JP2016163849A - Method for dewatering sludge using water-in-oil emulsion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for dewatering sludge using a polyvinylamine-based water-soluble polymer whose performance is superior to those of conventional polyvinylamine-based water-soluble polymers, polyamidine-based water-soluble polymers and acrylic water-soluble polymers as a flocculation treatment agent.SOLUTION: Addition of a polyvinylamine water-in-oil emulsion having an inherent viscosity at 25°C in an NaCl aqueous solution of 1 mol/L concentration of 4.0 to 10.0 dL/g, a 0.2 mass% aqueous solution viscosity of 10 to 200 mPa s and an amination degree in the range of 30 to 80 mol% to organic sludge enables more efficient dewatering treatment compared with conventional polyvinylamine-based water-soluble polymers, polyamidine-based water-based polymers and acrylic water-based polymers.SELECTED DRAWING: None

Description

The present invention relates to a sludge dewatering method using an aggregating agent, and more particularly to a sludge dewatering method of adding a water-in-oil emulsion of polyvinylamine to organic sludge.

A sewage treatment plant is a method of dewatering by adding an aggregating agent to organic sludge such as primary sludge settled from sewage, surplus sludge settled from runoff from an activated sludge tank, or mixed sludge. It is used. As the flocculating agent, polyacrylamide (PAM) water-soluble polymer flocculants are generally used. Polyvinylamine water-soluble polymers and polyamidine water-soluble polymers have a dehydrated cake water content specifically. It is known that it is important to properly use the PAM-based water-soluble polymer flocculant. This phenomenon is due to the difference between tertiary amino groups and quaternary ammonium salts in PAM water-soluble polymer flocculants and primary or secondary amino groups in polyvinylamine water-soluble polymers and polyamidine water-soluble polymers. It is suggested that it is caused. In particular, it is known that polyamidine-based water-soluble polymers exhibit an excellent effect on so-called hardly dewatering sludge with a low fiber content because of their high cationicity and specific structure. However, polyamidine-based water-soluble polymers are required to have a high addition rate, resulting in high chemical costs and a relatively narrow treatment pH range. In addition, it has been pointed out that the manufacturing is unstable.

On the other hand, the polyvinylamine-based water-soluble polymer is a primary amino group-containing vinyl polymer having the simplest structure, and a method of hydrolyzing a polymer of N-vinylcarboxylic acid amide with an acid or a base, N-vinyl-O A method of hydrolyzing a polymer of -t-butyl carbamate or a method of performing a Hofmann reaction of polyacrylamide in the presence of hypohalous acid and alkali metal hydroxide are known. The method of hydrolyzing the polymer of the N-vinylcarboxylic acid amide monomer with an acid or a base makes it easy to synthesize the monomer as a raw material, and the hydrolysis of the radical polymerization reaction product of N-vinylcarboxylic acid amide. It is useful as an industrial production method because a polymer having a high molecular weight can be obtained relatively easily by decomposition and has high safety.
Therefore, various methods using polyvinylamine as an aggregating agent have been proposed. For example, Patent Document 1 proposes a polymer flocculant composed of a polymer containing 2 to 30 mol% of benzylated vinylamine units. In Patent Document 2, a cationic polymer flocculant having a vinylamine unit and a self-emulsifying antifoaming agent comprising a polyoxyalkylene fatty acid ester, a polyoxyalkylene alkyl ether, a polyoxyalkylene alkenyl ether or a polyoxyalkylene ether ester are added. A sludge dewatering method is disclosed. Patent Document 3 discloses a flocculating agent for a vinylamine water-soluble polymer in a water-in-oil emulsion. In many cases, it is presumed that these polyvinylamine-based water-soluble polymers do not provide satisfactory treatment effects under the present circumstances. This is because the polyvinylamine-based water-soluble polymer has a lower molecular weight than the PAM-based water-soluble polymer flocculant, and the addition rate cannot be increased due to the cost of chemicals. This is because a polyvinylamine-based water-soluble polymer having appropriate physical properties is not applied. Therefore, it is considered that the specific effects of polyvinylamine-based water-soluble polymers are not fully demonstrated, and there is a demand for the development of sludge dewatering formulations using higher-performance polyvinylamine-based water-soluble polymers as coagulation treatment agents. Has been.

JP 7-328323 A JP-A-9-299998 JP 2013-252476 A

An object of the present invention is to provide a method for dewatering sludge using a polyvinylamine-based water-soluble polymer that is superior in performance to conventional polyvinylamine-based water-soluble polymers that exhibit a specific effect as a coagulation treatment agent. It is in.

As a result of intensive studies to solve the above problems, the present invention has been completed based on the knowledge described below. That is, the intrinsic viscosity at 25 ° C. in a 1 mol / L NaCl aqueous solution is 4.0 to 10.0 dL / g, the 0.2 mass% aqueous solution viscosity is 10 to 200 mPa · s, and the amination degree is 30 to 30%. It has been found that by adding a coagulation treatment agent composed of a water-in-oil emulsion of polyvinylamine in the range of 80 mol% to organic sludge, dehydration can be performed more efficiently than conventional polyvinylamine.

The water-in-oil emulsion of polyvinylamine in the present invention can also be used as a sludge dewatering agent, a sludge settling agent, or a wastewater treatment agent as a coagulation treatment agent.

The water-in-oil emulsion of polyvinylamine in the present invention has a specific composition and physical property values compared to the commonly used polyvinylamine water-soluble polymer, and therefore excellent dehydration when using organic sludge as a countermeasure. Demonstrate the processing effect.

The water-in-oil emulsion of polyvinylamine in the present invention can be produced by a known method for producing polyvinylamine. The intrinsic viscosity at 25 ° C. in a 1 mol / L NaCl aqueous solution is 4.0 to 10.0 dL / g, the 0.2 mass% aqueous solution viscosity is 10 to 200 mPa · s, and the amination degree is 30 to 80 mol. %, Any production method may be adopted, but basically there is a method for producing a water-in-oil emulsion of a polymer of N-vinylcarboxylic acid amide by hydrolysis. preferable. In this method, first, N-vinylcarboxylic acid amide monomer is water, an oily substance composed of a water-immiscible hydrocarbon, a surfactant having an amount effective for forming a water-in-oil emulsion and HLB. Are mixed and vigorously stirred to form a water-in-oil emulsion, followed by polymerization. The method of hydrolyzing the polymer of the N-vinylcarboxylic acid amide monomer with an acid or a base makes it easy to synthesize the monomer as a raw material, and the hydrolysis of the radical polymerization reaction product of N-vinylcarboxylic acid amide. It is useful because a polymer having a high molecular weight can be obtained relatively easily by decomposition and has high safety. Methods for producing such a water-in-oil emulsion of polyvinylamine are disclosed in JP-T-10-500714, JP-A-5-117313, JP-A-2012-153747, and the like.

  Among these known production methods, as disclosed in JP2012-153747, a water-in-oil emulsion of an aqueous solution of N-vinylcarboxylic acid amide polymer in which polyoxyalkylene alkyl ether coexists as a surfactant is used. The production method by hydrolysis in the presence of an acid or base is a preferred production method because a product having a high molecular weight can be stably obtained. Hereinafter, polyvinylamine conforming to this method will be described, but a known production method may be used in combination. Any method can be applied as long as the physical properties of the water-in-oil emulsion of polyvinylamine in the present invention are obtained.

Examples of N-vinylcarboxylic acid amide monomers include N-vinylformamide, N-vinylacetamide, N-methyl-N-vinylformamide, N-methyl-N-vinylacetamide, N-vinylformamide Is preferably used.

Examples of oily substances composed of water-immiscible hydrocarbons include paraffins, mineral oils such as kerosene, light oil, and middle oil, or hydrocarbon-based synthesis having characteristics such as boiling point and viscosity in substantially the same range as these. An oil or a mixture thereof may be mentioned. As content, it is 20-50 mass% with respect to the water-in-oil type emulsion whole quantity, Preferably it is 20-35 mass%.

Examples of surfactants having an effective amount and HLB to form a water-in-oil emulsion include nonionic surfactant polyoxyethylene alkyl ethers, polyoxyethylene alcohol ethers, polyoxyethylene alkyl esters System or block and / or graft type polymer surfactants having a molecular weight of 1000 or more. Specifically, surfactants with a molecular weight of less than 1000 having an HLB value of 2-10, preferably 3-7, eg glycerol fatty acid esters such as glycerol mono-, di-, and tri-, oleate, stearate or palmitate, sorbitan Examples thereof include sorbitan fatty acid esters such as mono-, di-, and poly-, oleate, stearate or palmitate, and adducts of these ethylene oxide and / or propylene oxide. As a block and / or graft type polymer surfactant having a molecular weight of 1000 or more, a polyester block-poly (ethylene oxide) block-polyester block copolymer which is a reaction product of 12-hydroxystearic acid and poly (ethylene oxide) is used. Can be illustrated. Of these, two or more surfactants can be used in combination. In particular, it is preferable to use a surfactant having a molecular weight of less than 1000 and a block and / or graft-type polymer surfactant having a molecular weight of 1000 or more, and the addition amount is 0.5 to the total amount of the water-in-oil emulsion. It is 10 mass%, Preferably it is the range of 1-5 mass%.

Polymerization is performed using a radical polymerization initiator. These initiators may be either oil-soluble or water-soluble, and can be polymerized by any of azo, peroxide, and redox systems. Examples of oil-soluble azo initiators are 2,2′-azobisisobutyronitrile, 1,1′-azobiscyclohexanecarbonitrile, 2,2′-azobis-2-methylbutyronitrile, 2'-azobis-2-methylpropionate, 2,2'-azobis- (4-methoxy-2,4-dimethyl) valeronitrile and the like.

Examples of water-soluble azo initiators are 2,2′-azobis (amidinopropane) dichloride, 2,2′-azobis [2- (5-methyl-imidazolin-2-yl) propane] hydrogen dichloride And 2,2′-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride, 4,4′-azobis (4-cyanovaleric acid), and the like. Examples of redox systems include a combination of ammonium peroxodisulfate and sodium sulfite, sodium hydrogen sulfite, trimethylamine, tetramethylethylenediamine and the like. Examples of peroxides include ammonium or potassium peroxodisulfate, hydrogen peroxide, benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, succinic peroxide, t-butylperoxy-2-ethylhexanoate, etc. Can be mentioned.

The polymerization temperature is appropriately determined depending on the polymerization initiator to be used, and is usually in the range of 0 to 100 ° C, and particularly preferably in the range of 10 to 60 ° C.

In addition, a compound having chain transfer property can be used in combination for adjusting the molecular weight, and for example, 2-mercaptoethanol, 2-propanol, sodium bisulfite, sodium methallylsulfonate, sodium hypophosphite, etc. can be used. .

The concentration of N-vinylcarboxylic amide is appropriately set, but is usually in the range of 10 to 50% by mass, particularly preferably in the range of 15 to 40% by mass, based on the total amount of the water-in-oil emulsion.

Next, the hydrolysis of the N-vinylcarboxylic acid amide polymer in the water-in-oil emulsion will be described. The stable water-in-oil emulsion of polyvinylamine of the present invention can hydrolyze the water-in-oil emulsion of the N-vinylcarboxylic acid amide polymer with an acid or a base. It is possible to select appropriately according to the purpose, and when it is necessary to use in the presence of an acid, it is preferable to hydrolyze with an acid. In the hydrolysis with an acid, formic acid is generated as a by-product and corrodes the production tank or the storage tank. Therefore, hydrolysis with a base is preferable.

