JP5338550B2 - Sludge dewatering agent and dewatering method - Google Patents

Description

  The present invention relates to a sludge dewatering agent and a sludge dewatering method. Specifically, when a polymer containing amidine structural units is added to sludge as a sludge dewatering agent, it is generated in the treatment liquid, and it suppresses scum that causes sticking to pipes and filter cloths and causes clogging. The present invention relates to a sludge dewatering agent that does not affect the sludge dewatering performance such as the rate, and a dewatering method using this sludge dewatering agent.

  Conventionally, cationic polymer flocculants have been widely used for dewatering hydrous sludge generated during wastewater treatment or the like, depending on the properties of the sludge. Examples of such cationic polymer flocculants include polydialkylaminoalkyl (meth) acrylate salts or quaternary ammonium salts, polydialkylaminoalkyl (meth) acrylamide salts or quaternary ammonium salts, poly ( An acrylic cationic polymer such as a Mannich modified product of meth) acrylamide or a quaternary ammonium salt thereof is used. However, in recent years, the amount of sludge generated has increased due to the development of sewers, etc., and the sludge properties have deteriorated due to an increase in the amount of organic matter in the sludge, decay and the like. For this reason, the cationic polymer flocculants as described above, which are mainly used at present, are increasingly unable to perform sufficient treatment.

  For this reason, a cationic polymer flocculant containing an amidine structural unit has been proposed as an improvement of the above-mentioned cationic polymer flocculant (Patent Document 1). Cationic polymer flocculants containing such amidine units have excellent dewatering performance for sludge dewatering, but scum is generated in the dewatering treatment liquid depending on the properties of the target sludge. There is a case. Since scum causes sticking and clogging in the piping, it requires labor such as removal operation, which can prevent an efficient dehydration process, and therefore suppresses scum generated in the dehydration liquid. A method was desired. As a method for suppressing scum, after adding an amidine cationic polymer flocculant to sludge, a method of adding an anionic polymer flocculant containing a predetermined proportion of anionic group units (Patent Document 2), A method using a sludge additive comprising an amidine-based cationic polymer flocculant and an acrylic acid copolymer having special properties (Patent Document 3), an amidine-based cationic polymer flocculant and a polyoxyalkylene which is a self-emulsifying antifoaming agent Although a sludge dewatering method using a polymer (Patent Document 4) is shown, it can be said that the generation of scum is not sufficiently suppressed.

JP-A-5-192513 JP-A-9-300000 JP-A-11-277094 JP-A-9-299998

  The present invention relates to a sludge dewatering method that suppresses scum that causes damage due to adhesion to pipes and the like during the dewatering step, has good workability without incurring human and economic burdens, and a sludge dewatering agent used in this dewatering method Is to provide.

  As a result of intensive studies on the properties of the dehydration treatment liquid when the sludge was dehydrated using a cationic polymer containing an amidine structural unit, the present inventors used a cationic polymer containing an amidine structural unit. The treated water was found to be more likely to re-aggregate sludge microfloc floating in the treated water than treated water dehydrated with, for example, an aminoalkyl (meth) acrylate cationic sludge dewatering agent. The present inventors identified the microfloc re-aggregation phenomenon as a scum generation factor, and as a result of further study to solve this phenomenon, a dehydrating agent comprising a cationic polymer containing an amidine structural unit, By combining at least one polymer selected from other polymer flocculants, that is, a cationic polymer, an amphoteric copolymer, an anionic polymer, and a nonionic polymer in a predetermined ratio, the moisture content of the cake is increased. The present inventors have found that scum can be suppressed without causing deterioration.

  That is, the gist of the present invention is that a polymer (a) represented by the following general formula (1) and / or (2), a cationic polymer (b) of the following group (A), an anionic polymer ( c), a nonionic polymer (d), and an amphoteric copolymer (e) containing at least one polymer selected from the group consisting of the polymer (a) and the group (A). The present invention resides in a sludge dewatering agent having a mass ratio of 99: 1 to 91: 9 and a sludge dewatering method using the dewatering agent.

