JP2002136807A - Sludge dewatering agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dehydrating agent for sludge, having excellent coagulation performance and dehydrating ability, which is capable of forming coarse coagulated flocks and reducing the water content in a dehydrated cake when it is used for treating waste water, especially sewage water. SOLUTION: For the dehydrating agent for sludge, containing a cationic polymer coagulant and an anionic polymer coagulant, the cationic polymer coagulant, which is a salt of poly'(vinylimidazolinic acid), preferably a salt of a branched poly(vinylimidazolinic acid) having a Huggins constant k' of 0.2 to 0.5, when the Huggins constant is measured at 30 deg.C in an aqueous sodium chloride solution of 0.1 mol/l, and a limiting viscosity number [η] of 2 to 15, is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a sludge dewatering agent comprising a cationic polymer flocculant and an anionic polymer flocculant, and more particularly, the cationic polymer flocculant comprises a branched polyvinyl imidazophosphate. The present invention relates to a sludge dewatering agent comprising:

[0002]

2. Description of the Related Art Cationic polymer flocculants are used for sewage treatment,
It is used as a sludge dewatering agent in human waste treatment, food, paper / pulp, and various other industrial wastewater treatments. That is, a cationic polymer flocculant is added to and mixed with sludge generated after biological treatment of wastewater to form flocculated flocs, and the cake is dewatered after solid-liquid separation, and the resulting dewatered cake is incinerated or landfilled. Is processed by Among these wastewater treatments, a cationic polymer flocculant is used alone as a sludge dewatering agent for sewage treatment containing a large amount of organic matter. In recent years, among these wastewater treatments, especially in sewage treatment, sludge tends to be hardly coagulated and hardly dewatered due to the improvement of living standards and the extension of sludge pipes accompanying the integration of treatment plants. . When the sludge is hard to coagulate, there is a problem of treatment cost because the amount of sludge that can be treated per unit time is reduced.
When the sludge is hardly dewatered, the water content of the dewatered cake increases, the processing costs such as the volume of the dewatered cake and the incineration cost increase, and the amount of carbon dioxide gas generated due to the increase in the amount of heavy oil required for incineration And other environmental issues. In order to solve these problems, a demand for a sludge dewatering agent having excellent dewatering performance as well as flocculation performance is increasing.

[0003] The properties of polymer materials greatly depend on their constituent units, molecular weight, molecular weight distribution, degree of branching, and the like. It is also known that the performance as a polymer flocculant is remarkably improved by increasing the molecular weight.

Hitherto, polyvinylimidazoline and / or an acid salt thereof has been used for a flocculant (Japanese Patent Publication No. Sho 4).
2-9653), when used alone as a sludge dewatering agent for sewage treatment, it could not be said that both coagulation performance and dewatering performance were sufficient. A sludge dewatering method has been proposed in which polyvinyl imidazoline hydrochloride and an anionic polymer flocculant are added to a specific organic sludge (Japanese Patent Laid-Open No. 57-13 / 1979).
No. 5099), although the coagulation performance was improved, the improvement of the dewatering performance was not sufficient.

Further, a polymer coagulant comprising a novel copolymer has been proposed (JP-A-2000-191733).
No.), although the coagulation performance was improved, the improvement of the dewatering performance was insufficient.

[0006]

Conventionally, polyvinyl imidazophosphate has not been said to be a sludge dewatering agent having excellent coagulation performance and dewatering performance when used as a sludge dewatering agent for wastewater treatment, particularly for sewage treatment. .

In wastewater treatment, especially in sewage treatment, sludge generated by biological treatment tends to be hardly coagulated and hardly dehydrated. If sludge is hardly coagulated, the amount of sludge that can be treated per unit time However, when sludge is hardly dewatered, the water content of the dewatered cake increases, which causes problems such as increased dewatered cake volume and increased incineration costs, as well as incineration. Sludge dewatering with excellent coagulation performance and dewatering performance in the treatment of sludge that is difficult to coagulate and hard to dewater due to environmental problems such as an increase in the amount of carbon dioxide generated due to an increase in the amount of heavy oil The agent was strongly desired.

Accordingly, an object of the present invention is to form coarse flocs when used for wastewater treatment, especially sewage treatment,
It is another object of the present invention to provide a sludge dewatering agent which is excellent in coagulation performance and dewatering performance and reduces the water content of a dewatered cake.

[0009]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found a sludge dewatering agent composed of a cationic polymer flocculant and an anionic polymer flocculant. As a result, the present invention has been completed.

That is, the present invention provides a sludge dewatering agent comprising a cationic polymer flocculant and an anionic polymer flocculant, wherein the cationic polymer flocculant is a polyvinyl imidazophosphate having the following chemical formula (1): So,
Huggins constant k ′ in the following formula (1) measured at 30 ° C. in a 0.1 mol / l sodium chloride aqueous solution.
Is a cationic polymer flocculant comprising a branched polyvinyl imidazophosphate, characterized by having a limiting viscosity number [η] of 2 to 15 and a sludge dewatering characteristic. Agent.

[0011]

Embedded image

(Wherein, X ^- represents a chloride anion, a sulfate anion, a carbonate anion, an anion of paratoluenesulfonic acid, an anion of formic acid, an anion of acetic acid, or an anion of propionic acid.)

[0013]

(Equation 2)

Where η _sp is the specific viscosity, C is the polymer concentration,
[Η] represents the limiting viscosity number, and k ′ represents the Huggins constant. Hereinafter, the present invention will be described in detail.

The sludge dewatering agent of the present invention is a sludge dewatering agent comprising a cationic polymer flocculant and an anionic polymer flocculant, wherein the cationic polymer flocculant comprises polyvinyl imidazolic acid represented by the above chemical formula (1). Salt,
Huggins constant k ′ in the above formula (1) measured in a 0.1 mol / l aqueous sodium chloride solution at 30 ° C.
Is a cationic polymer flocculant comprising a branched polyvinyl imidazophosphate, characterized by having a limiting viscosity number [η] of 2 to 15 and a sludge dewatering characteristic. Agent.

