JP5232680B2 - Method for treating treated water containing inorganic sludge - Google Patents

Description

  The present invention relates to a method for treating water to be treated containing inorganic sludge, such as mud generated in civil engineering and construction work.

  Muddy water generated in civil engineering / construction work contains a lot of water and has high fluidity. Therefore, in that state, handling is poor and it takes a large amount of money to carry out. For this reason, usually, muddy water is dehydrated and volume-reduced at civil engineering / construction work sites to reduce carry-out costs.

The muddy water is treated by adding a dehydrating agent containing a flocculant to the mud and aggregating the inorganic sludge. The method to use is common.
However, the muddy water generated by the shield method often contains a mud adjuster (such as bentonite) that contains water and easily swells, so dehydration is often difficult.

The following method has been proposed as a method for treating muddy water containing bentonite (hereinafter referred to as bentonite muddy water).
(1) A method using a dehydrating agent comprising a cationic polymer flocculant, an anionic polymer flocculant, and a water-soluble salt (calcium chloride, magnesium chloride, etc.) (Patent Document 1).
(2) After adding a water-soluble metal salt (magnesium chloride, calcium chloride, etc.) to bentonite mud, it consists of a cationic polymer flocculant, an anionic polymer flocculant, and a water-soluble salt (sodium sulfate, etc.). A method of adding a dehydrating agent (Patent Document 2).
(3) A method of adding an anionic polymer flocculant after adding a cationic polymer flocculant to bentonite mud (Patent Document 3).

However, in the methods (1) and (2), in order to agglomerate inorganic sludge, it is necessary to add a large amount of a dehydrating agent, and the processing cost is high.
In the method (3), since the cationic polymer flocculant and the anionic polymer flocculant are added separately, the number of steps is increased and time is required.

Japanese Patent Laid-Open No. 5-38404 JP 2001-49981 A Japanese Patent Publication No. 55-16718

  The present invention provides a method that can easily treat water to be treated containing inorganic sludge at low cost.

The treatment method of water to be treated containing inorganic sludge according to the present invention includes a step of adding a dehydrating agent to water to be treated containing inorganic sludge and aggregating the inorganic sludge to obtain treated water containing aggregates. In the method for treating water to be treated containing sludge, the method further comprises adjusting the pH of the water to be treated containing inorganic sludge to 7 to 11 in advance, and the water to be treated containing inorganic sludge has a mud adjuster. The muddy water is used , and the dehydrating agent is obtained by dissolving a basic compound and the following amphoteric polymer flocculant in water.
Amphoteric polymer flocculant: a structural unit derived from the monomer (a) having a carboxy group, and a monomer represented by the following formula (1) (b1) or the following formula (2) A polymer having a structural unit derived from the body (b2).

In the formula, R ¹ is a hydrogen atom or a methyl group, R ² is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ³ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. and a, ^{R 4} is an alkyl group or a benzyl group having 1 to 4 carbon atoms, Z ^- is Cl ^- or 1 / _2SO ^{4 2-.}

It is preferable that the method for treating water to be treated containing inorganic sludge according to the present invention further includes a step of dehydrating the treated water containing the aggregates .

  The amphoteric polymer flocculant contains 5 to 20 mol% of the structural unit derived from the monomer (a) and 2 of the structural unit derived from the monomer (b1) or the monomer (b2). It is preferable that it is a polymer which has -20 mol% and 60-93 mol% of the structural unit derived from another monomer (c).

  According to the method for treating water to be treated containing inorganic sludge according to the present invention, the water to be treated containing inorganic sludge can be easily treated at low cost.

It is the schematic which shows an example of the processing system used for the processing method of the to-be-processed water containing inorganic sludge of this invention.

<Treatment of treated water containing inorganic sludge>
FIG. 1 is a schematic diagram showing an example of a treatment system used in the treatment method of water to be treated containing inorganic sludge according to the present invention. The treatment system 10 is a mud storage tank 12 for storing treated water containing inorganic sludge, and a dehydrating agent is added to the treated water containing inorganic sludge, and the inorganic sludge is aggregated to obtain treated water containing aggregates. A reaction tank 14, a dehydrator 16 that dehydrates treated water containing aggregates, and a dehydrant tank 18 that prepares and stores a dehydrating agent to be supplied to the aggregation reaction tank 14 are provided.

