JPH03293100A - Sludge dehydrating agent - Google Patents

Abstract

PURPOSE:To obtain the sludge dehydrating agent which is excellent in flocculation and dehydration performance, is less thermally deteriorated and deteriorated with lapse of time and is highly stable by incorporating a specific cationic constituting unit at a specific ratio further into an amphoteric polymer contg. a specific cationic constituting unit, anionic constituting unit and noninoic constituting unit. CONSTITUTION:The cationic constituting unit expressed by formula II (R4 and R5 are respectively 1 to 4 alkyl groups which may be the same as or different from each other; R6 is a hydrogen atom, 1 to 4C alkyl group or benzyl group) X2(-) is anion) is incorporated at 1 to 5mol% into the amphoteric polymer contg. the cationic constituting unit, anionic constituting unit and noninoic constituting unit expressed by formula l (R1 and R2 are respectively 1 to 4C alkyl groups which may be the same as or different from each other; R3 is a hydrogen atom, 1 to 4C alkyl group or benzyl group; X1(-) is anion).

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a novel sludge dewatering agent, more specifically, it has excellent flocculation and dewatering performance, can obtain dehydrated sludge with a low water content, and is resistant to thermal deterioration. The present invention relates to a sludge dewatering agent containing an amphoteric polymer as an active ingredient, which exhibits excellent stability and little deterioration over time.

[Conventional technology] Conventionally, sewage treatment, human waste treatment, organic degree! Cationic polymer dehydrating agents were used alone to dehydrate organic sludge generated from wastewater treatment, etc. However, in recent years, due to an increase in the amount of sludge generated and deterioration of sludge properties, conventional cationic polymer dehydrating agents have been used. When using a dehydrating agent, there is a limit to the amount of sludge that can be buried, and the water content of the dehydrated cake, the recovery rate of SS, and the removability of the cake from the filter cloth are not always satisfactory. It was wanted.

Therefore, several proposals have been made so far to improve the drawbacks of such cationic polymer dehydrating agents. For example, (1) a copolymer comprising a tertiary or quaternary nitrogen-containing (meth)acrylate and a tertiary or quaternary nitrogen-containing (meth)acrylamide as essential components (JP-A No. 58-49410) (2) A method of using a cationic polymer dehydrating agent and an anionic polymer dehydrating agent together (Japanese Unexamined Patent Publication No. 129200/1983), (3) A method of using a cationic polymer dehydrating agent and an anionic polymer dehydrating agent together (JP-A-62-129200); Ampholytic polymer dehydrating agent containing anionic structural unit
149292, 62-205112), etc. have been proposed.

However, although the above copolymer (1) may be slightly improved in terms of SS recovery rate and cake removability from the filter cloth compared to conventional cationic polymer dehydrating agents, it has poor performance. (2)
), in which a cationic polymer dehydrating agent and an anionic polymer dehydrating agent are used together, the recovery rate of SS, the moisture content of the cake, and the releasability from the filter cloth are improved to some extent, but the mixing of each component is Setting ratios, mixing operations, etc. are complicated, and there are many problems in terms of handling, such as the possibility that undissolved substances may be generated depending on the pH of the dissolved water during dissolution.

Furthermore, the amphoteric polymer dehydrating properties (3) above have better cohesiveness and superior performance in terms of SS recovery rate and cake moisture content compared to conventional cationic polymer dehydrating agents. However, the stability is extremely poor, for example: (1) thermal deterioration during the heat drying process during polymer powder production is significant, and insoluble gel is likely to form when dissolved in water; (2) stability of powdered polymer over time; (3) Polymer aqueous solutions have poor stability over time, resulting in a decrease in viscosity and, in some cases, precipitation. This has the drawback that it can lead to undesirable situations such as serious troubles in the field where it is used.

[Problems to be Solved by the Invention] The present invention overcomes the drawbacks of conventional amphoteric polymer dehydrating agents, has excellent flocculation and dewatering performance, can obtain sludge with a low water content, and This invention was developed for the purpose of providing a sludge dewatering agent containing an amphoteric polymer as an active ingredient, which exhibits excellent stability with little deterioration or deterioration over time.

[Means for Solving the Problems] As a result of intensive research to develop the above-mentioned preferable sludge dewatering agent, the present inventors found that a specific cationic structural unit and
An amphoteric polymer containing anionic structural units and nonionic 111IFf: units can further contain specific cationic structural units in a predetermined ratio to achieve its purpose. The inventors have discovered what can be achieved, and have completed the present invention based on this knowledge.

