JP2008221171A - Method for dehydrating organic sludge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a more improved recipe in a sludge dehydration method using an inorganic flocculant or a polycondensable cationic substance, and an amphoteric water soluble polymer, in combination. <P>SOLUTION: One or more kinds selected from an inorganic flocculant, polycondensable cationic substance and polymerizable cationic substance with the weight average molecular weight of 10,000 to 100,000 is added to organic sludge, and then a (metha)acrylic crosslinkable anion-rich amphoteric polymer in which a charge involving rate is 10 to 50%, and also, the difference between an anionic monomer copolymerization rate A and a cationic monomer copolymerization rate C is 5 to 15 mol% (wherein, 20≤A≤50 and 25≤A+C≤95 are satisfied, and both the units of A and C are mol%), is added to the organic sludge, which is then dehydrated. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a sludge dewatering method, and more specifically, one or more selected from an inorganic coagulant, a polycondensation cationic substance, and a polymerization cationic substance having a weight average molecular weight of 10,000 to 2,000,000 with respect to organic sludge. Is added, the charge inclusion rate is 10% or more and 50% or less, and the difference between the anionic monomer copolymerization rate A and the cationic monomer copolymerization rate C is 5 to 15 mol%. The present invention relates to a method for dewatering organic sludge, characterized by adding an amphoteric water-soluble polymer (20 ≦ A ≦ 50, 25 ≦ A + C ≦ 95, both A and C being in mol%) and dewatering.

Various prescriptions for improving the sludge dewatering efficiency have been proposed. As a typical example, Japanese Patent Application Laid-Open No. 63-158200 discloses a specific ionicity after the pH is adjusted to 5 to 8 after the addition of the inorganic coagulant. An amphoteric polymer having a water content is added and dehydrated. Thereafter, the formulation using both inorganic and amphoteric polymers has been repeatedly improved. JP 7-256300 uses amphoteric polymers obtained by copolymerizing acrylate cationic monomers and methacrylate cationic monomers at a specific ratio. Yes. An example using a mixture of two amphoteric polymers has also been proposed (Japanese Patent Laid-Open No. 2003-117309). Furthermore, the crosslinkable polymer may show high performance specifically depending on the sludge, and has been studied for a long time. JP-A-61-293510 discloses a coagulation treatment method using a polymer having a high degree of crosslinking. It is disclosed. Japanese Patent Laid-Open No. 9-225499 is an example using a polymer having a relatively low degree of crosslinking. Recently, there is a polymer having a polyoxyalkylene chain (Japanese Patent Application Laid-Open No. 2005-68336).

Typical recipes aimed at improving the currently known sludge dewatering method are as described above, a combination of inorganic and amphoteric polymers, a mixture of two or more amphoteric polymers, a method using a crosslinked polymer, polyoxy A polymer having an alkylene chain.
Among these, a formulation in which two or more amphoteric polymers are mixed can be applied as a product form from powder to water-in-oil emulsion. It is also difficult to produce a cross-linkable water-soluble polymer into a polymer having the same structure with good reproducibility. Compared to this, it is relatively easy to produce a water-soluble polymer having a low degree of crosslinking. On the other hand, amphoteric water-soluble polymers have a wide range of uses such as combined use with inorganic coagulants, and in some cases, it is also possible to efficiently dehydrate hardly dewaterable sludge in the same manner as crosslinkable water-soluble polymers. To date, amphoteric water-soluble polymers and inorganic coagulants or low-molecular cationic polymerizations with low cross-linking and close differences between anionic monomer copolymerization rate and cationic monomer copolymerization rate There is no known sludge dewatering method that uses a combination of materials.

JP 63-158200 A Japanese Patent Laid-Open No. 7-256300 JP 2003-117309 A JP-A 61-293510 JP-A-9-225499 JP 2005-68336 A

An object of the present invention is to provide a further improved formulation in a sludge dewatering method using an inorganic coagulant or polycondensation cationic substance in combination with an amphoteric water-soluble polymer.

