WO2020027312A1

WO2020027312A1 - Macromolecular coagulant and sludge dehydration method

Info

Publication number: WO2020027312A1
Application number: PCT/JP2019/030409
Authority: WO
Inventors: 伊藤　賢司; 剛鶴岡; 渡辺　浩史
Original assignee: Ｍｔアクアポリマー株式会社
Priority date: 2018-08-03
Filing date: 2019-08-02
Publication date: 2020-02-06
Also published as: JPWO2020027312A1; JP7362620B2

Abstract

The present invention addresses the problem of providing a high-performance macromolecular coagulant in powder form that shows outstanding dehydration performance on dehydration-resistant sludge, resolves transportation cost problems, and can be used in existing general-purpose equipment such as automatic powder melting devices and the like that have been in wide use. In particular, the present invention addresses the problem of providing an outstanding polymer coagulant that, in addition to exhibiting outstanding dehydration performance on dehydration-resistant sludge, can perform dehydration processing with only a small amount thereof. These problems can all be solved by a macromolecular coagulant in powder form that includes a water-soluble polymer (A) that shows specific solution properties and a water-soluble polymer (B) that shows solution properties different from those of the water-soluble polymer (A). That is, this macromolecular coagulant in powder form exhibits outstanding dehydration performance, resolves transportation cost problems, and can be used in existing general-purpose equipment such as automatic powder melting devices and the like that have been in wide use.

Description

Polymer flocculant and sludge dewatering method

The present invention relates to a polymer flocculant and a method for dewatering sludge. More specifically, the present invention provides a high-performance powdery polymer flocculant capable of effectively dewatering hardly dewaterable sludge and obtaining a dewatered cake having a low water content, and dewatering sludge using the same. About the method.

Polymer flocculants are used for flocculation, sedimentation and separation of suspended matter contained in domestic wastewater and industrial wastewater, as well as as a retention aid in the papermaking industry, as an admixture and mudifier in civil engineering and construction, etc. Used. The polymer flocculant has nonionic, anionic, cationic and amphoteric ionic properties, and which ionic agent to use depends on the properties of the water to be treated and the treatment method.

Among these, cationic polymer flocculants are used for flocculating and dewatering excess sludge after activated sludge treatment of industrial and domestic wastewater, or as a retention improver in the papermaking industry. There are many. For the sludge which is difficult to dewater in the former, a polymer having a branch or a crosslink is used. The amphoteric polymer flocculant is used to coarsely flocculate suspended particles charged and neutralized with a coagulant, and is used for sludge which is difficult to dewater and flocculate.

On the other hand, polymer coagulants conventionally have product forms such as powders and water-in-oil emulsions. Of these, water-in-oil emulsions have the advantage of being excellent in solubility and being able to dissolve uniformly in a short period of time, but on the other hand they are transported due to their higher production costs and lower active ingredient content of polymer flocculants than powders. There was a disadvantage that the cost was high.

Under these circumstances, recently, a cationic or amphoteric water-in-oil emulsion polymer having branching or cross-linking has been dried into a powdery product, and has demonstrated excellent dewatering performance even for hardly dewatered sludge, and has a low transport cost. A high-performance powdery polymer flocculant which can be used in existing equipment such as an automatic melting apparatus for general-purpose powders which has been widely used in the past has been developed.

For example, Patent Document 1 discloses that a water-soluble monomer mixture containing a cationic monomer and 5-2000 ppm of a crosslinking agent is subjected to reverse-phase polymerization in a non-aqueous liquid, and at least 90% by weight of a first monomer having a particle size of 10 μm or less. Method for producing spray-dried granules for producing a reverse-phase emulsion of the following polymer particles, and then spray-drying the reverse-phase emulsion to form spray-dried granules having a particle size of at least 90% by weight of 20 μm or more, and powder obtained. The use of the article as a polymeric flocculant is disclosed.

However, the spray-dried granules of the crosslinked polymer described in Patent Literature 1 have higher filtrate volume (filterability) at an optimal addition amount than the linear polymer and exhibit better performance, but have a higher polymer dose ( Addition amount). No measures are taken to reduce the amount added.

Patent Document 2 discloses a vinyl polymer-based crosslinkable water-soluble ionic polymer (A) having a charge inclusion ratio of 20% or more, corresponding to the mass% of 200 mesh-on particles in the sludge with respect to all suspended particles in the sludge. And a coagulant composition characterized by changing the blending ratio of a vinyl polymerizable linear water-soluble ionic polymer (B) having a charge inclusion ratio of 5% or more and less than 20%.

However, Patent Literature 2 shows that although using a different combination of the surface charges of polymer particles in a solution, excellent effects on dehydration and reduction of the amount of polymer added can be seen to some extent, but not sufficiently satisfactory. Did not. In particular, since the state of the surface charge varies depending on the kind and composition ratio of the cationic monomer used, the combination of the polymer properties is not always preferable, and it is insufficient to exhibit excellent dehydration performance for hardly dewatered sludge. Patent Document 2 describes only a water-in-oil emulsion and a dispersion in salt water as product forms, does not substantially cover powder products, and mentions the elimination of disadvantages in transportation costs. It has not been.

The present applicant has developed a sludge dehydrating agent comprising 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, even for hardly dewaterable sludge and hardly dewatering conditions, a larger amount of flocculated floc and a higher drainage amount can be obtained with a smaller amount of addition, and the obtained cake has a remarkably high water content. Lower, and good processing becomes possible. This sludge dewatering agent shows excellent dewatering performance. Also in this technique, there is no example of a powder product, and the powder product is not practically targeted, and there is room for study on the transportation cost.

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

The object of the present invention is to exhibit excellent dewatering performance even for hardly dewatered sludge, eliminate the disadvantages of transportation costs, and use it in existing facilities such as automatic melting equipment for general-purpose powders that have been widely used in the past. It is to provide a high-performance powdery polymer flocculant that can be used. In particular, it is an object of the present invention to provide an excellent polymer flocculant capable of performing a dehydration treatment with a small amount of addition in addition to exhibiting excellent dehydration performance for hardly dewatered sludge.

As a result of intensive studies, the present inventors have found that a powdery polymer agglomerate containing a water-soluble polymer (A) having specific solution properties and a water-soluble polymer (B) having different solution properties is provided. It has been found that the agent can solve all of the above problems. In other words, the powdery polymer flocculant of the present invention exhibits excellent dehydration performance, eliminates the disadvantages of transportation costs, and can be used in existing facilities such as a general-purpose automatic dissolution apparatus for general-purpose powder products that have been widely used. After confirming that it can be used, the present invention has been completed.

That is, the present invention
[1] At least a water-soluble polymer (A) having a solution viscosity ratio represented by the following formula (1) of at least 900 and less than 10,000, and a water-soluble polymer having a solution viscosity ratio of at least 100 and less than 900: (B), and the content of the water-soluble polymer (A) is 5 to 90% by mass based on the total mass of the water-soluble polymer (A) and the water-soluble polymer (B). Powdered cationic or amphoteric polymer flocculant.

