludge flocs to treat wastewater, is widely used. For that purpose, conventionally, sludge, inorganic coagulant, organic polymer coagulant,
It has been practiced to add an organic substance-decomposing enzyme, an inorganic porous material, etc. to improve the flocculation, sedimentation, denseness or dehydration of sludge floc.

[0003] For example, Japanese Patent Application Laid-Open No. 1-99696 discloses the addition of an enzyme for decomposing a hardly decomposable protein constituting a proliferating cell present in raw sludge to prevent a bulking phenomenon caused by propagation of filamentous bacteria. Is described. Further, Japanese Patent Application Laid-Open No. 62-186997 and Japanese Patent Publication No. Sho 62
No. 46237 describes that activated sludge in a bulking state is used in combination with an inorganic porous material that adsorbs microorganisms and an organic polymer flocculant to improve the flocculation and separation effects of the sludge. .

[0004]

However, conventionally, in the treatment of wastewater by the activated sludge method, the treatment conditions are not suitable, and a large number of filamentous bacteria multiply, causing the so-called bulking phenomenon, and the sludge floc is bulky. Sludge floc is finely dispersed and does not agglomerate, or sludge floc with high viscosity and lacks denseness is formed, causing various problems such as sedimentation of floc and reduction of denseness. ing. as a result,
Drainage treatment capacity is significantly reduced, and BOD and C
The fact is that the OD cannot be sufficiently reduced and a fundamental solution has not yet been achieved.

Accordingly, it is an object of the present invention to add an aerobic bacterium and / or a microbial enzyme to activated sludge,
Prevents the overgrowth of filamentous bacteria without reducing the activity of the sludge, while preventing the so-called bulking phenomenon, by contacting the fibrous magnesium silicate clay mineral in the sludge, excellent in denseness and sedimentation It is an object of the present invention to provide a method for treating activated sludge, characterized by forming sludge flocs.

Another object of the present invention is to provide an aerobic bacterium and / or a microbial enzyme for use in the above-described method for treating activated sludge.
It is an object of the present invention to provide a treating agent for activated sludge, which comprises a combination of an aerobic bacterial nutrient and a fibrous magnesium silicate clay mineral.

[0007]

According to the present inventors, among various inorganic carriers, so-called fibrous inorganic porous bodies having a three-dimensional chain structure, so-called sepiolite and attapulgite, are used as microbial bacteria. When added to an organic dispersion in which is prosperous, the dispersion was agglomerated and the organic substance settled out together with sepiolite. As a result of intensive studies as to whether this finding can be used for activated sludge treatment, the present inventors have found that sludge floc having excellent sedimentation properties can be obtained, and have reached the present invention.

According to the present invention, for activated sludge,
The sludge mixture system obtained by adding (A) an aerobic bacterium, (B) a nutrient for (A) composed of nitrogen, phosphorus and potassium components, and (C) a microbial enzyme, has (D) a BET specific surface area of 100 The present invention provides a method for treating activated sludge, comprising contacting a fibrous magnesium silicate clay mineral in a range of from about 300 m ² / g to sedimentation of the sludge mixture, and a treating agent therefor.

[0009] In the most preferred embodiment of the present invention, (A), (B) and (C) are pre-packaged to improve the handling of the activated sludge by the treatment method of the present invention. It is provided to use the treating agent in combination with (D). Still more preferably, (A),
It is provided to use a one-pack type composite treating agent in which (B) and (C) are supported on (D).

[0010]

The activated sludge treatment method of the present invention comprises adding an aerobic bacterium and / or a microbial enzyme to the activated sludge in order to solve the instability of the sludge normally involved in the activated sludge method. A sludge system in which the so-called bulking phenomenon is prevented, or a sludge system in which the bulking phenomenon is being prevented, without reducing the activity of the sludge and increasing the viscosity of the sludge and preventing the overgrowth of filamentous bacteria. Activated sludge characterized by forming a sludge into a floc excellent in denseness, sedimentation, and dehydration by contacting sepiolite, which is a fibrous magnesium silicate clay mineral, with the sludge system. Processing method.