  Polymer (a) containing amidine structural unit represented by the following general formula (1) and / or (2)

（式（１）、（２）中、Ｒ¹〜Ｒ²は各々独立に水素原子またはメチル基であり、Ｘ^-は陰イオンである。）

(In formulas (1) and (2), R ^{1 and} R ² are each independently a hydrogen atom or a methyl group, and X ⁻ is an anion.)

(A) group:
A cationic polymer (b);
Polymer (b) containing a cationic monomer unit represented by the following general formula (3) as an essential constituent unit

（式（３）中、Ｒ³は水素原子又はメチル基を、Ｒ⁴は炭素数１〜４のアルキレン基、Ｒ⁵は炭素数１〜４のアルキル基、Ｒ⁶は水素原子、炭素数１〜４のアルキル基又はベンジル基、Ａは−Ｏ−又は−ＮＨ−、Ｙ^-は陰イオンを表す。）

(In the formula (3), the R ³ is a hydrogen atom or a methyl group, R ⁴ is an alkylene group having 1 to 4 carbon atoms, R ⁵ is an alkyl group having 1 to 4 carbon atoms, R ⁶ is a hydrogen atom, C 1 -C to 4 alkyl group or a benzyl group, a is -O- or -NH-, Y ^- represents an anion).

Anionic polymer (c);
Polymer (c) comprising an anionic monomer unit represented by the following general formula (4) and / or (5) as an essential constituent unit

（式（４）中、Ｒ⁷は水素又はメチル基である。ＺはＨ⁺、又はアルカリ金属イオンを表す。）

(In formula (4), R ⁷ is hydrogen or a methyl group. Z represents H ⁺ or an alkali metal ion.)

（式（５）中、ＺはＨ⁺、又はアルカリ金属イオンを表す。）

(In formula (5), Z represents H ⁺ or an alkali metal ion.)

Nonionic polymer (d);
A polymer (d) composed of a nonionic monomer unit represented by the following general formula (6),

（６）
（式（６）中、Ｒ⁸は水素又はメチル基である。Ｒ⁹、Ｒ¹⁰は、水素又は炭素数１〜４のアルキル基を表し、同じでも異なっていてもよい。）
及び

(6)
(In the formula (6), R ⁸ is .R ^9, R ¹⁰ is hydrogen or a methyl group, represents hydrogen or an alkyl group having 1 to 4 carbon atoms and may be the same or different.)
as well as

Amphoteric copolymer (e);
Polymer (e) containing the cationic monomer unit represented by the general formula (3) and the anionic monomer unit represented by the general formula (4) and / or (5) as essential constituent units -1) or a polymer (e-2) in which the polymer (e-1) further contains a nonionic monomer unit represented by the general formula (6) as a constituent unit

  If the sludge is dehydrated by the dewatering method using the sludge dewatering agent of the present invention, it is possible to suppress adhesion to pipes due to the occurrence of scum, which has been a problem in the dewatering process using the cationic dehydrating agent containing the amidine structural unit. Therefore, troubles caused by blockage of the piping can be prevented, and dehydration with good workability can be performed without putting human labor and economic burden.

Details of the present invention will be described below.
The sludge dehydrating agent of the present invention comprises a polymer (a) represented by the general formula (1) and / or (2), a cationic polymer (b) of the group (A), an anionic polymer ( It contains at least one polymer selected from c), a nonionic polymer (d), and an amphoteric copolymer (e).

The polymer (a) used in the present invention is a polymer containing an amidine ring structural unit represented by the above general formula (1) and / or (2), and is described in JP-A-5-192513. It can be produced by known methods. Specifically, N-vinylformamide and acrylonitrile are copolymerized, and the synthesized copolymer is hydrolyzed (acid-modified) under hydrochloric acid acidity to generate a primary amino group, and then the primary chain of the molecular inner chain is formed by subsequent heat treatment. An amino group and a cyano group are cyclized to form an amidine ring. The ratio (molar ratio) of N-vinylformamide and acrylonitrile to be copolymerized is usually 20:80 to 95: 5, preferably 30:70 to 90:10. The acid used for the acid modification is usually used in an amount of 0.1 to 2 times mol, preferably 0.2 to 1.5 times mol of the desired primary amino group in the copolymer. C., preferably 40 to 110.degree. The copolymer after modification is usually heated to 70 to 130 ° C., preferably 80 to 110 ° C., to form a polymer containing an amidine ring by cyclization.
In the general formulas (1) and (2), the anion X ⁻ represents a halogen ion such as Cl ⁻ or Br ⁻ or a sulfate group of 1 / 2SO ₄ ²⁻ .

