WO2018168447A1

WO2018168447A1 - Sludge dehydrating agent and sludge dehydrating method

Info

Publication number: WO2018168447A1
Application number: PCT/JP2018/007354
Authority: WO
Inventors: 詩歩子関口; 哲竹林; 佐藤　茂; 渡辺　実
Original assignee: 栗田工業株式会社
Priority date: 2017-03-14
Filing date: 2018-02-27
Publication date: 2018-09-20
Also published as: TWI743324B; TW201834976A

Abstract

Provided are: a sludge dehydrating agent having an excellent dehydrating effect, in particular, an excellent flocculation ability and gravity filtration property, even if an amount added is small; and a sludge dehydrating method using said sludge dehydrating agent. The present invention provides a sludge dehydrating agent and a sludge dehydrating method using the same, the sludge dehydrating agent comprising at least one crosslinked polymer selected from a polymer A, a polymer B, and a polymer C, which contain a monomer represented by a specific structural formula, wherein the crosslinked polymer has an intrinsic viscosity of 0.5-5.0 dL/g, as measured with 1.0 N sodium nitrate.

Description

Sludge dewatering agent and sludge dewatering method

The present invention relates to a sludge dewatering agent suitable for the dewatering treatment of sludge, particularly sludge that is difficult to dewater, and a sludge dewatering method using the sludge dewatering agent.

In general, cationic polymer flocculants are used for dewatering sludge mainly composed of excess sludge generated in food factories, chemical factories, human waste processing plants, and the like. However, with the recent increase in the amount of sludge generated and changes in sludge properties, dewatering is progressing, and improvement of dewatering effects such as gravity filterability is strongly demanded.

Conventionally, as a cationic polymer flocculant to be added to sludge, dimethylaminoethyl (meth) acrylate or its methyl chloride quaternized product has been mainly used, but in order to further improve the dehydration effect, In addition to treatment with a cationic polymer flocculant, for example, proposals as shown in Patent Documents 1 to 5 have been made.

Patent Document 1 describes that an ionic water-soluble polymer having a charge inclusion rate of 35 to 90%, which is obtained by granulating a water-in-oil emulsion liquid through a drying process, is used for sludge dewatering treatment.
Patent Documents 2 and 3 describe that an aggregating agent combining two types of cross-linkable water-soluble ionic polymers having a high charge inclusion rate and a low charge inclusion rate is applied as a sludge dehydrating agent. Yes.
Patent Document 4 discloses a sludge dehydrating agent based on a mixture of an amidine polymer, a crosslinked cationic polymer, and a non-crosslinked cationic polymer, and Patent Document 5 discloses an amphoteric polymer flocculant after adding an inorganic flocculant. A sludge treatment method in which is added is disclosed.

JP 2009-280649 A JP 2005-144346 A International Publication No. 2008/015769 JP 2011-224420 A Japanese Unexamined Patent Publication No. 63-158200

However, in the conventional techniques as described above, the sludge dehydration treatment cannot always be efficiently performed because the formed flocs are small or the adjustment of the addition balance of two kinds of chemicals is complicated.
Further, in Patent Document 3, since the cross-linked polymer is suppressed in molecular spreading in water due to cross-linking and exists in a “dense-packed” molecular form, a sludge dehydrating agent necessary for aggregating sludge is disclosed. There is a problem that the amount of addition increases. This is considered to mean that when the molecular spread of the sludge dehydrating agent is suppressed, that is, when the intrinsic viscosity is low, the sludge aggregation effect is inferior.
However, the mechanism of the relationship between the molecular spread of the polymer, which is a sludge dewatering agent, in water and the dehydration effect has not been fully clarified.

Therefore, the present inventors have repeatedly studied focusing on the relationship between the molecular spread of the crosslinkable polymer and the coagulation effect on sludge. As a result, it was found that a specific polymer exhibits an excellent dehydrating effect with a small addition amount.

That is, an object of the present invention is to provide a sludge dewatering agent excellent in dewatering effect, in particular, floc-forming ability and gravity filterability, and a sludge dewatering method using the sludge dewatering agent even if the amount added is small. .

The present invention is based on the finding that a dehydrating agent containing a specific cross-linked polymer and having a specific intrinsic viscosity exhibits excellent floc-forming ability and gravity filterability with a small addition amount. .

That is, the present invention provides the following [1] to [5].
[1] It contains one or more crosslinked polymers selected from the following polymers A, B and C, and the crosslinked polymer has an intrinsic viscosity at 30 ° C. in a 1.0 N sodium nitrate aqueous solution of 0.5 to 5 A sludge dewatering agent of 0.0 dL / g.
Polymer A: Crosslink in which the monomer composition of the polymer structural unit is 1-100 mol% of a cationic monomer represented by the following general formula (1) and 0-99 mol% of a nonionic monomer polymer

(In the formula (1), R ¹ represents .R ² and R ³ is a hydrogen atom or a methyl group are each independently an alkyl or alkoxy group having 1 to 3 carbon atoms, or .R ⁴ is a benzyl group , A hydrogen atom, an alkyl or alkoxy group having 1 to 3 carbon atoms, or a benzyl group, A is an oxygen atom or NH group, B is an alkylene group or alkoxylene group having 2 to 4 carbon atoms, X ^- is an anion).
Polymer B: Crosslink in which the monomer composition of the polymer structural unit is 1 to 100 mol% of a cationic monomer represented by the following general formula (2) and 0 to 99 mol% of a nonionic monomer polymer

(In Formula (2), R ⁵ and R ⁶ are each independently a hydrogen atom or a methyl group. X ⁻ is an anion.)
Polymer C: Anionic monomer having a monomer composition of a polymer constituent unit of 1 to 99 mol% of the cationic monomer represented by the general formula (1) and the following general formula (3) Crosslinked polymer comprising 1 to 99 mol% and nonionic monomer 0 to 98 mol%

(In the formula (3), R ⁷ is a hydrogen atom or CH ₂ COOY. R ⁸ is a hydrogen atom, a methyl group or COOY. Q is SO ₃ ⁻ , C ₆ H ₄ SO ₃ ⁻ , CONHC (CH ₃ ) _₂ CH ₂ SO ₃ ^- or COO ^- is .Y is a hydrogen atom or a cation).
[2] The sludge dehydrating agent according to the above [1], which is an emulsion liquid, or a dry granulated body or powder thereof.

