JP2014184416A - Flocculant composition and method of treating polluted water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flocculant composition which can quickly and easily treat polluted water.SOLUTION: A flocculant composition for treatment of radioactive polluted water comprises anionic polymer flocculant, cationic polymer coagulant, natural zeolite, and aluminum sulfate. 50 mass% or more of the aluminum sulfate is 0.15 mm or less in particle diameter.

Description

  The present invention relates to a flocculant composition and a method for treating contaminated water.

  Contaminated water discharged in civil engineering works and factories is treated by coagulating and precipitating pollutants contained in the contaminated water over time in a dedicated plant and then separating the flocs that have been agglomerated and precipitated. As an aggregating agent used when coagulating and precipitating contaminants, polyaluminum chloride (PAC), aluminum sulfate (sulfuric acid band) and the like are used (see Patent Documents 1 and 2).

JP 2004-305893 JP 2009-248006 A

  By the way, an aggregation rate is mentioned as a characteristic calculated | required by the flocculant. In particular, radioactively contaminated water containing radioactive substances such as cesium is strongly required to be processed quickly in order to suppress the diffusion of radioactive substances. However, the flocculants disclosed in Patent Documents 1 and 2 do not have a sufficient aggregation rate.

  Then, an object of this invention is to provide the coagulant | flocculant composition which can process contaminated water quickly and easily, and the processing method of contaminated water.

  In order to achieve the above object, the present invention includes an anionic polymer flocculant, a cationic polymer flocculant, natural zeolite, and aluminum sulfate, and 50% by mass or more of the aluminum sulfate is granulated. Provided is a flocculant composition for treating contaminated water having a diameter of 0.15 mm or less.

  The flocculant composition contains an anionic polymer flocculant, a cationic polymer flocculant, natural zeolite, and aluminum sulfate that satisfies the above particle size conditions. Thus, contaminated water can be treated quickly and easily.

  Regarding the reason why the contaminated water is quickly and easily treated, the present inventors presume that the inclusion of aluminum sulfate satisfying the above particle size condition is particularly effective. Most of the fine suspended matter (soil in the water) present in the water has a negative charge around the material, the fine particles repel each other, and are difficult to settle due to Brownian motion. When aluminum sulfate that satisfies the above particle size conditions is added, positively charged aluminum ions are quickly generated, which react with the negative charge on the surface of the suspended particulates to bind the particulates and facilitate precipitation. be able to. Then, by adding an anionic polymer flocculant to the suspended matter aggregated to a certain size by aluminum sulfate, the suspended matter becomes larger due to its crosslinking action, and flocs are formed and precipitate. . Further, when a cationic polymer flocculant is further added to the floc aggregated by the anionic polymer flocculant having a negative charge, a larger and stronger floc is formed and more easily precipitates. In addition, natural zeolite becomes the core of the floc and can increase the weight of the floc to make it easier to precipitate. The rate at which this series of coagulation precipitation occurs is greatly affected by the negative charge neutralization rate and coagulation rate of the initial suspended solids by aluminum sulfate, and the rate is greatly improved by using aluminum sulfate that satisfies the above particle size conditions. The contaminated water can be treated quickly and easily. Moreover, natural zeolite can obtain a good adsorption effect for radioactive substances dissolved in water such as cesium ions. For this reason, radioactive contamination water can be quickly processed with a radioactive substance by using together with the aluminum sulfate which satisfy | fills the said particle size condition.

  Conventionally, aluminum sulfate fine particles having a particle diameter of 0.15 mm or less have been discarded when producing aluminum sulfate. However, in the above flocculant composition, the production cost of the flocculant composition can be reduced in that the fine particles discarded so far can be used. In addition, the flocculant composition does not need to be dissolved in water and then mixed into the contaminated water, and the above-described effect can be achieved by adding it to the contaminated water as it is. Therefore, the trouble of treating contaminated water can be saved.

  The flocculant composition preferably further contains a carbonate. Thereby, the contaminated water can be treated more quickly and easily.

  The carbonate preferably contains sodium carbonate. Since aluminum sulfate becomes acidic when dissolved in water, the flocculant composition tends to precipitate when it is alkaline. For this reason, contaminated water can be processed more quickly and easily because the flocculant composition contains alkaline sodium carbonate.

  The carbonate preferably contains calcium carbonate. By containing calcium carbonate, the weight of the aggregated precipitate can be increased, and the contaminated water can be treated more quickly and easily by the flocculant composition.

