JPH06254306A - Water-soluble high molecular flocculant - Google Patents

Abstract

PURPOSE:To provide a water-soluble high molecular flocculant being appropriately used in a waste water treatment, etc., whose flocculation compacting property is excellent and solid separation is excellent, by incorporating a high polymer compound being formed by grafting a specific acryl amide copolymer to a principal polymer of polysaccharide as a side chain, as an effective component. CONSTITUTION:The water-soluble high molecular flocculant incorporates the high polymer compound formed by grafting a copolymer of (a) acryl amide and/or methacryl amide with (b) at least one kind selected among an acrylic acid, a methacrylic acid and these salts to the principal polymer of the polysaccharide as the side chain.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a novel water-soluble polymer flocculant, and more specifically, it has better flocculation compaction and solid-liquid separation than conventional polymer flocculants. The present invention relates to a water-soluble polymer flocculant suitably used in the field of civil engineering such as construction and dredging landfill.

[0002]

2. Description of the Related Art Conventionally, coagulation treatment of sewage and general industrial wastewater,
Alternatively, polymer flocculants are widely used for treating muddy water at civil engineering sites and for facilitating sedimentation and separation of muddy water at the time of dredging. The polymer flocculant generally contains polyacrylamide or a polyacrylamide partially hydrolyzed to have anionic property (including a copolymer of acrylamide and sodium acrylate) as an active ingredient. is there. However, these acrylamide-based flocculants have excellent cohesiveness and excellent characteristics of forming large floc flocs, but on the other hand, they have the following drawbacks, and their improvement is desired. ing.
That is, the floc formed by a general acrylamide flocculant has a low density because the flocs are formed in a state of containing a large amount of water.
Therefore, when the aggregated sludge of waste water or muddy water is settled and concentrated, the flocs are not consolidated and the sludge volume does not decrease easily, which is an undesirable situation.
As a result, when the supernatant is separated from the coagulated sludge and the solid content is disposed of, the high water content makes it difficult to carry the material, and the treatment cost is high. The problem is that it becomes significantly worse. In addition, at the dredged landfill site, soil and sand are collected from the bottom of the seabed, lakes, ponds, coasts,
We are reclaiming the lake shore. In this case, an acrylamide polymer flocculant is added to the pumped slurry-like earth and sand to make it floc, the solid content (earth and sand) is allowed to settle, and then the supernatant liquid is removed and landfilling is performed. At this time, if an acrylamide polymer flocculant is used, it is difficult to drain water from the accumulated sediment due to poor compaction, and it takes several months to several years to use the landfill, so improvement is required. Is the current situation.

[0003]

The present invention overcomes the drawbacks of the conventional acrylamide type flocculants,
The purpose of the present invention is to provide a water-soluble polymer flocculant having good aggregation compaction property, good solid separation, and suitably used in the field of civil engineering such as wastewater treatment or construction and dredging landfill.

[0004]

Means for Solving the Problems As a result of intensive studies to develop a water-soluble polymer flocculant having the above-mentioned preferable properties, the present inventors have found that a backbone polymer of a polysaccharide has a specific side chain. It has been found that an aggregating agent containing a polymer compound obtained by grafting an acrylamide type comonomer as an active ingredient can meet the purpose, and based on this finding, the present invention has been completed. That is, the present invention provides a polysaccharide trunk polymer comprising (a) acrylamide and / or methacrylamide as a side chain and (b) at least one selected from acrylic acid, methacrylic acid and salts thereof. The present invention provides a water-soluble polymer flocculant containing a polymer compound obtained by grafting a copolymer as an active ingredient.

The present invention will be described in detail below. The water-soluble polymer flocculant of the present invention comprises, as an active ingredient, a polymer compound obtained by grafting an acrylamide comonomer as a side chain onto a polysaccharide trunk polymer.
The polysaccharide is not particularly limited, but preferred examples include polysaccharides such as starch, amylose, cellulose, carboxymethylcellulose, methylcellulose, guar gum, xanthan gum, pullulan, dextran, mannan, glucomannan, chitin, and chitosan, or derivatives thereof. it can. These polysaccharides may be used alone or in combination of two or more.