[3] A sludge dewatering method in which the sludge dewatering agent according to [1] or [2] is added to sludge to dewater the sludge.
[4] The sludge according to [3], wherein the sludge dehydrating agent is used in combination with another polymer other than the crosslinked polymer, and the other polymer is a polymer having a cationic functional group or an anionic polymer. Dehydration method.
[5] In the polymer having a cationic functional group, the monomer composition of the polymer constituent unit is a cationic monomer represented by the general formula (1) and a cation represented by the general formula (2). 1 to 100 mol% of one or more cationic monomers selected from the ionic monomers, 0 to 99 mol% of the nonionic monomers, and the anionic property represented by the general formula (3) The sludge dewatering method according to [4] above, comprising from 0 to 50 mol% of a monomer.

According to the present invention, even if the addition amount is small, it is possible to provide a sludge dewatering agent that is excellent in the dewatering effect, in particular, the flock-forming ability and the gravity filterability. In addition, an efficient sludge dewatering method using the sludge dewatering agent can be provided.

Hereinafter, the sludge dewatering agent of the present invention and the sludge dewatering method using the sludge dewatering agent will be described in detail.
In the present specification, “(meth) acryl” means “acryl” and / or “methacryl (methacryl)”, and includes “(meth) acrylate” and “(meth) acrylo”. The same applies to the notation.

[Sludge dewatering agent]
The sludge dehydrating agent of the present invention contains one or more cross-linked polymers selected from Polymer A, Polymer B and Polymer C. The crosslinked polymer has an intrinsic viscosity of 0.5 to 5.0 dL / g at 30 ° C. in a 1.0 N sodium nitrate aqueous solution.
Such a sludge dehydrating agent exhibits a dehydrating effect such as excellent floc-forming ability and gravity filterability with an addition amount equal to or less than that of a conventional sludge dehydrating agent. The reason why an excellent dehydrating effect can be obtained is considered to be due to the following mechanisms (1) and (2).
(1) The crosslinked polymer having the intrinsic viscosity as described above is highly crosslinked and has a structure in which the molecule is rigid, and thus is not easily distorted. For this reason, the entire surface of the sludge particle is covered by strongly bonding to a plurality of crosslinked polymer molecules without covering the entire surface of the particle surface with one molecule of the crosslinked polymer. As a result, high-density bonds are formed between the sludge particles via the crosslinked polymer, and it is possible to form a hard floc that can withstand a strong share such as stirring.
(2) Further, the crosslinked polymer has a cationic charge trapped inside a highly crosslinked structure, and when a physical force such as stirring is applied, the trapped cationic charge is gradually released to the outside. Coarse flocs are easily formed by the sequential reaction between the cationic charge and the sludge particle surface.

(Crosslinked polymer)
The crosslinked polymer used for the sludge dehydrating agent is one or more selected from the following polymers A, B, and C. Among these, it may be used alone or in combination of two or more. Among these, it is preferable that the polymer A is included from the viewpoint of obtaining a more excellent dehydration effect. The cross-linked polymer is more preferably polymer A.

In addition to the crosslinked polymer, the sludge dehydrating agent may contain, for example, one or more compounds selected from the group consisting of powder acids such as sulfamic acid and salts such as sodium sulfate. However, from the viewpoint of the dehydration effect, the content of the crosslinked polymer in the sludge dehydrating agent is preferably 90% by mass or more, more preferably 95% by mass or more, and still more preferably 98% by mass or more. It is preferable that it is 100 mass%.

<Polymer A>
Polymer A has a monomer composition of a polymer structural unit represented by the following general formula (1): a cationic monomer (hereinafter simply referred to as “cationic monomer (1)”) 1 It is a crosslinked polymer composed of ˜100 mol% and nonionic monomer 0 to 99 mol%. The method for polymerizing these monomers to form a crosslinked polymer is not particularly limited, but a crosslinking agent is used as necessary.
In addition, the said crosslinking agent is not contained in the monomer composition of the polymer structural unit said by this invention.

In said formula (1), R < ¹ > is a hydrogen atom or a methyl group. R ² and R ³ are each independently an alkyl group or alkoxy group having 1 to 3 carbon atoms, or a benzyl group. R ⁴ is a hydrogen atom, an alkyl or alkoxy group having 1 to 3 carbon atoms, or a benzyl group. A is an oxygen atom or NH group, and B is an alkylene group or alkoxylene group having 2 to 4 carbon atoms. X ⁻ represents an anion, and preferably chlorine, bromine, iodine, ½ · SO ₄ ^— or CH ₃ SO ₄ ^— .

Examples of the cationic monomer (1) include (meth) acryloyloxyalkyl groups such as 2-((meth) acryloyloxy) ethyltrimethylammonium chloride and 2-((meth) acryloyloxy) ethyldimethylbenzylammonium chloride. Quaternary ammonium salts; (meth) acryloyloxyalkyl tertiary amine salts such as 2-((meth) acryloyloxy) ethyldimethylamine sulfate or hydrochloride, 3-((meth) acryloyloxy) propyldimethylamine hydrochloride, etc. And (meth) acryloylaminoalkyl quaternary ammonium salts such as 3-((meth) acryloylamino) propyltrimethylammonium chloride and 3-((meth) acryloylamino) propyltrimethylammonium methyl sulfate It is. Among these, it may be used alone or in combination of two or more. Of these, (meth) acryloyloxyalkyl quaternary ammonium salts are preferable, and 2- (acryloyloxy) ethyltrimethylammonium chloride is particularly preferable because it is excellent in polymerizability and easily obtains a crosslinked polymer having a strong structure. .