The purpose of the wastewater treatment is to form activated sludge into sludge flocs that are likely to settle, and to make the formed sludge flocks dense and easy to dewater. The main role of this activated sludge treatment method used in sewage treatment plants and wastewater treatment plants is a microbial enzyme that decomposes organic components in organic sewage. Therefore, in this activated sludge treatment method, it is particularly necessary to prevent the so-called bulking phenomenon by adjusting the sludge activity without lowering the activity of the sludge and preventing the filamentous bacteria from growing too much as described above. This is an important issue to solve the problems of the treatment method. If such measures are effectively applied to activated sludge, it is easily expected that the effect of this measure is to promote sludge sedimentation, to prevent sludge from flowing out from common sedimentation tanks, and to reduce the difficulty of decomposition. Since the components and the like are prevented from flowing into the treated water, it is necessary to preliminarily adjust the activated sludge so as not to cause a bulking phenomenon.

However, since the activated sludge treatment method described above is a microorganism treatment, it is extremely difficult to artificially control this wastewater treatment step. In the present invention, in order to solve this problem, activated sludge is treated with (A) aerobic bacteria, (B) a nutrient for (A) comprising nitrogen, phosphorus and potassium components, and (C) a microbial enzyme. The step of addition is the above-mentioned pretreatment adjustment for correctly stabilizing the activated sludge, and the BET specific surface area (D) of the thus-stabilized sludge mixture is 100 to 300 m 2/2 /. When a fibrous magnesium silicate clay mineral such as sepiolite and attapulgite in the range of g is brought into contact, the sludge mixture is agglomerated, and the sludge flocs to settle.

In the present invention, the aerobic bacterium (A) is intended to prevent excessive growth of filamentous bacteria without reducing the activity of sludge. The microbial enzyme (C) acts to decompose the hardly decomposable organic components contained in the activated sludge so as not to deteriorate the quality of the treated water. Further, the viscosity of the sludge is reduced by the actions of (A) and (C). Further, the nitrogen, phosphorus and potash components (B) are necessary as nutrients in (A). Therefore, the first feature of the present invention is to stabilize activated sludge by pretreatment adjustment in which activated sludge is previously combined with the above functions.

The second aspect of the present invention is that when the sludge mixture system and the fibrous magnesium silicate clay mineral such as sepiolite come into contact with each other, a sludge flow excellent in denseness, sedimentation and dehydration is formed. It is a feature.

The fibrous magnesium silicate clay minerals such as sepiolite and attapulgite used in the present invention are:
Unlike a two-dimensional crystal structure such as talc, which has a three-dimensional chain structure, pores formed in the gaps of this chain structure have a BET specific surface area of 100 to 350 m ＾ 2 / g. It is a porous clay mineral having a large specific surface area and an adsorption effect. Sepiolite and the like are different from ordinary layered clay minerals typified by montmorillonite, which is also a porous clay mineral, and have a great feature that they do not swell in an aqueous system.

The features of the sepiolite can explain the second feature of the present invention well.
That is, the fibrous shape improves the entanglement with the sludge solid content as compared with the ordinary clay mineral, and sepiolite has a large specific surface area, and it is a porous clay mineral having an adsorption effect. It can be said that sepiolite has a surface on which sludge solids are more easily adsorbed than other fibrous materials. Therefore, although the details are unknown, these characteristic factors of the treatment agent of the present invention cause the sludge organics dispersed in the activated sludge to coagulate, and the coagulated flocs serve as nuclei. Sludge with extremely excellent sedimentation due to the fact that sepiolite itself is relatively heavy, as shown in the specific gravity of 2.4, due to the formation of dense multi-stage flocs due to the entanglement of the clay mineral with the sludge solids. It can be said that flocs are formed (see [Table 4] in Example 1 described later).

