JP2008104908A - Amphoteric polymer flocculant and sludge-treating method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an amphoteric polymer flocculant which is not influenced by changes of properties of sludge, remarkably improves a filtration rate even if sludge of low concentration is treated, reduces a water content of a dehydrated cake, and shows excellent performance in condensation processing and dehydration processing of activated sludge and waste sludge: to provide a sludge-treating method using the flocculant. <P>SOLUTION: The amphoteric polymer flocculant is composed of a copolymer which is obtained by copolymerizing a constituent which contains a cation monomer and an anion monomer. In addition, a value of 1%ηs/1%ηB is 0.02-0.10, wherein 1%ηs represents viscosity at 25°C of a 1 mass% flocculant solution which is prepared by dissolving the amphoteric polymer flocculant in 0.2 N sodium chloride aqueous solution, and 1 %ηB represents viscosity at 25°C of a 1 mass% flocculant solution which is prepared by dissolving the amphoteric polymer flocculant in ion-exchange water. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an amphoteric polymer flocculant and a sludge treatment method using the same, and more particularly to an amphoteric polymer flocculant exhibiting excellent filtration performance with respect to a belt press type concentrator or dehydrator.

Wastewater treatment facilities such as sewage treatment plants, paper industry, food industry, etc., purify wastewater by methods such as sedimentation separation and biological treatment. The sludge generated during such purification treatment is usually dewatered by a screw decanter, a belt press or the like to obtain a dehydrated cake having a low water content, and then incinerated.
In addition, for the purpose of efficiently performing sludge dewatering, a method of flocating sludge particles by adding a polymer flocculant to sludge in advance and mixing is widely used. As the polymer flocculant, a cationic polymer flocculant is conventionally known.

Furthermore, in recent years, an increasing number of facilities have introduced biological denitrification and dephosphorization methods for the purpose of improving the quality of purified water and measures for eutrophication.
Nitrogen is finally converted into nitrogen gas and discharged out of the system in the process of biological denitrification. On the other hand, phosphorus is taken into activated sludge and then discharged out of the system as surplus sludge. In general, the excess sludge is mixed with primary sludge, dehydrated after concentration and storage.
However, with the passage of time during concentration and storage, phosphorus was re-released from the sludge and returned to the system. Therefore, in order to prevent re-release of phosphorus, a method of directly dehydrating activated sludge or excess sludge, a method of dehydrating continuously after concentration, and the like have been proposed.

However, the conventional cationic polymer flocculant has not obtained a sufficient treatment effect. One of the causes is that the cationic polymer flocculant is used for concentration and dehydration due to sludge properties such as low concentration, high loss on ignition (hereinafter referred to as “VTS”), and low colloidal charge. It is difficult to produce suitable large and dense aggregated flocs.
In addition, due to an increase in the amount of sludge generated, deterioration of sludge properties, etc., the cationic polymer flocculant has a limit in the amount of sludge treated and the filtration rate, making it difficult to obtain a dehydrated cake having a sufficiently low water content.

Therefore, various amphoteric polymer flocculants that improve both the drawbacks of these conventional cationic polymer flocculants and have both cationic and anionic properties have been proposed (see, for example, Patent Documents 1 to 3). .
Patent Document 1 proposes an amphoteric polymer flocculant having a tertiary amine.
Patent Document 2 proposes an amphoteric polymer flocculant having a quaternary ammonium salt.
The amphoteric polymer flocculants described in Patent Documents 1 and 2 are superior in flocculence compared to conventional cationic polymer flocculants and can form large flocs. In particular, the amphoteric polymer flocculant of Patent Document 2 was excellent in storage stability when it was made into a powder product.
Patent Document 3 proposes an amphoteric polymer flocculant having two types of quaternary ammonium salts. The amphoteric polymer flocculant was excellent in the amount of flocculant added, the flocculence, the storage stability of the powder product, the solubility, and the like.
JP-A-62-205112 JP-A-53-149292 JP 7-256299 A

However, the amphoteric polymer flocculant described in Patent Document 1 is susceptible to changes in properties such as sludge pH value and sludge concentration, and stable treatment is difficult.
Moreover, in the amphoteric polymer flocculant described in Patent Document 2, the amount of amphoteric polymer flocculant required is large and the sludge filtration rate is slow.
Furthermore, in the amphoteric polymer flocculant described in Patent Document 3, when sludge having a low concentration such as activated sludge and excess sludge is treated, the filtration rate is slow, and the moisture content of the dehydrated cake may be high.