In the polymer A, the cationic monomer (1) is contained in an amount of 1 to 100 mol% as a polymer structural unit. That is, the polymer A may be all of the constituent monomer may be the cationic monomer (1), or the cationic monomer (1) may be non-ionic with 1 mol% or more and less than 100 mol%. It may be a copolymer composed of 99 mol% or less of a functional monomer. However, since the polymer in which the cationic monomer (1) is 100 mol% has high hygroscopicity, the polymer A is preferably a copolymer from the viewpoint of the dewatering effect and handling properties of the sludge dehydrating agent. The proportion of the cationic monomer (1) in the polymer constituent unit of the copolymer is preferably 30 to 95 mol%, more preferably 50 to 90 mol%, and still more preferably 55 to 85 mol%. %.

Examples of the nonionic monomer include amides such as (meth) acrylamide and N, N-dimethyl (meth) acrylamide; vinyl cyanide compounds such as (meth) acrylonitrile; methyl (meth) acrylate, (Meth) acrylic acid alkyl esters such as ethyl (meth) acrylate; vinyl esters such as vinyl acetate; aromatic vinyl compounds such as styrene, α-methylstyrene, and p-methylstyrene. These nonionic monomers may be used individually by 1 type, or may use 2 or more types together. Among these, acrylamide is preferable because it is excellent in water solubility, can easily adjust the monomer composition ratio in the polymer, and can easily obtain a crosslinked polymer having a strong structure.

<Polymer B>
In the polymer B, the monomer composition of the polymer structural unit is a cationic monomer represented by the following general formula (2) (hereinafter simply referred to as “cationic monomer (2)”) 1 It is a crosslinked polymer composed of ˜100 mol% and nonionic monomer 0 to 99 mol%. The method for polymerizing these monomers to form a crosslinked polymer is not particularly limited, but a crosslinking agent is used as necessary.

In the formula (2), R ⁵ and R ⁶ are each independently a hydrogen atom or a methyl group. X ⁻ is an anion, which is the same as in the general formula (1).

Examples of the cationic monomer (2) include diallyldimethylammonium chloride and dimethallyldimethylammonium chloride. Among these, it may be used alone or in combination of two or more.

In the polymer B, the cationic monomer (2) is contained in an amount of 1 to 100 mol% as a polymer structural unit. That is, the polymer B may be all of the constituent monomer may be the cationic monomer (2), or alternatively, the cationic monomer may be 1 mol% or more and less than 100 mol%. It may be a copolymer composed of 99 mol% or less of a monomer. From the viewpoint of the dewatering effect of the sludge dewatering agent, the polymer B is preferably a copolymer. The proportion of the cationic monomer (2) in the polymer constituent unit of the copolymer is preferably 30 to 95 mol%, more preferably 50 to 90 mol%, and still more preferably 55 to 85 mol%. %.
The nonionic monomer is the same as that for the polymer A described above.

<Polymer C>
Polymer C has a polymer composition unit monomer composition of 1 to 99 mol% of the cationic monomer (1) and an anionic monomer represented by the following general formula (3) (hereinafter referred to as “anion”). This is a cross-linked polymer composed of 1 to 99 mol% and nonionic monomer 0 to 98 mol%. The method of copolymerizing these monomers to form a crosslinked polymer is not particularly limited, but a crosslinking agent is used as necessary.

In the formula (3), R ⁷ is a hydrogen atom or CH ₂ COOY. R ⁸ is a hydrogen atom, a methyl group or COOY. Q is SO ₃ ⁻ , C ₆ H ₄ SO ₃ ⁻ , CONHC (CH ₃ ) ₂ CH ₂ SO ₃ ^— or COO ⁻ . Y is a hydrogen atom or a cation. Examples of the cation include alkali metal ions.

Examples of the anionic monomer (3) include vinyl sulfonic acid, vinyl benzene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, (meth) acrylic acid, itaconic acid, maleic acid, and alkali metals thereof. Salt. Among these, it may be used alone or in combination of two or more. Of these, acrylic acid is preferred.

The polymer C may be a copolymer of the cationic monomer (1) and the anionic monomer (3), or in addition to these monomers, nonionic monomers may also be used. It may be a copolymer as a polymer structural unit. The proportion of the cationic monomer (1) in the polymer constituent units of these copolymers is preferably 30 to 98 mol%, more preferably 50 to 97 mol%, and still more preferably 55 to 95 mol%. The proportion of the anionic monomer (3) is preferably 2 to 70 mol%, more preferably 3 to 50 mol%, still more preferably 5 to 45 mol%.
When the polymer C is a copolymer of the cationic monomer (1) and the anionic monomer (3), among the polymer constituent units of the copolymer, the cationic monomer (1) The ratio is preferably 30 to 98 mol%, more preferably 50 to 97 mol%, still more preferably 55 to 95 mol%.
When the polymer C is a copolymer of a cationic monomer (1), an anionic monomer (3), and a nonionic monomer, the ratio of the nonionic monomer is 1 to 65. It is preferably mol%, more preferably 5 to 50 mol%, still more preferably 10 to 35 mol%. Particularly preferred ratio ranges of the cationic monomer (1), the anionic monomer (3) and the nonionic monomer are 55 to 80 mol%, 5 to 15 mol%, and 10 to 30 respectively. Mol%.
The nonionic monomer is the same as that for the polymer A described above.

(Intrinsic viscosity)
The crosslinked polymer constituting the sludge dehydrating agent of the present invention has an intrinsic viscosity of 0.5 to 5.0 dL / g at 30 ° C. in a 1.0 N sodium nitrate aqueous solution.
Intrinsic viscosity is also an index of molecular weight, and the higher the molecular weight of the polymer, the higher the intrinsic viscosity. However, since the intrinsic viscosity is affected by the structure of the monomer that is a polymer constituent unit, polymerization conditions, and the like, it does not always correspond to the magnitude of the molecular weight.
In the present invention, among the crosslinked polymers, those having a specific intrinsic viscosity are used.

