JP6387337B2 - Method for removing suspended matter in water using a flocculating / flocculating material for cross-linked suspension material, and flocculating / flocculating agent for suspended material for suspension material removal treatment - Google Patents

Description

  The present invention relates to a method for removing suspended substances in water using a cationic or amphoteric polymer flocculant having a cross-linked structure and the polymer flocculant. From waste water containing coarse suspended solids with a diameter of 50 μm or more and fine suspended solids less than 50 μm, the suspended solids are more effectively removed in a state where these suspended solids coexist. The present invention relates to a method for removing suspended substances in water that can be treated, and the polymer flocculant for use in the method.

  For example, waste water (raw water) from a steel mill or the like contains coarse suspended solids (hereinafter also referred to as coarse SS) having a particle size of 50 μm or more such as metal powder, coal / coke powder, and oil. However, these wastewaters are usually treated in advance by removing the coarse suspended substances in advance by a method such as sedimentation separation, and further treating the wastewater after the removal, whereby fine suspensions having a particle size of less than 50 μm are obtained. Turbid substances (hereinafter also referred to as fine SS) are removed to obtain treated water from which suspended substances have been removed.

  In contrast, the present inventors have already included the coarse SS and the fine SS by a very simple method such as adding a polymer flocculant to wastewater or the like in a turbulent flow state having a fast flow. Coarse SS and fine SS can be coagulated and settled together from raw raw water, and the coarse SS and fine SS can be removed at once, and the processing facilities can be simplified. A method for removing turbid substances has been proposed (see Patent Document 1 and Patent Document 2). Among them, it is preferable to use a polymer flocculant mainly composed of a cationic or amphoteric copolymer having a specific compound as a raw material monomer.

  According to the above prior art, the following effects can be obtained. For example, when separating and removing suspended substances in various wastewaters in which coarse SS and fine SS coexist, which occur in a steelworks, for example, a relatively small tank having an Over Flow Rate of 10 m / hr or more As a result, it is possible to settle SS more rapidly than in the case where the coarse SS and the fine SS are treated in the same process as in the case of the conventional technique, and the obtained treated water is separated from these suspended substances. The water quality can be as high as or better than that achieved by the conventional treatment method. More specifically, the coarse SS and the fine SS can be coagulated and settled faster than in the conventional technology by the same treatment, thereby reducing the total amount of the flocculant used than before. And the equipment can be greatly simplified. In addition to these, it is possible to reduce the recycling cost of the generated aggregated sediment, and to reduce the substances that promote the corrosion of piping mixed into the treated water due to the use of inorganic flocculants. Can be achieved. Furthermore, since the treated water obtained shows a clear water quality equivalent to or higher than that achieved by the conventional treatment method, it can be circulated as it is, and the generated aggregated sedimented sediment is separated from the water. There is also an advantage that it is easy to handle and easy to handle.

  On the other hand, cationic polymers have been attracting attention for their usefulness as dehydrating agents for a long time, and they have been used as sludge dehydrating agents. In order to improve dehydrating properties, cationic polymers can also be modified. (See Patent Documents 3 to 5).

JP 2014-108394 A JP 2014-133229 A Japanese Patent Publication No. 7-71678 Japanese Patent No. 2777732 Japanese Patent No. 5692910

  As described above, the above-described conventional technology developed by the present inventors coagulates and settles the coarse SS and the fine SS together from the raw water containing the coarse SS and the fine SS, thereby obtaining the coarse SS and the fine SS. It is an epoch-making thing that can be removed at once. However, as described above, the treatment of wastewater generated at a steel mill or the like is performed by removing coarse SS in advance by a method such as sedimentation separation and further treating the wastewater after removal to remove fine SS. A treatment flow has been established in which treated water free from turbid substances is obtained, and until now, coarse SS and fine SS have not been coagulated and settled together with actual wastewater. For this reason, when applying the method of coagulating and sedimenting coarse SS and fine SS together with actual wastewater, it is important to establish a treatment flow that can stably achieve higher effects. Specifically, if the conditions that allow the SS to be removed more efficiently and effectively when the coarse SS and the fine SS are coagulated and settled together, the above-described conventional technology can be found. Can be a more effective SS processing means.

