TWI743324B - Sludge dewatering agent and sludge dewatering method - Google Patents

Abstract

The present invention provides a sludge dewatering agent that is excellent in dewatering effects, particularly floc-forming ability and gravity filterability even if the added amount is small, and a sludge dewatering method using the sludge dewatering agent. A sludge dewatering agent and a sludge dewatering method using the same. The sludge dewatering agent comprises at least one selected from the group consisting of polymer A, polymer B, and polymer C containing monomers represented by a specific structural formula A cross-linked polymer, and the inherent viscosity of the cross-linked polymer measured by 1.0 N sodium nitrate is 0.5 dL/g to 5.0 dL/g.

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 difficult-to-dehydrate sludge, and a sludge dewatering method using the sludge dewatering agent.

Cationic polymer flocculants are generally used for the dehydration treatment of sludge mainly composed of surplus sludge produced in food factories, chemical factories, and fecal treatment plants. However, with the recent increase in the amount of sludge produced or changes in sludge properties, it has become difficult to dewater, and there is a strong demand for enhancement of dewatering effects such as gravity filterability.

Previously, as cationic polymer flocculants added to sludge, dimethylaminoethyl (meth)acrylate or its chlorinated methyl quaternary products were mainly used, but in order to further improve the dehydration effect, in addition to In addition to the treatment performed by such a cationic polymer flocculant, for example, proposals as shown in Patent Document 1 to Patent Document 5 have also been proposed.

Patent Document 1 describes that an ionic water-soluble polymer having a charge content of 35% to 90% obtained by granulating a water-in-oil emulsion liquid through a drying step is used for the dehydration treatment of sludge. In addition, Patent Document 2 and Patent Document 3 describe the use of a combination of two cross-linkable water-soluble ionic polymers, the one with high charge content and the one with low charge content, as a sludge dewatering agent. Agent. In addition, Patent Document 4 discloses a sludge dehydrating agent obtained by a mixture of an amidine-based polymer, a cross-linked cationic polymer, and a non-cross-linked cationic polymer, and Patent Document 5 discloses an addition of inorganic A sludge treatment method in which an amphoteric polymer flocculant is added after the flocculant. [Prior Art Document] [Patent Document]

Patent Document 1: Japanese Patent Laid-Open No. 2009-280649 Patent Document 2: Japanese Patent Laid-Open No. 2005-144346 Patent Document 3: International Publication No. 2008/015769 Patent Document 4: Japanese Patent Laid-Open No. 2011-224420 Patent Document 5: Japanese Patent Laid-Open No. 63-158200

[Problem to be solved by the invention] However, in the prior art as described above, the formed floc (floc) is small, or the adjustment of the addition balance of the two reagents is complicated, etc., which may not be able to efficiently perform sludge removal. Dehydration treatment. In addition, Patent Document 3 enumerates the following problems: the cross-linked polymer is cross-linked to suppress the diffusion of molecules in water, and exists as a "density-filled" molecular form, so it is necessary for coagulation of sludge The amount of sludge dehydrating agent added increased. In this case, it is considered that in a state where the diffusion of molecules of the sludge dehydrating agent is suppressed, that is, when the inherent viscosity is low, the sludge aggregation effect is poor. However, the mechanism related to the relationship between the molecular diffusion of the polymer as a sludge dehydrating agent in water and the dehydration effect is not very clear.

Therefore, the inventors of the present invention paid attention to the relationship between the diffusion of crosslinkable polymer molecules and the effect on sludge aggregation and conducted repeated studies. As a result, it was found that the specific polymer exhibits an excellent dehydration effect with a small addition amount.

That is, an object of the present invention is to provide a sludge dewatering agent that has excellent dewatering effects, particularly floc-forming ability and gravity filterability, even if the addition amount is small, and a sludge dewatering method using the sludge dewatering agent. [Means to solve the problem]

The present invention is based on the discovery that a dehydration treatment agent containing a specific crosslinked polymer and having a specific inherent viscosity exhibits excellent floc-forming power and gravity filterability with a small addition amount.

（式（1）中，R¹ 為氫原子或甲基。R² 及R³ 分別獨立地為碳數1～3的烷基或烷氧基、或者苄基。R⁴ 為氫原子、碳數1～3的烷基或烷氧基、或者苄基。A為氧原子或NH基。B為碳數2～4的伸烷基或伸烷氧基（alkoxylene）。X^- 為陰離子） 聚合物B：聚合物構成單元的單體組成包含由下述通式（2）表示的陽離子性單體1莫耳%～100莫耳%與非離子性單體0莫耳%～99莫耳%的交聯聚合物 [化2]

（式（2）中，R⁵ 及R⁶ 分別獨立地為氫原子或甲基。X^- 為陰離子） 聚合物C：聚合物構成單元的單體組成包含由所述通式（1）表示的陽離子性單體1莫耳%～99莫耳%、由下述通式（3）表示的陰離子性單體1莫耳%～99莫耳%、及非離子性單體0莫耳%～98莫耳%的交聯聚合物 [化3]

（式（3）中，R⁷ 為氫原子或CH₂ COOY。R⁸ 為氫原子、甲基或COOY。Q為SO₃ ^- 、C₆ H₄ SO₃ ^- 、CONHC(CH₃ )₂ CH₂ SO₃ ^- 或COO^- 。Y為氫原子或陽離子） [2] 如所述[1]所述的污泥脫水劑，其為乳劑狀液體、或者其乾燥造粒體或粉體。That is, the present invention provides the following [1] to [5]. [1] A sludge dehydrating agent, comprising at least one cross-linked polymer selected from the following polymer A, polymer B, and polymer C, and the cross-linked polymer is mixed in 1.0 N sodium nitrate aqueous solution The intrinsic viscosity at 30°C is 0.5 dL/g～5.0 dL/g. Polymer A: The monomer composition of the polymer constituent unit includes a cationic monomer represented by the following general formula (1): 1 mol% to 100 mol% and nonionic monomer 0 mol% to 99 mol% % Of cross-linked polymer [Chemical 1]