  The present invention has been made in view of the above circumstances, is not affected by changes in the properties of sludge, and dramatically improves the filtration rate even when processing low-concentration sludge, and the moisture content of the dewatered cake It is an object of the present invention to provide an amphoteric polymer flocculant that exhibits excellent filtration performance for concentration treatment and dewatering treatment of activated sludge and excess sludge, and a sludge treatment method using the same.

As a result of intensive studies to solve the above problems, the present inventors have found that the viscosity of the amphoteric polymer flocculant is involved in improving the filtration rate and reducing the moisture content of the dehydrated cake, leading to the present invention. It was.
That is, the amphoteric polymer flocculant of the present invention is an amphoteric polymer flocculant composed of a copolymer obtained by copolymerizing components containing a cationic monomer and an anionic monomer, and contains 1% ηs. The amphoteric polymer flocculant having a value of / 1% ηB of 0.02 to 0.10.
1% ηs is a viscosity at 25 ° C. when an amphoteric polymer flocculant is dissolved in a 0.2 N sodium chloride aqueous solution to form a 1 mass% flocculant solution.
1% ηB is a viscosity at 25 ° C. when an amphoteric polymer flocculant is dissolved in ion-exchanged water to obtain a 1 mass% flocculant solution.
Further, the cationic monomer has a quaternary ammonium salt of a dialkylaminoalkyl methacrylate monomer, and the content of the quaternary ammonium salt of a dialkylaminoalkyl acrylate monomer is 5 in 100 mol% of the constituent components. It is preferable that it is less than mol%.
Furthermore, the sludge treatment method of the present invention is characterized in that the amphoteric polymer flocculant is added to the sludge for tempering, and the concentration treatment or dehydration treatment is performed using a belt press type concentrator or dehydrator. .
The sludge is preferably activated sludge or excess sludge.

  According to the present invention, it is not affected by changes in sludge properties, and even when processing low-concentration sludge, the filtration rate is dramatically improved, the moisture content of the dehydrated cake is reduced, activated sludge and surplus It is possible to provide an amphoteric polymer flocculant that exhibits excellent filtration performance for sludge concentration treatment and dehydration treatment, and a sludge treatment method using the same.

The present invention will be described in detail below.
The amphoteric polymer flocculant of the present invention comprises a copolymer obtained by copolymerizing constituents containing a cationic monomer and an anionic monomer.

  The cationic monomer is a quaternary compound represented by the following general formula (1) such as a halogenated alkyl adduct such as methyl chloride adduct of dialkylaminoalkyl methacrylate, an aryl halide adduct such as benzyl chloride adduct, etc. It preferably has an ammonium salt. Examples of the dialkylaminoalkyl methacrylate include dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, diethylamino-2-hydroxypropyl methacrylate and the like. Of these, dimethylaminoethyl methacrylate is preferred.

In formula (1), R ¹ is an alkylene group having 2 to 3 carbon atoms. R ² and R ³ are alkyl groups having 1 to 2 carbon atoms, and may be the same or different. R ⁴ is an alkyl group having 1 to 2 carbon atoms or a benzyl group. X ¹ is an anion such as a halide.

  Further, the cationic monomer is represented by the following general formula (2), such as a halogenated alkyl adduct such as methyl chloride adduct of dialkylaminoalkyl acrylate, an aryl halide adduct such as benzyl chloride adduct, etc. A quaternary ammonium salt may be included. Examples of the dialkylaminoalkyl acrylate include dimethylaminoethyl acrylate, diethylaminoethyl acrylate, diethylamino-2-hydroxypropyl acrylate, and the like. Of these, dimethylaminoethyl acrylate is preferred.

In Formula (2), R ⁵ is an alkylene group having 2 to 3 carbon atoms. R ⁶ and R ⁷ are each an alkyl group having 1 to 2 carbon atoms and may be the same or different. R ⁸ is an alkyl group having 1 to 2 carbon atoms or a benzyl group. X ² is an anion such as halide.