  Therefore, the object of the present invention is more efficient when the coarse SS and fine SS in water that have already been proposed by the present inventors are coagulated and settled together, and these SS are removed together. The goal is to provide a method of treatment, and ultimately improve the efficiency of treatment, speed of treatment, and secondary treatment of coagulated sediment precipitates, which are important when applied to actual wastewater. It is an object of the present invention to provide a method for removing suspended substances in water that can achieve the above.

（上記式（１）及び（２）中の、Ｒ₁は、Ｈ又はＣＨ₃、Ｒ₂又はＲ₃は、それぞれ独立にＣＨ₃又はＣ₂Ｈ₅を表し、Ｒ₄は、Ｈ、ＣＨ₃又はＣ₂Ｈ₅のいずれかを表す。Ｘ^-は、アニオン性対イオンを表す。） The above object is achieved by the present invention described below. That is, the present invention adds a polymer flocculant to waste water or water taken in a state where a coarse suspended substance and a fine suspended substance coexist, and these suspended substances are subjected to the same treatment. A method for removing suspended matter in water that is coagulated and settled and removed together, wherein the coarse suspended substance has a particle size of at least 50 μm, and includes at least the coarse suspended substance and the fine substance. When the suspension material is coagulated and settled by the same treatment by causing a state in which the polymer flocculant coexists in turbulent water coexisting with a suspended solid, , 0.5 to 300 ppm by mass relative to the total amount of raw material monomers containing 5 mol% or more of any one or both of the monomers represented by the following general formula (1) and the following general formula (2) as essential components Polymerization in the presence of crosslinkable monomers A cross-linked cationic or amphoteric cross-linked water-soluble polymer is used, and the cross-linked water-soluble polymer is added to the degree of cross-linking in pure water and diluted 200 times with pure water. By measuring the viscosity of the aqueous solution by adding the aqueous solution viscosity in 4% saline solution and dividing by 80% diluted aqueous solution in 4% saline solution. Provided is a method for removing suspended substances in water, characterized in that, when expressed by the obtained value, the value is 5 or more and 200 or less.

(In the above formulas (1) and (2), R ₁ represents H or CH ₃ , R ₂ or R ₃ each independently represents CH ₃ or C ₂ H ₅ , and R ₄ represents H, CH ₃ Or C ₂ H ₅ , X ⁻ represents an anionic counter ion.)

  The following is mentioned as a preferable form of the removal processing method of the suspended matter in water of this invention. The crosslinkable monomer is 0.5 to 50 ppm by mass with respect to the total amount of raw material monomers; the abundance of the coarse suspended substance in water is 130 mg / L or more; The amount of suspended solids is 130 mg / L or more, and the ratio of the coarse suspended solid concentration to the fine suspended solid concentration (rough / fine) is 3 or more in terms of its mass ratio; Water is wastewater generated in a steelworks, and the position where the polymer flocculant is added to the wastewater generates wastewater in which the coarse suspended substance and the fine suspended substance coexist. Any point from the point to the vicinity of the entrance of the water treatment facility, and the waste water at the point is in a turbulent state at a flow velocity of 0.5 m / second or more; the water is coarse in the water Preliminarily coarse in water containing almost no suspended matter It is water in which a suspended substance is added so that the amount of the coarse suspended substance is 130 mg / L or more and the coarse suspended substance and the fine suspended substance coexist. Can be mentioned.

（上記式（１）及び（２）中の、Ｒ₁は、Ｈ又はＣＨ₃、Ｒ₂又はＲ₃は、それぞれ独立にＣＨ₃又はＣ₂Ｈ₅を表し、Ｒ₄は、Ｈ、ＣＨ₃又はＣ₂Ｈ₅のいずれかを表す。Ｘ^-は、アニオン性対イオンを表す。） As another embodiment of the present invention, turbulent waste water or water intake in which coarse suspended substances having a particle diameter of 50 μm or more and fine suspended substances having a particle diameter of less than 50 μm coexist are provided. A polymer flocculant for use in a method for removing suspended solids in water by adding a polymeric flocculant to the water and removing the suspended solids by coagulation sedimentation by the same treatment, 0.5 to 300 ppm by mass with respect to the total amount of raw material monomers containing 5 mol% or more with either one or both of the monomers represented by the following general formula (1) and the following general formula (2) as essential components A cationic or amphoteric crosslinked water-soluble polymer having a crosslinked structure obtained by polymerization in the presence of a crosslinking monomer, and the degree of crosslinking of the crosslinked water-soluble polymer in pure water Aqueous solution added and diluted 200 times with pure water The value obtained by measuring the viscosity of the aqueous solution, divided by the viscosity of the aqueous salt solution when the aqueous solution was added to 4% saline and diluted 80 times with 4% saline. When expressed, the present invention provides a polymer flocculant for suspension substance removal treatment, wherein the value is 5 or more and 200 or less.