The acid suitable for the hydrolysis is not particularly limited as long as the pH can be adjusted to a range of 0 to 5 during the hydrolysis, and includes inorganic acids such as hydrohalic acid, sulfuric acid, nitric acid and phosphoric acid, and one carbon atom. Examples thereof include organic acids such as mono- and dicarboxylic acids, sulfonic acids, benzenesulfonic acids, and toluenesulfonic acids in the range of ˜5, and it is particularly preferable to use hydrohalic acid and hydrogen halide gas, and use hydrohalic acid. Most preferred. The addition amount is preferably 0.05 to 2, more preferably 0.4 to 1.2 equivalents relative to the formyl group of the polymer.

As a suitable base for the hydrolysis, there is no limitation as long as the pH can be set in the range of 8 to 14 in the hydrolysis, and metal hydroxides of group 1a and 2a of the periodic table, ammonia and ammonia The first and second group 2a metal hydroxides and ammonia are preferably used, and an aqueous solution of sodium hydroxide, potassium hydroxide, and ammonia is most preferably used. The addition amount is preferably 0.05 to 2, more preferably 0.4 to 1.2 equivalents relative to the formyl group of the polymer.

The hydrolyzed water-in-oil emulsion of polyvinylamine can be neutralized with the acid or base, and the pH is preferably adjusted in the range of 6.0 to 14.0.

The hydrolysis must be carried out in the presence of polyoxyethylene alkyl ether in the range of HLB 8.0-14.0. Examples of such polyoxyethylene alkyl ethers include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, and polyoxyethylene oleyl ether. These polyoxyethylene alkyl ethers can be added at the time of polymerization of N-vinylcarboxylic acid amide, or can be added before hydrolysis after polymerization, but are added after polymerization and before hydrolysis step. The method is preferred.

In order to prevent an unintended crosslinking reaction, the hydrolysis reaction can be performed in the presence of hydroxylamine hydrochloride. This hydroxylamine hydrochloride is preferably added after polymerization and before hydrolysis.

The temperature at which the hydrolysis is performed can be appropriately selected depending on the hydrolysis rate and the time for the hydrolysis, but is usually 40 to 100 ° C., preferably 60 to 90 ° C.

The intrinsic viscosity of polyvinylamine thus obtained in a 1 mol / L NaCl aqueous solution at 25 ° C. is 4.0 to 10.0 dL / in order to exhibit the effect as an aggregating agent of the present invention. It must be in the range of g. In addition, an intrinsic viscosity is the value which measured the polyvinylamine hydrochloride neutralized with hydrochloric acid until it became pH7. If the intrinsic viscosity is 4.0 dL / g or less, the cohesive force is lowered, and if it is higher than 10.0 dL / g, the floc becomes excessively large, and excessive moisture is taken in, so that the water content is lowered. If it is greater than 8.0 dL / g, the viscosity of the aqueous solution becomes high, and the viscosity of the 0.2 mass% aqueous solution is likely to exceed 200 mPa · s. Therefore, the viscosity is preferably 4.0 to 8.0 dL / g, more preferably 4. The range is 0 to 6.0 dL / g.

After the hydrolysis, it is preferable to add a hydrophilic surfactant to make the emulsion particles covered with the oil film easy to adjust to water and to make the water-soluble polymer therein easily dissolve. Examples of hydrophilic surfactants are cationic surfactants and HLB 9-15 nonionic surfactants, and examples include polyoxyethylene polyoxypropylene alkyl ethers and polyoxyethylene alcohol ethers.

