JP2014024044A - Cation high polymer coagulant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high polymer coagulant superior in the dehydration ratio in a dehydration process of organic sludge and concentration efficiency in a concentration process before this dehydration process, even in a little addition amount (the addition ratio).SOLUTION: The present invention uses the cation high polymer coagulant including a cation high polymer (A) having salt viscosity of 130-210 mPa s and a cation high polymer (B) having salt viscosity of 5-60 mPa s. The cation high polymer (A) has a colloid equivalent value (CEa) of 1.2-4.8 meq./g, and the cation high polymer (B) has a colloid equivalent value (CEb) of 1.7-4.9 meq./g, and the ratio (CEb/CEa) of these colloid equivalent values is desirably 0.5-2. Low molecular ammonium salt (T) is further desirably included.

Description

  The present invention relates to a cationic polymer flocculant, a method for dewatering and concentrating organic sludge. More specifically, the present invention relates to a cationic polymer flocculant that is most suitable for concentration and dehydration of organic sludge (particularly difficult-to-filter organic sludge) generated from microbial treatment such as sewage, human waste and / or industrial wastewater.

Conventionally, organic sludge generated from microbial treatment such as sewage, human waste or industrial wastewater is dehydrated by adding a polymer flocculant and dewatering with a dehydrator (eg, centrifugal dehydrator, belt press, screw press, filter press). After making a cake, a method of incineration and disposal as incineration ash is widely performed. In this case, since it is desired to reduce the water content of the dehydrated cake as much as possible in order to reduce fuel costs during incineration, a high-performance polymer flocculant for dehydration is required.
In response to such a demand, a cationic polymer flocculant having a crosslinked structure in the molecule (Patent Document 1), a cationic polymer flocculant having a long-chain hydrophilic group in the molecule (Patent Document 2), an ion equivalent of A mixture of two or more different amphoteric polymer flocculants (Patent Document 3), a mixture of a cationic polymer flocculant having a molecular weight of 1 million to 3 million and a cationic polymer flocculant having a molecular weight of 3 million or more (Patent Document 4) ) Etc. have been proposed.

  In order to increase the moisture content of the dehydrated cake, it is effective to concentrate the sludge in advance before dehydration. The sludge is stored in a concentration tank in advance and concentrated before dehydration (for example, gravity concentration). , Pressure levitation concentration and centrifugal concentration). However, in recent years, due to an increase in the organic content in sludge, there are increasing cases where sufficient concentration is difficult by such a method, and there is a demand for a high-performance polymer flocculant for concentration. In order to meet this need, as a polymer flocculant for concentration, a water-in-oil emulsion cation or a mixture of amphoteric polymer flocculants having different molecular weights (Patent Document 5), a specific amphoteric polymer flocculant and an anionic polymer Mixture of flocculant (Patent Document 6), mixture of specific cationic polymer flocculant and amphoteric polymer flocculant (Patent Document 7), two or more amphoteric polymers having different ion equivalents and specific cationic polymer A mixture (Patent Document 8) and the like have been proposed.

JP 2004-59719 A JP 2004-99668 A JP 2002-177706 A Japanese Patent Publication No. 05-047280 JP 2005-177670 A JP 2003-117600 A JP 2002-177709 A JP 2004-210986 A

However, these proposed methods do not always give sufficient results, that is, even if a large amount of a polymer flocculant is added to the concentration / dehydration of recently difficult-to-concentrate organic sludge. There is a problem that it is still insufficient.
An object of the present invention is to provide a polymer flocculant excellent in the dewatering rate in the dewatering step of organic sludge and the concentration efficiency in the concentration step before this dewatering step even with a small addition amount (addition rate). is there.

  The characteristics of the cationic polymer flocculant of the present invention include a cationic polymer (A) having a salt viscosity of 130 to 210 mPa · s and a cationic polymer (B) having a salt viscosity of 5 to 60 mPa · s. The point is summarized.

  The feature of the organic sludge dewatering method of the present invention is summarized in that the above cationic polymer flocculant is added to the organic sludge for dehydration.