  The flocculant composition preferably further contains an organic acid. When an anionic polymer flocculant and a cationic polymer flocculant are dissolved in contaminated water at the same time, they may react to form a polymer mass. Generation of molecular lumps can be suppressed. As a result, the anionic polymer flocculant and the cationic polymer flocculant can sufficiently exhibit the aggregating ability with respect to the contaminated water.

  The organic acid preferably contains at least one selected from the group consisting of malic acid, sulfamic acid, oxalic acid, citric acid and tartaric acid. By using these organic acids, it is possible to more sufficiently inhibit the anionic polymer flocculant and the cationic polymer flocculant from reacting to form a lump.

  The zeolite used in the present invention is a natural zeolite. Since natural zeolite is porous, it has high water absorption and has a density suitable for precipitation, so it tends to be a core of aggregated flocs. Natural zeolite is suitable as a material for the flocculant composition because of its low price. When natural zeolite becomes the core of floc, the weight of floc increases and precipitation can be more easily generated. When natural zeolite is used, it can have a more excellent adsorption / aggregation effect on radioactive substances.

  The present invention is also a method for coagulating contaminated water using the above-described coagulant composition of the present invention, wherein the coagulant composition is added to the contaminated water and stirred to coagulate and precipitate the pollutant. Provided is a method for aggregating contaminated water, which comprises a step of separating contaminated water into a precipitate and a supernatant. In such a manufacturing method, contaminated water can be quickly and easily treated while aggregating contaminants contained in the contaminated water. Furthermore, in the above-described manufacturing method, radioactive contaminated water can be quickly adsorbed and coagulated together with radioactive substances.

  ADVANTAGE OF THE INVENTION According to this invention, the coagulant | flocculant composition which can process contaminated water quickly and easily, and the processing method of contaminated water can be provided.

It is a figure which shows schematic structure of the processing equipment for performing the processing method of contaminated water which concerns on this embodiment.

  Hereinafter, preferred embodiments of the flocculant composition and the method for treating contaminated water according to the present invention will be described in detail.

(Flocculant composition)
The flocculant composition is used to treat and purify contaminated water contaminated with contaminants such as heavy metals or radiation contaminated water contaminated with radiation materials. By draining the purified supernatant liquid, the volume of contaminated water or radioactive contaminated water can be reduced. In the present specification, the contaminated water means contaminated mud water that contains mud (turbidity) as a suspended substance and can be confirmed visually. However, radioactively contaminated water means contaminated mud water or contaminated water containing floating substances and / or ionic radioactive substances to which radioactive substances are attached. The flocculant composition can purify the supernatant liquid by aggregating floating substances to which radioactive substances present in water adhere, and can adsorb ionic radioactive substances dissolved in water. Examples of radioactive substances that can be adsorbed include cesium and strontium. The flocculant composition contains an anionic polymer flocculant, a cationic polymer flocculant, natural zeolite, and aluminum sulfate. Hereinafter, each component contained in the flocculant composition will be described.

  The anionic polymer flocculant is not particularly limited, and examples thereof include copolymers of acrylamide and (meth) acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, vinylsulfonic acid or salts thereof, and polyacrylamide. A partial hydrolyzate or the like can be used. Among them, it is preferable to use a compound having a molecular weight of several hundred thousand to several million. From the viewpoint of improving the aggregation effect, it is preferable to use a compound having a strong acid group such as a sulfonic acid group or a carboxylic acid group. These can be used individually by 1 type or in combination of 2 or more types.

  Although there is no restriction | limiting in particular as a cationic polymer flocculant, For example, acrylamide, and cationic monomers, such as dialkylaminoalkyl (meth) acrylate, dialkylaminoalkyl (meth) acrylamide, or these salts or quaternization products, are used. A copolymer or a homopolymer or copolymer of these cationic monomers can be used. From the viewpoint of improving the aggregation effect, it is preferable to use a compound having a strong base such as an amino group. These can be used individually by 1 type or in combination of 2 or more types.

  The total content of the anionic polymer flocculant and the cationic polymer flocculant in the flocculant composition is 2 to 20% by mass on the basis of the total amount of the flocculant composition from the viewpoint of obtaining an excellent aggregation rate. It is preferable that it is 5-10 mass%. The mass ratio of the anionic polymer flocculant and the cationic polymer flocculant is preferably 20: 1 to 20:12, and more preferably 10: 1 to 10: 5.