[0017]

Treatment agent of the present invention a preferred embodiment of the Invention, (A) aerobic Bakuteriya, (B) nitrogen, nutrient against the consisting of phosphorus and potassium components (A), (C) microbial enzymes and (D) B
The ET method is composed of a combination with a fibrous magnesium silicate clay mineral having a specific surface area of 100 to 350 m ² / g.
The order of adding (C) and (D) is (A),
(B) and (C) are added first, and after the above-mentioned pretreatment adjustment is sufficiently performed on the activated sludge, (D) is added. However, in consideration of the handling properties and the effect of each component, the most preferred embodiment of the present invention is to form (A), (B) and (C) into sludge in advance and pack (D) with sludge. The method used together is adopted. Still more preferably, a method in which (A), (B) and (C) are supported on (D) and used as a one-pack type composite treating agent can be adopted. In addition, for sludge which does not require the so-called pretreatment adjustment, in particular, the bulking phenomenon is not a problem, and it goes without saying that the method of using the fibrous magnesium silicate clay mineral alone (D) is also employed. However, in consideration of the additional effect of (A) and (C), ie, the effect of reducing the viscosity of sludge, it is preferable to use (A) for (D) especially for activated sludge in which the bulking phenomenon is not a problem. ), (B) and (C) are preferably used in combination.

In the present invention, the component (A) is an aerobic bacterium (actinomycete group), a nitrifying bacterium, or a general aerobic bacterium, and the microbial enzyme (C) is usually contained in (A). However, it is an enzyme that decomposes the organic polymer remaining in the activated sludge.
(See Table 5 in Example 1 below), for example, protease, lysozyme, cellulase, amylase, etc. are added for this purpose. In addition, since raw sludge contains a large amount of hardly degradable proteins constituting the proliferating cells, it is preferable to add a protease, and depending on the type of other organic polymer contained in the sludge, For example, cellulase, amylase and the like may be used in combination.

Further, the fibrous clay mineral used as the component (D) is generally a three-layer porous fibrous mineral such as a formite mineral (sepiolite, attapulgite, or palygorskite), or a two-layered material such as halloysite or asbestos. A layered fibrous mineral or a volcanic fibrous mineral including Kanuma soil, Akadama soil and the like is used. If necessary, this fibrous clay mineral may contain zeolite, or an adsorbent clay mineral represented by acid clay, cristobalite, quartz,
Rocks such as feldspar may be used in combination.

In the present invention, more preferably, a fibrous clay mineral having a large specific surface area and having adsorptivity, such as sepiolite and attapulgite, is suitably used. For example, sepiolite is (OH2) 4 (OH) 4Mg8Si12O
It has a chemical composition of 30-6-8H2 O and has a two-dimensional crystal structure such as talc forming a chain-like crystal structure as if bricks were alternately stacked. Such a three-dimensional chain clay mineral belongs to a montmorillonite family clay mineral, and is characterized by not causing a swelling phenomenon unlike a layered clay mineral represented by bentonite having a three-layer structure. Although it is fibrous due to the pores formed in the chain-shaped gaps, it is also characterized by having a large specific surface area and adsorptivity, unlike other fibrous minerals.

In the present invention, the specific surface area is in the range of 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 are preferably 5 to 20 μm.
If the fiber length is smaller than this range, dense and sedimentary flocs are not formed, while if larger than this range, it becomes bulky like asbestos and floats on sludge to achieve the object of the present invention. Have difficulty.

In Table 1 below, sepiolite (110
An example of the general chemical composition of a dried product at 2 ° C. for 2 hours) is shown below.

The sludge targeted by the present invention may be any sludge, for example, a bleaching step for dyeing, a starch production step, a beading step.
It can be used in the activated sludge treatment method in the wastewater treatment in the food industry, such as lumber, ramen, sweet potato, the meat processing industry, and the paper industry such as paper and pulp. The amount of (A) and (D) to be used in the sludge varies depending on the type of the aerobic bacteria of (A), but it is 100 to 600 ppm per activated sludge, and particularly preferably 20 to 20 ppm.
The content of the fibrous clay mineral of (D) is preferably 300 to 1200 ppm, more preferably 400 to 1000 ppm, as solid content per sludge solid content. If the blending amount of both components is less than the above range, it is difficult to form a sludge floc which is dense and excellent in sedimentation. It is disadvantageous in terms of cost. As for (B) and (C), (B) is the nutrient of (A), and its amount is 50 to 5%.
(C) is added in the range of 00 ppm to 5 to 300 ppm.
Used in the ppm range.

