JP2019141789A - Organic sludge dewatering method - Google Patents

Abstract

To provide an efficient method for dewatering organic sludge in which organic sludge is treated by combining a polymer flocculant and an organic coagulant.SOLUTION: When SLV is a viscosity of 4 mass% sodium chloride solution with a polymer concentration of 0.5 mass% at 25°C of a polymer flocculant and an organic coagulant, a polymer flocculant as the first liquid is added to organic sludge, and after mixing and stirring, an organic coagulant having SLV lower than the SLV of the polymer flocculant is added and mixed, whereby efficient dehydration treatment can be performed.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a sludge dewatering method using a polymer flocculant when treating various sludges, and more particularly to an organic sludge dewatering method using a polymer flocculant and an organic coagulant in combination.

Addition of coagulation treatment agent to organic sludge such as primary sludge settled from sewage, surplus sludge settled from effluent from activated sludge tank or mixed raw sludge, digested sludge obtained by anaerobic digestion of these sludge The dewatering method is used in sewage treatment plants. As an aggregating agent, polyacrylamide (PAM) water-soluble polymer aggregating agents are generally used. However, the recent dehydrated sludge is often ineffective with PAM polymer flocculants alone, and various dewatering formulations have been proposed. First, there is a prescription in which a PAM polymer flocculant is used in combination after adding an inorganic flocculant. This is an action mechanism in which the inorganic flocculant performs charge neutralization on the sludge particles, and the fine flocs generated thereby are crosslinked by the polymer flocculant to form coarse flocs. When using amphoteric PAM among PAM polymer flocculants, the neutralization of the anionically charged organic substances is performed by adding inorganic flocculants, and the carboxyl groups present in the sludge particles are electrically neutralized. It works to make it hydrophobic and to release the water held inside. Next, by adding amphoteric PAM, anionic groups in amphoteric PAM react with excess metal ions remaining in the sludge, and cationic groups react with unreacted carboxyl groups in the sludge to neutralize the charge, An action mechanism of coarsening the floc to facilitate dehydration is conceivable. A prescription for further improving the dehydration efficiency has been proposed with respect to the prescription using this inorganic flocculant.
For example, Patent Document 1 discloses a method of dehydrating sludge after adding and mixing a polymeric cationic polymer flocculant and an inorganic flocculant in this order. Patent Document 2 discloses a sludge dewatering method in which after adding a polymer flocculant to organic sludge, the floc floc is concentrated and an inorganic flocculant is added.
Furthermore, Patent Document 3 discloses a method for dewatering sludge in which an amphoteric polymer flocculant is added to and stirred in sludge, and then an inorganic flocculant is added.
However, when an inorganic flocculant is used as described above, there is a problem that the amount of generated sludge becomes large and the cost for treating the sludge increases. In addition, there is a concern about the release of aluminum compounds and the like contained in the sludge to the environment.
In addition, it is reported that ferric sulfate in combination is effective among inorganic flocculants, but if an inorganic flocculant is added after the polymer flocculant, iron ions migrate to the treated water rather than in the sludge. Yes.
Therefore, a prescription using an organic coagulant instead of an inorganic coagulant has been proposed. For example, Patent Document 4 discloses a sludge dewatering method in which a condensed polyamine cationic polymer flocculant is added to organic sludge and then an amphoteric polymer flocculant is added or mixed, or these mixed flocculants are added. ing. However, for organic sludge, the organic coagulant often does not provide a large dehydrating effect as compared with the inorganic flocculant, and further improvement of the dehydration prescription is desired.

JP 2002-166300 A JP 2012-45441 A JP 2000-15300 A JP 2000-225400 A

An object of the present invention is to provide an efficient method for dewatering organic sludge in which organic sludge is treated by combining a polymer flocculant and an organic coagulant.