The degree of branching of the branched polyvinyl imidazophosphate, which is a cationic polymer flocculant used in the sludge dewatering agent of the present invention, is determined by Huggi in the above formula (1).
It is represented by the ns constant k '. Huggins constant k '
Is a constant obtained from a solution viscosity measurement of a polymer material, and is widely used as a method for examining the degree of branching of a polymer material.
It is known that the Huggins constant k 'shows a large value, and the Huggins constant k' shows a small value as the degree of branching is small. (Journal of Polymer Science, Vol. 10, 185 (1953), Polymer Chemistry, Vol. 10, 512 (1953)) The branched polyvinyl imidazophosphate which is a cationic polymer flocculant used in the sludge dewatering agent of the present invention is: , 0.1
The Huggins constant k ′ in the above formula (1) measured at 30 ° C. in a mol / l aqueous sodium chloride solution is 0.2 to 0.5, preferably 0.3 to 0.5,
Furthermore, from the viewpoint of performance, it is particularly preferably 0.35 to 0.45
It is. If it is less than 0.2, the performance is insufficient.
If it exceeds 5, the solubility in water is undesirably reduced.

The branched polyvinyl imidazophosphate, which is a cationic polymer flocculant used in the sludge dewatering agent of the present invention, is prepared by adding 30 mol / l of an aqueous sodium chloride solution to 30 mol / l.
The intrinsic viscosity number [η] in the above formula (1) measured at ° C. is usually 2 to 15, and preferably 4 to 10 from the viewpoint of performance and ease of handling. If it is less than 2, the performance is insufficient, and if it is more than 15, the viscosity of the waste water after being added to the waste water becomes extremely viscous, making it difficult to handle.

The branched polyvinyl imidazoline salt is a cationic polymer flocculating agent used in the sludge dehydrating agent of the present invention, X in the above formula (1) in ^- is a chlorine anion, sulfate anion, carbonate An anion, an anion of p-toluenesulfonic acid, an anion of formic acid, an anion of acetic acid, or an anion of propionic acid, preferably a chlorine anion or an anion of acetic acid from the viewpoint of performance and ease of handling in wastewater treatment. Ions or sulfate anions, particularly preferably chloride anions.

The method for producing a branched polyvinyl imidazophosphate, which is a cationic polymer flocculant used in the sludge dewatering agent of the present invention, is obtained by reacting a branched polyacrylonitrile with ethylenediamine in the presence of a catalyst. And contacting the polymer with an acid.

The catalyst used in the method for producing a branched polyvinyl imidazophosphate, which is a cationic polymer flocculant used in the sludge dewatering agent of the present invention, is an ammonium chloride and / or amine hydrochloride. The amine is not particularly limited, for example, aliphatic amines such as methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, alicyclic amines such as piperidine, pyrrolidine, cyclohexylamine, pyridine, aniline And aromatic amines such as dimethylaniline and diethylaniline, and polyamines such as ethylenediamine and diethylenetriamine.
In the production method of the present invention, since ethylenediamine is used as a reaction raw material, it may be converted into a hydrochloride of ethylenediamine by adding hydrogen chloride to the reaction system.

In the method for producing a branched polyvinyl imidazophosphate which is a cationic polymer flocculant used in the sludge dewatering agent of the present invention, the raw material used for the branched polyacrylonitrile is not particularly limited. Considering the performance of the imidazophosphate as a flocculant, the solubility of the flocculant in water, the reactivity with ethylenediamine, etc., 30% of N, N-dimethylformamide
Huggins in the above formula (1) measured at ° C.
When the constant k ′ is 0.2 to 0.5 and the intrinsic viscosity [η] is 2 to
A branched polyacrylonitrile of 15 is preferred. More preferably, the Huggins constant k ′ is 0.3 to 0.5.
5, the intrinsic viscosity [η] is from 5 to 15, particularly preferably the Huggins constant k ′ is from 0.3 to 0.5, and the intrinsic viscosity [η] is from 8 to 15.

In the method for producing a branched polyvinyl imidazophosphate which is a cationic polymer flocculant used in the sludge dewatering agent of the present invention, the branched polyacrylonitrile used as a raw material is a known one using an acrylonitrile monomer. Can be obtained. That is, as a specific polymerization method, an ordinary radical polymerization method is used. For example, a slurry polymerization method using a water-soluble redox polymerization initiator in an aqueous medium, dimethyl sulfoxide, N, N
Solution polymerization, suspension polymerization, or emulsion polymerization using a solvent such as -dimethylformamide or N, N-dimethylacetamide.

In the process for producing a branched polyvinyl imidazophosphate, which is a cationic polymer flocculant used in the sludge dewatering agent of the present invention, the reaction temperature between the branched polyacrylonitrile and ethylenediamine is usually from 60 to 200 ° C.
, And more preferably in the range of 70 to 180 ° C. Although the reaction can be carried out at a temperature higher than 200 ° C., thermal decomposition of the raw material polyacrylonitrile may occur. On the other hand, in the reaction below 60 ° C,
Since the reaction rate becomes extremely slow, it is necessary to increase the amount of the catalyst, which is not very economical.

In the method for producing a branched polyvinyl imidazophosphate, which is a cationic polymer flocculant used in the sludge dewatering agent of the present invention, the reaction between the branched polyacrylonitrile and ethylenediamine is usually carried out in a liquid phase, and the raw material is used. What is necessary is just to be able to maintain a liquid state, a solution state, and a suspension state, and it can be performed under normal pressure or under pressure. In this reaction, since ammonia is generated during the reaction, the pressure increases when the pressure is increased. However, the generated ammonia can be removed during the reaction, or can be removed after the reaction is completed. When the reaction temperature exceeds the boiling point of the raw materials, a method of performing the reaction under pressure, providing a condenser, or supplying the raw materials little by little can be employed.