When the intrinsic viscosity is out of the above range, the formed floc diameter is hardly increased, the gravity filterability is inferior, and sufficient dehydration effect tends not to be obtained. From the viewpoint of obtaining a more excellent dehydrating effect, the intrinsic viscosity of the crosslinked polymer is preferably 0.8 to 4.9 dL / g, more preferably 1.0 to 4.5 dL / g, and still more preferably 1.2 to 4.5 dL / g.

The intrinsic viscosity is represented by [η] and is a value calculated using the following Huggins equation.
Huggins formula: η _SP / C = [η] + k ′ [η] ² C
In the above formula, η _SP : specific viscosity (= η _rel −1), k ′: Huggins constant, C: polymer solution concentration, η _rel : relative viscosity.
Prepare solutions of cross-linked polymers of different concentrations, determine specific viscosity η _SP for each concentration of solution, plot the relationship of η _SP / C versus C, and the value of the intercept extrapolating C to 0 is unique Viscosity [η].
The specific viscosity η _SP is determined by a method as shown in the following examples.

[Method for producing crosslinked polymer]
The cross-linked polymer can be produced by mixing and polymerizing a monomer that becomes a polymer constituent unit, a polymerization initiator, and a cross-linking agent as necessary.

Examples of the polymerization initiator include persulfates such as ammonium persulfate and potassium persulfate; organic oxides such as benzoyl peroxide; azobisisobutyronitrile, azobiscyanovaleric acid, 2,2′-azobis ( And azo compounds such as 2-amidinopropane) dihydrochloride and 2,2′-azobis (2,4-dimethylvaleronitrile).
The amount of the polymerization initiator used is usually about 0.001 to 0.1 mol% with respect to the total monomer amount.

Examples of the crosslinking agent include N, N′-methylenebis (meth) acrylamide, triallylamine, ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, and the like. Can be mentioned.
The addition amount of the crosslinking agent is adjusted so that the intrinsic viscosity of the crosslinked polymer is within the above range. Usually, it is preferably 50 to 500 ppm, more preferably 80 to 300 ppm, still more preferably 100 to 200 ppm based on the total monomer mass excluding the crosslinking agent.

The aspect of the polymerization method is not particularly limited, and examples thereof include an aqueous solution polymerization method, an emulsion polymerization method, and a suspension polymerization method. Among these, from the viewpoint of easy handling of the obtained crosslinked polymer and solubility in sludge, a production method obtained as an emulsion liquid is preferable, and a water-in-oil emulsion (W / O emulsion) is obtained by emulsion polymerization. It is more preferable to obtain a crosslinked polymer as a liquid.
In emulsion polymerization, for example, a mixed aqueous solution containing a monomer and water as a polymer constituent unit of a cross-linked polymer and a cross-linking agent as necessary is added to an oil layer mixture containing a surfactant and an oily solvent. It can be carried out by stirring and mixing to emulsify and adding a polymerization initiator thereto. By such a method, a crosslinked polymer is obtained as a W / O emulsion liquid.
As the oily solvent, for example, mineral oil such as kerosene and light oil and their refined products such as normal paraffin, isoparaffin, naphthenic oil, etc. can be used, and synthetic oils and vegetable oils having properties equivalent to these oils can be used. Animal oils or mixtures thereof can also be used.
Examples of the surfactant include sorbitan fatty acid esters such as sorbitan monooleate and sorbitan monostearate; and nonionic surfactants such as polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether and pentaoxyethylene oleyl ether. Preferably used.

Further, the crosslinked polymer obtained as such an emulsion liquid may be granulated or powdered by spray drying using a spray dryer or the like to obtain a dried granulated body or powder. If it is set as such a form, the handleability of a sludge dehydrating agent can be improved.

[Sludge dewatering method]
The sludge dewatering method of the present invention is a method in which the sludge is dehydrated by adding the sludge dehydrating agent to sludge such as excess sludge and mixed sludge from food factories, chemical factories, human waste treatment plants, and the like.
Since the sludge dewatering agent of the present invention can exhibit an excellent dewatering effect even in a small amount, the amount added to the sludge can be suppressed, and the operability of the dewatering treatment can be improved and the cost can be reduced. For example, when the suspended solid (SS) concentration is about 0.4 to 4.0% by mass, the amount of the sludge dehydrating agent added is preferably 20 to 1600 mg / L, more preferably 50 to 1200 mg / L. More preferably, it is 60 to 800 mg / L.

The method for adding the sludge dehydrating agent to the sludge is not particularly limited, and a known method for adding the sludge dehydrating agent can be applied. In general, the sludge dehydrating agent is added to the sludge as an aqueous solution or aqueous dispersion having a cross-linked polymer concentration of 0.01 to 0.5% by mass, preferably 0.03 to 0.3% by mass. In some cases, it may be added in a solid form such as powder.

(Combination with other polymers)
In the sludge dewatering method using the sludge dewatering agent of the present invention, the sludge dewatering agent and a polymer other than the crosslinked polymer may be used in combination. Examples of the other polymer used in combination include a polymer having a cationic functional group or an anionic polymer. The polymer having a cationic functional group includes not only a cationic polymer but also an amphoteric polymer. Further, the other polymer that can be used in combination may be a crosslinked type or a non-crosslinked type such as a straight chain, but from the viewpoint of sufficiently exerting the dewatering effect of the sludge dewatering agent, Those are preferred.
These other polymers are also preferably added to the sludge as an aqueous solution or aqueous dispersion having a polymer concentration of 0.01 to 0.5% by mass, like the cross-linked polymer of the sludge dehydrating agent, more preferably 0.03 to 0.3% by mass. In some cases, it may be added in the form of a solid such as a powder.

