JP3315194B2 - Sludge dewatering agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a tertiary amino group or a tertiary amino group.
The present invention relates to a sludge dewatering agent having a graded ammonium carbonate base.

[0002]

2. Description of the Related Art Sludge dewatering agents have been widely used as sewage sludge, industrial wastewater sludge coagulants and dehydration aids because they exhibit excellent coagulation performance and dehydration performance in small amounts and can be incinerated. Conventionally, a water-soluble vinyl polymer having a quaternary ammonium group or an ammonium group neutralized with a mineral acid or the like has been used as a sludge dewatering agent. For example, Japanese Patent Publication No. 2-52040, Japanese Patent Publication No. 63-51141, Japanese Patent Publication No. 63-48863, Japanese Patent Publication No. 58-15491, and Japanese Patent Application Laid-Open No. 57-133670 disclose alkyl halides such as methyl chloride and ethyl chloride. And dimethyl sulfate, diethyl sulfate and the like, and JP-A-57-51899 discloses a polymer quaternized with benzyl chloride.
In addition, Japanese Patent Publication No. 2-52040, Japanese Patent Publication No. 58-15491
JP-A-58-49410, JP-A-58-4700
No. 5, JP-A-57-133670, and the like, mention is made of a polymer formed by using a mineral acid such as hydrochloric acid, sulfuric acid, phosphoric acid or the like, or a salt formed using acetic acid.
Is disclosed. In addition, in recent years, sludge that is hard to coagulate and hardly dehydrate has increased due to the sophistication of wastewater treatment, etc., and a coagulant with excellent dewatering properties that can cope with this, or stable sludge fluctuation due to simplified operation and maintenance. For example, JP-A-1-189400 discloses a sludge which acts as a tertiary amino group-containing polymer by adding a basic substance to a cationic polymer having a tertiary amino group formed therein. Dehydrating agents have been reported.

[0003]

However, a water-soluble vinyl polymer having a quaternary ammonium group or an ammonium group neutralized with a mineral acid or the like has an insufficient effect on sludge that is difficult to coagulate and hardly dehydrate. When a basic substance is added to a cationic polymer in which a tertiary amino group is formed, the effect of the tertiary amino group-containing polymer is not always exhibited, and the neutralization by the basic substance is completely performed. For this reason, the form is limited to a dilute solution of 0.2 to weight%, and there is a problem in practical use in terms of transportation, handling, and the like.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to develop a sludge dewatering agent which is excellent in sludge dewatering and can be used in any form such as powder, aqueous solution and emulsion. Along with establishing a method of synthesizing an acrylic polymer having a tertiary amino group, which has been considered difficult,
The problem can be solved by using the acrylic polymer as a sludge dewatering agent, and furthermore, by combining a water-soluble vinyl polymer containing the acrylic polymer as an essential component with a general-purpose coagulant, it is possible to overcome the disadvantages of the conventional general-purpose coagulant. Found and arrived at the present invention. That is, the present invention exhibits stable cohesion and good dewatering against sludge with a small amount of additives, reduction 6 (wherein, R1 is a hydrogen atom or a methyl group, R2, R3 is an alkyl group of C ₁ -C ₄ , N is 2-4
Represents an integer. And / or a structural unit represented by the formula
(Wherein R1 is a hydrogen atom or a methyl group, R2 and R3 are C
An alkyl group of ₁ to ₄ and n represents an integer of 2 to 4. The present invention provides a sludge dehydrating agent containing a water-soluble vinyl polymer having an intrinsic viscosity [η] of 1 dl / g or more, containing 10 mol% or more of a structural unit represented by formula (1).

[0005]

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[0006]

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The chemical formula 6 used in the present invention (wherein R ₁ , R
₂ , R ₃ and n are the same as described above) and / or
Wherein R ₁ , R ₂ , R ₃ and n are the same as defined above, wherein R ₁ is a hydrogen atom or a methyl group, and R 2 and R 3 are C ₁ -C ₄ alkyl groups. , N is 2
Shows an integer of ~ 4. Examples of the acrylic monomer represented by) include N, N-dimethylaminopropyl (meth) acrylamide, N, N-diethylaminopropyl (meth) acrylamide, and N, N-dimethylaminobutyl (meth).
Acrylamide, N, N-diethylaminobutyl (meth) acrylamide, N, N-methylethylaminopropyl (meth) acrylamide and the like are exemplified.

The acrylic monomer represented by the formula (8) (wherein R ₁ , R ₂ , R ₃ and n are the same as above) is represented by the formula (9)
R1 is a hydrogen atom or a methyl group, R2, R3 is C ₁ -C ₄
And n represents an integer of 2 to 4. ) Is converted to an acrylic monomer having a tertiary ammonium carbonate. The reaction is carried out by reacting the aqueous solution of acrylic monomer with carbon dioxide at normal pressure or under pressure, preferably under pressure.

[0009]

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[0010]

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The resulting acryl monomer containing tertiary ammonium carbonate can be easily polymerized by known radical polymerization recipes alone or with another copolymerizable vinyl monomer. _{1, R 2, R 3,} n
Is the same as described above) to produce a water-soluble polymer containing a structural unit represented by the following formula:

Other copolymerizable vinyl monomers include quaternary salts and neutralized salts of acrylic monomers, (meth) acrylamide, N-isopropylacrylamide, N-
Examples thereof include methylacrylamide, dimethylamino (meth) acrylamide, various (meth) acrylates, (meth) acrylic acid, and acrylonitrile. The polymer represented by the formula (7) (wherein R ₁ , R ₂ , R ₃ and n are the same as above) is heated or / and decarboxylated under reduced pressure to obtain a _third polymer.
By converting to a primary amino group,
₁ , R ₂ , R ₃ , and n are the same as those described above).

The above-mentioned chemical formula 6 contained in the polymer (wherein R
₁ , R ₂ , R ₃ , and n are the same as those described above, or
_{If the} structural unit represented by ( ₁ , R ₂ , R ₃ , and n is the same as described above) is less than 5 mol%, it is difficult to exhibit excellent aggregation performance. In order to achieve this, the content is preferably 10 mol% or more. If the intrinsic viscosity [η] of the polymer is less than 1, sufficient cohesion performance cannot be obtained, so that at least the intrinsic viscosity [η] is preferably 1 or more. The compound of the formula (6) (wherein R
_{1, R 2, R 3,} n is in the same) and / or of 7 _{(wherein, R 1, R 2, R} 3, n contains 5 mol% or more of structural units represented by the same) and the When a water-soluble vinyl polymer having an intrinsic viscosity [η] of 1 or more is used as a sludge dewatering agent as a dewatering aid for sludge, a vinyl polymer having a strong cation formed by a quaternary salt type or a mineral acid as a counter ion is obtained. In contrast, the flocculation and dewatering performance drops sharply before and after the optimum amount of addition to sludge, but shows a high dehydration rate and stable performance over a wide range of addition amount. Compared with the vinyl polymer used as the counter ion, it has characteristics that are not heretofore such as that the cake has good removability from the filter cloth. Incidentally, Chemical Formula 7
(Wherein R ₁ , R ₂ , R ₃ , and n are the same as those described above). Under actual conditions of use, most of the structural units are decarboxylated and converted to 6 (where R ₁ , R ₂ , R ₃ , and n are the same as those described above).

Further, according to the present invention, the above-mentioned chemical formula 6 and / or chemical formula 7
A water-soluble vinyl monomer having a structural unit represented by the following as an essential component can be used in combination with a general-purpose coagulant. Examples of general-purpose coagulants that can be used include the following: wherein R ₄ and R ₅ are hydrogen or methyl groups, p is a natural number, and q is 0.
Or it shows a natural number. ) Are preferred.

[0015]

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The polymer represented by Chemical Formula 10 can be synthesized by copolymerization of a quaternary salt of N, N-dimethylamino (meth) acrylate methyl chloride and a (meth) acrylamide derivative, and the composition ratio is arbitrary. The addition ratio of the general-purpose flocculant represented by Chemical Formula 10 to the vinyl polymer containing the structural unit represented by Chemical Formula 6 and / or Chemical Formula 7 as an essential component is not particularly limited; In consideration of the above, usually, a sufficient effect can be obtained by adding 5% by weight or more of the vinyl polymer having the structural units of Chemical Formulas 6 and 7 as an essential component to the general-purpose flocculant represented by Chemical Formula 10. Can be As a method of adding the present dehydrating agent to sludge, a general-purpose coagulant is added to sludge after mixing in an arbitrary amount, or a general-purpose coagulant is added to sludge immediately after being added to sludge, or the present dehydration improver Is added to the sludge, and then a general-purpose coagulant is added to the sludge.

