JPH0957277A - Granulating and flocculating method of sewerage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the quantity of an amphoteric organic high molecular flocculant to be added by using the amphoteric organic high molecular flocculant made of a copolymer composed of monomers expressed by specific formulae as a 2nd flocculant in a method for granulating and flocculating by adding a 1st and the 2nd flocculant to a sewerage. SOLUTION: In the treatment of the sewerage, after the 1st and the 2nd flocculants are successively added to the sewerage and mixed, the sewerage is granulated and flocculated and the treated water is taken out. In such a case, the amphoteric organic high molecular flocculant made of the copolymer composed of the monomer expressed by formulae I-IV, in which total content of the monomers I and II is 15-40mol%, the ratio of the monomer I to total content of the monomers I and II is 0.1-0.5 and the content of the monomer III is 5-10mol%, is used as the 2nd flocculating agent. In the formulas, each of R<1> and R<3> expresses an alkyl group, each of R<2> and R4 expresses an alkyl group or a benzil group, each of R<5> and R<6> expresses hydrogen or methyl group, X expresses an anion and M expressed hydrogen or an alkali metal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for granulating and aggregating sewage, and more particularly to efficient granulation with a small amount of aggregating agent when adding an organic polymer aggregating agent to sewage for aggregating treatment. The present invention relates to a method of performing aggregation treatment.

[0002]

2. Description of the Related Art Conventionally, as a method for treating sewage, a method has been proposed in which most of suspended substances contained in sewage are removed by coagulation instead of a sedimentation basin.
Japanese Patent No. 98699 discloses a method of adding an inorganic coagulant to sewage and then adding an anionic organic polymer coagulant to perform coagulation treatment.

[0003]

However, although the anionic organic polymer flocculant is superior to the cationic organic polymer flocculant in the flocculation property of the suspended substance, the dehydration property of the obtained flocculate is not good. . Therefore, it is indispensable to use a cationic organic polymer coagulant during dehydration, and as a result, two kinds of coagulants are required, which is inconvenient in management.

On the other hand, the inventors of the present invention have already shown the aggregating property of the suspended substance equivalent to that of the anionic organic polymer aggregating agent, and
The dehydration property of the agglomerates was found to be an amphoteric organic polymer aggregating agent having specific composition and physical properties superior to those when a cationic organic polymer aggregating agent was used, and a patent application was previously filed (Japanese Patent Application No. 6-142).
No. 368), the amphoteric organic polymer flocculant requires a larger amount of addition at the time of flocculation than the anionic organic polymer flocculant, and a reduction in the amount added is required.

The present invention has been made in view of the above-mentioned conventional circumstances, and in the sewage granulation and aggregation treatment, the sewage production capable of significantly reducing the necessary addition amount of the amphoteric organic polymer aggregating agent. An object is to provide a method for aggregating particles.

[0006]

Means for Solving the Problems A method for granulating and aggregating sewage according to the present invention is to add a first aggregating agent to sewage and agitate it, then add a second aggregating agent and agitate, or , Introducing this sewage from the lower part of the granulation coagulation tank together with the second coagulant,
A method of granulating and aggregating sewage through a sludge blanket of the aggregating and aggregating tank, and removing treated water from the upper part of the aggregating tank, injecting the same aggregating agent as the second aggregating agent into the middle part of the aggregating and aggregating tank. In the method of granulating and aggregating sewage,
Which is a copolymer composed of monomers represented by the following general formulas (I), (II), (III) and (IV) as a flocculating agent of, wherein the total of the monomer (I) and the monomer (II) The content is 15 to 40 mol%, and the ratio of the monomer (I) to the total of the monomer (I) and the monomer (II) is 0.1.
To 0.5 and the content of the monomer (III) is 5 to
It is characterized by using an amphoteric organic polymer flocculant composed of a copolymer of 10 mol%.

[0007]

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In the method of the present invention, the sewage is first treated with
After the inorganic flocculant is added and mixed / stirred, the amphoteric organic polymer flocculant is added, or by introducing it together with the amphoteric organic polymer flocculant into the granulation flocculation tank, the suspended substance is flocculated / granulated. To do. Then, by adding an amphoteric organic polymer coagulant near the middle part of the sludge blanket layer in the tank, a stronger flocculate is formed and fine flocs are agglomerated to improve the removal rate of suspended matter. Higher and clear treated water can be obtained.

