JPH09810A - Method for producing coagulant aqueous solution - Google Patents

Abstract

PURPOSE: To provide a method to quickly prepare an aqueous flocculant solution which contains a polymer flocculant at high concentration, has excellent flocculating function and low viscosity, and by which flocculated flocs are excellently formed at the time of use. CONSTITUTION: A polymer flocculant, preferably polyacrylamide-based polymer flocculant, is dissolved in an aqueous solution of a water-soluble inorganic salt having 0.1-10wt.% of concentration on a ratio of 25-200 pts.wt. of the f1 occulant based on 100 pts.wt. of the water-soluble inorganic salt.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing an aqueous flocculant solution.

[0002]

2. Description of the Related Art Conventionally, as a method of treating various industrial wastewater such as mine wastewater, ready-mixed concrete factory wastewater, construction site mud wastewater, etc., a flocculant is added to this to coagulate suspended particles and dehydrate it. It is made into a solid. At that time, as the above-mentioned aggregating agent, a water-soluble inorganic salt, a polymer aggregating agent, and the like are known, and a polymer aggregating agent is particularly useful because of its high aggregating effect. These coagulants are preferably added to the wastewater as an aqueous solution in order to enhance the homogeneity of the reaction.

However, the above-mentioned polymer flocculant usually has a large molecular weight ranging from several millions to several tens of millions and its solubility in water is extremely poor. Therefore, it is generally used as an aqueous solution of about 0.1% by weight, but even with such a low concentration, preparation requires a long time under stirring. Moreover,
The obtained aqueous solution has a high viscosity and is inferior in handleability, and it is difficult to uniformly mix it with wastewater, and in some cases, sufficient coagulation performance cannot be exhibited.

[0004]

Under these circumstances, in JP-A-56-139109, in order to improve the solubility of a polymer flocculant, a polymer flocculant and a water-soluble inorganic salt are treated as a polymer flocculant. It is described that 1 to 30 parts by weight of the water-soluble inorganic salt is used in combination with 1 part by weight of the agent. Here, in the publication, the polymer flocculant and the water-soluble inorganic salt are
It is added to water at the same time. However, in the aspect in which such a polymer flocculant and a water-soluble inorganic salt are added to water at the same time, the improvement of the solubility is not sufficient, and as described in Examples, the polymer flocculant in an aqueous solution is not dissolved. If the concentration is about 0.1% by weight, it is possible to dissolve the polymer coagulant in a short time to some extent, but if the concentration of the polymer coagulant becomes higher than that, it can still be satisfied. No solubility was obtained.

On the other hand, in JP-A-55-127109 and JP-A-58-74106, a polymer flocculant is dispersed in a concentrated solution of a water-soluble inorganic salt of about 20% or more. A method of adding water to dissolve it is disclosed. However, since this method uses a concentrated solution of a water-soluble inorganic salt, the amount of the polymer flocculant used relative to the water-soluble inorganic salt is 0.2 to 20 parts by weight based on 100 parts by weight of the water-soluble inorganic salt. And less. According to the findings of the present inventors, when the amount of the polymer flocculant used is small as described above, when the resulting flocculant aqueous solution is subjected to the coagulation treatment of the waste water, the coagulum becomes fine. The miniaturization of such agglomerates is particularly remarkable when the wastewater contains fine particles such as silt and clay, and in such wastewater, when the agglomerates are miniaturized, the filter cloth is clogged and solidified. It becomes difficult to separate the liquid, and in the centrifugal filter, the operation itself of the machine is likely to be disturbed by decentering the rotating body.

From the above background, a method for rapidly producing a coagulant aqueous solution containing a high-molecular-weight coagulant at a high concentration, having a good coagulation action, having a low viscosity, and forming a good coagulum at the time of use Was desired to be developed.

[0007]

[Means for Solving the Problems] The inventors of the present invention have conducted extensive research to solve the above problems. As a result, they have found that the above problems can be solved by dissolving a polymer flocculant in a water-soluble metal salt aqueous solution having a specific concentration in a specific ratio, and have completed the present invention.

That is, in the present invention, 25 to 200 parts by weight of the polymer flocculant is dissolved in 100 parts by weight of the water-soluble inorganic salt in an aqueous solution of the water-soluble inorganic salt having a concentration of 0.1 to 10% by weight. And a method for producing an aqueous coagulant solution.

In the present invention, known water-soluble inorganic salts can be used without any limitation. Such a water-soluble inorganic salt has an action of helping dissolution of the polymer flocculant and lowering the viscosity of the solution. In addition, when the obtained coagulant aqueous solution is used, it also has the effect of promoting the coagulation reaction of the polymer coagulant. Examples of such water-soluble inorganic salts include chlorides, sulfates, nitrates and ammonium salts of alkali metals and alkaline earth metals. Specific examples include magnesium chloride, calcium chloride, sodium chloride, potassium chloride, sodium nitrate, potassium nitrate, magnesium sulfate, ammonium sulfate, ammonium chloride, ammonium nitrate and the like. Of these, it is particularly preferable to use calcium chloride.

On the other hand, in the present invention, known polymer flocculants can be used without any limitation. These may be cationic, anionic, or nonionic, but from the viewpoint of improving solubility, anionic having poor solubility,
It is particularly effective for nonionic substances. Specifically, polyacrylic amide, partially hydrolyzed polyacrylic amide, modified polyacrylic amide, partially modified polyacrylic amide, copolymer of acrylic amide and acrylate, polyvinyl pyridine, polyethyleneimine, diallyl Examples thereof include ring polymers of ammonium halides, synthetic polymer flocculants such as carboxymethyl cellulose and chitosan, natural polymer flocculants, and the like. Of these, polyacrylic amide type is preferable.

