JPWO2020027312A1 - Method of dehydrating polymer flocculants and sludge - Google Patents

Abstract

It shows excellent dewatering performance even for difficult-to-dehydrate sludge, eliminates the drawbacks of transportation costs, and is a high-performance powder that can be used in existing equipment such as a general-purpose automatic melting device for powder that has been widely used in the past. It is to provide a polymer flocculant. In particular, it is an object of the present invention to provide an excellent polymer flocculant that can be dehydrated with a small amount of addition in addition to exhibiting excellent dehydration performance for difficult-to-dehydrate sludge. All of the above problems can be solved by a powdery polymer flocculant containing a water-soluble polymer (A) exhibiting specific solution physical characteristics and a water-soluble polymer (B) exhibiting different solution physical characteristics. That is, the powdered polymer flocculant of the present invention exhibits excellent dehydration performance, eliminates the drawbacks of transportation costs, and is used in existing equipment such as a general-purpose automatic melting device for powdered products that has been widely used in the past. Can be used.

Description

The present invention relates to a polymer flocculant and a method for dehydrating sludge. More specifically, the present invention provides a high-performance powdery polymer flocculant capable of effectively dehydrating refractory sludge and a dehydrated cake having a low water content, and dehydration of sludge using the same. Regarding the method.

Polymer coagulants are used for the purpose of coagulating, sedimenting, and separating suspensions contained in domestic wastewater, industrial wastewater, etc., as yield improvers in the papermaking industry, admixtures and mudicides in civil engineering and construction, etc. It is used. The polymer flocculant has nonionic, anionic, cation, and amphoteric ionic properties, but which ionic agent is used depends on the properties of the water to be treated and the treatment method.

Of these, cationic polymer flocculants are used for the purpose of flocculating and dehydrating excess sludge after treated with activated sludge in industrial and domestic wastewater, or as a yield improver in the paper industry. There are many. For sludge that is difficult to dehydrate in the former, a polymer having branching or cross-linking is used. In addition, the amphoteric polymer flocculant is used to coarsely floculate suspended particles charged and neutralized with a coagulant, and is used for sludge that is difficult to dehydrate or aggregate.

On the other hand, polymer flocculants have conventionally been in product forms such as powders and water-in-oil emulsions. Of these, the water-in-oil emulsion has the advantages of excellent solubility and uniform dissolution in a short time, but it is transported because it is more expensive to manufacture than powder and the content of the active ingredient of the polymer flocculant is low. There was a drawback that the cost was high.

Under such circumstances, recently, a cationic or amphoteric water-in-oil emulsion polymer having branching or cross-linking has been dried into a powder product, which exhibits excellent dehydration performance even for difficult-to-dehydrate sludge, and transportation cost. A high-performance powdery polymer flocculant that can be used in existing equipment such as a general-purpose automatic dissolving device for powder, which has been widely used in the past, has been developed.

For example, Patent Document 1 states that at least 90% by weight has a particle size of 10 μm or less by reverse-phase polymerization of a water-soluble monomer mixture containing a cationic monomer and 5 to 2000 ppm of a cross-linking agent in a non-aqueous liquid. A method for producing spray-dried granules and a powder obtained. The use of the product as a polymer flocculant is disclosed.

However, the spray-dried granules of the crosslinked polymer described in Patent Document 1 show better performance by improving the filtrate volume (filterability) at the optimum addition amount as compared with the linear polymer, but have a high polymer dose ( Addition amount) is required. There is no description of measures to reduce the amount added.

Patent Document 2 describes a vinyl polymerization-based crosslinkable water-soluble ionic polymer (A) having a charge inclusion rate of 20% or more, which corresponds to the mass% of 200 mesh-on particles in the sludge with respect to the total suspended particles in the sludge. And, a flocculant composition characterized by changing the composition of the vinyl polymerization type linear water-soluble ionic polymer (B) having a charge inclusion rate of 5% or more and less than 20% is disclosed.

However, Patent Document 2 is not sufficiently satisfactory in terms of excellent dehydration performance and reduction of the amount of polymer added by utilizing different combinations of surface charges of polymer particles in a solution, although some effects can be seen. There wasn't. In particular, since the state of surface charge differs depending on the type and composition ratio of the cationic monomer used, it is not always a preferable combination of polymer physical properties, and it is insufficient to exhibit excellent dehydration performance for difficult-to-dehydrate sludge. Further, Patent Document 2 describes only a water-in-oil emulsion and a dispersion in salt water as product forms, and does not substantially cover powdered products, and mentions elimination of the drawback of transportation cost. It has not been.

The applicant has so far developed a sludge dehydrating agent consisting of a mixture of a cationic polymer having a specific solution viscosity and a specific amphoteric polymer (Patent Document 3). When the sludge dewatering agent of the present invention is used, a larger sludge cohesive floc and a higher amount of drainage can be obtained with a smaller addition amount even for difficult-to-dehydrate sludge and difficult-to-dehydrate conditions, and the obtained cake water content is also remarkable. It is reduced and good processing is possible. This sludge dewatering agent shows excellent dewatering performance. Even in this technology, there is no example of powdered products, and powdered products are not practically targeted, and there is room for consideration in terms of transportation costs.

Patent No. 4043517 Patent No. 5103395 Patent No. 4201419

The subject of the present invention is that it exhibits excellent dewatering performance even for difficult-to-dehydrate sludge, eliminates the drawback of transportation cost, and is used in existing equipment such as a general-purpose automatic melting device for powder that has been widely used in the past. It is to provide a high-performance powdery polymer flocculant that can be produced. In particular, it is an object of the present invention to provide an excellent polymer flocculant that can be dehydrated with a small amount of addition in addition to exhibiting excellent dehydration performance for difficult-to-dehydrate sludge.

As a result of diligent studies, the present inventors have conducted a powdery polymer aggregation containing a water-soluble polymer (A) exhibiting a specific solution physical characteristic and a water-soluble polymer (B) exhibiting a different solution physical characteristic. We have found that the agent can solve all of the above problems. That is, the powdered polymer flocculant of the present invention exhibits excellent dehydration performance, eliminates the drawbacks of transportation costs, and is used in existing equipment such as a general-purpose automatic melting device for powdered products that has been widely used in the past. After confirming that it can be used, the present invention was completed.

That is, the present invention
[1] At least the water-soluble polymer (A) having a solution viscosity ratio of 900 or more and less than 10,000 represented by the following formula (1) and the water-soluble weight having a solution viscosity ratio of 100 or more and less than 900. It contains the coalescence (B), and the content of the water-soluble polymer (A) is 5 to 90% by mass with respect to the total mass of the water-soluble polymer (A) and the water-soluble polymer (B). It is a powdery cationic or amphoteric polymer flocculant.

However, the viscosity of the 0.5% aqueous solution is the viscosity (mPa · s) measured by using a B-type rotary viscometer at a rotor rotation speed of 12 rpm and 25 ° C. for a polymer aqueous solution having a concentration of 0.5% by mass. For the 0.1% salt viscosity, a 0.5% by mass concentration polymer aqueous solution was diluted to a 0.1% by mass concentration, and a 1N NaCl-dissolved polymer salt aqueous solution was used as a B-type rotary viscometer and a BL adapter. Is the viscosity (mPa · s) measured at a rotor rotation speed of 60 rpm and 25 ° C.

[2] The powder according to the above [1], wherein the water-soluble polymers (A) and (B) contain one or more cationic constituent units having a structure represented by the following general formula (2). It is a polymer flocculant.

However, R ¹ is a hydrogen atom or a methyl group, R ² and R ³ are independently alkyl groups or benzyl groups ^{having 1 to 3 carbon atoms, and R 4} is a hydrogen atom or an alkyl group or benzyl group having 1 to 3 carbon atoms. Yes, it may be of the same type or different types. X represents 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.

[3] The water-soluble polymers (A) and (B) are at least one of a methyl chloride quaternary salt or a benzyl chloride quaternary salt of dimethylaminoethyl acrylate and a methyl chloride quaternary salt of dimethylaminoethyl methacrylate. The powdery polymer flocculant according to the above [1] or [2], which is obtained by polymerizing a monomer mixture containing seeds.

[4] The powder form according to the above [3], wherein the water-soluble polymer (A) and / or (B) is obtained by further polymerizing a monomer mixture containing a nonionic monomer. It is a polymer flocculant of.

[5] The powdery polymer flocculant according to the above [4], wherein the nonionic monomer is acrylamide.

[6] In the above [4] or [5], the water-soluble polymer (A) and / or (B) is obtained by further polymerizing a monomer mixture containing an anionic monomer. The powdery polymer flocculant according to the above.

[7] The powdery polymer flocculant according to the above [6], wherein the anionic monomer is acrylic acid.

[8] The water-soluble polymers (A) and (B) are both ^{powders having a bulk specific gravity of 0.5 to 0.8 g / cm 3} , and at least one of the powders has a particle strength of 5 N or more. The powdery polymer according to any one of the above [1] to [7], which is a powder containing a granulated product that has been granulated so as to be, and is a mixture of two or more kinds of the powder. It is a flocculant.