However, the 0.5% aqueous solution viscosity is a viscosity (mPa · s) obtained by measuring a 0.5% by mass aqueous polymer solution using a B-type rotary viscometer at a rotor rotation speed of 12 rpm and 25 ° C. The 0.1% salt viscosity is obtained by diluting a 0.5% by mass aqueous polymer solution to 0.1% by mass and dissolving 1N NaCl in a polymer aqueous salt solution using a B-type rotary viscometer and a BL adapter. Is the viscosity (mPa · s) measured at 25 ° C. and a rotor rotation speed of 60 rpm.

[2] The powder according to [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). Polymer coagulant.

Provided that R ¹ is a hydrogen atom or a methyl group, R ² and R ³ are each independently an alkyl group or a benzyl group having 1 to 3 carbon atoms, and R ⁴ is a hydrogen atom, an alkyl group or a benzyl group having 1 to 3 carbon atoms. Yes, they may be the same or different. 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 methyl quaternary chloride or benzyl quaternary salt of dimethylaminoethyl acrylate and methyl quaternary chloride of dimethylaminoethyl methacrylate. The powdery polymer flocculant according to the above [1] or [2], which is obtained by polymerizing a monomer mixture containing a seed.

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

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

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

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

[8] Each of the water-soluble polymers (A) and (B) is a powder 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 5N or more. The powdery polymer according to any one of the above [1] to [7], which is a powder containing a granulated material that has been subjected to granulation so that two or more kinds of the powders are mixed. It is a flocculant.

[9] A sludge dewatering method in which at least one of the polymer coagulants according to any one of [1] to [8] is added to sludge and dewatered.

[10] A 0.5% aqueous solution viscosity of the water-soluble polymer (A) is 1,000 to 15,000 mPa · s, and a 0.1% salt viscosity of the water-soluble polymer (A) is 1.1. 0.5 to 3.5 mPa · s, the 0.5% aqueous 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 a 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. A method in which the powdery water-soluble polymer (B) is prepared by aqueous solution polymerization, and the both are mixed to produce a powdery polymer flocculant.

The polymer flocculant obtained in the present invention, in addition to exhibiting excellent dewatering performance even for hardly dewatered sludge, eliminates the disadvantage of transportation costs and has been widely used for conventional general-purpose powders. Existing equipment such as a melting device can also be used. In particular, it is possible to highly balance the conflicting performance of exhibiting excellent dewatering performance for hardly dewatered sludge and dewatering treatment with a small amount of addition. Such a high-performance powdery polymer flocculant can be provided.

Further, the polymer flocculant of the present invention is used as a flocculant / dewatering agent for domestic wastewater and industrial wastewater sludge, such as a papermaking drainage retention improver, a drainage improver, a formation formation aid, and a paper strength enhancer. It can be applied to a wide range of applications such as papermaking chemicals, coagulants for drilling and muddy water treatment, additives for increasing crude oil, organic coagulants, thickeners, dispersants, scale inhibitors, antistatic agents, and fiber treatment agents. It is possible.

Hereinafter, the present invention will be described in detail.
In this specification, acrylate and / or methacrylate are represented as (meth) acrylate, acrylamide and / or methacrylamide are represented as (meth) acrylamide, and acrylic acid and / or methacrylic acid are represented as (meth) acrylic acid. And an acid and a salt thereof are referred to as an acid (salt).

The polymer flocculant of the present invention exhibits excellent dehydration performance for hardly dewatered sludge and, in order to realize excellent performance for dehydration treatment with a small amount of addition, a water-soluble agent showing specific solution physical properties. It contains a polymer (A) and a water-soluble polymer (B) exhibiting different solution physical properties.

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).

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

溶液 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 coagulation will not occur unless the added amount is increased from several times to several tens times as compared with a normal linear type polymer flocculant, so that it is economical. Is not realistic from a simple point of view. On the other hand, when the solution viscosity ratio is less than 900, the degree of cross-linking is too low, so that excellent dewatering performance for hardly dewatered sludge cannot be exhibited. The solution viscosity ratio of the water-soluble polymer (A) is preferably from 950 to 5,000, and most preferably from 1,000 to 3,500.

０．５ The 0.5% aqueous solution viscosity of the water-soluble polymer (A) of the present invention is preferably 1,000 to 15,000 mPa · s. If the 0.5% aqueous solution viscosity exceeds 15,000 mPa · s, the degree of crosslinking is too high, and if the addition amount is not increased from several times to several tens of times compared with a normal linear type polymer flocculant, aggregation occurs. May not be realistic from an economic point of view. On the other hand, when the 0.5% aqueous solution viscosity is less than 1,000 mPa · s, the degree of crosslinking is too low or the molecular weight is too low, so that it may not be possible to exhibit excellent dewatering performance for hardly dewatered sludge. The viscosity of the 0.5% aqueous solution of the water-soluble polymer (A) is more preferably from 1,500 to 10,000 mPa · s, and most preferably from 2,000 to 6,000 mPa · s.

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

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

溶液 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 dehydration performance on hardly dewatered sludge and has a small addition. It is not possible to highly balance the conflicting performance of being able to perform dehydration treatment in a large amount. On the other hand, when the solution viscosity ratio is less than 100, the molecular weight and the ionicity are too low, and sufficient performance as a polymer flocculant cannot be realized. The solution viscosity ratio of the water-soluble polymer (B) is preferably from 150 to 850, particularly preferably from 200 to 800.

０．５ The 0.5% aqueous solution viscosity of the water-soluble polymer (B) of the present invention is preferably from 500 to 3,500 mPa · s. If the 0.5% aqueous solution viscosity 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 hardly dewatered sludge. There is a case where it is not possible to highly balance the conflicting performance of performing the dehydration treatment with a small amount of addition. On the other hand, when the 0.5% aqueous solution viscosity is less than 500 mPa · s, the molecular weight and ionicity are too low, and sufficient performance as a polymer flocculant may not be realized. The 0.5% aqueous solution viscosity of the water-soluble polymer (B) is more preferably from 700 to 3,000 mPa · s, most preferably from 900 to 2,500 mPa · s.

水溶 The water-soluble polymer (B) of the present invention preferably has a 0.1% salt viscosity of 1.8 to 7.0 mPa · s. When 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), excellent dewatering for hardly dewatered sludge is achieved. In some cases, it may not be possible to achieve a high degree of balance between contradictory performances of demonstrating performance and performing 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 are too low, and sufficient performance as a polymer flocculant may not be realized. The 0.1% salt viscosity of the water-soluble polymer (B) is more preferably from 2.0 to 5.6 mPa · s, most preferably from 2.2 to 3.9 mPa · s.