<Polymer having cationic functional group>
As the polymer having a cationic functional group, for example, the monomer composition of the polymer structural unit is one or more cationic monomers selected from the cationic monomers (1) and (2) ( Hereinafter, it is expressed as “cationic monomer (1) / (2)”.) 1 to 100 mol%, nonionic monomer 0 to 99 mol%, and anionic monomer (3) A polymer composed of 0 to 50 mol% can be used. The polymer may be a linear polymer, or may be a crosslinked polymer having an intrinsic viscosity outside the range of the intrinsic viscosity of the crosslinked polymer described above.
In the polymer having a cationic functional group, all of the constituent monomers may be cationic monomers (1) and (2). Alternatively, the cationic monomers (1) and (2 The copolymer may be composed of 1 mol% or more and less than 100 mol%, nonionic monomer 0 to 99 mol%, and anionic monomer (3) 0 to 50 mol%.

Specific examples of the cationic monomers (1) and (2) in the polymer having the cationic functional group include 2-((meth) acryloyloxy, similar to those mentioned for the polymer A or the polymer B. ) (Meth) acryloyloxyalkyl quaternary ammonium salts such as ethyltrimethylammonium chloride, 2-((meth) acryloyloxy) ethyldimethylbenzylammonium chloride; 2-((meth) acryloyloxy) ethyldimethylamine sulfate or hydrochloric acid Salts, (meth) acryloyloxyalkyl tertiary amine salts such as 3-((meth) acryloyloxy) propyldimethylamine hydrochloride; 3-((meth) acryloylamino) propyltrimethylammonium chloride, 3-((meth) Acryloylamino) Pills trimethylammonium (meth) acryloyl amino alkyl quaternary ammonium salts such as methyl sulfate, diallyl dimethyl ammonium chloride, di methacrylate dimethyl ammonium chloride. Among these, it may be used alone or in combination of two or more. Of these, (meth) acryloyloxyalkyl quaternary ammonium salts or (meth) acryloyloxyalkyl tertiary amine salts are preferred.

Specific examples of the nonionic monomer in the polymer having a cationic functional group include, for example, (meth) acrylamide, N, N-dimethyl (meth) acrylamide and the like, as described for the polymer A. Amides; vinyl cyanide compounds such as (meth) acrylonitrile; (meth) acrylic acid alkyl esters such as methyl (meth) acrylate and ethyl (meth) acrylate; vinyl esters such as vinyl acetate; styrene, α -Aromatic vinyl compounds such as methyl styrene and p-methyl styrene. Among these, it may be used alone or in combination of two or more. Of these, acrylamide is preferred.

Specific examples of the anionic monomer (3) in the polymer having a cationic functional group include, for example, vinyl sulfonic acid, vinyl benzene sulfonic acid, 2-acrylamido-2, as described for the polymer C. -Methylpropanesulfonic acid, (meth) acrylic acid, itaconic acid, maleic acid, and alkali metal salts thereof. Among these, it may be used alone or in combination of two or more. Of these, acrylic acid is preferred.

The polymer having a cationic functional group may be mixed with the sludge dewatering agent and added as a single solution, or may be added separately from the sludge dewatering agent simultaneously or sequentially. Good. The mass ratio of the sludge dehydrating agent to be used in combination with the polymer having a cationic functional group is preferably 20:80 to 80:20, more preferably 25:75 to 75:25, and still more preferably 30:70. ~ 70: 30.

<Anionic polymer>
Examples of the anionic polymer include sodium polyacrylate, polyacrylamide partial hydrolyzate, a copolymer of sodium acrylate and acrylamide, partially sulfomethylated polyacrylamide, acrylamide and (2-acrylamide) -2-methylpropanesulfone. And a terpolymer of acrylamide, sodium acrylate, and (2-acrylamide) -2-methylpropanesulfonate. Among these, a polyacrylamide partial hydrolyzate or a copolymer of sodium acrylate and acrylamide is preferable.

When the anionic polymer is used in combination with the sludge dewatering agent, it is preferably added after the sludge dewatering agent is added to the sludge. The mass ratio of the sludge dehydrating agent and the anionic polymer used in combination is preferably 50:50 to 95: 5, more preferably 60:40 to 90:10, and still more preferably 65:35 to 80:20. It is.

EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not restrict | limited by the following Example.
[Preparation of polymer]
Polymers (A1) to (A5), (B1) and (C1) used in the examples were produced by the following synthesis examples 1 to 7, respectively. Further, the polymers (Z1) and (Z2) used in the following comparative examples were produced by the following synthesis examples 8 and 9, respectively.
In Examples and Comparative Examples, commercially available polymers (Z3) to (Z9) were also used. The polymer (Z7) is a polyamidine flocculant.

(Synthesis Example 1) Synthesis of Polymer (A1) In a 1 L 4-neck separable flask equipped with a stirrer, a cooling tube, a nitrogen introduction tube and a thermometer, 312 g of normal paraffin, 25 g of pentaoxyethylene oleyl ether, and 25 g of sorbitan monooleate Was stirred and mixed to prepare an oil layer mixture.
Next, a mixed aqueous solution of 388 g of 80% by mass aqueous solution of 2- (acryloyloxy) ethyltrimethylammonium chloride (DAA), 28 g of acrylamide (AAM), 0.04 g of N, N′-methylenebisacrylamide as a crosslinking agent, and 222 g of pure water Was added to the oil layer mixture and emulsified by stirring with a homogenizer. This was adjusted to 50 ° C. with stirring, and nitrogen gas was blown into the liquid for 30 minutes. While flowing nitrogen gas in the gas phase, 2 g of a 2 mass% toluene solution of 2,2′-azobis (2,4-dimethylvaleronitrile) was added and polymerized at 45 to 55 ° C. for 8 hours to form a W / O emulsion. A crosslinked polymer was obtained as a liquid.
This emulsion liquid was spray-dried with a desktop spray dryer to obtain a crosslinked polymer (A1) as a powder having a water content of 5% by mass or less.