(In the above formulas (1) and (2), R ₁ represents H or CH ₃ , R ₂ or R ₃ each independently represents CH ₃ or C ₂ H ₅ , and R ₄ represents H, CH ₃ Or C ₂ H ₅ , X ⁻ represents an anionic counter ion.)

  A preferred form of the polymer flocculant for the suspended matter removal treatment of the present invention is that the crosslinkable monomer is 0.5 to 50 ppm by mass with respect to the total amount of raw material monomers.

  According to the present invention, when the present inventors have already proposed a method of coagulating and sedimenting coarse SS and fine SS in water together and removing these SS together, the processing is performed more efficiently. It is possible to provide a method, and ultimately, it is easier to improve the processing efficiency, speed of processing, and secondary treatment of coagulated sediment precipitate, which are important when applied to actual wastewater. A method for removing suspended matter in water is provided.

It is a graph which shows the relationship between the addition amount of a polymer flocculant, the amount of coarse SS in wastewater, and SS in treated water when polymer flocculants having different structures are used.

  Hereinafter, the present invention will be described in more detail with reference to preferred embodiments. In order to make it possible to apply the above-described technology already proposed by the present inventors to actual wastewater and to perform more efficient and more reliable treatment, the present inventors have not performed at all. It was recognized that a more detailed study was necessary because of the unclear processing method. Specifically, based on the above recognition, it was recognized that the following points should be considered during the study.

  In the method already proposed by the present inventors, the coarse SS is not separated in advance, and the cationic or amphoteric polymer flocculant (raw water) containing the coarse SS and the fine SS is contained in the waste water (raw water). In the process, the polymer flocculant is added to the wastewater in a turbulent state, and coarse SS, fine SS, and polymer flocculence are added. It is necessary for the agent to coexist in a turbulent state. The present inventors have obtained the following knowledge in the process of studying these requirements. First, regarding the addition amount of the polymer flocculant, it was found that the treatment amount does not necessarily improve when the addition amount is large, and that the SS processability tends to deteriorate when the addition amount is excessive. Therefore, finding the upper limit of the amount of the polymer flocculant to be added that can reliably obtain the high effect of the present invention is extremely useful for reliably performing good treatment.

  As described above, in the present invention, it is necessary to add the polymer flocculant at least to the wastewater in a turbulent state, and in order to perform a better flocculation sedimentation / precipitation treatment, the speed is high. It is preferable to carry out in wastewater in a strong turbulent state. For this reason, for example, when there is no place in a facility for treating wastewater that is in a strong turbulent state, it is necessary to take measures such as adding an agitator. In contrast, the present inventors have found that depending on the type of the polymer flocculant, a high effect may be observed even in a relatively gentle turbulent state. In other words, in the state where coarse SS, fine SS and polymer flocculant coexist, it has been found that there is a kind of polymer flocculant which can provide excellent agglomeration sedimentation even with a weak stirring force and a short stirring time. . This means that if such a polymer flocculant is used, the selection range of the addition position of the polymer flocculant in the facility for treating wastewater is expanded. This is extremely useful because there is a possibility that measures such as adding a stirrer can be eliminated so that a strong turbulent state can be obtained.

  Furthermore, as described above, the precipitate that has been aggregated and settled by coexisting coarse SS, fine SS, and polymer flocculant in a turbulent state by the treatment method of the present invention is handled with good water separation. It becomes easy. As a result of further study on this point, the present inventors have found that some precipitates obtained by coagulation sedimentation have characteristics that are difficult to redisperse and that facilitate subsequent processing. It was found that the difference in characteristics was caused by the type of polymer flocculant used.