The polyvinylamine in the present invention is a water-in-oil emulsion produced by an emulsion polymerization method and has a higher molecular weight than a polyvinylamine water-soluble polymer produced by aqueous solution polymerization or reverse phase suspension polymerization. It is considered that entanglement is caused by the contraction of, and the electric charge tends to be included. For this reason, the water contained in the water-in-oil emulsion of polyvinylamine in the present invention is added to the sludge, and the electric charge contained by the stirring gradually appears on the outside of the polymer to neutralize the suspended matter in the sludge and the charge. As a result of repeating the action and re-aggregation, it is considered that a dense and strong floc is formed and the moisture content of the cake is lowered. The relationship between the molecular weight and the charge inclusion degree is not necessarily high when the molecular weight is high. This is because it is influenced by the polymerization conditions and hydrolysis conditions of the N-vinylcarboxylic acid amide polymer, the degree of amination of polyvinylamine, and the like. In addition, if the charge inclusion rate is high, it cannot be said that the treatment effect is high, so that the intrinsic viscosity of the water-in-oil emulsion of polyvinylamine in the present invention is in the range of 4.0 to 10.0 dL / g. It is a condition.

Next, the use of the water-in-oil emulsion of polyvinylamine in the present invention will be specifically described. The sludge to which the water-in-oil emulsion of polyvinylamine in the present invention can be applied is the primary sludge settled from the sewage, the surplus sludge settled from the effluent from the activated sludge tank or these Organic sludge such as mixture (usually referred to as “mixed raw sludge”), digested sludge and the like. It is particularly effective for sludge with a low organic matter (VSS) and sludge with a low fiber content (crude suspended matter) and is particularly effective for mixed raw sludge and digested sludge. When the water-in-oil emulsion of polyvinylamine in the present invention is added to these organic sludges, a strong floc is formed. When this floc is processed by a pressure dehydrating device such as a belt press, screw press, filter press, or a dehydrating device such as a centrifugal separator or a vacuum filter, dehydration can be performed with a remarkable effect. A dehydrated cake is obtained. This is presumably because the degree of amination, intrinsic viscosity, and aqueous solution viscosity of the water-in-oil emulsion of polyvinylamine in the present invention has an optimal composition and physical properties with respect to organic sludge. The water-in-oil emulsion of polyvinylamine used in the present invention is a cationic polymer having a primary amino group and has a strong adsorptivity to suspended particles in sludge. Therefore, it forms a strong and not too big floc. As a result, the moisture content of the dewatered cake is reduced and the sludge treatment efficiency is very high. In addition, the molecular weight is higher than that of the conventional polyvinylamine-based water-soluble polymer. In the present invention, the intrinsic viscosity is adopted as an index of the molecular weight, but the intrinsic viscosity at 25 ° C. in a 1 mol / L NaCl aqueous solution is adopted. It is the range of 4.0-10.0 dL / g. This is because if less than 4.0 dL / g, the cohesive force is insufficient, and if it exceeds 10.0 dL / g, it is estimated that the solution viscosity becomes too high and the dispersibility is lowered. 8.0 dL / g or less is preferable. This is in the range of 1 million to 5 million when expressed in terms of weight average molecular weight, preferably less than 4 million.
The water-in-oil emulsion of polyvinylamine in the present invention is hydrolyzed with an acid or alkali of N-vinylcarboxylic acid amide, and cationized by converting the acid amide group to an amino group. It is preferable for the sludge dehydrating agent to leave the acid amide group rather than completely hydrolyze. This is considered to be due to the balance between the acid amide group which is a nonionic group and the primary amino group which is a hydrophilic group. Accordingly, the degree of amination is preferably 30 to 80 mol%, more preferably 40 to 80 mol%, still more preferably 50 to 80 mol%.

  The aqueous solution viscosity of the water-in-oil emulsion of polyvinylamine in the present invention is influenced by the degree of amination, molecular weight, and polymerization conditions, but it is much higher than that of acrylic water-soluble polymers generally used as an aggregating agent. Low, for example, a 0.2% by weight aqueous solution viscosity measured at 25 ° C. with a rotational viscometer is in the range of 10 to 200 mPa · s with respect to the acrylic water-soluble polymer of about 300 to 1000 mPa · s, Preferably it is 10-150 mPa * s, More preferably, it is 10-100 mPa * s. Because of its low viscosity, when added to target sludge and wastewater, it has good dispersion and excellent adsorptivity with suspended particles, and the synergistic effect of the degree of amination and intrinsic viscosity is in the optimal range. Will be promoted. However, if it is less than 10 mPa · s, the aggregation effect is lowered, which is not preferable.

