JP2983279B2 - Composition for sludge dewatering agent - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a composition for a dehydrating agent that is effective for coagulation and dehydration of sludge generated by treatment of sewage treatment, human waste treatment, various industrial wastewaters, domestic wastewater, and the like.

[Prior art] Conventionally, sludge generated by treatment of various industrial wastewater, sewage, night soil, etc., after adding a cationic polymer compound,
It is treated after dehydration with a screw decanter, filter press, belt press, etc.

These sludges are mainly composed of organic matter, often of which is spoiled. For this reason, sludge generally has caking properties, hydrophilicity, and water absorbability, and in addition, has low strength and is bulky, so that it is not possible to mechanically dewater it for disposal as it is. This is one of the reasons why it is necessary to add a chemical for pretreatment for dehydration.

Dewatered sludge (hereinafter referred to as dewatered cake) is sometimes used for landfills, but is mostly incinerated. Most of the fuel used in incineration is used for evaporating water in dewatered sludge, but it is generally said that a 1% decrease in water in a dewatered cake can save about 10% of fuel. Therefore, there is a demand for reducing the water content of the dewatered cake in order to reduce fuel costs in incineration. This is also the reason for adding the drug, and the low water content of the cake is also a criterion for selecting the drug to be added.

To dewater such sludge, a polymer dehydrating agent containing a high molecular weight cationic polymer compound, particularly a quaternary ammonium salt or an acid salt of dimethylaminoethyl methacrylate, as a polymerization component has been widely used. Was.

By the way, especially for highly organic sludge, for example, sludge generated from a sewage treatment plant containing a large amount of domestic wastewater or sludge generated from a human waste treatment plant, the above-mentioned ordinary cationic polymer dehydrating agent is used. In many cases, a sufficient dewatering effect cannot be obtained. In such a case, not only does the water content of the dewatered cake not decrease, but also the strength of the dewatered floc is weak, and the recovery of suspended solids (hereinafter referred to as SS) Is also low.

For the dehydration of such sludge, a combination of a cationic polymer dehydrating agent obtained by modifying polyacrylamide with Mannich and an anionic polymer dehydrating agent (JP-A-58-139799), a conventional cationic polymer dehydrating agent And an anionic polymer dehydrating agent (Japanese Patent Application Laid-Open No. 58-215454).

However, such methods using a combination of a cationic polymer dehydrating agent and an anionic polymer dehydrating agent have improved the SS recovery rate, the water content of the dehydrated cake, and the peelability of the cake. In this case, the setting of the mixing ratio of each component and the complexity of the mixing operation remain as problems. Further, the Mannich-modified polymer does not have good storage stability, and an insoluble portion is formed even after storage for several months, so that the dehydration effect tends to decrease.

In order to solve such a problem, a dehydrating agent using an amphoteric polymer compound having both a cationic group and an anionic group, which is obtained by copolymerizing hydrochloric acid of dimethylaminopropylacrylamide with (meth) acrylic acid or a salt thereof. (JP-A-2-14799) has also been proposed, and as a result, an excellent sludge dewatering agent having storage stability, dewatering performance, and sludge treatment ability with high pH has appeared.

[Problems to be Solved by the Invention] However, unfortunately, even with this amphoteric polymer sludge dehydrating agent, the flocculated floc after addition has stickiness or breakage, and the floc size varies. It has also been found that sludge re-condensation may not be satisfactory as it is.

[Means for Solving the Problems] The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, by adding a certain amphoteric polymer compound to the cationic polymer compound, The present inventors have found that a composition for a dehydrating agent having improved coagulation dewatering performance and cohesive floc properties can be obtained, and based on this, the present invention has been completed.

That is, the present invention relates to a cationic polymer compound and at least one of cationic units represented by the following general formulas (I), (II), (II '), (III) and (III'). The present invention provides a composition for a sludge dewatering agent prepared by mixing an amphoteric polymer compound containing an anionic unit represented by the general formula (IV).

