JPH10500A - Sludge treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a process in which a large amount of sludge is dewatered efficiently in a unit time by a method in which after an inorganic coagulant being mixed into organic sludge, the aqueous solution of a sludge dewatering agent mixed with amphoteric polymer coagulants which are expressed by specified formulas is injected into a machine, and sludge is coagulated in a decanter. SOLUTION: After an inorganic coagulant being mixed into organic sludge, the aqueous solution of a sludge dewatering agent in which amphoteric polymer coagulants expressed by formulas I and II are mixed is injected into a machine, and sludge is coagulated in a decanter to be dewatered, In the formulas, R<1> is hydrogen or methyl group, R<2> is ethylene or propylene group, R<3> and R<4> reach methyl or ethyl group, R<5> is hydrogen, methyl, ethyl, or benzyl group, X<-> is counter anion; a+b+c=100 mole %, (a)=10-50 mole %, (b)=45-80 mole %, (c)=5-50 mole %, b+c+f = about 100 mole %, (d)=10-30 mole %, (e)=30-80 mole %, and (f)=10-40 mole %.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel sludge dewatering method, which uses a special type of polymer flocculant to perform high-efficiency dewatering and to produce a high-throughput dewatered cake with a small amount of addition. The purpose is to gain.

[0002]

2. Description of the Related Art A sludge dewatering method using various organic polymer flocculants has been proposed. JP-A-63-15
No. 8200 discloses that an amphoteric polymer flocculant having a ratio of cation equivalent value to anion equivalent value of 1.5 to 8.0 is added to an organic sludge having a pH value of 5 to 8 after addition of an inorganic flocculant. ,
Then, a method for dewatering sludge, which is characterized by dewatering, is described. JP-A-60-248299 discloses an organic sludge containing an acrylic acid hydrazide-based polymer compound and a polymer compound containing an amino group or a quaternary ammonium salt, and further containing an acid or acid salt, a neutral salt and A method for treating sludge, which comprises adding a solution containing at least one selected from alkalis and alkaline salts, is described. The high molecular compound containing an amino group or a quaternary ammonium salt mentioned herein is apparently a polymer containing no acrylic acid from the description of the detailed description of the invention in the specification. JP-A-61-216800 discloses that after adding a metal salt to organic sludge and stirring the mixture,
Furthermore, there is described a method for coagulating organic sludge, which comprises adding an acrylic acid hydrazide-based polymer compound and a cationic polymer compound containing an amino group or a quaternary ammonium salt to perform granulation. Further, Japanese Patent Application Laid-Open No. Sho 62-2
Japanese Patent No. 3500 discloses a sludge comprising adding a metal salt to a sludge, concentrating the sludge, and then adding an acrylic acid hydrazide-based polymer or an acrylic acid hydrazide-based polymer and a cationic polymer to the concentrated sludge for dehydration. A processing method is described.

[0003]

However, in the method of decanter dehydration, a method of efficiently dehydrating a large amount of sludge per unit time by consuming a small amount of polymer has not been known. An object of the present invention is to solve the above problems efficiently.

[0004]

Means for Solving the Problems In order to achieve the above object, the present invention is constituted as follows. The limitation of claim 1 is that after adding and mixing an inorganic flocculant to organic sludge, the amphoteric polymer flocculant (A) represented by the following formula (1) and the amphoteric polymer flocculant represented by the formula (2) ( This is a method for treating sludge, characterized by injecting an aqueous solution of a sludge dewatering agent obtained by mixing B) into an in-machine medicine, coagulating the sludge in a decanter, and dewatering the sludge. In-machine chemical injection refers to a chemical injection method in which a polymer flocculant aqueous solution and sludge are supplied from a rotating shaft portion into a decanter through a double pipe and mixed by rotation of a ball of the decanter.

Embedded image (Wherein R ¹ is a hydrogen atom or a methyl group, R ² is an ethylene group or a propylene group, R ³ and R ⁴ are a methyl group or an ethyl group, R ⁵ is a hydrogen atom _{, a} methyl group, an ethyl group or a benzyl group, X ⁻ Represents a counter anion, and a + b + c
= 100 mol%, a = 10 to 50 mol%, b = 45 to 8
5 mol%, c = 5 to 50 mol%. )

Embedded image (D + e + f = about 100 mol%, d = 10 to 30 mol%, e = 30 to 80 mol%, f = 10 to 40 mol%.) The limitation of claim 2 is the amphoteric polymer flocculant (A). ) And an amphoteric polymer flocculant (B) in a ratio of 6: 4 to 8: 2.
The limitation of claim 3 is that the inorganic coagulant is an iron salt and / or an aluminum salt.
The method for treating sludge according to the above. The limitation of claim 4 is the method for treating sludge according to claims 1 to 3, wherein the inorganic coagulant is polyaluminum chloride.
The limitation of claim 5 is the sludge treatment method according to claims 1 to 4, wherein the organic sludge is anaerobic digestion sludge of sewage.