  The feature of the organic sludge concentration method of the present invention is summarized in that the above cationic polymer flocculant is added to organic surplus sludge or organic sludge containing the organic sludge and concentrated.

The cationic polymer flocculant of the present invention can dehydrate and concentrate organic sludge with an excellent dehydration rate and excellent concentration efficiency even with a small addition amount (addition rate).
Therefore, the combustion energy at the time of incineration of the dehydrated cake can be minimized, and the amount of global warming gas (carbon dioxide) generated at the time of combustion can also be reduced.

  In the present invention, the organic sludge applicable to dehydration / concentration is not limited as long as it is sludge generated by biological treatment of wastewater (organic sludge), but microbial treatment such as sewage, human waste and / or industrial wastewater. Organic sludge generated from sewage and / or sewage is more preferable. Particularly preferred as organic sludge applicable to concentration is organic sludge containing excess sludge, and particularly preferred as organic sludge applicable to dewatering is organic sludge containing digested sludge.

  The cationic polymer (A) and the cationic polymer (B) include a cationic polymer having the following cationic monomer as an essential constituent monomer.

  As the cationic monomer, an amine salt of an amino group-containing compound {hydrochloride, sulfate, phosphate, etc.) and an amino group-containing compound are converted into a quaternizing agent (methyl chloride, ethyl bromide, benzyl chloride, dimethyl sulfate, and Quaternary ammonium salts {methyl chloride salts, dimethyl sulfate salts, benzyl chloride salts, etc.} quaternized with dimethyl carbonate or the like).

  As the amino group-containing compound, amino group-containing (meth) acrylate {N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate and N, N-diethylaminopropyl (meth) acrylate etc.}, amino group-containing (meth) acrylamide {N, N-dimethylaminoethyl (meth) acrylamide etc.} or amino group-containing vinyl compound {p-aminostyrene, 2-vinylpyridine , Vinylaniline and (meth) allylamine, etc.}.

  The cationic polymer may contain a nonionic monomer as a constituent monomer in addition to the cationic monomer.

  Nonionic monomers include (meth) acrylate {hydroxyethyl (meth) acrylate and diethylene glycol mono (meth) acrylate, etc.}, (meth) acrylamide {(meth) acrylamide, N-methyl (meth) acrylamide, N-isopropyl (Meth) acrylamide and N-methylol (meth) acrylamide etc.} and other vinyl monomers {acrylonitrile and N-vinyl-2-pyrrolidone etc.} and the like.

  Of the cationic polymers, a quaternary ammonium salt of dialkylaminoethyl (meth) acrylate is preferably used as an essential constituent monomer, and more preferably a quaternary ammonium salt of methyl chloride of dimethylaminoethyl acrylate (ie, A polymer comprising trimethylammonioethyl acrylate) as a constituent monomer.

  The cationic polymer may be obtained by homopolymerizing the above cationic monomer, copolymerizing a plurality of types of cationic monomers, and further using a nonionic monomer as a copolymerizable monomer. May be included. Further, a water-insoluble monomer or a crosslinkable monomer may be copolymerized. Furthermore, you may copolymerize an anionic monomer in the range which does not impair the effect of this invention (about 3 mol% or less with respect to the number-of-moles of all the monomers).

  Examples of the water-insoluble monomer include methyl (meth) acrylate, ethyl (meth) acrylate, ω-methoxyethyl (meth) acrylate, ω-methoxypropyl (meth) acrylate, and the like.

  As the crosslinkable monomer, crosslinkable (meth) acrylamide {N, N-methylenebisacrylamide, etc.}, crosslinkable (meth) acrylate {ethylene glycol di (meth) acrylate, pentaerythritol (poly) (2-4) (Meth) acrylates, etc.], crosslinkable vinyl monomers {divinylamine, trivinylamine, divinyl ether, ethylene glycol divinyl ether, polyethylene glycol (degree of polymerization 2-50) divinyl ether, trimethylolpropane trivinyl ether, glycerin divinyl ether And pentaerythritol tetravinyl ether, etc.], crosslinkable (meth) allyl monomer {di (meth) allylamine, N-alkyl (1-20 carbon atoms) di (meth) allylamine, ethylene glycol di (meth) allyl ether, polyester Lenglycol (degree of polymerization 2-50) di (meth) allyl ether, glycerin di (meth) allyl ether, pentaerythritol tetra (meth) allyl ether and tetraallyloxyethane} and thermally crosslinkable monomer {ethylene glycol di Glycidyl ether, polyethylene glycol diglycidyl ether, glycerin triglycidyl ether and the like} and the like.