As a result of intensive studies to solve the above problems, the present inventor has reached the invention described below. That is, the viscosity measured at 25 ° C. when the polymer concentration is dissolved in 4% by weight saline solution of the polymer flocculant and organic coagulant with respect to the organic sludge is 25%. Then, a polymer flocculant is added as the first liquid, and after mixing and stirring, an organic coagulant having an SLV lower than the SLV of the polymer flocculant is added and mixed.

By applying the polymer flocculant and the organic flocculant in the present invention, the dehydration efficiency can be improved as compared with the inorganic flocculant combination prescription. As a result, the amount of sludge and the associated processing costs are suppressed. The risk of releasing substances harmful to the environmental system in the inorganic flocculant component is reduced.

In the present invention, a sludge dewatering method is performed by adding a polymer flocculant and an organic coagulant to organic sludge. In general, the function of the organic coagulant has an action of neutralizing and coagulating the surface charge of suspended particles that are negatively charged and dispersed. A polymer having a high cation density (cation equivalent value) and a low molecular weight is used as the organic coagulant. On the other hand, the polymer flocculant has an action of agglomerating fine particles by a cross-linking adsorption action on the suspended particles to form coarse flocs, and therefore has a higher molecular weight than the organic flocculant. Also in the present invention, those having these functions alone are used.

In the present invention, a polymer flocculant is added to the first liquid with respect to the organic sludge.
As a polymer flocculant to be added to the first liquid, 10 to 100 mol% of a cationic monomer represented by the following general formula (1), an anionic monomer 0 to 0 represented by the following general formula (2) A polymer flocculant composed of a polymer having 30 mol% and a nonionic monomer of 0 to 90 mol% as a structural unit can be used.
General formula (1)
R ₁ is hydrogen or a methyl group, R ₂ and R ₃ are alkyl or hydroxyalkyl groups having 1 to 3 carbon atoms, R ₄ is an alkyl or alkoxyl group having 1 to 3 carbon atoms, an alkyl group or aryl group having 7 to 20 carbon atoms, A represents oxygen or NH, B represents an alkylene group having 2 to 4 carbon atoms, and X ₁ ⁻ represents an anion.
General formula (2)
R ₅ is hydrogen, methyl group or carboxymethyl group, Q is SO ₃ ⁻ , C ₆ H ₄ SO ₃ ⁻ , CONHC (CH ₃ ) ₂ CH ₂ SO ₃ ⁻ , C ₆ H ₄ COO ⁻ or COO ⁻ , R ₆ represent respectively + _Y ^2, _{Y 1} or _{Y 2} is hydrogen or a cation and - is hydrogen or ^COO.

The cationic monomer represented by the general formula (1) is a quaternized product of a lower alkyl group halide such as methyl chloride or ethyl chloride of dimethylaminoethyl (meth) acrylate or dimethylaminopropylacrylamide. For example, (meth) acryloyloxyethyltrimethylammonium chloride, (meth) acryloyloxyethyldimethylbenzylammonium chloride, (meth) acryloylaminopropyltrimethylammonium chloride, (meth) acryloylaminopropyldimethylbenzylammonium chloride, (meth) acryloyloxy- 2-hydroxypropyltrimethylammonium chloride and the like. These cationic monomers are 10 to 100 mol%, but 30 to 100 mol% is preferable in order to exhibit a more cohesive treatment effect.
Examples of the anionic monomer represented by the general formula (2) include alkali metal salts or ammonium salts such as (meth) acrylic acid or a sodium salt thereof, maleic acid or an alkali metal salt thereof, and acrylamide-2-methyl. Examples include acrylamide alkane sulfonic acid such as propane sulfonic acid or alkali metal salt or ammonium salt thereof. The polymer flocculant has a weight average molecular weight of preferably 1 million to 10 million, more preferably 2 million to 8 million.