Japanese Patent Application Laid-Open No. 60-248299 discloses an organic sludge containing an acrylic acid hydrazide-based polymer compound, a polymer compound containing an amino group or a quaternary ammonium salt, and an acid or acid salt, and a neutral salt. And a solution containing at least one selected from alkali and alkaline salts are described. The high molecular compound containing an amino group or a quaternary ammonium salt mentioned here avoids the production of acrylic acid in the description of the detailed description of the invention in the specification. It is clear that no system polymer flocculant is assumed. The composition of the acrylic acid hydrazide polymer compound described in the examples is a substance different from that of the present invention. That is, the acrylic acid hydrazide polymer compound of the present invention is a polymer having a crosslinked bond of several tens ppm to several hundred ppm obtained by reacting polyacrylamide with anhydrous hydrazine, and thus exhibits a special aggregation behavior. It exhibits a synergistic effect with the (meth) acrylate polymer flocculant and shows a strong flocculating effect. (D + e
The description of + f = about 100 mol% is due to the result of the presence of the above trace amount of cross-linking. ) Polymer mixing ratio is also
The range is different from that of the embodiment of 248299, and the evaluation method of the embodiment does not assume a decanter.
That is, it is difficult to make the invention of the present application based on Japanese Patent Application Laid-Open No. Sho 60-248299, and its inventive step and novelty are considered to be sufficiently worthy of a patent. As is apparent from the molecular formulas of the amphoteric polymers (A) and (B), it is obvious that the cationic groups of both polymers are dissociated and the anionic groups are not dissociated, and that they are in an acidic state. As the inorganic flocculant used in the present invention, polyaluminum chloride (PAC) or iron-containing PAC is preferably used. The organic sludge targeted by the present invention is particularly effective for anaerobic digested sludge of municipal sewage. Anaerobic digestion sludge from municipal sewage requires less fiber, more fine particles, higher alkalinity, poor dehydration, higher polymer coagulant addition, and lower decanter processing capacity than mixed raw sludge. I have no choice. The emergence of a high-polymer flocculant effective at a low addition amount for such anaerobic digested sludge is a breakthrough.

[0006]

EXAMPLES Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist.

The polymer coagulant (A) used in the present invention is obtained by dissolving a (meth) acrylate cationic monomer, acrylamide and acrylic acid in deionized water, and after deoxygenation, a water-soluble azo radical generator V manufactured by Wako Pure Chemical Industries, Ltd. Polymerization was carried out by adding -50, and the mixture was subjected to a test as a dilute aqueous solution having a polymer concentration of 0.2%. Hydrochloric acid of 5% with respect to the polymer was mixed for pH adjustment. The polymer flocculant (B) used in the present invention is a polymer containing a counter ion dissolved in a dilute hydrochloric acid aqueous solution after adding anhydrous hydrazine to a dry fine particle dispersion obtained by heating and dehydrating a reversed-phase emulsion polymer of polyacrylamide, and then dissolving in a dilute hydrochloric acid aqueous solution. It diluted so that it might become a 0.2% aqueous solution, and used for the test. The amounts of cations and anions were determined from the appropriate colloid values at PH3 and PH10 to determine the composition.
The intrinsic viscosities of the polymer flocculant (A) and the polymer flocculant (B) were determined by measuring the reduced viscosity with a Ostwald viscometer at 25 ° C. in 1N saline. Table 1 shows the characteristics of the polymer flocculant (A).

[Table 1] Similarly, the properties of the polymer flocculant (B) are shown in Table-2.

[Table 2] These were mixed to prepare a sample, which was subjected to an effect test.

[0008]

【The invention's effect】

Effect test-1 Anaerobic digestion sludge of municipal sewage sludge (SS: 9000 pp)
m, PH: 7.35), polyaluminum chloride was added and mixed with ₃ % of SS (alumina (Al ₂ O ₃ ) in terms of Al ₂ O ₃ ), and then a polymer flocculant was added and mixed by in-machine injection, followed by dehydration with a decanter. Table 3 shows the results of the dehydration test. The chemical injection amount is an amount that can obtain a recovery rate of 98% or more.

[Table 3] The effect of the present invention on reducing the amount of injected medicine is remarkable and is effective for cost reduction. Incidentally, an equivalent mixture of the Mannich-modified polyacrylamide and each of the examples of the polymer flocculant (B) equivalent to those described in the examples of JP-A-60-248299 did not achieve a recovery rate of 95% or more. Effect Test -2 effect test sludge on polyaluminum chloride used -1 alumina (Al ₂ O ₃₎ after adding and mixing a conversion pair SS3%, decanter after forming the floc was added and mixed polymeric flocculant flocculation tank , The recovery rate was 70% or less for each addition amount of the effect test-1. From this fact, it is understood that in-flight injection is an absolutely necessary condition for the addition of the polymer of the present invention.

Claims (5)

[Claims] An amphoteric polymer flocculant (A) represented by the following formula (1) and an amphoteric polymer flocculant (B) represented by the following formula (2) after adding and mixing an inorganic flocculant to the organic sludge. ), Wherein an aqueous solution of a sludge dewatering agent obtained by mixing the sludge is injected into the machine, the sludge is coagulated in a decanter, and the sludge is dewatered. Embedded image (Wherein R ¹ is a hydrogen atom or a methyl group, R ² is an ethylene group or a propylene group, R ³ and R ⁴ are a methyl group or an ethyl group, R ⁵ is a hydrogen atom _{, a} methyl group, an ethyl group or a benzyl group, X ⁻ Represents a counter anion, and a + b + c
= 100 mol%, a = 10 to 50 mol%, b = 45 to 8
5 mol%, c = 5 to 50 mol%. ) (D + e + f = about 100 mol%, d = 10 to 30 mol%, e = 30 to 80 mol%, and f = 10 to 40 mol%) 2. The method for treating sludge according to claim 1, wherein the amphoteric polymer flocculant (A) and the amphoteric polymer flocculant (B) are used together in a ratio of 6: 4 to 8: 2. . 3. The method for treating sludge according to claim 1, wherein the inorganic coagulant is an iron salt and / or an aluminum salt. 4. The method for treating sludge according to claim 1, wherein the inorganic flocculant is polyaluminum chloride. 5. The method for treating sludge according to claim 1, wherein the organic sludge is anaerobic digestion sludge of sewage.