As a result of detailed studies to solve the above-mentioned problems, the inventors have reached the invention as described below. That is, the invention of claim 1 is a method comprising adding one or more selected from an inorganic coagulant, a polycondensation cationic substance, and a polymerization cationic substance having a weight average molecular weight of 10,000 to 2,000,000 to organic sludge. The rate is 10% or more and 50% or less, and the difference between the anionic monomer copolymerization rate A and the cationic monomer copolymerization rate C is 5 to 15 mol%. An organic sludge characterized by adding and dehydrating a crosslinkable anionic rich amphoteric polymer (20 ≦ A ≦ 50, 25 ≦ A + C ≦ 95, both A and C being in mol%) This is a dehydration method.

The invention according to claim 2 is the organic sludge dewatering method according to claim 1, wherein the amphoteric polymer flocculant is a water-in-oil emulsion or a dispersion in salt water.

The invention according to claim 3 is characterized in that the inorganic coagulant is at least one selected from aluminum sulfate, ferric chloride, polyaluminum chloride and polyiron sulfate. This is a sludge dewatering method.

The invention of claim 4 is characterized in that the polycondensed cationic substance is a reaction product of one or more amino compounds selected from aliphatic monoamines and aliphatic polyamines and epihalohydrins. The organic sludge dehydration method described in 1.

The invention according to claim 5 is characterized in that the polymeric cationic substance is one or more cationic substances selected from diallylammonium salt type or cationic (meth) acrylic type polymer, polyamidine type polymer, and polyalkyleneimine type substance. The method of dewatering organic sludge according to claim 1 or 2, characterized in that:

In the organic sludge method of the present invention, after adding one or more selected from an inorganic coagulant, a polycondensation cationic substance, and a polymerization cationic substance having a weight average molecular weight of 10,000 to 2,000,000 to the organic sludge, the charge inclusion rate Is 10% or more and 50% or less, and the difference between the anionic monomer copolymerization rate A and the cationic monomer copolymerization rate C is 5 to 15 mol%. Anionic rich amphoteric polymer (20 ≦ A ≦ 50, 25 ≦ A + C ≦ 95, both A and C are in mol%) and dehydrated.

The amphoteric polymer flocculant is preferably a water-in-oil emulsion or a salt water dispersion. Furthermore, the inorganic coagulant is preferably at least one selected from aluminum sulfate, ferric chloride, polyaluminum chloride, and polyiron sulfate. The polycondensed cationic substance is preferably a reaction product of one or more amino compounds selected from aliphatic monoamines and aliphatic polyamines and epihalohydrins. The polymerized cationic substance is preferably at least one selected from a cationic (meth) acrylic polymer, a polyamidine polymer, and a polyalkyleneimine substance.

The charge inclusion rate defined in the present invention is explained as follows. That is, in the cationic rich cross-linkable amphoteric water-soluble polymer, the charge inclusion rate is calculated as follows.
Charge inclusion rate [%] = (1−α / β) × 100
α is a 0.01% aqueous solution of a cross-linkable water-soluble ionic polymer adjusted to pH 4.0 with acetic acid by a PCD titrator (M &uuml; tek PCD 03, M &uuml; tek PCD-Two Titortor Version 2) manufactured by Mutec. Dropping liquid: 1 / 1000N
A titration amount obtained by titration with a potassium polyvinyl sulfonate aqueous solution, dropping rate: 0.05 ml / 10 sec, end point determination: 0 mV. β is added to a 0.01% aqueous solution of a crosslinkable water-soluble ionic polymer adjusted to pH 4.0 with acetic acid in an amount sufficient to neutralize the charge with a 1 / 400N aqueous potassium polyvinyl sulfonate solution, and sufficiently stirred. Similarly, titrate with a PCD titrator at a drop solution: 1 / 1000N diallyldimethylammonium chloride aqueous solution, drop rate: 0.05 ml / 10 sec, end point determination: 0 mV, and subtract this titration value from the blank value. . The blank value is a potassium polyvinyl sulfonate aqueous solution having the same concentration as that of the above sample adjusted to pH 4.0 with acetic acid. Similarly, using a PCD titration apparatus, dropping solution: 1 / 1000N diallyldimethylammonium chloride aqueous solution, dropping rate: 0.05 ml / 10 sec, end point determination: titration at 0 mv.