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

では In the present invention, the content of the water-soluble polymer (A) is 5 to 90% by mass based on the total mass of the water-soluble polymer (A) and the water-soluble polymer (B). When the content of the water-soluble polymer (A) is more than 90% by mass, the performance of the water-soluble polymer (A) is too strong, and if the added amount is not increased, the water-soluble polymer (A) does not aggregate, which is not preferable from an economic viewpoint. When 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, so that it is impossible to exhibit excellent dehydration performance for hardly dewatered sludge. The content of the water-soluble polymer (A) is preferably from 10 to 80% by mass, particularly preferably from 10 to 70% by mass.

では In the present invention, the content of the water-soluble polymer (B) is 10 to 95% by mass based on the total mass of the water-soluble polymer (A) and the water-soluble polymer (B). When the content of the water-soluble polymer (B) exceeds 95% by mass, the performance of the water-soluble polymer (B) is too strong, so that it is impossible to exhibit excellent dehydration performance for hardly dewatered 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 added amount is increased. The content of the water-soluble polymer (B) is preferably from 20 to 90% by mass, particularly preferably from 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. it can. The monomer mixture may contain, in addition to the cationic monomer, another monomer copolymerizable with the cationic monomer, if necessary. Further, the water-soluble polymers (A) and (B) preferably include one or more cationic constitutional units having a structure represented by the following general formula (2).

The cationic monomer that can be used in the present invention may be any monomer having a radical polymerizable double bond and a cationic group capable of undergoing radical polymerization, and may be any of the compounds represented by the following general formula (3). Other examples include diallyldialkylammonium halides such as diallyldimethylammonium chloride. Among these cationic monomers, the radical polymerization reactivity is excellent, it is easy to increase the molecular weight required as a polymer flocculant, and the resulting polymer has excellent performance as a polymer flocculant, A compound represented by the following general formula (3) is preferred.

Wherein R ¹ is a hydrogen atom or a methyl group, R ² and R ³ are each independently an alkyl group or a benzyl group having 1 to 3 carbon atoms, and R ⁴ is a hydrogen atom, an alkyl group or a benzyl group having 1 to 3 carbon atoms. Yes, they may be the same or different. 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 ions.

Specific examples of the cationic monomer represented by the general formula (3) include dialkyl such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, and dimethylamino-2-hydroxypropyl (meth) acrylate. Examples include quaternary salts such as aminoalkyl (meth) acrylate hydrochlorides and sulfates, halogenated alkyl adducts such as methyl chloride, benzyl halide adducts such as benzyl chloride, and dialkyl sulfate adducts such as dimethyl sulfate. Is done. Also, hydrochlorides and sulfates of dialkylaminoalkyl (meth) acrylamides such as dimethylaminopropyl (meth) acrylamide, alkyl halides such as methyl chloride, benzyl halides such as benzyl chloride, and sulfuric acids such as dimethyl sulfate A quaternary salt such as a dialkyl adduct is also exemplified.

Among these preferred cationic monomers, a quaternary salt which is a methyl chloride adduct of dimethylaminoethyl acrylate and a methyl chloride adduct of dimethylaminoethyl methacrylate which are particularly easy to increase the molecular weight required for a polymer flocculant Are most preferred. In addition, a quaternary salt which is a benzyl chloride adduct of dimethylaminoethyl acrylate is preferred for treating sludge having a high salt concentration (high electric conductivity) discharged from livestock such as a pig farm. These cationic monomers may be used alone or in combination of two or more.

において In the present invention, any monomer that can be copolymerized with the cationic monomer can be used without any particular limitation. Among these, nonionic monomers and anionic monomers are exemplified below.

Examples of the nonionic monomer include (meth) acrylamide-based compounds, and (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and hydroxyethyl (meth) acrylate. Examples thereof include alkyl acrylate, styrene, acrylonitrile, and vinyl acetate. Among these nonionic monomers, (meth) acrylamide is preferable because it is easy to increase the molecular weight required as a polymer flocculant and has excellent performance as a polymer flocculant. Acrylamide, which has particularly excellent performance as a molecular coagulant, is most preferred. 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-acrylamido-2-methylpropanesulfonic acid, maleic acid and the like, and salts thereof. Among these anionic monomers, (meth) acrylic acid and salts thereof are preferable because they can be easily made into a high molecular weight as a polymer flocculant and have excellent performance as a polymer flocculant. 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.

配合 There is no particular limitation on the mixing ratio (molar ratio) of each monomer in the monomer mixture. 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 from 3 to 98 mol%, particularly preferably from 5 to 95 mol%.

The crosslinkable monomer is used for the purpose of introducing a branch or a crosslinked structure into the polymer chain. As the crosslinkable monomer, methylene bisacrylamide or di (meth) acrylate represented by the following formula (4) is preferable. In the latter, di (meth) acrylate to which polyethylene glycol and / or polypropylene glycol having high water solubility is added is preferable. preferable. Among these, methylene bisacrylamide having a small molecular weight, being water-soluble, and having high reactivity is particularly preferable.

Here, R ⁵ and R ⁶ are each 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 preferred amount of the crosslinkable monomer varies depending on the type, molecular weight and reactivity of the crosslinkable monomer used, but is generally preferably from 1 to 1,000 ppm based on the total mass of all monomer mixtures. , More preferably 1 to 500 ppm, most preferably 1 to 200 ppm. If it is added in excess of 1,000 ppm, the degree of crosslinking is too high and the coagulation performance as a polymer coagulant 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 solution polymerization, reverse phase suspension, and the like. Polymerization, reversed-phase emulsion polymerization and the like are exemplified. Among these, the water-soluble polymer (A) is easy to adjust the primary particle diameter (median diameter) of the water-soluble polymer to 10 μm or less and to adjust the solution viscosity ratio to 900 or more and 10,000 or less. The application of reverse emulsion polymerization is preferred. On the other hand, for the water-soluble polymer (B), it is preferable to apply aqueous solution polymerization, which can easily adjust the solution viscosity ratio to 100 or more and less than 900, and is advantageous in terms of production cost in industrial production.

In the present invention, when producing a powdery polymer coagulant, 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. ) Is prepared, and the two are mixed to produce a powdery polymer flocculant.

(1) Application Example of Reverse Emulsion Polymerization When applying reverse emulsion polymerization, a hydrocarbon which is substantially immiscible with water is generally used in the continuous phase. In the polymer flocculant of the present invention, it is necessary to dry the continuous phase hydrocarbon for powderization after emulsion polymerization, reflux dehydration if necessary. Therefore, hydrocarbons having a very high boiling point are not preferred, and those having a boiling point at normal pressure in the range of 65 to 130 ° C. are preferred. Specifically, normal heptane is preferred.