(In 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 carbons, or a benzyl group. R ⁴ is a hydrogen atom, a carbon number 1-3 alkyl or alkoxy, or benzyl. A is an oxygen atom or NH group. B is an alkylene or alkoxylene with 2 to 4 carbon atoms. X ^- is an anion) polymer B: The monomer composition of the polymer constituent unit includes a cationic monomer represented by the following general formula (2): 1 mol% to 100 mol% and nonionic monomer 0 mol% to 99 mol% Cross-linked polymer [化2]

(In formula (2), R ⁵ and R ⁶ are each independently a hydrogen atom or a methyl group. X ^- is an anion) Polymer C: The monomer composition of the polymer constituent unit includes the one represented by the general formula (1) Cationic monomer 1 mol% to 99 mol%, anionic monomer represented by the following general formula (3) 1 mol% to 99 mol%, and nonionic monomer 0 mol% to 98 mol% Mole% cross-linked polymer [Chemical 3]

(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) [2] The sludge dewatering agent described in [1] is an emulsion liquid, or its dried granulated body or powder.

[3] A method for dewatering sludge, in which the sludge dewatering agent described in [1] or [2] is added to sludge, and the sludge is dewatered. [4] The sludge dewatering method described in [3], wherein the sludge dewatering agent is used in combination with another polymer other than the crosslinked polymer, and the other polymer has a cationic function -Based polymer or anionic polymer. [5] The sludge dewatering method described in [4], wherein in the polymer having a cationic functional group, the monomer composition of the polymer constituent unit includes: selected from the general formula (1) One or more cationic monomers among the cationic monomers represented and the cationic monomers represented by the general formula (2) are from 1 mol% to 100 mol%, and nonionic monomers from 0 mol% to 99 mol%, and 0 mol% to 50 mol% of the anionic monomer represented by the general formula (3). [Effects of the invention]

According to the present invention, it is possible to provide a sludge dewatering agent that is excellent in dewatering effects, particularly in floc-forming ability and gravity filterability, even if the added amount is small. In addition, it is possible to provide an efficient sludge dewatering method using the sludge dewatering agent.

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 addition, in this specification, the term “(meth)acrylic group” means “acrylic acid group” and/or “metha-acryl (methacryl)”, and “(former) The same applies to the expressions of “(meth)acryloyl” and “(meth)acryloyl”.

[Sludge Dewatering Agent] The sludge dewatering agent of the present invention contains one or more cross-linked polymers selected from the group consisting of polymer A, polymer B, and polymer C. Moreover, the inherent viscosity of the crosslinked polymer at 30°C in a 1.0 N sodium nitrate aqueous solution is 0.5 dL/g to 5.0 dL/g. Such a sludge dewatering agent exhibits excellent dewatering effects such as floc-forming ability and gravity filterability in an added amount equal to or less than that of the existing sludge dewatering agent. It is considered that the reason for obtaining the excellent dehydration effect is the mechanism such as the following (1) and (2). (1) The cross-linked polymer having the above-mentioned inherent viscosity has a structure that is highly cross-linked and the molecules are rigid and hard to be strained. Therefore, the surface of the sludge particle does not cover the entire surface of the particle by one molecule of the cross-linked polymer, but the entire surface is covered by the strong bond with a plurality of cross-linked polymer molecules. As a result, a high-density bond is formed between the sludge particles via the cross-linked polymer, and a strong floc that is also resistant to strong shear such as agitation can be formed. (2) In addition, the cross-linked polymer contains cationic charges inside the highly cross-linked structure. By applying physical force such as stirring, the enclosed cationic charges are slowly released to the outside. The successive reactions between the charge and the surface of the sludge particles tend to form coarse flocs.

(Crosslinked polymer) The crosslinked polymer used in the sludge dehydrating agent is one or more selected from the group consisting of polymer A, polymer B, and polymer C shown below. Among these, one kind may be used alone, or two or more kinds may be used in combination. Among these, from the viewpoint of obtaining a more excellent dehydration effect, it is preferable to include the polymer A. The crosslinked polymer is more preferably polymer A.

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

<Polymer A> The monomer composition of polymer A is a polymer constituent unit and contains a cationic monomer represented by the following general formula (1) (hereinafter only expressed as "cationic monomer (1)") 1 mol %～100 mol% and nonionic monomer 0 mol%～99 mol% cross-linked polymer. The method of polymerizing these monomers to form a crosslinked polymer is not particularly limited, and a crosslinking agent is used as necessary. Furthermore, the monomer composition of the polymer constituent unit mentioned in the present invention does not include the crosslinking agent.

[化4]

In the formula (1), R ¹ is a hydrogen atom or a methyl group. R ² and R ³ are each independently an alkyl group having 1 to 3 carbons, an alkoxy group, or a benzyl group. R ⁴ is a hydrogen atom, an alkyl group or alkoxy group having 1 to 3 carbon atoms, or a benzyl group. A is an oxygen atom or an NH group. B is an alkylene group or alkoxy group having 2 to 4 carbon atoms. X ^- is an anion, preferably chlorine, bromine, iodine, 1/2 · SO ₄ ^- or CH ₃ SO ₄ ^-.