  When the nonionic monomer is copolymerized, the use ratio (mol%) of the cationic polymer (A) is preferably 17 to 90, more preferably 21 based on the number of moles of all monomers. -89.5, particularly preferably 25-89. In addition, for the cationic polymer (B), the use ratio (mol%) of the nonionic monomer is preferably 13 to 85, more preferably 29 to 84, particularly based on the number of moles of all monomers. Preferably it is 44-80.

  When copolymerizing a water-insoluble monomer, the use ratio (mol%) is preferably 0.1 to 40, more preferably 0.2 to 20, particularly based on the number of moles of all monomers. Preferably it is 0.5-10.

  When copolymerizing a crosslinkable monomer, the use ratio (mol%) is preferably from 0.0001 to 5, more preferably from 0.001 to 1, based on the number of moles of all monomers. Preferably it is 0.01-0.5.

  The salt viscosity (mPa · s) of the cationic polymer (A) is preferably 130 to 210, more preferably 135 to 190, and particularly preferably 140 to 170. Within this range, the dehydration rate and concentration efficiency are further improved.

  5-60 are preferable, as for the salt viscosity (mPa * s) of a cationic polymer (B), More preferably, it is 10-55, Most preferably, it is 16-50. Within this range, the dehydration rate and concentration efficiency are further improved.

The salt viscosity (mPa · s) means a rotational viscosity obtained by measuring a solution obtained by dissolving a sample in a 4 wt% sodium chloride aqueous solution at a concentration of 0.5 wt%, and is a value measured as follows.
With a stirrer composed of a stirrer with a tachometer, a stirrer shaft and three propeller blades (diameter 5 cm), while stirring 286.5 g of ion-exchanged water in a 500 ml glass beaker (rotation speed 450 rpm), precisely weigh it. After adding 1.500 g of the measured sample so as not to become mamako, dissolve it by stirring at 20 ° C. for 2 hours, add 12.00 g of sodium chloride, and further stir at 20 ° C. for 30 minutes. The obtained solution is transferred to a 200 ml tall beaker, adjusted to 25 ° C. ± 0.5 ° C. in a constant temperature water bath, and the rotational viscosity is measured in accordance with JIS K5101-6-2: 2004.

  The colloid equivalent value (CEa; meq./g) of the cationic polymer (A) is not particularly limited, but is preferably 1.2 to 4.8, more preferably 1.25 to 4.7, particularly preferably. 1.3 to 4.6, most preferably 1.5 to 4.4. Within this range, the dehydration rate and concentration efficiency are further improved.

  The colloid equivalent value (CEb; meq./g) of the cationic polymer (B) is not particularly limited, but is preferably 1.7 to 4.9, more preferably 1.8 to 4.8, particularly preferably. 2 to 4.7, most preferably 2.5 to 4.6. Within this range, the dehydration rate and concentration efficiency are further improved.

  The ratio (CEb / CEa) between the colloid equivalent value (CEa) of the cationic polymer (A) and the colloid equivalent value (CEb) of the cationic polymer (B) is preferably 0.5 to 2, more preferably 0.8. It is 55 to 1.9, particularly preferably 0.6 to 1.8, and most preferably 0.6 to 1.7. Within this range, the dehydration rate and concentration efficiency are further improved.

  The colloid equivalent value (meq./g) is a value measured at pH 4.0 by a colloid titration method (a method of titrating with a potassium polyvinyl sulfate solution).

There is no restriction | limiting in the manufacturing method of cationic polymer (A), It can manufacture by a well-known method (For example, Unexamined-Japanese-Patent No. 1-138210, Unexamined-Japanese-Patent No. 2004-181449, and Unexamined-Japanese-Patent No. 2000-189713 are references.) .
In the method for producing the cationic polymer (A), the method for bringing the salt viscosity within the above range includes polymerization conditions (amount of catalyst, polymerization temperature, type / addition amount of chain transfer agent, type of crosslinkable monomer, And the like, and the like. Moreover, as a method of making colloid equivalent value into said range, the method of adjusting the kind of monomer, a monomer ratio, etc. is mentioned.

There is no restriction | limiting in the manufacturing method of a cationic polymer (B), It can manufacture by a well-known aqueous solution polymerization method (for example, Unexamined-Japanese-Patent No. 2000-189713 becomes reference).
In the method for producing the cationic polymer (B), the method for bringing the salt viscosity within the above range includes polymerization conditions (amount of catalyst, polymerization temperature, type / addition amount of chain transfer agent, type / addition amount of crosslinkable monomer). Etc.) and the like. Moreover, as a method of making colloid equivalent value into said range, the method of adjusting the kind of monomer, a monomer ratio, etc. is mentioned.

  The content (% by weight) of the cationic polymer (A) is preferably 15 to 70, more preferably 20 to 50, particularly preferably based on the weight of the cationic polymer (A) and the cationic polymer (B). 25-50. Within this range, the dehydration rate and concentration efficiency are further improved.

  The content (% by weight) of the cationic polymer (B) is preferably 30 to 85, more preferably 50 to 80, particularly preferably based on the weight of the cationic polymer (A) and the cationic polymer (B). 50-75. Within this range, the dehydration rate and concentration efficiency are further improved.

Even if only the cationic polymer (A) is used as a polymer flocculant and mixed with organic sludge, the mixing property is poor, the organic sludge does not aggregate, and the dehydration rate and the concentration efficiency are remarkably deteriorated. On the other hand, when only the cationic polymer (B) is used as the polymer flocculant, a large amount of addition is required, and a large amount of the polymer flocculant is added for concentration / dehydration of difficult-to-concentrate organic sludge in recent years. However, there is a problem that it is still insufficient.
By using the cationic polymer flocculant of the present invention, a dense and high-strength aggregate is formed quickly and uniformly even with a small addition amount (addition rate). Concentration efficiency can be achieved.

  The cationic polymer flocculant of the present invention preferably further contains a low molecular ammonium salt (T).

  As low molecular ammonium salt (T), what is comprised from at least 1 sort (s) chosen from the group which consists of inorganic ammonium salt, inorganic guanidine salt, and C1-C6 organic acid ammonium salt is contained.

  Examples of the inorganic ammonium salt include ammonium sulfate, ammonium hydrogen sulfate, ammonium nitrate, ammonium chloride, ammonium phosphate, ammonium hydrogen phosphate, and ammonium sulfamate.

  Examples of inorganic guanidine salts include guanidine sulfate, guanidine carbonate, guanidine sulfamate, guanidine hydrochloride, and guanidine phosphate.

  Examples of the organic acid ammonium salt having 1 to 6 carbon atoms include ammonium formate salt, ammonium acetate salt, ammonium oxalate salt, ammonium citrate salt, ammonium malate salt, ammonium tartrate salt and ammonium ascorbate.

  When the low molecular ammonium salt (T) is contained, the content (% by weight) of the low molecular ammonium salt (T) is that of the cationic polymer (A), the cationic polymer (B), and the low molecular ammonium salt (T). Based on weight, 5-40 are preferable, More preferably, it is 8-35, Most preferably, it is 15-25. Within this range, the dehydration rate and concentration efficiency are further improved.

  In this case, the content (% by weight) of the cationic polymer (A) and the cationic polymer (B) is the weight of the cationic polymer (A), the cationic polymer (B), and the low molecular ammonium salt (T). Is preferably 60 to 95, more preferably 65 to 92, and particularly preferably 75 to 85. Within this range, the dehydration rate and concentration efficiency are further improved.

  In the cationic polymer flocculant of the present invention, in addition to the cationic polymer (A), the cationic polymer (B) and the low molecular ammonium salt (T), other additives, as long as the effects of the present invention are not inhibited, For example, surfactants {polyoxyethylene nonylphenyl ether and dioctyl sulfosuccinate soda, etc.}, blocking agents {polyethylene oxide modified silicone and polyethylene oxide / polypropylene oxide modified silicone, etc.}, and antioxidants {hydroquinone, methoxyhydroquinone, catechol , Cuperone, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, bis (1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, 4-benzoyloxy-2,2, 6,6-tetramethyl-4-pi Lysine-1-oxyl, 2-mercaptobenzothiazole, thiourea, tetramethylthiuram disulfide, dimethyldithiocarbamic acid, sodium piperazine-bis-dithiocarbamate, sodium sulfite, sodium thiosulfate, triphenyl phosphite, triethyl phosphite Sodium phosphate, sodium hypophosphite, urea, etc.} and the like.

  In the cationic polymer flocculant of the present invention, the cationic polymer (A) and the cationic polymer (B), and if necessary, the low molecular ammonium salt (T) and / or other additives are uniformly mixed. For example, the production method is not limited and can be produced by a known method.

  The organic sludge dehydration method of the present invention is not limited as long as the above-described cationic polymer flocculant is added to the organic sludge or the concentrated liquid described later for dehydration, and any known method can be applied.

  The concentration (% by weight) of the aqueous solution of the cationic polymer flocculant is preferably 0.05 to 0.5, more preferably 0.1 to 0.35, and particularly preferably 0.15 to 0.3.

  Even if a solution obtained by dissolving the cationic polymer (A) in water and a solution obtained by dissolving the cationic polymer (B) in water are separately added to the organic sludge, the effect of the present invention cannot be obtained. This is presumed that when these are dissolved in water, the polymer chain derived from the cationic polymer (A) and the cationic polymer (B) have some influence on each other.

  The dehydrator is not limited as long as it can be dehydrated, and can be applied to any of a non-filter cloth dehydrator (such as a centrifugal dehydrator, a screw press and a capillary dehydrator) and a filter cloth dehydrator (such as a belt press and a filter press). Of these, centrifugal dehydrators and screw presses are effective.

  When the cationic polymer flocculant is used for dehydration, the addition rate (wt% / TS) of the cationic polymer flocculant can be determined as appropriate depending on the type and equipment of the organic sludge. (TS) The weight is preferably 0.3 to 3% by weight, more preferably 0.4 to 2.5% by weight, particularly preferably 0.5 to 2.5% by weight, and most preferably 0.5 to 1%. .4% by weight. Within this range, an excellent dehydration rate can be expressed.

  The solid content (TS), suspended solid amount (SS) and organic content of organic sludge are measured according to the method described in the Sewerage Test Method (Volume 2) (issued by the Japan Sewerage Association, 1997). That is, the solid content of the organic sludge is obtained by drying in a smooth air dryer at 105 ° C. until a constant weight is obtained, and measuring the weight after drying.

  As a method for concentrating the organic sludge of the present invention, there is no limitation as long as the above-mentioned cationic polymer flocculant is added to the organic sludge and concentrated prior to the dehydration method, and a known method can be applied.

  Even if a solution obtained by dissolving the cationic polymer (A) in water and a solution obtained by dissolving the cationic polymer (B) in water are separately added to the organic sludge, the effect of the present invention cannot be obtained. This is presumed that when these are dissolved in water, the polymer chain derived from the cationic polymer (A) and the cationic polymer (B) have some influence on each other.

  The concentrator can be applied to any of granulating concentrators, pressurized flotation concentrators, centrifugal concentrators, belt concentrators, screens and the like as long as it can be concentrated. Of these, a granulating concentrator, a centrifugal concentrator, and a belt concentrator are effective.

  When the cationic polymer flocculant is used for concentration, the addition rate (wt% / SS) of the cationic polymer flocculant can be determined as appropriate depending on the type and equipment of the organic sludge. The amount is preferably 0.1 to 0.5% by weight (SS) weight, more preferably 0.2 to 0.45% by weight, particularly preferably 0.2 to 0.4% by weight, and most preferably 0.8. 2 to 0.3% by weight.

  In the organic sludge treatment step, the cationic polymer flocculant of the present invention is preferably used in both the dehydration step and the concentration step, but may be used in either one. And when using for both of these spin-drying | dehydration processes and a concentration process, you may use a respectively different kind of cationic polymer flocculent, and may use the same kind of cationic polymer flocculant.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to this. Unless otherwise specified, “part” means “part by weight” and “%” means “% by weight”.

  Cationic polymers (A1) to (A4), cationic polymers (B1) to (B4), cationic polymers (C1) and cationic polymers (D2) used in Examples and Comparative Examples are as follows. .

  Cationic polymer (A1): Copolymer of methyl chloride quaternized product of dimethylaminoethyl acrylate (trimethylammonioethyl acrylate chloride: 35 mol%) and acrylamide (65 mol%) (salt viscosity 170 mPa · s, colloid equivalent) Value 3 meq./g)

  Cationic polymer (A2): Copolymer of methyl chloride quaternized dimethylaminoethyl acrylate (trimethylammonioethyl acrylate: 45 mol%) and acrylamide (55 mol%) (salt viscosity 140 mPa · s, colloid equivalent) Value 3.5 meq./g)

  Cationic polymer (A3): Copolymer of methyl chloride quaternized product of dimethylaminoethyl acrylate (trimethylammonioethyl acrylate: 68 mol%) and acrylamide (32 mol%) (salt viscosity 130 mPa · s, colloid equivalent) Value 4.4 meq./g)

  Cationic polymer (A4): Copolymer of methyl chloride quaternized product of dimethylaminoethyl acrylate (trimethylammonioethyl acrylate chloride: 13 mol%) and acrylamide (87 mol%) (salt viscosity 147 mPa · s, colloid equivalent) Value 1.5 meq./g)

  Cationic polymer (B1): Copolymer of dimethylaminoethyl acrylate methyl chloride quaternized product (trimethylammonioethyl acrylate chloride: 62 mol%) and acrylamide (38 mol%) (salt viscosity 50 mPa · s, colloid equivalent) (Value 4.2 meq./g)

  Cationic polymer (B2): Copolymer of methyl chloride quaternized dimethylaminoethyl acrylate (trimethylammonioethyl acrylate: 75 mol%) and acrylamide (25 mol%) (salt viscosity 16 mPa · s, colloid equivalent) Value 4.6 meq./g)

  Cationic polymer (B3): Copolymer of methyl chloride quaternized product of dimethylaminoethyl acrylate (trimethylammonioethyl acrylate chloride: 35 mol%) and acrylamide (65 mol%) (salt viscosity 35 mPa · s, colloid equivalent) Value 3 meq./g)

  Cationic polymer (B4): Copolymer of dimethylaminoethyl acrylate methyl chloride quaternized product (trimethylammonioethyl acrylate chloride: 25 mol%) and acrylamide (75 mol%) (salt viscosity 30 mPa · s, colloid equivalent) Value 2.5 meq./g)

  Cationic polymer (C1): Copolymer of dimethylaminoethyl acrylate methyl chloride quaternized product (trimethylammonioethyl acrylate chloride: 8 mol%) and acrylamide (92 mol%) (salt viscosity of 230 mPa · s, colloid equivalent) Value 1 meq./g)

  Cationic polymer (D1): Copolymer of dimethylaminoethyl acrylate methyl chloride quaternized product (trimethylammonioethyl acrylate chloride: 71 mol%) and acrylamide (29 mol%) (salt viscosity 2.8 mPa · s, Colloid equivalent value 4.5 meq./g)

<Examples 1-9>
Any of the cationic polymers (A1) to (A4), any of the cationic polymers (B1) to (B4), and a low molecular ammonium salt (T1; ammonium sulfate, Wako Pure Chemical Industries, Ltd., weight average particle diameter 1300 μm) Were uniformly mixed in the amounts used (parts by weight) shown in Table 1 to obtain the cationic polymer flocculants (1) to (9) of the present invention.

<Comparative Examples 1-5>
The cationic polymers (A1), (A2), (B1), (B3), (B4), (C1) or (D1) were uniformly mixed in the amounts used (parts by weight) listed in Table 1 for comparison. Cationic polymer flocculants (H1) to (H5) for use were obtained.

<Comparative Examples 6 to 10>
The cationic polymers (A1), (B1), (A2) or (B4) were used as cationic polymer flocculants (H6) to (H9) for comparison as they were, respectively.

<Concentration test>
Some cationic polymer flocculants obtained in Examples or Comparative Examples were each dissolved in tap water to prepare 0.2% aqueous solutions.
Excess sludge (pH 6.7, SS 0.8%) collected from a wastewater treatment plant in the Kansai region was placed in a 300 mL beaker, and the addition rate shown in Table 2 for the aqueous solution of the cationic polymer flocculant shown in Table 2 ( % / TS), and after stirring and mixing at 300 rpm for 20 seconds using a jar tester, the floc diameter (mm) was visually measured 30 seconds after the stirring was stopped, and for 3 minutes at room temperature. After being concentrated by standing at (about 25 ° C.) to obtain concentrated sludge, the solid content of the concentrated sludge was measured {measured similarly to the solid content (TS) of organic sludge. } This was defined as the sludge concentration (%). These results are shown in Table 2.

In the table, “coagulation failure” indicates that solid-liquid separation could not be performed.
Cationic polymer flocculants (1) to (5) and (8) (Examples 1 to 5 and 8) of the present invention are comparative polymer flocculants (H1) to (H3) and (H6) to ( Compared with H8) (Comparative Examples 1-3 and 6-8), excellent concentration efficiency was exhibited with a small addition rate.

<Dehydration test 1>
Some cationic polymer flocculants obtained in Examples or Comparative Examples were each dissolved in tap water to prepare 0.2% aqueous solutions.
Concentrated sludge (pH 7.4, TS2.5%) of K city sewage treatment plant was taken in a 300 mL beaker, and the aqueous solution of the cationic polymer flocculant shown in Table 3 was added as shown in Table 3 (% / TS). After stirring and mixing at 300 rpm for 20 seconds using a jar tester, the obtained floc is transferred to a nylon filter cloth (T-1189, diameter 9 cm) and naturally filtered, and remains on the filter cloth. The sludge was dehydrated with a small press for 1 minute to obtain a dehydrated cake. The solid content of this dehydrated cake was measured {measured in the same manner as the solid content (TS) of organic sludge. } From this value, the moisture content (%) of the dehydrated cake was calculated according to the following formula, and the results are shown in Table 2.
{Water content of dehydrated cake} = 100- {Solid content of dehydrated cake (TS,%)}

In the table, “poor dehydration” indicates that solid-liquid separation was not possible.
The cationic polymer flocculants (1), (3), (5) and (6) (Examples 1, 3, 5, 6) of the present invention are the polymer flocculants (H3) and (H4) for comparison. , (H6) and (H7) (Comparative Examples 3, 4, 6, and 7), it was possible to dehydrate with an excellent dehydration rate with a small addition rate.

<Dehydration test 2>
“Concentrated sludge from K city sewage treatment plant (pH 7.4, TS2.5%)” was changed to “Mix pig farm mixed sludge (pH 6.7, TS 3.5%, organic content 87%) in Kinki region” The dehydration test was conducted in the same manner as the dehydration test 1 except that the addition rate was set to “0.9% / TS” using the “cationic polymer flocculant (7)”. Was 82%.

  “Concentrated sludge from K city sewage treatment plant (pH 7.4, TS2.5%)” was changed to “Mix pig farm mixed sludge (pH 6.7, TS 3.5%, organic content 87%) in Kinki region” The comparative dehydration test was conducted in the same manner as the dehydration test 1 except that the comparative cationic polymer flocculant (H5) was used and the addition rate was set to “1.2% / TS”. The water content of the dehydrated cake was 84%.

  The cationic polymer flocculant (7) (Example 7) of the present invention was able to be dehydrated with an excellent dehydration rate with a small addition rate compared to the comparative polymer flocculant (H5) (Comparative Example 5). .

<Dehydration test 3>
"K city sewage treatment plant concentrated sludge (pH 7.4, TS2.5%)" is mixed with sludge, raw sludge and digested sludge (pH 7.6, TS 1.8 at O city sewage treatment plant in Kinki region). %, Organic content 80%) ”, using“ cationic polymer flocculant (8) ”and adding rate“ 1.8% / TS ”. As a result of the test, the moisture content of the dehydrated cake was 79.2%.

  "K city sewage treatment plant concentrated sludge (pH 7.4, TS2.5%)" is mixed with sludge, raw sludge and digested sludge (pH 7.6, TS 1.8 at O city sewage treatment plant in Kinki region). %, Organic content 80%) ”, using“ Comparative Cationic Polymer Flocculant (H9) ”and setting the addition rate to“ 1.9% / TS ”. When a dehydration test for comparison was performed, the water content of the dehydrated cake was 81%.

  The cationic polymer flocculant (8) (Example 8) of the present invention was able to be dehydrated with an excellent dehydration rate with a small addition rate compared to the comparative polymer flocculant (H9) (Comparative Example 9). .

<Dehydration test 4>
Changed the "K city sewage treatment plant concentrated sludge (pH 7.4, TS2.5%)" to "K city T sewage treatment plant mixed raw sludge (pH 5.8, TS 3%)" When the dehydration test was conducted in the same manner as the dehydration test 1 except that the polymer flocculant (9) was used and the addition rate was set to “0.5% / TS”, the moisture content of the dehydrated cake was 78. It was 9%.

  "K city sewage treatment plant concentrated sludge (pH 7.4, TS2.5%)" was changed to "K city T sewage treatment plant mixed raw sludge (pH 5.8, TS 3%)" When the dehydration test for comparison was conducted in the same manner as the dehydration test 1, except that the cationic polymer flocculant (H9) ”was used and the addition rate was set to“ 0.8% / TS ”, a dehydrated cake was obtained. The water content of was 81.2%.

  The cationic polymer flocculant (9) (Example 9) of the present invention was able to be dehydrated with an excellent dehydration rate with a smaller addition rate than the comparative polymer flocculant (H9) (Comparative Example 9). .

The cationic polymer flocculant of the present invention can be concentrated with excellent concentration efficiency and dehydrated with an excellent dewatering rate even with a small addition amount (addition rate) to organic sludge generated by treatment of sewage and the like. Therefore, it can be suitably used for concentration and dehydration of organic sludge. In particular, difficult-to-filter sludge can be concentrated and dehydrated efficiently, so that the moisture content of the dehydrated cake can be kept low. As a result, the fuel consumption required for incineration of the dehydrated cake can be reduced, resulting in a global warming that is a byproduct. The amount of generated gas can also be suppressed.
Therefore, in the present invention, the cationic polymer flocculant is suitable for organic sludge generated from microbial treatment such as sewage, human waste and / or industrial wastewater, and particularly suitable for concentration / dehydration of difficult-to-filter organic sludge. It is.

Claims (5)

A cationic polymer flocculant comprising a cationic polymer (A) having a salt viscosity of 130 to 210 mPa · s and a cationic polymer (B) having a salt viscosity of 5 to 60 mPa · s. The cationic polymer (A) is 1.2 to 4.8 meq. / G colloid equivalent value (CEa), and the cationic polymer (B) is 1.7 to 4.9 meq. 2. The cationic polymer flocculant according to claim 1, having a colloid equivalent value (CEb) of / g and a ratio of these colloid equivalent values (CEb / CEa) of 0.5 to 2. 3. The cationic polymer flocculant according to claim 1 or 2, further comprising a low molecular ammonium salt (T). A method for dewatering organic sludge, comprising adding the cationic polymer flocculant according to any one of claims 1 to 3 to the organic sludge for dehydration. A method for concentrating organic sludge, comprising adding and concentrating the cationic polymer flocculant according to any one of claims 1 to 3 to organic excess sludge or organic sludge containing the organic sludge.