[9] A method for dehydrating sludge by adding at least one of the polymer flocculants according to any one of the above [1] to [8] to sludge.

[10] The 0.5% aqueous solution viscosity of the water-soluble polymer (A) is 1,000 to 15,000 mPa · s, and the 0.1% salt viscosity of the water-soluble polymer (A) is 1.1. ~ 3.5 mPa · s, the 0.5% aqueous solution viscosity of the water-soluble polymer (B) is 500 to 3,500 mPa · s, and the 0.1% salt viscosity of the water-soluble polymer (B). The powdery polymer flocculant according to any one of the above [1] to [8], wherein is 1.8 to 7.0 mPa · s.

[11] The method for producing a powdery polymer flocculant according to any one of the above [1] to [8], wherein the powdery water-soluble polymer (A) is prepared by reverse phase emulsion polymerization. This is a method for producing a powdery polymer flocculant by preparing the powdery water-soluble polymer (B) by aqueous polymerization and mixing the two.

The polymer flocculant obtained in the present invention not only exhibits excellent dewatering performance for difficult-to-dehydrate sludge, but also eliminates the drawback of transportation cost, and is an automatic powder for general-purpose powder that has been widely used in the past. It can also be used in existing equipment such as melting equipment. In particular, it is possible to highly balance the contradictory performance of exhibiting excellent dewatering performance for difficult-to-dehydrate sludge and the ability to perform dewatering treatment with a small amount of addition. It is possible to provide such a high-performance powdery polymer flocculant.

Further, the polymer coagulant of the present invention is used as a coagulation / dehydrating agent for domestic wastewater and industrial wastewater sludge, such as a draining fluid retention improver for papermaking, a drainage improver, a formation aid, and a paper strength enhancer. It can be applied to a wide range of applications such as paper chemicals, coagulants for drilling / muddy water treatment, additives for increasing crude oil production, organic coagulants, thickeners, dispersants, antiscale agents, antistatic agents and processing agents for textiles. It is possible.

The present invention will be described in detail below.
In the present specification, acrylate and / or methacrylate is referred to as (meth) acrylate, acrylamide and / or methacrylamide is referred to as (meth) acrylamide, and acrylic acid and / or methacrylic acid is referred to as (meth) acrylic acid. Also, an acid and its salt are referred to as an acid (salt).

The polymer flocculant of the present invention exhibits excellent dehydration performance for difficult-to-dehydrate sludge, and is water-soluble, which exhibits specific solution physical characteristics in order to realize excellent performance that allows dehydration treatment with a small amount of addition. It contains a polymer (A) and a water-soluble polymer (B) having different solution physical characteristics.

In the present invention, the solution viscosity ratio represented by the following formula (1) is used to specify the water-soluble polymer (A) and the water-soluble polymer (B).

However, the viscosity of the 0.5% aqueous solution is the viscosity (mPa · s) measured by using a B-type rotary viscometer at a rotor rotation speed of 12 rpm and 25 ° C. for a polymer aqueous solution having a concentration of 0.5% by mass. For the 0.1% salt viscosity, a 0.5% by mass concentration polymer aqueous solution was diluted to a 0.1% by mass concentration, and a 1N NaCl-dissolved polymer salt aqueous solution was used as a B-type rotary viscometer and a BL adapter. Is the viscosity (mPa · s) measured at a rotor rotation speed of 60 rpm and 25 ° C.

The solution viscosity ratio is usually a positive number of 1 or more, and the larger the value, the larger the amount of non-linear structure introduced into the water-soluble polymer such as branching and cross-linking, and the smaller the value, the more water-soluble. This means that the amount of the non-linear structure introduced into the sex polymer is small and the linearity is high. In the present specification, the difference in the introduction amount of the non-linear structure represented by the solution viscosity ratio may be expressed as "crosslinking degree".

The solution viscosity ratio of the water-soluble polymer (A) of the present invention is 900 or more and 10,000 or less. If the solution viscosity ratio exceeds 10,000, the degree of cross-linking is too high, and aggregation does not occur unless the amount added is increased several times to several tens of times as compared with a normal linear polymer flocculant, which is economical. It is not realistic from the point of view. On the other hand, when the solution viscosity ratio is less than 900, the degree of cross-linking is too low, and excellent dehydration performance cannot be exhibited for difficult-to-dehydrate sludge. The solution viscosity ratio of the water-soluble polymer (A) is preferably 950 or more and 5,000 or less, and most preferably 1,000 or more and 3,500 or less.

The viscosity of the 0.5% aqueous solution of the water-soluble polymer (A) of the present invention is preferably 1,000 to 15,000 mPa · s. If the viscosity of the 0.5% aqueous solution exceeds 15,000 mPa · s, the degree of cross-linking is too high, and aggregation must be increased several times to several tens of times as much as that of a normal linear polymer flocculant. Since it does not, it may not be realistic from an economic point of view. On the other hand, if the viscosity of the 0.5% aqueous solution is less than 1,000 mPa · s, the degree of cross-linking is too low or the molecular weight is too low, and excellent dehydration performance may not be exhibited for difficult-to-dehydrate sludge. The viscosity of the water-soluble polymer (A) in a 0.5% aqueous solution is more preferably 1,500 to 10,000 mPa · s, and most preferably 2,000 to 6,000 mPa · s.

The 0.1% salt viscosity of the water-soluble polymer (A) of the present invention is preferably 1.1 to 3.5 mPa · s. If the 0.1% salt viscosity is less than 1.1 mPa · s, the degree of cross-linking is too high, and aggregation does not occur unless the amount added is increased several to several tens of times as compared with a normal linear polymer flocculant. Therefore, it may not be realistic from an economic point of view. On the other hand, if the 0.1% salt viscosity exceeds 3.5 mPa · s, the degree of cross-linking may be too low to exhibit excellent dewatering performance for difficult-to-dehydrate sludge. The 0.1% salt viscosity of the water-soluble polymer (A) is more preferably 1.2 to 3.0 mPa · s, and most preferably 1.4 to 2.5 mPa · s.

In the water-soluble polymer (A) of the present invention, the viscosity of a 0.5% aqueous solution is 1,000 to 15,000 mPa · s, and the viscosity of 0.1% salt is 1.1 to 3.5 mPa · s. Is preferable.

The solution viscosity ratio of the water-soluble polymer (B) of the present invention is 100 or more and less than 900. When the solution viscosity ratio is 900 or more, the linearity is insufficient, and even when used in combination with the water-soluble polymer (A), it exhibits excellent dewatering performance for difficult-to-dehydrate sludge and is added in a small amount. It is not possible to highly balance the contradictory performance of being able to dehydrate by quantity. On the other hand, when the solution viscosity ratio is less than 100, the molecular weight and ionicity are too low to realize sufficient performance as a polymer flocculant. The solution viscosity ratio of the water-soluble polymer (B) is preferably 150 or more and 850 or less, and most preferably 200 or more and 800 or less.

The viscosity of the 0.5% aqueous solution of the water-soluble polymer (B) of the present invention is preferably 500 to 3,500 mPa · s. When the viscosity of the 0.5% aqueous solution exceeds 3,500 mPa · s, the linearity is insufficient, and even when used in combination with the water-soluble polymer (A), it exhibits excellent dewatering performance against difficult-to-dehydrate sludge. In some cases, it is not possible to highly balance the contradictory performance of being able to perform dehydration treatment with a small amount of addition. On the other hand, if the viscosity of the 0.5% aqueous solution is less than 500 mPa · s, the molecular weight and ionicity may be too low to realize sufficient performance as a polymer flocculant. The viscosity of the 0.5% aqueous solution of the water-soluble polymer (B) is more preferably 700 to 3,000 mPa · s, and most preferably 900 to 2,500 mPa · s.

The 0.1% salt viscosity of the water-soluble polymer (B) of the present invention is preferably 1.8 to 7.0 mPa · s. If the 0.1% salt viscosity exceeds 7.0 mPa · s, the linearity may be insufficient, and even when used in combination with the water-soluble polymer (A), it is excellently dehydrated against difficult-to-dehydrate sludge. It may not be possible to highly balance the contradictory performances of exhibiting performance and dehydration treatment with a small amount of addition. On the other hand, if the 0.1% salt viscosity is less than 1.8 mPa · s, the molecular weight and ionicity may be too low to realize sufficient performance as a polymer flocculant. The 0.1% salt viscosity of the water-soluble polymer (B) is more preferably 2.0 to 5.6 mPa · s, and most preferably 2.2 to 3.9 mPa · s.

In the water-soluble polymer (B) of the present invention, the viscosity of the 0.5% aqueous solution is preferably 500 to 3,500 mPa · s, and the viscosity of the 0.1% salt is preferably 1.8 to 7.0 mPa · s. ..

In the present invention, the content of the water-soluble polymer (A) is 5 to 90% by mass with respect to the total mass of the water-soluble polymer (A) and the water-soluble polymer (B). If the content of the water-soluble polymer (A) exceeds 90% by mass, the performance of the water-soluble polymer (A) is too strong and the water-soluble polymer (A) does not aggregate unless the amount added is increased, which is not preferable from an economical point of view. If the content of the water-soluble polymer (A) is less than 5% by mass, the performance of the water-soluble polymer (B) is too strong, and excellent dehydration performance cannot be exhibited for difficult-to-dehydrate sludge. The content of the water-soluble polymer (A) is preferably 10 to 80% by mass, and most preferably 10 to 70% by mass.

In the present invention, the content of the water-soluble polymer (B) with respect to the total mass of the water-soluble polymer (A) and the water-soluble polymer (B) is 10 to 95% by mass. If the content of the water-soluble polymer (B) exceeds 95% by mass, the performance of the water-soluble polymer (B) is too strong, and excellent dehydration performance cannot be exhibited for difficult-to-dehydrate sludge. If the content of the water-soluble polymer (B) is less than 10% by mass, the performance of the water-soluble polymer (A) is too strong and the water-soluble polymer (A) does not aggregate unless the amount added is increased, which is not preferable from an economical point of view. The content of the water-soluble polymer (B) is preferably 20 to 90% by mass, and most preferably 30 to 90% by mass.

The water-soluble polymers (A) and (B) of the present invention are cationic or amphoteric water-soluble polymers, and can be obtained by radical polymerization of a monomer mixture containing a cationic monomer as an essential component. can. In addition to the cationic monomer, the monomer mixture may contain other monomers copolymerizable with the cationic monomer, if necessary. Further, the water-soluble polymers (A) and (B) preferably contain one or more cationic constituent units having a structure represented by the following general formula (2).

However, R ¹ is a hydrogen atom or a methyl group, R ² and R ³ are independently alkyl groups or benzyl groups ^{having 1 to 3 carbon atoms, and R 4} is a hydrogen atom or an alkyl group or benzyl group having 1 to 3 carbon atoms. Yes, it may be of the same type or different types. X represents 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.

The cationic monomer that can be used in the present invention may be any monomer having a radically polymerizable double bond and a cationic group capable of radical polymerization, and the compound represented by the following general formula (3). In addition, diallyldialkylammonium halides such as diallyldimethylammonium chloride can be mentioned. Among these cationic monomers, it is excellent in radical polymerization reactivity, easy to increase the molecular weight required as a polymer flocculant, and excellent performance of the obtained polymer as a polymer flocculant. The compound represented by the following general formula (3) is preferable.

However, R ¹ is a hydrogen atom or a methyl group, R ² and R ³ are independently alkyl groups or benzyl groups ^{having 1 to 3 carbon atoms, and R 4} is a hydrogen atom or an alkyl group or benzyl group having 1 to 3 carbon atoms. Yes, it may be of the same type or different types. X represents 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, Z ⁻ represents a counter anion, and Z ⁻ represents a halide ion such as a chloride ion. And sulfate ion are exemplified.

Specific examples of the cationic monomer represented by the general formula (3) include dialkyls such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, and dimethylamino-2-hydroxypropyl (meth) acrylate. Examples thereof include hydrochlorides and sulfates of aminoalkyl (meth) acrylates, alkyl halide adducts such as methyl chloride, benzyl halide adducts such as benzyl chloride, and dialkyl adducts sulfate such as dimethyl sulfate. Will be done. In addition, dialkylaminoalkyl (meth) acrylamide hydrochloride and sulfate such as dimethylaminopropyl (meth) acrylamide, alkyl halide adduct such as methyl chloride, benzyl halide adduct such as benzyl chloride, and sulfuric acid such as dimethyl sulfate. A quaternary salt such as a dialkyl adduct is also exemplified.

Among these preferable cationic monomers, a quaternary salt which is a methyl chloride adduct of dimethylaminoethyl acrylate and a methyl adduct of dimethylaminoethyl methacrylate, which are particularly easy to increase the molecular weight required for a polymer flocculant. The quaternary salt is most preferable. A quaternary salt, which is a benzyl chloride adduct of dimethylaminoethyl acrylate, is preferable for treating sludge having a high salt concentration (high electrical conductivity) discharged from livestock farms and the like. These cationic monomers may be used alone or in combination of two or more.

In the present invention, any monomer copolymerizable with the cationic monomer can be used without particular limitation. Of these, nonionic monomers and anionic monomers are exemplified below.

Nonionic monomers include (meth) acrylamide compounds, (meth) methyl acrylate, (meth) ethyl acrylate, (meth) butyl acrylate, (meth) hydroxyethyl acrylate, and the like. Examples thereof include alkyl acrylate, styrene, acrylonitrile, vinyl acetate and the like. Among these nonionic monomers, (meth) acrylamide is preferable, water-soluble, and highly high because it is easy to increase the molecular weight required as a polymer flocculant and the performance as a polymer flocculant is excellent. Acrylamide, which has particularly excellent performance as a molecular flocculant, is most preferable. These nonionic monomers may be used alone or in combination of two or more.

Examples of the anionic monomer include (meth) acrylic acid and salts thereof, vinyl sulfonic acid, 2-acrylamide-2-methylpropanesulfonic acid, maleic acid and the like, and salts thereof. Among these anionic monomers, (meth) acrylic acid and salts thereof are preferable because it is easy to increase the molecular weight required as a polymer flocculant and the performance as a polymer flocculant is excellent. As the salts, ammonium salts and alkali metal salts such as sodium salts and potassium salts are preferable. These anionic monomers may be used alone or in combination of two or more.

The compounding ratio (molar ratio) of each monomer in the monomer mixture is not particularly limited. The compounding ratio (molar ratio) of each monomer in the monomer mixture is cationic monomer: anionic monomer: nonionic monomer = 1 to 100: 0 to 99: 0 to 99. .. When a nonionic monomer is used, the content of the nonionic monomer in the monomer mixture is preferably 3 to 98 mol%, particularly preferably 5 to 95 mol%.

Crosslinkable monomers are used for the purpose of introducing branched or crosslinked structures into polymer chains. As the crosslinkable monomer, methylenebisacrylamide or di (meth) acrylate represented by the following formula (4) is preferable, and in the latter, di (meth) acrylate to which highly water-soluble polyethylene glycol and / or polypropylene glycol is added is preferable. preferable. Among these, methylenebisacrylamide having a small molecular weight, water solubility, and high reactivity is particularly preferable.

However, R ⁵ and R ⁶ are independently H or CH ₃ , Y is O (C ₂ H ₄ O) _n or O (C ₃ H ₆ O) _n , and n is an integer of 1 to 10.

The preferable amount of the crosslinkable monomer added varies depending on the type of the crosslinkable monomer used, the molecular weight and the reactivity, but generally, 1 to 1,000 ppm is preferable with respect to the total mass of the total monomer mixture. , 1 to 500 ppm is more preferable, and 1 to 200 ppm is most preferable. If it is added in excess of 1,000 ppm, the degree of cross-linking is too high, and the agglutinating performance as a polymer flocculant is significantly reduced.

The polymerization method for obtaining the water-soluble polymers (A) and (B) of the present invention is not particularly limited, but specific forms of radical polymerization applicable to the present invention include aqueous polymerization and reverse phase suspension. Examples thereof include polymerization and reverse phase emulsion polymerization. Among these, for the water-soluble polymer (A), the primary particle diameter (median diameter) of the water-soluble polymer can be easily adjusted to 10 μm or less, and the solution viscosity ratio can be easily adjusted to 900 or more and 10,000 or less. Application of reverse phase emulsion polymerization is preferred. On the other hand, for the water-soluble polymer (B), it is preferable to apply aqueous solution polymerization in which the solution viscosity ratio can be easily adjusted to 100 or more and less than 900, which is advantageous in terms of production cost in industrial production.

In the present invention, when producing a powdery polymer flocculant, the powdery water-soluble polymer (A) is prepared by reverse phase emulsion polymerization, and the powdery water-soluble polymer (B) is prepared by aqueous solution polymerization. ), And a method for producing a powdery polymer flocculant by mixing the two is preferable.

(1) Application example of reverse phase emulsion polymerization When reverse phase emulsion polymerization is applied, hydrocarbons that are substantially immiscible with water are generally used for the continuous phase. In the polymer flocculant of the present invention, it is necessary to carry out emulsion polymerization, reflux dehydration if necessary, and then dry the continuous phase hydrocarbons for pulverization. Therefore, hydrocarbons having a very high boiling point are not preferable, and hydrocarbons having a boiling point at normal pressure in the range of 65 to 130 ° C. are preferable. Specifically, normal heptane is preferable.

In the polymer flocculant of the present invention, a nonionic surfactant having an HLB of 3.0 to 9.0 is preferably used as the surfactant for reverse phase emulsion polymerization. Nonionic surfactants with an HLB of 3.0 to 5.0 are even more preferred.

Examples of surfactants are polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene alkyl ether, polyoxyethyl alkylene alkyl ether, sorbitan monoolate, sorbitan sesquiolate, sorbitan monolaure. Rate, Polyoxyethylene sorbitan monolaurate, Polyoxyethylene sorbitan triolate, Polyoxyethylene sorbit tetraoleate, Polyethylene glycol monoolate, Polyethylene glycol dioleate, Diethanolamide oleate, Monoethanolamide laurate, Monostearate Nonionic surfactants such as ethanolamide can be mentioned.
The effective addition amount of these surfactants is preferably 0.25 to 15% by mass, more preferably 0.5 to 10% by mass, based on the total amount of the water-in-oil emulsion.

The polymerization conditions are appropriately set according to the monomer used, the initiator, and the physical properties of the polymer. The polymerization temperature is 0 to 100 ° C., preferably 10 to 80 ° C. The monomer concentration is preferably 20 to 50% by mass, more preferably 25 to 45% by mass. The polymerization time is preferably 1 to 10 hours.

Examples of the polymerization initiator include persulfates such as sodium persulfate and potassium persulfate, organic peroxides such as benzoyl peroxide, t-butyl hydroperoxide, and paramentan hydroperoxide, and 2,2'-azobis (2). -Methylpropionamidine) dihydrochloride, 4,4'-azobis (4-cyanovaleric acid), 2,2'-azobisisobutyronitrile and 2,2'-azobis [2-methyl-N- (2) -Hydroxyethyl) -propionamide] and other azo compounds, as well as known redox-based initiators consisting of a combination of an oxidizing agent such as hydrogen peroxide and persulfate and a reducing agent such as sodium sulfite and ferrous sulfate. Can be mentioned. These polymerization initiators may be used alone or in combination of two or more.

As a method for adjusting the molecular weight, a known chain transfer agent can be used. Known chain transfer agents include thiol compounds such as mercaptoethanol and mercaptopropionic acid, reducing inorganic salts such as sodium sulfite, sodium hydrogen sulfite and sodium hypophosphate, alcohols such as ethanol and isopropyl alcohol, and metallicyl. Examples thereof include (meth) allyl compounds such as sodium sulfite.

In addition, additives such as stabilizers, pH adjusters, and antioxidants may be added as long as the effects of the present invention are not impaired.

When the water-soluble polymer (A) of the polymer flocculant of the present invention is obtained by reverse phase emulsion polymerization, the median diameter of the particle size distribution of the primary particles of the water-soluble polymer is adjusted to 0.3 to 10 μm. It is preferably 0.5 to 5 μm, more preferably 0.7 to 3 μm. If the median diameter exceeds 10 μm, the agglutinating performance of the polymer flocculant is significantly reduced. Even if the median diameter is made smaller than 0.3 μm, the performance of the polymer flocculant is not improved, and the process of increasing the amount of emulsifier and applying higher shear in the emulsifier becomes wasteful, which is not preferable. After adding the aqueous phase of the aqueous solution of the monomer mixture to the oil phase in which the surfactant is dissolved in the hydrocarbon so that the median diameter of the primary particles of the water-soluble polymer falls within the above range, it is emulsified using an emulsifier. It is preferable to keep it.

Further, before drying the water-soluble polymer of the water-in-oil emulsion obtained by reverse phase emulsion polymerization, it is preferable to remove the water content in the emulsion by reflux dehydration so that the emulsion is not destroyed. If the product is dried without reflux dehydration or with insufficient removal of water, the hydrocarbon will dry before the water content, depending on the boiling point of the hydrocarbon, and the hydrous polymer particles will fuse together and become huge. It becomes a hydrogel-like deposit. In that case, it becomes difficult to sufficiently dry the remaining water, or the hydrous polymer solidifies into a glass while adhering to the wall or bottom of the stirring tank or dryer, which makes it difficult to take it out and pulverize it.

After reflux dehydration, the powdery water-soluble polymer can be preferably obtained by drying the remaining water and hydrocarbons from the slurry in which the water-soluble polymer is dispersed.

Alternatively, as another method, the water-soluble polymer of the water-in-oil emulsion obtained by reverse phase emulsion polymerization is spray-dried without performing reflux dehydration or after removing a part of water by reflux dehydration. It can also be powdered. However, as described in the background technology, due to the characteristics of the spray dryer, it is necessary to dry little by little in a short time, so it is necessary to dry at a very high temperature, and the high molecular weight water-soluble polymer causes thermal deterioration. It is easy to receive, the quality may vary, or it may not be possible to adjust to the target solution viscosity ratio. In that case, it is necessary to suppress the thermal deterioration by lowering the drying temperature and further drying in small amounts.

When the polymer flocculant of the present invention is obtained by reverse phase emulsion polymerization, a powdery water-soluble polymer is obtained by the above operation, then wet stirring and granulation, and if necessary, drying, sieving, crushing, etc. It is preferable to adjust the powder characteristics so that it can be easily used as a polymer flocculant. As an example of the powder characteristics, the coarse particles having a particle size of more than 1.7 mm and the fine powder having a particle size of less than 180 μm are each preferably 10% by mass or less, more preferably 5% by mass or less. If there are many coarse particles, the dissolution rate when the polymer flocculant powder is dissolved in water becomes slow, which is not preferable. On the other hand, if there is a large amount of fine powder, it will be powdered, which will deteriorate the working environment of the person who handles the polymer flocculant, which is not preferable. The particle size component of 0.5 to 1.7 mm is preferably 50% by mass or more, more preferably 60% by mass or more, and most preferably 70% by mass or more. Preferably the bulk density is 0.5~0.8g / cm ^3, more preferably 0.6~0.7g / cm ^3.

Further, when the powdery water-soluble polymer is granulated, the particle strength of the granulated product is preferably 5 to 50 N, more preferably 10 to 40 N, and most preferably 15 to 30 N. If the particle strength is less than 5N and insufficient, some of the granulated particles may collapse and return to fine powder during transportation or use of the granulated product. On the other hand, a strength in which the particle strength exceeds 50 N is not preferable because the quality of the polymer flocculant is excessive and the cost is high.

(2) Application Example of Aqueous Solution Polymerization When applying aqueous solution polymerization, a method of aqueous solution polymerization of an aqueous solution of a monomer mixture containing at least a cationic monomer in the presence of a radical polymerization initiator is exemplified. The concentration of the monomer mixture is preferably 25 to 85% by mass, more preferably 30 to 65% by mass. The pH of the aqueous solution of the monomer mixture is preferably adjusted 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 compounds such as azobisisobutyronitrile, redox-based initiators and photopolymerization. Initiators and the like can be used as appropriate.

These radical polymerization initiators may be used alone or in combination of two or more.

The polymerization start temperature is usually preferably 0 to 35 ° C. The polymerization time is usually preferably 0.1 to 3 hours. Further, the polymerization reaction is preferably carried out in an inert atmosphere in which oxygen does not exist. These polymerization conditions are known. After the completion of the polymerization reaction, post-treatments such as heat treatment, drying, and pulverization are appropriately performed as necessary. Known methods can also be applied to these post-treatments.

Among the aqueous solution polymerizations, light irradiation polymerization is particularly preferable because the obtained water-soluble polymer has little variation in physical properties and quality, stable production is possible, and the physical properties can be easily adjusted. As a specific example of light irradiation polymerization, an aqueous solution of a monomer mixture containing at least a cationic monomer is polymerized by irradiating the aqueous solution of the monomer mixture with light in the presence of a photopolymerization initiator and a chain transfer agent. The method of performing the above is exemplified.

The photopolymerization initiator used for light irradiation polymerization is not particularly limited. Preferable photopolymerization initiators include acetophenone-based photopolymerization initiators and azo-based initiators. Among them, the monomer mixture has high solubility in an aqueous solution, and the high molecular weight required as a polymer flocculant can be obtained. A water-soluble azo-based initiator is particularly preferable because it is easy and the like.

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 amount of the photopolymerization initiator added is not particularly limited. It may be appropriately adjusted according to the type of the photopolymerization initiator, the molecular weight of the water-soluble polymer, the monomer composition and the content of the residual monomer. In the case of a water-soluble azo initiator, it is usually preferably 100 to 3,000 ppm by mass with respect to the total mass of each monomer in the monomer mixture.

The chain transfer agent used for light irradiation polymerization is mainly added for the purpose of adjusting the molecular weight of the water-soluble polymer and suppressing the generation of insoluble matter, but the type thereof is not particularly limited. Examples of the chain transfer agent that can be used in aqueous solution polymerization include sodium hydrogen sulfite, sodium sulfite, sodium hypophosphite, mercaptoethanol, isopropanol and the like. Among these, sodium bisulfite is preferable because it has high solubility in an aqueous solution of the monomer mixture, is highly effective even with a small amount of addition, and the molecular weight of the water-soluble polymer can be easily adjusted.

These chain transfer agents may be used alone or in combination of two or more.

The amount of the chain transfer agent added is not particularly limited. It may be appropriately adjusted according to the type of chain transfer agent, the molecular weight of the water-soluble polymer, the monomer composition, the amount of the crosslinkable monomer added and the amount of insolubility. In the case of sodium bisulfite, it is usually preferably 1 to 100 ppm on a mass basis with respect to the total mass of each monomer in the monomer mixture.

The light irradiation conditions such as the wavelength of light, the irradiation intensity, and the irradiation time used for the light irradiation polymerization are not particularly limited. It may be appropriately adjusted according to the type and amount of the photopolymerization initiator used and the physical properties and performance of the water-soluble polymer. When the water-soluble azo-based 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 1.0 mW / cm ² by a UV illuminance meter for 365 nm. The irradiation time is usually preferably 0.1 to 3 hours.

In the polymer flocculant of the present invention, for powdering, it is preferable that the hydrogel obtained after the aqueous solution polymerization is shredded to an appropriate size (preferably about 0.5 to 5 mm) and then dried. If necessary, it may be further pulverized into a powder, or granulated, sieved, or the like to adjust the powder characteristics so that it can be easily used as a polymer flocculant. The water-containing gel is generally preferably dried at 60 to 130 ° C. Preferred powder properties are the same as described above.

When the water-soluble polymer (B) of the polymer flocculant of the present invention is obtained by aqueous solution polymerization, the weight average molecular weight of the water-soluble polymer is preferably 1 million to 20 million. When the weight average molecular weight is less than 1 million, the ability to form sludge flocs as a polymer flocculant is insufficient, and the flocs diameter may not be sufficiently large. Further, if the weight average molecular weight exceeds 20 million, the cross-linking reaction may proceed too much, and in that case, the insoluble amount that is insoluble in water increases, and the amount of the active ingredient that effectively acts as a polymer flocculant increases. Not only is it reduced, but it may also cause troubles that block the pump at the site where the solution of the polymer flocculant dissolved in water is sent.

Sludge dewatering method In the sludge dewatering method in which at least one of the polymer flocculants of the present invention is added to dewater, the sludge to be treated is not particularly limited. In addition to sludge generated in sewage treatment, human waste treatment, domestic wastewater treatment, etc., sludge generated in various industrial wastewater treatments such as food factories, meat processing and chemical factories, raw urine generated in livestock farms such as pig farms and its wastewater Various sludges such as sludge generated in the treatment and sludge generated in the pulp or paper industry are treated. There are no restrictions on the type of sludge, and initial sludge, excess sludge, mixed sludge thereof, concentrated sludge, digested sludge treated with anaerobic microorganisms, etc. are all treated.

The sludge dehydration method of the present invention is characterized in that at least one of the polymer flocculants of the present invention is added to the various sludges to dehydrate the sludge.

The following methods are exemplified as specific examples of the dehydration method. That is, an inorganic flocculant is added to the sludge as needed, and the pH is preferably adjusted to 4 to 7. Then, the polymer flocculant of the present invention is added to the sludge, and the suspension in the sludge and the polymer flocculant are allowed to act by stirring and / or mixing by a known method to form sludge flocs. The formed sludge flocs are mechanically dehydrated by a known means to separate them into treated water and a dehydrated cake. When an amphoteric water-soluble polymer is used as the polymer flocculant of the present invention, it is preferable to use the inorganic flocculant in combination. Further, when the purpose is deodorization, dephosphorification, denitrification, etc., the pH of sludge is preferably less than 5.

The inorganic flocculant is not particularly limited, and examples thereof include a sulfate band, polyaluminum chloride, ferric chloride, ferrous sulfate, and polyferric sulfate.

The dehydrator is not particularly limited, and examples thereof include a screw press type dehydrator, a belt press type dehydrator, a filter press type dehydrator, a screw decanter, and a multiple disk.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. The methods for measuring various physical properties are as follows. The temperature condition for measuring various physical properties is 25 ° C. unless otherwise specified.

[Viscosity of 0.5% aqueous solution]
A sample (powder sample) in an amount of 0.50% by mass was added to 400 mL of pure water and sufficiently dissolved to prepare a sample solution. Using a B-type rotary viscometer, the viscosity of this sample solution at 25 ° C. and a rotor rotation speed of 12 rpm was measured.

[0.1% salt viscosity]
To a sodium chloride aqueous solution prepared by dissolving 5.84 g of sodium chloride in pure water to a total volume of 80.0 mL, add 20.0 mL of the sample solution after measuring the viscosity of the 0.5% aqueous solution to sufficiently dissolve the sample. A solution was prepared. The viscosity of this sample solution at 25 ° C. and a rotor rotation speed of 60 rpm was measured using a B-type rotary viscometer equipped with a BL adapter and a dedicated BL rotor.

[Volume specific density]
After the sample (powder sample) is poured into the container from the funnel set on the cylindrical container with a capacity of 25 cm ³ until it overflows, the heaped excess is removed cleanly, and the mass of the sample that fits perfectly in the cylindrical container. The bulk specific gravity was calculated from the ratio of the volume and the volume.

[Particle strength]
The sample (powder sample) was sieved with a stainless steel test sieve, and particles having a particle size of 1.0 to 1.7 mm were taken out. The particle strength of these particles was measured by the following method.

First, the first particle whose particle strength was to be measured was sandwiched between a laboratory table and a glass plate, and a load was applied from above the glass plate to compress the particles, and the load was gradually increased until the particles were destroyed. Then, the load at the moment when the particles were broken was measured with a hardness tester (trade name "TECLOCK Durometer GS-720G" manufactured by TECLOCK Co., Ltd.). Care was taken to keep the laboratory table and the glass plate as parallel as possible. In addition, a load was applied to the particles from directly above the particles via a glass plate with a needle of a hardness tester for measurement.

After measuring the load at the time of compression failure of the first particle, the same operation is repeated, the load at the time of compression failure of a total of 10 particles is measured, and the average value of the load is calculated as the particle strength (N). did.

[Flock diameter]
The size of the flocs (flock diameter) in the agglomerated sludge was visually measured.

[Gravity filterability]
Aggregated sludge was poured into a stainless steel test sieve having an inner diameter of 80 mm, a depth of 50 mm, and an opening of 250 μm or 180 μm at once, and gravity filtration was performed. At this time, set the funnel so that the filtrate enters the 200 mL graduated cylinder, measure the volume of the filtrate 5 seconds, 10 seconds, 20 seconds, and 30 seconds after the sludge is added, and perform gravity filtration. Gender was evaluated. Of these, the volume of the filtrate after 10 seconds was defined as the amount of liquid (mL) after 10 seconds.

[Appearance of filtrate]
The appearance of the filtrate after the evaluation of the gravity filterability was visually evaluated according to the following criteria.
⊚: No outflow of suspended component (SS) is observed in the filtrate.
〇: Almost no outflow of suspended component (SS) is observed in the filtrate.
Δ: A small amount of suspended component (SS) outflow is observed in the filtrate.
X: A large amount of suspended component (SS) flows out from the filtrate.

[Moisture content of dehydrated cake]
The sludge floc after gravity filtration remaining on the stainless steel test sieve after evaluating the gravity filterability was mechanically dehydrated according to the dehydration method and conditions described separately to obtain a dehydrated cake. The obtained dehydrated cake is taken out, weighed in an aluminum pan, dried in a hot air dryer at 105 ° C. for 16 hours, and then the mass after drying is measured. I asked for the rate.

[Removability of dehydrated cake from filter cloth]
When the dehydrated cake after the mechanical dehydration test was peeled off from the filter cloth, the state in which the dehydrated cake did not peel off cleanly from the filter cloth and remained on the filter cloth was visually evaluated according to the following criteria.
⊚: No residue of dehydrated cake is found on the filter cloth.
〇: Almost no dewatered cake remains on the filter cloth.
Δ: A small amount of dehydrated cake remains on the filter cloth.
X: A large amount of dehydrated cake remains on the filter cloth.

[Hand-squeezing evaluation of flock strength]
Take an appropriate amount of sludge floc after gravity filtration remaining on the stainless steel test sieve, squeeze the water contained in the sludge floc with one hand gradually and firmly in several steps, and squeeze SS and aggregates from between your fingers. The flock strength was evaluated according to the following criteria to see if it could be squeezed by hand without leaking.
⊚: No agglomerates leak between the fingers and can be squeezed tightly.
〇: Almost no agglomerates leak between the fingers and can be squeezed tightly.
Δ: A small amount of agglomerates leaks between the fingers, or
The dehydrated cake is a little sticky and difficult to squeeze hard.
×: A large amount of agglomerates leaks between the fingers, or
The dehydrated cake is so sticky that it cannot be squeezed tightly.

<Manufacturing example 1>
17.1 g of sorbitan sesquiolate having an HLB of 3.7 was weighed in a cylindrical separable flask having a capacity of 2 L, and 256.0 g of normal heptane was added and dissolved to prepare an oil phase. On the other hand, 463.8 g of a 79 mass% dimethylaminoethyl acrylate quaternary salt chloride aqueous solution and 67.2 g of a 50 mass% acrylamide aqueous solution were mixed in another beaker, and a 0.1 mass% aqueous solution of methylenebisacrylamide was used as a cross-linking agent. After adding 6 g, 0.8 g of isopropyl alcohol, 4.0 g of a 5 mass% aqueous solution of EDTA / disodium as a chelating agent, and 2.0 g of a 0.35 mass% aqueous solution of t-butyl hydroperoxide as an initiator, pure water. Was added, and the pH was adjusted to 4.0 with 98% sulfuric acid to prepare 682.6 g of an aqueous phase.

Next, the aqueous phase was added while stirring the oil phase in the separable flask, and the mixture was stirred at 10,000 rpm for 7 minutes at high speed with a homogenizer to prepare a water-in-oil emulsion having a median diameter of 1.5 μm. A separable cover equipped with a nitrogen gas blowing tube, a reflux condenser, and a thermometer was set in the flask, and degassing was started with nitrogen gas while stirring with a stirring blade. After sufficiently degassing, while supplying nitrogen gas, nitrogen gas containing 0.02 vol% of sulfur dioxide was further blown into the emulsion at a supply amount of 11.6 ml / min to initiate polymerization.

After reaching 50 ° C. and maintaining this temperature for 2 hours, the same initiator aqueous solution as the initial one was additionally added to increase the supply of nitrogen gas containing sulfur dioxide to 312.2 ml / min, and further at 50 ° C. 1 After holding for a time, the nitrogen gas and the nitrogen gas containing sulfur dioxide were stopped, and the polymerization was completed. Then, 4.0 g of a 1% by mass aqueous solution of sodium pyrosulfite and 9.7 g of a 50% by mass aqueous solution of malic acid were added and mixed to obtain a water-in-oil emulsion containing the desired water-soluble polymer. The composition ratio of the obtained water-in-oil emulsion was 45.4% by mass of solid content, 24.5% by mass of normal heptane, and 30.1% of water as a result of slight volatilization of normal heptane and water during polymerization. It was% by mass.

Next, a separable flask with a capacity of 300 mL equipped with a nitrogen gas inlet, a Dean Stark device with a reflux condenser on the top, a thermometer, and a vacuum gauge, a pressure control valve, and a vacuum pump on the reflux condenser. Into the flask, 100.0 g of a water-in-oil emulsion containing the water-soluble polymer obtained above and 25.4 g of normal heptane were charged so that the content of normal heptane was 1.1 times the mass of the solid content. Further, normal heptane was charged to the branch in the straight pipe portion under the reflux condenser, and nitrogen gas was flowed while stirring the inside of the flask with a stirring blade to replace the gas phase in the system with nitrogen.

After that, when the temperature of the oil bath began to rise to 130 ° C, the temperature of the water-in-oil emulsion also rose and reached the azeotropic boiling point at about 84 ° C, and azeotropic steam containing normal heptane and water began to appear. rice field. The azeotropic steam rises to the reflux condenser, condenses into a liquid, and falls into the straight pipe section. There, the water is phase-separated from normal heptane, and water collects in the lower phase of the straight pipe. On the other hand, since there is normal heptane in the upper phase of the straight pipe portion, the normal heptane overflowing from the straight pipe portion returns to the flask through the branch pipe. When the amount of water accumulated in the straight pipe portion increases in this way, the cock under the straight pipe portion is opened to drain the water, and this operation is repeated until the reflux dehydration step is completed. Then, after the dehydration rate reached 92%, the water-in-oil emulsion was cooled to 40 ° C. or lower to complete the reflux dehydration step.

As the reflux dehydration step progressed and the amount of water contained in the water-in-oil emulsion in the flask decreased, the boiling point increased and gradually approached the boiling point of normal heptane at 98 ° C.

Subsequently, after draining the residual liquid in the straight pipe portion of the Dean-Stark apparatus and the liquid receiving tank installed under it, the pressure is reduced to an absolute pressure of 13 kPa under stirring, and the oil bath is heated from room temperature to 90 ° C to reduce the pressure. It was dried. On the way, the temperature of the water-in-oil emulsion reached the boiling point at about 40 to 43 ° C., and steam containing normal heptane and the remaining water began to be emitted. The degree of vacuum was adjusted while observing the flow rate of the condensate, 90% or more of the total amount of the solvent was evaporated, and after confirming that the product temperature started to rise, finish drying was performed at an absolute pressure of 4 kPa for 30 minutes.

The cock under the straight pipe was always opened so that the condensate would not be collected in the straight pipe, and the condensate was collected in the liquid receiving tank under it. When the amount of condensate accumulated in the receiving tank increased, the cock under the straight pipe was closed, the vacuum in the receiving tank was returned with nitrogen, the condensate was discharged, and this operation was repeated until the drying process was completed. .. After 30 minutes, the drying step was completed, and the product temperature was cooled to 40 ° C. or lower to obtain a powdery water-soluble polymer. The powder sample at this stage has a solid content of 97.0% by mass and a bulk specific gravity of 0.40 g / cm ³ , and has extremely poor fluidity, and is a lightly agglomerated powder with powder characteristics that is difficult to handle. there were.

Furthermore, a stirring tank that combines a glass separable cover equipped with the same instrumentation as above and a stainless steel separable flask with a capacity of 300 mL is made of stainless steel so that the clearance between the bottom surface and the wall surface is about 1 mm. The anchor blades were set, 50 g of the powdery water-soluble polymer obtained above was charged, and the powder sample was heated by immersing it in an oil bath at 60 ° C. for 30 minutes with gentle stirring. Next, while stirring at a stirring speed of 200 rpm, 4 g of pure water as a binder was added with a syringe pump for about 4 minutes, and then the mixture was heated and stirred at an outside temperature of 60 ° C. for 30 minutes while being sealed and wet in a steamed state. Stirring granulation was performed.

Further, while stirring at 200 rpm, the pressure was reduced to an outside temperature of 60 ° C. and an absolute pressure of 7 kPa, and wet stirring granulation was continued for 30 minutes. Then, the temperature is raised to an outside temperature of 90 ° C., heat-dried under reduced pressure at an absolute pressure of 4 kPa for 1 hour, and then sieved with a stainless steel test sieve having a mesh size of 2.0 mm to remove coarse particles, and then granulated. It was designated as product 1. The coarse granules were crushed so as to pass through a sieve to obtain a granulated product 2. The granulated product 1 and the granulated product 2 were mixed to obtain a water-soluble polymer A1 having improved powder properties. The powder characteristics and physical properties of the obtained powder sample were evaluated and shown in Table 1.

<Manufacturing Examples 2 to 6>
The operation was the same as in Production Example 1 except that the composition of each monomer, the amount of the cross-linking agent added, the polymerization conditions such as the type and amount of the chain transfer agent added, and the granulation conditions were changed as shown in Table 1. As a result, water-soluble polymers A2 to A6 having improved powder properties were obtained. The powder characteristics and physical properties of the obtained powder sample were evaluated and shown in Table 1.

<Manufacturing example 7>
The composition of each monomer, the amount of cross-linking agent added, the polymerization conditions such as the type and amount of chain transfer agent added, and the granulation conditions were changed as shown in Table 1, and the initiator was changed to 2,2'-azobis ( Except for changing to 2.0 g of a 4% by mass aqueous solution of 2-methylpropionamidine) dihydrochloride, using only nitrogen gas instead of nitrogen gas containing sulfur dioxide, and changing the reaction temperature to 60 ° C. , The same procedure as in Production Example 1 was carried out to obtain a water-soluble polymer A7 having improved powder properties. The powder characteristics and physical properties of the obtained powder sample were evaluated and shown in Table 1.

<Manufacturing example 8>
727.0 g of a 79 mass% dimethylaminoethyl acrylate quaternary salt chloride aqueous solution and 131.7 g of a 40 mass% acrylamide aqueous solution were weighed in a stainless steel reaction vessel whose inner surface was coated with Teflon (registered trademark), and pure water was added. The total mass was 1100 g. After adjusting the pH of this solution to 4, the temperature of the solution was adjusted to 5 ° C. while blowing nitrogen gas into the solution for 60 minutes. Then, a polyfunctional acrylate-based cross-linking agent (manufactured by Toa Synthetic Co., Ltd .; trade name "Aronix M-306"), which is a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate, 2,2'-azobis (2-methylpropion). Amidin) dihydrochloride and sodium bisulfite are added by dissolving in a small amount of pure water or a solvent so that the total mass of each monomer pure content is 20 mass ppm, 300 mass ppm, and 30 mass ppm, respectively. did.

Next, this solution was irradiated with light from above the reaction vessel to carry out polymerization, and a water-containing gel-like water-soluble polymer was obtained. Four 10W blacklight fluorescent tubes are used for light irradiation, and after light irradiation for 30 minutes under the condition that ^{the irradiation intensity is 0.4mW / cm 2 with a UV illuminometer for 365nm, the light is switched to a 400W blacklight mercury lamp 60.} Light irradiation was continued for a minute. The obtained hydrogel was taken out from the reaction vessel, shredded with a chopper, dried with a hot air dryer at a temperature of 100 ° C. for 2.5 hours, and then pulverized to obtain a powdery water-soluble polymer B1. The powder characteristics and physical properties of the obtained powder sample were evaluated and shown in Table 1.

<Manufacturing example 9>
The powdery water-soluble polymer B2 was obtained in the same manner as in Production Example 8 except that the amount of sodium bisulfite added was changed as shown in Table 1 and the cross-linking agent was not added. rice field. The powder characteristics and physical properties of the obtained powder sample were evaluated and shown in Table 1.

<Manufacturing example 10>
Same as Production Example 8 except that no cross-linking agent and sodium bisulfite were added, and the amount of 2,2'-azobis (2-methylpropionamidine) dihydrochloride added was changed to 200 parts by mass ppm. To obtain a powdery water-soluble polymer B3. The powder characteristics and physical properties of the obtained powder sample were evaluated and shown in Table 1.

<Manufacturing example 11>
The composition of each monomer and the amount of sodium bisulfite added were changed as shown in Table 1, and 2,2'-azobis (2-methylpropion amidine) dihydrochloride without using a cross-linking agent. A powdery water-soluble polymer B4 was obtained in the same manner as in Production Example 8 except that the addition amount was changed to 1200 mass ppm. The powder characteristics and physical properties of the obtained powder sample were evaluated and shown in Table 1.

<Manufacturing example 12>
The composition of each monomer and the amount of sodium bisulfite added were changed as shown in Table 1, and 2,2'-azobis (2-methylpropion amidine) dihydrochloride without using a cross-linking agent. A powdery water-soluble polymer B5 was obtained in the same manner as in Production Example 8 except that the addition amount was changed to 1400 mass ppm. The powder characteristics and physical properties of the obtained powder sample were evaluated and shown in Table 1.

However, the abbreviations in Table 1 represent the following.
"Emulsion": Reverse-phase emulsion polymerization "Aqueous solution": Aqueous solution polymerization "DAC": Dimethylaminoethyl acrylate Methyl chloride quaternary salt "DAB": Dimethylaminoethyl acrylate benzyl chloride quaternary salt "DMC": Dimethylaminoethyl methacrylate methyl chloride Tertiary salt "AM": Acrylamide "AA": Acrylic acid "MBA": N, N'-methylenebisacrylamide "M-306": With pentaerythritol triacrylate
Mixture of pentaerythritol tetraacrylate
(Manufactured by Toagosei Co., Ltd .; product name "Aronix M-306")
"IPA": Isopropyl alcohol "NaH2PO2": Sodium hypophosphate "NaHSO3": Sodium bisulfite

<Production Examples 13 to 18, Comparative Production Example 1>
The powdery water-soluble polymers produced in Production Examples 1 to 3, 8 and 11 are mixed so as to be uniform in the mass ratio shown in Table 2 to obtain a powdery polymer flocculant. rice field.

<Examples 1 to 6, Comparative Examples 1 to 6>
A tabletop test of floc formation and dehydration treatment was conducted on sludge collected from a public sewage treatment plant. The properties of this sludge are pH = 5.2, TS = 38,200 mg / L, VTS / TS = 89.5% by mass, SS = 32,200 mg / L, VSS / SS = 91.3% by mass, Coarse suspended matter / SS = 46.6% by mass.

First, 200 mL of sludge was collected in a 300 mL beaker, and 0.2 mass of the polymer flocculant produced in Production Examples 13 to 18, Comparative Production Examples 1 and 1-3, Production Example 8 and Production Example 11 was added. % Aqueous solution was added with a syringe so that the polymer flocculant was added in the amount shown in Table 3 with respect to the sludge mass. The sludge was stirred with a spatula 150 times for 60 seconds to flock the sludge, and the flock diameter was visually measured. Next, the total amount of the aggregated sludge was poured into a stainless steel test sieve having an inner diameter of 80 mm, a depth of 50 mm, and an opening of 180 μm at once, and gravity filtration was performed. At this time, the funnel was set so that the filtrate would enter the 200 mL graduated cylinder, and the volume of the filtrate was measured every predetermined time to evaluate the gravity filterability. Moreover, the appearance of the filtrate was visually evaluated.

Next, the sludge floc after gravity filtration remaining on the stainless steel test sieve after evaluation of gravity filterability was placed on a filter cloth and squeezed with a mini belt press machine, and the dehydrated cake after squeezing was taken out and the dehydrated cake was taken out. The water content of the cake was measured. The results of these tests are shown in Table 3.

The conditions of the mini belt press machine are as follows. Number of squeezing roll stages = 3 stages, belt running speed = 0.5 m / min, surface pressure = 0.05 MPa, filter cloth type: Shikishima Campus T-1189L (sugi twill), filter cloth air permeability = 16 L / cm ² / min Is.

From Table 3, Examples 1 to 6 containing the water-soluble polymer (A) and the water-soluble polymer (B) in a specific mass ratio with respect to the sludge of the public sewage treatment plant are the water-soluble polymers (B). Although the amount of the polymer flocculant added was increased as compared with Comparative Examples 1 and 2 containing only), the amount of liquid after 10 seconds at the optimum amount of addition was significantly increased, and the gravity filterability was excellent. Further, in a wide range of addition amounts, the appearance of the filtrate was excellent, the water content of the dehydrated cake was as low as less than 71.0%, and the mechanical squeezing dehydration property was also excellent.

Further, in Examples 1 to 6, the optimum addition amount of the polymer flocculant tends to be reduced as compared with Comparative Examples 3 to 5 containing only the water-soluble polymer (A), and 10 seconds after the optimum addition amount. Since the amount of liquid and the water content of the dehydrated cake are also superior to those of Comparative Examples 3 to 5, the polymer flocculants of Examples 1 to 6 could be dehydrated with a small amount of addition and showed excellent dehydration performance. ..

<Manufacturing Examples 19 to 22>
The powdery water-soluble polymers produced in Production Examples 4 to 5 and Production Examples 9 to 10 were mixed so as to be uniform in the mass ratio shown in Table 4 to obtain a powdery polymer flocculant.

<Examples 7 to 10, Comparative Examples 7 to 9>
A tabletop test of floc formation and dehydration treatment was carried out on the wastewater treatment sludge of the pig farm collected from the purification treatment facility of urinary sewage of the pig farm. The properties of this sludge are pH = 5.8, TS = 38,000 mg / L, VTS / TS = 74.9% by mass, SS = 17,500 mg / L, VSS / SS = 88.0% by mass, The coarse suspended matter / SS = 6.63% by mass and the electric conductivity = 1,710 mS / m. Since this raw sludge is too viscous, the following evaluation was carried out using sludge obtained by adding the same volume of treated water to the collected raw sludge and diluting it twice.

First, 200 mL of sludge diluted in a 300 mL beaker was collected, and a 0.2% by mass aqueous solution of the polymer flocculant produced in Production Examples 19 to 22 and Production Examples 4, 5, and 9 was added to the high molecular weight coagulant. The molecular flocculants were added with a syringe so that the amount of the molecular flocculant was the amount shown in Table 5 with respect to the sludge mass. The sludge was stirred with a spatula for 60 seconds to flock the sludge, and the flock diameter was visually measured. Next, the total amount of the aggregated sludge was poured into a stainless steel test sieve having an inner diameter of 80 mm, a depth of 50 mm, and an opening of 180 μm at once, and gravity filtration was performed. At this time, the funnel was set so that the filtrate would enter the 200 mL graduated cylinder, and the volume of the filtrate was measured every predetermined time to evaluate the gravity filterability. Moreover, the appearance of the filtrate was visually evaluated.

Next, the sludge floc after gravity filtration remaining on the stainless steel test sieve after evaluation of gravity filterability was placed on a filter cloth and squeezed with a mini belt press machine, and the dehydrated cake after squeezing was taken out and the dehydrated cake was taken out. The releasability from the filter cloth was evaluated. The results of these tests are shown in Table 5.

The conditions of the mini belt press machine are as follows. Number of squeezing roll stages = 3 stages, belt running speed = 0.5 m / min, surface pressure = 0.05 MPa, filter cloth type: Polyester E-6080 manufactured by Nippon Filcon.

From Table 5, Examples 7 to 10 containing the water-soluble polymer (A) and the water-soluble polymer (B) in a specific mass ratio with respect to the wastewater-treated sludge of the pig farm are the water-soluble polymer (B). Although the amount of the polymer flocculant added was increased as compared with Comparative Example 7 containing only), the amount of liquid after 10 seconds at the optimum amount of addition was significantly increased, and the gravity filterability was excellent. In addition, the appearance of the filtrate and the peelability of the dehydrated cake from the filter cloth were also excellent.

Further, in Examples 7 to 10, the optimum addition amount of the polymer flocculant tends to be reduced as compared with Comparative Examples 8 to 9 containing only the water-soluble polymer (A), and 10 seconds after the optimum addition amount. Since the amount of the liquid, the appearance of the filtrate, and the releasability of the dehydrated cake from the filter cloth are excellent, the polymer flocculants of Examples 7 to 10 can be dehydrated with a small amount of addition and exhibit excellent dehydration performance. rice field.

<Manufacturing example 23>
The powdery water-soluble polymers produced in Production Example 7 and Production Example 11 were mixed so as to be uniform in the mass ratio shown in Table 6 to obtain a powdery polymer flocculant.

<Example 11, Comparative Examples 10 to 11>
A tabletop test of floc formation and dehydration treatment was carried out on the human waste treatment sludge collected from the human waste treatment facility. The properties of this sludge are pH = 6.7, TS = 18,200 mg / L, VTS / TS = 76.4% by mass, SS = 17,100 mg / L, VSS / SS = 77.8% by mass, Coarse suspended matter / SS = 0.59% by mass.

First, 200 mL of sludge was collected in a 300 mL beaker, and a 0.2% by mass aqueous solution of the polymer flocculant produced in Production Example 23, Production Example 7, and Production Example 11 was added to the sludge by the polymer flocculant with respect to the sludge mass. Each was added with a syringe so as to have the addition amount shown in Table 7. The sludge was stirred with a spatula 100 times for 30 seconds to flock the sludge, and the flock diameter was visually measured. Next, the total amount of the aggregated sludge was poured into a stainless steel test sieve having an inner diameter of 80 mm, a depth of 50 mm, and an opening of 250 μm at once, and gravity filtration was performed. At this time, the funnel was set so that the filtrate would enter the 200 mL graduated cylinder, and the volume of the filtrate was measured every predetermined time to evaluate the gravity filterability. Moreover, the appearance of the filtrate was visually evaluated.

Next, the sludge floc after gravity filtration remaining on the stainless steel test sieve after evaluation of gravity filterability was placed on a filter cloth and squeezed with a mini belt press machine, and the dehydrated cake after squeezing was taken out and the dehydrated cake was taken out. The water content of the cake was measured. The results of these tests are shown in Table 7.

The conditions of the mini belt press machine are as follows. Number of squeezing roll stages = 3 stages, belt running speed = 0.5 m / min, surface pressure = 0.05 MPa, filter cloth type: Shikishima Campus T-1189L (sugi twill), filter cloth air permeability = 16 L / cm ² / min Is.

From Table 7, Example 11 containing the water-soluble polymer (A) and the water-soluble polymer (B) in a specific mass ratio with respect to the sludge of the human waste treatment facility contains only the water-soluble polymer (B). Compared with Comparative Example 10, the amount of the polymer flocculant added was increased, but the amount of liquid after 10 seconds at the optimum amount of addition was significantly increased, and the gravity filterability was excellent. In addition, the appearance of the filtrate and the water content of the dehydrated cake were also excellent.

Further, in Example 11, as compared with Comparative Example 11 containing only the water-soluble polymer (A), the amount of the polymer flocculant added was wide, and the amount of the liquid after 10 seconds, the appearance of the filtrate, and the water content of the dehydrated cake were also improved. It was excellent and showed good dehydration performance. Regarding the water content of the dehydrated cake, the water content of Example 11 was improved by about 1% as compared with Comparative Examples 10 to 11, but this difference was significant. In addition to enabling stable treatment of the urine treatment facility, it can contribute to the reduction of electricity consumption and fuel consumption of the dehydrated cake drying and incinerator in the subsequent process.

<Manufacturing example 24>
The powdery water-soluble polymers produced in Production Example 6 and Production Example 12 were mixed so as to be uniform in the mass ratio shown in Table 8 to obtain a powdery polymer flocculant.

<Example 12, Comparative Examples 12 to 13>
A tabletop test of floc formation and dehydration treatment was carried out on the paper sludge collected from the paper mill. The properties of this sludge are pH = 6.6, TS = 41,200 mg / L, VTS / TS = 34.0% by mass, SS = 38,600 mg / L, VSS / SS = 33.9% by mass, The coarse suspended matter / SS = 3.63% by mass and the ash content = 66.1% by mass.

First, 200 mL of sludge was collected in a 300 mL beaker, and a 0.1% by mass aqueous solution of the first anionic polymer flocculant (manufactured by MT Aqua Polymer Co., Ltd .; trade name "Akovlock A-235H") was added thereto. The polymer flocculant was added with a syringe so as to be 10 mass ppm with respect to the sludge mass. The sludge was stirred with a spatula 50 times to flock the sludge.

Next, a 0.2% by mass aqueous solution of the polymer flocculant produced in Production Example 24, Production Example 6, and Production Example 12, which is the second cationic or amphoteric polymer flocculant, is subjected to sludge. Each was added with a syringe so that the amount added was as shown in Table 9 with respect to the mass. The sludge was mixed by transfer between beakers 10 times, and then stirred with a spatula 30 times to prepare the sludge flocs. The flock diameter at this time was visually measured. Then, the total amount of the aggregated sludge was poured into a stainless steel test sieve having an inner diameter of 80 mm, a depth of 50 mm, and an opening of 250 μm at once, and gravity filtration was performed. At this time, the funnel was set so that the filtrate would enter the 200 mL graduated cylinder, and the volume of the filtrate was measured every predetermined time to evaluate the gravity filterability. Moreover, the appearance of the filtrate was visually evaluated.

Next, take an appropriate amount of sludge flocs after gravity filtration remaining on the stainless steel test sieve after evaluating the gravity filterability, squeeze the water contained in the sludge flocs with one hand, and SS and aggregates from between the fingers. We evaluated the flock strength to see if it could be squeezed by hand without leaking. The results of these tests are shown in Table 9.

From Table 9, Example 12 containing the water-soluble polymer (A) and the water-soluble polymer (B) in a specific mass ratio with respect to the papermaking sludge is a comparative example containing only the water-soluble polymer (B). Although the amount of the polymer flocculant added was slightly increased as compared with No. 12, the amount of liquid after 10 seconds at the optimum amount of addition was significantly increased, and the gravity filterability was excellent. It was also excellent in the appearance of the filtrate and the evaluation of flock hand squeezing.

Further, in Example 12, compared with Comparative Example 13 containing only the water-soluble polymer (A), a wide range of addition amounts of the polymer flocculant was used to evaluate the amount of liquid after 10 seconds, the appearance of the filtrate, and the manual drawing of flocs. It was excellent and showed good dehydration performance.

Claims (11)

A water-soluble polymer (A) having a solution viscosity ratio of at least 900 or more and 10,000 or less represented by the following formula (1) and a water-soluble polymer (B) having a solution viscosity ratio of 100 or more and less than 900. ), And the content of the water-soluble polymer (A) is 5 to 90% by mass with respect to the total mass of the water-soluble polymer (A) and the water-soluble polymer (B). Cationic or amphoteric polymer flocculants.

However, the viscosity of the 0.5% aqueous solution is the viscosity (mPa · s) measured by using a B-type rotary viscometer at a rotor rotation speed of 12 rpm and 25 ° C. for a polymer aqueous solution having a concentration of 0.5% by mass. For the 0.1% salt viscosity, a 0.5% by mass concentration polymer aqueous solution was diluted to a 0.1% by mass concentration, and a 1N NaCl-dissolved polymer salt aqueous solution was used as a B-type rotary viscometer and a BL adapter. Is the viscosity (mPa · s) measured at a rotor rotation speed of 60 rpm and 25 ° C. The powdery polymer according to claim 1, wherein the water-soluble polymers (A) and (B) contain one or more cationic structural units having a structure represented by the following general formula (2). Coagulant.

However, R ¹ is a hydrogen atom or a methyl group, R ² and R ³ are independently alkyl groups or benzyl groups ^{having 1 to 3 carbon atoms, and R 4} is a hydrogen atom or an alkyl group or benzyl group having 1 to 3 carbon atoms. Yes, it may be of the same type or different types. X represents 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. The water-soluble polymers (A) and (B) contain at least one of a methyl quaternary salt of dimethylaminoethyl acrylate or a quaternary salt of benzyl chloride and a quaternary salt of methyl chloride of dimethylaminoethyl methacrylate. The powdery polymer flocculant according to claim 1 or 2, which is obtained by polymerizing a monomer mixture. The powdery polymer aggregation according to claim 3, wherein the water-soluble polymer (A) and / or (B) is obtained by further polymerizing a monomer mixture containing a nonionic monomer. Agent. The powdery polymer flocculant according to claim 4, wherein the nonionic monomer is acrylamide. The powdery state according to claim 4 or 5, wherein the water-soluble polymer (A) and / or (B) is obtained by further polymerizing a monomer mixture containing an anionic monomer. Polymer flocculant. The powdery polymer flocculant according to claim 6, wherein the anionic monomer is acrylic acid. The water-soluble polymers (A) and (B) are both ^{powders having a bulk specific gravity of 0.5 to 0.8 g / cm 3} , and at least one of the powders has a particle strength of 5 N or more. The powdery polymer flocculant according to any one of claims 1 to 7, which is a powder containing a granulated product which has been granulated in the above, and is a mixture of two or more kinds of the powder. A method for dehydrating sludge by adding at least one of the polymer flocculants according to any one of claims 1 to 8 to sludge to dehydrate the sludge. The 0.5% aqueous solution viscosity of the water-soluble polymer (A) is 1,000 to 15,000 mPa · s, and the 0.1% salt viscosity of the water-soluble polymer (A) is 1.1 to 3. It is 5 mPa · s, the 0.5% aqueous solution viscosity of the water-soluble polymer (B) is 500 to 3,500 mPa · s, and the 0.1% salt viscosity of the water-soluble polymer (B) is 1. The powdery polymer flocculant according to any one of claims 1 to 8, which is 8 to 7.0 mPa · s. The method for producing a powdery polymer flocculant according to any one of claims 1 to 8, wherein the powdery water-soluble polymer (A) is prepared by reverse phase emulsion polymerization and subjected to aqueous solution polymerization. A method for producing a powdery polymer flocculant by preparing the powdery water-soluble polymer (B) and mixing the two.