[However, the above formulas (I), (II), (II '), (II
In I), (III ′) and (IV), R ₁ and R ₂ are each independently a hydrogen atom, a methyl group or a cyclohexyl group, R ₃ is a hydrogen atom or a methyl group, and R is a hydrogen atom, methyl R ₅ and R ₆ are each independently a methyl group or a benzyl group; X is an anion (for example, an anion such as halogen or methyl sulfate); and Y is independent of each of the carboxyl groups to be bonded. Hydrogen, sodium, potassium or ammonium. The cationic polymer compound used in the composition for a sludge dewatering agent of the present invention is not particularly limited. Examples thereof include dialkylaminoalkyl acrylate, dialkylaminoalkyl methacrylate, dialkylaminoalkyl acrylamide or dialkylaminoalkyl methacrylamide. A quaternary or acid addition salt homopolymer, a copolymer of the above monomers with acrylamide or methacrylamide, a Mannich-modified or Hoffman-decomposed product of polyacrylamide, a homopolymer or copolymer of diallyldimethylammonium chloride, Vinylamine homopolymer or copolymer, vinylimidazoline homopolymer or copolymer, polyethyleneimine,
Epihalohydrin-amine condensates, dicyandiamide condensates, homopolymers of monoarylamine, homopolymers of diallylamine, homopolymers of N-alkyldiallylamine and the like are possible.

The molecular weight of these cationic polymers is 10,000-15,000
A range of 0,000 is preferred.

The above-mentioned cationic polymer compounds can be mixed in any kind and in any ratio as long as no adverse effects due to the interaction are observed.

Of these, particularly preferably used are quaternized products of dialkylaminoalkyl acrylate or dialkylaminoalkyl methacrylate or homopolymers of acid addition salts, copolymers of the above acrylate monomers with acrylamide or methacrylamide, dialkylamino A homopolymer of a quaternized product of an alkylacrylamide or a dialkylaminoalkylmethacrylamide or an acid addition salt, or a copolymer of a quaternized product of a dialkylaminoalkylacrylamide or a dialkylaminoalkylmethacrylamide or an acid addition salt with acrylamide or methacrylamide It is a polymer.

It is particularly preferred that the molecular weight is in the range from 1,000,000 to 15,000,000.

 Next, the amphoteric polymer compound will be described.

This amphoteric polymer compound has the general formula (I) or (I
It contains at least one of the cationic units represented by I), (II '), (III) and (III') and an anionic unit represented by the following general formula (IV). The compounds include the following.

These amphoteric polymer compounds (A), (B),
In (B ′), (C) and (C ′), the cationic unit and the anionic unit are bonded alternately or randomly.

The amphoteric polymer compound includes, as cationic monomers, for example, monoallylamine, N-methylallylamine, N, N-dimethylallylamine, N-cyclohexylallylamine, N, N- (methyl) cyclohexylallylamine, N, N-dicyclohexylallylamine , Diallylamine, N-methyldiallylamine, N-benzyldiallylamine, diallyldimethylammonium chloride, diallyldimethylammonium bromide, diallyldimethylammonium iodide, diallyldimethylammonium methylsulfate, diallylmethylbenzylammonium chloride, diallylmethylbenzylammonium bromide, iodine Diallyl methylbenzyl ammonium bromide, diallyl methyl benzyl ammonium methyl sulfate, diallyl dibenzyl ammonium chloride, diallyl dibromide Benzylammonium, diallyldibenzylammonium iodide, diallyldibenzylammonium methylsulfate, etc., and as anionic monomers, for example, maleic acid, citraconic acid or their sodium, potassium, ammonium salts, etc. It is obtained by copolymerization.

Monoallylamine, as the cationic monomer,
It is particularly preferable to use diallylamine, methyldiallylamine, diallyldimethylammonium chloride, and the like, and as the anionic monomer, maleic acid, citraconic acid, and the like.

The molar abundance ratio of the cationic unit and the anionic unit in the polymer after copolymerization is in the range of 5: 1 to 1: 3, preferably 3: 1 to 1: 2.

The molecular weight of the amphoteric polymer compound is preferably in the range of 1,000 to 10,000,000.

Specific examples of the amphoteric polymer compound include the following.

The amphoteric polymer compound represented by the general formula (A) includes monoallylamine, N-methylallylamine, N, N-dimethylallylamine, N-cyclohexylallylamine,
N- (methyl) cyclohexylallylamine or N, N-
And copolymers of dicyclohexylallylamine with maleic acid, citraconic acid or their sodium, potassium, and ammonium salts.