In the method for producing a branched polyvinyl imidazophosphate which is a cationic polymer flocculant used in the sludge dewatering agent of the present invention, the reaction between the branched polyacrylonitrile and ethylenediamine may be carried out with or without using a solvent. good. The solvent can be used without any particular limitation as long as it is inert to the reaction conditions.

In the method for producing a branched polyvinyl imidazophosphate which is a cationic polymer flocculant used in the sludge dewatering agent of the present invention, the branched polyvinyl imidazophosphate is obtained by reacting a branched polyacrylonitrile with ethylenediamine. It is obtained by contacting the obtained polymer with an acid. Examples of the acid include hydrochloric acid, sulfuric acid, carbonic acid, paratoluenesulfonic acid, formic acid, acetic acid and propionic acid. The method for bringing the acid into contact with the polymer obtained by the reaction of the branched polyacrylonitrile and ethylenediamine is not particularly limited, but these are added to the reaction system at the end of the reaction between the branched polyacrylonitrile and ethylenediamine. A method in which an acid is added and brought into contact, a method in which a polymer obtained by the reaction of branched polyacrylonitrile and ethylenediamine is made into a solid or a solution dissolved in a solvent, and a method in which the polymer is brought into contact with an acid, or a reaction between branched polyacrylonitrile and ethylenediamine Of the polymer obtained by the above method, and contacting the desalted polymer with an acid.

In the process for producing a branched polyvinyl imidazophosphate, which is a cationic polymer flocculant used in the sludge dewatering agent of the present invention, X in the aforementioned chemical formula (1)
^In the production of a branched polyimidazophosphate in which-is a chlorine anion, a polymer obtained by reacting a branched polyacrylonitrile with ethylenediamine may be brought into contact with hydrochloric acid, but it may be contacted with polyacrylonitrile. By making the amount of ammonium chloride and / or amine hydrochloride used in the reaction with ethylenediamine equal to or more than the amount of acrylonitrile units in the raw material polyacrylonitrile, it is possible to avoid contact with hydrochloric acid further. Good.

The method for producing the branched polyvinyl imidazophosphate, which is a cationic polymer flocculant used in the sludge dewatering agent of the present invention, may be carried out in a continuous reaction, a batch reaction or a semi-batch reaction. Is also good. In addition, the reaction can be carried out using a fixed bed or a suspension bed.

In the sludge dewatering agent of the present invention, another cationic polymer can be used in combination with the above-mentioned branched polyvinyl imidazophosphate as a cationic polymer flocculant.
Other cationic polymers that can be used in combination include Mannich-modified polyacrylamide, Hoffmann decomposed polyacrylamide, polyamidoamine, polyethyleneimine, polydiallyldialkylammonium salt, chitosan and salts thereof, and represented by the following chemical formula (2). A polymer containing a unit to be

[0030]

Embedded image

(Wherein R ¹ represents hydrogen or a methyl group;
R ² and R ³ each independently represent hydrogen or an alkyl group having 1 to 4 carbon atoms, R ⁴ represents hydrogen, an alkyl group having 1 to 4 carbon atoms or a benzyl group, and A represents —O— or —NH. -, B stands represents an alkylene group having 1 to 4 carbon atoms, Y ^- represents a chlorine anion, bromine anion, iodine Motokage ion, sulfate anion or CH ₃ SO ₄ ^- represents a. Or a polymer having a vinylamine unit represented by the following chemical formula (3);

[0032]

Embedded image

(Wherein, Z ^- is a chlorine anion, a bromine anion, an iodine anion, a sulfate anion, a carbonate anion,
Represents an anion of paratoluenesulfonic acid, an anion of formic acid, or an anion of acetic acid. ) Each of these can be used alone or in combination of two or more.

In the polymer containing a unit represented by the above chemical formula (2) which can be used in combination with the sludge dewatering agent of the present invention, R ¹ in the formula is hydrogen or a methyl group, and R ² and R ³ are each Independently, hydrogen or methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s
carbon number 1-4 such as ec-butyl group, tert-butyl group, etc.
R ⁴ is hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl,
An alkyl group having 1 to 4 carbon atoms such as an isobutyl group, a sec-butyl group and a tert-butyl group, or a benzyl group.
When R ² , R ³ , and R ⁴ are alkyl groups having 5 or more carbon atoms, the solubility of the polymer represented by the chemical formula (2) in water is reduced, or the polymer is used as a component of the flocculant of the present invention. In such a case, the aggregation performance is unfavorably reduced, and R ² , R ³ , and R ⁴ are preferably methyl groups in view of the aggregation performance. A in the formula is -O- or -NH-, B is a methylene group,
1 to 1 carbon atoms such as ethylene group, propylene group and butylene group
4 wherein the propylene group and the butylene group may be linear or branched. When B is an alkylene group having 5 or more carbon atoms, the solubility of the polymer represented by the chemical formula (2) in water is reduced, or the coagulation performance when used as a component of the coagulant of the present invention is reduced. However, ethylene groups are preferred in terms of aggregation performance.

[0035] Polymers containing units represented by the chemical formula (2) that can be used in combination with the sludge dehydrating agent of the present invention, Y in the aforementioned formula (2) in ^- a chlorine anion, bromine anion, iodine It is an anion, a sulfate anion or an anion such as CH ₃ SO ₄ ^— . Particularly preferred is a chlorine anion from the viewpoint of aggregation performance.

The polymer containing a unit represented by the above formula (2) which can be used in combination with the sludge dewatering agent of the present invention is a polymer containing a cationic group corresponding to the unit represented by the above formula (2). Polymer obtained from at least one kind selected from the group of monomers and / or at least one kind of monomer selected from the group of other monomers copolymerizable with the monomer. It is a polymer.

In the polymer containing a unit represented by the above formula (2) which can be used in combination with the sludge dewatering agent of the present invention, a monomer containing a cationic group corresponding to the unit represented by the above formula (2) Examples of the body include (meth) acryloyloxy (methyl, ethyl, propyl or butyl) trimethylammonium chloride, (meth) acryloyloxy (methyl, ethyl, propyl or butyl) trimethylammonium bromide, (meth) acryloyloxy (methyl, (Ethyl, propyl or butyl) trimethyl ammonium iodide, (meth) acryloyloxy (methyl, ethyl, propyl or butyl) trimethyl ammonium methyl sulfate, (meth) acryloyloxy (methyl, ethyl, propyl or butyl)
Diethylmethylammonium chloride, (meth) acryloyloxy (methyl, ethyl, propyl or butyl) diethylmethylammonium bromide, (meth)
Acryloyloxy (methyl, ethyl, propyl or butyl) diethylmethylammonium iodide, (meth) acryloyloxy (methyl, ethyl, propyl or butyl) diethylmethylammonium methylsulfate, (meth) acryloyloxy (methyl, ethyl,
Propyl or butyl) di-n-propylmethylammonium chloride, (meth) acryloyloxy (methyl, ethyl, propyl or butyl) di-n-propylmethylammonium bromide, (meth) acryloyloxy (methyl, ethyl, propyl or butyl) Di-n-
Propylmethylammonium iodide, (meth) acryloyloxy (methyl, ethyl, propyl or butyl) di-n-propylmethylammonium methylsulfate, (meth) acryloyloxy (methyl, ethyl, propyl or butyl) diisopropylmethylammonium chloride, (Meth) acryloyloxy (methyl, ethyl, propyl or butyl) diisopropylmethylammonium bromide, (meth) acryloyloxy (methyl, ethyl, propyl or butyl) diisopropylmethylammonium iodide, (meth) acryloyloxy (methyl, ethyl, propyl) Or butyl)
Diisopropylmethylammonium methyl sulfate, (meth) acryloyloxy (methyl, ethyl, propyl or butyl) di-n-butylmethylammonium chloride, (meth) acryloyloxy (methyl, ethyl, propyl or butyl) di-n-butylmethyl Ammonium bromide, (meth) acryloyloxy (methyl, ethyl, propyl or butyl) di-n-butylmethylammonium iodide, (meth) acryloyloxy (methyl, ethyl, propyl or butyl) di-n
-Butylmethylammonium methyl sulfate, (meth) acryloyloxy (methyl, ethyl, propyl or butyl) di-sec-butylmethylammonium chloride, (meth) acryloyloxy (methyl, ethyl, propyl or butyl) di-sec-butyl Methyl ammonium bromide, (meth) acryloyloxy (methyl, ethyl, propyl or butyl) di-sec-
Butylmethylammonium iodide, (meth) acryloyloxy (methyl, ethyl, propyl or butyl) di-sec-butylmethylammonium methylsulfate, (meth) acryloyloxy (methyl, ethyl, propyl or butyl) dimethylbenzylammonium chloride, (Meth) acryloyloxy (methyl,
Ethyl, propyl or butyl) diethylbenzylammonium chloride, (meth) acryloyloxy (methyl, ethyl, propyl or butyl) di-n-propylbenzylammonium chloride, (meth) acryloyloxy (methyl, ethyl, propyl or butyl) diisopropylbenzyl Ammonium chloride, (meth) acryloyloxy (methyl, ethyl, propyl or butyl) di-n-butylbenzylammonium chloride,
(Meth) acryloyloxyalkyl quaternary ammonium salts such as (meth) acryloyloxy (methyl, ethyl, propyl or butyl) di-sec-butylbenzylammonium chloride, (meth) acryloyloxy (methyl, ethyl, propyl or butyl) ) Dimethylamine, (meth) acryloyloxy (methyl, ethyl, propyl or butyl) diethylamine, (meth) acryloyloxy (methyl, ethyl, propyl or butyl) di-n-propylamine, (meth) acryloyloxy (methyl, ethyl) , Propyl or butyl) diisopropylamine, (meth) acryloyloxy (methyl, ethyl, propyl or butyl) di-n-butylamine, (meth) acryloyloxy (methyl, ethyl, propyl or butyl) di-se - hydrochloride salts such as butylamine, a bromate, iodate salts or sulfate (meth) acrylate salt of acryloyloxy alkyl tertiary amines, (meth) acryloyloxy (methyl, ethyl, propyl or butyl)
Acid salts of (meth) acryloyloxyalkyl primary amines which are hydrochlorides, bromates, iodates or sulfates of amines, (meth) acryloylamino (methyl, ethyl,
Propyl or butyl) trimethylammonium chloride, (meth) acryloylamino (methyl, ethyl, propyl or butyl) trimethylammonium bromide, (meth) acryloylamino (methyl, ethyl, propyl or butyl) trimethylammonium iodide, (meth) acryloylamino (Methyl, ethyl, propyl or butyl) trimethylammonium methyl sulfate, (meth) acryloylamino (methyl, ethyl, propyl or butyl) diethylmethylammonium chloride, (meth) acryloylamino (methyl, ethyl, propyl or butyl) diethylmethyl Ammonium bromide, (meth) acryloylamino (methyl,
(Ethyl, propyl or butyl) diethylmethylammonium iodide, (meth) acryloylamino (methyl, ethyl, propyl or butyl) diethylmethylammonium methylsulfate, (meth) acryloylamino (methyl, ethyl, propyl or butyl) di-n −
Propylmethylammonium chloride, (meth) acryloylamino (methyl, ethyl, propyl or butyl) di-n-propylmethylammonium bromide,
(Meth) acryloylamino (methyl, ethyl, propyl or butyl) di-n-propylmethylammonium iodide, (meth) acryloylamino (methyl, ethyl, propyl or butyl) di-n-propylmethylammonium methylsulfate, (Meth) acryloylamino (methyl, ethyl, propyl or butyl) diisopropylmethylammonium chloride, (meth) acryloylamino (methyl, ethyl, propyl or butyl) diisopropylmethylammonium bromide,
(Meth) acryloylamino (methyl, ethyl, propyl or butyl) diisopropylmethylammonium iodide, (meth) acryloylamino (methyl, ethyl, propyl or butyl) diisopropylmethylammonium methylsulfate, (meth) acryloylamino (methyl, ethyl) , Propyl or butyl) di-n-butylmethylammonium chloride, (meth) acryloylamino (methyl, ethyl, propyl or butyl) di-n-butylmethylammonium bromide, (meth)
Acryloylamino (methyl, ethyl, propyl or butyl) di-n-butylmethylammonium iodide, (meth) acryloylamino (methyl, ethyl, propyl or butyl) di-n-butylmethylammonium methylsulfate, (meth) acryloyl Amino (methyl, ethyl, propyl or butyl) di-sec-butyl methyl ammonium chloride, (meth) acryloylamino (methyl, ethyl, propyl or butyl) di-
sec-butylmethylammonium bromide, (meth) acryloylamino (methyl, ethyl, propyl or butyl) di-sec-butylmethylammonium iodide, (meth) acryloylamino (methyl, ethyl, propyl or butyl) di-sec-butyl Methylammonium methyl sulfate, (meth) acryloylamino (methyl, ethyl, propyl or butyl) dimethylbenzylammonium chloride, (meth) acryloylamino (methyl, ethyl, propyl or butyl) diethylbenzylammonium chloride, (meth) acryloylamino ( Methyl, ethyl, propyl or butyl) di-n-propylbenzylammonium chloride, (meth) acryloylamino (methyl, ethyl, propyl or butyl) diyl Propyl benzyl ammonium chloride, (meth) acryloyl amino (methyl,
Ethyl, propyl or butyl) di-n-butylbenzylammonium chloride, (meth) acryloylamino (methyl, ethyl, propyl or butyl) di-sec-
(Meth) such as butylbenzylammonium chloride
Acryloylaminoalkyl quaternary ammonium salts,
(Meth) acryloylamino (methyl, ethyl, propyl or butyl) dimethylamine, (meth) acryloylamino (methyl, ethyl, propyl or butyl) diethylamine, (meth) acryloylamino (methyl, ethyl, propyl or butyl) di-n -Propylamine,
(Meth) acryloylamino (methyl, ethyl, propyl or butyl) diisopropylamine, (meth) acryloylamino (methyl, ethyl, propyl or butyl)
Di-n-butylamine, (meth) acryloylamino (methyl, ethyl, propyl or butyl) di-sec-
Hydrochloride such as butylamine, bromate, iodate or sulfate (meth) acryloylaminoalkyl tertiary amine acid salt, (meth) acryloylamino (methyl,
(Ethyl, propyl or butyl) amine hydrochloride, bromate, iodate or sulfate (meth) acryloylaminoalkyl primary amine acid salt and the like, but are not limited thereto.

The polymer containing a unit represented by the above chemical formula (2) which can be used in combination with the sludge dewatering agent of the present invention preferably contains a unit of a (meth) acryloyloxyalkyl quaternary ammonium salt in terms of performance. It is a polymer, particularly preferably a homopolymer of methacryloyloxyethyltrimethylammonium chloride or a copolymer of methacryloyloxyethyltrimethylammonium chloride and acrylamide.

In the polymer containing the unit represented by the chemical formula (2) which can be used in combination with the sludge dewatering agent of the present invention, the content of the unit represented by the chemical formula (2) is determined by the content of the sludge to be treated. Although it is selected according to the properties, it is 10 to 100 mol% with respect to ordinary sewage sludge, preferably 40 to 100 mol%, particularly preferably 60 to 100 mol% in terms of performance.

The polymer containing the unit represented by the chemical formula (2) which can be used in combination with the sludge dewatering agent of the present invention is 1 mol / mol.
The intrinsic viscosity number [η] in the above formula (1) measured at 30 ° C. in 1 aqueous sodium chloride solution is usually 2 or more, and preferably 4 or more from the viewpoint of performance.

The polymer containing the unit represented by the chemical formula (2) which can be used in combination with the sludge dewatering agent of the present invention can be obtained by a known method using the corresponding monomer. That is, as a specific method, a normal radical polymerization method is used, for example, an aqueous solution polymerization method using a redox initiator in which a polymerization initiator such as persulfate or an oxidizing agent and a reducing agent are combined in an aqueous medium, An azo initiator in a medium of an organic solvent and water, an oil-soluble initiator such as an organic peroxide or a suspension polymerization method using the above-described redox initiator, an emulsion polymerization method, and the like, but are particularly limited. is not.

[0042] Polymers containing vinylamine units represented by the chemical formula (3) that can be used in combination with the sludge dehydrating agent of the present invention, Z in the above formula (3) in ^- a chlorine anion,
It is a bromine anion, an iodine anion, a sulfate anion, a carbonate anion, an anion of paratoluenesulfonic acid, an anion of formic acid, or an anion of acetic acid, and particularly preferably a chlorine anion in view of aggregation performance.

The polymer containing a vinylamine unit represented by the above chemical formula (3) which can be used together with the sludge dewatering agent of the present invention can be obtained by a polymer reaction of a polymer using a specific monomer. As a specific example, a method of subjecting a homopolymer of acrylamide or a copolymer of acrylamide and a copolymerizable monomer to Hoffmann decomposition, and a homopolymer of N-vinylformamide or N-vinylacetamide or a homopolymer of N-vinylformamide or N-vinylacetamide It can be obtained by a method of hydrolyzing a copolymer of each monomer and a copolymerizable monomer under acidic or basic conditions. Examples of these copolymerizable monomers include (meth) acrylonitrile, methacrylamide, (meth) acrylic acid, hydroxyethyl (meth) acrylate, N-vinylpyrrolidone, and the like. At least one selected from the following can be used.

In the polymer containing a vinylamine unit represented by the above chemical formula (3) which can be used in combination with the sludge dewatering agent of the present invention, the content of the unit represented by the above chemical formula (3) depends on the sludge to be treated. Although it is selected depending on the properties, it is 10 to 100 mol% with respect to the ordinary sewage sludge, and preferably 30 to 80 mol% in terms of performance.

The polymer containing a vinylamine unit represented by the above chemical formula (3) which can be used in combination with the sludge dewatering agent of the present invention can be obtained by the above-mentioned formula (1) measured at 30 ° C. in a 1 mol / l aqueous sodium chloride solution. ) Is the limiting viscosity number [η],
It is usually 2 or more, and preferably 3 or more from the viewpoint of performance.

The proportion of the sludge dewatering agent of the present invention to the cationic polymer which can be used in combination with the above-mentioned branched polyvinyl imidazophosphate, which is a cationic polymer flocculant, is not particularly limited, but preferably the weight ratio of both is 90%. : 10 to 10:
90, more preferably 80:20 to 20:80.

The anionic polymer flocculant used in the sludge dewatering agent of the present invention includes, for example, polyacrylic acid, (meth) acrylic acid or an alkali metal salt thereof and (meth)
Vinyl sulfonic acids such as copolymers with acrylamide, hydrolysates of poly (meth) acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, styrenesulfonic acid, vinylsulfonic acid or salts thereof and (meth)
A copolymer of acrylic acid or an alkali metal salt thereof and (meth) acrylamide is exemplified.

The anionic polymer flocculant used in the sludge dewatering agent of the present invention contains at least 1 mol% of anionic monomer units in the molecule, preferably at least 5 mol%, particularly preferably at least 5 mol%. 10 mol% or more.

The anionic polymer flocculant used in the sludge dewatering agent of the present invention has an intrinsic viscosity number [η] in the above-mentioned formula (1) measured at 30 ° C. in a 1 mol / l aqueous solution of sodium chloride. It is usually 5 to 20, and preferably 10 to 15 from the viewpoint of performance and ease of handling. If it is less than 5, the performance as a sludge dewatering agent is insufficient, and if it is more than 20, the viscosity of the wastewater after being added to the wastewater becomes extremely viscous, making it difficult to handle.

In the sludge dewatering agent of the present invention, the ratio of the cationic polymer flocculant to the anionic polymer flocculant is not particularly limited, but preferably the weight ratio of both is 90:
10 to 10:90, more preferably 80:20 to 2
0:80, particularly preferably 80:20 to 40:60.

The method of using the sludge dewatering agent of the present invention is not particularly limited. For example, the cationic polymer flocculant and the anionic polymer flocculant of the present invention are separately added to water at predetermined concentrations. Dissolve and first add and mix an aqueous solution of a cationic polymer flocculant to the sludge to be treated, then add and mix an aqueous solution of an anionic polymer flocculant,
A method of dehydrating the formed floc, or dissolving the cationic polymer flocculant and the anionic polymer flocculant of the present invention in water without separating them to obtain an aqueous solution of a predetermined concentration, and adding and mixing the sludge to be treated. Then, a method of dewatering the formed floc is produced. In the latter case, an acidic substance can be used together if necessary.

Acidic substances which can be used in combination with the sludge dewatering agent of the present invention include hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, ammonium chloride, ammonium sulfate, paratoluenesulfonic acid, formic acid, sodium hydrogensulfate, oxalic acid, sodium hydrogencarbonate and sulfamine. Acids and the like can be mentioned, but solid acids such as sulfamic acid are preferred from the viewpoint of easy handling.

The sludge dewatering agent of the present invention can be used in combination with an amphoteric polymer flocculant having both a cationic group and an anionic group in the molecule, if necessary.

In the method for dewatering sludge of the present invention, if necessary, an inorganic coagulant such as a sulfate band, ferrous sulfate polyiron sulfate, ferric chloride, and polyaluminum chloride, calcium chloride, calcium sulfate, calcium carbonate, Pulp, surfactants, deodorants, defoamers and the like can be used in combination.

The sludge dewatering agent of the present invention is used for the purpose of coagulating and removing substances suspended in wastewater, and is particularly effective for organic sludge. The organic sludge mentioned here is
For example, raw sludge, surplus sludge, concentrated sludge, or a mixed sludge thereof generated in a sewage treatment plant, digested sludge in human waste treatment, sludge generated by activated sludge treatment of industrial wastewater other than sewage, and the like. A dewatered cake is obtained by subjecting the flocculated floc formed by the sludge dewatering agent of the present invention to a dewatering treatment using a dewatering device such as a belt press, a screw press, a filter press, and a super decanter.

The sludge dehydrating agent of the present invention is generally added to the sludge dewatering agent at a rate of 0.04 to the solid content of the slurry containing the sludge to be treated.
It is 1 to 5.0% by weight, preferably 0.1 to 1.2% by weight. In addition, it is preferable that the pH of the slurry containing the sludge to be treated is usually 3.5 to 8.0.

[0057]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. Regarding the cationic polymer flocculant contained in the sludge dewatering agent used in the examples and comparative examples of the present invention, the intrinsic viscosity [η] and the Huggins constant k ′ of polyvinyl imidazolic acid and its raw material, polyacrylonitrile, were determined. The intrinsic viscosity [η] of the anionic polymer flocculant was measured by the following method.

<Intrinsic viscosity number [η] of polyacrylonitrile and Huggins constant k ′> N, N- at 30 ° C.
Polyacrylonitrile to be measured is dissolved in dimethylformamide to prepare a polymer solution having a predetermined concentration, and a viscometer, for example, an Ubbelohde viscometer is used to measure the viscosity of the polymer solution and N, N-dimethylformamide which is a pure solvent. The specific viscosity η _sp is determined from the number of seconds of falling between the marked lines shown in FIG. Next, a predetermined amount of N, N-dimethylformamide was added to the polymer solution to dilute the solution, and for five types of polymer solutions having different dilution rates, the falling seconds between the marked lines indicated by the viscometers were used. Determine the specific viscosity η _sp . In the above formula (1), the horizontal axis represents each polymer concentration C, the vertical axis represents η _sp / C at each polymer concentration C, and a zero extrapolation of the linear polymer concentration C connecting the points. The intrinsic viscosity number [η] is determined from the value.
The value of the slope of the straight line at this time was k '[η] ² , and the Huggins constant k' was obtained using the previously obtained [η].

<Intrinsic viscosity number [η] of polyvinyl imidazophosphate and Huggins constant k '> 0.1 at 30 ° C.
A branched polyimidazoline to be measured is dissolved in an aqueous solution of sodium chloride at a concentration of 1 mol / l to prepare a polymer solution having a predetermined concentration, and a polymer solution and a pure solvent of 0.1% are prepared using a viscometer such as an Ubbelohde viscometer. The specific viscosity η _sp is determined from the number of seconds of the mol / l sodium chloride aqueous solution falling between the marked lines indicated by the viscometer. Next, a predetermined amount of a 0.1 mol / l aqueous sodium chloride solution was added to the polymer solution to dilute the solution, and the five types of polymer solutions having different dilution rates were dropped between the marked lines indicated by a viscometer. From the number of seconds, the specific viscosity η
_Ask for _sp . In the above formula (1), each polymer concentration C is plotted on the horizontal axis, and η _sp / at each polymer concentration C is plotted on the vertical axis.
C is taken, and the intrinsic viscosity number [η] is determined from a zero extrapolation value of the polymer concentration C on a straight line connecting each point. The value of the slope of the straight line at this time was k '[η] ² , and the Huggins constant k' was obtained using the previously obtained [η].

<Intrinsic Viscosity Number [η] of Anionic Polymer Coagulant> The anionic polymer coagulant to be measured is dissolved in a 1 mol / l aqueous sodium chloride solution at 30 ° C. to prepare a solution having a predetermined concentration. By using a viscometer, for example, an Ubbelohde viscometer, the number of drops between the solution and the 1 mol / l aqueous sodium chloride solution as a pure solvent between the marked lines indicated by the viscometer is calculated as follows:
Determine the specific viscosity η _sp . Next, a predetermined amount of a 1 mol / l aqueous solution of sodium chloride was added to the solution to dilute the solution, and the specific viscosity was determined for each of the five types of solutions having different dilution rates from the drop seconds between the marked lines indicated by the viscometer. Find η _sp . In the above equation (1), the horizontal axis represents each concentration C, the vertical axis represents η _sp / C at each concentration C, and the limiting viscosity number [ η].

Further, the infrared absorption spectrum and the chlorine content of the branched polyvinyl imidazophosphate obtained in Production Example were measured by the following methods.

<Infrared Absorption Spectra> Measured by a KBr method at room temperature under a nitrogen atmosphere using a Shimadzu Fourier transform infrared spectrophotometer (FTIR-8100M).

<Chlorine Content> A predetermined amount of polyvinyl imidazophosphate is burned in an oxygen atmosphere, and the generated gas is absorbed in hydrogen peroxide. Then, an aqueous solution having a predetermined concentration is prepared and measured by an ion chromatography method. .

<Performance Evaluation> The performance evaluation (floc diameter, filtrate amount after 60 seconds, water content of dewatered cake) of the obtained sludge dewatering agent was performed as follows.

Mixed raw sludge (solid concentration 2.
300 ml of 7% by weight (pH 4.5) was collected in a 500 ml glass beaker, and the cationic polymer flocculant prepared in the 0.3% by weight aqueous solution obtained in Production Examples 1 to 3 was added thereto. 15 ml was added, and the mixture was stirred and coagulated for 20 seconds at 200 rpm by a jar tester. Subsequently, 7 ml of an anionic polymer coagulant prepared in a 0.2% by weight aqueous solution was added to the same beaker, and further, 200 rpm using a jar tester. Stir at rotation speed for 20 seconds,
After aggregation, the floc diameter was measured visually. The coagulated sludge was naturally filtered using a polyester filter cloth (sugi twill weave) for 60 seconds, and the amount of the filtrate was measured. Then, the coagulated sludge was sandwiched between two identical polyester filter cloths, and dewatered by a belt press machine ( Filter cloth: cedar twill weave, filter cloth tension: 4.0
0 kg / cm). The obtained dehydrated cake is dried at 105 ° C. for 12 hours.
After drying under reduced pressure for a period of time, the water content of the dehydrated cake was calculated from the weight loss of the flocculated sludge before and after drying.