Treatment of water to be treated containing inorganic sludge using the treatment system 10 is performed through the following steps (I) to (III).
(I) The process of adjusting the pH of the to-be-processed water containing inorganic sludge to 7-11 in the mud storage tank 12 grade | etc., As needed.
(II) A step of adding a dehydrating agent to the water to be treated containing inorganic sludge in the agglomeration reaction tank 14 to agglomerate the inorganic sludge to obtain treated water containing the aggregate.
(III) A step of dehydrating treated water containing aggregates in the dehydrator 16.

(Process (I))
Since the reaction between the amphoteric polymer flocculant and the inorganic sludge proceeds efficiently by adjusting the pH of the water to be treated containing inorganic sludge to 7 to 11 in advance in the mud storage tank 12 or the like, step (II) The amount of dehydrating agent added in can be further reduced. The pH is more preferably 9-11.
For adjusting the pH, an acidic compound (sulfuric acid, hydrochloric acid, etc.) or a basic compound (calcium hydroxide, magnesium hydroxide, etc.) may be used.

Examples of treated water containing inorganic sludge include muddy water, shield muddy water, and dredged muddy water generated in civil engineering and construction work.
Mud generated in civil engineering and construction works is a slurry-like material generated by the underground continuous wall method, mud shield method, cast-in-place pile method, etc., and examples of the mud include bentonite mud, polymer mud, silt mud, etc. Can be mentioned.
The processing method of the to-be-processed water containing inorganic sludge of this invention is suitable for the treatment of the mud containing the mud modifier (bentonite, CMC, etc.) with which inorganic sludge is hard to aggregate.

(Process (II))
In the aggregation reaction tank 14, a dehydrating agent is added to the water to be treated containing inorganic sludge, and the inorganic sludge is aggregated to obtain treated water containing aggregates.
Examples of the agglomeration reaction tank 14 include a biaxial paddle mixer, a mixing tank composed of a circular / rectangular tank and various rotary blades, a rotary drum type, and a static mixer.
The dehydrating agent is an aqueous solution in which a basic compound and an amphoteric polymer flocculant are dissolved in water.

The addition amount of the dehydrating agent is preferably such that the addition rate of the amphoteric polymer flocculant is 300 to 3000 ppm in the water to be treated.
The concentration of the amphoteric polymer flocculant in the dehydrating agent (100% by mass) is preferably 0.01 to 1.0% by mass.

The basic compound is used to make the pH of water alkaline so that the amphoteric polymer flocculant can be dissolved in water.
Examples of the basic compound include sodium hydroxide and potassium hydroxide.
The pH of the water before dissolving the amphoteric polymer flocculant is preferably 9-13.

  The amphoteric polymer flocculant is composed of a structural unit derived from the monomer (a) having a carboxy group and a monomer (b1) represented by the following formula (1) or a single unit represented by the following formula (2). A structural unit derived from the monomer (b2) (hereinafter, the monomer (b1) and the monomer (b2) are collectively referred to as the monomer (b)), and the monomer (a ) And a structural unit derived from another monomer (c) excluding the monomer (b).

In the formula, R ¹ is a hydrogen atom or a methyl group, R ² is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ³ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. and a, ^{R 4} is an alkyl group or a benzyl group having 1 to 4 carbon atoms, Z ^- is Cl ^- or 1 / _2SO ^{4 2-.}

  Examples of the monomer (a) include (meth) acrylic acid, (meth) acrylate, crotonic acid, crotonic acid salt, itaconic acid, itaconic acid salt, maleic acid, maleate, etc. From the viewpoint of being high and relatively inexpensive, (meth) acrylic acid and (meth) acrylate are preferable. A monomer (a) may be used individually by 1 type, and may use 2 or more types together.

  As the monomer (b), tertiary salt (hydrochloric acid salt of N, N-dialkylaminoalkyl (meth) acrylamide (N, N-dimethylaminopropyl (meth) acrylamide) etc.), quaternary ammonium salt (Halogenated alkyl adducts (N, N-dialkylaminoalkyl (meth) acrylamide methyl chloride adducts, etc.), halogenated aryl adducts (N, N-dialkylaminoalkyl (meth) acrylamide benzyl chloride adducts, etc.) N, N-dimethylaminopropylacrylamide hydrochloride having a tertiary amine exhibiting dissociation at pH: 10.3 is preferable. A monomer (b) may be used individually by 1 type, and may use 2 or more types together.