(Synthesis Example 2) Synthesis of Polymer (A2) In Synthesis Example 1, the amount of N, N′-methylenebisacrylamide added was 0.06 g, and spray drying with a spray dryer was not performed. In the same manner as above, a crosslinked polymer (A2) was obtained as a W / O emulsion liquid.

(Synthesis Example 3) Synthesis of Polymer (A3) In Synthesis Example 1, 349 g of an 80% by mass aqueous solution of 2- (acryloyloxy) ethyltrimethylammonium chloride (DAA) among the raw material composition added to the oil layer mixture, acrylamide ( AAM) was changed to 68 g, and N, N′-methylenebisacrylamide was changed to 0.05 g. Otherwise, the same procedure as in Synthesis Example 1 was carried out to obtain a crosslinked polymer (A3) as a powder having a moisture content of 5 mass% or less. It was.

(Synthesis Example 4) Synthesis of Polymer (A4) In Synthesis Example 1, the amount of N, N′-methylenebisacrylamide added was 0.035 g, and the rest was the same as Synthesis Example 1 except that the water content was 5% by mass or less. As a powder, a crosslinked polymer (A4) was obtained.

(Synthesis Example 5) Synthesis of Polymer (A5) In the same manner as in Synthesis Example 1, an oil layer mixture was prepared.
Next, 349 g of an 80% by mass aqueous solution of 2- (acryloyloxy) ethyltrimethylammonium chloride (DAA), 68 g of acrylamide (AAM), 0.065 g of N, N′-methylenebisacrylamide as a crosslinking agent, and 2,2 as a polymerization initiator A mixed aqueous solution of 0.26 g of '-azobis (2-methylpropionamidine) dihydrochloride and 222 g of pure water was added to the oil layer mixture and emulsified by stirring with a homogenizer. This was adjusted to 50 ° C. with stirring, and nitrogen gas was blown into the liquid for 30 minutes. While flowing nitrogen gas in the gas phase, polymerization was carried out at 45 to 55 ° C. for 8 hours to obtain a crosslinked polymer (A5) as a W / O emulsion liquid.

(Synthesis Example 6) Synthesis of Polymer (B1) In Synthesis Example 1, the composition of the mixed aqueous solution added to the oil layer mixture was 370 g of 70% by weight aqueous solution of diallyldimethylammonium chloride (DADMAC), 76 g of acrylamide (AAM), pure 192 g of water and 1 g of a 4% by weight toluene solution of 2,2′-azobis (2,4-dimethylvaleronitrile), except that the powder having a water content of 5% by weight or less was the same as in Synthesis Example 1. As a result, a crosslinked polymer (B1) was obtained.

(Synthesis Example 7) Synthesis of Polymer (C1) In the same manner as in Synthesis Example 1, an oil layer mixture was prepared.
Next, 363 g of an 80% by weight aqueous solution of 2- (acryloyloxy) ethyltrimethylammonium chloride (DAA), 28 g of acrylamide (AAM), 7.2 g of acrylic acid (AA), and N, N′-methylenebisacrylamide as a cross-linking agent were added in an amount of 0.3 g. A mixed aqueous solution of 04 g and 240 g of pure water was added to the oil layer mixture and emulsified by stirring with a homogenizer. This was adjusted to 50 ° C. with stirring, and nitrogen gas was blown into the liquid for 30 minutes. Thereafter, 2 g of a 4% by weight toluene solution of 2,2′-azobis (2,4-dimethylvaleronitrile) was added while flowing nitrogen gas in the gas phase, and the mixture was polymerized at 45 to 55 ° C. for 8 hours to obtain W / O type. A crosslinked polymer (C1) was obtained as an emulsion liquid.

(Synthesis Example 8) Synthesis of Polymer (Z1) In Synthesis Example 2, 0.03 g of N, N′-methylenebisacrylamide and 2,2′-azobis (2, The 4-mass toluene solution of 4-dimethylvaleronitrile) was changed to 1.5 g, and other than that was carried out in the same manner as in Synthesis Example 2 to obtain a crosslinked polymer (Z1) as a W / O emulsion liquid.

(Synthesis Example 9) Synthesis of Polymer (Z2) Of the raw material composition added to the oil layer mixture of Synthesis Example 1, 349 g of an 80% by mass aqueous solution of 2- (acryloyloxy) ethyltrimethylammonium chloride (DAA), acrylamide (AAM) ), 68 g of N, N′-methylenebisacrylamide, and 4.5 g of a 4% by weight toluene solution of 2,2′-azobis (2,4-dimethylvaleronitrile). In the same manner as in Synthesis Example 1, a crosslinked polymer (Z2) was obtained as a powder having a water content of 5% by mass or less.

