JP6612630B2 - Polymer flocculant composition, method for producing the same, and sludge dewatering method using the polymer flocculant composition - Google Patents

Description

  The present invention relates to a polymer flocculant composition, a method for producing the same, and a method for dewatering sludge using the polymer flocculant composition. Specifically, the present invention relates to a polymer flocculant composition obtained by mixing a plurality of polymer compounds having a predetermined monomer unit, a method for producing the same, and a sludge dewatering method using the polymer flocculant composition.

  Polymer flocculants are used for the purpose of coagulating, settling and separating sludge contained in domestic wastewater and industrial wastewater. As polymer flocculants, cationic polymers and amphoteric polymers are frequently used. In the treatment of sludge, the moisture content of the dewatered cake is closely related to the addition rate of the polymer flocculant. When the addition rate of the polymer flocculant is low, the water content of the dehydrated cake cannot be lowered sufficiently. In addition, even when the addition rate of the polymer flocculant is high, the water content of the dehydrated cake cannot be sufficiently reduced. That is, the conventional polymer flocculant cannot exhibit good performance even if its addition rate is too low or too high. The optimum addition rate of the conventional polymer flocculant varies depending on the properties of the wastewater. In addition, conventional polymer flocculants have a narrow range of addition rates suitable for wastewater treatment.

  Patent Document 1 discloses a sludge dewatering method in which an inorganic flocculant is added, the pH is adjusted to 5 to 8, and then an amphoteric polymer flocculant is added. However, this method may not provide a sufficient effect depending on the properties of the sludge to be treated. Sludge properties vary depending on the location of the sludge, and it is difficult to treat sludge with various properties using one type of polymer flocculant. Therefore, there is a demand for a polymer flocculant that can be used for sludge having various properties.

  In order to solve these problems, sludge dewatering methods using various polymer flocculants have been proposed (Patent Documents 2-4). However, depending on the type of sludge to be treated, a conventional polymer flocculant needs to be added in a large amount to the sludge. In addition, when a conventional polymer flocculant is used, the particle size of flocs formed is reduced and the filtration rate is lowered, so that the amount of sludge treatment per unit time cannot be increased. Therefore, in the sludge dewatering method using the conventional polymer flocculant, it is difficult to sufficiently reduce the water content of the obtained dewatered cake.

JP 63-158200 A JP-A-62-205112 JP-A-53-149292 Japanese Patent Laid-Open No. 3-18900

  The problem to be solved by the present invention is to provide an excellent polymer flocculant composition that solves the above problems and a method for producing the same. Another object of the present invention is to provide a method for dewatering sludge using the polymer flocculant composition.

  As a result of intensive studies to solve the above problems, the present inventor has achieved excellent performance by mixing two or more polymer compounds having different constitutional ratios of acrylate monomer units and methacrylate monomer units. The present inventors have found that a polymer flocculant composition having can be obtained, and have completed the present invention.

  The present invention for solving the above problems is described below.

[1] A composition comprising at least the following polymer compound A and polymer compound B,
The polymer compound A has the following chemical formula (1)

(In the chemical formula (1), R ₁ is an alkyl group having 1 to 3 carbon atoms or a benzyl group, R ₂ and R ₃ are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and X is an oxygen atom or NH. Q represents an alkylene group having 1 to 4 carbon atoms or a hydroxyalkylene group having 2 to 4 carbon atoms, and Z ⁻ represents a counter anion.)
4 mol% or more of monomer units derived from the following chemical formula (2)

(In the chemical formula (2), R ₁ is an alkyl group having 1 to 3 carbon atoms or a benzyl group, R ₂ and R ₃ are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and X is an oxygen atom or NH. Q represents an alkylene group having 1 to 4 carbon atoms or a hydroxyalkylene group having 2 to 4 carbon atoms, and Z ⁻ represents a counter anion.)
A polymer compound containing 6 mol% or more of monomer units derived from
The polymer compound B comprises a monomer unit derived from the chemical formula (1) and contains 15 mol% or more of the monomer unit, or a single unit derived from the monomer unit and the chemical formula (2). A polymer compound containing a total of 20 mol% or more of monomer units,
The content ratio of the polymer compound A with respect to the total mass of the polymer compound A and the polymer compound B is 5% by mass or more and 95% by mass or less,
The molar fraction a of the monomer unit derived from the chemical formula (1) with respect to the monomer unit derived from the chemical formula (1) and the chemical formula (2) in the polymer compound A;
A molar fraction b of the monomer unit derived from the chemical formula (1) with respect to the monomer unit derived from the chemical formula (1) and the chemical formula (2) in the polymer compound B;
Is the following formula (1)
| B−a | ≧ 0.25 (1)
A polymer flocculant composition characterized by satisfying:

The polymer flocculant composition of the above [1] comprises at least polymer compound A and polymer compound B. Content of the high molecular compound A is 5 mass% or more and 95 mass% or less with respect to 100 mass parts of total amounts of the high molecular compound A and the high molecular compound B. The polymer compound A and the polymer compound B are different from each other in monomer units constituting the polymer compound. Specifically, the polymer compound A contains 4 mol% or more of acrylate monomer units derived from the chemical formula (1) and 6 mol% or more of methacrylate monomer units derived from the chemical formula (2). The polymer compound B is required to contain an acrylate monomer unit derived from the chemical formula (1) and contains 15 mol% or more of the acrylate monomer unit, or an acrylate monomer unit derived from the chemical formula (1). A total of 20 mol% or more of the monomer unit derived from the monomer unit and the chemical formula (2) is included.
And the high molecular compound A and the high molecular compound B are the mole fraction of the acrylate monomer unit derived from the chemical formula (1) to the monomer unit derived from the chemical formula (1) and the chemical formula (2). Is different by 0.25 (25%) or more.