As the cationic monomer (1), for example, 2-((meth)acryloyloxy)ethyltrimethylammonium chloride, 2-((meth)acryloyloxy)ethyldimethyl (Meth)acryloyloxyalkyl quaternary ammonium salt such as benzyl ammonium chloride; 2-((meth)acryloyloxy)ethyldimethylamine sulfate or hydrochloride, 3-( (Meth)acryloyloxy)propyldimethylamine hydrochloride and other (meth)acryloyloxyalkyl tertiary amine salts; 3-((meth)acryloylamino)propyl three (Meth)acrylamido alkyl quaternary ammonium salts such as methyl ammonium chloride, 3-((meth)acrylamido)propyltrimethylammonium methyl sulfate and the like. Among these, one kind may be used alone, or two or more kinds may be used in combination. Among these, the (meth)acryloyloxyalkyl quaternary ammonium salt is preferred, and in particular, in terms of easily obtaining a cross-linked polymer with excellent polymerizability and a strong structure, 2-(acryloyloxyalkyl) is preferred. (Oxy) ethyl trimethyl ammonium chloride.

The polymer A contains the cationic monomer (1) from 1 mol% to 100 mol% as a polymer constituent unit. That is, regarding polymer A, all of its constituent monomers may be cationic monomer (1), or alternatively, cationic monomer (1) 1 mol% or more and less than 100 mol% and nonionic monomer Copolymer with less than 99 mol%. However, since a polymer having a cationic monomer (1) of 100 mol% has high hygroscopicity, it is preferable that the polymer A is a copolymer from the viewpoints of the dehydration effect and workability of the sludge dehydrating agent. In the polymer constituent units of the copolymer, the ratio of the cationic monomer (1) is preferably 30 mol% to 95 mol%, more preferably 50 mol% to 90 mol%, and further preferably 55 mol%. Ear%～85 mol%.

Examples of the nonionic monomer include amides such as (meth)acrylamide and N,N-dimethyl(meth)acrylamide; and vinyl cyanide such as (meth)acrylonitrile. vinyl cyanide) compounds; (meth)acrylic acid alkyl esters such as methyl (meth)acrylate and ethyl (meth)acrylate; vinyl esters such as vinyl acetate; styrene, α-methylstyrene , Aromatic vinyl compounds such as p-methylstyrene, etc. These nonionic monomers may be used individually by 1 type, and may use 2 or more types together. Among these, in terms of easily obtaining a cross-linked polymer that is excellent in water solubility, easy to adjust the monomer composition ratio in the polymer, and has a strong structure, acrylamide is preferred.

<Polymer B> The monomer composition of polymer B is a polymer constituent unit and contains a cationic monomer represented by the following general formula (2) (hereinafter only expressed as "cationic monomer (2)") 1 mol %～100 mol% and nonionic monomer 0 mol%～99 mol% cross-linked polymer. The method of polymerizing these monomers to form a crosslinked polymer is not particularly limited, and a crosslinking agent is used as necessary.

[化5]

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

Examples of the cationic monomer (2) include diallyldimethylammonium chloride, dimethylallyldimethylammonium chloride, and the like. Among these, one kind may be used alone, or two or more kinds may be used in combination.

The polymer B contains 1 mol% to 100 mol% of the cationic monomer (2) as a polymer constituent unit. That is, regarding polymer B, all of its constituent monomers may be cationic monomers (2), or in addition, the cationic monomers may be 1 mol% or more and less than 100 mol% and nonionic monomers. Copolymer with 99 mol% or less. From the viewpoint of the dewatering effect of the sludge dewatering agent, the polymer B is preferably a copolymer. In the polymer constituent units of the copolymer, the ratio of the cationic monomer (2) is preferably 30 mol% to 95 mol%, more preferably 50 mol% to 90 mol%, and further preferably 55 mol%. Ear%～85 mol%. The nonionic monomer is the same as the polymer A.

<Polymer C> The monomer composition of polymer C as a polymer constituent unit contains the cationic monomer (1) from 1 mol% to 99 mol%, and an anionic monomer represented by the following general formula (3) A cross-linked polymer of 1 mol% to 99 mol%, and nonionic monomer 0 mol% to 98 mol%. The method for copolymerizing these monomers to form a crosslinked polymer is not particularly limited, and a crosslinking agent is used as necessary.

[化6]

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-propenamide-2-methylpropanesulfonic acid, (meth)acrylic acid, itaconic acid, and maleic acid. Acids and alkali metal salts of these. Among these, one kind may be used alone, or two or more kinds may be used in combination. Among these, acrylic acid is preferred.

The polymer C may be a copolymer of a cationic monomer (1) and an anionic monomer (3), or it may also be a copolymer in which a nonionic monomer is used as a polymer constituent unit in addition to these monomers. . In the polymer constituent units of these copolymers, the ratio of the cationic monomer (1) is preferably 30 mol% to 98 mol%, more preferably 50 mol% to 97 mol%, and still more preferably 55 mol%. Mole%～95mole%. In addition, the ratio of the anionic monomer (3) is preferably 2 mol% to 70 mol%, more preferably 3 mol% to 50 mol%, and still more preferably 5 mol% to 45 mol%. When polymer C is a copolymer of cationic monomer (1) and anionic monomer (3), the ratio of cationic monomer (1) in the polymer constituent units of the copolymer is preferably 30 Mole% to 98 mole%, more preferably 50 mole% to 97 mole%, and still more preferably 55 mole% to 95 mole%. When polymer C is a copolymer of cationic monomer (1), anionic monomer (3), and nonionic monomer, the ratio of nonionic monomer is preferably 1 mol% to 65 mol% Ear%, more preferably 5 mol% to 50 mol%, further preferably 10 mol% to 35 mol%. The preferred ratios of the cationic monomer (1), the anionic monomer (3) and the nonionic monomer range from 55 mol% to 80 mol%, 5 mol% to 15 mol%, and 10 mol%, respectively. Mole%～30mole%. The nonionic monomer is the same as the polymer A.