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

Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene alkyl ether, polyoxyethylene alkylene alkyl ether, sorbitan monooleate, sorbitan sesquiolate, and sorbitan monolau. Rate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbite tetraoleate, polyethylene glycol monooleate, polyethylene glycol dioleate, oleic acid diethanolamide, lauric acid monoethanolamide, monostearic acid mono Nonionic surfactants such as ethanolamide can be mentioned.
The effective addition amount of these surfactants is preferably from 0.25 to 15% by mass, more preferably from 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 monomers used, the initiator, and the physical properties of the polymer. The polymerization temperature is from 0 to 100 ° C, preferably from 10 to 80 ° C. The monomer concentration is preferably from 20 to 50% by mass, more preferably from 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 paramenthane 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 known compounds such as redox initiators comprising a combination of an oxidizing agent such as hydrogen peroxide or persulfate and a reducing agent such as sodium sulfite or ferrous sulfate. Is mentioned. These polymerization initiators may be used alone or in combination of two or more.

公知 A known chain transfer agent can be used as a method for adjusting the molecular weight. Known chain transfer agents include thiol compounds such as mercaptoethanol and mercaptopropionic acid, reducing inorganic salts such as sodium sulfite, sodium bisulfite and sodium hypophosphite, alcohols such as ethanol and isopropyl alcohol, and methallyl. (Meth) allyl compounds such as sodium sulfonate.

他 In addition, additives such as a stabilizer, a pH adjuster, and an antioxidant may be added as long as the effects of the present invention are not impaired.

When the water-soluble polymer (A) is obtained by reversed-phase emulsion polymerization among the polymer flocculants of the present invention, 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. Preferably, the thickness is 0.5 to 5 μm, more preferably 0.7 to 3 μm. When the median diameter exceeds 10 μm, the coagulation performance of the polymer coagulant is significantly reduced. Even if the median diameter is smaller than 0.3 μm, the performance of the polymer flocculant is not improved, and the treatment of increasing the amount of the emulsifier or applying higher shear with an emulsifier is not preferred. After adding the aqueous phase of the aqueous solution of the monomer mixture to the oil phase obtained by dissolving the surfactant in the hydrocarbon so that the median diameter of the primary particles of the water-soluble polymer falls within the above range, the emulsion is emulsified using an emulsifier. It is preferable to keep it.

前 Before drying the water-soluble polymer of the water-in-oil emulsion obtained by the reverse-phase emulsion polymerization, it is preferable to remove water in the emulsion by reflux dehydration so that the emulsion is not destroyed. When drying without reflux dehydration or with insufficient water removal, the drying of the hydrocarbon proceeds before the water, depending on the boiling point of the hydrocarbon, and the water-containing polymer particles fuse together to form a huge It becomes a hydrogel deposit. In that case, it is difficult to sufficiently dry the remaining water, or the water-containing polymer solidifies in a glass state while adhering to the walls and bottoms of the stirring tank or the dryer, so that it is difficult to take out and powder it.

粉末 After the reflux dehydration, the remaining water and hydrocarbons are dried from the slurry in which the water-soluble polymer is dispersed, whereby a powdery water-soluble polymer can be suitably obtained.

Alternatively, as an alternative, the water-soluble polymer of the water-in-oil emulsion obtained by reverse phase emulsion polymerization, without reflux dehydration, or after removing some water by reflux dehydration, spray-drying It can be powdered. However, as described in the background art, because of the characteristics of the spray dryer, it is necessary to dry in a small amount in a short time, so it is necessary to dry at a very high temperature, and a high molecular weight water-soluble polymer causes thermal deterioration. In some cases, the viscosity of the solution is easily affected, the quality varies, or the target solution viscosity ratio cannot be adjusted. In that case, it is necessary to reduce the drying temperature and further dry the resin little by little to suppress thermal deterioration.

When the polymer flocculant of the present invention is obtained by reverse-phase emulsion polymerization, after obtaining a powdery water-soluble polymer by the above operation, further after wet stirring granulation, drying, sieving, crushing and the like as necessary It is preferable to adjust the powder characteristics so as to be easily used as a polymer flocculant. As an example of the powder characteristics, coarse particles having a particle size exceeding 1.7 mm and fine particles having a particle size of less than 180 μm are each preferably 10% by mass or less, and more preferably 5% by mass or less. A large amount of coarse particles is not preferred because the dissolution rate of the polymer coagulant powder in water is reduced. On the other hand, if the amount of the fine powder is too large, it is unpreferable because the working environment of a person handling the polymer flocculant is deteriorated because the fine powder is formed. Further, 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. The bulk specific gravity is preferably from 0.5 to 0.8 g / cm ³ , and more preferably from 0.6 to 0.7 g / cm ³ .

Furthermore, when a powdery water-soluble polymer is granulated, the particle strength of the granulated product is preferably from 5 to 50N, more preferably from 10 to 40N, and most preferably from 15 to 30N. When the particle strength is less than 5N and is insufficient, a part of the granulated particles may be disintegrated and returned to the fine powder during transportation or use of the granulated product. On the other hand, if the particle strength exceeds 50 N, the quality of the polymer flocculant is excessive and the cost is increased, which is not preferable.

(2) Application Example of Aqueous Solution Polymerization In the case of applying aqueous solution polymerization, a method of polymerizing 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 to 5.

ラジカル The radical polymerization initiator used in the polymerization reaction is not particularly limited. In the case of aqueous polymerization, persulfates such as potassium persulfate and ammonium persulfate, organic peroxides such as t-butyl hydroperoxide, azo compounds such as azobisisobutyronitrile, redox initiators and photopolymerization An initiator or the like can be appropriately used.

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

The polymerization initiation temperature is usually preferably from 0 to 35 ° C. The polymerization time is usually preferably 0.1 to 3 hours. Further, the polymerization reaction is preferably performed in an inert atmosphere in the absence of oxygen. These polymerization conditions are known. After the completion of the polymerization reaction, post-treatments such as heat treatment, drying, and pulverization are performed as necessary. Known methods can be applied to these post-treatments.

光 Among the aqueous solution polymerizations, light irradiation polymerization is particularly preferred because the physical properties and quality of the resulting water-soluble polymer are small, stable production is possible, and physical properties are 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 an aqueous solution of the monomer mixture with light in the presence of a photopolymerization initiator and a chain transfer agent. Is exemplified.

光 The photopolymerization initiator used for the photoirradiation polymerization is not particularly limited. Preferred examples of the photopolymerization initiator include an acetophenone-based photopolymerization initiator and an azo-based initiator. Among them, the solubility of the monomer mixture in the aqueous solution is high, and the high molecular weight required as a polymer flocculant is required. A water-soluble azo-based initiator is particularly preferred because it is easy.

具体 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.

添加 The addition amount of the photopolymerization initiator is not particularly limited. What is necessary is just to adjust suitably according to the kind of photoinitiator, the molecular weight of a water-soluble polymer, the monomer composition, and the content of a residual monomer. In the case of a water-soluble azo-based initiator, it is usually preferably 100 to 3,000 ppm by mass based on the total mass of each monomer in the monomer mixture.

The chain transfer agent used in the photoirradiation polymerization is added mainly for the purpose of adjusting the molecular weight of the water-soluble polymer and suppressing the generation of insolubles, but the type thereof is not particularly limited. Examples of the chain transfer agent that can be used in the aqueous solution polymerization include sodium bisulfite, sodium sulfite, sodium hypophosphite, mercaptoethanol, and isopropanol. Among these, sodium bisulfite is preferred because the solubility of the monomer mixture in the aqueous solution is high, the effect is high even with a small amount of addition, and the molecular weight of the water-soluble polymer can be easily adjusted.

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

添加 The amount of the chain transfer agent is not particularly limited. What is necessary is just to adjust suitably according to the kind of chain transfer agent, the molecular weight of a water-soluble polymer, a monomer composition, the addition amount of a crosslinking monomer, and the insoluble amount. In the case of sodium bisulfite, usually, it is preferably 1 to 100 ppm by mass based on the total mass of each monomer in the monomer mixture.

The light irradiation conditions such as light wavelength, irradiation intensity, irradiation time and the like used in the light irradiation polymerization are not particularly limited. What is necessary is just to adjust suitably according to the kind and addition amount of the photoinitiator used, and the physical property and performance of a water-soluble polymer. When the water-soluble azo initiator is used as the photopolymerization initiator, light having a wavelength of about 365 nm is preferable, and the irradiation intensity is preferably from 0.1 to 1.0 mW / cm ² measured by a 365-nm UV illuminometer. The irradiation time is usually preferably 0.1 to 3 hours.

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

When the water-soluble polymer (B) is obtained by aqueous polymerization among the polymer flocculants of the present invention, the weight-average molecular weight of the water-soluble polymer is preferably 1,000,000 to 20,000,000. When the weight average molecular weight is less than 1,000,000, the ability to form sludge floc as a polymer flocculant is insufficient, and the floc diameter may not be sufficiently large. Further, when the weight average molecular weight exceeds 20,000,000, the crosslinking reaction may proceed too much, in which case the insoluble amount insoluble in water increases, and the amount of the active ingredient effectively acting as a polymer flocculant is reduced. Not only does it decrease, but it can also cause troubles that block the pump at the site that sends the solution in which the polymer flocculant is dissolved in water.

Sludge Dewatering Method In the sludge dewatering method of the present invention in which at least one polymer flocculant is added and dewatered, 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 human waste and its wastewater generated in livestock related industries such as pig farms Various types of sludge, such as sludge generated in the treatment, pulp or sludge generated in the paper industry, are to be treated. There is no limitation on the type of sludge, and primary sludge, surplus sludge, mixed sludge thereof, concentrated sludge, digested sludge treated with anaerobic microorganisms, and the like are all treated.

汚 The method for dewatering sludge of the present invention is characterized in that at least one of the polymer flocculants of the present invention is added to the above-mentioned various sludges for dewatering.

具体 Specific examples of the dehydration method include the following methods. That is, an inorganic coagulant is added to the sludge as needed, and the pH is preferably adjusted to 4 to 7. Thereafter, the polymer flocculant of the present invention is added to this sludge, and the suspension in sludge and the polymer flocculant are allowed to act by stirring and / or mixing by a known method to form sludge floc. The formed sludge floc is separated into treated water and a dewatered cake by mechanically dewatering by a known means. 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. When the purpose is deodorization, dephosphorization, denitrification, or the like, the pH of the sludge is preferably adjusted to less than 5.

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

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

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

[0.5% aqueous solution viscosity]
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 make the total volume 80.0 mL, add 20.0 mL of the sample solution after measuring the 0.5% aqueous solution viscosity, and sufficiently dissolve the sample. A solution was prepared. Using a B-type rotary viscometer equipped with a BL adapter and a dedicated BL rotor, the viscosity of this sample solution at 25 ° C. and a rotor rotation speed of 60 rpm was measured.

(Bulk specific gravity)
After pouring the sample (powder sample) into the container from the funnel set on the cylindrical container having a capacity of 25 cm ³ until the sample overflows, the excess piled up is removed neatly, and the mass of the sample exactly fit in the cylindrical container. The bulk specific gravity was determined 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 for measuring the particle strength was sandwiched between an experimental bench 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 broken. Then, the load at the moment when the particles were broken was measured with a hardness meter (trade name “Teklock durometer GS-720G” manufactured by Teclock Ltd.). Care was taken to keep the laboratory bench and the glass plate as parallel as possible. In addition, the measurement was performed by applying a load to the particles from directly above the particles via a glass plate with a needle of a hardness meter.

After measuring the load at the time of compressive fracture of the first particle, the same operation was repeated, the load at the time of compressive fracture of a total of 10 particles was measured, and the average value of the loads was determined to obtain the particle strength (N). did.

(Flock diameter)
The size (floc diameter) of flocs in the flocculated sludge was measured visually.

(Gravity filterability)
Agglomerated 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 a stretch, and gravity filtration was performed. At this time, the funnel is set so that the filtrate enters the 200 mL measuring cylinder, and the volume of the filtrate after 5 seconds, 10 seconds, 20 seconds, and 30 seconds has elapsed after sludge is introduced, and gravity filtration is performed. The sex was evaluated. Of these, the volume of the filtrate after the lapse of 10 seconds was defined as the liquid volume (mL) after 10 seconds.

[Appearance of filtrate]
The appearance of the filtrate after the evaluation of the gravity filterability was visually evaluated based on the following criteria.
A: No outflow of the suspension component (SS) was observed in the filtrate.
〇: Almost no outflow of the suspension component (SS) was observed in the filtrate.
Δ: A small amount of suspension component (SS) was found in the filtrate.
×: A large amount of suspension component (SS) was found in the filtrate.

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

[Removability of dewatered 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 remained on the filter cloth without being peeled cleanly from the filter cloth was visually evaluated according to the following criteria.
A: No residue of the dehydrated cake is observed on the filter cloth.
〇: Little residue of dehydrated cake is found on the filter cloth.
Δ: Some amount of dehydrated cake remains on the filter cloth.
×: A large amount of dehydrated cake remains on the filter cloth.

[Hand drawing evaluation of flock strength]
Take an appropriate amount of the sludge floc after gravity filtration left on the stainless steel test sieve, squeeze the water contained in the sludge floc slowly and firmly in several steps with one hand, and squeeze SS or aggregates between fingers. The flock strength of whether or not hand-drawing was possible without leakage was evaluated according to the following criteria.
：: Aggregates do not leak at all from between the fingers and can be firmly squeezed.
〇: Aggregates hardly leak from between fingers, and can be squeezed firmly.
Δ: Aggregate slightly leaks from between fingers, or
The dehydrated cake is slightly sticky and difficult to squeeze hard.
×: a large amount of aggregate leaks from between fingers, or
The dehydrated cake is quite sticky and cannot be squeezed firmly.