That is, the present invention is based on (A) the general formula % formula % () (R and R1 in the formula are each an alkyl group having 1 to 4 carbon atoms, and they may be the same or each other. may be different, and R1 is a hydrogen atom and has 1 to 1 carbon atoms.
The cationic constituent position represented by the alkyl group or benzyl group of 4, X1e is a negative ion), (B) anionic constituent unit, and (C) nonionic constituent unit are used in the sludge dehydrating agent of the present invention. In the sludge dewatering agent containing an amphoteric polymer having an amphoteric polymer as an active ingredient, the cationic structural unit of the unit (A) is contained in the amphoteric polymer (D) General formula... (I[) (Formula R4 and R1 are each an alkyl group having 1 to 4 carbon atoms, and may be the same or different, and R is a hydrogen atom and an alkyl group having 1 to 4 carbon atoms.
The present invention provides a sludge dehydrating agent characterized in that it contains 1 to 5 mol% of a cationic structural unit represented by the following: alkyl group or benzyl group of 4, X and e are negative ions.

The present invention will be explained in detail below.

... It has a structure represented by (I). R and R2 in the general formula (I) are each an alkyl group having 1 to 4 carbon atoms, i.e., a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a 5ec-butyl group, and It is a t-butyl group, and R8 and R2 may be the same or different.

f-R, is a hydrogen atom, the above-mentioned alkyl group having 1 to 4 carbon atoms, or benzyl group, and X. are halogen ions such as chloride ions, bromide ions, and iodine ions, H3O4'
-1so4''-1NO, -1CH, SO, - and other negative ions.

Examples of the seven polymers forming the cationic structural unit represented by the general formula (I) include dimethylaminoethyl acrylate, diethylaminoethyl acrylate, di-n-propylaminoethyl acrylate, di-isopropylaminoethyl acrylate, and di-n-propylaminoethyl acrylate. n-butylaminoethyl acrylate, di-5ec-butylaminoethyl acrylate, di-imbutylaminoethyl acrylate, methylethylaminoethyl acrylate, methylpropylaminoethyl acrylate, methylbutylaminoethyl acrylate, ethylpropylaminoethyl acrylate, ethylbutylamino Examples include, but are not limited to, neutralized salts with hydrogen halides, sulfuric acid, nitric acid, etc. such as ethyl acrylate and propyl butylaminoethyl acrylate, and quaternized products with alkyl halides, dimethyl sulfate, diethyl sulfate, etc. isn't it. Examples of the alkyl halide include methyl chloride, methyl bromide, methyl iodide, ethyl chloride, ethyl bromide, ethyl iodide, and benzyl chloride. These seven types may be used alone or in combination of two or more types.

Examples of monomers forming the anionic structural unit (B) in the amphoteric polymer include, but are not limited to, carboxylic acids having a vinyl group such as acrylic acid, methacrylic acid, and crotonic acid, and salts thereof. It's not a thing.

One type of these anionic monomers may be used, or two types may be used.
You may use combinations of more than one species.

Furthermore, the monomer forming the nonionic structural unit (C) is not particularly limited as long as it is nonionic and copolymerizable with the cationic heptamer and anionic monomer.

Such nonionic binders include, for example, vinyl group-containing amides such as acrylamide, methacrylamide, N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, and cyanogens such as acrylonitrile and methacrylatetrile. Vinyl compounds, alkyl esters of (meth)acrylic acid such as methyl acrylate, ethyl acrylate, methyl methacrylate, and ethyl methacrylate, vinyl esters of carboxylic acids such as vinyl acetate, styrene, a-methylstyrene , p-methylstyrene, and other aromatic vinyl compounds, but are not limited thereto, of course. One type of these nonionic columnar picks may be used, or two or more types may be used in combination. The amphoteric polymer has the above-mentioned (A) cationic structural unit, (B) anionic structural unit, and (C)
Based on the total amount of nonionic structural units, 10 to 80 mol%, 5 to 40 mol%, and 20 to 80 mol%, respectively.
It is desirable to contain it in a proportion of mol%. If the content of (A) cationic constituent sites is less than 10 mol%, the amount of cationic groups is small and the dehydration performance is poor, and if it exceeds 80 mol%, the amount of cationic groups is too large, making it preferable as an amphoteric polymer. character is lost. Furthermore, if the content of the anionic structural unit (B) is less than 5 mol%, the desirable properties as an amphoteric polymer will not be fully exhibited, and if it exceeds 40 mol%, the moisture content of the cake will increase and the cake peelability from the filter cloth will deteriorate. There is a tendency for the decline to become significant. Furthermore, if the content of the nonionic structural unit (C) deviates from the above range, the object of the present invention may not be fully achieved.