In the present invention, in the crosslinkable amphoteric water-soluble polymer that is anionic rich, the charge inclusion rate is calculated as follows.
Charge inclusion rate [%] = (1−α / β) × 100
α is a 0.01% aqueous solution of a cross-linkable water-soluble ionic polymer adjusted to pH 10.0 with ammonia using a PCD titration apparatus (M &uuml; tek PCD 03, M &uuml; tek PCD-Two Titortor Version 2) manufactured by Mutec. Dropping liquid: 1 / 1000N
This is a titration amount obtained by titration with diallyldimethylammonium chloride aqueous solution, dropping rate: 0.05 ml / 10 sec, end point determination: 0 mV. β is added to a 0.01% aqueous solution of a crosslinkable water-soluble ionic polymer adjusted to pH 10.0 with ammonia by adding a sufficient amount of 1 / 400N diallyldimethylammonium chloride aqueous solution to neutralize the charge, and sufficiently stirred. In the same manner, titrate with a PCD titrator at a drop solution: 1 / 1000N potassium polyvinylsulfonate aqueous solution, drop rate: 0.05 ml / 10 sec, end point determination: 0 mV, and subtract this titration value from the blank value. . The blank value is a diallyldimethylammonium chloride aqueous solution having the same concentration as that of the above sample adjusted to pH 10.0 with ammonia in the same manner by using a PCD titrator, dropping solution: 1/1000 N aqueous potassium polyvinylsulfonate solution, dropping rate: 0.05 ml / 10 sec, end point determination: titration at 0 mv.

As the (meth) acrylamide cross-linkable anionic rich amphoteric water-soluble polymer, a polymer having a charge encapsulation rate of 10% or more and 50% or less is used. A crosslinkable water-soluble polymer having a charge inclusion ratio in this range has a relatively low degree of crosslinking. The reason for using such a crosslinkable water-soluble polymer is that, as described in the background art, it is quite difficult to produce a polymer having a high degree of crosslinking with good reproducibility. Is relatively easy to manufacture. Therefore, in the present invention, it was studied to improve the performance as a sludge dehydrating agent by incorporating two elements of low cross-linking degree and amphotericity.

Among the ionic monomers used in the production of the (meth) acrylamide-based crosslinkable anionic rich amphoteric water-soluble polymer used in the present invention, the following are examples of cationic monomers. That is, polymers and copolymers such as dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, and methyldiallylamine are raised, and examples of quaternary ammonium group-containing polymers include the above-mentioned tertiary amino-containing monomer (Meth) acryloyloxyethyltrimethylammonium chloride, (meth) acryloyloxy 2-hydroxypropyltrimethylammonium chloride, (meth) acryloylaminopropyltrimethylammonium chloride, (Meth) acryloyloxyethyldimethylbenzylammonium chloride, (meth) acryloyloxy 2-hydroxypropyldimethylbenzylammonium chloride, (meth) acryloylaminopropyldimethylbenzylammonium Arm chloride, diallyl dimethyl ammonium chloride, and the like.

The anionic monomer may be either a sulfone group-containing monomer or a carboxyl group-containing monomer, and both may be used in combination. Examples of the sulfone group-containing monomer are vinyl sulfonic acid, vinyl benzene sulfonic acid, 2-acrylamido 2-methylpropane sulfonic acid, and the like. Examples of the carboxyl group-containing monomer include methacrylic acid, acrylic acid, itaconic acid, maleic acid, and p-carboxystyrene.