  An amidine polymer flocculant can be used as the polymer flocculant added to the first liquid. As the amidine-based polymer flocculant, known ones can be used, and examples thereof include those produced by the method disclosed in JP-A-5-192513. The weight average molecular weight is preferably 1 million to 5 million, and more preferably 2 million to 5 million.

  The polymer flocculant in the present invention is a 4% by weight saline aqueous solution viscosity (SLV; 0.5% by weight) measured at 25 ° C. at 25 ° C. when completely dissolved so that the polymer concentration becomes 0.5% by weight. % Salt aqueous solution viscosity) is in the range of 5 mPa · s to 100 mPa · s, preferably 5 mPa · s to 80 mPa · s. This 0.5 mass% salt aqueous solution viscosity is a value measured with a No. 1 rotor and 60 rpm in a B-type viscometer.

In the present invention, an organic coagulant is added as the second liquid. As the organic coagulant added to the second liquid, those commonly used can be used, for example, dimethylaminoethyl (meth) acrylate polymer, diallylamine polymer, condensed amine polymer. , Ethyleneimine polymer, vinylamine polymer, dicyandiamide polymer and the like.

Examples of tertiary amino group-containing cationic monomers among the cationic monomers used as the dimethylaminoethyl (meth) acrylate polymer are dimethylaminoethyl (meth) acrylate and diethylaminoethyl. Examples include (meth) acrylate, dimethylaminopropyl (meth) acrylamide, diethylaminopropyl (meth) acrylamide, and salts thereof. Examples of cationic monomers containing a quaternary ammonium base include (meth) acryloyloxyethyltrimethylammonium. Chloride, (meth) acryloyloxyethyldimethylbenzylammonium chloride, (meth) acryloylaminopropyltrimethylammonium chloride, (meth) acryloylaminopropyldimethylbenzylammonium chloride De, and (meth) acryloyloxy 2-hydroxypropyl trimethylammonium chloride and the like. Polymers of these cationic monomers alone, polymers of two or more cationic monomers, and copolymers of cationic monomers and nonionic monomers may be used. Nonionic monomers include (meth) acrylamide, N, N-dimethylacrylamide, vinyl acetate, acrylonitrile, methyl acrylate, 2-hydroxyethyl (meth) acrylate, diacetone acrylamide, N-vinyl pyrrolidone, N- Examples include vinylformamide, N-vinylacetamide, acryloylmorpholine, and the like. Among these, a copolymer of one or more of them and a cationic monomer can be used.
Further, these dimethylaminoethyl (meth) acrylate polymers may use an anionic monomer as long as the effect of the cationic structural unit is not inhibited. Examples of the anionic monomer include (meth) acrylic acid, itaconic acid, 2-acrylamido-2-methylsulfonic acid, maleic acid, and salts thereof. The weight average molecular weight of these dimethylaminoethyl (meth) acrylate polymers is preferably in the range of 10,000 to 2,000,000.
The dimethylaminoethyl (meth) acrylate polymer may have the same composition as that of the polymer flocculant, but it is essential that the SLV as an index of molecular weight is lower than the SLV of the polymer flocculant.

Examples of the monomer used as the diallylamine polymer include allylamine, diallylmethylamine and salts thereof, diallyldimethylammonium chloride and the like. One or more selected from these monomers, cationic monomers, nonionic monomers or anionic monomers used in the production of dimethylaminoethyl (meth) acrylate polymers An arbitrarily copolymerized product can also be applied. The weight average molecular weight is preferably in the range of 10,000 to 3,000,000, more preferably 10,000 to 2,000,000.

Examples of the condensed amine polymer include monomethylamine, dimethylamine, monoethylamine, diethylamine, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine and the like, and epichlorohydrin condensates, or the above Examples include those obtained by further condensing an aliphatic amine / epichlorohydrin condensate with ethylenediamine, diethylenetriamine, triethylenetetramine or hexamethylenediamine. The weight average molecular weight is preferably in the range of 1,000 to 100,000.