[0017]

The present invention will be specifically described below with reference to examples. Production Example 1 (Synthesis of carbonate monomer) Glass 1 equipped with a thermometer, a pressure gauge and a carbon dioxide gas inlet tube
In an L autoclave, N, N-dimethylaminopropylacrylamide (hereinafter abbreviated as DMAPAA) 28
1.2 g, pure water 240.8 g, and p-methoxyphenol 0.7 g as a polymerization inhibitor were added, and carbon dioxide gas was supplied at 0 ° C. under a light-shielding and stirring at a pressure of ² kg / cm ² . 24
After reacting for 60 hours, the DMAPAA carbonate 60% by weight aqueous solution 56
3 g were obtained. Weight change before and after the reaction (522.7g →
563.0 g) and the pH change of the reaction solution, pH 13 to p
From H8, it is determined that DMAPAA carbonate was produced. Production Example 2 Benzyldimethylketal 0.03% by weight and EDTA-2Na were added to 60 g of a DMAPAA carbonate 60% by weight aqueous solution.
The mixture to which 0.01% by weight was added was put into a 500 ml three-neck separable flask equipped with a temperature sensor, a gas inlet pipe and a gas exhaust pipe, and polymerized with a low-pressure mercury lamp having a strength of 1 w / m2 from the bottom of the flask under a carbon dioxide gas flow. Irradiation was performed until the temperature reached a peak. Then, the mixture was irradiated with a high-pressure mercury lamp of 50 w / m 2 intensity for 3 minutes to carry out polymerization to obtain a DMAPAA carbonate polymer. When the intrinsic viscosity of the obtained polymer was measured at 25 ° C. with a 1N aqueous solution of NaCl, [η] = 3.7 (dl /
g).

Production Example 3 The polymer obtained in Production Example 2 was decarboxylated at 40 ° C. to obtain a DMAPAA polymer having a tertiary amino group. When the intrinsic viscosity of the obtained polymer was measured at 25 ° C. with a 1N aqueous solution of NaCl, [η] = 3.6 (dl / g).
Met. Production Example 4 The same treatment as in Production Example 2 was carried out except that benzyldimethylketal was changed to 0.10% by weight and EDTA-2Na to 0.03% by weight. By performing carbonation, a DMAPAA polymer was obtained.
The intrinsic viscosity of the obtained polymer measured at 25 ° C. with a 1N aqueous solution of NaCl was [η] = 1.2 (dl / g). Production Example 5 N, N- was added to 11 g of a 60% by weight aqueous solution of DMAPAA carbonate.
Dimethylaminoethyl methacrylate methyl chloride quaternary ammonium salt (hereinafter abbreviated as DM-C) 36.8 g of 80% by weight aqueous solution, 12.2 g of pure water (DMAPAA carbonate: DM-C = 2: 8) The molar ratio) was polymerized in the same manner as in Production Example 2, and then decarboxylation was carried out in the same manner as in Production Example 3 to obtain a DMAPAA / DM-C copolymer polymer. When DM-C in the obtained polymer was analyzed by a quaternary ammonium salt measuring method, the quaternary ammonium value was 84%.
Was calculated to be about 2: 8. The intrinsic viscosity of the present polymer in a 1N aqueous solution of NaCl at 25 ° C. is [η].
= 4.5 (dl / g). Production Example 6 Aqueous 50% by weight acrylamide solution (hereinafter abbreviated as AAm) in 41.2 g of a 60% by weight aqueous solution of DMAPAA carbonate.
18.8 g (DMAPAA carbonate: AAm = 1: 1 molar ratio) was polymerized in the same manner as in Preparation Example 2, and then decarboxylation was performed in the same manner as in Preparation Example 3 to obtain a DMAPAA / AAm copolymer polymer. As a result of analyzing the polymer by colloid titration, the degree of cationization was 69%, and DMAPAA:
The molar ratio of AAm was about 1: 1. 25 of this polymer
The intrinsic viscosity of a 1N aqueous solution of NaCl at ℃ is [η] = 6.
7 (dl / g). Production Example 7 26 g of the 60% by weight aqueous solution of the DMAPAA polymer obtained in Production Example 3 and 14.2 g of a 50% by weight aqueous solution of an acrylamide polymer of [η] = 9.7 (dl / g) were stirred and blended. (DMAPAA polymer: AAm polymer =
Production Example 8 60 g of a 60% by weight aqueous solution of N, N-dimethylaminopropyl (meth) acrylamide carbonate (hereinafter abbreviated as DMAPMA carbonate) was polymerized in the same manner as in Production Example 2, and then polymerized. The same treatment as in Production Example 3 was performed to obtain a DMAPMA polymer.
The intrinsic viscosity of the obtained polymer measured at 25 ° C. with a 1N aqueous solution of NaCl was [η] = 3.4 (dl / g). Production Example 9 A 60 wt% aqueous solution of N, N-dimethylaminoethylacrylamide carbonate (hereinafter abbreviated as DMAEAA carbonate) (60 g) was polymerized in the same manner as in Production Example 2, and then treated in the same manner as in Production Example 3, to give a DMAEAA polymer. I got The intrinsic viscosity of the obtained polymer measured at 25 ° C. with a 1N aqueous solution of NaCl was [η] = 3.5 (dl / g).