Examples of nonionic monomers used in producing the amphoteric water-soluble polymers (A) and (B) include (meth) acrylamide, N, N-dimethylacrylamide, vinyl acetate, acrylonitrile, methyl acrylate, (Meth) acrylic acid 2-hydroxyethyl, diacetone acrylamide, N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamidoacryloylmorpholine, acryloylpiperazine and the like.

Examples of the polyfunctional monomer having a plurality of vinyl groups used in the present invention include methylene bisacrylamide and ethylene glycol di (meth) acrylate. Examples of the crosslinkable monomer include thermally crosslinkable monomers such as N, N-dimethylacrylamide.

The addition amount of the polyfunctional monomer having a plurality of vinyl groups and / or the crosslinkable monomer with respect to the ionic monomer or the ionic monomer and the nonionic monomer is usually the above-mentioned single monomer. It is in the range of 0.005 to 0.1% by weight, preferably 0.01 to 0.1% by weight, based on the monomer mixture. In order to adjust the degree of polymerization, it is effective to use 0.01 to 3% by weight of isopropyl alcohol as a chain transfer agent in combination with the monomer.

The difference between the anionic monomer copolymerization rate and the cationic monomer copolymerization rate of the (meth) acrylamide amphoteric water-soluble polymer used in the present invention is 5-15. However, the anionic monomer copolymerization rate is 20 to 50 mol%, and the total copolymerization rate of the cationic monomer copolymerization rate and the anionic monomer copolymerization rate is 25 to 95 mol%. is there. This is because, in the present invention, when treating organic sludge, an amphoteric water-soluble polymer is added after the addition of an inorganic coagulant or polycondensation cationic substance, so that the anionic property is compared with the cationic monomer copolymerization rate. If the difference in the copolymerizable monomer copolymerization ratio is too large, the organic sludge modified with the inorganic coagulant or the polycondensation cationic substance is adversely affected. Moreover, even if an amphoteric water-soluble polymer is added, an appropriate floc is not generated, and the efficiency of sludge dehydration, which is the next step, is also reduced. Therefore, the feature of the present invention is that the difference between the cationic monomer copolymerization rate and the anionic monomer copolymerization rate is small.

In order to cope with hardly dehydrated sludge, a crosslinkable monomer is allowed to coexist when polymerizing the (meth) acrylamide amphoteric water-soluble polymer. That is, when there are few fibers and many particles with a small particle diameter like digested sludge and excess sludge, many particles are colloidal particles, and anion property is high and is disperse | distributing stably. For this reason, aggregation due to the cross-linking adsorption action by the linear polymer is hardly expressed. That is, it is considered that the floc formation does not occur while the particles remain dispersed without being hydrophobized. On the other hand, the cross-linked polymer has a denser form than the straight-chain polymer. Therefore, it is possible to neutralize the surface charge of the colloidal particles, and the linear polymer itself can be a nucleus of aggregation (in the present invention, the formation of flocs by the cross-linking adsorption action by the linear polymer is called aggregation, The formation of fine flocs mainly due to neutralization of the surface charge of hydrophilic particles such as is called condensation). As a result, a tightly-locked floc is formed, and the resistance to stirring is high, so that dehydration can be achieved efficiently even when dehydrating with a dehydrator. Furthermore, as a result of neutralizing the surface charge, the conditions under which the colloidal particles are hydrophobized and the water content decreases are in good condition. Therefore, it is considered that a crosslinked polymer is suitable for sludge having a large number of small particles. On the contrary, in the case of sludge having a large amount of fibers and large particles, aggregation due to the cross-linking adsorption action by the linear polymer is likely to occur.

The molecular weight of the (meth) acrylamide amphoteric water-soluble polymer used in the present invention is 3 million or more in terms of weight average molecular weight, preferably 5 million to 20 million. If it is less than 300, the cohesive force is insufficient, and preferably 5 million or more. Also, these values are the upper limits that can be industrially produced from the general molecular weight range of currently available polymer flocculants.