(Intrinsic viscosity) The inherent viscosity of the cross-linked polymer constituting the sludge dehydrating agent of the present invention at 30°C in a 1.0 N sodium nitrate aqueous solution is 0.5 dL/g to 5.0 dL/g. Intrinsic viscosity is also an indicator of molecular weight, and there is a tendency that the greater the molecular weight of the polymer, the higher the intrinsic viscosity. However, the intrinsic viscosity is also affected by the structure of the monomer as the polymer constituent unit, polymerization conditions, and the like, and therefore does not necessarily correspond to the molecular weight. In the present invention, the cross-linked polymer having a specific inherent viscosity is used.

When the intrinsic viscosity is outside the above range, the diameter of the formed flocs is difficult to increase and the gravity filterability is poor, and there is a tendency that a sufficient dehydration effect cannot be obtained. From the viewpoint of obtaining a more excellent dehydration effect, the inherent viscosity of the cross-linked polymer is preferably 0.8 dL/g to 4.9 dL/g, more preferably 1.0 dL/g to 4.5 dL/g, and still more preferably 1.2 dL /g～4.5 dL/g.

The intrinsic viscosity is represented by [η], and is set to a value calculated using the following Huggins equation. The Heggins formula: η _SP /C=[η]+k'[η] ² C In the formula, η _SP : represents the specific viscosity (=η _rel -1), k': represents the Heggins constant, C : Indicates the viscosity of the polymer solution, η _rel : indicates the relative viscosity. Prepare solutions of different concentrations of cross-linked polymer, find the specific viscosity η _SP for each concentration solution, and plot _{the relationship of η SP} /C to C, and the value of the intercept of C extrapolated to 0 is the intrinsic viscosity [ η]. The specific viscosity η _SP is obtained by a method as shown in the following examples.

[Manufacturing method of crosslinked polymer] The crosslinked polymer can be manufactured by mixing and polymerizing monomers, polymerization initiators, and, if necessary, crosslinking agents that become the constituent units of the polymer.

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

As the crosslinking agent, for example, N,N'-methylenebis(meth)acrylamide, triallylamine, ethylene glycol di(meth)acrylate, polyethylene glycol di(meth) Acrylate, 1,3-butanediol di(meth)acrylate, etc. The addition amount of the crosslinking agent is adjusted so that the inherent viscosity of the crosslinked polymer falls within the aforementioned range. Generally, it is preferably 50 ppm to 500 ppm, more preferably 80 ppm to 300 ppm, and still more preferably 100 ppm to 200 ppm with respect to the total monomer mass other than 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 viewpoints of easy handling of the obtained cross-linked polymer or solubility in sludge, etc., a manufacturing method obtained as an emulsion liquid is preferred, and an emulsion polymerization method is more preferred. The cross-linked polymer is obtained as a water-in-oil emulsion (W/O (water-in-oil) emulsion)-like liquid. Emulsification polymerization can be carried out, for example, by the following method: adding a monomer containing a polymer constituent unit that becomes a crosslinked polymer, water, and optionally a crosslinking agent, etc., to an oil layer mixture containing a surfactant and an oil solvent. The aqueous solution is stirred and mixed to emulsify, and a polymerization initiator is added thereto. By this method, a cross-linked polymer as a W/O emulsion liquid is obtained. As the oily solvent, for example, mineral oils such as kerosene and light oil, and normal paraffins, isoparaffins, naphthenic oils, etc., which are refined products of these, can be used. In addition, It is also possible to use synthetic oils, vegetable oils, animal oils or mixtures of these with the same properties as these. As the surfactant, for example, sorbitan fatty acid esters such as sorbitan monooleate and sorbitan monostearate can be preferably used; polyoxyethylene lauryl ether, pentane Nonionic surfactants such as polyoxyethylene alkyl ethers such as oxyethylene oleyl ether.

In addition, the cross-linked polymer obtained as such an emulsion liquid may be granulated or powdered by spray drying using a spray dryer or the like to prepare a dry granulated body or powder. If set to this form, the ease of handling of the sludge dewatering agent can be improved.

[Sludge Dewatering Method] The sludge dewatering method of the present invention is to add the sludge dewatering agent to sludge such as excess sludge or mixed sludge originating from a food factory, a chemical plant, a fecal treatment plant, etc. The method for dewatering sludge is described. The sludge dewatering agent of the present invention can exhibit an excellent dewatering effect even in a small amount, so the amount of sludge added can be suppressed, and the operability of the dewatering treatment can be improved or cost reduction can be achieved. For example, when the concentration of suspended matter (Suspended Solid (SS)) is about 0.4% to 4.0% by mass, the added amount of the sludge dewatering agent is preferably 20 mg/L to 1600 mg/L , More preferably 50 mg/L to 1200 mg/L, further preferably 60 mg/L to 800 mg/L.

The addition method of adding the said sludge dehydrating agent to sludge is not specifically limited, The addition method of a well-known sludge dehydrating agent can be applied. Generally speaking, the cross-linked polymer concentration in the sludge dehydrating agent is 0.01% by mass to 0.5% by mass, preferably 0.03% by mass to 0.3% by mass, and an aqueous solution or dispersion is added to the sludge. . Optionally, it can also be added in solid form such as powder.