Comparative Production Example 1 60 g of a 60% by weight aqueous solution of DMAPAA was placed in a 500 ml three-neck separable flask equipped with a temperature sensor, a gas inlet tube and a gas exhaust tube, and a low pressure of 1 w / m 2 from the bottom of the flask under carbon dioxide gas flow. Irradiation was performed with a mercury lamp. Then, the mixture was irradiated with a high-pressure mercury lamp having a strength of 50 w / m 2 for 3 minutes to carry out polymerization, and the content was a syrup having fluidity.
The intrinsic viscosity of the obtained polymer was measured with a 1N aqueous solution of NaCl at 25 ° C., and it was [η] = 0.01 (dl / g). Comparative Examples Preparations 2 to 4 In Preparation Example 2, 60 g of a 50% by weight aqueous solution of DMAPAA sulfate and 50% by weight of N, N-dimethylaminoethyl acrylate methyl chloride quaternary salt (hereinafter referred to as DMAEA- Abbreviated as Q) aqueous solution 60
Production Example 2 using 60 g of a 50% by weight DM-C aqueous solution
Polymerization was carried out in the same manner as described above to obtain a polymer. The resulting polymer
Was measured at 25 ° C. with a 1N aqueous solution of NaCl to find that the DMAPAA sulfate polymer: [η] = 4.1, D
MAEA-Q polymer: [η] = 8.3, DM-C polymer: [η] = 7.7 (dl / c).

Example 1 (Evaluation of Coagulation Performance) Each of the polymers obtained in Production Examples 2 to 9 and Comparative Production Examples 1 to 4 using municipal sewage digested sludge having a solid content of 1.0% by weight and a pH of 7.3. A 0.2% by weight aqueous solution was added so that the polymer content was 0.3 to 2.0% by weight based on the solid content of the sludge, and the mixture was stirred with a jar tester at 200 rpm for 30 seconds.
(Capillary suction time) The sludge dewatering speed was evaluated by an evaluation device, and the moisture content of the cake and the releasability from the filter cloth were evaluated by a simple belt press device. The results are shown in Tables 1 and 2. .