[0024]

(Example 1) For activated sludge having the following properties in bleached factory wastewater treatment,
The treatment effect of the treatment agent of the present invention was examined.

[0025]

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

Each 1 L of the above activated sludge is taken in four 1 L capacity measuring cylinders, each treating agent is added under the conditions shown in Table 3 below, and aerated continuously for 7 days with an air pump, and the activity during the period is increased. As a result of the progress of the sludge [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 100 000 200 000 400 200 200 1,000 (A) agent: a group of general aerobic bacteria, nitrifying bacteria, and radioacting bacteria, and microbial enzymes (proteases, cellulases) of agent (C)
(B) agent: a microbial nutrient containing N and P elements,
(D) agent: sepiolite

From the results shown in [Table 4], [Table 5], and [Table 6] , the properties of the activated sludge over time are compared with those of Experiment No. 1 in which only aeration treatment is performed. The effect of the combination of the respective processing agents of the present invention is exerted on the improvement of the transparency, COD and transparency of treated water, chromaticity, etc.
As apparent from Experiment No. 4, understand that acts sepiolite upon at (D) agent subjected to pre-pre-processing adjustments in the activated sludge so as not to cause bulking phenomenon as settling accelerator sludge Is done.

[0029]

[Table 4] Sludge pH and number of days of SV30 aeration Before aeration Day 3 Day 7 Day 7 pH SV30 pH SV30 pH SV30 pH SV30 Experiment No. 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 settled sludge 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. 180 × 60 × 52 × 48 × 2 67 × 54 × 41 ○ 39 ○ 370 × 55 × 43 △ 41 ○ 4 66 × 53 × 41 ◎ 33 ◎ Evaluation of the firing situation ◎: No bubbles generated ○: Transparent bubbles without bubbles but sticky △: Foam generation, light brown foam ×: Foam generation, sticky brown foam

[0031]

[Table 6] Permeability and chromaticity of sludge Days of aeration Day 7 before aeration Permeability Chromaticity Transparency Chromaticity Experiment number 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, the bulking phenomenon in the activated sludge method is prevented by treating activated sludge with a combination of aerobic bacteria, microbial enzymes and fibrous magnesium silicate clay minerals such as sepiolite. At the same time, sludge flocs having excellent denseness, sedimentation and dewatering properties are formed, so that ordinary troubles in the activated sludge treatment method are eliminated.

────────────────────────────────────────────────── ─── Continuation of the front page Examiner Nobuhito Saito (56) References JP-A-49-37473 (JP, A) JP-A-50-71586 (JP, A) JP-A-3-284400 (JP, A) 62-83011 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) C02F 3/12 C02F 1/52 C02F 11/02 B01D 21/01

Claims (3)

(57) [Claims] 1. An activated sludge for stabilizing sludge.
In (A) aerobic Bakuteriya, (B) a nitrogen, phosphorus and nutrients and (C) the sludge mixture system formed by adding a microbial enzyme to consist of potassium component (A), surface area (D) BET method specific A method for treating activated sludge, comprising contacting fibrous magnesium silicate clay mineral in the range of 100 to 350 m ² / g to settle sludge. 2. The activated sludge treatment method according to claim 1, wherein the fiber length of the fibrous magnesium silicate clay mineral (D) is 5 to 20 μm. (A) aerobic bacteria, (B) nitrogen,
Nutrient for (A) consisting of phosphorus and potash components,
(C) Microbial enzyme and (D) BET specific surface area is 100
A treatment agent for activated sludge, comprising a combination of fibrous magnesium silicate clay minerals in the range of from 300 m @ 2 / g.