<Production Example 1>
17.1 g of sorbitan sesquiolate having an HLB of 3.7 was weighed into 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, in another beaker, 463.8 g of a 79% by mass aqueous solution of dimethylaminoethyl acrylate methyl chloride quaternary salt and 67.2 g of a 50% by mass aqueous solution of acrylamide were mixed, and a 0.1% by mass aqueous solution of methylenebisacrylamide as a crosslinking agent was mixed. 6 g, 0.8 g of isopropyl alcohol, 4.0 g of a 5% by weight aqueous solution of a chelating agent EDTA disodium, and 2.0 g of a 0.35% by weight aqueous solution of t-butyl hydroperoxide as an initiator were added to 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 to the separable flask while stirring the oil phase, and the mixture was stirred at 10,000 rpm for 7 minutes 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 on the flask, and degassing was started with nitrogen gas while stirring with a stirring blade. After sufficient degassing, while feeding nitrogen gas, nitrogen gas containing 0.02 vol% of sulfur dioxide was further blown into the emulsion at a supply rate of 11.6 ml / min to start polymerization.

After reaching 50 ° C. and maintaining this temperature for 2 hours, the same initiator aqueous solution as in the initial stage was additionally added, and the supply amount of nitrogen gas containing sulfur dioxide was increased to 312.2 ml / min. After holding for a time, the nitrogen gas and the nitrogen gas containing sulfur dioxide were stopped to terminate the polymerization. Thereafter, 4.0 g of a 1% by weight aqueous solution of sodium pyrosulfite and 9.7 g of a 50% by weight aqueous solution of malic acid were added and mixed to obtain a water-in-oil emulsion containing the desired water-soluble polymer. The component ratio of the obtained water-in-oil emulsion was such that normal heptane and water volatilized slightly during polymerization, so that the solid content was 45.4% by mass, normal heptane was 24.5% by mass, and water was 30.1% by mass. % By mass.

Subsequently, a 300-mL separable flask equipped with a nitrogen gas inlet, a Dean-Stark apparatus equipped with a reflux condenser at the top, a thermometer, and a vacuum gauge, a pressure regulating valve, and a vacuum pump above the reflux condenser. Was charged with 100.0 g of a water-in-oil emulsion containing the water-soluble polymer obtained above and 25.4 g of normal heptane so that the content of normal heptane was 1.1 times the mass of the solid content, Further, normal heptane was charged into the straight pipe portion below the reflux condenser to the point of the branch, and a nitrogen gas was flown while the inside of the flask was stirred with a stirring blade to replace the gas phase in the system with nitrogen.

Then, when the temperature of the oil bath started to rise to 130 ° C., the temperature of the water-in-oil emulsion also rose to reach an azeotropic point at about 84 ° C., and an azeotropic vapor containing normal heptane and water began to be emitted. Was. The azeotropic vapor rises to the reflux condenser, condenses and becomes a liquid, and falls into a straight pipe portion. There, water separates from normal heptane, and water accumulates in the lower phase of the straight pipe. On the other hand, since normal heptane is present in the upper phase of the straight pipe, normal heptane overflowing from the straight pipe and overflowing returns to the flask through the branch pipe. When the amount of water accumulated in the straight pipe section increases, the cock below the straight pipe section is opened to remove 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, and the reflux dehydration step was completed.

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

Subsequently, after draining the residual liquid in the straight pipe part of the Dean-Stark apparatus and the liquid receiving tank installed thereunder, the pressure was reduced to 13 kPa absolute under stirring, and the temperature of the oil bath was raised from room temperature to 90 ° C. to reduce the pressure. Drying was performed. 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, and 90% or more of the total amount of the solvent was evaporated. After confirming that the product temperature started to rise, finish drying was performed at 4 kPa absolute pressure for 30 minutes.

The cock below the straight pipe was always opened so that the condensed liquid did not pool in the straight pipe, and the condensate was stored in the liquid receiving tank below. When the amount of condensed liquid accumulated in the receiving tank increased, the cock under the straight pipe part was closed, the vacuum of the receiving tank was returned with nitrogen, and the condensed liquid was discharged. 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, a bulk specific gravity of 0.40 g / cm ³ , a powder having extremely poor fluidity, a lightly agglomerated powder having a powder property and being difficult to handle. there were.

Further, in a stirring tank combining a glass separable cover equipped with the same instrumentation as described above and a stainless steel separable flask having a capacity of 300 mL, a stainless steel separable tank was used so that the clearance between the bottom surface and the wall surface was about 1 mm. 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 a 60 ° C. oil bath for 30 minutes while stirring slowly. Next, 4 g of pure water as a binder was added by a syringe pump in about 4 minutes while increasing the stirring speed to 200 rpm and stirring, and the mixture was heated and stirred at an external temperature of 60 ° C. for 30 minutes while being sealed, and wet-steamed. Agitation granulation was performed.

Further, while stirring at 200 rpm, the pressure was reduced to an external temperature of 60 ° C. and an absolute pressure of 7 kPa, and the wet stirring granulation was continued for 30 minutes. Thereafter, the temperature was raised to an external temperature of 90 ° C., dried by heating under reduced pressure at an absolute pressure of 4 kPa for 1 hour, and then sieved with a stainless steel test sieve having an aperture of 2.0 mm to remove coarse particles and granulate what passed through. The product 1 was obtained. The coarse particles were crushed so as to pass through a sieve to obtain granulated product 2. The granulated product 1 and the granulated product 2 were mixed to obtain a water-soluble polymer A1 having improved powder characteristics. In addition, the powder properties and physical properties of the obtained powder samples were evaluated, and the results are shown in Table 1.

<Production Examples 2 to 6>
The same operation as in Production Example 1 was performed except that the polymerization conditions such as the composition of each monomer, the amount of the crosslinking agent added, the type and amount of the chain transfer agent, and the granulation conditions were changed as shown in Table 1. Thus, water-soluble polymers A2 to A6 having improved powder properties were obtained. In addition, the powder properties and physical properties of the obtained powder samples were evaluated, and the results are shown in Table 1.

<Production Example 7>
The polymerization conditions such as the composition of each monomer, the addition amount of the crosslinking agent, the type and amount of the chain transfer agent, and the granulation conditions were changed as shown in Table 1, and the initiator was 2,2'-azobis ( Except that 2.0 g of a 4% by weight aqueous solution of 2-methylpropionamidine) dihydrochloride was used, only nitrogen gas was used instead of nitrogen gas containing sulfur dioxide, and the reaction temperature was changed to 60 ° C. In the same manner as in Production Example 1, a water-soluble polymer A7 having improved powder properties was obtained. In addition, the powder properties and physical properties of the obtained powder samples were evaluated, and the results are shown in Table 1.