The polymer compound may have any structure as long as it has a structure in which a copolymer of the component (a) and the component (b) is grafted as a side chain onto the polysaccharide trunk polymer. Is not particularly limited, and may be obtained by any method, but in particular,
(1) Polysaccharides obtained by graft-copolymerizing acrylamide and / or methacrylamide and then partially hydrolyzing, and (2) Polysaccharides, acrylamide and / or methacrylamide, and acrylic acid, Those obtained by graft-copolymerizing at least one selected from methacrylic acid and salts thereof are suitable. The graft copolymerization method in the above (1) and (2) is not particularly limited, and a known method, for example, a method by irradiation with radiation or ultraviolet rays, or a method by an initiation reaction of a redox system using cerium ion (IV) Can be used, but it is advantageous because the method by the initiation reaction of the redox system using cerium ion (IV) can be carried out easily.

For example, a polysaccharide is dissolved in water (some saccharides may require heating when dissolved) or dispersed therein, and then a desired amount of a desired monomer is charged therein, followed by deoxygenation by blowing nitrogen, etc., and then a predetermined amount of cerium. By adding an ionic (IV) solution and polymerizing at a temperature of 0 to 40 ° C,
A graft copolymer is obtained. The content ratio of the polysaccharide segment and the side chain monomer unit in this graft copolymer is preferably in the range of 0.1: 99.9 to 30:70 in molar ratio. When the content of the polysaccharide segment is less than the above range, the intended function of the present invention is not sufficiently exerted, and when the content exceeds the above range, the proportion of side chains contributing to aggregation is reduced, and the same as the purpose of the present invention. The function to do is not fully exerted. Furthermore, in the case of the above (1), after graft-copolymerizing acrylamide and / or methacrylamide on the polysaccharide, it is partially hydrolyzed to give (meth)
It is necessary to partially replace the acrylamide units with (meth) acrylic acid units or their salt units. As the partial hydrolysis conditions, usual hydrolysis conditions of polyacrylamide under alkaline conditions can be used. Hydrolysis of the polysaccharide occurs under acidic conditions, and the trunk polymer is reduced in molecular weight, which is not preferable.

In the polymer compound thus obtained, the content of the (meth) acrylic acid unit in the side chain (branch) portion and its salt unit is preferably 5 mol% or more.
The molecular weight may be any level as long as it has an aggregating action, and for example, the temperature of 30 ° C., which is an index of the molecular weight,
It is desirable that the intrinsic viscosity in the N-sodium chloride aqueous solution is 4 dl / g or more. The water-soluble polymer flocculant of the present invention contains the polymer compound as an active ingredient, and the product form thereof is not particularly limited, and the partially hydrolyzed solution may be directly used as a liquid product, or heated. You may use it by powdering by drying or solvent precipitation. As a method of using the coagulant of the present invention, a predetermined amount of a 0.2 to 1.0% by weight solution of the coagulant is added to waste water or muddy water to coagulate. Further, an inorganic coagulant may be added if necessary. Examples of the inorganic coagulant include aluminum sulfate, polyaluminum chloride, polyiron sulfate, ferric chloride and the like. Furthermore, if necessary, the flocculant of the present invention may be used in combination with other general flocculants (for example, a partial hydrolyzate of polyacrylamide).

[0009]

When the flocculant of the present invention is used, the reason why flocs having a high density are formed and the compaction of the flocculated sludge is increased is not always clear. The molecular spread is smaller than that of the macromolecular flocculant, resulting in higher density of flocs. (2) Since the polysaccharide segment is contained in the flocculant, the hydrogen bond by its -OH group causes Being a tighter flock,
(3) Polysaccharides generally have a low molecular weight due to microbial decomposition. However, in the product of the present invention, it is also considered that the polysaccharide segment present in the polymer is subjected to microbial decomposition and the polymer has a low molecular weight to improve the compactness.

[0010]

The present invention will be described in more detail by way of examples, which should not be construed as limiting the invention thereto. Production Example 1 After dissolving a predetermined amount of polysaccharide in pure water (heating as necessary), a predetermined amount of acrylamide was added and dissolved therein, and the total amount was 200 ml. Then, the solution was provided with a stirrer, a cooler, a thermometer, and a nitrogen introducing tube.
The mixture was transferred to a 00 ml separable flask, and nitrogen bubbling was performed at room temperature for 2 hours to deoxygenate.