[Intrinsic viscosity measurement]
About each said polymer, the intrinsic viscosity was calculated | required as follows.
(1) Five Cannon Fenceke viscometers (No. 75 manufactured by Kusano Chemical Co., Ltd.) were immersed in a neutral detergent for glassware for 1 day or longer, then thoroughly washed with deionized water and dried.
(2) 0.3 g of precisely weighed polymer was added to deionized water with stirring at 500 rpm with a magnetic stirrer, stirred for 2 hours, and then allowed to stand for 15 to 24 hours to prepare a 0.2 mass% aqueous solution. . Then, after stirring for 30 minutes at 500 rpm, the whole amount was filtered with a 3G2 glass filter.
For the polymers (A2), (A5), (C1) and (Z1), the W / O emulsion liquid was added to a large excess of acetone for precipitation purification, and this precipitate was vacuum dried. The powder was subjected to intrinsic viscosity measurement.
(3-1) For polymers (A1) to (A5), (B1), (C1), (Z1) to (Z4), (Z6) and (Z8), 50 mL of 2N sodium nitrate aqueous solution was added to 50 mL of the filtrate. In addition, after stirring with a magnetic stirrer at 500 rpm for 20 minutes, a 1N sodium nitrate aqueous solution having a polymer concentration of 0.1% by mass was obtained, and this was diluted with a 1N sodium nitrate aqueous solution to be in the range of 0.02 to 0.1% by mass. Polymer sample solutions having 5 levels of concentration were prepared. A 1N sodium nitrate aqueous solution (1N-NaNO ₃ ) was used as a blank solution.
(3-2) For the polymer (Z5), a polymer sample solution was prepared using the 0.2N or 0.1N sodium chloride aqueous solution in place of the 2N or 1N sodium nitrate aqueous solution in the above (3-1). A 0.1N sodium chloride aqueous solution (0.1N-NaCl) was used as a blank solution.
(3-3) For the polymers (Z7) and (Z9), a polymer sample solution was prepared using the 2N or 1N sodium chloride aqueous solution instead of the 2N or 1N sodium nitrate aqueous solution in the above (3-1). A 1N sodium chloride aqueous solution (1N-NaCl) was used as a blank solution.
(4) Five viscometers were vertically attached in a constant temperature water bath adjusted to a temperature of 30 ° C. (within ± 0.02 ° C.). After putting 10 mL of blank liquid into each viscometer with a whole pipette, it was allowed to stand for about 30 minutes in order to keep the temperature constant. Thereafter, the liquid was sucked up using a dropper stopper, allowed to drop naturally, and the time for passing through the marked line was measured to 1/100 second unit with a stopwatch. This measurement was repeated 5 times for each viscometer, and the average value was defined as a blank value (t ₀ ).
(5) Each 10 mL of the polymer sample solution having the five levels of concentration prepared above was put into five viscometers where the blank solution was measured, and was allowed to stand for about 30 minutes in order to keep the temperature constant. Thereafter, the same operation as the measurement of the blank solution was repeated three times, and the average value of the transit time for each concentration was taken as the measurement value (t).
(6) Relative viscosity η _rel , specific viscosity η _SP , and reduced viscosity from the blank value t ₀ and measured value t, and the concentration C [mass / volume%] (= C [g / dL]) of the polymer sample solution η _SP / C [dL / g] was determined by the following relational expression.
η _rel = t / t ₀
η _SP = (t−t ₀ ) / t ₀ = η _rel −1
From these values, the intrinsic viscosity [η] of each polymer was calculated according to the method for obtaining the intrinsic viscosity based on the Huggins equation described above.

The measurement results of intrinsic viscosity for each polymer are shown in Table 1 below.
In addition, the abbreviation in the monomer composition of Table 1 is as follows.
・ Cationic monomer (1)
DAA: 2- (acryloyloxy) ethyltrimethylammonium chloride DAM: 2- (methacryloyloxy) ethyltrimethylammonium chloride DAM (Bz): 2- (methacryloyloxy) ethyldimethylbenzylammonium chloride DAM (sulfuric acid): 2- (methacryloyloxy) ) Ethyldimethylamine sulfate / nonionic monomer AAM: Acrylamide / cationic monomer (2)
DADMAC: diallyldimethylammonium chloride anionic monomer (3)
AA: Acrylic acid NaA: Sodium acrylate

[Sludge dewatering evaluation]
The sludge dewatering agent samples using the various polymers shown in Table 1 were subjected to an evaluation test of sludge dewatering for various sludges. In addition, the polymer concentration of the aqueous solution of each polymer used in the following evaluation test was 0.2% by mass except for the polymer (Z9), and the polymer (Z9) was 0.1% by mass.

Table 2 below shows the properties of various sludges used in the evaluation test. In addition, the abbreviation of each component in the property of sludge and the measuring method (based on the sewer test method) are as follows. Further, “%” in the unit notation of each component amount in Table 2 means mass%.
SS (Suspended Solid): Suspended matter; 100 mL of sludge is centrifuged at 3000 rpm for 10 minutes to remove the supernatant, and the precipitate is poured into a weighed crucible while washing with water, and the mass after drying at 105 to 110 ° C. It is shown as a mass ratio to sludge.
VSS (Volatile suspended solids): Loss of ignition of suspended solids; After the suspended matter is weighed, the crucible containing suspended matter is ignited at a temperature within the range of 600 ± 25 ° C, weighed after standing to cool, before and after ignition The difference in mass was expressed as a mass ratio with respect to suspended matter.
TS (Total solids); evaporation residue; 100 mL of sludge was placed in a weighed crucible, and the mass after drying at 105 to 110 ° C. was shown as a mass ratio to the sludge.
VTS (Volatile Total Solids): Loss on ignition; after weighing the evaporation residue, the crucible containing the evaporation residue is ignited at a temperature within a range of 600 ± 25 ° C. The difference was expressed as a mass ratio with respect to the evaporation residue.
Fiber content: 100 mL of sludge was filtered through a 100-mesh sieve, the residue on the sieve was poured into a crucible while washing with water, and the crucible after drying at 105 to 110 ° C. was weighed. Thereafter, the mixture was ignited in a temperature range of 600 ± 25 ° C., allowed to cool and weighed, and the difference in mass before and after ignition was shown as a mass ratio with respect to the suspended matter.

Example 1
A 0.2 mass% aqueous solution of polymer (A1) and a 0.2 mass% aqueous solution of polymer (Z4) were mixed at a mass ratio of 50:50 to prepare a sludge dehydrating agent sample (polymer aqueous solution).
This sludge dewatering agent sample is added to 1200 mL of sludge 1 collected in a 300 mL beaker at a polymer addition amount of 120 mg / L (0.9 mass% / SS), and stirred at 180 rpm for 30 seconds to form a coagulated floc. It was.

(Examples 2 to 24 and Comparative Examples 1 to 24)
In Example 1, the type of sludge, the type of polymer used, and the amount added were changed as shown in Table 3 below. Otherwise, a sludge dehydrating agent sample was prepared and added to the sludge in the same manner as in Example 1. Thus, an agglomerated floc was formed.