<Production Example 8>
In a stainless steel reaction vessel having an inner surface coated with Teflon (registered trademark), 727.0 g of a 79% by mass aqueous solution of dimethylaminoethyl acrylate methyl chloride quaternary salt and 131.7 g of a 40% by mass aqueous solution of acrylamide were weighed, and pure water was added. The total mass was 1100 g. After adjusting the solution to pH = 4, the temperature of the solution was adjusted to 5 ° C. while blowing nitrogen gas into the solution for 60 minutes. Thereafter, a polyfunctional acrylate-based cross-linking agent (manufactured by Toagosei Co., Ltd .; trade name “Aronix M-306”), which is a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate, 2,2′-azobis (2-methylpropion) Amidine) dihydrochloride and sodium bisulfite are dissolved in a small amount of pure water or a solvent so as to be 20 mass ppm, 300 mass ppm, and 30 mass ppm, respectively, with respect to the total mass of each monomer pure, and added. did.

Next, the solution was irradiated with light from above the reaction vessel to carry out polymerization to obtain a water-soluble gel-like water-soluble polymer. Four 10 W black light fluorescent tubes were used for the light irradiation, and after irradiating the light with a UV illuminometer for 365 nm at a irradiation intensity of 0.4 mW / cm ² for 30 minutes, the light was switched to a 400 W black light mercury lamp for 60 minutes. Light irradiation was continued for minutes. The obtained hydrogel was taken out of the reaction vessel, cut into pieces with a chopper, dried with a hot air drier at a temperature of 100 ° C. for 2.5 hours, and pulverized to obtain a powdery water-soluble polymer B1. In addition, the powder properties and physical properties of the obtained powder samples were evaluated, and the results are shown in Table 1.

<Production Example 9>
A 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 no crosslinking agent was added. Was. In addition, the powder properties and physical properties of the obtained powder samples were evaluated, and the results are shown in Table 1.

<Production Example 10>
Same as Production Example 8 except that the crosslinking agent and sodium bisulfite were not added, and that the addition amount of 2,2′-azobis (2-methylpropionamidine) dihydrochloride was changed to 200 mass ppm. To obtain a powdery water-soluble polymer B3. In addition, the powder properties and physical properties of the obtained powder samples were evaluated, and the results are shown in Table 1.

<Production Example 11>
The composition of each monomer and the amount of sodium bisulfite added were changed as shown in Table 1, and the use of 2,2′-azobis (2-methylpropionamidine) dihydrochloride was carried out without using a crosslinking 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. In addition, the powder properties and physical properties of the obtained powder samples were evaluated, and the results are shown in Table 1.

<Production Example 12>
The composition of each monomer and the amount of sodium bisulfite added were changed as shown in Table 1, and the use of 2,2′-azobis (2-methylpropionamidine) dihydrochloride was carried out without using a crosslinking 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. In addition, the powder properties and physical properties of the obtained powder samples were evaluated, and the results are 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 Quaternary salt “AM”: acrylamide “AA”: acrylic acid “MBA”: N, N′-methylenebisacrylamide “M-306”: mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (manufactured by Toagosei Co., Ltd .; Product name "Aronix M-306")
"IPA": isopropyl alcohol "NaH2PO2": sodium hypophosphite "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 were uniformly mixed at the mass ratio shown in Table 2 to obtain a powdery polymer flocculant. Was.

<Examples 1 to 6, Comparative Examples 1 to 6>
Table tests of floc formation and dewatering were conducted on sludge collected from public sewage treatment plants. The properties of this sludge were as follows: 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, Crude suspension / 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 Example 1, Production Examples 1 to 3, Production Examples 8, and 11 was added thereto. % Aqueous solution was added with a syringe so that the amount of the polymer flocculant became the amount shown in Table 3 with respect to the sludge mass. This sludge was stirred 150 times in a spatula for 60 seconds to flocculate the sludge, and the floc diameter was visually measured. Next, the entire 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 a stretch, and gravity filtration was performed. At this time, the funnel was set so that the filtrate could enter the 200 mL measuring cylinder, and the volume of the filtrate was measured every elapse of a predetermined time to evaluate the gravity filterability. Further, the appearance of the filtrate was visually evaluated.

Next, the sludge floc after gravity filtration remaining on the stainless steel test sieve after the gravity filterability was evaluated was placed on a filter cloth and squeezed with a mini belt press, and the dehydrated cake after the completion of the compression was taken out. Was measured for water content. Table 3 shows the test results.

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

Table 3 shows that Examples 1 to 6 containing the water-soluble polymer (A) and the water-soluble polymer (B) at a specific mass ratio with respect to the sludge of the public sewage treatment plant show that the water-soluble polymer (B) ), The amount of the polymer flocculant added was increased, but the amount of liquid after 10 seconds at the optimum amount was significantly increased, and the gravity filtration property was excellent. In addition, over a wide range of addition, the appearance of the filtrate was excellent, the water content of the dehydrated cake was low at less than 71.0%, and the mechanical press dewatering property was also excellent.

Further, in Examples 1 to 6, the optimum amount of the polymer coagulant tended to be reduced as compared with Comparative Examples 3 to 5 containing only the water-soluble polymer (A). Since the liquid volume and the water content of the dewatered cake were also superior to Comparative Examples 3 to 5, the polymer flocculants of Examples 1 to 6 could be subjected to dehydration treatment with a small amount of addition and exhibited excellent dehydration performance. .

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

<Examples 7 to 10, Comparative Examples 7 to 9>
Table tests of floc formation and dehydration treatment were performed on wastewater treatment sludge from swine farms collected from the purification facility of urine wastewater from swine farms. The properties of this sludge were as follows: 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, Crude suspended matter / SS = 6.63 mass%, and electric conductivity = 1,710 mS / m. Since the raw sludge was too viscous, the following evaluation was performed using sludge diluted twice by adding the same volume of treated water to the collected raw sludge.

First, 200 mL of the diluted sludge was collected in a 300 mL beaker, and a 0.2% by mass aqueous solution of the polymer flocculant produced in Production Examples 19 to 22, Production Examples 4, 5, and 9 was added thereto. The molecular coagulant was added with a syringe so that the amount of addition was as shown in Table 5 with respect to the sludge mass. The sludge was stirred with a spatula for 60 seconds to flocculate the sludge, and the floc diameter was visually measured. Next, the entire 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 a stretch, and gravity filtration was performed. At this time, the funnel was set so that the filtrate could enter the 200 mL measuring cylinder, and the volume of the filtrate was measured every elapse of a predetermined time to evaluate the gravity filterability. Further, the appearance of the filtrate was visually evaluated.

Next, the sludge floc after gravity filtration remaining on the stainless steel test sieve after the gravity filterability was evaluated was placed on a filter cloth and squeezed with a mini belt press, and the dehydrated cake after the completion of the compression was taken out. The peelability from the filter cloth was evaluated. Table 5 shows the test results.