  Examples of the ethyleneimine polymer include polyethyleneimine or polyethyleneimine metamorphosis. The weight average molecular weight is preferably in the range of 10,000 to 2,000,000.

  Examples of the vinylamine polymer include polyvinylamine and vinylamine units made of a polymer acid or alkali-modified product containing N-vinylcarboxylic acid amide, N-vinylformamide, N-vinylacetamide and the like as essential monomers, and the dimethylaminoethyl ( Examples thereof include a copolymer with one or more selected from a cationic monomer, an anionic monomer, and a nonionic monomer used in producing a (meth) acrylate polymer. The weight average molecular weight is preferably in the range of 10,000 to 2,000,000.

Examples of the dicyandiamide polymer include water-soluble dicyandiamide / formaldehyde condensate or dicyandiamide / formaldehyde / ammonium chloride condensate. Basically, it is a product obtained by adding formaldehyde to dicyandiamide and condensing it in the presence of an acid or its ammonium salt. The weight average molecular weight is preferably in the range of 10,000 to 500,000.

  The cation equivalent value of these organic coagulants at pH 7 is preferably 3.0 meq / g or more. 3.0-22.0 meq / g is a preferable range. The viscosity of the 4% by weight saline solution (SLV) measured with a rotational viscometer at 25 ° C. when the organic coagulant is completely dissolved so that the polymer concentration is 0.5% by weight is preferably 1 to 10 mPa · s. It is a range. The 0.2 mass% aqueous solution viscosity (AQV) measured at 25 ° C. when completely dissolved in water so that the polymer concentration is 0.2 mass% is preferably in the range of 1 to 30 mPa · s. The 0.2 mass% aqueous solution viscosity (AQV) is a value measured with a No. 2 rotor and 30 rpm in a B-type viscometer. A B8M manufactured by Tokyo Keiki Co., Ltd. is used as the B type viscometer. These organic coagulants can be used in combination of two or more.

The product form of the polymer flocculant and organic coagulant in the present invention is not particularly limited, and can be produced by a known method. For example, after polymerization by aqueous solution polymerization, water-in-oil emulsion polymerization, water-in-oil dispersion polymerization, salt-in-water dispersion polymerization, etc., it can be converted into any product form such as aqueous solution, salt-in-water dispersion, water-in-oil emulsion or powder. can do.

In the present invention, a crosslinkable monomer may be used as a structural modifier during or after polymerization when producing the polymer flocculant and organic coagulant. When used, the crosslinkable monomer is present in the range of 0.00005 to 0.050 mass% with respect to the total amount of monomers. Although it varies depending on the monomer composition and polymerization conditions, if it exceeds 0.050 mass%, crosslinking proceeds excessively and becomes insoluble in water, which is not preferable for use in the present invention. Examples of the crosslinkable monomer include N, N′-methylenebis (meth) acrylamide, triallylamine, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, Methacrylic acid-1,3-butylene glycol, polyethylene glycol di (meth) acrylate, N-vinyl (meth) acrylamide, N-methylallylacrylamide, glycidyl acrylate, polyethylene glycol diglycidyl ether, acrolein, glyoxal, vinyltrimethoxy Silane and the like can be mentioned, and N, N′-methylenebis (meth) acrylamide is preferably applied.

The organic sludge to which the sludge dewatering method of the present invention is applied is a sludge having a high organic content ratio that is more difficult to dewater. Specifically, the sludge has an organic substance amount (VSS, loss on ignition in suspended matter, mass% vs. SS) of 45 mass% or more as an index of organic substances. Especially, it is more effective for sludge having a high M-alkalinity and anion content. M-alkalinity is more effective in the range of 500 to 10,000 mg / L, and the amount of anion is more effective in the range of 4.0 to 15.0 meq / L, so application to these sludges is preferable. Various measured values are based on measurements based on a conventional method (sewage test method).