(Example 25)
To 200 mL of sludge 5 collected in a 300 mL beaker, a 0.2 mass% aqueous solution of polymer (A1) was added at a polymer addition amount of 90 mg / L (0.4 mass% / SS), and stirred at 180 rpm for 30 seconds. A 0.1% by mass aqueous solution of polymer (Z9) (anionic polymer) was added at a polymer addition amount of 35 mg / L (0.15% by mass / SS), and further stirred at 180 rpm for 20 seconds to form an aggregated floc. I let you.

(Comparative Example 25)
In Example 25, the polymer (Z3) was used in place of the polymer (A1), and other than that, aggregated flocs were formed in the same manner as in Example 25.

The evaluation test items and the evaluation method for the sludge dewatering agent sample are as follows. These evaluation results are summarized in Tables 3 and 4 below.
<Flock diameter>
About the aggregated flocs formed in the above examples and comparative examples, about 100 floc diameters that can be observed from the top of the beaker were visually measured with a measure to obtain an approximate average size.
It can be said that the larger the floc diameter, the higher the floc-forming ability of the sludge dewatering agent and the better the dewatering effect.
<20-second filtration rate>
A Buchner funnel having an inner diameter of 80 mm and a hole diameter of about 1 mm was placed on a 200 mL measuring cylinder, and a polyvinyl chloride tube having a diameter of 50 mm was placed thereon. In this cylinder, the agglomerated sludge after measuring the floc diameter as described above was poured at once, and the filtration amount after 20 seconds from the injection was read from the scale of the graduated cylinder and measured.
It can be said that the greater the amount of filtration, the better the gravity filterability and the better the dehydration effect.
<SS leak amount>
After the measurement of the filtration amount for 20 seconds, the solid content of sludge that passed through the Buchner funnel 60 seconds after the injection was read as SS leak amount from the scale of the graduated cylinder and measured.
It can be said that the smaller the SS leak amount, the better the floc aggregation performance of the formed floc and the better the dehydration effect.
<Moisture content of cake>
After the above SS leak amount measurement, the aggregate remaining on the Buchner funnel was packed in a polyvinyl chloride column having a diameter of 30 mm and a height of 17.5 mm. The column was removed and squeezed at 0.1 MPa for 60 seconds to obtain a dehydrated cake. The mass of the dehydrated cake and the mass after the dehydrated cake was dried at 105 ° C. were measured, and the moisture content of the cake was calculated by regarding the reduced amount as the water content of the dehydrated cake.
When the moisture content of the cake is about 80 to 85% by mass, the dehydrated cake can be handled in the same manner as in the past, and a lower value is preferable from the viewpoint of drying treatment and the like.

In addition, about the comparative examples 3 and 12, aggregation floc could not be filtered and squeezed. Moreover, about Comparative Examples 11, 14, 18, 19, 21, and 22, it was not possible to squeeze the aggregated floc.

As can be seen from the results shown in Tables 3 and 4, according to the sludge dewatering agent of the present invention containing a crosslinked polymer having a predetermined intrinsic viscosity, the floc diameter is large, the filtration amount is large for 20 seconds, and the SS leak amount is small. Moreover, the moisture content of the cake could be reduced. That is, it was confirmed that the sludge dewatering agent of the present invention is excellent in the dewatering effect.
Moreover, when the sludge dehydrating agent of the present invention and other polymers other than that were used in combination, the floc diameter was increased and a tendency to exhibit good cohesiveness was observed.

Claims

The polymer contains one or more crosslinked polymers selected from the following polymers A, B and C, and the crosslinked polymer has an intrinsic viscosity at 30 ° C. in a 1.0 N sodium nitrate aqueous solution of 0.5 to 5.0 dL / Sludge dewatering agent which is g.
Polymer A: Crosslink in which the monomer composition of the polymer structural unit is 1-100 mol% of a cationic monomer represented by the following general formula (1) and 0-99 mol% of a nonionic monomer polymer

(In the formula (1), R 1 represents .R 2 and R 3 is a hydrogen atom or a methyl group are each independently an alkyl or alkoxy group having 1 to 3 carbon atoms, or .R 4 is a benzyl group , A hydrogen atom, an alkyl or alkoxy group having 1 to 3 carbon atoms, or a benzyl group, A is an oxygen atom or NH group, B is an alkylene group or alkoxylene group having 2 to 4 carbon atoms, X - is an anion).
Polymer B: Crosslink in which the monomer composition of the polymer structural unit is 1 to 100 mol% of a cationic monomer represented by the following general formula (2) and 0 to 99 mol% of a nonionic monomer polymer

(In Formula (2), R 5 and R 6 are each independently a hydrogen atom or a methyl group. X − is an anion.)
Polymer C: Anionic monomer having a monomer composition of a polymer constituent unit of 1 to 99 mol% of the cationic monomer represented by the general formula (1) and the following general formula (3) Crosslinked polymer comprising 1 to 99 mol% and nonionic monomer 0 to 98 mol%

(In the formula (3), R 7 is a hydrogen atom or CH 2 COOY. R 8 is a hydrogen atom, a methyl group or COOY. Q is SO 3 − , C 6 H 4 SO 3 − , CONHC (CH 3 ) 2 CH 2 SO 3 - or COO - is .Y is a hydrogen atom or a cation).
The sludge dewatering agent according to claim 1, which is an emulsion liquid, or a dry granulated body or powder thereof.
A sludge dewatering method in which the sludge dewatering agent according to claim 1 or 2 is added to sludge to dewater the sludge.
The sludge dewatering method according to claim 3, wherein the sludge dehydrating agent is used in combination with another polymer other than the crosslinked polymer, and the other polymer is a polymer having a cationic functional group or an anionic polymer.
In the polymer having a cationic functional group, the monomer composition of the polymer constituent unit is a cationic monomer represented by the general formula (1) and a cationic monomer represented by the general formula (2). 1 to 100 mol% of one or more cationic monomers selected from the body, 0 to 99 mol% of nonionic monomers, and an anionic monomer represented by the general formula (3) The sludge dewatering method according to claim 4, comprising 0 to 50 mol%.