  The other monomer (c) is not particularly limited as long as it is a monomer that dissolves in water, and (meth) acrylamide which is a water-soluble nonionic monomer is preferable.

  5-20 mol% is preferable in all the structural units (100 mol%), and, as for the ratio of the structural unit derived from a monomer (a), 10-15 mol% is more preferable. If the structural unit derived from the monomer (a) is 5 mol% or more, the balance with the cationic group of the structural unit derived from the monomer (b) becomes good, and a strong aggregate (floc) is formed. Can be formed. If the structural unit derived from the monomer (a) is 20 mol% or less, it is difficult to form an ion complex with the cationic group of the structural unit derived from the monomer (b). Easy to dissolve in water.

  2-20 mol% is preferable in all the structural units (100 mol%), and, as for the ratio of the structural unit derived from a monomer (b), 3-15 mol% is more preferable. If the structural unit derived from the monomer (b) is 2 mol% or more, the dewatering effect of muddy water having a relatively high pH is easily exhibited. If the structural unit derived from the monomer (b) is 20 mol% or less, the ion balance with the anionic group of the structural unit derived from the monomer (a) becomes good, and a strong aggregate (floc) Can be formed.

The proportion of the structural unit derived from the other monomer (c) is preferably 60 to 93% by mole, more preferably 70 to 90% by mole in all the structural units (100% by mole). If the structural unit derived from the other monomer (c) is within this range, the amount of ions of the anionic group and the cationic group introduced into the amphoteric polymer flocculant becomes an appropriate amount, and a strong aggregate (Floc) can be formed.
The ratio of the structural unit derived from each monomer is calculated from the charged amount of each monomer when producing the polymer.

The amphoteric polymer flocculant is obtained by copolymerizing the monomer (a), the monomer (b) and, if necessary, another monomer (c).
Examples of the polymerization method include the following methods (i) and (ii), and the method (ii) is preferable.
(I) An aqueous solution adiabatic polymerization method in which an aqueous monomer solution in which each monomer is dissolved in water is copolymerized using an initiator (a redox initiator, an azo-based initiator, etc.) that generates radicals by heat. .
(Ii) An aqueous solution photopolymerization method in which a monomer aqueous solution in which each monomer is dissolved in water is formed into a uniform sheet and copolymerized by irradiation with visible light or ultraviolet light using a photoinitiator.
In the method (ii), a hydrogel polymer (that is, a hydrous product of an amphoteric polymer flocculant) is usually obtained.

Examples of the photoinitiator include 2-hydroxy-2-methyl-1-phenyl-1-propanone (manufactured by Ciba, DAROCUR 1173).
The addition amount of the photoinitiator is preferably 0.001 to 0.1 parts by mass with respect to 100 parts by mass of the monomer aqueous solution. If the addition amount of the photoinitiator is 0.001 part by mass or more, a sufficient copolymerization rate and copolymerization rate can be secured, and productivity and quality can be improved. If the addition amount of the photoinitiator is 0.1 parts by mass or less, runaway copolymerization and quality deterioration of the copolymer can be prevented.

When each monomer is copolymerized, a chain transfer agent may be added as necessary. Examples of the chain transfer agent include hypophosphorous acid and phosphonic acid, and hypophosphorous acid is preferred from the viewpoint of easy chain transfer.
The addition amount of the chain transfer agent is preferably 0.001 to 1 part by mass with respect to 100 parts by mass of the monomer aqueous solution. If the addition amount of the chain transfer agent is 0.001 part by mass or more, the production of a water-insoluble crosslinked copolymer can be suppressed. If the addition amount of the chain transfer agent is 1 part by mass or less, a sufficient molecular weight can be ensured, so that sufficient aggregation dehydrating properties can be obtained particularly in the use of a polymer flocculant that requires a high molecular weight.
The amount of crosslinked copolymer insoluble in water is determined by filtering an aqueous solution of an amphoteric polymer flocculant with a sieve having a diameter of 20 cm and an 80 mesh and quantifying the insoluble matter remaining on the sieve. be able to.

  The salt viscosity when the amphoteric polymer flocculant is an aqueous solution having a concentration of 0.5% by mass (hereinafter, the aqueous solution of the amphoteric polymer flocculant is referred to as a polymer aqueous solution) is usually 5 to 200 mPa · s, 10 to 100 mPa · s is preferable. If the salt viscosity when the 0.5 mass% polymer aqueous solution is 5 mPa · s or more, sufficient cohesiveness can be obtained particularly in the use of a polymer flocculant requiring high viscosity. If the salt viscosity when it is 0.5 mass% polymer aqueous solution is 200 mPa * s or less, the production | generation of the crosslinked copolymer insoluble in water can be suppressed.

The salt viscosity is a viscosity at 25 ° C. measured with a B-type viscometer when an amphoteric polymer flocculant is dissolved in a 4% by mass sodium chloride aqueous solution to form a 0.5% by mass polymer aqueous solution.
The salt viscosity of the amphoteric polymer flocculant can be controlled by adjusting the molecular weight, ionic ratio, molecular weight distribution, production method, composition distribution, hydrophilicity / hydrophobicity degree, etc. of the amphoteric polymer flocculant. For example, the value of salt viscosity tends to increase as the molecular weight increases or the ionic ratio decreases. On the other hand, the lower the molecular weight, the higher the ionic ratio, the lower the value of salt viscosity.

(Process (III))
In the dehydrator 16, the treated water containing aggregates is dehydrated to obtain a dewatered cake of inorganic sludge.
Examples of the dehydrator include a filter press type dehydrator, a screw press type dehydrator, a vacuum dehydrator, a belt press type dehydrator, a centrifugal dehydrator, and the like, because a dehydrated cake having a relatively low water content can be obtained. A filter press dehydrator or a screw press dehydrator is preferred.

The water content of the dehydrated cake is preferably 30 to 40% by mass.
Dehydrated cake can be reused as backfill and embankment.
The filtered water discharged from the dehydrator 16 is discarded after being neutralized with an acidic compound.

In the treatment method of the water to be treated containing inorganic sludge according to the present invention described above, since a dehydrating agent in which a basic compound and a specific amphoteric polymer flocculant are dissolved in water is used, For the following reasons, the amount of dehydrating agent added can be reduced. As a result, the water to be treated containing inorganic sludge can be treated at low cost.
Moreover, since it is not necessary to add a cationic polymer flocculant and an anionic polymer flocculant separately like the conventional method (3), the to-be-processed water containing an inorganic sludge can be processed simply.

  The pH of mud generated in civil engineering / construction work is about 7-12. The specific amphoteric polymer flocculant in the present invention is dissolved in a basic compound aqueous solution having a pH of 9 or more, so that dissociation of the cationic group of the structural unit derived from the monomer (b) is suppressed. When the dehydrating agent is added to the muddy water, the anionic group of the structural unit derived from the monomer (a) in the specific amphoteric polymer flocculant reacts with the inorganic sludge prior to the cationic group, and then gradually. Dissociated cationic groups react with inorganic sludge. Thus, since a specific amphoteric polymer flocculant effectively acts on the water to be treated containing inorganic sludge, a strong and highly hydrophobic aggregate (floc) is formed even with a small amount of addition, Good dehydration treatment is possible, and a dehydrated cake with a low water content can be obtained.

  On the other hand, in the conventional methods (1) and (2) using a dehydrating agent comprising a cationic polymer flocculant, an anionic polymer flocculant and a water-soluble salt, when the dehydrating agent is added to the muddy water, Before the reaction, the cationic polymer flocculant reacts with the anionic polymer flocculant, and the flocculant is not effectively used. Therefore, it is necessary to increase the addition of the dehydrating agent.

  As the amphoteric polymer flocculant, the amide bond (—CONH—) in the monomer (b1) represented by the formula (1) and the monomer (b2) represented by the formula (2) is esterified. An ester-based amphoteric polymer flocculant substituted with a bond (—COO—) is known. However, ester-based amphoteric polymer flocculants are more likely to be hydrolyzed at high pH than the amide-based amphoteric polymer flocculants in the present invention, and are not suitable for the treatment of muddy water.

  Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto. In the examples, “%” indicates mass% unless otherwise specified.