In the present invention, the polymer flocculant is dissolved in the aqueous solution of the water-soluble inorganic salt. As a result, the polymer flocculant has significantly improved solubility as compared with the case where these components are simultaneously dissolved in water, and the viscosity of the solution can be suppressed low. At that time, the concentration of the aqueous solution of the water-soluble inorganic salt was 0.
It is necessary to make it 1 to 10% by weight, preferably 0.2 to 4% by weight. When the concentration of the water-soluble inorganic salt is less than 0.1% by weight, the effect of improving the solubility of the polymer coagulant becomes insufficient. On the other hand, when the concentration is more than 10% by weight, it becomes difficult to dissolve the polymer flocculant at the compounding ratio of the water-soluble inorganic salt and the polymer flocculant described later.

In the present invention, the amount of the polymer flocculant dissolved in the aqueous solution of the water-soluble inorganic salt is 25 to 200 parts by weight, preferably 30 to 15 parts by weight based on 100 parts by weight of the water soluble inorganic salt.
0 parts by weight. With this blending amount, an aqueous flocculant solution having a good flocculating action can be obtained. In particular, large aggregates are formed during use, which is preferable. Here, if the amount of the polymer flocculant dissolved is less than 25 parts by weight, aggregates formed during use become fine, which is not preferable. On the other hand, if the amount of dissolution is more than 200 parts by weight, the solubility is lowered and the liquid becomes too viscous, which is not preferable.

The temperature of the aqueous solution of the water-soluble inorganic salt when the polymer flocculant is dissolved is not particularly limited, but usually 10 to 40 ° C. is preferable. Further, it is preferable to stir the liquid when dissolving.

In the present invention, the produced flocculant liquid is
It can be used without any limitation when coagulating and dewatering waste mud water discharged as various industrial waste water. Particularly, it is suitable to be applied to waste mud water containing fine soil particles and cement such as ready-mixed concrete factory waste water and construction site mud waste water.

[0015]

According to the present invention, an aqueous flocculant solution in which a polymeric flocculant is dissolved can be rapidly produced with good solubility. In addition, the obtained coagulant aqueous solution has a low viscosity, and can be directly mixed with the solution to be coagulated with good handleability. Further, such an aggregating agent aqueous solution has a good aggregating action, and a large aggregate is formed, which is extremely useful.

[0016]

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

Example 1 1 L of an aqueous solution containing 5.0 g of calcium chloride and 5.0 g of magnesium chloride (calculated as anhydrous salt) was stirred and powdered anionic polyacrylic amide polymer flocculant (manufactured by Sumitomo Chemical Co., Ltd.). 5.0 g of "Sumifloc FA70") was added. The polymeric flocculant was completely dissolved after 30 minutes. The viscosity of the obtained coagulant aqueous solution was 25 cP.

Next, a clay containing a large amount of fine particles which are usually said to be extremely difficult to coagulate and dehydrate (“Kasaoka C-200” manufactured by Toyo Bentonite Co., Ltd., 200 mesh,
When the above flocculant aqueous solution (3.0 mL) was added to 100 g of clay mud water containing 25% (74 μm or less) and stirred and mixed, immediately colorless and transparent supernatant water and strong flocs (aggregates) having a maximum particle size of 5 mm were generated. The supernatant water and flocs were transferred to the inner bag (saran fiber, mesh opening 250μ) of a tabletop centrifugal filter with a perforated basket having a diameter of 10 cm, a height of 6 cm, and a hole diameter of 2 mm, and a centrifugal force of 900 G was applied to the inner bag to give 100
As a result of holding for 2 seconds and dehydrating, colorless and transparent filtrate and water content 3
A 5.0% dehydrated cake was obtained.

Examples 2 to 10 Except that the type and amount of each of the water-soluble inorganic salt and the polymer flocculant used in Example 1 were changed to those shown in Table 1,
An aqueous coagulant solution was produced in the same manner as in Example 1, and the aggregation effect was tested in the same manner. The results are shown in Table 1.

Comparative Example 1 An aqueous flocculant solution was produced in the same manner as in Example 1 except that the inorganic salt and the polyacrylic amide polymer flocculant were added simultaneously to water. The results are shown in Table 2.

Comparative Example 2 An aqueous flocculant solution was prepared in the same manner as in Example 1 except that the amount of the polyacrylic amide type polymer flocculant used was 10 parts by weight based on 100 parts by weight of the inorganic salt. It was manufactured and the aggregation effect was tested in the same manner. The results are shown in Table 2.

Comparative Example 3 An aqueous coagulant solution was prepared in the same manner as in Example 1 except that the amount of the polyacrylic amide polymer coagulant used was 250 parts by weight per 100 parts by weight of the inorganic salt. Manufactured. The results are shown in Table 2.

[0023]

[Table 1]

[0024]

[Table 2]

Claims (1)

[Claims] 1. In an aqueous solution of a water-soluble inorganic salt having a concentration of 0.1 to 10% by weight, the amount is 25 to 25 parts by weight based on 100 parts by weight of the water-soluble inorganic salt.
A method for producing an aqueous flocculant solution, which comprises dissolving 200 parts by weight of a polymeric flocculant.