(Combined use with other polymers) In the sludge dewatering method using the sludge dewatering agent of the present invention, the sludge dewatering agent may be used in combination with other polymers other than the cross-linked polymer. Examples of other polymers to be used in combination include polymers having cationic functional groups or anionic polymers. The polymer having a cationic functional group includes not only a cationic polymer but also an amphoteric polymer. In addition, the other polymer that can be used in combination may be a cross-linked type or a non-cross-linked type such as a linear form. However, from the viewpoint of fully exerting the dehydration effect of the sludge dehydrating agent, the linear form is preferred. By. Similar to the cross-linked polymer of the sludge dehydrating agent, these other polymers are preferably added to the sludge as an aqueous solution or dispersion with a polymer concentration of 0.01% to 0.5% by mass. More preferably, it is 0.03% by mass to 0.3% by mass. In addition, it may be added in a solid state such as a powder as the case may be.

<Polymer having a cationic functional group> As a polymer having a cationic functional group, for example, the monomer composition of the polymer constituent unit can be selected from the cationic monomer (1) and the cationic monomer (2) One or more cationic monomers (hereinafter referred to as "cationic monomer (1)·(2)") 1 mol%～100 mol%, non-ionic monomer 0 mol%～ 99 mol%, and the anionic monomer (3) 0 mol%-50 mol% polymer. The polymer may be a linear polymer, or alternatively may also be a cross-linked polymer having an inherent viscosity outside the range of the inherent viscosity of the cross-linked polymer. Regarding the polymer having a cationic functional group, all of its constituent monomers may be cationic monomers (1)·(2), or alternatively may include cationic monomers (1)·(2) 1 mo Copolymers with ear% or more and less than 100 mol%, nonionic monomers from 0 mol% to 99 mol%, and anionic monomers (3) from 0 mol% to 50 mol%.

As specific examples of the cationic monomers (1) and (2) in the polymer having a cationic functional group, the same as those exemplified for the polymer A or the polymer B, include: 2-((meth)acryloyloxy) ethyl trimethyl ammonium chloride, 2-((meth)acryloyloxy) ethyl dimethyl benzyl ammonium chloride, etc.(meth)acrylic acid Oxyalkyl quaternary ammonium salt; 2-((meth)acryloyloxy)ethyldimethylamine sulfate or hydrochloride, 3-((meth)acryloyloxy)propyldimethyl (Meth)acryloyloxyalkyl tertiary amine salt such as amine hydrochloride; 3-((meth)acryloylamino)propyl trimethylammonium chloride, 3-((methyl) Acrylic amino) propyl trimethyl ammonium methyl sulfate, etc. (meth) acrylic amino alkyl quaternary ammonium salt, diallyl dimethyl ammonium chloride, dimethacrylic two Methyl ammonium chloride and so on. Among these, one kind may be used alone, or two or more kinds may be used in combination. Among these, a (meth)acryloxyalkyl quaternary ammonium salt or a (meth)acryloxyalkyl tertiary amine salt is preferred.

As a specific example of the nonionic monomer in the polymer having a cationic functional group, the same as those exemplified for the polymer A, for example, (meth)acrylamide, N, N -Dimethyl (meth)acrylamide and other amides; (meth)acrylonitrile and other vinyl cyanide compounds; (meth)acrylic acid methyl (meth)acrylate, (meth)ethyl acrylate, etc. Base esters; vinyl esters such as vinyl acetate; aromatic vinyl compounds such as styrene, α-methylstyrene, and p-methylstyrene. Among these, one kind may be used alone, or two or more kinds may be used in combination. Among these, acrylamide is preferred.

As specific examples of the anionic monomer (3) in the polymer having a cationic functional group, the same as those exemplified for the polymer C, for example, vinyl sulfonic acid, vinyl benzene sulfonic acid Acid, 2-acrylamide-2-methylpropanesulfonic acid, (meth)acrylic acid, itaconic acid, maleic acid, and alkali metal salts of these. Among these, one kind may be used alone, or two or more kinds may be used in combination. Among these, acrylic acid is preferred.

The polymer having a cationic functional group may be mixed with the sludge dehydrating agent and added as one liquid, or may be added simultaneously with the sludge dehydrating agent separately, or added sequentially. The mass ratio of the combined use of the sludge dehydrating agent and 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 to 70 :30.

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

When the anionic polymer is used in combination with the sludge dehydrating agent, it is preferable to add the anionic polymer after adding the sludge dehydrating agent to sludge. The quality 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. [Example]

Hereinafter, the present invention will be explained based on examples, but the present invention is not limited by the following examples. [Preparation of polymer] The polymer (A1) to the polymer (A5), the polymer (B1), and the polymer (C1) used in the examples were produced by the following Synthesis Example 1 to Synthesis Example 7, respectively. In addition, the polymer (Z1) and the polymer (Z2) used in the following comparative examples were produced by the following synthesis example 8 and synthesis example 9, respectively. In addition, the polymer (Z3) to the polymer (Z9) which are commercially available products were also used in the examples and comparative examples. Furthermore, the polymer (Z7) is a polyamidine-based coagulant.

(Synthesis example 1) Synthesis of polymer (A1) A 1 L four-neck separable flask equipped with a stirrer, a cooling tube, a nitrogen inlet tube, and a thermometer was charged with 312 g of normal paraffins and pentoxyethylene oleyl. 25 g of base ether and 25 g of sorbitan monooleate were stirred and mixed to prepare an oil layer mixture. Next, 388 g of an 80% by mass aqueous solution of 2-(acryloyloxy)ethyltrimethylammonium chloride (DAA) and 28 g of acrylamide (AAM) were used as A mixed aqueous solution of 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 was stirred by a homogenizer to emulsify. It was adjusted to 50°C under stirring, and nitrogen was blown into the liquid for 30 minutes. While allowing nitrogen to flow in the gaseous phase, 2 g of 2,2'-azobis(2,4-dimethylvaleronitrile) in 4% by mass toluene solution was added, and polymerization was carried out at 45°C to 55°C for 8 hours. Thus, a cross-linked polymer as a W/O emulsion liquid was obtained. The emulsion liquid was spray-dried by a desktop spray dryer to obtain a cross-linked polymer (A1) as a powder having a moisture 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 was not performed with a spray dryer. Except for this, in the same manner as in Synthesis Example 1, a crosslinked polymer (A2) as a W/O emulsion liquid was obtained.