The amphoteric polymer compound represented by the general formula (B) or (B ') includes diallylamine, N-methyldiallylamine or N-benzyldiallylamine with maleic acid, citraconic acid or their sodium, potassium, and ammonium salts. And copolymers.

The amphoteric polymer compound represented by the general formula (C) or (C ′) includes diallyldimethylammonium chloride, diallyldimethylammonium bromide, diallyldimethylammonium iodide, diallyldimethylammonium methylsulfate, diallyldimethylbenzylammonium chloride, Diallyl methylbenzyl ammonium iodide, diallyl methyl benzyl ammonium iodide, diallyl methyl benzyl ammonium methyl sulfate, diallyl dibenzyl ammonium chloride, diallyl dibenzyl ammonium bromide, diallyl dibenzyl ammonium iodide or diallyl dibenzyl ammonium methyl sulfate and maleic acid, And citraconic acid or a copolymer thereof with a sodium salt, a potassium salt, or an ammonium salt.

The polymerization of these amphoteric polymer compounds is performed under the following conditions.

The cationic monomer and the anionic monomer are each mixed in water. The polymerization initiator is ammonium persulfate,
Peroxides such as potassium persulfate, hydrogen peroxide, tert-butyl hydroperoxide, or peroxides and Fe ⁺⁺ ,
A redox catalyst combining a reducing agent such as NaSO ₃ or ascorbic acid can be used. The polymerization reaction is carried out in N ₂ at atmospheric pressure. The polymerization temperature is 10 to 100 ° C, preferably 25 to 65 ° C, and the reaction time is 10 to 120 hours, usually 24 hours.
~ 96 hours. After completion of the reaction, the amphoteric polymer compound is obtained as an aqueous solution, which can be dried and pulverized to a powder if necessary.

Since this amphoteric polymer compound is chemically stable, if the cationic polymer compound is also chemically stable, the composition can be used as a dehydrating agent to remove sludge in a wide pH range and to control pH fluctuation. It can also be used when processing by a large method.

The composition for sludge dewatering agent is a cationic polymer compound,
It is obtained by adding the amphoteric polymer compound. It is a feature of the present invention that a small amount of an amphoteric polymer compound is added to the cationic polymer compound. The added amount of the amphoteric polymer compound is preferably 0.1 to 15% by weight of the whole. When the amphoteric polymer compound is less than 0.1% by weight of the entire polymer compound as a component, it becomes difficult to exhibit its properties. If it exceeds 15% by weight, the dewatering performance of the composition will gradually decrease, and the improvement of the properties of the dewatered cake will be smaller than the ratio of addition, and the addition efficiency will decrease.

 A particularly preferred addition amount is 1 to 10% by weight.

At the time of use, a composition for a sludge dehydrating agent composed of two kinds of polymer compounds is made into an aqueous solution of 0.01 to 1% by weight, and is added to sludge to be treated or suspended matter in wastewater to form flocs. This floc is usually dewatered by a mechanical method.

The amphoteric polymer compound is mixed with the cationic polymer compound in advance and used as a composition, and the final mixing ratio of the sludge after adding only the cationic polymer compound is preferably 0.1 to 15% by weight. It can also be used like adding.

[Action] Although it is not exactly clear why mixing the amphoteric polymer compound with the cationic polymer compound improves the sludge dewatering performance, it is speculated as follows. Cationic polymer compounds have hydrophilicity and sludge cohesion. Also,
The amphoteric polymer compound has a sterically stable structure due to the repulsion of both positive and negative ions in the molecule, and maintains good dewatering properties and filter cloth releasability even when it reacts with highly sticky sludge. There is a nature to do. It is considered that the excellent effects of the composition for a sludge dewatering agent of the present invention are exhibited by mutually complementing the functions of these polymer compounds.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

(Reference Example) amphoteric Synthesis of Polymer Compound (1) monoallylamine 107 g (1.874 mol) and 174g of maleic acid (1.899 mol) was dissolved in water 110g, 55 ° C. in N ₂ was added of ammonium persulfate 13 g, 96 h The polymerization reaction was performed. After terminating the reaction, the yield of the amphoteric polymer compound obtained by the methanol reprecipitation method was 88%. Using a 1/10 normal sodium chloride aqueous solution as a solvent, c = 0.5 g / dl, measured at 30 ° C. The intrinsic viscosity of this amphoteric polymer compound is 0.31 dl / g
Met. Hereinafter, the amphoteric polymer compound is referred to as an amphoteric polymer compound (a) (the amphoteric polymer compound (a) is included in the amphoteric polymer compound of the general formula (A)).