  After adding the polymer flocculant in the present invention, the sludge dewatering method of adding the organic coagulant is to form flocs by the coagulation action due to cross-linking adsorption with particles in the sludge with the first liquid polymer flocculant, It is presumed that by adding an organic coagulant having a high cation amount and a molecular weight within a certain range, the formed flocs are joined by an action mainly composed of coagulation, thereby forming a tighter and stronger floc. The Therefore, it is considered that the dehydration efficiency is increased as compared with the polymer flocculant single formulation and the inorganic flocculant combined formulation.

  In the sludge dewatering method of the present invention, it is effective without using an inorganic flocculant, but within a range not inhibiting the effect, for example, an inorganic flocculant such as aluminum sulfate, aluminum chloride, polyaluminum chloride, polyferrous sulfate, Polyferric sulfate, ferric chloride, etc. can be used.

The polymer flocculant and the organic coagulant in the present invention can be added as they are, or can be added to sludge after being dissolved and diluted with water to an arbitrary concentration. In the case of dissolution, a dissolution concentration of 0.05 to 0.5% by mass is generally applied. Moreover, although the addition rate with respect to sludge is 50-2000 ppm normally, it adjusts arbitrarily with object sludge.

  After the polymer flocculant and organic coagulant addition treatment in the present invention, a screw concentrator, a centrifugal concentrator, an elliptical concentrator, etc., a belt press, a centrifugal dehydrator, a screw press, a multi-disc dehydrator, a rotary press, A dehydrator such as a filter press can be arbitrarily applied.

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

First, polymer flocculant samples A to E used in the present invention were prepared and prepared. These compositions and physical properties are shown in Table 1. Next, organic coagulant samples 1 to 7 used in the present invention were prepared and prepared. These compositions and physical properties are shown in Table 2. Moreover, polyferric sulfate was prepared as an inorganic flocculant.

(Table 1)
DMQ: acryloyloxyethyltrimethylammonium chloride DMC: methacryloyloxyethyltrimethylammonium chloride AAM: acrylamide form; P: powder, EM: water-in-oil emulsion 0.2% by weight aqueous solution viscosity (AQV); polymer concentration is 0.2 Viscosity (mPa · s) measured at 25 ° C. when dissolved in water to a mass%
0.5 mass% salt aqueous solution viscosity (SLV); viscosity (mPa · s) measured at 25 ° C. when dissolved in 4 mass% saline so that the polymer concentration becomes 0.5 mass%.

(Table 2)
Form: AQ: aqueous polymer 0.2% by mass aqueous solution viscosity (AQV); viscosity measured at 25 ° C. when dissolved in water so that the polymer concentration is 0.2% by mass (mPa · s)
0.5 mass% salt aqueous solution viscosity (SLV); viscosity (mPa · s) measured at 25 ° C. when dissolved in 4 mass% saline so that the polymer concentration becomes 0.5 mass%.

(Example 1)
The sludge dewatering test of the polymer flocculant and the organic coagulant added prescription in the present invention was conducted. Sewage digested sludge (pH 7.6, SS content 15750 mg / L, organic matter amount 69.8% by mass / SS, coarse suspended matter amount 877 mg / L, electrical conductivity 620 mS / m, M-alkaliness 3358 mg / L, anion A quantity of 8.6 meq / L) was used. 200 mL of this sludge was collected in a poly beaker and used for the test. In the first liquid, 0.2 mass% of the polymer flocculant sample A in Table 1 was added at 270 ppm with respect to the sludge liquid. After stirring for 30 seconds at a stirring speed of 1000 rpm in the CST measuring device, the sludge was filtered through a 40 mesh filter cloth. Filtered for 60 seconds, added 100 ppm of 0.2% by weight of the organic coagulant sample solution in Table 2 to the second sludge liquid volume, and mixed and stirred 10 times with a spatula. Sludge filtered for 60 seconds with a cloth (# 202) was dehydrated at a press pressure of 3 kg / cm ² for 30 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 carried out on the same sludge as in Example 1 with the addition order and sample changed. The results are shown in Table 3.