  More specifically, when a specific polymer flocculant having a cross-linked structure defined in the present invention described below is used for the treatment of SS, the polymer flocculant can be used even with a weak stirring force or a short stirring time. Excellent cohesive sedimentation properties for the coexisting coarse SS and fine SS, and the remarkable effect of the present invention can be obtained even in a relatively mild turbulent state. It was also found that the precipitate obtained by agglomeration and sedimentation by using the above polymer flocculant is difficult to redisperse and can be easily processed thereafter.

（上記式（１）及び（２）中の、Ｒ₁は、Ｈ又はＣＨ₃、Ｒ₂又はＲ₃は、それぞれ独立にＣＨ₃又はＣ₂Ｈ₅を表し、Ｒ₄は、Ｈ、ＣＨ₃又はＣ₂Ｈ₅のいずれかを表す。Ｘ^-は、アニオン性対イオンを表す。） The specific polymer flocculant having a crosslinked structure that characterizes the present invention contains 5 mol% or more of any one or both of the monomers represented by the following general formula (1) and the following general formula (2) as essential components. A cationic or amphoteric cross-linked water-soluble polymer having a cross-linked structure obtained by polymerization in the presence of 0.5 to 300 ppm of a cross-linkable monomer by mass with respect to the raw material monomer to be contained, and The cross-linking degree of the cross-linking water-soluble polymer is added to pure water, and the aqueous solution viscosity when diluted to 200 times with pure water is added to 4% saline. When expressed as a value obtained by measuring the viscosity of the aqueous solution divided by the viscosity of the aqueous salt solution when the aqueous solution is diluted 80 times, the value is 5 or more and 200 or less.

(In the above formulas (1) and (2), R ₁ represents H or CH ₃ , R ₂ or R ₃ each independently represents CH ₃ or C ₂ H ₅ , and R ₄ represents H, CH ₃ Or C ₂ H ₅ , X ⁻ represents an anionic counter ion.)

  As a more preferable thing of the bridge | crosslinking type polymer flocculent used by this invention, what the said crosslinkable monomer is 0.5-50 ppm by mass with respect to the total amount of a raw material monomer is mentioned. If the amount is less than 0.5 ppm, the blending amount is too small and it cannot be regarded as being surely copolymerized (having a crosslinked structure). The crosslinkable polymer flocculent that characterizes the present invention can be easily produced by the method described in Patent Document 5 (Japanese Patent No. 5692910) cited as the prior art. Examples of commercially available products include NCS-1530, NCS-1540, NCS-1649 (all trade names) manufactured by Nippon Steel & Sumikin Environment Co., Ltd., and any of them can be used.

  Typical examples of the monomer represented by the formula (1) include acryloyloxyethyltrimethylammonium chloride, hydrochloride of dimethylaminoethyl acrylate, and the like. A typical example of the monomer represented by the formula (2) is acryloyloxyethyldimethylbenzylammonium chloride. Examples of other monomers copolymerizable with these monomers include (meth) acrylamide, N-methyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide and the like.

  The crosslinkable monomer used in the present invention is also referred to as a structural modifier because it is added for the purpose of modifying the molecular structure of the polymer, and the following are used. For example, N, N-methylenebis (meth) acrylamide, triallylamine, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate , Polyethylene glycol di (meth) acrylate, N-vinyl (meth) acrylamide, N-methylallylacrylamide, glycidyl acrylate, polyethylene glycol diglycidyl ether, acrolein, glyoxal, vinyltrimethoxysilane, etc. As a crosslinking agent, a water-soluble polyvinyl compound is more preferable, and the most preferable is N, N-methylenebis (meth) acrylamide. Also, using a chain transfer agent such as sodium formate and isopropyl alcohol in combination is also effective as a method for adjusting the cross-linking property.

At present, there is no general method for displaying the degree of crosslinking of the crosslinkable polymer. In the present invention, in accordance with the method described in Patent Document 5 (Japanese Patent No. 5629910), a method of expressing the degree of crosslinking by measuring the viscosity of the aqueous solution was adopted. Specifically, as defined in the present invention, in the present invention, the aqueous solution viscosity when the water-soluble polymer is added to pure water and diluted 200-fold with pure water is defined as AQV, When a water-soluble polymer is added to 4% saline and the aqueous solution is diluted 80-fold with 4% saline to give an aqueous solution with a salt solution viscosity of SLV, the degree of cross-linking satisfies the following formula: A water-soluble polymer is used as a flocculant.
5 ≦ AQV / SLV ≦ 200 (at 25 ° C.)