  Further, the cationic monomer may contain other components. Other components include dialkylaminoalkyl (meth) acrylate hydrochlorides such as dimethylaminoethyl (meth) acrylate, tertiary salts such as sulfates; dialkyl (meth) acrylamides such as N, N-dimethyl (meth) acrylamide And quaternary ammonium salts such as halogenated alkyl adducts such as methyl chloride adduct and halogenated aryl adducts such as benzyl chloride adduct.

  These cationic monomers may be used alone or in combination of two or more. As for content of a cationic monomer, 20-80 mol% is preferable in 100 mol% of structural components, and 30-60 mol% is more preferable. When the content of the cationic monomer is less than the above range, a large aggregated floc is generated, but the water content of the dehydrated cake is increased. On the other hand, if the content is larger than the above range, small aggregated flocs are generated, resulting in poor filtration rate.

When the cationic monomer contains a quaternary ammonium salt of dialkylaminoalkyl acrylate, the content of the quaternary ammonium salt of dialkylaminoalkyl acrylate is preferably less than 5 mol%, more preferably in 100 mol% of the constituent components. Content is 0.1-2 mol%. When the content of the quaternary ammonium salt of dialkylaminoalkyl acrylate is more than the above range, coarse flocculation flocs are produced when added to sludge and excellent cohesiveness is exhibited, but the filtration rate becomes insufficient.
When the cationic monomer contains other components, the total content of the quaternary ammonium salt of the dialkylaminoalkyl acrylate and the other components is less than 5 mol% in 100 mol% of the constituent components. desirable.

 Examples of the anionic monomer include (meth) acrylic acid and alkali metal salts or ammonium salts thereof such as sodium salt; maleic acid and the like and alkali metal salts or ammonium salts thereof; acrylamido-2-methylpropanesulfonic acid and Examples include alkali metal salts or ammonium salts such as sodium salts; alkali metal salts or ammonium salts such as vinylsulfonic acid and sodium salts thereof. Among these, (meth) acrylic acid represented by the following general formula (3) is preferable.

  These anionic monomers may be used individually by 1 type, and may use 2 or more types together. The content of the anionic monomer is preferably from 1 to 15 mol%, more preferably from 3 to 10 mol%, in 100 mol% of the constituent components. If the content of the anionic monomer is less than the above range, small aggregated flocs are generated, resulting in poor filtration rate. On the other hand, when the content is larger than the above range, the amount of amphoteric polymer flocculant added increases, and the water content of the dehydrated cake increases.

In the present invention, a nonionic monomer may be used for copolymerization of the copolymer. By using a nonionic monomer, cationic and anionic ionic strength can be adjusted.
Nonionic monomers include (meth) acrylamide, styrene, acrylonitrile, vinyl acetate, alkyl acrylate, and the like. Among these, (meth) acrylamide represented by the following general formula (4) is preferable.

  These nonionic monomers may be used individually by 1 type, and may use 2 or more types together. The content when the nonionic monomer is contained in the constituent component is preferably 5 to 80 mol%, more preferably 35 to 65 mol%, in 100 mol% of the constituent component. If the content of the nonionic monomer is less than the above range, small aggregated flocs are generated, resulting in a poor filtration rate. On the other hand, when the content is larger than the above range, the moisture content of the dehydrated cake increases.

  The amphoteric polymer flocculant of the present invention comprises a copolymer obtained by copolymerizing the above-described constituent components. Examples of the polymerization method include precipitation polymerization, bulk polymerization, dispersion polymerization, aqueous solution polymerization, and the like, but are not particularly limited thereto.

The amphoteric polymer flocculant has a value of 1% ηs / 1% ηB of 0.02 to 0.10, preferably 0.03 to 0.08, and more preferably 0.03 to 0.06. By setting the value of 1% ηs / 1% ηB within the above range, even when processing sludge with a low concentration, a large and dense coagulated floc is formed. Excellent effect in reducing the moisture content of In particular, when sludge is dewatered by a belt press type dehydrator described later, if the value of 1% ηs / 1% ηB is larger than the above range, a large coagulated floc is obtained, but the density becomes coarse (coarse and coarse). Become). On the other hand, when the value of 1% ηs / 1% ηB is smaller than the above range, the aggregation flocs become small and the filtration rate becomes slow. In addition, even when the aggregation floc becomes coarse, the filtration rate tends to be slow.
Here, 1% ηs is a viscosity at 25 ° C. when an amphoteric polymer flocculant is dissolved in a 0.2 N sodium chloride aqueous solution to form a 1 mass% flocculant solution.
1% ηB is a viscosity at 25 ° C. when an amphoteric polymer flocculant is dissolved in ion-exchanged water to obtain a 1 mass% flocculant solution.