(Measurement of 0.5% salt viscosity)
2.38 g of the powdery polymer flocculant was dissolved in a 4% sodium chloride aqueous solution to prepare 500 g of a 0.5% polymer aqueous solution. Using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd.), the salt viscosity of the polymer aqueous solution after 5 minutes was measured under the conditions of temperature: 25 ° C. and rotation speed: 60 rpm.

(Measurement of 0.5% insoluble content)
The total amount (500 g) of the 0.5% polymer aqueous solution was filtered through a sieve having a diameter of 20 cm and 80 mesh, the moisture on the residue (insoluble matter) on the sieve was wiped off, and the mass was measured.

(Dehydration test)
Bentonite mud water (pH: 7.86, TS (solid content concentration): 23.0%) discharged from a tunnel excavation site by the shield method was prepared.
Calcium hydroxide was added to the muddy water to adjust the pH to 10.9.
In a 500 mL beaker, 300 mL of muddy water (pH: 10.9) was added, then a dehydrating agent was added so as to achieve a predetermined addition rate, and the mixture was stirred with a spatula for 30 seconds to form aggregates (floc). . After measuring the particle size of the formed floc, the floc was dehydrated with a pressure-type dehydrator to obtain a dehydrated cake. The thickness and moisture content of the dehydrated cake were measured. Further, the amount of filtrate discharged from the dehydrator was measured, and the drainage rate was determined from the following formula (3).
Drainage rate (%) = Drainage amount (mL) / (Amount of muddy water (mL) + Amount of dehydrating agent water (mL)) × 100 (3).

(Dehydration conditions)
Dehydration conditions using a pressure-type dehydrator are as follows: 0.05 MPa for 30 seconds, 0.10 MPa for 30 seconds, 0.20 MPa for 30 seconds, 0.30 MPa for 30 seconds, 0.40 MPa for 30 seconds, 0.50 MPa for 30 seconds It was.

(Monomer)
Monomer (a):
Acrylic acid (hereinafter referred to as AA), manufactured by Mitsubishi Chemical Corporation, purity: 50%.
Monomer (b):
N, N-dimethylaminopropylacrylamide (hereinafter referred to as DMAPAA), manufactured by Kojin Co., Ltd., purity: 100%.
Methacryloylaminopropyltrimethylammonium chloride (hereinafter referred to as MAPTAC), manufactured by MRC Unitech, purity: 98%.
Other monomer (c):
Acrylamide (hereinafter referred to as AAM), manufactured by Dianitics, purity: 50%.
N, N-dimethylaminoethyl methacrylate sulfate (hereinafter referred to as DMZ), purity: 70%.
N, N-dimethylaminoethyl acrylate methyl chloride quaternary salt (hereinafter referred to as DME), manufactured by Osaka Organic Chemical Industry Co., Ltd., purity: 80%.

(Photoinitiator)
DAROCUR 1173 (hereinafter referred to as D-1173), manufactured by Ciba.
(Chain transfer agent)
Hypophosphorous acid (hereinafter referred to as HA), manufactured by Kanto Chemical Co., Inc.

[Production Example 1]
38.7 g of DMAPAA, 77.0 g of AA, and 616.0 g of AAM were put into a 2000 mL brown heat-resistant bottle, and distilled water was added so that the total monomer concentration was 35% and the total mass was 1100 g. A monomer aqueous solution was prepared. Furthermore, D-1173 and HA were added so as to be 70 ppm and 50 ppm, respectively, with respect to the total mass of the monomer aqueous solution, and the temperature of the aqueous solution was adjusted to 10 ° C. while blowing nitrogen gas for 30 minutes. Thereafter, the aqueous monomer solution was transferred to a stainless steel reaction vessel, and sprayed with 17 ° C. water from below the vessel, using a chemical lamp, the surface thermometer was 30 W from the upper side of the vessel with an irradiation intensity of 7 W / m ^2. Light was irradiated until the temperature reached ℃. After the surface thermometer reached 30 ° C., light was irradiated for 45 minutes at an irradiation intensity of 0.5 W / m ² . Further, in order to reduce the remaining amount of the monomer, irradiation was performed for 10 minutes at an irradiation intensity of 50 W / m ² . Thereby, a hydrogel polymer was obtained.