(2) Similarly, 97 g (0.998 mol) of diallylamine and 58 g (0.500 mol) of maleic acid were dissolved in 288 g of water, and 0.47 g of ammonium persulfate was added to carry out a polymerization reaction at 45 ° C. for 72 hours in N ₂ . The yield of the amphoteric polymer compound by the methanol reprecipitation method was 99.5%. The intrinsic viscosity of the amphoteric polymer compound was 1.48 dl / g, measured at 30 ° C. using c / 10.5 g / dl aqueous sodium hydroxide as a solvent. Hereinafter, the amphoteric polymer compound is referred to as an amphoteric polymer compound (b) (the amphoteric polymer compound (b) is included in the amphoteric polymer compound of the general formula (B) or (B ')).

(3) Similarly, 167 g (1.502 mol) of methyldiallylamine
And 130 g (0.999 mol) of citraconic acid dissolved in 445 g of water,
2.9 g of ammonium persulfate was added, and a polymerization reaction was performed at 55 ° C. for 48 hours in N ₂ . The yield of the amphoteric polymer compound by the methanol reprecipitation method was 76%. The intrinsic viscosity of this amphoteric polymer compound was 0.21 dl / g, measured at 30 ° C. using c / 10 gram aqueous sodium hydroxide as a solvent and c = 0.5 g / dl. Hereinafter, the amphoteric polymer compound is referred to as an amphoteric polymer compound (c) (the amphoteric polymer compound (c) is included in the amphoteric polymer compound of the general formula (B) or (B ')).

(4) Similarly, 176.6 g (1 mol) of diallyldimethylammonium chloride (purity: 91.2%) and 100 g (1 mol) of 40% NaOH were dissolved in 124.9 g of water, and 98.0 g of maleic anhydride was added thereto.
After adding and dissolving 6 g (1 mol), the system is kept at 60-65 ° C.
Ammonium persulfate (10.5 g, 3.5% by weight based on the monomer) was added in two portions, followed by polymerization for 72 hours. The yield of the amphoteric polymer compound by the methanol reprecipitation method was 98%. The intrinsic viscosity of the amphoteric polymer compound was 0.32 dl / g as measured at 30 ° C. using a 1/10 normal sodium chloride aqueous solution as a solvent and C = 0.5 g / dl. Hereinafter, the amphoteric polymer compound is referred to as an amphoteric polymer compound (d) (the amphoteric polymer compound (d) is included in the amphoteric polymer compound represented by the general formula (C) or (C ′)).

These amphoteric polymer compounds (a), (b), (c),
(D) Both used after drying and pulverizing into powder.

Synthesis of Chaotic Polymer Compound A cationic polymer compound was obtained by homopolymerizing methyl quaternary salt of N, N-dimethylaminoethyl methacrylate. The viscosity of the 1% aqueous solution was 4000 CPS.
Hereinafter, the present cationic polymer compound is referred to as a cationic polymer compound (a).

(Examples 1 to 16) Measurement of Coagulation Effect of Sludge Dewatering Agent Composition of the Present Invention The performance of the sludge dewatering agent composition of the present invention was measured by the following method and conditions.

The composition for a sludge dewatering agent was prepared by adding 5% of the cationic polymer compound (a) obtained in Reference Example to the amphoteric polymer compounds (A), (B), (C), and (D) obtained in Reference Example. , 10%. As shown in Table 1, these compositions were used as compositions (i), (ii), (iii), (iv),
(V), (vi), (vii), and (viii).

The evaluation of the dehydration effect was performed by the following Nutsche test. Take 200ml of sludge into a beaker and add 0.2% by weight
A predetermined amount of an aqueous solution containing the composition for a sludge dewatering agent is added and mixed well. Pour it over 100 mesh nylon filter cloth and add 3
The filtrate volume after 0 seconds was measured. The sludge floc on the filter cloth was applied with a load of 1 kg / cm ² for 1 minute using a compression tester to form a dewatered cake, and the water content of the cake and the releasability of the filter cloth were determined.