  The content of the amidine ring structural unit represented by the general formula (1) and / or (2) in the polymer (a) is usually 20 mol% or more, preferably 30 mol, based on all the structural units of the polymer. %, Usually 95 mol% or less, preferably 90 mol% or less. If this content is less than 20 mol%, the effect on sludge having a neutral to weak alkaline pH may be lowered, and if it exceeds 95 mol%, no further effect can be expected. The molecular weight of the polymer (a) is preferably 100,000 to 5,000,000, more preferably 1,000,000 to 5,000,000. If it is 100,000 or less, the dehydrating power is lowered, and if it is 5 million or more, the productivity in the production of the polymer is lowered. The 0.5% salt viscosity is preferably 1 mPa · s or more and 20 mPa · s or less.

The cationic polymer (b) used in the present invention contains the cationic monomer unit represented by the general formula (3) as an essential constituent unit, and is a unit that gives the cationic monomer unit. It is a homopolymer of a monomer or a copolymer of the monomer and a nonionic monomer. As the alkylene group having 1 to 4 carbon atoms R ⁴ in the general formula (3), a methylene group, an ethylene group, a propylene group, and among them ethylene group is preferred. The alkyl group having 1 to 4 carbon atoms R ⁵ to R ⁶ include a methyl group, an ethyl group, and a propyl group, and a methyl group, an ethyl group are preferable.
The anion Y ⁻ in the general formula (3) represents a halogen ion such as Cl ⁻ or Br ⁻ or a sulfate group of 1 / 2SO ₄ ²⁻ .

  Examples of the monomer that gives the cationic monomer unit represented by the general formula (3) include dialkylaminoalkyl (meth) acrylate cationic monomers, and specifically, dimethylaminoethyl (meth). Tertiary salts such as acrylates, dialkylaminoalkyl (meth) acrylates such as diethylaminoethyl (meth) acrylate and diethylamino-2-hydroxypropyl (meth) acrylate and tertiary salts such as sulfate, methyl chloride of dialkylaminoalkyl (meth) acrylate Examples include quaternary salts such as alkyl halide adducts such as adducts and aryl halide adducts such as benzyl chloride. In addition, hydrochloride salts such as dimethylaminopropyl (meth) acrylamide and the like, hydrochloride salts such as dialkylaminopropyl (meth) acrylamide and tertiary salts such as sulfate, and alkyl halide adducts such as methyl chloride adduct of dialkylaminopropyl (meth) acrylamide. And quaternary salts such as halogenated aryl adducts such as benzyl chloride adduct. Among these, dialkylaminoalkyl (meth) acrylate halogenated alkyl adducts are preferable, and dimethylaminoethyl acrylate methyl chloride adduct is particularly preferable.

Nonionic monomers that can be copolymerized with a monomer that gives a cationic monomer unit include dialkyl (meth) acrylamides such as (meth) acrylamide and dimethyl (meth) acrylamide, among which acrylamide is preferred. .
When the cationic polymer (b) is a copolymer, the content of the cationic monomer unit represented by the general formula (3) in the polymer is usually 1 mol% with respect to all the structural units of the polymer. Above, preferably 20 mol% or more, usually 99 mol% or less, preferably 90 mol% or less.
The molecular weight of the cationic polymer (b) in the present invention is not particularly limited as long as it is several million or more widely used as a polymer flocculant, and among these, about 2 million to 15 million or less. Those are preferred. The 0.5% salt viscosity is preferably 3 mPa · s or more and 200 mPa · s or less.
The cationic polymer (b) of the present invention can be produced by a known general polymerization method. For example, a monomer that gives a cationic monomer unit represented by the above general formula (3), If necessary, it is polymerized by a known method together with a nonionic monomer in the presence of a radical polymerization initiator such as potassium persulfate.

The anionic polymer (c) used in the present invention contains the anionic monomer unit represented by the general formula (4) and / or (5) as an essential constituent unit. It is a homopolymer of a monomer giving a monomer unit, or a copolymer of the monomer and a nonionic monomer and / or an anionic monomer different from the monomer.
In the general formulas (4) and (5), examples of the alkali metal ion represented by Z include Na ⁺ and K ⁺ .
Examples of the monomer that gives the monomer unit represented by the general formula (4) include acrylic acid (salt) and methacrylic acid (salt). Among them, acrylic acid (salt) is preferable.
Nonionic monomers that can be copolymerized with the monomer that gives the monomer unit represented by the general formula (4) and / or (5) include (meth) acrylamide, N, N-dimethyl (meth) acrylamide, and the like. Among them, acrylamide is preferable. Examples of the anionic monomer that gives an anionic monomer unit other than the monomer unit represented by the general formula (4) and / or (5) include itaconic acid (salt), maleic acid (salt), Examples thereof include styrene sulfonic acid (salt).

When the anionic polymer (c) is a copolymer, the content of the anionic monomer unit represented by the general formula (4) and / or the general formula (5) in the polymer is the total composition of the polymer. It is usually 0.1 mol% or more, preferably 1 mol% or more, and usually 99 mol% or less, preferably 20 mol% or less, based on the unit.
The molecular weight of the anionic polymer (c) in the present invention is not particularly limited as long as it is several million or more widely used as a polymer flocculant, and among these, about 5 million to 20 million. Those are preferred. The 0.5% salt viscosity is preferably 30 mPa · s or more and 400 mPa · s or less.
The anionic polymer (c) of the present invention can be produced by a known general polymerization method in the same manner as the cationic polymer (b).

The nonionic polymer (d) in the present invention contains the monomer unit represented by the general formula (6) as an essential constituent unit, and is a polymer of a (meth) acrylamide monomer. As the nonionic polymer, polyacrylamide is particularly preferable.
The molecular weight of the nonionic polymer (d) in the present invention is not particularly limited as long as it is several million or more widely used as a polymer flocculant, and among these, about 5 million to 20 million. Those are preferred. The 0.5% salt viscosity is preferably 30 mPa · s or more and 400 mPa · s or less.

The amphoteric copolymer (e) in the present invention comprises an anionic monomer unit represented by the general formula (4) as an anionic group and a cationic property represented by the general formula (3) as a cationic group. The polymer (e-1) containing a monomer unit as an essential constituent unit, or the polymer (e-1) further comprising a nonionic monomer unit represented by the general formula (6) as a constituent unit It is a polymer (e-2) containing.
The amphoteric copolymer (e) contains a carboxyl group derived from a monomer that gives an anionic monomer unit of the general formula (4) as an anionic group, but the sulfonic acid represented by the general formula (5) It may contain a group, and may further contain a carboxyl group derived from another monomer. Specifically, the monomer that gives the anionic monomer unit is (meth) acrylic acid (salt), but 2-acrylamido-2-methylpropanesulfonic acid (salt), itaconic acid (salt) Salt), maleic acid (salt), styrene sulfonic acid (salt) and the like.

  In addition, the cationic group is derived from a monomer that gives the cationic monomer unit represented by the general formula (3). As the monomer, a dialkylaminoalkyl (meth) acrylate-based cationic unit is used. In particular, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, and dialkylaminoalkyl (meth) acrylate hydrochlorides such as diethylamino-2-hydroxypropyl (meth) acrylate and Quaternary salts such as tertiary salts such as sulfates, halogenated alkyl adducts such as methyl chloride adducts of dialkylaminoalkyl (meth) acrylates, and aryl halide adducts such as benzyl chloride, and the like. In addition, hydrochloride salts such as dimethylaminopropyl (meth) acrylamide and the like, hydrochloride salts such as dialkylaminopropyl (meth) acrylamide and tertiary salts such as sulfate, and alkyl halide adducts such as methyl chloride adduct of dialkylaminopropyl (meth) acrylamide. And quaternary salts such as halogenated aryl adducts such as benzyl chloride adduct. These can use 1 type (s) or 2 or more types.

Examples of the nonionic monomer unit represented by the general formula (6) include (meth) acrylamide, N, N-dimethyl (meth) acrylamide and the like.
The molecular weight of the amphoteric copolymer (e) in the present invention is not particularly limited as long as it is several million or more widely used as a polymer flocculant, and among them, those having a molecular weight of about 2 million to 15 million Is preferred. The 0.5% salt viscosity is preferably 3 mPa · s or more and 200 mPa · s or less.

The cationic polymer (b), anionic polymer (c), nonionic polymer (d), and amphoteric copolymer (e) used in the present invention can be produced by producing these polymers. Any known polymerization method can be applied, and examples thereof include precipitation polymerization, bulk polymerization, dispersion polymerization, and aqueous solution polymerization, and are not particularly limited.

  The sludge dewatering agent of the present invention comprises a polymer (a) containing the amidine structural unit and at least one polymer selected from the polymers (b) to (e) in the group (A) from 99: 1 to 91. : It is necessary to contain in the ratio of 9 (mass ratio). When the amount of the polymer in the group (A) exceeds this ratio, the cake dehydration rate after separation tends to deteriorate, and when it is too small, the effect of the present invention cannot be sufficiently achieved.

  In the sludge dehydrating agent of the present invention, the polymer (A) combined with the polymer (a) containing the amidine structural unit is preferably an anionic polymer (c) and an amphoteric copolymer (e). The ratio of the polymer (a) to the anionic polymer (c) or the amphoteric copolymer (e) is preferably 91: 9 to 95: 5.

In the sludge dewatering method of the present invention, the sludge dewatering agent (polymer flocculant) of the present invention, that is, the polymer (a) containing the amidine ring structural unit, the cationic polymer (b), At least one polymer selected from the group (A) consisting of an anionic polymer (c), a nonionic polymer (d), and an amphoteric copolymer (e) is added at a predetermined ratio and mixed to agglomerate. Then, the obtained aggregate is subjected to a mechanical dehydration treatment.
According to the dehydration method using the polymer flocculant of the present invention, sludge aggregation flocs are usually formed by adding the polymer flocculant to sludge, and the aggregate is dehydrated. The flocculant and sludge are mixed in a mixing tank, and the formed floc floc is solid-liquid separated with a dehydrator. The form of the dehydrator is not particularly limited, but usually a belt press dehydrator, a centrifugal decanter dehydrator, a screw press dehydrator, a filter press dehydrator, etc. are named.

  The amount of the polymer flocculant of the present invention added to the sludge varies depending on the properties of the sludge and is not particularly limited. Usually, the total amount of the polymer flocculant added is usually 0.1% of the total solid content in the sludge. It is at least mass%, preferably at least 0.2 mass%, usually at most 3 mass%, preferably at most 2 mass%. When the addition amount is less than 0.1% by mass, sufficient aggregation performance cannot be obtained, and even when the amount exceeds 3% by mass, the expected effect cannot be obtained.

  An amidine polymer (a) constituting the sludge dehydrating agent of the present invention, a cationic polymer (b) selected from the group (A), an anionic polymer (c), a nonionic polymer (d), and The method for adding each polymer flocculant of the amphoteric copolymer (e) is not particularly limited, but is usually added as a solution. In this case, each polymer flocculant may be added individually or as a single solution, but it is preferable to add a predetermined amount of polymer flocculant in advance.

  The present invention can be effectively applied to the treatment of sludge that may cause scum in the dewatering treatment liquid. Examples of the sludge to be treated include digested sludge, surplus sludge, raw sludge, mixed sludge, and livestock sludge. Food sludge, chemical sludge and the like.