In the present invention, in order to improve the stability of the amphoteric polymer, it is necessary to contain 1 to 5 mol% of a cationic structural unit represented by the general formula % (). It is. R in the general formula (II)
3 and R are each an alkyl group having 1 to 4 carbon atoms, that is, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a 5ec-butyl group, and a t-butyl group; , R4 and R6 may be the same or different. Also R5
is a hydrogen atom, the above-mentioned alkyl group having 1 to 4 carbon atoms, or a benzyl group, and X2e is a halogen ion such as a chlorine ion, bromide ion, or iodide ion, ISO, -1so,
It is a negative ion such as -1NO3-1CHsSO,-.

Examples of the 7-mer forming the cationic constitutional entity represented by the general formula (I[) include dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, di-n-propylaminoethyl methacrylate, and di-isopropylaminoethyl methacrylate. , di-n-butylaminoethyl methacrylate, di-5ec-butylaminoethyl methacrylate, di-isobutylaminoethyl methacrylate, methylethylaminoethyl methacrylate, methylpropylaminoethyl methacrylate, methylbutylaminoethyl methacrylate, ethylpropylaminoethyl methacrylate , ethyl butylaminoethyl methacrylate, propyl butylaminoethyl methacrylate, etc., neutralized salts with hydrogen halides, sulfuric acid, nitric acid, etc., alkyl halides, quaternized products with dimethyl sulfate, diethyl sulfate, etc. It is not limited. Examples of the halogen alkyl include methyl chloride, methyl bromide, methyl iodide, ethyl chloride, ethyl bromide, ethyl iodide, and benzyl chloride. These monomers may be used alone or in combination of two or more.

If the content of the cationic structural unit represented by the general formula (II) in the amphoteric polymer is less than 1 mol%, the effect of improving stability will not be sufficiently exhibited, and if it exceeds 5 mol%, the effect of improving stability will not be exhibited. On the contrary, there is a tendency for stability to decrease.

The reason why amphoteric polymers are unstable is thought to be that the presence of cationic groups and anionic groups in the same molecule makes it easier for ionic reactions to occur. It is thought that as a result of the ionic reaction between the cationic group and the anionic group, the polymer assumes a crosslinked structure and becomes insolubilized (gelled).

The mechanism by which the stability is improved by the inclusion of the cationic structural unit represented by the general formula CI [) in the amphoteric polymer containing the cationic structural unit represented by the general formula (I) is not necessarily clear. However, by containing a small amount of the structure of general formula (II),
This is thought to be due to the change in the fungicide 3 of the polymer, making it difficult for ionic reactions to occur.

There are no particular restrictions on the method for producing the amphoteric polymer, and conventional solution polymerization, suspension polymerization, emulsion polymerization, etc.
Either method can be used. For example, in aqueous solution polymerization, ammonium persulfate,
A predetermined proportion of each of the above seven polymers may be polymerized using potassium persulfate, 2,2'-azobis(2-amidinopropane) hydrochloride, etc. under normal polymerization conditions.

Regarding the molecular weight of this amphoteric polymer, I
Intrinsic viscosity measured in N Na N Os aqueous solution [
V] should normally be 2 dL/9 or more, but desirably 5 dL/9 or more to achieve stable dehydration treatment.

There are no particular restrictions on the sludge to which the sludge dehydrating agent of the present invention is applied; for example, the sludge dehydrating agent can be applied to organic sludge generated in sewage, human waste, general industrial wastewater treatment, mixed sludge including flocculated sludge, etc. Can be done.

Furthermore, when using the sludge dehydrating agent of the present invention, it may be used in combination with other cationic polymers or anionic polymers, or may be used in combination with other cationic polymers or anionic polymers, or with polymers other than sodium hydrogen sulfate, sodium sulfate, sulfamic acid, etc. The components may be used in combination as long as they do not cause any adverse effects on the dehydration process, or in combination with inorganic flocculants such as sulfuric acid, polyaluminum chloride, ferric chloride, ferrous sulfate, and polyferrous sulfate. You can also.

Furthermore, in the treatment with the sludge dehydrating agent of the present invention, examples of dehydrators that can be used include belt press dehydrators, centrifugal dehydrators, screw press dehydrators, filter press dehydrators, and the like.

[Example] Next, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited in any way by these examples.

(Production Example 1 of D Amphoteric Polymer A quaternized product of dimethylaminoethyl acrylic-1-(DAA) with methyl chloride, acrylamide (AAm), sulfate of acryl a (AA) and dimethylaminoethyl methacrylate (DAM), Molar ratio 30:35
: 30 : 5, these were dissolved in water to prepare an aqueous solution with a total monomer concentration of 2.0 mol/1, and then three of these were placed in a rosebud flask and incubated at room temperature for 2.0 mol/1.
After degassing by bubbling nitrogen for 0 minutes, 0.01 mol% of potassium persulfate was added to the total amount of seven polymers, and polymerization was carried out at 45°C for 10 hours in a nitrogen atmosphere to form a transparent rubber-like amphoteric polymer. Got the gel. The intrinsic viscosity of this substance [+
y] was 7.2 dL/9. In addition, intrinsic viscosity [v]
In this example, a polymer prepared by powdering this polymer gel with acetone was added to an aqueous solution of IN-NaNOs for 3 hours.
This is a value measured at 0°C.