[0021]

[Table 1]

[0022]

[Table 2]

From the results shown in Table 1, when the tertiary amino group-containing acrylic polymer synthesized according to the present invention is used as a sludge dehydrating agent, a conventional acrylic having a strong anion as a counter ion is used. It is clear that the polymer exhibits extremely excellent dewatering performance as compared with the polymer. In the table, regarding the evaluation of the peelability of the cake from the filter cloth, the mark ○ indicates that the cake did not adhere to the upper filter cloth, the mark も の indicates that the cake slightly adhered to the upper filter cloth, and the mark × indicates that the cake did not adhere to the upper filter cloth. Represents what adheres considerably. In the case of the conventional acrylic polymer having a strong anion as a counter ion, the flocculation and dehydration performance rapidly decreases before and after the optimum addition amount to sludge, whereas the homopolymer or copolymerized copolymer synthesized according to the present invention is used. The tertiary amino group-containing acrylic polymer has a high dehydration rate and shows stable performance in a wide range of addition amount, and the optimum addition amount is smaller than that of a conventional acrylic polymer having a strong anion as a counter ion. The peelability of the cake from the filter cloth was also good. Accordingly, it is shown that the sludge dewatering agent provided by the present invention exhibits excellent various properties against hardly dewaterable sludge generated in a large city water treatment plant.

Production Example 10 (Synthesis of Polymer) SU equipped with a temperature sensor, a pressure gauge and a carbon dioxide gas inlet tube
500 g of a 60% by weight aqueous solution of DMAPAA carbonate was added to a 1 L autoclave made of S, and the dissolved oxygen was reduced to a certain value or less with carbon dioxide gas.
1. wt%, ammonium persulfate 0.03 wt%,
2'-azobis [2- (2-imidazolin-2-yl)
Propane] dihydrochloride (VA-044 Wako Pure Chemical Industries) 0.0
5 kg by weight and adding 2 kg / cm 2 of carbon dioxide under pressure.
Polymerization was performed at room temperature. The polymerization temperature was monitored by a temperature sensor. After the polymerization temperature reached a peak, the polymer was immersed in a 50 ° C. warm bath for 3 hours to obtain a DMAPAA carbonate polymer. The obtained polymer was converted into a 3% by weight aqueous solution and decarbonated at 40 ° C. to obtain a DMAPAA polymer having a tertiary amino group. When the intrinsic viscosity of the obtained polymer was measured at 25 ° C. using a 1N aqueous solution of NaCl, [η] = 8.31 (d
1 / g).

Production Example 11 A 3% by weight aqueous solution of the DMAPAA carbonate polymer of Production Example 2 was used as a general-purpose polymer flocculant poly-dimethylaminoethyl methacrylate methyl chloride quaternary salt homopolymer (hereinafter referred to as DM-A).
This was mixed and adjusted so as to be 5% by weight based on [η] = 6.7 (dl / g). Production Example 12 A 3 wt% aqueous solution of the DMAPAA carbonate polymer of Production Example 10 was mixed and adjusted to 10 wt% with respect to the general-purpose polymer flocculant DM-C used in Production Example 11. Production Example 13 A 3% by weight aqueous solution of the DMAPAA carbonate polymer of Production Example 10 was mixed and adjusted to 20% by weight with respect to the general-purpose polymer flocculant DM-C used in Production Example 11. Production Example 14 A 3% by weight aqueous solution of the DMAPAA carbonate in Polymer of Production Example 10 was converted to a general-purpose polymer flocculant poly-dimethylaminoethyl methacrylate methyl chloride quaternary salt / acrylamide = 8/2.
Molar ratio (hereinafter abbreviated as DMAEA-Q and AAm)
[Η] = 9.29 (dl / g) was mixed and adjusted to be 5% by weight. Preparation Example 15 A general-purpose polymer flocculant DMAEA- used in Preparation Example 14 by using the 3% by weight aqueous solution of the DMAPAA carbonate in Preparation Example 10.
It was mixed and adjusted to be 10% by weight with respect to the molar ratio of Q / AAm = 8/2. Production Example 16 A general-purpose polymer flocculant DMAEA- used in Production Example 14 using the 3% by weight aqueous solution of DMAPAA carbonate in Production Example 10.
It was mixed and adjusted to be 20% by weight based on the molar ratio of Q / AAm = 8/2.

Comparative Production Example 5 The general-purpose polymer flocculant DM-C used in Production Example 11 was used in an amount of 0.2.
It adjusted so that it might become a weight% aqueous solution. Comparative Production Example 6 General-purpose polymer flocculant DMAEA-Q / used in Production Example 11
AAm = 8/2 molar ratio was adjusted to be a 0.2% by weight aqueous solution.