The crosslinkable anionic rich amphoteric water-soluble polymer of the present invention is an ionic monomer, or a polyfunctional monomer having a plurality of vinyl groups and / or an ionic monomer and a nonionic monomer and / or It can manufacture by copolymerizing the monomer mixture which consists of a crosslinkable monomer. The polymerization can be carried out by an ordinary polymerization method after preparing an aqueous solution in which these monomers are mixed.

As the polymerization method, after polymerization by aqueous solution polymerization, water-in-oil emulsion polymerization, water-in-oil dispersion polymerization, salt water dispersion polymerization, etc., it can be made into any product form such as aqueous solution, dispersion, emulsion or powder. . A preferred form is a water-in-oil emulsion polymerized product having a high concentration and a short dissolution time.

As a method for producing a water-in-oil polymer emulsion, a monomer mixture comprising an ionic monomer or an ionic monomer and a copolymerizable monomer is water, at least water-immiscible. An oily substance composed of a hydrocarbon, an amount effective for forming a water-in-oil emulsion, and at least one surfactant having HLB are mixed and stirred vigorously to form a water-in-oil emulsion, followed by polymerization. This is a method of synthesis.

Examples of oily substances composed of hydrocarbons used as dispersion media include paraffins, mineral oils such as kerosene, light oil, and middle oil, or hydrocarbon-based synthetics having characteristics such as boiling point and viscosity substantially in the same range as these. An oil or a mixture thereof may be mentioned. As content, it is the range of 20 mass%-50 mass% with respect to the water-in-oil type emulsion whole quantity, Preferably it is the range of 20 mass%-40 mass%.

Examples of at least one surfactant having an amount effective to form a water-in-oil emulsion and HLB are HLB 3-11 nonionic surfactants, specific examples of which include sorbitan monooleate Sorbitan monostearate, sorbitan monopalmitate and the like. The addition amount of these surfactants is 0.5 to 10% by weight, preferably 1 to 5% by weight, based on the total amount of the water-in-oil emulsion.

After the polymerization, a hydrophilic interfacial modifier called a phase inversion agent is added to make the emulsion particles covered with the oil film easy to become familiar with water, and to dissolve the water-soluble polymer therein. Dilute with and use for each application. Examples of hydrophilic surfactants are cationic surfactants and nonionic surfactants of HLB 9-15, such as polyoxyethylene polyoxypropylene alkyl ether systems and polyoxyethylene alcohol ether systems. is there.

The polymerization conditions are usually appropriately determined according to the monomer used and the copolymerization mol%, and the temperature is in the range of 0 to 100 ° C. In particular, when the water-in-oil emulsion polymerization method is applied, it is carried out in the range of 20 to 80 ° C, preferably 20 to 60 ° C. For the initiation of polymerization, a radical polymerization initiator is used. 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 include 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexanecarbonitrile), 2,2′-azobis (2-methylbutyronitrile), 2,2'-azobis (2-methylpropionate), 4,4-azobis (4-methoxy-2,4dimethyl) valeronitrile and the like.

Examples of water-soluble azo initiators include 2,2′-azobis (amidinopropane) dichloride, 2,2′-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] And 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. I can give you.

The polymerization concentration of the monomer is in the range of 20 to 50% by mass, and preferably in the range of 25 to 40% by mass. The concentration and temperature of the polymerization are appropriately determined depending on the composition of the monomer, the polymerization method, and the selection of the initiator. Set.

Examples of the inorganic coagulant used in the present invention include aluminum sulfate, ferric chloride, polyaluminum chloride, and polyiron sulfate. Preferably, one or more selected from aluminum sulfate, ferric chloride, polyaluminum chloride and polyiron sulfate are used.

