JP2010000425A - Sludge dewatering agent composition and sludge dewatering method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sludge dewatering agent composition and a sludge dewatering method which generate solid and drainable flocs, such as flocs generated by the single use of a crosslinked polymer, in various sludges to be dewatered to enable improvement of the amount of treated sludge and reduction of a cake moisture content, and can exhibit the effect with a very small addition amount of the dewatering agent in comparison with the single addition of the cross-linked polymer. <P>SOLUTION: A flocculate generated by mixing and agitating the sludge to be dewatered with the sludge dewatering agent composition combining (A) a crosslinking ionic water-soluble polymer having a charge inclusion ratio of 35% and more and 90% or less, and (B) an ionic water-soluble polymer having a charge inclusion ratio of 3% and more and 15% or less is dehydrated by a dehydrator. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a sludge dewatering agent composition and a sludge dewatering method.

The cross-linkable polymer capable of producing large and strong flocs, which is required for dehydrators that can obtain cakes with low water content such as screw press type dehydrators, which are increasing this year, has excellent cohesiveness and On the other hand, while exhibiting excellent effects such as a reduction in the moisture content of the cake, a large amount of addition is required to exhibit the effects, resulting in an increase in cost.

As a method of preventing this increase in the amount added, a method of using an inorganic flocculant in combination in the previous stage is known, but when composting a dehydrated cake, in order to avoid adverse effects on vegetation due to heavy metals in the cake, A dehydration method using only an organic flocculant without using an inorganic flocculant as much as possible has been increasingly desired.

Also mixed with sludge is a polymer flocculant that combines a vinyl polymerized crosslinkable water-soluble ionic polymer with a charge encapsulation rate of 35% or more and a vinyl polymerized crosslinkable water soluble polymer with a charge encapsulation rate of 5% or more and less than 35%. There are also known formulations for dehydration (Patent Document 1), but the number of dewatering sludge is increasing, and the number of dehydrators capable of obtaining cakes with low water content such as screw press dehydrators is increasing. However, even in this prescription, a satisfactory dehydration result is not always obtained.
JP 2005-144346 A

The present invention relates to a dehydration method. In order to produce strong and large aggregated floc, which is an excellent performance of the crosslinked polymer, the necessary addition amount can be reduced without reducing the performance of the crosslinked polymer that requires a large amount of addition. The present invention relates to a sludge dewatering agent composition and a sludge dewatering method.

This year, the number of dewatering machines that require strong coagulation flocs, such as screw presses, rotary presses, and multiple disk type dewatering machines, has increased, while the percentage of hard-water dewatering sludge increases in dewatering sludge dewatered by these dewatering machines. Therefore, there is a tendency that a crosslinkable polymer is often used as a suitable dehydrating polymer.

However, since a cross-linkable polymer has a large amount of addition necessary to exhibit an excellent effect, an increase in cost has been a problem.

The present invention makes it possible to significantly reduce the amount of addition required for exhibiting the excellent aggregation and dehydration effects of these crosslinkable polymers while maintaining the excellent aggregation and dehydration effects of the crosslinkable polymers. An object is to provide a sludge dewatering agent.

As a result of intensive studies to solve the above problems, the present inventors have found that the monomer represented by the following general formula (1) and / or (2) according to claim 1 has the following general formula (3) A cationic or amphoteric crosslinkable water-soluble polymer having a charge inclusion ratio of 35% or more and 90% or less obtained by polymerizing a mixture of a monomer represented by formula (I), a water-soluble nonionic monomer, and a crosslinkable monomer. Mixture of molecule (A), monomer represented by the following general formula (1) and / or (2), monomer represented by the following general formula (3), water-soluble nonionic monomer A sludge dehydrating agent composition obtained by mixing a cationic or amphoteric water-soluble polymer (B) having a charge inclusion rate of 3% or more and 15% or less obtained by polymerizing the slag into a sludge. The crosslinkable ionic water-soluble composition according to claim 1, wherein the sludge dewatering agent composition is added to the sludge and stirred. Excellent cohesive molecules (A), and while maintaining the water content reducing ability was found that the required amount can be greatly reduced.
General formula (1)
R ₁ is hydrogen or a methyl group, R ₂ and R ₃ are an alkyl group having 1 to ₃ carbon atoms, an alkoxyl group or a benzyl group, and R ₄ is hydrogen, an alkyl group having 1 to 3 carbon atoms, an alkoxyl group or a benzyl group. , Same or different. A is O or NH, B is an alkylene group or an alkoxylene group having 2 to 4 carbon atoms, _{X 1} ^- represents respectively an anion.
General formula (2)
R ₅ and R ₆ represent hydrogen or a methyl group, R ₇ represents an alkyl group having 1 to 3 carbon atoms, an alkoxy group or a benzyl group, and X ₂ ⁻ represents an anion.

General formula (3)
R ₈ is hydrogen, methyl group or CH ₂ COOY ₂ , Q is SO ₃ , C ₆ H ₄ SO ₃ ,
CONHC (CH ₃ ) ₂ CH ₂ SO ₃ , C ₆ H ₄ COO or COO,
R ₉ is hydrogen or COOY ₁ and Y ₁ is hydrogen or a cation.

The sludge dewatering agent composition in which the cationic or amphoteric crosslinkable water-soluble polymer (A) and the cationic or amphoteric water-soluble polymer (B) are mixed in a certain ratio is a cationic or amphoteric crosslinkable water-soluble polymer. While sludge dewatering with polymer (A) alone requires a large amount of addition to demonstrate its excellent cohesiveness and ability to reduce moisture content, while maintaining the same coagulation and dewatering performance The required amount of addition can be greatly reduced.

Cationic or amphoteric crosslinking, which can conventionally generate large flocs that are strong and have good drainage, by adding the sludge dehydrating agent composition according to claims 1 to 4 of the present invention to sludge and stirring to dehydrate. Since the amount of water-soluble polymer added can be greatly reduced, the processing cost can be greatly reduced.

In the present invention, the charge inclusion rate is defined as an index representing the degree of crosslinking of the crosslinkable water-soluble ionic polymer. That is, in the case of a cationic crosslinkable water-soluble ionic polymer and a crosslinkable water-soluble ionic polymer that is amphoteric and has a positive difference in molar concentration between a cationic monomer and an anionic monomer, Is calculated as follows.
Charge inclusion rate [%] = (1−α / β) × 100
α is a 0.01% aqueous solution of a crosslinkable water-soluble ionic polymer adjusted to pH 4.0 with acetic acid, and a PCD titrator (Muetek PCD 03, Mutek PCD-Two) manufactured by Mutek.
Titration by titrator version 2) was carried out by titrating with a drop solution: 1 / 1000N aqueous polyvinyl sulfonate solution, drop rate: 0.05 ml / 10 sec, end point determination: 0 mV. β is 1 / 400N in a 0.01% aqueous solution of a crosslinkable water-soluble ionic polymer adjusted to pH 4.0 with acetic acid.
A sufficient amount of potassium polyvinyl sulfonate aqueous solution was added to neutralize the charge, and the mixture was sufficiently stirred. Similarly, using a PCD titrator, dropping solution: 1/1000 N diallyldimethylammonium chloride aqueous solution, dropping rate: 0.05 ml / 10 sec End point determination: Titration is performed at 0 mv, and this titration value is subtracted from the blank value. A 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.
This is the titration amount obtained by titration with diallyldimethylammonium chloride aqueous solution, dropping rate: 0.05 ml / 10 sec, end point determination: 0 mV.

In the present invention, in a crosslinkable water-soluble ionic polymer that is amphoteric and has a negative difference in molar concentration between a cationic monomer and an anionic monomer, the charge inclusion rate is calculated as follows.
Charge inclusion rate [%] = (1−α / β) × 100
α is a 0.01% aqueous solution of a crosslinkable water-soluble ionic polymer adjusted to pH 10.0 with ammonia.
The titration volume was determined by titration with PCD 03, Muetek PCD-Two Titortor Version 2) by titrating with a dropping solution: 1 / 1000N diallyldimethylammonium chloride aqueous solution, dropping rate: 0.05 ml / 10 sec, end point determination: 0 mv. β is 1 / 400N in 0.01% aqueous solution of a crosslinkable water-soluble ionic polymer adjusted to pH 10.0 with ammonia.
Add sufficient amount of diallyldimethylammonium chloride aqueous solution to neutralize the charge, stir well, and similarly, using PCD titrator, drop solution: 1 / 1000N potassium polyvinylsulfonate aqueous solution, drop rate: 0.05 ml / 10 sec End point determination: Titration is performed at 0 mv, and this titration value is subtracted from the blank value. The blank value is an aqueous diallyldimethylammonium chloride solution having the same concentration as that of the above sample adjusted to pH 10.0 with ammonia.
A titration amount obtained by titrating at a polyvinyl polyvinyl sulfonate aqueous solution, dropping speed: 0.05 ml / 10 sec, end point determination: 0 mV.

The cationic or amphoteric crosslinkable water-soluble polymer (A) used in the present invention may be in any form of powder, emulsion and dispersion, but those having a charge inclusion rate of 35 to 90% are suitable.

The reason is that the polymer is effective for flocculation of hardly dewatering sludge and is particularly effective when using a dehydrator that requires a strong flocculating floc such as a screw press. Because it is.

The cationic or amphoteric water-soluble polymer (B) used in the present invention may be in the form of powder, emulsion, or dispersion, but has a charge inclusion rate of 3% to 15% and a molecular weight of 800. Ones more than 10,000 and less than 20 million are suitable.

For this reason, it is most desirable to use a cationic or amphoteric water-soluble polymer (B) having a molecular weight of a certain amount or more when mixed with a cationic or amphoteric crosslinkable water-soluble polymer (A). By mixing this with various types of sludge and mixing with a cationic or amphoteric crosslinkable water-soluble polymer (A) at a certain ratio, the cationic or amphoteric crosslinkable water-soluble polymer (A) can be used alone. Compared with the data of various sludge tests, it is confirmed that the required addition amount can be greatly reduced.

However, when the molecular weight is lower than 8 million, when mixed with a cationic or amphoteric crosslinkable water-soluble polymer (A), the amount of chemical addition, which is a major feature in the effect of the present invention, cannot be significantly reduced. It has been confirmed.

The mixing ratio of the cationic or amphoteric crosslinkable water-soluble polymer (A) and the cationic or amphoteric water-soluble polymer (B) to be mixed when preparing the sludge dehydrating agent composition used in the present invention is as follows. 50:50 to 95: 5 are preferred, and when the ratio of the cationic or amphoteric water-soluble polymer (B) is larger than that of the cationic or amphoteric water-soluble polymer (A), the crosslinkable water-soluble polymer. There is a strong tendency for the ability to form strong flocs to decrease.

The mixing ratio of the cationic or amphoteric crosslinkable water-soluble polymer (A) and the cationic or amphoteric water-soluble polymer (B) mixed when preparing the sludge dehydrating agent composition used in the present invention is By arbitrarily changing in the above-mentioned range depending on the sludge species, the dehydration effect can be exerted in the best form. That is, for the hardly dewatering sludge having a small fiber content, the cationic or amphoteric crosslinkable water-soluble polymer (A): cationic or amphoteric water-soluble polymer (B) is 80:20 to 95: 5. In the case of sludge having a high fiber content and easily dewatering, such as paper sludge sludge, the dehydration effect of 50:50 to 70:30 is particularly excellent. That is, by changing the mixing ratio of the sludge dehydrating agent composition used in the present invention arbitrarily depending on the type of sludge, the strong flock-forming ability of the crosslinkable ionic polymer is maintained for various types of sludge. However, the amount added can be greatly reduced.

The sludge dehydrating agent composition used in the present invention is capable of improving the treatment amount and reducing the moisture content of the dehydrated cake in various dehydrators at a chemical addition amount significantly lower than the required addition amount in the single formulation of the crosslinkable ionic polymer. However, it exhibits excellent dewatering effect particularly in screw presses, multiple disk dehydrators and rotary presses. Also in belt presses and centrifugal dehydrators, the effect of increasing the amount of treatment with a small amount of chemical addition and reducing the moisture content of the dehydrated cake are high.

The sludge dewatering agent composition used in the present invention is suitable for various types of sludge such as sewage mixed raw sludge, sewage surplus sludge, sewage digested sludge, human waste surplus sludge, chemical (food) surplus sludge, and various coagulated sediment sludge. However, as described above, by arbitrarily changing the mixing ratio of the cationic or amphoteric crosslinkable water-soluble polymer (A) and the cationic or amphoteric water-soluble polymer (B) depending on the type of sludge, It is possible to form a strong floc with an addition amount smaller than that of a commonly used crosslinkable ionic polymer.

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

(Adjustment of sludge dehydrating agent composition)
Table 1 shows ionic polymers that are sludge dehydrating agents used in the laboratory tests in the present invention.

(Table 1)
CB: Crosslinkable cationic water-soluble polymer CBX: Crosslinkable amphoteric water-soluble polymer C: Cationic water-soluble polymer, CX: Amphoteric water-soluble polymer AAm: Acrylamide, AAc: Acrylic acid DAA: Trimethylethyl acrylate ammonium chloride Lid DAM: Trimethylethyl methacrylate ammonium chloride 0.5% Salt viscosity: Viscosity measured at 25 ° C. with a B-type viscometer after complete dissolution of 0.5% in a 4% by weight salt aqueous solution

For the excess sludge (sludge properties are pH 6.8, SS: 8750, TS: 9000) generated from the sewage treatment plant (oxidation ditch method), a coagulation filtration test and a squeeze test were conducted for a screw press. The properties of this dewatering sludge are 200mesh-on residue 1.7% by weight / SS, the organic component is 87.8% by weight with respect to SS, the proportion of organic component is large, and the sludge particles are also small dewatering sludge Met. After adding 200 ml of sludge to a 300 ml polypropylene beaker, a 9: 1 mixture (BC-1) solution of CB1 and C1 (BC-1) was added, and the sludge was aggregated by transferring the beaker and stirring 20 times. Then, after observing the size of the floc, the filtration rate was examined with a 40 mesh beaker with a filter cloth. Further, the water content of the dehydrated cake was determined after press-dehydrating the aggregate after filtration for 60 seconds at a pressing pressure of 1.5 kgf / cm ² .

As a result, a moisture content of 79.3% by weight was obtained under the condition of an addition rate of 0.94% / SS. In addition, when a solution of 9: 1 mixture of CB5 and C1 (BC-3) was added and the same stirring, filtration, and dehydration tests were performed, the best floc formation, filtration rate, and cake water content were obtained in this experiment. The cake moisture content was 78.9 wt% at 0.94% / SS. These results are shown in Table 2.

(Comparative Test 1) A dewatering test was carried out on the sludge dewatering agents CB1, C2, CB2 and C1 each consisting of a single material. These results are shown in Table 3.

(Table 2) Example 1

(Table 3) Comparative test 1

Coagulation filtration test and squeeze test for centrifugal dehydrator for surplus sludge generated from human waste treatment plant (sludge properties are pH 6.5, SS: 14500 mg / 1, TS: 16500 mg / 1, VSS: 74.3%) Carried out. After adding 200 ml of sludge to a 300 ml polypropylene beaker, add a solution of 9: 1 (BC-3) mixture of CB5 and CX1 and agitate the sludge by stirring at 1000 rpm for 30 seconds with a stir bar. After observing the size, the filtration rate was examined with a 40 mesh beaker equipped with a filter cloth.

As a result, a large and good floc was obtained and a very high filtration rate was obtained. Further, the water content of the dehydrated cake was determined after press dewatering the aggregate after filtration for 30 seconds at a pressing pressure of 1.0 kgf / cm ² , and the water content was 82.4% by weight under the condition of 0.83% / SS addition rate. The rate was obtained. Further, when a solution of a mixture of CB3 and C1 (BC-2) (BC-2) was added and the same aggregation and dehydration tests were performed, the same good floc formation and filtration rate were obtained, and the cake moisture content was 0. A value of 82.2% by weight was obtained at 97% / SS. In addition, the best floc formation and filtration rate were obtained in this example in the case of an 8: 2 mixture of CB1 and C1 (BC-1), and the cake moisture content was 0.97% / SS at 82.1% by weight. The value of was obtained.

(Comparative test 2) The sludge dewatering test was implemented about the sludge dewatering agent CB2, C1, CB3, and C2 which consist of only. These results are shown in Table 5.

(Table 4) Example 2

(Table 5) Comparative Example 2

Coagulation filtration test for screw press on mixed sludge (sludge properties: pH 6.6, SS: 37500 mg / 1, TS: 39250 mg / 1, VSS: 57.4%) of paper sludge and excess sludge generated by a paper manufacturer And a squeeze test was conducted. Add 200 ml of sludge to a 300 ml polypropylene beaker, then add a 5: 5 mixture of CB4 and C4 (BC-1), stir 50 times with a spatula, transfer to the beaker and reciprocate 3 times. After the flocs were agglomerated and the size of the floc was observed, the filtration rate was examined using a beaker with a 40 mesh filter cloth.

As a result, the largest and good floc was obtained and a very fast filtration rate was obtained. Further, when the cake moisture content of the dehydrated cake was examined after press-dehydrating the aggregate after filtration for 60 seconds at a pressing pressure of 1.5 kgf / cm ² , the moisture content was 64.0% by weight at an addition rate of 0.32% / SS. was gotten. Further, when a solution of CB4 and a 7: 3 mixture of C4 (BC-2) was added and the same agglomeration and dehydration tests were performed, good floc formation and filtration rate were obtained, and the cake moisture content was 0.32. A value of 63.9% was obtained at an addition rate of% / SS. A 6: 4 mixture of CBX1 and C4 (BC-3) was added, and the same flocculation and dehydration were performed. As a result, the best floc formation and filtration rate were obtained in this example, and the moisture content of the cake was Thus, 63.2% was obtained at 0.32% / SS. These results are shown in Table 6.

(Comparative test 3) The sludge dewatering test was implemented about the sludge dehydrating agent CB4, C4, CB5, and CBX1 which consist of only. These results are shown in Table 7.

Table 6 Example 3

(Table 7) Comparative test 3

The sludge dewatering agent composition and the sludge dewatering method of the present invention can generate a strong and well-drained floc when dewatering sludge for dewatering generated from sewage treatment plants, human waste treatment plants, and factories with a dehydrator. In addition, since the required amount can be greatly reduced compared to the conventional formulations of crosslinkable ionic polymers, it is possible to greatly reduce chemical costs, and various sludges and a wide range Since it can cope with the dehydrator by changing its mixed species and mixing ratio, the industrial utility value is very high.

Claims (6)

A monomer represented by the following general formula (1) and / or (2) A mixture of a monomer represented by the following general formula (3), a water-soluble nonionic monomer, and a crosslinkable monomer A cationic or amphoteric crosslinkable water-soluble polymer (A) having a charge encapsulation rate of 35% or more and 90% or less obtained by polymerization, a monomer represented by the following general formula (1) and / or (2), Cationic or amphoteric water-soluble polymer (B) having a charge encapsulation rate of 3% to 15% obtained by polymerizing a mixture of a monomer represented by the following general formula (3) and a water-soluble nonionic monomer Sludge dehydrating agent composition.
General formula (1)
R ₁ is hydrogen or a methyl group, R ₂ and R ₃ are an alkyl group having 1 to ₃ carbon atoms, an alkoxyl group or a benzyl group, and R ₄ is hydrogen, an alkyl group having 1 to 3 carbon atoms, an alkoxyl group or a benzyl group. , Same or different. A is O or NH, B is an alkylene group or an alkoxylene group having 2 to 4 carbon atoms, _{X 1} ^- represents respectively an anion.
General formula (2)
R ₅ and R ₆ represent hydrogen or a methyl group, R ₇ represents an alkyl group having 1 to 3 carbon atoms, an alkoxy group or a benzyl group, and X ₂ ⁻ represents an anion.
General formula (3)
R ₈ is hydrogen, methyl group or CH ₂ COOY ₂ , Q is SO ₃ , C ₆ H ₄ SO ₃ ,
CONHC (CH ₃ ) ₂ CH ₂ SO ₃ , C ₆ H ₄ COO or COO,
R ₉ is hydrogen or COOY ₁ and Y ₁ is hydrogen or a cation. 2. The sludge dewatering agent composition according to claim 1, wherein the proportion of the cationic structural unit of the cationic or amphoteric crosslinkable water-soluble polymer (A) is 10 mol% to 100 mol%. The sludge dewatering agent composition according to claim 1, wherein the proportion of the cationic structural unit of the cationic or amphoteric water-soluble polymer (B) is 20 to 100 mol%. The sludge dehydrating agent composition according to any one of claims 1 to 3, wherein the cationic or amphoteric water-soluble polymer (B) has a weight average molecular weight of 8 to 20 million. The mixing ratio of the cationic or amphoteric crosslinkable water-soluble polymer (A) and the cationic or amphoteric water-soluble polymer (B) is 50:50 to 95: 5. The sludge dehydrating agent composition described. A sludge dewatering method comprising: adding and stirring the sludge dewatering agent composition according to claim 1 to sludge, and then dewatering with a dehydrator.