  As zeolite, natural zeolite is used. Natural zeolites include mordenite and clinoptilolite, and these can be used alone or in combination of two or more. Natural zeolite has an excellent adsorption / aggregation effect on radioactive substances dissolved in water such as cesium ions. Moreover, the radioactive polluted water can be treated quickly by containing natural zeolite in the flocculant composition and weighting the floc using the natural zeolite as a core. Since natural zeolite is porous, it has high water absorption and has a density suitable for precipitation, so it tends to be a core of aggregated flocs. Natural zeolite is suitable as a material for the flocculant composition because of its low price. When natural zeolite becomes the core of floc, the weight of floc increases and precipitation can be more easily generated.

  The content of the natural zeolite in the flocculant composition is 10 to 30% by mass based on the total amount of the flocculant composition from the viewpoint of obtaining an excellent adsorption effect on the radioactive substance and obtaining an excellent flocculence rate. Is preferable, and it is more preferable that it is 15-20 mass%.

  The particle size of the natural zeolite is preferably 500 μm or less, and particularly preferably 5 to 10 μm from the viewpoint of obtaining an excellent adsorption / aggregation effect for radioactive substances and obtaining an excellent aggregation rate.

  As for aluminum sulfate, 50 mass% or more of the total amount of aluminum sulfate contained in the flocculant composition needs to have a particle size of 0.15 mm or less. Since more than half of the aluminum sulfate contained in the flocculant composition is a fine particle having a particle size of 0.15 mm or less, it is possible to quickly agglomerate the contaminated water while having an aggregating effect on the contaminated water. Become. Further, from the viewpoint of further enhancing the effect of the present invention, 60 mass% or more of aluminum sulfate is preferably 0.15 mm or less in particle size, and more preferably 80 mass% or more is 0.15 mm or less in particle size. The total amount is most preferably 0.15 mm or less.

  In the present invention, whether or not the particle size of aluminum sulfate is 0.15 mm or less is confirmed by using a 100 mesh sieve (aperture 0.15 mm). The particles are 15 mm or less. That is, among the aluminum sulfate in the flocculant composition, the particles that have passed through the 100 mesh sieve may be 50% by mass or more of the total amount of aluminum sulfate.

  The content of aluminum sulfate in the flocculant composition is preferably 20 to 60% by mass based on the total amount of the flocculant composition from the viewpoint of obtaining an excellent aggregation effect and obtaining an excellent aggregation rate. More preferably, it is -40 mass%. Aluminum sulfate can be used alone or in combination of two or more.

  The flocculant composition preferably further contains a carbonate. Thereby, the contaminated water can be treated more quickly and easily. The carbonate preferably contains sodium carbonate. Since aluminum sulfate becomes acidic when dissolved in water, the flocculant composition tends to precipitate when it is alkaline. For this reason, contaminated water can be processed more quickly and easily because the flocculant composition contains alkaline sodium carbonate. Further, from the viewpoint of obtaining such effects more sufficiently, the content of sodium carbonate in the flocculant composition is preferably 20 to 50% by mass, based on the total amount of the flocculant composition, and is 30 to 40% by mass. More preferably.

  The carbonate preferably contains calcium carbonate. By containing calcium carbonate, the weight of the aggregated precipitate can be increased, and the contaminated water can be treated more quickly and easily by the flocculant composition. In addition, from the viewpoint of obtaining such effects more sufficiently, the content of calcium carbonate in the flocculant composition is preferably 3 to 20% by mass, based on the total amount of the flocculant composition, and is 7 to 12% by mass. More preferably.

  Examples of carbonates other than the above include calcium sulfate (gypsum) and the like. A carbonate can be used individually by 1 type or in combination of 2 or more types.

  The flocculant composition preferably further contains an organic acid. When an anionic polymer flocculant and a cationic polymer flocculant are added at the same time, they both react to form a polymer mass, but by adding an organic acid to the flocculant composition, In addition, it is possible to suppress the formation of the polymer mass and to coagulate the contaminated water more quickly. Further, from the viewpoint of obtaining such effects more sufficiently, the content of the organic acid in the flocculant composition is preferably 10% by mass or less, and 1 to 5% by mass based on the total amount of the flocculant composition. It is more preferable.