  Hereinafter, the present invention will be described in detail with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

(Synthesis example of amidine structure polymer)
(Synthesis Example 1 (P-1))
A mixture of 6 g of a mixture of acrylonitrile and N-vinylformamide (molar ratio 55:45) and 34 g of demineralized water was placed in a 50 ml four-necked flask equipped with a stirrer, a nitrogen inlet tube, and a condenser tube. The temperature was raised to 60 ° C. while stirring in nitrogen gas, and 0.12 g of a 10% by mass 2,2′-azobis (2-amidinopropane) dihydrochloride aqueous solution was added, and the mixture was further maintained for 3 hours. A suspension in which the coalescence precipitated was obtained. 20 g of water was added to the suspension, and 2 equivalents of concentrated hydrochloric acid was added to the formyl group of the polymer, and kept at 100 ° C. for 4 hours to obtain a yellow high-viscosity liquid. This was added to a large amount of acetone, the polymer was precipitated, chopped, dried at 60 ° C. for 1 night and pulverized to obtain a water-soluble cationic polymer.

(composition)
The amidine structure polymer P-1 was dissolved in heavy water, and a ¹³ C-NMR spectrum was measured with an NMR spectrometer (manufactured by JEOL Ltd., 270 MHz). The composition of each unit was calculated from the integrated value of the peak corresponding to each repeating unit of the ¹³ C-NMR spectrum. The structural units of the general formulas (1) and (2) were determined as the total amount without distinction. The results are shown in Table 1.

構成成分の略号は下記を示す。
アミジン：アミジン塩酸塩単位
ＮＶＦ：Ｎ−ビニルホルムアミド単位
ＡＮ ：アクリロニトリル単位
ＶＡＭ：ビニルアミン塩酸塩単位

The abbreviations of the constituent components are as follows.
Amidine: Amidine hydrochloride unit NVF: N-vinylformamide unit AN: Acrylonitrile unit VAM: Vinylamine hydrochloride unit

(Synthesis examples of cationic and amphoteric polymers)
(Synthesis Example 2 (R-1))
In a 1 liter Erlenmeyer flask, acrylic acid 6 mol%, dimethylaminoethyl acrylate / methyl chloride quaternary salt 13 mol%, dimethylaminoethyl methacrylate / methyl chloride quaternary salt 1 mol%, acrylamide 80 mol%, hypophosphorous acid 15 ppm ( Hereinafter, 960 g of an aqueous monomer solution (total monomer concentration: 40% by weight) containing ppm was indicated.
Under light shielding, 75 ppm of 2-hydroxy-2-methyl-1-phenylpropan-1-one was added to the monomer aqueous solution, and the Erlenmeyer flask was placed in a constant temperature water bath at 15 ° C., and dissolved oxygen in the aqueous solution with nitrogen gas as it was for 30 minutes. Was replaced.

  A container was prepared in which a rubber rod with a side of a cross section of 24 mm was attached to the periphery of a stainless steel plate having a thickness of 1 mm so that the inner bottom surface of the stainless steel plate was a 200 × 200 mm square. A light-transmitting film having a thickness of 16 μm (a laminated film made of polyethylene terephthalate having a thickness of 12 μm and polyvinylidene chloride having a thickness of 4 μm) was laid on the inside of the container, and an aqueous solution of a polymerizable monomer was supplied onto the film. . The upper surface of the aqueous solution was covered with a light transmissive film of the same kind as described above so as to be in contact with the aqueous solution. The thickness of the layer made of the monomer aqueous solution was 22 mm. Further, the back side of the stainless steel plate was cooled by spraying water at 10 ° C. before supplying the monomer aqueous solution, and the temperature of the stainless steel plate was adjusted to 10 ° C. Furthermore, spraying water at 10 ° C. was continued until the polymerization was completed.

A 20 W fluorescent chemical lamp was installed above the container to which the monomer aqueous solution was supplied. A fluorescent chemical lamp that had been adjusted in advance so that the irradiation intensity was 5 W / m ^{2 on the} surface of the aqueous solution was lit for 3 minutes. Next, a fluorescent chemical lamp adjusted to have an irradiation intensity of 0.5 W / m ^{2 on the} surface of the aqueous solution was lit for 30 minutes. Further, a fluorescent chemical lamp adjusted to have an irradiation intensity of 45 W / m ^{2 on the} surface of the aqueous solution was lit for 15 minutes to complete the polymerization, and a gel-like water-soluble polymer sheet was obtained.
The obtained gel-like water-soluble polymer sheet was chopped into 10 × 5 × 1.5 mm with scissors and dried at 60 ° C. for 16 hours. The obtained dry pellets were pulverized with a pulverizer to obtain a powdered water-soluble polymer.

  The brands other than K-1 were subjected to the same operation as in Synthesis Example 2 except that the constituent components, composition, and preparation liquid composition were adjusted to obtain a powdery water-soluble polymer. The charge composition table is shown in Table 2. K-1 was prepared by adjusting the components and composition as shown in Table 2 and changing 2-hydroxy-2-methyl-1-phenylpropan-1-one added to the monomer aqueous solution from 75 ppm to 500 ppm. Except for the above, the same operation as in Synthesis Example 2 was performed to obtain a powdery water-soluble polymer.

構成成分の略号は下記を示す。
ＤＭＣ：ジメチルアミノエチルメタクリレート・メチルクロライド４級塩
ＤＭＥ：ジメチルアミノエチルアクリレート・メチルクロライド４級塩
ＡＡｍ：アクリルアミド
ＡＡ ：アクリル酸

The abbreviations of the constituent components are as follows.
DMC: dimethylaminoethyl methacrylate / methyl chloride quaternary salt DME: dimethylaminoethyl acrylate / methyl chloride quaternary salt AAm: acrylamide AA: acrylic acid

(Synthesis example of anionic / nonionic polymer)
(Synthesis Example 3 (A-1))
In a 5-liter dewar, 3000 g of an aqueous solution containing 77 mol% of acrylamide and 23 mol% of sodium acrylate in terms of acrylic acid was placed. The inside of the dewar was replaced with nitrogen gas, and the temperature was adjusted to 10 ° C. As a polymerization initiator, 2,2′-azobis (2-amidinopropane) dihydrochloride (200 ppm), ammonium persulfate (APS) (10 ppm), and sodium bisulfite (SHS) (100 ppm) were added, and acrylamide was subjected to adiabatic polymerization. The obtained gel water-soluble polymer was cut with a meat grinder and dried at 60 ° C. for 16 hours. The obtained dry pellets were pulverized with a pulverizer to obtain a powdered water-soluble polymer.
A powdery water-soluble polymer was obtained in the same manner as in Synthesis Example 3 except that the components, composition, and preparation liquid composition were adjusted. The charged composition table is shown in Table 3.

[0.5% salt viscosity]
0.5% by mass of the polymer flocculant was dissolved in an aqueous solution containing 4% by mass of sodium chloride, and after complete dissolution, measurement was performed with a B-type viscometer at a rotational speed of 60 rpm and 25 ° C.

The polymer flocculant was evaluated by the following test method.
(Test method)
A certain amount of sludge was taken in a beaker, a predetermined amount of polymer flocculant was added thereto, and after stirring for 20 seconds at 1000 rpm with a Suriwan motor, solid-liquid separation was performed with a 48 mesh nylon filter cloth. . The separated sludge was drained by hand drawing using a 48 mesh nylon filter cloth, pressed at 0.1 MPa pressure for 60 seconds, and then the cake was dried at 105 ° C. for 20 hours. The moisture content was determined by measuring the weight of the cake before and after drying.
30 ml of the treatment liquid separated into solid and liquid was dispensed into a 100 ml glass beaker, and 0.5 ml of sludge was added while stirring at a rotational speed of 580 rpm with a magnetic stirrer to form a re-agglomerated floc, and the floc diameter was recorded.

(Evaluation)
When the obtained re-agglomerated floc was poured into a glass tube having an inner diameter of 5 mm together with the treatment liquid, the re-agglomerated floc of Comparative Example 1 (single use of the polymer (a) containing an amidine structural unit as a polymer flocculant) Only clogged. Therefore, the diameter of the re-agglomerated floc of Comparative Example 1 was used as a reference, and a floc diameter smaller than this diameter was effective against clogging.
In addition, the upper limit was set to the value of cake moisture content of Comparative Example 1 + 0.5%, and the range was less than that, so that the moisture content of the cake was not affected.

(Examples 1-35) and (Comparative Examples 1-6)
Using digested sludge (pH 7.1, solid content 27,700 mg / l) of A city public sewage treatment plant, a series of tests were conducted by the above test method. The results are shown in Tables 4 to 7 below.
In the blending ratio of the polymer flocculant, P-1 [polymer (a) of the present application]: other flocculants [flocculants (b) to (e) of group (A) of the present application] is 90:10. In Comparative Example 2, Comparative Example 3, Comparative Example 4, Comparative Example 4, Comparative Example 5, and Comparative Example 6, the moisture content of the cake exceeds the range of + 0.5% relative to the moisture content of Comparative Example 1, and the moisture content deteriorates. Was seen. From the above, it can be seen that the reaggregation floc diameter is smaller than that of Comparative Example 1 without the deterioration of the moisture content in the examples. Therefore, it was judged that this prescription is effective for adhesion and clogging of piping.

Claims (4)

A polymer (a) containing an amidine structural unit represented by the following general formula (1) and / or (2), a cationic polymer (b) of the following group (A), an anionic polymer (c), It contains at least one polymer selected from the nonionic polymer (d) and the amphoteric copolymer (e), and the mass ratio of the polymer (a) and the polymer selected from the group (A) is 99. : 1 to 91: 9, a sludge dehydrating agent.
Polymer (a)

(In formulas (1) and (2), R ^{1 to} R ² are each a hydrogen atom or a methyl group, and X ⁻ is an anion.)
(A) group:
A cationic polymer (b);
Polymer (b) containing a cationic monomer unit represented by the following general formula (3) as an essential constituent unit

(In the formula (3), the R ³ is a hydrogen atom or a methyl group, R ⁴ is an alkylene group having 1 to 4 carbon atoms, R ⁵ is an alkyl group having 1 to 4 carbon atoms, R ⁶ is a hydrogen atom, C 1 -C to 4 alkyl group or a benzyl group, a is -O- or -NH-, Y ^- represents an anion).
Anionic polymer (c);
Polymer (c) comprising an anionic monomer unit represented by the following general formula (4) and / or (5) as an essential constituent unit

(In formula (4), R ⁷ is hydrogen or a methyl group. Z represents H ⁺ or an alkali metal ion.)

(In formula (5), Z represents H ⁺ or an alkali metal ion.)
Nonionic polymer (d);
A polymer (d) composed of a nonionic monomer unit represented by the following general formula (6),

(In the formula (6), R ⁸ is .R ^9, R ¹⁰ is hydrogen or a methyl group, represents hydrogen or an alkyl group having 1 to 4 carbon atoms and may be the same or different.)
as well as,
Amphoteric copolymer (e);
Polymer (e) containing the cationic monomer unit represented by the general formula (3) and the anionic monomer unit represented by the general formula (4) and / or (5) as essential constituent units -1) or a polymer (e-2) in which the polymer (e-1) further contains a nonionic monomer unit represented by the general formula (6) as a constituent unit   The sludge dehydrating agent according to claim 1, wherein the polymer selected from the group (A) is an anionic polymer (c) and / or an amphoteric copolymer (e).   The polymer selected from the group (A) is an amphoteric copolymer (e), and the mass ratio of the polymer (a) and the amphoteric copolymer (e) is 95: 5 to 91: 9. The sludge dehydrating agent according to claim 1 or 2.   A sludge dewatering method comprising adding the sludge dewatering agent according to any one of claims 1 to 3 to sludge and then performing dewatering.