The polycondensation cationic substance used in the present invention is a reaction product of one or more amino compounds selected from aliphatic monoamines and aliphatic polyamines and epihalohydrins. For example, it is a polycondensate of monomethylamine, monoethylamine, dimethylamine, diethylamine, or a polyalkylenepolyamine such as ethylenediamine, diethylenetriamine, or triethylenetetramine and an epihalohydrin such as epichlorohydrin. The molecular weight is several hundred or more in terms of weight average molecular weight, and preferably 1,000 to 100,000. If it is less than several hundreds, the cohesive force is insufficient, and therefore, preferably 1000 or more. Moreover, 100,000 is the upper limit of the polycondensate cationic substance that can be produced industrially at present.

The polymeric cationic substance used in the present invention is one or more cationic substances selected from diallylammonium salt or cationic (meth) acrylic polymers, polyamidine polymers, and polyalkyleneimine substances. That is, it is a polymer such as diallyldimethylammonium chloride, diallylmethylbenzylammonium chloride, or a copolymer with (meth) acrylamide. Alternatively, polymers and copolymers such as dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, and methyldiallylamine can be raised. Examples of quaternary ammonium group-containing polymers include the above-mentioned tertiary amino-containing monomer (Meth) acryloyloxyethyltrimethylammonium chloride, which is a quaternized product of methyl chloride or benzyl chloride, polymer such as (meth) acryloyloxy 2-hydroxypropyltrimethylammonium chloride, or (meth) acrylamide It is a copolymer. Furthermore, it is a polymer of ethyleneimine or a polyamidine polymer.

The inorganic coagulant used in the present invention is 0.05 to 1.0 mass%, preferably 0.1 to 0.5 mass%, based on the sludge SS content. The addition amount of the polycondensation-type cationic substance or the polymerization-type cationic substance having a weight average molecular weight of 10,000 to 1,000,000 is 0.005 to 0.05% by mass with respect to the sludge SS content, preferably 0.01 to 0.05% by mass. The addition amount of the (meth) acrylic crosslinkable anionic rich amphoteric water-soluble polymer is 0.5 to 5% by mass, preferably 0.1 to 0.3% by mass, based on the sludge SS content. . Applicable sludge is surplus sludge generated by biological treatment such as paper wastewater, chemical industry wastewater, food industry wastewater, etc., or organic sludge such as raw sludge, mixed raw sludge, surplus sludge, digested sludge, etc. Such as dehydration.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist. In the examples, “%” means “% by mass” unless otherwise specified.

(Synthesis Example 1) In a reaction vessel equipped with a stirrer and a temperature controller, 5.0 g of sorbitan monooleate was charged and dissolved in 130 g of isoparaffin having a boiling point of 190 ° C to 230 ° C. Separately, 80.5 g of 80% aqueous solution of acryloyloxyethyltrimethylammonium chloride (hereinafter abbreviated as DMQ), 205.2 g of 50% aqueous solution of acrylamide (abbreviated as AAM), 60% aqueous solution of acrylic acid, 53.3 g, methylenebisacrylamide 0.1 % Aqueous solution 0.8 g (based on monomer 4 ppm), isopropyl alcohol 0.76 g (based on monomer 0.4% by mass), and ion-exchanged water 119.1 g were collected, mixed and completely dissolved. Thereafter, the oil and the aqueous solution were mixed, and stirred and emulsified with a homogenizer at 1000 rpm for 15 minutes. The monomer composition at this time is DMQ / AAM / AAC = 15/65/20 (mol%).