  The reason why the combination of the polymer compound A and the polymer compound B shows a high effect is not clear, but the inventor presumes as follows. Two types of cationic monomers with different monomer reactivity ratio values are essential, and polymer compounds copolymerized with other monomers have a special chain distribution and one type of cationic monomer. The form of the chain distribution is different from that obtained by copolymerizing the product with other monomers. By blending the polymer compound A having this specific chain distribution and the polymer compound B having a different composition ratio or chain distribution, a complementary synergistic effect is exhibited. Therefore, it exhibits better agglomeration / dehydration performance compared to a single polymer compound composed of the same monomer composition or a polymer compound composed of only one kind of cationic monomer. Can do.

  [2] The polymer flocculant composition according to [1], wherein the molar fraction a is 0.60 or less.

  [3] The polymer flocculant composition according to [1] or [2], wherein the polymer flocculant composition is an emulsion.

  [4] The polymer flocculant composition according to [1] or [2], wherein the polymer flocculant composition has a powder form.

[5] The monomer represented by the chemical formula (1) is 4 mol% or more,
6 mol% or more of the monomer represented by the chemical formula (2),
Polymerizing a monomer mixture comprising a polymer compound A,
15 mol% or more of the monomer represented by the chemical formula (1) or a total of 20 mol% or more of the monomer represented by the chemical formula (1) and the monomer represented by the chemical formula (2). Polymerizing the monomer mixture to obtain polymer compound B,
The method for producing a polymer flocculant composition according to any one of [1] to [4], wherein the polymer compound A and the polymer compound B are mixed.

  [6] A dehydration method in which the polymer flocculant composition according to any one of [1] to [4] is added to sludge and dehydrated.

  Since the polymer flocculant composition of the present invention can be firmly bonded to a wide range of sludge, it exhibits an extremely high aggregating action even on difficult-to-treat sludge that has been difficult to dewater. When this is used for sludge treatment and dehydration, the formed floc has a large particle size and high strength, and therefore has a high filtration rate. Therefore, the moisture content of the dehydrated cake obtained is also low.

Hereinafter, the present invention will be described in detail.
(1) Polymer flocculant composition The polymer flocculant composition of the present invention is a composition comprising polymer compound A and polymer compound B described later. The content rate of the high molecular compound A with respect to the total mass of the high molecular compound A and the high molecular compound B is 5 mass% or more and 95 mass% or less. The lower limit of the content ratio of the polymer compound A is preferably 10% by mass or more, and more preferably 20% by mass or more. Moreover, it is preferable that the upper limit of the content rate of the high molecular compound A is 90 mass% or less, and it is more preferable that it is 80 mass% or less. Similarly, the content rate of the high molecular compound B with respect to the total mass of the high molecular compound A and the high molecular compound B is 5 mass% or more and 95 mass% or less. The lower limit of the content ratio of the polymer compound B is preferably 10% by mass or more, and more preferably 20% by mass or more. Further, the upper limit value of the content ratio of the polymer compound B is preferably 90% by mass or less, and more preferably 80% by mass or less.

  The 0.5% salt viscosity of the polymer flocculant composition of the present invention is 5 to 200 mPa · s, more preferably 10 to 150 mPa · s, and particularly preferably 20 to 100 mPa · s. When the 0.5% salt viscosity is less than 5 mPa · s, the aggregation performance as a polymer flocculant may be insufficient, and the floc diameter may not be sufficiently increased, or the gravity filterability may be reduced. If the 0.5% salt viscosity exceeds 200 mPa · s, the moisture content of the dehydrated cake may not be sufficiently reduced.

(2) Polymer compound A
In the present invention, the polymer compound A contains 4 mol% or more of acrylate monomer units derived from the following chemical formula (1) and 6 mol% or more of methacrylate monomer units derived from the following chemical formula (2). That is, the polymer compound A contains 4 mol% or more of an acrylate monomer described below and 6 mol% or more of a methacrylate monomer described below as essential components, and includes an anionic monomer and a nonionic monomer. It is produced by polymerizing a monomer mixture having a monomer as an optional component.

In the chemical formula (1), R ₁ is an alkyl group having 1 to 3 carbon atoms or a benzyl group, R ₂ and R ₃ are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, X is an oxygen atom or NH, Q Represents an alkylene group having 1 to 4 carbon atoms or a hydroxyalkylene group having 2 to 4 carbon atoms, and Z ⁻ represents a counter anion.

  Specific examples of the acrylate monomer represented by the chemical formula (1) include dialkylaminoalkyl acrylates such as dimethylaminoethyl acrylate, diethylaminoethyl acrylate and dimethylamino-2-hydroxypropyl acrylate, and dialkyls such as dimethylaminopropyl acrylamide. Aminoalkylacrylamide hydrochlorides and sulfates are exemplified. Examples of the quaternary salt include dialkylaminoalkyl acrylate and dialkylaminoalkyl acrylamide alkyl halides such as methyl chloride, benzyl halide adducts such as benzyl chloride, and dialkyl sulfate adducts such as dimethyl sulfate. The

Among these preferred acrylate monomers, the performance as a polymer flocculant is excellent, and the quality and storage stability of the acrylate monomer are excellent. Most preferred is a grade salt (DAC).
These acrylate monomers may be used alone or in combination of two or more.

  In the present invention, the polymer compound A contains 6 mol% or more of a methacrylate monomer unit derived from the following chemical formula (2).

In the chemical formula (2), R ₁ is an alkyl group having 1 to 3 carbon atoms or a benzyl group, R ₂ and R ₃ are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, X is an oxygen atom or NH, Q Represents an alkylene group having 1 to 4 carbon atoms or a hydroxyalkylene group having 2 to 4 carbon atoms, and Z ⁻ represents a counter anion.