Production Example 1 10.0 g of polyacrylonitrile having an intrinsic viscosity [η] of 13.5 and a Huggins constant k ′ of 0.41 measured in N, N-dimethylformamide at 30 ° C., and 100.0 g of ethylenediamine , 12.0 g of ammonium chloride,
After the flask was charged with 80.0 g of 1-butanol and purged with nitrogen, the internal temperature was raised to 95 ° C. while stirring. After stirring at 95 ° C. for 4.5 hours under stirring, the mixture was cooled, a viscous reaction solution was taken out, poured into acetone, further washed with acetone several times, and dried under reduced pressure to obtain a solid product of a reaction product of polyacrylonitrile and ethylenediamine. Was obtained in an amount of 22.9 g. Further, 5.0 g of the obtained solid was added to 300 ml of a methyl alcohol solution containing 10% by weight of hydrochloric acid, stirred and mixed at room temperature for 1 hour, the mixture was poured into acetone, further washed with acetone several times, and dried under reduced pressure. As a result, 4.5 g of a white solid was obtained. The obtained solid is a polyvinylimidazoline hydrochloride represented by the aforementioned chemical formula (1) due to its infrared absorption spectrum and chlorine content. Huggin measured
It was a polyvinylimidazoline hydrochloride having an s constant k ′ of 0.41 and an intrinsic viscosity [η] of 8.0.

Production Example 2 Instead of the polyacrylonitrile used in Production Example 1,
Same as Production Example 1 except that 10.0 g of polyacrylonitrile having an intrinsic viscosity [η] of 6.5 and a Huggins constant k ′ of 0.30 measured in N, N-dimethylformamide at 30 ° C. was used. The operation was performed to obtain 19.1 g of a solid product of a reaction product of polyacrylonitrile and ethylenediamine. Example 1 was further performed using 5.0 g of the obtained solid and 300 ml of a methyl alcohol solution containing 10% by weight of hydrochloric acid.
The same operation as described above was performed to obtain 4.8 g of a white solid. The obtained solid is a polyvinylimidazoline hydrochloride represented by the aforementioned chemical formula (1) due to its infrared absorption spectrum and chlorine content. It was a polyvinyl imidazoline hydrochloride having a measured Huggins constant k 'of 0.25 and an intrinsic viscosity [η] of 4.4.

Production Example 3 Instead of the polyacrylonitrile used in Production Example 1,
Same as Production Example 1 except that 10.0 g of polyacrylonitrile having an intrinsic viscosity [η] of 1.5 and a Huggins constant k ′ of 0.32 measured at 30 ° C. in N, N-dimethylformamide was used. The operation was performed to obtain 17.9 g of a reaction product of polyacrylonitrile and ethylenediamine. Example 1 was further performed using 5.0 g of the obtained solid and 300 ml of a methyl alcohol solution containing 10% by weight of hydrochloric acid.
The same operation as described above was performed to obtain 4.8 g of a white solid. The obtained solid is a polyvinylimidazoline hydrochloride represented by the aforementioned chemical formula (1) due to its infrared absorption spectrum and chlorine content. It was a polyvinyl imidazoline hydrochloride having a measured Huggins constant k 'of 0.35 and an intrinsic viscosity [η] of 1.5.

Example 1 In a 0.3% by weight aqueous solution of the polyvinylimidazoline hydrochloride obtained in Production Example 1 and a 1 mol / l aqueous sodium chloride solution, the intrinsic viscosity number [η] measured at 30 ° C. was 18.1.
A 0.2% by weight aqueous solution of the polyacrylamide partially hydrolyzed was prepared, and its performance was evaluated (floc diameter, amount of filtrate after 60 seconds, water content of dehydrated cake), and the results are shown in Table 1.

[0070]

[Table 1]

Example 2 The same operation as in Example 1 was carried out except that the polyvinyl imidazoline hydrochloride obtained in Production Example 2 was used, and the performance was evaluated (floc diameter, amount of filtrate after 60 seconds, water content of dehydrated cake). ) And the results are shown in Table 1.

Comparative Example 1 The same operation as in Example 1 was carried out except that the polyvinyl imidazoline hydrochloride obtained in Production Example 3 was used, and the performance was evaluated (floc diameter, amount of filtrate after 60 seconds, water content of dehydrated cake). ) And the results are shown in Table 1.

Comparative Example 2 A 0.3% by weight aqueous solution of the polyvinyl imidazoline hydrochloride obtained in Production Example 1 was prepared, and its performance was evaluated using only a cationic polymer flocculant (floc diameter, filtrate after 60 seconds). Amount and water content of the dehydrated cake), and the results are shown in Table 1.

Comparative Example 3 A 0.3% by weight aqueous solution of the polyvinyl imidazoline hydrochloride obtained in Production Example 2 was prepared, and its performance was evaluated using only a cationic polymer flocculant (floc diameter, filtrate after 60 seconds). Amount and water content of the dehydrated cake), and the results are shown in Table 1.

[0075]

As described above, by using the sludge dewatering agent of the present invention, coarse flocs can be formed and the water content of the dewatered cake can be reduced.

[Brief description of the drawings]

FIG. 1 is an infrared absorption spectrum of a solid obtained in Example 1.

Claims (1)

[Claims] 1. A sludge dewatering agent comprising a cationic polymer flocculant and an anionic polymer flocculant, wherein said cationic polymer flocculant is a polyvinyl imidazophosphate represented by the following chemical formula (1): The Huggins constant k ′ in the following formula (1) measured at 30 ° C. in a 0.1 mol / l aqueous sodium chloride solution is 0.2 to 0.5, and the intrinsic viscosity [η] is 2 to 15. A sludge dewatering agent, which is a cationic polymer flocculant comprising a branched polyvinyl imidazophosphate, characterized by the following: Embedded image (In the formula, X ⁻ represents a chloride anion, a sulfate anion, a carbonate anion, an anion of paratoluenesulfonic acid, an anion of formic acid, an anion of acetic acid, or an anion of propionic acid.) ] (Where η _sp is the specific viscosity, C is the polymer concentration, [η] is the limiting viscosity number, and k ′ is the Huggins constant.)