(Table 3)

  For the examples in which the polymer flocculant was added to the first liquid and then the organic coagulant was added to the second liquid, the organic coagulant was added to the first liquid, the prescription with the polymer flocculant added to the second liquid, In the formulation in which molecular flocculants were added, the moisture content of the cake was high. In the formulation using both ferric sulfate and a polymer flocculant, it is necessary to increase the addition rate of polyferric sulfate in order to increase the dehydration efficiency to some extent.

(Example 2)
The sludge dewatering test of the polymer flocculant and the organic coagulant added prescription in the present invention was conducted. Sewage surplus sludge (pH 6.5, SS content 9500 mg / L, organic matter amount 81.6% by mass / SS, coarse suspended matter amount 393 mg / L, electrical conductivity 248 mS / m, M-alkaline degree 719 mg / L, anion Amount 4.1 meq / L) was used. 200 mL of this sludge was collected in a poly beaker and used for the test. In the first liquid, 0.2 ppm by mass of the sample C in Table 1 was added at 200 ppm to the liquid. After stirring for 30 seconds at a stirring rotation speed of 1000 rpm in a CST measurement device, the sludge was filtered with a 40 mesh filter cloth for 60 seconds. Then, 0.2 ppm by weight of the organic coagulant sample C shown in Table 2 was added to the second liquid with respect to the amount of residual sludge, and the mixture was stirred 10 times with a spatula, and then a nylon filter cloth (# 202 The sludge filtered for 60 seconds was dehydrated at a press pressure of 3 kg / cm ² for 30 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 carried out on the same sludge as in Example 2 with the addition order and sample changed. The results are shown in Table 4.

(Table 4)

  After adding the polymer flocculant to the first liquid and then adding the organic flocculant to the second liquid, the formulation of adding the organic flocculant to the first liquid, adding the polymer flocculant to the second liquid, The water content of the cake was higher in the formulation using both ferric sulfate and polymer flocculant.

(Example 3)
The sludge dewatering test of the polymer flocculant and the organic coagulant added prescription in the present invention was conducted. Sewage digested sludge (pH 7.3, SS content 10500 mg / L, organic matter amount 73.8% by mass / SS, coarse suspended matter amount 997 mg / L, electrical conductivity 717 mS / m, M-alkaline degree 3327 mg / L, anion Amount 7.2 meq / L) was used. 200 mL of this sludge was collected in a poly beaker and used for the test. In the first liquid, a 0.2 mass% solution of sample B in Table 1 was added at 230 ppm to the liquid. After stirring for 30 seconds at a stirring speed of 1000 rpm in a CST measurement device, the sludge was filtered for 60 seconds with a 40 mesh filter cloth. Then, 100 ppm or 150 ppm of the organic coagulant sample solution shown in Table 2 was added to the second liquid in the second liquid, and the mixture was stirred 10 times with a spatula, and then a nylon filter cloth (# 202), the sludge filtered for 60 seconds was dehydrated at a press pressure of 3 kg / cm ² for 30 seconds, and the moisture content of the cake (dried at 105 ° C. for 20 hours) was measured. Further, the amount of iron ions in the treated water was measured by atomic absorption photometry (JISK-0102 method) (raw sludge 7 ppm). These results are shown in Table 5.

(Comparative Example 3) A similar test was carried out on the same sludge as in Example 3 with the addition order and sample changed. The results are shown in Table 5.

(Table 5)

  After adding the polymer flocculant to the first liquid, and the example in which the organic flocculant was added to the second liquid, the formulation of adding the organic flocculant to the first liquid, the polymer flocculant added to the second liquid, The water content of the cake was higher in the formulation using both ferric sulfate and polymer flocculant. Moreover, when adding polyferric sulfate as a 2nd liquid, many iron ions were detected in treated water, and it turned out that an iron ion transfers to treated water.