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

From Table 5, it is found that Examples 7 to 10 containing the water-soluble polymer (A) and the water-soluble polymer (B) at a specific mass ratio with respect to the wastewater treatment sludge of the pig farm are the water-soluble polymers (B). ), The amount of the polymer coagulant added was increased, but the amount of liquid after 10 seconds at the optimum amount was significantly increased, and excellent in gravity filterability. Further, the appearance of the filtrate and the releasability of the dewatered cake from the filter cloth were excellent.

Further, in Examples 7 to 10, the optimum amount of the polymer flocculant tended to be reduced as compared with Comparative Examples 8 to 9, which contained only the water-soluble polymer (A). The polymer coagulants of Examples 7 to 10 can be subjected to dehydration treatment with a small amount of addition, and exhibit excellent dehydration performance, because they are excellent in the liquid amount, the appearance of the filtrate, and the removability of the dewatered cake from the filter cloth. Was.

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

<Example 11, Comparative Examples 10 to 11>
Table tests of floc formation and dehydration treatment were performed on human waste treated sludge collected from a human waste treatment facility. The properties of this sludge were 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, Crude suspension / 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 Examples 23, 7, and 11 was added thereto. In addition, each was added with a syringe so that the addition amounts shown in Table 7 were obtained. The sludge was stirred 100 times for 30 seconds with a spatula to flocculate the sludge, and the floc diameter was visually measured. Next, the whole 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 a stretch, and gravity filtered. At this time, the funnel was set so that the filtrate could enter the 200 mL measuring cylinder, and the volume of the filtrate was measured every elapse of a predetermined time to evaluate the gravity filterability. Further, the appearance of the filtrate was visually evaluated.

Next, the sludge floc after gravity filtration remaining on the stainless steel test sieve after the gravity filterability was evaluated was placed on a filter cloth and squeezed with a mini belt press, and the dehydrated cake after the completion of the compression was taken out. Was measured for water content. Table 7 shows the test results.

From Table 7, Example 11 including the water-soluble polymer (A) and the water-soluble polymer (B) at a specific mass ratio with respect to the sludge of the night soil treatment facility includes only the water-soluble polymer (B). Although the amount of the polymer flocculant added was larger than that of Comparative Example 10 which was not used, the liquid amount after 10 seconds at the optimum amount was significantly increased, and the gravity filtration property was excellent. In addition, the appearance of the filtrate and the water content of the dehydrated cake were excellent.

Further, in Example 11, compared with Comparative Example 11 containing only the water-soluble polymer (A), the amount of the liquid after 10 seconds, the appearance of the filtrate, and the water content of the dehydrated cake with a wide addition amount of the polymer flocculant were also observed. Excellent, showing good dehydration performance. The moisture content of the dehydrated cake in Example 11 was improved by about 1% as compared with Comparative Examples 10 to 11, but the difference was significant. In addition to enabling stable processing of the night soil treatment facility, it can contribute to drying of the dewatered cake in the subsequent process and reduction of power consumption and fuel consumption of the incinerator.

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

<Example 12, Comparative Examples 12 and 13>
Table tests of floc formation and dehydration treatment were performed on papermaking sludge collected from a paper mill. The properties of this sludge were as follows: 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, Crude suspension / SS = 3.63% by mass, 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 “Acofloc 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. This sludge was stirred with a spatula 50 times to flocculate the sludge.

Next, a 0.2% by mass aqueous solution of the polymer flocculant prepared in Production Examples 24 and 6 and 12, which is the second cationic or amphoteric polymer flocculant, was mixed with sludge. Each was added with a syringe so that the addition amount was as shown in Table 9 with respect to the mass. After mixing the sludge by transferring it between beakers 10 times, the mixture was further stirred with a spatula 30 times and adjusted to granulate the sludge floc. The floc diameter at this time was measured visually. Thereafter, the whole 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 a stretch, and gravity filtered. At this time, the funnel was set so that the filtrate could enter the 200 mL measuring cylinder, and the volume of the filtrate was measured every elapse of a predetermined time to evaluate the gravity filterability. Further, the appearance of the filtrate was visually evaluated.

Then, take an appropriate amount of the sludge floc after gravity filtration remaining on the stainless steel test sieve after evaluating the gravity filterability, squeeze the water contained in the sludge floc with one hand, and SS or aggregates between the fingers. The flock strength was evaluated as to whether the hand could be squeezed without leakage. Table 9 shows the test results.

From Table 9, Example 12 including the water-soluble polymer (A) and the water-soluble polymer (B) at a specific mass ratio with respect to the papermaking sludge is a comparative example including only the water-soluble polymer (B). Although the addition amount of the polymer flocculant was slightly increased as compared with 12, the liquid amount after 10 seconds at the optimum addition amount was significantly increased, and the gravity filtration property was excellent. In addition, the appearance of the filtrate and the evaluation of the hand-drawing of the floc were excellent.

Further, in Example 12, even compared with Comparative Example 13 containing only the water-soluble polymer (A), the amount of the liquid after 10 seconds, the appearance of the filtrate, and the evaluation of the hand-drawing of floc with a wide addition amount of the polymer flocculant were compared. Excellent, showing good dehydration performance.

Claims

At least a water-soluble polymer (A) having a solution viscosity ratio represented by the following formula (1) of 900 or more and 10,000 or less, and a water-soluble polymer (B) having a solution viscosity ratio of 100 or more and less than 900 Wherein the content of the water-soluble polymer (A) is 5 to 90% by mass based on the total mass of the water-soluble polymer (A) and the water-soluble polymer (B). A cationic or amphoteric polymer flocculant;

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

Provided that R 1 is a hydrogen atom or a methyl group, R 2 and R 3 are each independently an alkyl group or a benzyl group having 1 to 3 carbon atoms, and R 4 is a hydrogen atom, an alkyl group or a benzyl group having 1 to 3 carbon atoms. Yes, they may be the same or different. 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 quaternary methyl chloride salt or a quaternary benzyl chloride salt of dimethylaminoethyl acrylate and a quaternary methyl chloride salt 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 product 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.
7. The powdery polymer flocculant according to claim 6, wherein the anionic monomer is acrylic acid.
Each of the water-soluble polymers (A) and (B) is a powder 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 5N or more. The powdery polymer flocculant according to any one of claims 1 to 7, wherein the powder comprises a granulated material, and is a mixture of two or more kinds of the powders.
方法 A method for dewatering sludge, wherein at least one of the polymer coagulants according to any one of claims 1 to 8 is added to sludge and dewatered.
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. 5 mPa · s, 0.5% aqueous viscosity of the water-soluble polymer (B) is 500 to 3,500 mPa · s, and 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 has a viscosity of 8 to 7.0 mPa · s.
The method for producing a powdery polymer coagulant according to any one of claims 1 to 8, wherein the powdery water-soluble polymer (A) is prepared by reverse-phase emulsion polymerization, and the aqueous polymer is prepared by aqueous solution polymerization. A method for preparing a powdery water-soluble polymer (B) and mixing the two to produce a powdery polymer flocculant.