  Specific examples of the methacrylate monomer represented by the chemical formula (2) include dialkylaminoalkyl methacrylates such as dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, and dimethylamino-2-hydroxypropyl methacrylate, dimethylaminopropyl methacrylamide, and the like. Examples of dialkylaminoalkylmethacrylamide hydrochlorides and sulfates. Also, quaternary salts such as dialkylaminoalkyl methacrylate and dialkylaminoalkylmethacrylamide haloalkyl adducts such as methyl chloride, benzyl halide adducts such as benzyl chloride, dialkyl sulfate adducts such as dimethyl sulfate, etc. are exemplified. Is done.

Among these preferable methacrylate monomers, the performance as a polymer flocculant is particularly excellent, and since the acrylate monomer is excellent in quality and storage stability, it is a methyl chloride adduct of dimethylaminoethyl methacrylate. Most preferred is a grade salt (DMC).
These methacrylate monomers may be used alone or in combination of two or more.

  The 0.5% salt viscosity of the polymer compound A is 1 to 200 mPa · s, more preferably 10 to 150 mPa · s, and particularly preferably 25 to 100 mPa · s. The range of 25 to 100 mPa · s corresponds to the range where the weight average molecular weight Mw is about 1 million to 10 million.

(3) Polymer compound B
In the present invention, it is essential that the polymer compound B contains an acrylate monomer unit derived from the above chemical formula (1). That is, in the present invention, the polymer compound B comprises a monomer mixture having an acrylate monomer described below as an essential component and a methacrylate monomer, an anionic monomer, and a nonionic monomer as optional components. Manufactured by polymerization.

  The polymer compound B contains 15 mol% or more of the acrylate monomer unit derived from the above chemical formula (1), or the acrylate monomer unit derived from the above chemical formula (1) and the above chemical formula (2). It is a polymer compound containing a total of 20 mol% or more of derived methacrylate monomer units. The polymer compound B is a polymer compound containing 15 mol% or more of an acrylate monomer unit derived from the above chemical formula (1) and not including a methacrylate monomer unit derived from the above chemical formula (2). More preferred.

  The 0.5% salt viscosity of the polymer compound B is 1 to 200 mPa · s, more preferably 10 to 150 mPa · s, and particularly preferably 20 to 100 mPa · s.

The polymer flocculant composition of the present invention comprises:
In the polymer compound A, the acrylate monomer unit derived from the aforementioned chemical formula (1) with respect to the total amount of the acrylate monomer unit derived from the aforementioned chemical formula (1) and the methacrylate monomer unit derived from the aforementioned chemical formula (2). Mole fraction a of body units,
In the polymer compound B, the acrylate monomer unit derived from the aforementioned chemical formula (1) relative to the total amount of the acrylate monomer unit derived from the aforementioned chemical formula (1) and the methacrylate monomer unit derived from the aforementioned chemical formula (2). Mole fraction b of body units;
Is the following formula (1)
| B−a | ≧ 0.25 (1)
It is characterized by satisfying.
| B−a | is preferably 0.35 or more, and more preferably 0.50 or more.
When | b−a | is 0.25 or more, the difference in the monomer composition between the polymer compound A and the polymer compound B is large, and the effect can be exerted on a wide range of sludge.
The upper limit value of | b−a | is 0.96 or less, preferably 0.90 or less, and more preferably 0.80 or less.

  Furthermore, the molar fraction a is preferably 0.60 or less, and more preferably 0.50 or less. The molar fraction b is preferably 0.60 or more, more preferably 0.80 or more, and particularly preferably 1.0.

(4) Production method of polymer compound A In the present invention, polymer compound A essentially comprises an acrylate monomer represented by the aforementioned chemical formula (1) and a methacrylate monomer represented by the aforementioned chemical formula (2). It is produced by polymerizing a monomer mixture containing an anionic monomer and a nonionic monomer as optional components.

The content of the acrylate monomer represented by the chemical formula (1) in the monomer mixture is 4 to 94 mol%, preferably 6 to 80 mol%, and more preferably 10 to 60 mol%. Preferably, it is 12-50 mol%, and it is especially preferable.
When the content of the acrylate monomer represented by the chemical formula (1) is less than 4 mol%, the effect of adding the acrylate monomer is small and it is difficult to exert an effect on a wide range of sludge. When the content of the acrylate monomer represented by the chemical formula (1) is more than 94 mol%, the effect of adding the methacrylate monomer is small, and it is difficult to exert an effect on sludge having a wide range of properties.

The content of the methacrylate monomer represented by the above chemical formula (2) in the monomer mixture is 6 to 96 mol%, preferably 8 to 93 mol%, and particularly preferably 10 to 90 mol%. preferable.
When the content of the methacrylate monomer represented by the chemical formula (2) is less than 6 mol%, the effect of adding the methacrylate monomer is small, and it is difficult to exert an effect on a wide range of sludge. When the content of the methacrylate monomer represented by the chemical formula (2) is more than 96 mol%, the effect of adding the acrylate monomer is small and it is difficult to exert the effect on a wide range of sludge.

  Examples of the anionic monomer include (meth) acrylic acid represented by the following chemical formula (3) and salts thereof, vinyl sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, maleic acid, and the like. Mention may be made of salts. Among these anionic monomers, it is excellent in copolymerizability with cationic monomers, easily increases the molecular weight required as a polymer flocculant, and has excellent performance as a polymer flocculant. (Meth) acrylic acid represented by the following chemical formula (3) and salts thereof are preferred. As the salts, ammonium salts and alkali metal salts such as sodium salts and potassium salts are preferable.

CH ₂ = CR ₁ -CO-OM (3)

However, R < ₁ > in the said Chemical formula (3) is a hydrogen atom or a methyl group, M represents a hydrogen atom, an ammonium group, or an alkali metal atom.

Among these (meth) acrylic acids and their salts, acrylic acid (AA) and its ammonium salt are most preferred because of their particularly excellent performance as a polymer flocculant.
These anionic monomers may be used alone or in combination of two or more.