The obtained emulsion was kept at a temperature of the monomer solution at 30 to 33 ° C. and purged with nitrogen for 30 minutes, and then dioxane of dimethyl-2,2-azobisisobutyrate (V-601, manufactured by Wako Pure Chemical Industries). 0.4 g of 10% by weight solution (0.02% by weight of monomer) was added to initiate the polymerization reaction. The reaction was completed at a reaction temperature of 32 ± 2 ° C. for 12 hours to complete the reaction. After the polymerization, 5.0 g of polyoxyethylene polyoxypropylene alkyl ether (1% by weight with respect to the liquid) was added to and mixed with the resulting water-in-oil emulsion as a phase inversion agent. Then, when the product viscosity was measured with a B-type viscometer, it was 350 mPa · s. The charge inclusion rate determined by the colloid titration method and the above formula was 40.5%. This is used as a sample for a dehydration test and is referred to as Sample-1.

(Synthesis Example 2) Sample-2 to Sample-12 were synthesized in the same manner as in Synthesis Example 1 with the compositions shown in Table-1. The results are shown in Table-1.

(Comparative Synthesis Example 1) 5.0 g of sorbitan monooleate was charged and dissolved in 130 g of isoparaffin having a boiling point of 190 ° C. to 230 ° C. in a reaction vessel equipped with a stirrer and a temperature controller. Separately, 80.5 g of 80% aqueous solution of acryloyloxyethyltrimethylammonium chloride (hereinafter abbreviated as DMQ), 205.2 g of 50% aqueous solution of acrylamide (abbreviated as AAM), 60% aqueous solution of acrylic acid, 53.3 g, 0.76 g of isopropyl alcohol ( 0.4% by mass of monomer) and 119.1 g of ion-exchanged water were each collected, mixed and completely dissolved. Thereafter, the oil and the aqueous solution were mixed, and stirred and emulsified with a homogenizer at 1000 rpm for 15 minutes. The monomer composition at this time is DMQ / AAM / AAC = 15/65/20 (mol%).

The obtained emulsion was kept at a temperature of the monomer solution at 30 to 33 ° C. and purged with nitrogen for 30 minutes, and then dioxane of dimethyl-2,2-azobisisobutyrate (V-601, manufactured by Wako Pure Chemical Industries). 0.4 g of 10% by weight solution (0.02% by weight of monomer) was added to initiate the polymerization reaction. The reaction was completed at a reaction temperature of 32 ± 2 ° C. for 12 hours to complete the reaction. After the polymerization, 5.0 g of polyoxyethylene polyoxypropylene alkyl ether (1% by weight with respect to the liquid) was added to and mixed with the resulting water-in-oil emulsion as a phase inversion agent. Then, when the product viscosity was measured with a B-type viscometer, it was 350 mPa · s. The charge inclusion rate determined by the colloid titration method and the above formula was 40.5%. This is used as a sample for a dehydration test and is referred to as Comparative-1.

(Comparative Synthesis Example 2) Comparative-2 to Comparative-7 were synthesized in the same manner as in Synthesis Example 1 with the compositions shown in Table-1. The results are shown in Table-1.

(Table 1)
DMQ: acryloyloxyethyltrimethylammonium chloride, AAM: acrylamide, AAC: acrylic acid, emulsion viscosity (25 ° C.); mPa · s, addition amount of crosslinkable monomer; monomer mass%, charge inclusion rate:%

For excess sludge generated from a sewage treatment plant (sludge property is pH 6.6, SS: 15500 mg / L), a coagulation filtration test and a squeeze test were conducted for a centrifugal dehydrator. This sludge has a 200 mesh-on residue as low as 17.3% by mass, an organic component of 70.4% by mass with respect to SS, a large proportion of organic component, and sludge particles are also small, so that it is difficult to dewater. Enter into the classification. After 200 ml of sludge was put into a 300 ml polypropylene beaker, 300 ppm of dimethylamine / pentaethylenehexamine / epichlorohydrin reaction product as a polycondensation cationic substance was added to the sludge SS and stirred at 1000 rpm for 15 seconds. The dissolved solution of -1 to Sample-12 was added with 0.7% of sludge SS, and the sludge was agglomerated by stirring at 1000 rpm for 30 seconds. Thereafter, after observing the size of the floc, the filtration rate was examined with a beaker with a 60 mesh filter cloth. Further, the water content of the dehydrated cake was determined after press-dehydrating the aggregate after filtration for 30 seconds at a pressing pressure of 1 kgf / cm 2. These results are shown in Table 2.