In addition, the values of 1% ηs and 1% ηB of the amphoteric polymer flocculant are adjustments of the molecular weight, ionic ratio, molecular weight distribution, production method, composition distribution, hydrophilicity / hydrophobicity degree, etc. of the amphoteric polymer flocculant Can be controlled by.
For example, when the copolymerization ratio of the quaternary ammonium salt of dialkylaminoalkyl acrylate is increased, the values of 1% ηs and 1% ηB tend to increase. On the other hand, when the molecular weight of the amphoteric polymer flocculant is decreased, the values of 1% ηs and 1% ηB tend to decrease.

  As the sludge treatment method of the present invention, known concentration treatment methods and dehydration treatment methods can be used. That is, the amphoteric polymer flocculant described above is added to sludge to form a floc floc, and the sludge is concentrated with a concentrator and then dehydrated or directly with a dehydrator to create a dehydrated cake. Thus, the sludge treatment can be completed. Furthermore, the sludge can be finally disposed of by, for example, incinerating the obtained dehydrated cake.

The amount of amphoteric polymer flocculant added depends on the quality and concentration of the sludge and cannot be generally specified, but as a rough guideline, it is preferably 0.1% or more, more preferably 0.2% or more based on the sludge solids. preferable. In the present invention, there is little adverse effect on the filterability due to the excessive addition of the amphoteric polymer flocculant, and the upper limit of the amount of amphoteric polymer flocculant added is not particularly limited. 1.0% or less is preferable and 0.6% or less is more preferable.
In addition, an amphoteric polymer flocculant may be used individually by 1 type, and may use 2 or more types together.
In the present invention, when an amphoteric polymer flocculant is used, a solid acid may be used in combination as appropriate in order to improve water solubility. Examples of the solid acid include sulfamic acid and acidic sodium sulfite.

Examples of the concentrating device include a belt press type concentrator and a screw decanter. A belt press type concentrator is preferable depending on the characteristics of filtration speed.
Examples of the dehydrating device include a screw press type dehydrator, a belt press type dehydrator, a filter press type dehydrator, a screw decanter, and the like. Is preferred.

  Examples of sludge that can be treated in the present invention include activated sludge, surplus sludge, digested sludge, agglomerated sludge, or mixed sludge generated from sewage treatment facilities and biological wastewater treatment facilities for organic wastewater generated in the chemical and food industries. it can. In particular, it is effective for activated sludge and excess sludge having a low sludge concentration and difficult to dewater.

  As described above, according to the present invention, by specifying the value of 1% ηs / 1% ηB of the amphoteric polymer flocculant, low-concentration activated sludge or surplus which has been difficult to concentrate and dehydrate by the conventional method. Also in the sludge treatment, the filtration rate is excellent, the concentrating property and the dewatering property are improved, and the efficient sludge treatment becomes possible.

  Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.

In the following Examples and Comparative Examples, amphoteric polymer flocculants and cationic polymer flocculants (hereinafter sometimes referred to as “polymer flocculants”) are prepared by dissolving the polymers shown in Table 1 in water. A 0.3% by mass aqueous solution was used.
In addition, each viscosity of each polymer flocculant was calculated | required as follows. The results are shown in Table 1.

(Measurement of 1% ηB)
495.0 g of ion-exchanged water was collected in a 500 ml glass beaker. Next, using a dissolving apparatus 10 as shown in FIG. 1, 5.00 g of the polymer flocculant was added little by little while stirring at a rotation speed of 280 rpm so as not to make mamako. Stirring was continued for 4 hours after adding the polymer flocculant to prepare a 1% by weight flocculant solution.
The viscosity of the obtained 1% by mass flocculant solution was measured using a B-type viscometer (manufactured by Tokyo Keiki Co., Ltd.) at a rotation speed of 6 rpm.
The melting apparatus 10 includes a variable stirrer 11 and a telescopic stand 12. The variable stirrer 11 includes, for example, a stirring shaft 11a having a diameter of 7.5 to 7.9Φ, a width W of 45 mm, and a thickness T. Is provided with two stirring blades 11b (the distance D between the stirring blades 11b is 35 mm).

(Measurement of 1% ηs)
5.84 g of sodium chloride was added to the previously obtained 1% by mass flocculant solution, and the mixture was stirred for 30 minutes at a rotational speed of 280 rpm in the dissolution apparatus 10 to dissolve the sodium chloride. Was measured at a rotational speed of 6 rpm.

In Table 1, the abbreviations of the constituent components represent the monomers shown below.
DMC: dimethylaminoethyl methacrylate / methyl chloride quaternary salt.
DME: dimethylaminoethyl acrylate / methyl chloride quaternary salt.
DMZ: Dimethylaminoethyl methacrylate sulfate.
AAm: acrylamide.
AA: acrylic acid.
The above DMC and DME are quaternary ammonium salts of cationic monomers, DMZ is a tertiary salt of cationic monomers, AAm is a nonionic monomer, and AA is an anionic monomer.

<Measurement method>
In the following examples and comparative examples, each characteristic was measured by the following method.
TS concentration (evaporation residue): Measured based on a standard method (edited by Japan Sewerage Association, “Sewerage Test Method, Vol. 1997, p. 296-297)”.
VTS value (loss on ignition): Measured based on a regular method (edited by the Japan Sewerage Association, “Sewerage Test Method Vol. 1997 edition” p297).
Aggregated floc average particle diameter: measured by visual observation.
Filtration rate: The amount of filtrate for 5 seconds after the start of filtration was measured as the filtration rate when the sludge after agitation was filtered with a nutsch with a filter cloth.
Moisture content of dehydrated cake: measured based on a conventional method (edited by the Japan Sewerage Association, “Sewerage Test Method, Vol. 1997, p. 296-297)”.
Concentrated sludge concentration: Measured based on a conventional method in the same manner as TS concentration (evaporation residue).

<Examples 1-6>
A test of dehydration treatment was performed using sewage surplus sludge 1 (pH: 6.8, TS concentration: 0.60%, VTS: 67.7%).
First, 300 ml of the above sewage surplus sludge 1 is collected in a 500 ml beaker, and the amphoteric polymer flocculant of the type shown in Table 2 is added in an amount shown in Table 2, and the rate is about 100 times per minute using a spatula. The mixture was stirred and mixed for 20 seconds to form aggregated floc.
The average particle size and filtration rate of the agglomerated floc were measured.
After 1 minute from the start of filtration, the residue (concentrated sludge) on the filter cloth was sandwiched between the filter cloths, press dehydrated at a pressure of 0.1 Map to create a dehydrated cake, and the moisture content of the dehydrated cake was determined. The test results are shown in Table 2.

<Comparative Examples 1-5>
Except that the amphoteric polymer flocculant was changed to the type of polymer flocculant shown in Table 2, a dehydration test was conducted in the same manner as in Examples 1 to 6, and each characteristic was measured. The results are shown in Table 2.

As is clear from Table 2, in Examples 1 to 5, all of the average particle size was large, and a floc floc having an excellent filtration rate was formed. The moisture content of the dehydrated cake was low, and good results were obtained. In Example 6 where the DME content was 8 mol%, a slightly coarse aggregated floc was formed, and the filtration rate and the moisture content of the dehydrated cake were slightly insufficient compared to Examples 1-5. .
On the other hand, in Comparative Examples 1 and 2 using an amphoteric polymer flocculant having a value of 1% ηs / 1% ηB of 0.18, coarse flocculated flocs were formed, and the filtration rate and the moisture content of the dehydrated cake were examples. All were inferior to 1-6. Further, in Comparative Example 3 using an amphoteric polymer flocculant having a value of 1% ηs / 1% ηB of 0.018, the average particle size of the flocculated floc is small, and the filtration rate and the moisture content of the dehydrated cake are in Example 1. It was inferior to ~ 6. Furthermore, in Comparative Examples 4 and 5 using a cationic polymer flocculant, the filtration rate and the moisture content of the dehydrated cake were inferior to those of Examples 1 to 6.