Then, a 0.1M solution of cerium (IV) in which cerium ammonium nitrate was dissolved in 1M nitric acid was added, and graft polymerization was carried out at 30 ° C. under a nitrogen atmosphere while stirring for 10 hours. The obtained polymer aqueous solution gel was put into methanol, cut into pieces, dehydrated and purified, and then vacuum dried to obtain a powder polymer. By measuring this weight, the yield was determined, the intrinsic viscosity (in 1N-NaCl aqueous solution, 30 ° C.) was determined, and the composition of the graft polymer was determined by elemental analysis. Next, the powder polymer thus obtained is dissolved in pure water, and then a 2 wt% NaOH aqueous solution 40 is added.
Add 1 ml of a 1% by weight aqueous solution of polymer 500
A milliliter was prepared and then hydrolyzed at 50 ° C. for 1 hour to be anionized. After 1 hour of reaction, the reaction solution was immediately cooled in a freezer to stop the reaction, and stored in a refrigerator.
Methanol was added to a part of this solution, N was quantified by measuring intrinsic viscosity (1N-NaCl aqueous solution, 30 ° C.) and elemental analysis using a powdered polymer obtained by purification, and the polymer composition was determined. For the aggregation test and the consolidation test, a hydrolyzed polymer solution (stored in a refrigerator) was prepared at 0.2% by weight and used. Regarding the above, Table 1 shows the details of the conditions and the analysis results.

[0012]

[Table 1]

Note 1) 30 ° C. in 1N-NaCl aqueous solution 2) Soluble starch 3) Pullulan having a molecular weight of 200,000 4) AAm: acrylamide, AA-Na: sodium acrylate

Example 1 Using the polymers shown in Table 1, an aggregation test and a consolidation test were carried out by the following methods. In a 500 ml beaker,
Take 500 ml of dredged sludge water diluted to 5% SS, add polyaluminum chloride (hereinafter abbreviated as PAC) while stirring at 150 rpm with a jar tester, and adjust the PAC of the turbidity of the supernatant to 5 or less. The required amount was calculated. Next, the amount of PAC determined here was added to the muddy water while stirring with a jar tester at 150 rpm, and then the polymer was added and immediately stirred at a stirring speed of 50 rpm for 2 minutes. Stirring was stopped and the sedimentation rate of flocs was measured to determine the relationship between the amount of polymer added and the sedimentation rate of flocs.

Then, the muddy water obtained by adding the polymer and aggregating it was transferred to a 500 ml graduated cylinder, and the change in the sludge volume with time was measured to evaluate the compaction property. The muddy water used here has a sand content of 68.
w / w%, silt content 22w / w%, clay content 10w / w%
Met. FIG. 1 shows the relationship between the amount of polymer added and the flocculation rate, and FIG. 2 shows the data of the change over time in the sludge volume. Example 2 It carried out like Example 1. The polymer used here had the property of -2, and the muddy water had a sand content of 8.2 w /
The content was w%, the silt content was 69.9 wt%, and the clay content was 24.9 w / w%. FIG. 3 shows the relationship between the amount of polymer added and the flocculation rate, and FIG. 4 shows the time-dependent change data of sludge volume.

Comparative Example 1 The following polymer was used as a comparative polymer, and the same procedure as in Example 1 was carried out. The results are shown in FIGS. Ratio-1: Evolution-1 Before Polymer Hydrolysis Ratio-2 (Partially Hydrolyzed Polyacrylamide): Acrylamide Unit / Sodium Acrylate Unit Molar Ratio 18
/ 82, intrinsic viscosity 23.0 dl / g Comparative Example 2 Using the polymers of ratio-1 and ratio-2 in Comparative Example 1,
It carried out on the same conditions as Example 2. The results are shown in FIGS. 3 and 4.

[0017]

EFFECTS OF THE INVENTION The flocculant of the present invention has a higher flocculation compaction property and a better solid-liquid separation than conventional polymer flocculants. Therefore, by using the flocculant of the present invention, (1)
Reduced turbidity of treated water (2) Reduced sludge volume (improved sludge compaction), resulting in reduction of sludge disposal time and treatment cost (3) Improved consolidation of dredged land It has the effect of

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the amount of polymer added and the floc sedimentation rate in Example 1 and Comparative Example 1.

FIG. 2 is a graph showing changes over time in sludge volume in Example 1 and Comparative Example 1.

FIG. 3 is a graph showing the relationship between the amount of polymer added and the floc sedimentation rate in Example 2 and Comparative Example 2.

FIG. 4 is a graph showing changes over time in sludge volume in Example 2 and Comparative Example 2.

Front page continued (72) Inventor Shigeru Sato 3-4-7 Nishi-Shinjuku, Shinjuku-ku, Tokyo Kurita Industry Co., Ltd.

Claims (1)

[Claims] 1. A polysaccharide backbone polymer having (a) as a side chain.
Acrylamide and / or methacrylamide, (b)
A water-soluble polymer flocculant comprising a polymer compound obtained by grafting a copolymer with at least one selected from acrylic acid, methacrylic acid and salts thereof as an active ingredient.