(Comparative Test 1) Tests were performed on Comparative-1 to Comparative-7 in Table 1 by the same test operation. These results are shown in Table 2.

As can be seen from the results, the charge inclusion rate is lower than 10 in comparison-1 to comparison-3, and even if the charge inclusion rate is in the range of 10-50, the anionic monomer copolymerization rate and the cationic monomer amount It can be seen that the comparisons −4 to −7 where the difference in the body copolymerization ratio is greater than 15 are all ineffective.

(Table 2)
Flock diameter: mm, filtrate amount: mL, water content: mass%, chemical injection amount: sludge dispersion

For excess sludge generated from the slaughterhouse (sludge property is pH 6.2, SS: 19000 mg / L), a coagulation filtration test and a squeeze test were conducted for a centrifugal dehydrator. The sludge has a relatively low 200-mesh-on residue of 29.8% by mass and is relatively hardly dehydrated sludge. After 200 ml of sludge was put in a 300 ml polypropylene beaker, 2500 ppm of polyaluminum chloride as an inorganic coagulant was added to the sludge SS and stirred at 1000 rpm for 15 seconds, and then the solutions of Sample-1 to Sample-12 in Table 1 were added. Sludge SS was added at 0.5%, and sludge was agglomerated by stirring at 1000 rpm for 30 seconds. Thereafter, after observing the size of the floc, the filtration rate was examined with a beaker with a 60 mesh filter cloth. Further, the water content of the dehydrated cake was determined after press-dehydrating the aggregate after filtration for 30 seconds at a pressing pressure of 1 kgf / cm 2. These results are shown in Table 3.

(Comparative Test 2) Tests were performed on Comparative-1 to Comparative-7 in Table 1 by the same test operation. These results are shown in Table 3.

As can be seen from the results, the charge inclusion rate is lower than 10 in comparison-1 to comparison-3, and even if the charge inclusion rate is in the range of 10-50, the anionic monomer copolymerization rate and the cationic monomer amount It can be seen that the comparisons −4 to −7 where the difference in the body copolymerization ratio is greater than 15 are all ineffective.

(Table 3)
Flock diameter: mm, filtrate amount: mL, water content: mass%, chemical injection amount: sludge dispersion

Claims (5)

After adding at least one selected from an inorganic coagulant, a polycondensation cationic substance, and a polymerization cationic substance having a weight average molecular weight of 10,000 to 2,000,000 to organic sludge, the charge encapsulation rate is 10% or more, 50% (Meth) acrylic crosslinkable anionic rich amphoteric water-soluble in which the difference between the anionic monomer copolymerization ratio A and the cationic monomer copolymerization ratio C is 5 to 15 mol% A method for dewatering organic sludge, comprising adding a polymer (provided that 20 ≦ A ≦ 50, 25 ≦ A + C ≦ 95, and both A and C are in mol%) and dewatering. 2. The organic sludge dewatering method according to claim 1, wherein the amphoteric polymer is a water-in-oil emulsion or a salt water dispersion. 3. The method of dewatering organic sludge according to claim 1, wherein the inorganic coagulant is at least one selected from aluminum sulfate, ferric chloride, polyaluminum chloride, and polyiron sulfate. The dehydration of organic sludge according to claim 1 or 2, wherein the polycondensation cationic substance is a reaction product of one or more amino compounds selected from aliphatic monoamines and aliphatic polyamines and epihalohydrins. Method. The polymeric cationic substance is one or more cationic substances selected from diallylammonium salt-based or cationic (meth) acrylic polymers, polyamidine polymers, and polyalkyleneimine substances. The method for dewatering organic sludge according to claim 1 or 2.