According to the method of the present invention, a specific amphoteric organic polymer flocculant is used for solid-liquid separation by adding the organic polymer flocculant to the sewage and sludge blanket method in the granulation flocculation tank. However, by adding this amphoteric organic polymer coagulant to at least two locations, where the sewage and the sludge blanket are mixed and near the middle of the sludge blanket layer, the amount of coagulant added is half that of the conventional method. Equivalent clear treated water can be obtained.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a flow chart showing an embodiment of the present invention. In FIG. 1, sewage is first stored in the flow control pond 1 through a screen (not shown). Reference numeral 1a is a submersible pump, and the pump 1a agitates the sewage in the regulating basin 1 so that the suspended matter does not settle. The sewage in the regulating pond 1 is introduced into the bottom portion of the reaction tank 3 through the pipe 2 equipped with the pump 2a and is stirred by the stirrer 3A. The inorganic coagulant in the auxiliary agent diluting tank 4 is injected into the reaction tank 3 as the first coagulant through the pipe 5 provided with the auxiliary agent injection pump 5a, and the sewage is sufficiently mixed with the inorganic coagulant. Mixed.

The sewage mixed with the inorganic coagulant is then
It is introduced into the bottom of the granulation flocculation tank 7 through the pipe 6. The amphoteric organic polymer aggregating agent in the polymer dissolving tank 8 equipped with a stirrer 8A is connected to the granulation aggregating tank 7 by a pipe 9 provided with a pump 9a.
Piping 9B including the pump 9b to the bottom of the tank via A
And is poured into the middle part of the tank, and the suspended substance in the sewage is agglomerated and granulated as the liquid is swirled by the rotation of the agitator 7A in the granulation agglomerating tank 7, It becomes a thing.

As the granulation and flocculation tank 7, a sewage inflow pipe containing an inorganic flocculant and an amphoteric organic polymer flocculant in the lower part or the bottom, or a sewage inflow pipe containing an inorganic flocculant and an amphoteric organic polymer flocculant is injected. A pipe and one or more amphoteric organic polymer coagulant injection pipes at an intermediate height of the tank, and
A tank with a clear water outlet opening at the top of the tank, which stirs the sewage and amphoteric organic polymer flocculant supplied in the tank with stirring blades inside the tank to agglomerate and granulate suspended substances In this case, any of them can be applied.

The liquid not aggregated in the granulation aggregating tank 7 is
The treated water overflows from the upper part of the granulation / aggregation tank 7, and the piping 10
It is sent to the treated water tank 11 via A. This treated water is further subjected to treatment such as chlorine sterilization according to the water quality standard of the discharge destination, and then discharged through a pipe 12 equipped with a treated water discharge pump 12A, or a higher-order treatment without chlorine sterilization. It is sent to a facility (not shown). On the other hand, the granulated agglomerate is extracted together with a small amount of liquid through the pipe (drainage pipe) 10B, and is supplied to a dehydrator (not shown) as it is or after removing the separated liquid, similar to the conventional method. It is then dehydrated. As the dehydrator, a conventionally used dehydrator such as a centrifugal dehydrator, a vacuum dehydrator, a belt press type dehydrator and a screw press can be used.

Examples of the sewage to be treated in the present invention include wastewater from ordinary households and specified business establishments, as well as effluent from the first settling basin of these effluents and effluent from the final settling basin after activated sludge treatment. .

The first flocculant used in the present invention is
Inorganic flocculants such as aluminum sulfate, polyaluminum chloride, ferric chloride and polyiron sulfate can be mentioned,
Of these, polyaluminum chloride is most preferable because it has excellent cohesiveness at a low addition amount as compared with other inorganic coagulants.

The addition amount of these inorganic coagulants as the first coagulant depends on the concentration of suspended substances in the sewage,
It is preferably about ³ to 10 g / m ³ -sewage in terms of Al or Fe conversion concentration. If the amount of such an inorganic flocculant is added, the pH of the sewage after the addition is 0.2 to 0.2 from the pH before the addition.
It only decreases by about 0.5.

On the other hand, the amphoteric organic polymer flocculant used in the present invention is composed of four kinds of monomers represented by the following general formulas (I), (II), (III) and (IV) (hereinafter, monomer (I ), A monomer (II), a monomer (III), and a monomer (IV)) as essential monomers and containing them in a composition ratio satisfying the following formulas (1) to (4).

[0019]

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15 mol% ≦ monomer (I) + monomer (II) ≦ 40 mol% 0.1 ≦ monomer (I) / (monomer (I) + monomer (II)) ≦ 0.5 5 mol% ≦ monomer ( III) ≦ 10 mol% Monomer (I) is a quaternary ammonium salt of dialkylaminoethyl methacrylate and monomer (II) is a quaternary ammonium salt of dialkylaminoethyl acrylate. R ¹ and R ^{3 in the} general formulas (I) and (II)
Are each an alkyl group having 1 to 4 carbon atoms, that is, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-
A butyl group, an isobutyl group, a sec-butyl group or a t-butyl group, R ¹ and R ³ may be the same,
They may be different from each other. R ² and R ⁴ are the above-mentioned alkyl groups having 1 to 4 carbon atoms or benzyl groups, and R ² and R ⁴ may be the same or different from each other.
X ⁻ is chlorine ion (Cl ⁻ ), bromine ion (Br ⁻ ),
Iodide ion (I ^-) halogen, such as ion, HSO ₄ ^{-,
_{SO 4 2- (1 / 2SO 4}} 2-), NO 3 -, CH 3 SO 4 -
And the like anion. In the general formulas (III) and (IV), R ⁵ and R ⁶ are hydrogen atoms or methyl groups, and M is hydrogen or an alkali metal such as Na or K.

Examples of the monomer (I) include methyl chloride quaternary product of dimethylaminoethyl methacrylate,
Examples thereof include benzyl chloride quaternary products of diethylaminoethyl methacrylate. Examples of the monomer (II) include methyl chloride quaternary product of dimethylaminoethyl acrylate and benzyl chloride quaternary product of diethylaminoethyl acrylate.

Examples of the monomer (III) include acrylic acid, methacrylic acid and salts thereof. Examples of the monomer (IV) include acrylamide and methacrylamide.

When the total content of the monomer (I) and the monomer (II) in the copolymer composed of these monomers (I), (II), (III) and (IV) is less than 15 mol%. The same applies when the removal rate of suspended solids decreases and exceeds 40 mol%. Further, when the ratio of the monomer (I) to the total of the monomer (I) and the monomer (II) is less than 0.1, the strength of the flocs produced is weak and the particles are immediately miniaturized. 0.
When it exceeds 5, the polymer becomes difficult to disperse. Further, if the content ratio of the monomer (III) in the copolymer is less than 5 mol%, the removability of suspended solids is lowered, and if it exceeds 10 mol%, the polymer becomes difficult to disperse.

The molecular weight of this copolymer is 1N-NaNO.
_{3 In an} aqueous solution, the intrinsic viscosity at 30 ° C. may be 8.0 dl / g or more, but in order to obtain a stable effect, the intrinsic viscosity should be 10.0 dl / g or more. Is preferred.

In the present invention, the amphoteric organic polymer flocculant comprising such a copolymer is added in an amount of 2 relative to sewage.
The ratio is preferably 10 to 10 g / m ³ , and 1.7 to 9 is preferable.
g / m ³ is mixed with sewage in advance and stirred, or introduced together with sewage from the lower part of the granulation and aggregating tank, and 0.3 to 1 g / m ³ is injected into the middle part of the granulating and aggregating tank, so that the total amount of It is preferable to adjust the addition ratio. In addition, in the present invention, the middle part of the granulation flocculation tank indicates a region where the sludge blanket layer is formed, and in general, the height of the granulation flocculation tank is 1/5 to 3 / from the bottom of the tank. The height position in the range of 5.

[0026]

The present invention will be described more specifically with reference to the following examples and comparative examples.

The organic polymer flocculants used in Examples and Comparative Examples are as shown in Table 1.

[0028]

[Table 1]

Examples 1 to 15 5 g-Al / m ³ of polyaluminum chloride was injected into the inflow sewage of the T sewage treatment plant of the following water quality, and the mixture was stirred and mixed in the reaction tank, and immediately after that, the diameter of 500 mmφ and height of 1500 mm In conducting the granulation and aggregation treatment by introducing it into the cylindrical granulation and aggregation tank, the amphoteric organic polymer flocculants (both-1, both-2, both-3) are shown in Table 2.
In the ratio shown in (1), the particles were separately injected into the sludge blanket layer at the bottom inlet of the granulation flocculation tank and the middle of the tank (at a position 60 mm from the bottom of the tank). The inside of the tank is agitated by two upper and lower agitating blades, the sludge blanket layer height is 1000 mm, and the clarified liquid depth is 5
It was operated at 00 mm and a sewage flow rate of 5 m ³ / hr.