(Synthesis Example 3) Synthesis of Polymer (A3) In Synthesis Example 1, the composition of the raw materials added to the oil layer mixture was 80% of 2-(acryloxy)ethyltrimethylammonium chloride (DAA) The mass% aqueous solution was changed to 349 g, acrylamide (AAM) was changed to 68 g, and N,N'-methylenebisacrylamide was changed to 0.05 g, except that the same as in Synthesis Example 1 In this way, a cross-linked polymer (A3) as a powder with a moisture content of 5 mass% or less was obtained.

(Synthesis Example 4) Synthesis of Polymer (A4) In Synthesis Example 1, the addition amount of N,N'-methylenebisacrylamide was 0.035 g, and the same procedure as in Synthesis Example 1 was carried out except that A crosslinked polymer (A4) which is a powder having a moisture content of 5 mass% or less 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), and N,N'-as a crosslinking agent A mixed aqueous solution of 0.065 g of methacrylamide, 0.26 g of 2,2'-azobis(2-methylpropionamidine) dihydrochloride as a polymerization initiator, and 222 g of pure water was added to the oil layer Mix the mixture with a homogenizer to emulsify it. It was adjusted to 50°C under stirring, and nitrogen was blown into the liquid for 30 minutes. While flowing nitrogen gas in a gaseous phase, polymerization was performed at 45°C 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 changed to diallyldimethylammonium chloride (DADMAC) 370 g of 70% by mass aqueous solution, 76 g of acrylamide (AAM), 192 g of pure water, and 1 g of 4% by mass toluene solution of 2,2'-azobis(2,4-dimethylvaleronitrile), except Otherwise, in the same manner as in Synthesis Example 1, a cross-linked polymer (B1) was obtained as a powder having a moisture content of 5% by mass or less.

(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 mass aqueous solution of 2-(acryloyloxy)ethyltrimethylammonium chloride (DAA), 28 g of acrylamide (AAM), and 7.2 g of acrylic acid (AA) were used as A mixed aqueous solution of 0.04 g of N,N'-methylenebisacrylamide as a cross-linking agent and 240 g of pure water was added to the oil layer mixture, and stirred by a homogenizer to emulsify. It was adjusted to 50°C under stirring, and nitrogen was blown into the liquid for 30 minutes. After that, while flowing nitrogen gas in the gaseous phase, 2 g of a 4% by mass toluene solution of 2,2'-azobis(2,4-dimethylvaleronitrile) was added at 45°C to 55°C. It was polymerized within hours to obtain a cross-linked polymer (C1) as a W/O emulsion liquid.

(Synthesis Example 8) Synthesis of Polymer (Z1) In Synthesis Example 2, in the raw material formulation composition added to the oil layer mixture, N,N'-methylenebisacrylamide was changed to 0.03 g, and 2, Except for changing the 4% by mass toluene solution of 2'-azobis(2,4-dimethylvaleronitrile) to 1.5 g, in the same manner as in Synthesis Example 2, a W/O emulsion liquid was obtained Cross-linked polymer (Z1).

(Synthesis Example 9) The synthesis of polymer (Z2) was added to the raw material formulation composition of the oil layer mixture of Synthesis Example 1, and 80 masses of 2-(acryloyloxy)ethyltrimethylammonium chloride (DAA) were added % Aqueous solution was changed to 349 g, acrylamide (AAM) was changed to 68 g, N,N'-methylenebisacrylamide was changed to 0.05 g, and 2,2'-azobis(2, Except that the 4% by mass toluene solution of 4-dimethylvaleronitrile) was changed to 4.5 g, the crosslinked polymer (Z2) was obtained as a powder with a moisture content of 5% by mass or less in the same manner as in Synthesis Example 1. .