  The organic acid preferably contains at least one selected from the group consisting of malic acid, sulfamic acid, oxalic acid, citric acid and tartaric acid. The flocculant composition containing these organic acids can perform the flocculation treatment of contaminated water more quickly while exhibiting a sufficient flocculation effect on the radioactive substance. An organic acid can be used individually by 1 type or in combination of 2 or more types.

The flocculant composition can contain slaked lime (Ca (OH)), ferrous sulfate (FeSO ₄ ), and the like in addition to the components described above.

  The flocculant composition having the above-described configuration may be dissolved and / or dispersed in water as a single solution and then charged into contaminated water, but each component is premixed as a powdery material. It is more preferable to put it into contaminated water. The method for charging the flocculant composition into the contaminated water is not particularly limited.

  The amount of the flocculant composition used for the coagulation treatment of radioactive sludge is not unconditional because it varies depending on the type and concentration of radioactive substances and suspended substances in the contaminated water, but usually it is 1 L of radioactive contaminated water. 0.1 to 3.0 g, preferably 0.1 to 2.0 g, more preferably 0.7 to 1.0 g.

(Method of coagulation treatment of radioactive contaminated water)
The method for agglomeration treatment of radioactive contaminated water has a step of separating the radioactive contaminated water into a precipitate and a supernatant liquid by adding the above-mentioned flocculant composition to the radioactive contaminated water and stirring to agglomerate and precipitate the radioactive substance. Moreover, it is preferable that the said aggregation processing method has the process of draining or reusing the isolate | separated supernatant liquid. Furthermore, the agglomeration method preferably includes a step of dewatering the precipitate after draining the supernatant. FIG. 1 is a diagram illustrating a schematic configuration of an agglomeration processing facility for performing the agglomeration processing method according to the present embodiment. With reference to FIG. 1, a method for aggregating radioactive contamination water according to the present embodiment will be described.

  As shown in FIG. 1, a coagulation treatment facility for performing the coagulation treatment method includes a raw water tank 11, a coagulation sedimentation tank 12, a drain tank 13, and a dehydrator 14. The raw water tank 11 stores radioactive contaminated water to be treated, and the contaminated water is supplied to the coagulation sedimentation tank 12 via the pump P1. The coagulation sedimentation tank 12 is not particularly limited as long as it is a container that can accommodate a predetermined amount of contaminated water and can stir the contaminated water therein. In order to facilitate the movement of the coagulation sedimentation tank 12, a means such as a roller that can move forward and backward may be provided in the lower part. Moreover, the coagulation sedimentation tank 12 may have a lantern structure that can be folded up and down in order to reduce the occupied space before the contaminated water is accommodated and to facilitate the movement thereof. Furthermore, at least a part of the contaminated water in the coagulation sedimentation tank 12 may be formed of a transparent member so that the state of aggregation of the contaminated water can be visually confirmed from the outside of the coagulation sedimentation tank 12. Moreover, the side surface of the coagulation sedimentation tank 12 may be provided with a drain outlet for discharging the supernatant liquid at a position higher than the height of the generated precipitate. In addition, since the height of the generated precipitate is not necessarily constant, a plurality of drain outlets may be provided by changing the height direction stepwise.

  After supplying the contaminated water to the coagulating sedimentation tank 12, the above-mentioned coagulant composition is added to the contaminated water, and the contaminated water in the coagulating sedimentation tank 12 is stirred by the stirrer 12a. Thereafter, the stirring is stopped and the mixture is allowed to stand to separate the contaminated water into a precipitate 12b and a supernatant liquid 12c. The stirrer 12a is not particularly limited as long as it can uniformly dissolve and / or disperse the flocculant composition in the contaminated water. For example, a submersible pump, a Satake-type stirrer, Marzel (manufactured by Makita) or the like is used. Can do. In particular, it is more preferable if the flocculant composition can be dissolved and / or dispersed quickly and uniformly in the contaminated water. Although stirring time will not be specifically limited if it is time which can fully melt | dissolve and / or disperse | distribute a flocculant composition in contaminated water, Usually, it is 0.5 to 3 minutes, Preferably it is 1-2 minutes. The standing time is not particularly limited as long as the contaminated water is sufficiently separated into the precipitate 12b and the supernatant liquid 12c, but is usually 1 to 5 minutes, and preferably 0.5 to 2 minutes. Since the above-mentioned flocculant composition can perform the coagulation treatment of contaminated water quickly in a short time, the stirring time and the standing time can be shortened, and the work can be speeded up.

  The separated supernatant 12c is sucked up by the pump P2 and supplied to the drainage tank 13. The supernatant liquid 12c supplied to the drainage tank 13 is measured for radioactivity concentration in the drainage tank 13, and when the radioactivity concentration is below a certain level (for example, 10 Bq / kg or less), the supernatant liquid 12c is discharged from the drainage tank 13. Drained or reused.

  On the other hand, the precipitate 12b is dehydrated in the dehydrator 14, and the dehydrated cake-like sludge 15 is transported to a predetermined place by a belt conveyor or the like and discarded. Although it does not specifically limit as the dehydrator 14, For example, pressure dehydrators, such as press dehydrators, such as a belt press, a screw press, a filter press, or a centrifuge, a vacuum filter, can be used. In addition, the particle size of the sludge in the precipitate 12b is as fine as less than 0.075 mm.

  The present invention has been described in detail above based on preferred embodiments thereof. However, the present invention is not limited to the above embodiment. For example, in the above embodiment, the coagulation treatment facility includes the raw water tank 11, the coagulation sedimentation tank 12, the drain tank 13, and the dehydrator 14, but it is not always necessary to include all of them. For example, the agglomeration processing equipment includes only the agglomeration sedimentation tank 12, stores radioactive contaminated water directly in the agglomeration sedimentation tank 12, measures the radioactivity concentration of the supernatant liquid 12c in the agglomeration sedimentation tank 12, and the radioactivity concentration is constant. When it is below the standard, the supernatant liquid 12c may be drained from the coagulation sedimentation tank 12. Further, the movement of the contaminated water from the raw water tank 11 to the coagulation sedimentation tank 12 and the movement of the supernatant liquid 12c from the coagulation sedimentation tank 12 to the drainage tank 13 may not be performed via the pumps P1 and P2.

  Moreover, the coagulation treatment method for radioactively contaminated water of the present invention does not necessarily need to be performed by installing the coagulation treatment equipment as described above, and can be carried out with simple equipment. The flocculant composition and the contaminated water treatment method of the present invention are useful for treating contaminated mud water and contaminated water in general. However, since the agglomeration speed is fast and the adsorption / aggregation effect on radioactive substances is excellent, It is particularly useful for processing. In addition, it is also suitable for applications in which radioactive polluted water generated by decontamination work in areas contaminated with radioactive substances is subjected to agglomeration treatment at the site for each occurrence location to reduce the volume.

  Hereinafter, preferred examples of the present invention will be described in more detail, but the present invention is not limited to these examples.

(Examples 1-2 and Comparative Examples 1-3)
The components shown in Table 1 below were blended in the blending amounts (unit: parts by mass) shown in the same table to prepare flocculant compositions of Examples 1-2 and Comparative Examples 1-3.

In addition, the following were used as each component in Table 1.
Anionic polymer flocculant: iK Flock (Nippon Giken)
Cationic polymer flocculant: I-K-Flock (Nippon Giken)
Natural zeolite: Itaya zeolite (manufactured by Sieglite)
Aluminum sulfate A: The following aluminum sulfate B was finely pulverized with a mortar and passed through a 100 mesh (aperture 0.15 mm) sieve to obtain aluminum sulfate A (particle size 0.15 mm or less).
Aluminum sulfate B: Aluminum sulfate (average particle size 0.8 mm, minimum particle size 0.15 mm or more)
Calcium carbonate: Ube Materials Co., Ltd.

(Measurement of coagulation rate)
The coagulation treatment speed of contaminated water by the coagulant composition obtained in Examples and Comparative Examples was measured by the following method. As the contaminated water, there were prepared three kinds of contaminated water containing contaminated water containing 10000 ppm of viscous soil, contaminated water containing 10,000 ppm of bentonite, and contaminated water containing 10000 ppm of cement. 200 ml of this contaminated water was placed in a graduated cylinder having a capacity of 200 ml, 0.2 g of the flocculant composition was added thereto, stirred for 1 minute, and allowed to stand for a certain period of time to cause the contaminated water to coagulate and precipitate.

  Immediately after the flocculant composition was added to the contaminated water and stirring was completed, the mixture was allowed to stand for 3 minutes, then allowed to stand for 5 minutes, and then allowed to stand for 10 minutes, and then the amount of the produced supernatant was measured based on the scale of the graduated cylinder. . Here, it is assumed that the supernatant liquid is a portion where the turbidity has disappeared and it has been visually confirmed that the water has changed to almost transparent water. The greater the amount of the supernatant produced, the faster the flocculation process rate for the contaminated water of the flocculant composition. Table 2 shows the measurement results (unit: ml) of the amount of the supernatant along with the types of contaminated water.

(Verification experiment: agglomeration of zeolite with radioactive materials)
The components shown in Table 3 below were blended in the blending amounts (unit: parts by mass) shown in the same table to prepare flocculants AD.

In addition, the following were used as each component in Table 3. The same thing as each component in Table 1 was used except the following.
Artificial zeolite: fA zeolite (manufactured by Maeda Corporation)
Natural zeolite: Zeophyl CP (manufactured by New Tohoku Chemical Industry Co., Ltd., particle size 0.2 mm or less)

(Test 1)
2 L of contaminated water with low turbidity containing cesium as a radioactive substance was prepared (total concentration of radioactive cesium 137 and 134: 307.0 Bq / kg, cesium 137: 182.9 Bq / kg, cesium 134: 124.1 Bq / kg ). The flocculants A, C, and D were added to the contaminated water and stirred for 2 minutes, and then the contaminated water was allowed to stand for 5 minutes. At this time, the flocculant A is added so that the concentration of the flocculant is 0.2% by mass (2 kg / m ³ ), and for the flocculants C and D, the concentration of the flocculant is 0.1% by mass (1 kg). / M ³ ). The radiocesium concentration of the supernatant after standing was measured by gamma-ray spectroscopy with a germanium semiconductor detector. The results are shown in Table 4.

(Test 2)
2 L of contaminated water (same as Test 1) containing cesium as a radioactive substance and having less turbidity was prepared. 1 wt% (10 kg / m ³ ) of natural zeolite (Zeofil CP, manufactured by Shintohoku Chemical Co., Ltd., particle size of 0.2 mm or less) was added to the contaminated water as a radioactive cesium adsorbent, and the mixture was stirred for 5 minutes. Next, flocculants AD were added to the contaminated water, stirred for 2 minutes, and allowed to stand for 5 minutes. At this time, the flocculants A and B are added so that the flocculant concentration is 0.2% by mass (2 kg / m ³ ), and the flocculants C and D have a flocculant concentration of 0.1% by mass. It added so that it might become (1 kg / m < ³ >). The radiocesium concentration of the supernatant after standing was measured by gamma ray spectroscopy with a germanium semiconductor detector. The results are shown in Table 4.

From the results of Test 1 and Test 2, even when any of the flocculants A to D is used, the radioactivity of the supernatant liquid after adding the flocculant to the radioactive contaminated water and allowing to stand by adding natural zeolite. It was confirmed that the cesium concentration can be reduced. In the case of using the flocculant A in which the sedimentation rate of natural zeolite was slow and the supernatant was cloudy, radioactive cesium was detected from the supernatant. However, in the case of using the flocculants B to D in which the supernatant liquid became transparent, it was confirmed that the radioactive cesium concentration of the supernatant liquid could be reduced below the detection limit. From these facts, it was proved that it is important to agglomerate and precipitate until the supernatant liquid becomes transparent, since the adsorption effect of the radioactive substance by the natural zeolite can be verified. In addition, from the results of the flocculant D in Test 1, it has been clarified that the flocculant composition of the present invention containing natural zeolite as a constituent component has an adsorbing effect on a radioactive substance without adding an adsorbent.

Claims (7)

An anionic polymer flocculant;
A cationic polymer flocculant;
Natural zeolite,
Aluminum sulfate,
Containing
A flocculant composition for treating contaminated water, wherein 50% by mass or more of the aluminum sulfate has a particle size of 0.15 mm or less.   The flocculant composition according to claim 1, further comprising a carbonate.   The flocculant composition according to claim 2, wherein the carbonate includes sodium carbonate.   The flocculant composition according to claim 2 or 3, wherein the carbonate includes calcium carbonate.   The aggregating agent composition according to any one of claims 1 to 4, further comprising an organic acid.   The flocculant composition according to claim 5, wherein the organic acid includes at least one selected from the group consisting of malic acid, sulfamic acid, oxalic acid, citric acid, and tartaric acid. A method for treating contaminated water using the flocculant composition according to any one of claims 1 to 6,
A method for treating contaminated water, comprising the step of separating the contaminated water into a precipitate and a supernatant liquid by adding the flocculant composition to the contaminated water and stirring to agglomerate and precipitate the contaminant.

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