Example 4
The sludge dewatering test of the polymer flocculant and the organic coagulant added prescription in the present invention was conducted. Industrial waste sludge as target sludge (pH 8.1, SS content 18000mg / L, organic matter amount 73.6% by mass / SS, coarse suspended matter amount 1042mg / L, electric conductivity 1676mS / m, M-alkalinity 8195mg / L, anion amount 11.8 meq / L) was used. 200 mL of this sludge was collected in a poly beaker and used for the test. In the first liquid, 0.2 ppm by mass of the sample E of Table E in Table 1 was added at 700 ppm to the liquid, and after stirring for 30 seconds at a stirring rotation speed of 1000 rpm in a CST measuring device, the sludge was filtered with a 40 mesh filter cloth for 60 seconds. Then, 0.2 ppm by weight of the organic coagulant sample of Table 2 above was added to the second liquid with respect to the amount of residual sludge, 100 ppm, after mixing and stirring 10 times with a spatula, nylon filter cloth (# 202) The sludge filtered for 60 seconds was dehydrated at a press pressure of 3 kg / cm ² for 30 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 carried out on the same sludge as in Example 4 with the addition order and sample changed. The results are shown in Table 6.

(Table 6)

  For the examples in which the polymer flocculant was added to the first liquid and then the organic coagulant was added to the second liquid, the organic coagulant was added to the first liquid, the polymer flocculant was added to the second liquid, In the prescription using ferric sulfate and the polymer flocculant, and the prescription adding the polymer flocculants, the moisture content of the cake was high.

After adding the polymer flocculant in the first liquid to the organic sludge in the present invention, by adding the organic flocculant in the second liquid, compared to the additive prescription other than the present invention and the inorganic flocculant combined prescription It was confirmed that the dehydration efficiency was improved.

Claims (4)

In the sludge dehydration method, the polymer flocculant is added to the organic sludge, mixed and stirred, and then the organic coagulant is added and mixed. A method for dewatering organic sludge, characterized in that the SLV of the organic coagulant is lower than that of the polymer flocculant when the viscosity measured at 25 ° C. when dissolved so as to be 0.5% by mass is SLV. The polymer flocculant is 10 to 100 mol% of a cationic monomer represented by the following general formula (1), 0 to 30 mol% of an anionic monomer represented by the following general formula (2), 2. The polymer flocculant composed of a polymer having 0 to 90 mol% of an ionic monomer as a constituent unit or one or more selected from amidine-based polymer flocculants, according to claim 1, Organic sludge dewatering method.
General formula (1)
R ₁ is hydrogen or a methyl group, R ₂ and R ₃ are alkyl groups or hydroxyalkyl groups having 1 to 3 carbon atoms, R ₄ is an alkyl or alkoxyl group having 1 to 3 carbon atoms, and an alkyl group or aryl group having 7 to 20 carbon atoms. , a is oxygen or NH, B represents an alkylene group having 2 to 4 carbon atoms, _{X 1} ^- represents respectively an anion.
Represents an alkylene group, X ₁ ^- represents respectively an anion.
General formula (2)
R ₅ is hydrogen, methyl group or carboxymethyl group, Q is SO ₃ ⁻ , C ₆ H ₄ SO ₃ ⁻ , CONHC (CH ₃ ) ₂ CH ₂ SO ₃ ⁻ , C ₆ H ₄ COO ⁻ or COO ⁻ , R ₆ represent respectively + _Y ^2, _{Y 1} or _{Y 2} is hydrogen or a cation and - is hydrogen or ^COO. The organic sludge dehydration method according to claim 1, wherein the organic coagulant has an SLV of 1 to 10 mPa · s. The organic sludge dehydration method according to claim 1 or 3, wherein the organic coagulant has a cation equivalent value of 3.0 to 22.0 meq / g at pH 7.