[Measurement of Intrinsic Viscosity] For each of the above-mentioned polymers, the intrinsic viscosity was determined as follows. (1) After immersing 5 Cannon-Fenske viscometers (No. 75 manufactured by Kusano Chemical Co., Ltd.) in a neutral detergent for glassware for more than one day, use deionized water Wash and dry thoroughly. (2) 0.3 g of a finely scaled polymer was added to deionized water with a magnetic stirrer under stirring at 500 rpm, and after stirring for 2 hours, it was allowed to stand for 15 to 24 hours to prepare a 0.2% by mass aqueous solution. Then, after stirring at 500 rpm for 30 minutes, the whole amount was filtered with a 3G2 glass filter. Furthermore, for polymer (A2), polymer (A5), polymer (C1), and polymer (Z1), the W/O type emulsion liquid is added to a large excess of acetone and purified by precipitation. The precipitate was dried in vacuum to form a powder, which was used for intrinsic viscosity measurement. (3-1) About polymer (A1) ~ polymer (A5), polymer (B1), polymer (C1), polymer (Z1) ~ polymer (Z4), polymer (Z6) and polymer (Z8), 50 mL of 2 N sodium nitrate aqueous solution was added to 50 mL of filtrate, and after stirring with a magnetic stirrer at 500 rpm for 20 minutes, a 1 N sodium nitrate aqueous solution with a polymer concentration of 0.1% by mass was obtained. This was diluted with an aqueous sodium nitrate solution to prepare a polymer sample solution with a 5-level concentration in the range of 0.02% by mass to 0.1% by mass. Furthermore, a 1 N sodium nitrate aqueous solution (1 N-NaNO ₃ ) was set as a blank solution. (3-2) Regarding the polymer (Z5), in the above (3-1), a 0.2 N or 0.1 N sodium chloride aqueous solution was used instead of a 2 N or 1 N sodium nitrate aqueous solution to prepare a polymer sample solution. Furthermore, set a 0.1 N sodium chloride aqueous solution (0.1 N-NaCl) as a blank solution. (3-3) Regarding polymer (Z7) and polymer (Z9), in the above (3-1), 2 N or 1 N sodium chloride aqueous solution is used instead of 2 N or 1 N sodium nitrate aqueous solution to prepare polymerization Sample solution. Furthermore, set a 1 N sodium chloride aqueous solution (1 N-NaCl) as a blank solution. (4) Vertically install 5 viscometers in a constant temperature water tank adjusted to a temperature of 30°C (within ±0.02°C). After putting 10 mL of the blank solution into each viscometer with a whole pipette, let it stand for about 30 minutes in order to keep the temperature constant. After that, the solution was sucked up with a pipette plug and allowed to fall naturally, and the time to pass the marking line was measured by a stopwatch to the unit of 1/100 second. For each viscometer, this measurement was repeated 5 times, and the average value was set as a blank value (t ₀ ). (5) Put 10 mL each of the polymer sample solution with the 5th grade concentration prepared above into 5 viscometers for the measurement of the blank solution, and let it stand for about 30 minutes in order to keep the temperature constant. After that, the same operation as the measurement of the blank solution was repeated three times, and the average value of the passage time for each concentration was set as the measurement value (t). (6) Based on the blank value t ₀ and the measured value t, and the concentration C [mass/volume %] (=C [g/dL]) of the polymer sample solution, the following relationship is used to obtain Relative viscosity η _rel , specific viscosity η _SP and reduced viscosity η _SP /C [dL/g]. η _rel =t/t ₀ η _SP =(tt ₀ )/t ₀ =η _rel -1 Based on these values and according to the method of obtaining the inherent viscosity based on the Herkins equation, the inherent viscosity of each polymer is calculated Viscosity [η].

The measurement results of the intrinsic viscosity of each polymer are shown in Table 1 below. In addition, the abbreviations in the monomer composition of Table 1 are as follows. · Cationic monomer (1) DAA: 2-(acryloyloxy) ethyl trimethyl ammonium chloride DAM: 2-(methacryloyloxy) ethyl trimethyl ammonium chloride (2-( methacryloyloxy)ethyltrimethylammonium chloride) DAM(Bz): 2-(methacryloyloxy)ethyldimethylbenzylammonium chloride (2-(methacryloyloxy)ethyldimethylbenzylammonium chloride) DAM (sulfuric acid): 2-(methacryloyloxy) 2-(methacryloyloxy)ethyldimethylamine sulfate (2-(methacryloyloxy)ethyldimethylamine sulfate) ·Non-ionic monomer AAM: acrylamide·cationic monomer (2) DADMAC: diallyl dimethyl chloride Ammonium and anionic monomer (3) AA: acrylic acid NaA: sodium acrylate (sodium acrylate)

[Table 1]

[Evaluation of sludge dewatering] Regarding sludge dewatering agent samples using the various polymers shown in Table 1, evaluation tests for sludge dewatering for various sludges were performed. In addition, in the polymer concentration of the aqueous solution of each polymer used in the following evaluation test, the polymer (Z9) other than the polymer (Z9) was set to 0.2% by mass, and the polymer (Z9) was set to 0.1% by mass.

The properties of various sludges used in the evaluation test are shown in Table 2 below. In addition, the abbreviations and measurement methods of each component in the properties of sludge (according to the sewer test method) are as follows. In addition, "%" stated in the unit of each component amount in Table 2 means mass%. SS (Suspended Solid): suspended matter; centrifuge 100 mL of sludge at 3000 rpm for 10 minutes and remove the supernatant. While washing the sediment with water, make it flow into the weighed crucible to compare with the sludge. The mass ratio of the sludge represents the mass after drying at 105°C to 110°C. VSS (Volatile suspended solids): Ignition loss of suspended matter; burn the crucible filled with suspended matter after weighing the suspended matter at a temperature within the range of 600±25°C, and place it Weighing is performed after cooling, and the difference in mass before and after burning is expressed as the ratio of mass relative to the suspended matter. TS (Total solids): evaporation residue; put 100 mL of sludge into a weighed crucible, and express the mass after drying at 105°C to 110°C in proportion to the mass of the sludge. VTS (Volatile Total Solids): Ignition loss; at a temperature within the range of 600±25℃, burn the crucible containing the evaporation residue after weighing the evaporation residue, and place it to cool Weighing is then carried out to express the difference in mass before and after burning in a ratio relative to the mass of the evaporation residue. Fiber composition: filter 100 mL of sludge through a 100-mesh sieve, wash the residue on the sieve with water, and flow it into the crucible, weigh the crucible after drying at 105°C to 110°C. After that, it was burned in a temperature range of 600±25° C., and it was left to cool and weighed. The mass ratio of the suspended matter was used to express the difference in mass before and after the burn.

[Table 2]

(Example 1) A 0.2% by mass aqueous solution of the polymer (A1) and a 0.2% by mass aqueous solution of the polymer (Z4) were mixed at a mass ratio of 50:50 to prepare a sludge dehydrating agent sample (aqueous polymer solution). The sludge dehydrating agent sample was added to 1 200 mL of sludge 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 Coagulate flocs.

(Example 2 to Example 24 and Comparative Example 1 to Comparative Example 24) In Example 1, the type of sludge, the type of polymer used and the addition amount were changed as shown in Table 3 below, except for this Otherwise, a sludge dehydrating agent sample was prepared in the same manner as in Example 1, and added to the sludge to form a flocculated body.

(Example 25) A 0.2% by mass aqueous solution of polymer (A1) was added to 200 mL of sludge collected in a 300 mL beaker at a polymer addition amount of 90 mg/L (0.4% by mass/SS) to After stirring 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 then stirred at 180 rpm for 20 seconds. Thereby forming a coalesced floc.

(Comparative Example 25) In Example 25, except that the polymer (Z3) was used instead of the polymer (A1), an aggregated floc was formed in the same manner as in Example 25.

The evaluation test items and evaluation methods of the sludge dehydrating agent sample are as follows. These evaluation results are collectively shown in Table 3 and Table 4 below. <Floc Diameter> For the aggregated flocs formed in the above-mentioned Examples and Comparative Examples, the diameter of about 100 flocs that can be observed from the top of the beaker was measured with a ruler (measure) and visually, and the approximate Average size. It can be said that the larger the diameter of the floc, the higher the floc-forming power of the sludge dewatering agent and the better the dewatering effect. <20 second filtration> A Buchner funnel with an inner diameter of 80 mm and a pore size of about 1 mm is set on a 200 mL graduated cylinder, and a polyvinyl chloride cylinder with a diameter of 50 mm is set above it. The agglomerated sludge after measuring the diameter of the floc as described above is quickly injected into the cylinder, and the amount of filtration 20 seconds after the injection is read and measured according to the scale of the graduated cylinder. It can be said that the larger the filtration amount, the better the gravity filterability and the better the dehydration effect. <SS leakage amount> After the 20-second filtration amount measurement, the solid content of the sludge passing through the Buchner funnel 60 seconds after the liquid injection was read and measured from the scale of the graduated cylinder as the SS leakage amount. It can be said that the smaller the SS leakage, the better the coagulation performance of the formed flocs, and the better the dehydration effect. <Moisture content of cake> After the SS leakage measurement, the aggregate remaining on the Buchner funnel was packed in a polyvinyl chloride pipe column with a diameter of 30 mm and a height of 17.5 mm. Remove the pipe string and compress it at 0.1 MPa for 60 seconds to obtain a dehydrated cake. The mass of the dehydrated cake and the mass after drying the dehydrated cake at 105° C. were measured, the loss was regarded as the moisture content of the dehydrated cake, and the water content of the mud cake was calculated. If the water content of the mud cake is about 80% to 85% by mass, the dehydrated cake can be handled in the same manner as before. From the viewpoint of drying treatment, etc., the lower value is better.

In addition, regarding Comparative Example 3 and Comparative Example 12, the filtration and compression of the aggregated floc could not be performed. In addition, with regard to Comparative Example 11, Comparative Example 14, Comparative Example 18, Comparative Example 19, Comparative Example 21, and Comparative Example 22, it was impossible to compress the aggregated floc.

[table 3]

[Table 4]

As can be seen from the results shown in Table 3 and Table 4, with the sludge dewatering agent of the present invention containing a cross-linked polymer with a predetermined inherent viscosity, the diameter of the flocs becomes larger, the filtration volume in 20 seconds increases, and the SS leakage volume In addition, the moisture content of the mud cake can be reduced. That is, it was confirmed that the sludge dehydrating agent of the present invention has an excellent dehydration effect. In addition, when the sludge dewatering agent of the present invention and other polymers other than those are used in combination, it was observed that the diameter of the flocs became larger and the tendency to exhibit good cohesiveness was observed.

without

Claims (6)

A sludge dehydrating agent, which only contains the following polymer A as a polymer, and the inherent viscosity of the polymer A at 30°C in a 1.0N sodium nitrate aqueous solution is 0.8dL/g~3.7dL/g; A: The monomer composition of the polymer constituent unit includes a cationic monomer represented by the following general formula (1): 1 mol% to 100 mol% and nonionic monomer 0 mol% to 99 mol% Cross-linked polymer

(In the general formula (1), R ¹ is a hydrogen atom or a methyl group; R ² and R ³ are each independently an alkyl group having 1 to 3 carbons or an alkoxy group, or a benzyl group; R ⁴ is a hydrogen atom, a carbon An alkyl group or alkoxy group or benzyl group having a number of 1 to 3; A is an oxygen atom or an NH group; B is an alkylene group or an alkoxy group having a carbon number of 2 to 4; X ^- is an anion). The sludge dehydrating agent described in the first item of the scope of patent application is an emulsion liquid, or its dried granulated body or powder. A method for dewatering sludge. The sludge dewatering agent described in item 1 or item 2 of the scope of patent application is added to sludge, and the sludge is dewatered. A sludge dehydrating agent comprising the following polymer C, and the inherent viscosity of the polymer C at 30°C in a 1.0N sodium nitrate aqueous solution is 0.5dL/g~5.0dL/g; polymer C: polymer The monomer composition of the constituent unit includes a cationic monomer represented by the following general formula (1) from 30 mol% to 98 mol%, and an anionic monomer represented by the following general formula (3) from 2 mol% to 70 mol%, and non-ionic monomer 0 mol%~68 mol% cross-linked polymer;

(In the general formula (1), R ¹ is a hydrogen atom or a methyl group; R ² and R ³ are each independently an alkyl group having 1 to 3 carbons or an alkoxy group, or a benzyl group; R ⁴ is a hydrogen atom, a carbon An alkyl group or alkoxy group or benzyl group with a number of 1 to 3; A is an oxygen atom or an NH group; B is an alkylene group or alkoxy group with a carbon number of 2 to 4; X ^- is an anion)

In (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). The sludge dewatering agent described in item 4 of the scope of patent application is an emulsion liquid, or its dried granules or powder. A sludge dewatering method is to add the sludge dewatering agent described in item 4 or item 5 of the scope of patent application to sludge, and dewater the sludge.