  The amount of the anionic monomer in the monomer mixture is preferably 0 to 50 mol%, more preferably 1 to 40 mol%, and more preferably 1 to 30 mol%. That is, the polymer compound A preferably contains an anionic monomer unit at 0 to 50 mol%, more preferably 1 to 40 mol%, and particularly preferably 1 to 30 mol%.

  Nonionic monomers include (meth) acrylamide compounds represented by the following chemical formula (4), methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) Examples include alkyl (meth) acrylates such as hydroxyethyl acrylate, styrene, acrylonitrile, and vinyl acetate. Among these nonionic monomers, it is excellent in copolymerizability with cationic monomers, easily increases in molecular weight required as a polymer flocculant, and has excellent performance as a polymer flocculant. A (meth) acrylamide compound represented by the following chemical formula (4) is preferred.

CH ₂ = CR ₁ —CO—NR ₂ R ₃ (4)

However, R < ₁ > in the said Chemical formula (4) is a hydrogen atom or a methyl group, R < ₂ > and R < ₃ > represents a hydrogen atom or a C1-C8 alkyl group each independently.

Among these (meth) acrylamide compounds, acrylamide (AM) is most preferable because it is water-soluble and has particularly excellent performance as a polymer flocculant.
These nonionic monomers may be used alone or in combination of two or more.

  The blending amount of the nonionic monomer in the monomer mixture is preferably 0 to 90 mol%, more preferably 5 to 90 mol%, and more preferably 10 to 90 mol%. That is, the polymer compound A preferably contains nonionic monomer units at 0 to 90 mol%, more preferably 5 to 90 mol%, and particularly preferably 10 to 90 mol%.

The monomer mixture may contain a crosslinkable monomer as long as the water solubility of the resulting polymer compound is not impaired.
As the crosslinkable monomer, a (meth) acrylate-based crosslinkable monomer having two or more (meth) acryloyl groups represented by the following chemical formula (5) in one molecule (hereinafter simply referred to as “crosslinkable monomer”). May be abbreviated as “mer” or “crosslinking agent”).

CH ₂ = CR ₁ —CO— (5)

However, R < ₁ > in the said Chemical formula (5) is a hydrogen atom or a methyl group, and -CO- represents a carbonyl group.
The number of (meth) acryloyl groups in one molecule of the crosslinkable monomer is 2 or more. Those having 2 to 5 are preferred, and those having 2 to 3 are more preferred. Even if the number of (meth) acryloyl groups in one molecule exceeds 5, the effect of improving the performance as a polymer flocculant corresponding to the number of (meth) acryloyl groups may not be obtained.

  Such crosslinkable monomers include methylene bisacrylamide (MBA), ethylene or polyethylene di (meth) acrylate, polypropylene di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth). Examples include acrylate, tetramethylol methane tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, alkylene bis (meth) acrylamide, mono and polyalkylene glycol di (meth) acrylate, and polymethylolalkane poly (meth) acrylate. Is done. These may be used alone or in combination of two or more.

  When a crosslinkable monomer is included in the monomer mixture, the blending amount is preferably 0.0001 to 0.01 mol%, more preferably 0.0002 to 0.008 mol%, It is particularly preferably 0.0005 to 0.007 mol%. When the addition amount of the crosslinkable monomer is 0.0001 to 0.01 mol%, since the interaction between the crosslinkable water-soluble polymers is weak, the viscosity is low and the handling is excellent. Moreover, since the viscosity is low, the reaction with the sludge proceeds promptly and a strong floc can be formed. Moreover, when the addition amount of the crosslinkable monomer exceeds 0.01 mol%, the crosslinking reaction may proceed excessively. This increases the insoluble amount particularly in the case of aqueous solution polymerization, and as a polymer flocculant. Since the amount of the active ingredient that acts effectively is reduced, the aggregation effect cannot be sufficiently exhibited. Moreover, in the case of an emulsion, the addition amount required for a process increases and process cost increases.

  The monomer mixture may contain other copolymerizable components as long as the performance of the resulting polymer compound is not impaired.

(5) Method for Producing Polymer Compound B In the present invention, polymer compound B comprises an acrylate monomer represented by the aforementioned chemical formula (1) as an essential component, and a methacrylate monomer represented by the aforementioned chemical formula (2). It is produced by polymerizing a monomer mixture containing an anionic monomer and a nonionic monomer as optional components.

The content of the acrylate monomer represented by the chemical formula (1) in the monomer mixture is 15 to 100 mol%, and preferably 20 to 100 mol%.
When the content of the acrylate monomer represented by the chemical formula (1) is less than 15 mol%, the effect of adding the acrylate monomer is small, and it is difficult to exert an effect on a wide range of sludge.

The content of the methacrylate monomer represented by the above chemical formula (2) in the monomer mixture is 0 to 85 mol%, and it is particularly preferable that no methacrylate monomer is contained.
When the content of the methacrylate monomer represented by the chemical formula (2) is more than 85 mol%, the effect of adding the acrylate monomer is small and it is difficult to exert the effect on a wide range of sludge.

  The kind of anionic monomer is as described above.

  The compounding quantity of the anionic monomer in a monomer mixture is 0-50 mol%, and it is preferable that an anionic monomer is not included. That is, it is preferable that the high molecular compound B contains an anionic monomer unit by 0-50 mol%, and does not contain an anionic monomer unit.

  The kind of nonionic monomer is as above-mentioned.

  The compounding quantity of the nonionic monomer in a monomer mixture is 0-85 mol%, and it is preferable not to contain a nonionic monomer. That is, it is preferable that the high molecular compound B contains a nonionic monomer unit in 0-85 mol%, and does not contain a nonionic monomer unit.