Example 2 The solution obtained in Production Examples 11 to 16 and Comparative Production Examples 5 and 6 was added to 100 ml of a large city sewage digested sludge (A) having a solid content of 1.2% by weight and a pH of 7.2, Per minute, so that the pure polymer content is 0.5 to 2.5% by weight,
After stirring with a jar tester at 200 rpm × 30 seconds, the floc size was measured, and the air permeability was 130 ml / cm 2 / s.
ec Cedar twill Were poured into a cylinder covered with a polyester filter cloth, and the filtrate after 90 seconds was measured with a graduated cylinder. Next, the floc was sandwiched between filter cloths of the same type, adjusted to a surface pressure of 0.9 kg / cm 2 by a compressed air pump from above, and pressed for 3 minutes. After pressing, the upper filter cloth was peeled off, the releasability was evaluated, and the cake moisture content was measured by the absolute drying method which is a known method. The measurement results are shown in Tables 3 to 5.

[0028]

[Table 3]

[0029]

[Table 4]

[0030]

[Table 5]

Example 3 A large city having a solid content of 1.7% by weight and a pH of 7.0 was replaced with 100 ml of a large city sewage digested sludge (A) having a solid content of 1.2% by weight and a pH of 7.2 in Example 2. Sewage digestion sludge (B)
Using 100 ml, the same treatment as in Example 2 was performed. Tables 6 to 8 show the measurement results.

[0032]

[Table 6]

[0033]

[Table 7]

[0034]

[Table 8]

From the results shown in Tables 3 to 8, it was clarified that the addition of a small amount of the dewatering property improver of the present invention to a general-purpose polymer flocculant significantly improved the flocculation and dewatering property for sludge.

[0036]

The sludge dehydrating agent provided by the present invention containing a tertiary amino group-containing acrylic polymer, which has been homopolymerized or copolymerized, has a conventional strong anion counter.
Compared to a sludge dehydrating agent containing acrylic polymer as an ion, it is effective with a small amount of addition, is stable against fluctuations in sludge concentration, and exhibits excellent performance of a high dehydration rate. By using in conjunction with
It is expected that sludge treatment costs can be significantly reduced by overcoming the drawbacks of conventional general-purpose flocculants.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C02F 11/00-11/20 B01D 21/01

Claims (3)

(57) [Claims] (1) wherein R 1 is a hydrogen atom or a methyl group, R 2 and R 3 are C ₁ -C ₄ alkyl groups, and n is 2-4
Indicates an integer. And / or a structural unit represented by formula (2)
(Wherein R1 is a hydrogen atom or a methyl group, R2 and R3 are C
An alkyl group of ₁ to ₄ and n represents an integer of 2 to 4. A sludge dewatering agent containing a water-soluble vinyl polymer having an intrinsic viscosity [η] of 1 dl / g or more containing 10 mol% or more of the structural unit represented by the formula (1). Embedded image Embedded image 2. Intrinsic viscosity [η] containing 1 mol% or more of a structural unit represented by Chemical Formula 1 and / or Chemical Formula 2 = 1 dl / g
Or more water-soluble vinyl polymer, of 3 (wherein, R1 is a hydrogen atom or a methyl group, R2, R3 is an alkyl group of _C 1 -C _4, n is an integer of 2-4.) Represented by An aqueous solution of an acrylic monomer having a tertiary amino group is reacted with carbon dioxide gas, wherein R 1 is a hydrogen atom or a methyl group,
R2, R3 is an alkyl group of _C 1 _{~C 4,} n is an integer of 2-4. 2. The method according to claim 1, wherein the tertiary ammonium carbonate is converted into an acrylic monomer having a tertiary ammonium carbonate and then polymerized with a vinyl monomer which can be used alone or copolymerizable.
A sludge dewatering agent as described. Embedded image Embedded image 3. A water-soluble vinyl polymer comprising a structural unit represented by Chemical Formula 1 and / or Chemical Formula 2 as an essential component and Chemical Formula 5 (wherein R4 and R5 are hydrogen or methyl groups, p is a natural number, q
Represents 0 or a natural number. A sludge dewatering agent used in combination with a polymer flocculant having a structural unit represented by the following formula: Embedded image