Examples 2 to 4, Comparative Examples 1 to 4 Same as Example 1, except that 7-mer with the composition shown in the t1g1 table was used, and potassium persulfate was used in a proportion of 0.01 to 0.20 mol%. An amphoteric polymer was prepared and its intrinsic viscosity [9] was determined. The results are shown in Table 1.

(2) Heat resistance stability test Half of the transparent rubber-like polymer gel obtained in (1) above was cut into cubes with sides of about 5 m #1 using scissors, and arranged on a stainless steel tray. 80 in a warm air dryer
After heating and drying at °C for 3 hours, the dried polymer was ground in a mortar to obtain a powdered polymer.

This powdered polymer was dissolved in pure water, and its solubility (dissolution state S) after 24 hours was evaluated. The results are shown in Table 2.

(3) Temporal stability test (I) The remaining half of the transparent rubber-like polymer gel obtained in (1) above was shredded using scissors in a large amount of acetone, dehydrated, and then vacuum dried. A powdered polymer was obtained.

Next, this powdered polymer was placed in a sunglass bottle, sealed tightly, and placed in a thermostat at 40° C. to perform a stability test over time of the powdered polymer. Immediately after powdering, held at 40°C for 1 month, held at 40°C for 2 months, and 40°C
were kept for 3 months, dissolved in pure water, and
The solubility (dissolution state) after 4 hours was evaluated. The results are shown in Table 3.

(4) Temporal stability test (I[) The powdered polymer obtained in (3) above was dissolved in city water to a concentration of 0.2 wt%, and the beaker containing this polymer aqueous solution was placed in a constant temperature water bath at 30°C. A stability test over time was conducted at a constant temperature. Immediately after powdering, 3 days later, and 7 days later, the solution viscosity was measured and evaluated using a B-type viscometer. The results are shown in Table 4.

(5) Agglomeration/dehydration test The following agglomeration/dehydration test was conducted using the polymer of Example 1 obtained in the above (2) and powdered by heating and drying at 80° C. for 3 hours.

Mixed sewage sludge (pI (5,9,
Conductivity 2150μs/cta, SS 1-6%,
VSS15576.3%, fiber content/5S24.6%)2
00*11 was added thereto, and the above polymer aqueous solution with a concentration of 0.4 wt% was added so that the amount of polymer added was 120 ppm, and the mixture was heated at 75 Orp using a stirrer with turbine blades.
The sludge was flocculated by stirring at m for 60 seconds. After measuring the size of the agglomerates at this time,
Pour this flocculated sludge into a narrow funnel and measure the amount of liquid after 10 seconds. Next, a certain amount of sludge on the Buchner funnel was sandwiched between two pieces of filter cloth, and 0.5 kg 7 cm
The moisture content of the cake was determined by squeezing it for 60 seconds at a pressure of

As a result, the floc diameter was 5 to 6 mm, the amount of filtrate after 10 seconds was 115 ml, and the cake water content was 80.7 wt%, confirming that the polymer had good performance.

(Left below) C Effects of the Invention The sludge dewatering agent of the present invention has an amphoteric polymer as a night-acting component, which has excellent flocculation and dewatering performance as well as excellent stability with little thermal deterioration and aging deterioration. Amphoteric polymers have extremely high stability, which prevents thermal deterioration (gelation) during the heat drying process during the production of powdered amphoteric polymers, and also prevents aging of powdered amphoteric polymer products and aqueous solutions of amphoteric polymers. It has extremely high industrial value.

Claims (1)

[Claims] 1 (A) General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (R_1 and R_2 in the formula are each an alkyl group having 1 to 4 carbon atoms, and they are the same. It's good too,
(They may be different from each other, R_3 is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a benzyl group, and X_1^■ is a negative ion); and (B) an anionic structural unit. (C) In a sludge dewatering agent whose active ingredient is an amphoteric polymer containing a nonionic structural unit, the amphoteric polymer contains (D) general formula ▲ mathematical formula, chemical formula, table, etc. ▼ (R_4 in the formula and R_5 are each an alkyl group having 1 to 4 carbon atoms, and they may be the same,
R_6 is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a benzyl group, and X_2^■ is a negative ion. A sludge dewatering agent characterized by: