JPH07178399A - Sludge dehydrating agent and treatment of sludge using the same - Google Patents

Abstract

PURPOSE:To obtain a sludge dehydrating agent capable of further reducing the water content of dehydrated cake of an organic sludge by combining acrylic acid hydrazide based polymer compound with an amidine based polymer compound. CONSTITUTION:The sludge dehydrating agent is obtained by combining the acrylic acid hydrazide based polymer compound (A) with the amidine based polymer compound (B). The compound (A) is expressed by a formula I [wherein R is H or CH3; A is a monomer unit of acrylamide, methacrylamide, acrylic ester or methacrylic ester; B is acrylic acid or its salt, methacrylic acid or its salt or a monomer unit copolymereizable with A, and (l)-(n) have relations of 0mol%<=1<=100mol% and n+m+l=100mol%]. And the compound (B) is expressed by a formula II [wherein X is amide group, nitryl group, amine hydrochloride or formamide group, and (a) and (b) have relations of 5<=a<=100 and 0<=b<=95].

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dehydration treating agent and a treatment method for activated sludge used for biochemical treatment of sewage, night soil, pulp wastewater, food wastewater and general industrial wastewater.

[0002]

2. Description of the Related Art Biochemical treatments such as the activated sludge method are widely used for treating organic wastewater such as sewage, night soil, pulp wastewater, food wastewater and general industrial wastewater. In this biochemical treatment, sludge handling, especially sludge sedimentation and dewatering properties become problems, and when the specific gravity of sludge decreases, sludge cannot be concentrated and sludge flows out from the surface layer of the sedimentation tank. Cause In addition, when the water content of the treated sludge increases, it becomes a problem in the sludge dewatering and sludge incineration.

In Japanese Examined Patent Publication No. 1-48839,
By using a combination of acrylic acid hydrazide polymer and a quaternized product of aminoalkyl (meth) acrylate, the sludge dewatering property is enhanced, the peelability from the filter cloth and the water content of the sludge-treated cake are improved.

[0004]

According to the method disclosed in the above publication, the water content of the dehydrated cake of sludge can be lowered to some extent, but the dehydrated cake can be easily handled and incinerated more efficiently. In order to do so, it is required to further reduce the water content of the dehydrated cake.

An object of the present invention is to provide a sludge dewatering agent which can further reduce the water content of a dehydrated cake of organic sludge and a treatment method using the same, in order to satisfy such conventional demands. It is in.

[0006]

The sludge dewatering agent of the present invention comprises:
It is characterized in that an acrylic acid hydrazide polymer compound (A) and an amidine polymer compound (B) are combined.

As the acrylic acid hydrazide polymer compound (hereinafter referred to as "AH polymer") used in the present invention, a compound represented by the following general formula (I) is preferably used.

[0008]

[Chemical 3]

(Wherein R represents H or CH ₃ , A represents a monomer unit of acrylamide, methacrylamide, acrylic acid ester, methacrylic acid ester, B represents acrylic acid or a salt thereof, methacrylic acid or a salt thereof. Or represents a monomer unit copolymerizable with the above A,
l, m and n are 0 mol% <1 ≦ 100 mol%, n + m
+ L = 100 mol%) As the B unit copolymerizable with the A unit in the compound represented by the general formula (I), vinyl chloride, vinyl acetate, butadiene, styrene, acrylonitrile and the like can be mentioned.

The AH polymer may be a homopolymer of acrylic acid hydrazide, or may be an A unit and / or a B polymer.
It may be a copolymer obtained by copolymerizing units. In this case, the form of the copolymer may be any of block type, alternating type and random type. The intrinsic viscosity of the AH polymer is [η] (30 ° C, 1N-NaNO ₃ )> 0.1.
It is preferably (dl / g). The AH polymer can be produced, for example, by the method described in JP-A-55-144004.

The amidine polymer compound (hereinafter referred to as "AM polymer") used in the present invention is preferably a compound represented by the following general formula (II).

[0012]

[Chemical 4]

(In the formula, X represents an amide group, a nitrile group, an amine hydrochloride, or a formamide group, and a and b are
The molecular weight of the AM polymer having a relationship of 5 ≦ a ≦ 100 and 0 ≦ b ≦ 95 is usually preferably 200,000 or more, more preferably 500,000 or more.

The amount of these polymers added depends on the SS of sludge.
0.3 to 5.0% by weight in total with respect to (floating suspension)
Is preferred. As a method for adding the AH polymer and the AM polymer, generally, they are used as a single liquid before the addition, but they may be dissolved in separate containers in advance and added at the same time when they are used.

When one of these polymers is used in a liquid form, it is preferable to add an acid or an acid salt to adjust the pH to 4 or less in order to prevent insolubilization due to an ionic bond between the polymers. Such acids or acid salts include
Examples thereof include hydrochloric acid, sulfuric acid, sulfamic acid, sodium hydrogensulfate and the like. The dissolved polymer may be added before the organic sludge is supplied to the stirring tank, or may be added directly into the stirring tank.

The sludge dewatering agent of the present invention is preferably combined with a polymer compound (C) containing an amino group or a quaternary ammonium salt. A polymer compound containing an amino group or a quaternary ammonium salt (hereinafter,
"DA polymer"), an aminoalkyl acrylate such as dimethylaminoethyl acrylate,
Examples thereof include aminoalkylmethacrylates such as dimethylaminoethylmethacrylate, aminoalkylacrylamides such as dimethylaminopropylacrylamide, aminoalkylmethacrylamides such as dimethylaminopropylmethacrylamide, and quaternized products thereof. These polymers may be copolymers with other monomers. Other monomers include acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, vinyl acetate, acrylic acid ester, methacrylic acid ester, acrylic acid, methacrylic acid, ethacrylic acid (α-ethylacrylic acid), and sodium of these. Examples thereof include salts, potassium salts, ammonium salts, vinyl sulfonic acid, vinyl methyl sulfonic acid and their sodium salts, potassium salts, ammonium salts and the like.

AH polymer (A) and AM polymer (B)
And the DA polymer (C) are used in a weight ratio of 0.
1 <A / A + B + C <0.9, 0.1 <B / A + B + C
<0.8, 0 ≦ C / A + B + C ≦ 0.5 is preferable.

Even when the DA polymer is used in combination, the total amount of the polymers (A), (B) and (C) added is 0.3 to 5.0% by weight based on the SS of the sludge. It is preferable. Also when the DA polymer is used, it may be used as a single liquid, or each polymer may be dissolved in a separate container in advance and added at the same time when it is used.

The sludge treatment method of the present invention is characterized by adding a metal salt to organic sludge and adding the sludge dehydrating agent of the present invention. The metal salt used in the sludge treatment method of the present invention is preferably an aluminum or iron salt. Specifically, aluminum chloride, polyaluminum chloride (PA
C), sulfuric acid band, ferrous sulfate, ferric sulfate, ferric chloride, ferrous chloride, polyiron sulfate and the like. The addition of these metal salts makes the sludge flocs more likely to settle.

The amount of these metal salts added is 1 to 50% by weight, preferably 3 to 30% by weight, based on the SS of sludge. These metal salts can be added before, at the same time as, or after the addition of the above-mentioned AH polymer, AM polymer and DA polymer, but are preferably added to the sludge before the addition of these polymers. In such a preferred embodiment, first, the metal salt is added to the sludge, and stirring is appropriately performed so that the metal salt is uniformly dispersed in the sludge. Next, the above polymers are added as the same solution or separately at the same time, and the mixture is appropriately stirred and then dehydrated. Dehydration can be performed by a known means such as a belt press, a centrifuge, a screw press and a filter press.

[0021]

According to the sludge treatment method of the present invention, the metal salt is added to the organic sludge, and the AH polymer and the AM polymer are added. Organic sludge generally has a negative charge, and metal ions of a metal salt having a positive charge are attached to such organic sludge to neutralize the charge of the organic sludge. AH
It is speculated that the polymer chelate with the metal ions thus attached to the organic sludge, and at the same time, the cation portion of the AM polymer is ionically bound to the anion portion of the AH polymer. It is considered that such a bond results in a huge molecule that is insoluble in water and does not have tackiness, and as a result, the water content of the dehydrated cake can be significantly reduced.

In the present invention, when the DA polymer is used in combination, the cation portion of the DA polymer is ionically bonded to the anion portion of the AH polymer, and it is considered that the molecule becomes a huge molecule.

[0023]

EXAMPLES The present invention will be specifically described below with reference to examples. Table 1 shows the composition components of the dehydrating agent used in Examples and Comparative Examples. The sludge used in Examples and Comparative Examples had a pH of 7.0, SS2.1%, and VSS / SS.
A mixed sludge having a property of 80.5% and containing excess sludge from a night soil treatment plant and coagulated sedimented sludge was used.

[0024]

[Table 1]

Examples 1 and 2 100 ml of sludge was placed in a beaker of 300 ml, and polyaluminum chloride (PAC) was added to the sludge at 3000 ppm.
In addition, the mixture was stirred by a stirrer at 250 rpm for 30 seconds.
Next, a 0.2 wt% aqueous solution of a dehydrating agent having the composition shown in Table 2 was added so as to obtain the polymer addition rate shown in Table 2, and the mixture was further stirred at 250 rpm for 30 seconds. After measuring the floc diameter, a cylinder having an inner diameter of 50 mm was placed in a Nutcheroth set with a 100-mesh nylon filter cloth, and the agglomerated sludge was poured into the cylinder, and the amount of the filtrate after 10 seconds was measured using a graduated cylinder.

Next, the coagulated sludge remaining on the filter cloth is put on a polyester filter cloth for a belt press, and 0.4 kgf / cm ²
Was squeezed for 2 minutes and the water content of the dehydrated cake was measured. Table 2 shows the measurement results of the floc diameter, the amount of filtrate, the water content of the dehydrated cake, and the water content per SS in the dehydrated cake. In Table 2, the value of the water content per SS in parentheses is a relative value when Comparative Example 1 is set to 100.

Comparative Example 1 Using the dehydrating agent having the composition shown in Table 2, sludge was filtered and evaluated in the same manner as in Examples 1 and 2. The results are shown in Table 2.

[0028]

[Table 2]

Examples 3 and 4 100 ml of sludge was placed in a 300 ml beaker, and polyaluminum chloride (PAC) was added to the sludge at 3000 ppm.
In addition, the mixture was stirred by a stirrer at 250 rpm for 30 seconds.
Next, a 0.2 wt% aqueous solution of a dehydrating agent having the composition shown in Table 3 was added so as to obtain the polymer addition rate shown in Table 3, and the mixture was further stirred at 2000 prm for 1 minute 30 seconds. After measuring the flock diameter, place a cylinder with an inner diameter of 50 mm on the Nutcheroth set with 100 mesh nylon filter cloth,
Aggregated sludge was poured into it, and the amount of filtrate after 10 seconds was measured using a graduated cylinder.

Next, the coagulated sludge remaining on the filter cloth was wrapped with gauze and dehydrated for 1 minute with a centrifugal dehydrator having a centrifugal force of 2000 G, and the water content of the dehydrated cake was measured. Table 3 shows the measurement results of the floc diameter, the amount of filtrate, the water content of the dehydrated cake, and the water content per SS in the dehydrated cake [(in parentheses are relative values when Comparative Example 2 is 100)].

Comparative Examples 2 to 5 Using the polymers shown in Table 3, sludge was filtered in the same manner as in Examples 3 and 4 above. The measurement results are shown in Table 3.

[0032]

[Table 3]

As is clear from the results of Tables 1 and 2,
According to the present invention, Examples 1 to 4 in which the AH polymer and the AM polymer were used in combination had a lower water content in the dehydrated cake than Comparative Example 1 and Comparative Example 2 in which the AM polymer was not used in combination. The water content is low. Therefore, according to the present invention, the water content of the dehydrated cake of organic sludge can be significantly reduced as compared with the conventional case.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiro Kobayashi 463 Kagasuno, Kawauchi Town, Tokushima City Otsuka Chemical Co., Ltd. Tokushima Plant

Claims (7)

[Claims] 1. A sludge dehydrating agent comprising a combination of (A) an acrylic acid hydrazide polymer compound and (B) an amidine polymer compound. 2. The sludge dewatering agent according to claim 1, wherein the acrylic acid hydrazide polymer compound (A) is a compound represented by the following general formula (I). [Chemical 1] (In the formula, R represents H or CH ₃ , A represents a monomer unit of acrylamide, methacrylamide, acrylic ester, or methacrylic ester, B represents acrylic acid or a salt thereof, methacrylic acid or a salt thereof, or Represents a monomer unit copolymerizable with A, l, m and n
Is 0 mol% <1 ≦ 100 mol%, n + m + l = 100
Have a relationship of mol%) 3. The sludge dehydrating agent according to claim 1, wherein the amidine-based polymer compound (B) is a compound represented by the following general formula (II). [Chemical 2] (In the formula, X represents an amide group, a nitrile group, an amine hydrochloride, or a formamide group, and a and b are 5 ≦ a ≦ 10.
0, 0 ≦ b ≦ 95) 4. The sludge dewatering agent according to claim 1, further comprising a polymer compound (C) containing an amino group or a quaternary ammonium salt. 5. The polymer compound containing an amino group or a quaternary ammonium salt is at least one selected from aminoalkyl acrylates, aminoalkyl methacrylates, aminoalkyl acrylamides, aminoalkyl methacrylamides and quaternized products thereof. The sludge dewatering agent according to claim 4, which is a compound of 6. The method according to claim 1, wherein a metal salt is added to the organic sludge.
6. A sludge treatment method, which comprises adding the sludge dehydrating agent according to any one of 5 above. 7. The sludge treatment method according to claim 6, wherein the metal salt is a salt of aluminum or iron.