  In the monomer mixture, like the polymer compound A, a crosslinkable monomer and other copolymerizable components may be contained.

(6) Polymerization method of polymer compound A and polymer compound B The polymerization method for obtaining polymer compound A and polymer compound B is not particularly limited except that it is radical polymerization, but is applied to the present invention. Specific examples of possible radical polymerization include aqueous solution polymerization, suspension polymerization, and emulsion polymerization. Among these, aqueous solution polymerization and emulsion polymerization are preferable because they are simple in operation and easy to handle raw materials and products, and are advantageous in terms of production cost in industrial production. Moreover, you may volatilize a water layer and an oil layer by emulsion polymerization, and you may make it powder.

(6-1) Aqueous Polymerization Aqueous polymerization is a method in which an aqueous solution of the monomer mixture is polymerized in the presence of a radical polymerization initiator. In the case of aqueous solution polymerization, the concentration of the monomer mixture is preferably 25 to 85 mass%, particularly preferably 30 to 65 mass%. It is preferable to adjust the pH of the aqueous solution of the monomer mixture to 2-5.

  The radical polymerization initiator used in the polymerization reaction is not particularly limited. In the case of aqueous solution polymerization, persulfates such as potassium persulfate and ammonium persulfate, organic peroxides such as t-butyl hydroperoxide, azo initiators such as azobisisobutyronitrile, redox initiators and light A polymerization initiator or the like can be used as appropriate. These radical polymerization initiators may be used alone or in combination of two or more.

  The polymerization initiation temperature is usually preferably 0 to 35 ° C. The polymerization time is usually preferably from 0.1 to 3 hours. In addition, the polymerization reaction is preferably performed in an inert atmosphere in which oxygen is not present. These polymerization conditions are known. After completion of the polymerization reaction, post-treatment such as heat treatment, drying, and pulverization is appropriately performed as necessary. A known method can be applied to these post-treatments.

  Among the production methods based on the aqueous solution polymerization, light irradiation polymerization is particularly preferable because the obtained polymer compound has few variations in physical properties and quality, can be stably produced, and can be easily adjusted. As a specific example of the light irradiation polymerization, there is exemplified a method in which polymerization is carried out by irradiating an aqueous solution of the monomer mixture with light in the presence of a photopolymerization initiator and a chain transfer agent.

The photopolymerization initiator used for light irradiation polymerization is not particularly limited. Examples of preferred photopolymerization initiators include acetophenone photopolymerization initiators and azo initiators. Among them, a water-soluble azo initiator is particularly preferable because the solubility of the monomer mixture in an aqueous solution is high and the high molecular weight necessary as a polymer flocculant is easy.
Specific examples of the water-soluble azo initiator include 2,2′-azobis (2-methylpropionamidine) dihydrochloride, 4,4′-azobis (4-cyanovaleric acid) and the like.
These photopolymerization initiators may be used alone or in combination of two or more.

  The addition amount of the photopolymerization initiator is not particularly limited. What is necessary is just to adjust suitably according to the kind of photoinitiator, monomer composition, and content of a residual monomer. In the case of a water-soluble azo initiator, usually, 100 to 3000 ppm is preferable on a mass basis with respect to the total mass of each monomer in the monomer mixture.

A chain transfer agent may be used for the purpose of adjusting the molecular weight. The type is not particularly limited. Chain transfer agents that can be used in the present invention include alcohols such as methanol, isopropyl alcohol, ethylene glycol and propylene glycol, amines such as methylamine and dimethylamine, thiols such as methanethiol and ethanethiol, and methallylsulfone. Examples include thiol compounds such as acid mercaptoethanol and mercaptopropionic acid, reducing inorganic salts such as sodium sulfite, sodium bisulfite and sodium hypophosphite, and organic sulfonic acid compounds such as methallylsulfonic acid. . Among these, sodium bisulfite is preferable because the solubility of the monomer mixture in the aqueous solution is high, the effect is high even with a small addition amount, and the molecular weight of the crosslinked water-soluble polymer can be easily adjusted.
These chain transfer agents may be used alone or in combination of two or more.

  The addition amount of the chain transfer agent is not particularly limited. In the case of sodium hydrogen sulfite, usually 5 to 500 ppm is preferable, 10 to 300 ppm is more preferable, and 15 to 200 ppm is most preferable with respect to the total mass of each monomer in the monomer mixture. If the amount of sodium bisulfite added is less than 5 ppm, the generation of insoluble matter may not be suppressed. In that case, the amount of the active ingredient that effectively acts as a polymer flocculant is reduced. Moreover, it may cause a trouble that blocks a pump that feeds a solution obtained by dissolving a polymer flocculant in water. If the amount of sodium bisulfite added exceeds 500 ppm, the molecular weight of the polymer may be too low. In that case, the cohesive force with respect to the sludge as a polymer flocculant falls, and a floc diameter does not become large. Moreover, the filtration rate may fall, or the fine solid substance in sludge may fall out into a filtrate, and the transparency of a filtrate may deteriorate.

Light irradiation conditions such as the wavelength of light used for light irradiation polymerization, irradiation intensity, and irradiation time are not particularly limited. What is necessary is just to adjust suitably according to the kind and addition amount of a photoinitiator to be used, and the physical property and performance of a polymer. When the water-soluble azo initiator is used as the photopolymerization initiator, light having a wavelength of around 365 nm is preferable, and the irradiation intensity is preferably 0.1 to 10.0 mW / cm ² measured by a UV illuminometer for 365 nm. The irradiation time is usually preferably from 0.1 to 3 hours.

(6-2) Emulsion polymerization Emulsion polymerization consists of an aqueous phase containing a predetermined monomer, radical initiator, chain transfer agent, etc., an oily substance composed of immiscible hydrocarbons, and a water-in-oil emulsion. In this method, a water-in-oil emulsion is formed using an effective amount of a surfactant to be formed, and the monomer is polymerized in the droplets of the emulsion.

  Examples of oily substances include paraffins, various mineral oils, hydrocarbon oils having characteristics equivalent to paraffins and various mineral oils, and mixtures thereof. The content of the oily substance is in the range of 15 to 50% by mass, preferably 20 to 40% by mass, based on the total amount of the water-in-oil emulsion.

  The surfactant preferably has an HLB of 3-11. Examples of such surfactants include nonionic surfactants such as sorbitan monooleate and sorbitan monostearate. The addition amount of these surfactants is preferably 0.3 to 10% by mass, and more preferably 0.5 to 5% by mass with respect to the total amount of the water-in-oil emulsion.

  The polymerization conditions for carrying out the emulsion polymerization are appropriately set according to the monomers and initiators used and the physical properties of the polymer. The polymerization temperature is preferably 5 to 90 ° C. The polymerization concentration of the monomer is preferably 20 to 60% by mass, and more preferably 20 to 50% by mass. The polymerization time is preferably 1 to 10 hours, more preferably 2 to 6 hours. The polymerization reaction is preferably performed in an inert atmosphere without oxygen.

  The average particle diameter when emulsion polymerization is performed is preferably 0.03 to 10 μm, more preferably 0.1 to 5 μm, and still more preferably 0.5 to 3 μm. The average particle diameter refers to a volume average value measured by a laser diffraction method.

  After completion of the polymerization reaction, post-treatment such as heat treatment, drying, and pulverization is appropriately performed as necessary. A known method can be applied to these post-treatments.

  In the polymer flocculant composition of the present invention, the polymer compound A and the polymer compound B may be mixed in a powder state, or may be mixed after forming an aqueous solution.

  The polymer flocculant composition of the present invention may contain a polymer component other than the polymer compound A and the polymer compound B. Further, if necessary, a pH adjusting agent such as sulfamic acid, malic acid, adipic acid, citric acid and the like; a dissolution aid such as sodium chloride, sodium sulfate, ammonium sulfate, sodium nitrate, calcium chloride and the like may be included.

(7) Sludge dewatering method In the sludge dewatering method using the polymer flocculant composition of the present invention, in addition to sludge generated in sewage treatment, human waste treatment and domestic wastewater treatment, food factories, meat processing and chemical factories, etc. Various types of sludge such as sludge generated in various industrial wastewater treatments, live urine generated in relation to livestock such as pig farms, sludge generated in the wastewater treatment, sludge generated in pulp or paper industry, etc. are targeted for treatment. There is no restriction | limiting also in the kind of sludge, and all are sludge sludge, excess sludge, and these mixed sludge, concentrated sludge, digested sludge processed by anaerobic microorganisms, etc.

  The sludge dewatering method of the present invention is characterized in that the polymer flocculant composition of the present invention is added to the above various wastewaters for dehydration. As a specific example of the dehydration method, the polymer flocculant composition of the present invention is added to various wastewaters, and the suspension in sludge and the polymer flocculant composition are mixed by stirring and / or mixing by a known method. Acts to form a sludge floc. The formed sludge floc is mechanically dehydrated by a known means to separate into treated water and dehydrated cake.

  For the purpose of deodorization, dephosphorization, denitrification, etc., it is preferable that the sludge has a pH of less than 5.

  The wastewater treatment method of the present invention can sufficiently dewater sludge without adding an inorganic flocculant.

  Although it does not restrict | limit especially as a dehydration apparatus, A screw press type dehydrator, a belt press type dehydrator, a filter press type dehydrator, a screw decanter, a multiple disk dehydrator, a rotary press filter etc. are illustrated.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. The measuring method of various physical properties is as follows. Items not described below were measured according to “JIS K0102 Factory Wastewater Test Method”. The temperature condition for measuring various physical properties is 25 ° C. unless otherwise specified.

[0.5% salt viscosity]
A sample solution was prepared by adding 20.8 g of sodium chloride and 0.50% by mass of the sample (polymer) to 500 mL of pure water and dissolving sufficiently. The liquid temperature was adjusted to 25 ± 1 ° C, and the value after rotating at 30 rpm for 3 minutes was read using a TV-10M type B type viscometer manufactured by Toki Sangyo Co., Ltd. with an M1 rotor. Viscosity. When the viscosity exceeded the measurement upper limit of the M1 rotor, the M2 rotor was used.

[Flock diameter]
It was measured visually.

[Filtration speed]
Aggregated sludge was poured into a stainless steel sieve having an inner diameter of 75 mm, a depth of 100 mm, and an opening of 80 mesh, and gravity filtered. At this time, set the funnel so that the filtrate enters the 200 mL measuring cylinder, measure the volume of the filtrate after elapse of 5 seconds, 10 seconds, 20 seconds, and 30 seconds after the sludge is charged. Gravity filtration Sex was evaluated. Among these, the volume of the filtrate after 10 seconds was defined as the amount of liquid after 10 seconds (mL).

[Cake moisture content]
Take out all the sludge hydrate cake remaining on the stainless steel sieve after measuring the filtration speed, sandwich it between the belt press filter cloth (made of polyester, Saya Aya), and use a desktop test belt press machine at 170 kPa for 3 minutes. The dehydrated cake was obtained by pressing. A portion of the center is sampled from the dehydrated cake obtained, weighed in an aluminum pan, dried for 16 hours in a hot air dryer at 105 ° C., and then measured for the weight after drying. The water content was determined from the mass ratio of

<Production Example 1>
To a stainless steel reaction vessel, 78% by mass dimethylaminoethyl methacrylate methyl chloride aqueous solution (hereinafter abbreviated as “DMC”) and 50% by mass acrylamide aqueous solution (hereinafter abbreviated as “AM”) are added, and distilled water is further added. The total mass was 1.0 kg and mixed uniformly. Each monomer had the blending ratio shown in Table 1, and the total concentration of all monomers was 40% by mass. The solution was adjusted to pH = 4, and the solution temperature was adjusted to 5 ° C. while nitrogen gas was blown into the solution for 60 minutes. Then, 2,2′-azobis (2-methylpropionamidine) dihydrochloride (hereinafter abbreviated as “V-50”) and NaHSO ₃ in terms of solid content with respect to the total mass of each monomer, They were added to 1500 ppm and 20 ppm, respectively. Next, polymerization was performed by irradiating the solution with light from above the reaction vessel to obtain a hydrogel polymer. A 13 W black light was used for light irradiation. The irradiation intensity is 0.4 mW / cm ² and the irradiation time is 60 minutes. The obtained hydrogel polymer was taken out of the container and chopped. This was dried at a temperature of 80 ° C. for 5 hours and then pulverized to obtain a powdery polymer. The 0.5% salt viscosity of this polymer was measured. The results are shown in Table 1.

<Production Examples 2 to 16>
A polymer was obtained in the same manner as in Production Example 1 except that the monomer composition was changed as shown in Table 1 or Table 2. The 0.5% salt viscosity of these polymers was measured. The results are shown in Table 1 or Table 2.

[Wastewater treatment test 1]
(Examples 1-2, Comparative Examples 1-4)
Polymer compound A and polymer compound B were mixed in the proportions shown in Table 3.
Agglomeration and dewatering performance was evaluated using paper sludge collected from a paper mill. The sludge used was pH = 6.60, total evaporation residue (TS) = 30,200 (mg / L), loss on ignition (VTS) = 51.0 (% TS), suspended matter (SS) = 14 800 (mg / L). 200 mL of this sludge was put into a 300 mL beaker, and each polymer flocculant composition was added. The addition rate (as the solid content of the flocculant) is shown in Table 3. The sludge was stirred at 200 rpm for 30 seconds using a jar tester to form a floc, and the filtration rate for 10 seconds was measured. Sludge on the filter cloth was collected and squeezed at 170 kPa for 3.0 minutes using a test belt press to obtain a dehydrated cake, and the moisture content of the cake was measured. These results are shown in Table 3.

  Since the polymer flocculant composition of Examples 1 and 2 had a predetermined monomer unit, it showed good performance. On the other hand, Comparative Examples 1 and 3 do not contain the polymer compound B. In particular, although the polymer flocculant used in Comparative Example 3 has the same monomer composition as the polymer flocculant used in Example 1, the polymer compound A and the polymer compound B are blended. It is not a polymer flocculant obtained in this way. In Comparative Example 2, the polymer compound A does not contain a monomer unit derived from DAC. In Comparative Example 4, the polymer compound A is outside the range specified in the present invention. In any of the comparative examples, the filtration rate was insufficient and the moisture content of the cake was high.

[Wastewater treatment test 2]
(Examples 3-4, Comparative Examples 5-9)
Polymer compound A and polymer compound B were mixed at the ratio shown in Table 4.
Aggregation and dewatering performance were evaluated using digested sludge collected from a sewage treatment plant. The sludge used was pH = 7.46, total evaporation residue (TS) = 16,800 (mg / L), loss on ignition (VTS) = 73.8 (% TS), suspended matter (SS) = 14 , 600 (mg / L), m-alkalinity = 2,250 (CaCO ₃ mg / L). 200 mL of this sludge was put into a 300 mL beaker, and each polymer flocculant composition was added. The addition rate (as the solid content of the flocculant) is shown in Table 4. The sludge was stirred at 200 rpm for 30 seconds using a jar tester to form a floc, and the filtration rate for 10 seconds was measured. The sludge on the filter cloth was collected and squeezed at 170 kPa for 3.0 minutes using a test belt press to obtain a dehydrated cake, and the moisture content of the cake was measured. These results are shown in Table 4.

  Since the polymer flocculant compositions of Examples 3 and 4 have predetermined monomer units, they showed good performance. On the other hand, Comparative Examples 5 and 9 do not contain the polymer compound B. In particular, although the polymer flocculant used in Comparative Example 9 has the same monomer composition as the polymer flocculant used in Example 3, the polymer compound A and polymer compound B are blended. It is not a polymer flocculant obtained in this way. In Comparative Examples 6 and 8, the difference between the molar fraction b and the molar fraction a is less than 0.25. In Comparative Example 7, the polymer compound A does not contain a monomer unit derived from DMC, and the polymer compound B does not contain a monomer unit derived from DAC. In any of the comparative examples, the filtration rate was insufficient or the moisture content of the cake was high.

<Production Example 17>
Into a 1000 ml four-necked separable flask was added 203.6 g of DMC, isopropyl alcohol (2.0% by mass with respect to the monomer) as a chain transfer agent, and distilled water, and the pH was adjusted to 4 with concentrated sulfuric acid. . Thereafter, 20 g of an aqueous solution containing 0.04 g of V-50 was added, and distilled water was added so that the total amount was 400 g to prepare a monomer aqueous solution. Furthermore, this monomer aqueous solution was added to 155 g of paraffin oil in which 10.0 g of nonionic surfactant of HLB 8.0 was dissolved, and emulsified by stirring at high speed for about 1 minute using a homogenizer. Thereafter, a nitrogen gas blowing tube, a reflux condenser, and a thermometer were attached to the flask, and the stirrer was replaced with a normal stirrer for chemical reaction, and nitrogen gas was deaerated through the emulsion for 30 minutes while stirring. Then, it heated up to 50 degreeC and superposition | polymerization was performed in nitrogen gas atmosphere. After completion of the polymerization, 17.2 g of a nonionic surfactant having an HLB of 13.0 was added to obtain an emulsion type polymer compound. The 0.5% salt viscosity of this polymer was measured. The results are shown in Table 5.

<Production Examples 18-23>
A polymer was obtained in the same manner as in Production Example 17 except that the monomer composition was changed as shown in Table 5. The 0.5% salt viscosity of these polymers was measured. The results are shown in Table 5.

[Wastewater treatment test 3]
(Examples 5-8, Comparative Examples 10-14)
Polymer compound A and polymer compound B were mixed in the proportions shown in Table 6.
Aggregation and dehydration performance were evaluated using livestock sludge collected from pig farms. The sludge used was pH = 7.59, total evaporation residue (TS) = 13,200 (mg / L), loss on ignition (VTS) = 52.7 (% TS), suspended matter (SS) = 10 800 (mg / L). 200 mL of this sludge was put into a 300 mL beaker, and each polymer flocculant composition was added. The addition rate (as the solid content of the flocculant) is shown in Table 6. The sludge was stirred at 200 rpm for 30 seconds using a jar tester to form a floc, and the filtration rate for 10 seconds was measured. Sludge on the filter cloth was collected and squeezed at 170 kPa for 3.0 minutes using a test belt press to obtain a dehydrated cake, and the moisture content of the cake was measured. These results are shown in Table 6.

Since the polymer flocculant compositions of Examples 5 to 8 had predetermined monomer units, they showed good performance. On the other hand, Comparative Examples 10 and 14 do not contain the polymer compound B. In particular, although the polymer flocculant used in Comparative Example 14 has almost the same monomer composition as the polymer flocculant used in Example 5, the polymer compound A and polymer compound B It is not a polymer flocculant obtained by blending. In Comparative Example 11, the difference between the molar fraction b and the molar fraction a is less than 0.25. In Comparative Example 12, the polymer compound B does not contain a monomer unit derived from DAC. In Comparative Example 13, the polymer compound A does not contain a monomer unit derived from DMC. In any of the comparative examples, the filtration rate was insufficient and the moisture content of the cake was high.

Claims (6)

A composition comprising at least the following polymer compound A and polymer compound B,
The polymer compound A has the following chemical formula (1)

(In the chemical formula (1), R ₁ is an alkyl group having 1 to 3 carbon atoms or a benzyl group, R ₂ and R ₃ are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and X is an oxygen atom or NH. Q represents an alkylene group having 1 to 4 carbon atoms or a hydroxyalkylene group having 2 to 4 carbon atoms, and Z ⁻ represents a counter anion.)
4 mol% or more of monomer units derived from the following chemical formula (2)

(In the chemical formula (2), R ₁ is an alkyl group having 1 to 3 carbon atoms or a benzyl group, R ₂ and R ₃ are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and X is an oxygen atom or NH. Q represents an alkylene group having 1 to 4 carbon atoms or a hydroxyalkylene group having 2 to 4 carbon atoms, and Z ⁻ represents a counter anion.)
6mol% more viewing contains a monomer unit derived from,
And the rest
The following chemical formula (3)
CH ₂ = CR ₁ -CO-OM (3)
(However, R ₁ in chemical formula (3) is a hydrogen atom or a methyl group, and M represents a hydrogen atom, an ammonium group, or an alkali metal atom.)
(Meth) acrylic acid represented by and salts thereof, and / or
The following chemical formula (4)
CH ₂ = CR ₁ —CO—NR ₂ R ₃ (4)
(However, R ₁ in chemical formula (4) is a hydrogen atom or a methyl group, and R ₂ and R ₃ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.)
Is a polymer compound composed of a (meth) acrylamide compound represented by :
The polymer compound B comprises a monomer unit derived from the chemical formula (1) and contains 15 mol% or more of the monomer unit, or a single unit derived from the monomer unit and the chemical formula (2). 20mol% or more viewing including the mer units in total,
And the rest
(Meth) acrylic acid represented by the chemical formula (3) and salts thereof, and / or a polymer compound composed of a (meth) acrylamide compound represented by the chemical formula (4) ,
The content ratio of the polymer compound A with respect to the total mass of the polymer compound A and the polymer compound B is 5% by mass or more and 95% by mass or less,
The molar fraction a of the monomer unit derived from the chemical formula (1) with respect to the monomer unit derived from the chemical formula (1) and the chemical formula (2) in the polymer compound A;
A molar fraction b of the monomer unit derived from the chemical formula (1) with respect to the monomer unit derived from the chemical formula (1) and the chemical formula (2) in the polymer compound B;
Is the following formula (1)
| B−a | ≧ 0.50 ... Number (1)
A polymer flocculant composition characterized by satisfying:   The polymer flocculant composition according to claim 1, wherein the molar fraction a is 0.60 or less.   The polymer flocculant composition according to claim 1 or 2, wherein the polymer flocculant composition is an emulsion.   The polymer flocculant composition according to claim 1 or 2, wherein the polymer flocculant composition has a powder form. 4 mol% or more of the monomer represented by the chemical formula (1),
6 mol% or more of the monomer represented by the chemical formula (2),
(Meth) acrylic acid represented by the chemical formula (3) and salts thereof, and / or a (meth) acrylamide compound represented by the chemical formula (4),
Polymerizing a monomer mixture comprising a polymer compound A,
Formula (1) with a monomer represented 15 mol% or more, or, said formula (1) 20 mol% or more in total of a monomer represented by the monomer and the chemical formula (2) indicated by a,
(Meth) acrylic acid represented by the chemical formula (3) and salts thereof, and / or a (meth) acrylamide compound represented by the chemical formula (4),
Polymerizing comprising at monomer mixture to obtain a polymer compound B with,
The method for producing a polymer flocculant composition according to any one of claims 1 to 4, wherein the polymer compound A and the polymer compound B are mixed.   A dehydration method in which the polymer flocculant composition according to any one of claims 1 to 4 is added to sludge and dehydrated.