Inflow sewage quality SS: 170 mg / l Turbidity: 105 degrees BOD: 165 mg / l COD _Mn : 103 mg / l In this treatment, the turbidity of the separated water discharged from the upper part of the tank is measured and suspended. The removal rate of the substance was calculated, and the results are shown in Table 2.

Examples 16 to 30 The amphoteric organic polymer coagulant was split-injected at the ratio shown in Table 2 into the granulation coagulation tank bottom inlet and the sludge blanket layer at two locations (positions 400 mm and 700 mm from the tank bottom). Except for the above, granulation aggregation treatment was performed in the same manner as in Example 1 to obtain the removal rate of suspended substances, and the results are shown in Table 2.

Comparative Examples 1 to 15 The granulating and aggregating treatment was carried out in the same manner as in Example 1 except that the amphoteric organic polymer coagulant was injected only at the bottom inlet portion of the granulating and aggregating tank at the ratio shown in Table 2. The removal rate of turbid substances was determined, and the results are shown in Table 2.

Comparative Examples 16 to 25 In place of the amphoteric organic polymer flocculant, the anionic organic polymer flocculant (A-1) was used in the proportion shown in Table 2 only in the granulation flocculation tank inlet portion (Comparative Examples 16 to 20). ), Or the inside of the granulation flocculation tank and the sludge blanket layer (600 mm from the bottom of the tank)
Granulation and agglomeration treatment was performed in the same manner as in Example 1 except that split injection (Comparative Examples 21 to 25) was carried out at two locations.
The removal rate of suspended matter was determined and the results are shown in Table 2.

[0034]

[Table 2]

The following is clear from Table 2.

That is, as is clear from the comparison between Examples 1 to 15 and Comparative Examples 1 to 15, the amphoteric organic polymer flocculant is dividedly injected, so that the same amount of the suspended substance is injected, rather than a single injection. The removal rate is high, and the amount of amphoteric organic polymer coagulant added to obtain the same suspended matter removal rate is 40-50%.
Could be reduced. Further, even when compared with the anionic organic polymer flocculants of Comparative Examples 16 to 25, the removal rate of suspended solids was increased with the same amount of flocculant added.

Considering the scale of the equipment, this result shows that in a facility with a throughput of 1000 m ³ / day, a batch injection (5 mg /
In the case of 1), the drug running cost is 273.75 million yen / year, and in the case of the split injection (3 mg / l) according to the present invention, it is 164.25 million yen / year, which is a cost of 10.95 million yen / year. It shows that it can be reduced.

[0038]

As described above in detail, according to the sewage granulation / aggregation method of the present invention, a specific amphoteric organic polymer is used in the granulation / aggregation treatment by adding a coagulant to the sewage by the sludge blanket method. By injecting the coagulant in a divided manner, the amount of the coagulant added can be reduced, the quality of the treated water can be improved, and the sewage can be efficiently treated at low cost.

[Brief description of drawings]

FIG. 1 is a flow chart showing an example method of a sewage granulation and aggregation method of the present invention.

[Explanation of symbols]

 1 Flow rate control tank 3 Reaction tank 4 Auxiliary agent dilution tank 7 Granulation and aggregation tank 8 Polymer dissolution tank 11 Treated water tank

Claims (1)

[Claims] 1. A first coagulant is added to sewage and stirred,
Then, after adding and stirring the second flocculant, or together with the second flocculant, this sewage is introduced from the lower part of the granulation flocculation tank, and the sewage is granulated and flocculated through the sludge blanket of the granulation flocculation tank. A method for treating and removing treated water from the upper part of the tank, comprising the step of granulating and aggregating sewage by injecting the same aggregating agent as the second aggregating agent into the middle part of the aggregating and aggregating tank. The following general formulas (I), (II), (II
A copolymer composed of monomers represented by I) and (IV), wherein the total content of the monomer (I) and the monomer (II) is 15 to 40 mol%, A high amphoteric organic compound consisting of a copolymer in which the ratio of the monomer (I) to the total of the monomer (II) is 0.1 to 0.5 and the content of the monomer (III) is 5 to 10 mol%. A method for granulating and aggregating sewage, which comprises using a molecular aggregating agent. Embedded image