  The hydrogel polymer was taken out from the container and crushed using a small meat chopper. This was dried at a temperature of 60 ° C. for 16 hours and then pulverized to obtain a powdered amide-based amphoteric polymer flocculant (AAC-1). The proportion of structural units derived from each monomer in AAC-1 was calculated from the charged amount of each monomer. In addition, 0.5% salt viscosity and 0.5% insoluble content were measured. The results are shown in Table 1.

[Production Example 2]
39.3 g of MAPTAC, 77.0 g of AA and 616.0 g of AAM were put into a 2000 mL brown heat-resistant bottle, and distilled water was added so that the total monomer concentration was 35% and the total mass was 1100 g. A monomer aqueous solution was prepared. Furthermore, D-1173 and HA were added so as to be 70 ppm and 40 ppm, respectively, with respect to the total mass of the monomer aqueous solution. Thereafter, the same operation as in Production Example 1 was performed to obtain an amide-based amphoteric polymer flocculant (AAC-2). The proportion of structural units derived from each monomer in AAC-2 was calculated from the charged amount of each monomer. In addition, 0.5% salt viscosity and 0.5% insoluble content were measured. The results are shown in Table 1.

[Production Examples 3 to 6]
Except having changed the ratio of each monomer, operation similar to manufacture example 1 was performed and the amide system amphoteric polymer flocculent (AAC-3-6) was obtained. The ratio of the structural unit derived from each monomer in AAC-3 to 6 was calculated from the charged amount of each monomer. In addition, 0.5% salt viscosity and 0.5% insoluble content were measured. The results are shown in Table 1.

[Production Example 7]
DMZ 55.0 g, AA 77.0 g and AAM 616.0 g were put into a 2000 mL brown heat-resistant bottle, and distilled water was added so that the total monomer concentration was 35% and the total mass was 1100 g. A monomer aqueous solution was prepared. Furthermore, D-1173 and HA were added so as to be 70 ppm and 45 ppm, respectively, with respect to the total mass of the monomer aqueous solution. Thereafter, the same operation as in Production Example 1 was performed to obtain an ester-based amphoteric polymer flocculant (EAC-1). The ratio of the structural unit derived from each monomer in EAC-1 was calculated from the charged amount of each monomer. In addition, 0.5% salt viscosity and 0.5% insoluble content were measured. The results are shown in Table 1.

[Production Example 8]
48.1 g of DME, 77.0 g of AA, and 616.0 g of AAM were put into a 2000 mL brown heat-resistant bottle, and distilled water was added so that the total monomer concentration was 35% and the total mass was 1100 g. A monomer aqueous solution was prepared. Furthermore, D-1173 and HA were added so as to be 70 ppm and 50 ppm, respectively, with respect to the total mass of the monomer aqueous solution. Thereafter, the same operation as in Production Example 1 was performed to obtain an ester-based amphoteric polymer flocculant (EAC-2). The proportion of structural units derived from each monomer in EAC-2 was calculated from the charged amount of each monomer. In addition, 0.5% salt viscosity and 0.5% insoluble content were measured. The results are shown in Table 1.

[Production Example 9]
176.0 g of AA and 704.0 g of AAM are put into a 2000 mL brown heat-resistant bottle, and distilled water is added so that the total monomer concentration is 40% and the total mass is 1100 g to prepare an aqueous monomer solution. did. Furthermore, D-1173 and HA were added so as to be 70 ppm and 40 ppm, respectively, with respect to the total mass of the monomer aqueous solution. Thereafter, the same operation as in Production Example 1 was performed to obtain an anionic polymer flocculant (A-1). The ratio of the structural unit derived from each monomer in A-1 was calculated from the charged amount of each monomer. In addition, 0.5% salt viscosity and 0.5% insoluble content were measured. The results are shown in Table 1.

[Production Example 10]
110.0 g of DME and 704.0 g of AAM are put into a 2000 mL brown heat-resistant bottle, and distilled water is added so that the total monomer concentration is 40% and the total mass is 1100 g to prepare a monomer aqueous solution. did. Furthermore, D-1173 and HA were added so as to be 70 ppm and 30 ppm, respectively, with respect to the total mass of the monomer aqueous solution. Thereafter, the same operation as in Production Example 1 was performed to obtain a cationic polymer flocculant (C-1). The ratio of the structural unit derived from each monomer in C-1 was calculated from the charged amount of each monomer. In addition, 0.5% salt viscosity and 0.5% insoluble content were measured. The results are shown in Table 1.

[Example 1]
0.59 g of sodium hydroxide was added to 498.0 mL of water to obtain an aqueous alkaline solution having a pH of 12.0. To the alkaline aqueous solution, 1.5 g of an amide-based amphoteric polymer flocculant (AAC-1) was added and dissolved with sufficient stirring to obtain a dehydrating agent.
A dehydration test was performed using the dehydrating agent so that the addition rate of the flocculant was a value shown in Table 2. The results are shown in Table 2.

[Examples 2 to 6]
A dehydrating agent was obtained in the same manner as in Example 1 except that the amide-based amphoteric polymer flocculant (AAC-1) was changed to the amide-based amphoteric polymer flocculant (AAC-2 to 6).
A dehydration test was performed using the dehydrating agent so that the addition rate of the flocculant was a value shown in Table 2. The results are shown in Table 2.

[Comparative Examples 1 and 2]
A dehydrating agent was obtained in the same manner as in Example 1 except that the amide amphoteric polymer flocculant (AAC-1) was changed to an ester amphoteric polymer flocculant (EAC-1).
A dehydration test was performed using the dehydrating agent so that the addition rate of the flocculant was a value shown in Table 2. The results are shown in Table 2.

[Comparative Examples 3 and 4]
A dehydrating agent was obtained in the same manner as in Example 1 except that the amide amphoteric polymer flocculant (AAC-1) was changed to the ester amphoteric polymer flocculant (EAC-2).
A dehydration test was performed using the dehydrating agent so that the addition rate of the flocculant was a value shown in Table 2. The results are shown in Table 2.

[Comparative Example 5]
To 499.5 mL of water, 0.5 g of the anionic polymer flocculant (A-1) was added and dissolved with sufficient stirring to obtain a dehydrating agent (A).
Separately from this, 0.15 g of sulfamic acid was added to 498.35 mL of water to obtain an acid aqueous solution having a pH of 2.0. To the acid aqueous solution, 1.5 g of the cationic polymer flocculant (C-1) was added and dissolved by sufficiently stirring to obtain a dehydrating agent (C).
A dehydration test was performed by adding the dehydrating agent (A) and the dehydrating agent (C) to the muddy water in this order so that the addition rate of each coagulant becomes the value shown in Table 2. The results are shown in Table 2.

  The method for treating water to be treated containing inorganic sludge according to the present invention is useful as a method for dewatering water to be treated in which inorganic sludge such as bentonite mud hardly aggregates.

DESCRIPTION OF SYMBOLS 10 Processing system 12 Mud storage tank 14 Coagulation reaction tank 16 Dehydrator 18 Dehydrating agent tank

Claims (3)

In a method for treating water to be treated containing inorganic sludge, the method includes adding a dehydrating agent to water to be treated containing inorganic sludge, and aggregating the inorganic sludge to obtain treated water containing aggregates.
Furthermore, it has the process of adjusting pH of the to-be-processed water containing the said inorganic sludge to 7-11 beforehand,
The treated water containing the inorganic sludge is muddy water containing a mud adjuster,
A method for treating water to be treated containing inorganic sludge, wherein the dehydrating agent is obtained by dissolving a basic compound and the following amphoteric polymer flocculant in water.
Amphoteric polymer flocculant: a structural unit derived from the monomer (a) having a carboxy group, and a monomer represented by the following formula (1) (b1) or the following formula (2) A polymer having a structural unit derived from the body (b2).

In the formula, R ¹ is a hydrogen atom or a methyl group, R ² is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ³ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. and a, ^{R 4} is an alkyl group or a benzyl group having 1 to 4 carbon atoms, Z ^- is Cl ^- or 1 / _2SO ^{4 2-.}   Furthermore, the processing method of the to-be-processed water containing an inorganic sludge of Claim 1 which has the process of dehydrating the treated water containing the said aggregate. The amphoteric polymer flocculant is 5 to 20 mol% of the structural unit derived from the monomer (a) and 2 of the structural unit derived from the monomer (b1) or the monomer (b2). Water to be treated containing inorganic sludge according to claim 1 or 2 , which is a polymer having -20 mol% and 60-93 mol% of structural units derived from other monomers (c). Processing method.

Images