  The salt solution viscosity measured with a rotational viscometer at 25 ° C. when the polymer concentration is completely dissolved in 4% by mass saline to 0.5% by mass is in the range of 10 mPa · s to 50 mPa · s. become. The viscosity in a 4% by mass aqueous sodium chloride solution having a polymer concentration of 0.5% by mass is a value measured with a No. 2 rotor and 30 rpm in a B-type viscometer.

The water-in-oil emulsion of polyvinylamine in the present invention is dissolved and diluted with water to an arbitrary concentration and added to sludge. However, in order to maximize the effect of low viscosity, the dissolution concentration is 0.05 to 0.00. 3 mass% is preferable. Although the addition rate with respect to sludge changes with sludge seed | species and a dehydration model, it is 0.005-2.0 mass% normally with respect to sludge solid content. Moreover, you may use together with inorganic type coagulants, such as ferric chloride, ferric sulfate, PAC, and a sulfuric acid band. The type of dehydrator to be used can correspond to a belt press, a centrifugal dehydrator, a screw press, a multi-disc dehydrator, a rotary press, a filter press and the like.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not restrict | limited to a following example, unless the summary is exceeded.

  A water-in-oil emulsion sample group X of polyvinylamine in the present invention was prepared based on the method disclosed in JP2012-153747A. The physical property value is a hydrochloride unit of polyvinylamine neutralized with hydrochloric acid until pH 7 is reached. Similarly, a sample group Y outside the range of the water-in-oil emulsion of polyvinylamine in the present invention was prepared. Table 1 shows the physical properties of each sample. In addition, a water-soluble polymer sample group Z was prepared as a commercially available aggregating agent. Table 2 shows the physical properties of each sample.

(Table 1)
Degree of amination: mole fraction (mol%) relative to the charged N-vinylformamide.
Intrinsic viscosity: Intrinsic viscosity at 25 ° C. in a 1 mol / L NaCl aqueous solution.
0.2 mass% aqueous solution viscosity; 0.2 mass% polymer aqueous solution was measured with a B-type viscometer (25 ° C.).

(Table 2)
0.5 mass% salt aqueous solution viscosity: 4 mass% sodium chloride was added to a 0.5 mass% polymer aqueous solution, and after complete dissolution, measured with a B-type viscometer (25 ° C.)
0.2 mass% aqueous solution viscosity; 0.2 mass% polymer aqueous solution was measured with a B-type viscometer (25 ° C.).
Sample-A: polyamidine-based water-soluble polymer, cation equivalent 5.2 meq / g (pH 7).
Sample-E: polyvinylamine-based water-soluble polymer, cation equivalent of 4.3 meq / g (pH 7).

Example 1
A sludge dewatering test was carried out on sewage mixed raw sludge (pH 5.7, SS content 14250 mg / L, organic matter amount 73.7% by mass / SS, crude suspended matter amount 955 mg / L, electrical conductivity 435 mS / m). 200 mL of sludge was collected in a poly beaker, 0.2% by mass of the sample group X in Table 1 was added at 125 ppm or 150 ppm for the sludge SS, and the beaker was transferred and stirred 20 times, and then a nylon filter cloth (# 202), and the filtrate amount and floc diameter after 60 seconds were measured. After the measurement, the sludge filtered for 60 seconds was dehydrated at a press pressure of 3 kg / cm ² for 60 seconds, and the moisture content of the cake (dried at 105 ° C. for 20 hours) was measured. The results are shown in Table 3.

(Comparative Example 1) A similar test was performed on the same sludge as in Example 1, using Sample Group Y in Table 1 and Sample Group Z in Table 2. These results are shown in Table 3.

(Table 3)

Compared with addition of water-in-oil emulsion of polyvinylamine in the present invention, composition outside of range, addition of water-in-oil emulsion of polyvinylamine having physical properties, or addition of polyamidine water-soluble polymer or acrylic water-soluble polymer It can be seen that the water content reduction effect is excellent. The commercially available polyvinylamine-based water-soluble polymer did not form flocs due to poor aggregation. This is probably because the molecular weight is insufficient.

(Example 2)
A sludge dewatering test was carried out on sewage digested sludge (pH 7.7, SS content 11000 mg / L, organic matter amount 70.5% by mass / SS, crude suspended matter amount 594 mg / L, electrical conductivity 732 mS / m). 200 mL of sludge was collected in a poly beaker, and 0.2 ppm by mass of the sample group X in Table 1 was added to each sludge SS content of 200 ppm, transferred to the beaker and stirred 20 times, and then a nylon filter cloth (# 202) The amount of filtrate and the floc diameter after 60 seconds were measured. After the measurement, the sludge filtered for 60 seconds was dehydrated at a press pressure of 3 kg / cm ² for 60 seconds, and the moisture content of the cake (dried at 105 ° C. for 20 hours) was measured. The results are shown in Table 4.

(Comparative Example 2) A similar test was performed on the same sludge as in Example 2, using the sample group Y in Table 1 and the sample group Z in Table 2. These results are shown in Table 4.

(Table 4)

Addition of water-in-oil emulsion of polyvinylamine in the present invention, composition out of range, reduced cohesiveness and water content compared to addition of water-in-oil emulsion of polyvinylamine having physical properties or addition of acrylic water-soluble polymer It turns out that an effect is excellent. The polyamidine-based water-soluble polymer did not form flocs due to poor aggregation.

(Example 3)
A sludge dewatering test was carried out on sewage mixed raw sludge (pH 5.3, SS content 18500 mg / L, organic matter amount 89.2% by mass / SS, crude suspended matter amount 6802 mg / L, electric conductivity 200 mS / m). 200 mL of sludge was collected in a poly beaker, 0.2 mass% solution of sample group X in Table 1 was added to each sludge SS content of 100 ppm, transferred to the beaker and stirred 20 times, and then a nylon filter cloth (# 202) The amount of filtrate and the floc diameter after 60 seconds were measured. After the measurement, the sludge filtered for 60 seconds was dehydrated at a press pressure of 3 kg / cm ² for 60 seconds, and the moisture content of the cake (dried at 105 ° C. for 20 hours) was measured. The results are shown in Table 5.

(Comparative Example 3) A similar test was performed on the same sludge as in Example 3, using the sample group Y in Table 1 and the sample group Z in Table 2. These results are shown in Table 5.

(Table 5)

When adding a water-in-oil emulsion of polyvinylamine in the present invention, the composition is out of range, and the water content reduction effect is superior compared to when adding a water-in-oil emulsion of polyvinylamine having physical properties or when adding a polyamidine-based water-soluble polymer. I understand that.

Example 4
A sludge dewatering test was carried out on sewage mixed raw sludge (pH 5.3, SS content 22250 mg / L, organic matter amount 83.1% by mass / SS, coarse suspended matter amount 3066 mg / L, electrical conductivity 453 mS / m). 200 mL of sludge was collected in a poly beaker, 0.2 mass% dissolved solution of sample group X in Table 1 was added to each sludge SS content of 250 ppm, transferred to the beaker and stirred 20 times, and then a nylon filter cloth (# 202) The amount of filtrate and the floc diameter after 60 seconds were measured. After the measurement, the sludge filtered for 60 seconds was dehydrated at a press pressure of 3 kg / cm ² for 60 seconds, and the moisture content of the cake (dried at 105 ° C. for 20 hours) was measured. The results are shown in Table 6.

(Comparative Example 4) A similar test was performed on the same sludge as in Example 4 using the sample group Y in Table 1 and the sample group Z in Table 2. These results are shown in Table 6.

(Table 6)

It can be seen that when the water-in-oil emulsion of polyvinylamine in the present invention is added, the water content reduction effect is superior compared to when the acrylic water-soluble polymer is added. The sludge is a sludge in which a polyamidine-based water-soluble polymer is effective, but the water-in-oil emulsion of polyvinylamine in the present invention exhibits a drainage effect and water content reduction effect equivalent to or better than those of a polyamidine-based water-soluble polymer. It was.

(Example 5)
A sludge dewatering test was carried out on biomass digested sludge (pH 7.7, SS content 32750 mg / L, organic matter amount 60.3% by mass / SS, crude suspended matter amount 2485 mg / L, electrical conductivity 2230 mS / m). 200 mL of sludge was collected in a poly beaker, 0.2% by mass solution of sample group X in Table 1 was added to the sludge SS content of 650 ppm or 750 ppm, respectively, the beaker was transferred and stirred 20 times, and then a nylon filter cloth (# 202), and the filtrate amount and floc diameter after 60 seconds were measured. After the measurement, the sludge filtered for 60 seconds was dehydrated at a press pressure of 3 kg / cm ² for 60 seconds, and the moisture content of the cake (dried at 105 ° C. for 20 hours) was measured. The results are shown in Table 7.

(Comparative Example 5) A similar test was performed on the same sludge as in Example 5, using the sample group Y in Table 1 and the sample group Z in Table 2. These results are shown in Table 7.

(Table 7)

When adding a water-in-oil emulsion of polyvinylamine in the present invention, the composition is out of range, and the water content reduction effect is superior compared to when adding water-in-oil emulsion of polyvinylamine having physical properties or when adding an acrylic water-soluble polymer. I understand that. In addition, it showed a drainage effect and water content reduction effect equivalent to or better than those of polyamidine water-soluble polymers.

(Example 6)
A sludge dewatering test was conducted on sewage surplus sludge (pH 6.1, SS content 12500 mg / L, organic matter amount 86.0% by mass / SS, coarse suspended matter amount 409 mg / L, electrical conductivity 78 mS / m). 200 mL of sludge was collected in a poly beaker, 0.2 mass% solution of sample group X in Table 1 above was added to the sludge SS content 140 ppm, and after stirring for 60 seconds at a stirring rotation speed of 500 rpm in a CST measuring device, a nylon filter cloth (# 202), and the filtrate amount and floc diameter after 60 seconds were measured. After the measurement, the sludge filtered for 60 seconds was dehydrated at a press pressure of 4 kg / cm ² for 60 seconds, and the moisture content of the cake (dried at 105 ° C. for 20 hours) was measured. The results are shown in Table 8.

(Comparative Example 6) A similar test was performed on the same sludge as in Example 6 using the sample group Z in Table 2. These results are shown in Table 8.

(Table 8)

When the water-in-oil emulsion of polyvinylamine in the present invention was added, a better drainage effect and a water content reduction effect were shown than when an acrylic water-soluble polymer or a polyamidine water-soluble polymer was added.

Claims (3)

The intrinsic viscosity at 25 ° C. in a 1 mol / L NaCl aqueous solution is 4.0 to 10.0 dL / g, the 0.2 mass% aqueous solution viscosity is 10 to 200 mPa · s, and the amination degree is 30 to 80 mol. %, A water-in-oil emulsion of polyvinylamine is added to organic sludge, mixed and agglomerated, and then dehydrated by a dehydrator. The sludge dewatering method according to claim 1, wherein the water-in-oil emulsion of polyvinylamine has a degree of amination in the range of 40 to 80 mol%. The method for dewatering sludge according to claim 1 or 2, wherein the water-in-oil emulsion of polyvinylamine has a 0.2 mass% aqueous solution viscosity of 10 to 100 mPa · s.