<Examples 7 to 9>
A test of dehydration treatment was performed using sewage surplus sludge 2 (pH: 6.5, TS concentration: 1.03%, VTS: 39.8%).
Test of dehydration treatment in the same manner as in Examples 1 to 6 except that 300 ml of the sewage surplus sludge 2 was collected in a 500 ml beaker and the amount of amphoteric polymer flocculant of the type shown in Table 3 was added as shown in Table 3. And each characteristic was measured. The results are shown in Table 3.

<Comparative Examples 6 and 7>
Except that the amphoteric polymer flocculant was changed to the type of polymer flocculant shown in Table 3, a dehydration test was conducted in the same manner as in Examples 1 to 6, and each characteristic was measured. The results are shown in Table 3.

As is clear from Table 3, in Examples 7 to 9, all of the average particle diameters were large, flocculent flocs having excellent filtration speed were formed, the moisture content of the dehydrated cake was low, and good results were obtained.
On the other hand, in Comparative Example 6 using an amphoteric polymer flocculant having a value of 1% ηs / 1% ηB of 0.18, coarse flocculated flocs were formed, and the filtration rate and the moisture content of the dehydrated cake were in Examples 7 to. All were inferior to 9. Moreover, in the comparative example 7 using a cationic polymer flocculant, the filtration rate and the moisture content of the dewatering cake were inferior compared with Examples 1-6.

<Examples 10 and 11>
Concentration treatment was tested using food surplus sludge (pH: 6.8, TS concentration: 0.52%, VTS: 76.7%).
First, 300 ml of the above food surplus sludge is collected in a 500 ml beaker, the amount of amphoteric polymer flocculant of the type shown in Table 4 is added in the amount shown in Table 4, and 20 times at a rate of about 100 times per minute using a spatula. The mixture was stirred and mixed for 2 seconds to form aggregated floc.
The average particle size and filtration rate of the agglomerated floc were measured.
After 1 minute from the start of filtration, the residue (concentrated sludge) on the filter cloth was collected and its concentration was determined. The results are shown in Table 4.

<Comparative Examples 8 and 9>
Concentration tests were conducted in the same manner as in Examples 10 and 11 except that the amphoteric polymer flocculant was changed to the type of polymer flocculant shown in Table 4, and each characteristic was measured. The results are shown in Table 4.

As is clear from Table 4, in Examples 10 and 11, the filtration rate was excellent, the concentration of concentrated sludge was high, and good results were obtained.
On the other hand, in Comparative Example 8 using an amphoteric polymer flocculant having a value of 1% ηs / 1% ηB of 0.18, coarse aggregated flocs were formed, and the filtration rate was inferior to Examples 10 and 11, The concentration of concentrated sludge was low. Moreover, in the comparative example 9 using a cationic polymer flocculant, the filtration rate was inferior compared with Examples 10 and 11, and the density | concentration of concentrated sludge was low.

It is the schematic which shows an example of the melt | dissolution apparatus used for the measurement of 1% (eta) s and 1% (eta) B.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Dissolution apparatus 11 Variable stirrer 11a Stirring shaft 11b Stirring blade 12 Telescopic stand

Claims (4)

An amphoteric polymer flocculant composed of a copolymer obtained by copolymerizing components containing a cationic monomer and an anionic monomer,
An amphoteric polymer flocculant having a value of 1% ηs / 1% ηB of 0.02 to 0.10.
1% ηs is a viscosity at 25 ° C. when an amphoteric polymer flocculant is dissolved in a 0.2 N sodium chloride aqueous solution to form a 1 mass% flocculant solution.
1% ηB is a viscosity at 25 ° C. when an amphoteric polymer flocculant is dissolved in ion-exchanged water to obtain a 1 mass% flocculant solution.   The cationic monomer has a quaternary ammonium salt of a dialkylaminoalkyl methacrylate monomer, and the content of the quaternary ammonium salt of a dialkylaminoalkyl acrylate monomer is 5 mol% in 100 mol% of the constituent components. The amphoteric polymer flocculant according to claim 1, wherein   A method for treating sludge, characterized in that the amphoteric polymer flocculant according to claim 1 or 2 is added to a sludge for tempering, and a concentration treatment or a dehydration treatment is performed using a belt press type concentrator or a dehydrator. . The method of treating sludge according to claim 3, wherein the sludge is activated sludge or excess sludge.

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