For the measurement, mixed sludge from a sewage treatment plant and mixed sludge from a human waste treatment plant were used as samples.

The mixed sludge of the sewage treatment plant has a pH of 6.0 and a SS of 2.6%, and contains the compositions (i), (ii), (iii), (iv), (v),
(Vi), (vii), and (viii) were added at 0.8% by weight based on SS. The results of the Nutsche test are shown in Table 1 (Examples 1 to 8).

The mixed sludge of the night soil treatment plant has a pH of 6.8 and a SS of 1.8%, and the composition (i), (ii), (iii), (iv), (v),
(Vi), (vii) and (viii) were added at 1.6% by weight based on SS. The results of the Nutsche test are shown in Table 2 (Examples 9 to 16).

(Comparative Examples 1 to 4) Measurement of Dehydration Effect of Conventional Polymer Dehydrating Agent Similarly, the dehydration performance was similarly measured using only the chaotic polymer compound (a) used in combination with the amphoteric polymer compound in Examples 1 to 16 above. Was measured (Comparative Examples 1 and 2).

Also, only the cationic polymer (b) (1% aqueous solution has a viscosity of 4000 CPS) obtained by polymerizing methyl quaternary salt of N, N-dimethylaminoethyl acrylate and acrylamide in a molar ratio of 80:20. Then, the dewatering performance was measured similarly (Comparative Examples 3 and 4).

The results are shown in Table 1 (Comparative Examples 1 and 2) and Table 2 (Comparative Examples 3 and 4).

(Comparative Examples 5 to 7) Measurement of agglomeration effect of composition for sludge dehydrating agent not included in the present invention 50:50 component weight composition of methyl quaternary salt of N, N-dimethylaminoethyl methacrylate and acrylic acid Amphoteric polymer compound (c) obtained by polymerization at a specific ratio (this amphoteric polymer compound is not included in the amphoteric polymer compound of the present invention, and a 1% aqueous solution has a viscosity of 1800 CPS); The dry powder of the compound (c) and the dry powder of the cationic polymer compound (a) are mixed in a weight ratio of 5:95 or 10: 9.
Examples 1 to 8 were prepared by mixing at a ratio of 0 to form an aqueous solution.
In addition, the same operation as in Comparative Examples 1 and 2 was performed, and the mixture was added to the mixed sludge in the sewage treatment plant to perform a Nutsche test.

 Table 3 shows the obtained results.

[Effects of the Invention] As can be seen from the above Examples and Comparative Examples, the dewatering performance of the composition for a sludge dewatering agent of the present invention is as follows: Furthermore, it is superior to a composition for a dehydrating agent obtained by adding an amphoteric polymer compound not included in the amphoteric polymer compound used in the present invention. In addition, since the strength of the dewatered cake is high, the stickiness and breakage of the cake are small, and the cake is excellent in peelability, so that post-treatment is easy.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-193308 (JP, A) JP-A-2-31899 (JP, A) JP-A 64-4207 (JP, A) JP-A 61-1986 245806 (JP, A) JP-A-52-95584 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C02F 11/00-11/20 B01D 21/01

Claims (2)

(57) [Claims] 1. A cationic polymer compound and at least one of cationic units represented by the following general formulas (I), (II), (II '), (III) and (III'):
A composition for a sludge dewatering agent prepared by mixing a seed with an amphoteric polymer compound containing an anionic unit represented by the following general formula (IV). [However, the above formulas (I), (II), (II '), (II
In I), (III ′) and (IV), R ₁ and R ₂ are each independently a hydrogen atom, a methyl group or a cyclohexyl group, R ₃ is a hydrogen atom or a methyl group, and R is a hydrogen atom, methyl R ₅ and R ₆ are each independently a methyl group or a benzyl group, X is an anion, and Y is independently hydrogen, sodium, potassium or ammonium for each carboxyl group to be bonded. . ] 2. The sludge dewatering agent according to claim 1, wherein the amphoteric polymer compound is selected from the following compounds (A), (B), (B '), (C) and (C'). Composition. [However, in the above formulas (A), (B), (B '), (C) and (C'), R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , X and Y are Has the same meaning as defined in claim 1. ]