  As described above, the specific polymer flocculant having the above-mentioned cross-linking structure defined in the present invention tends to deteriorate SS processability when the addition amount is excessive. According to the study by the present inventors, this point is the same for the linear polymer flocculant having no cross-linked structure.

  In addition, as a result of detailed investigations by the present inventors, it is possible to suppress the addition amount of the polymer flocculant by using the specific polymer flocculant having the above-described cross-linking structure defined in the present invention. I found out that

  Further, according to the detailed examination by the present inventors, the coarse SS, the fine SS, and the polymer flocculant coexist in a turbulent state as requirements for performing good and reliable treatment with the treatment method of the present invention. Thus, it is effective to define the coexistence state of these substances when the coarse SS and the fine SS are coagulated and settled by the same treatment. At that time, it is particularly effective to define the abundance of coarse SS in the wastewater to be treated. In this case, when a linear polymer flocculant is used, it is effective that the abundance of coarse SS is 250 mg / L or more, whereas a cross-linked polymer flocculant is used. It was found that the abundance of coarse SS can be reduced to 130 mg / L or more. This means that more effective treatment becomes possible by changing the type of the polymer flocculant used according to the properties of the wastewater to be treated.

  Next, the present invention will be described more specifically with reference to examples and comparative examples.

<Simulated wastewater>
For the examination test, each simulated wastewater in which coarse SS and fine SS are mixed in the respective abundances was prepared as follows. Specifically, in tap water, kaolin having a median particle size distribution of about 2 μm is contained as fine SS as about 100 mg / L, and silica sand having an average particle size of about 150 μm is used as coarse SS. Simulated wastewater was obtained by adjusting the concentration of coarse SS to be as follows. That is, the above-mentioned silica sand was used so that the abundance of coarse SS in the simulated waste water was 500 mg / L, 1000 mg / L, 2000 mg / L, 5000 mg / L, 10000 mg / L, and 20000 mg / L, respectively.

<Polymer flocculant>
As a comparative polymer flocculant, acrylamide / [2- (acryloyl) derived from raw material monomers each containing 20 mol% each of two types of monomers represented by the general formulas (1) and (2) as essential components Oxy) ethyl] benzyldimethylammonium chloride / [2- (acryloyloxy) ethyl] trimethylammonium chloride copolymer (molar ratio = 60/20/20) is used as a cationic water-soluble polymer. It was. Its weight average molecular weight is 3 million, and the cation colloid equivalent at pH 7 is 2.0 meq / g. About the obtained water-soluble polymer, the value calculated | required by the method of obtaining the crosslinking degree by the viscosity measurement of aqueous solution mentioned later was 4. This water-soluble polymer is called a linear polymer flocculant.

  In addition, a crosslinkable water-soluble polymer can be obtained by blending methylenebisacrylamide as a crosslinkable monomer with the above raw material monomer so as to have a mass of 30 ppm with respect to the total amount of the raw material monomer. It was. The obtained cross-linked water-soluble polymer had a degree of cross-linking of 48 expressed by a value obtained by measuring the viscosity of an aqueous solution. The specific measurement and calculation of the degree of crosslinking were performed as follows. The obtained water-soluble polymer was added to pure water, and the viscosity of the aqueous solution was measured when it was diluted 200-fold with pure water. The degree of cross-linking is obtained by dividing the molecule by the measured value obtained by measuring the viscosity of the salt aqueous solution when the molecule is added to 4% saline and diluted to 80 times with 4% saline. It was. In the present invention, a water-soluble polymer having a value obtained above of 5 or more and 200 or less was used as a crosslinkable polymer flocculant.

(Examination of addition amount of polymer flocculant 1-when coarse SS amount in wastewater is 500 to 20000 mg / L)
Using each of the simulated wastewaters with different abundance of coarse SS prepared earlier, the linear polymer flocculant obtained above and the cross-linked polymer flocculant were used, respectively, and addition of the polymer flocculant The amount of the polymer flocculant when coexisting with the coarse SS and the fine SS is 0.25 mg / L, 0.5 mg / L, and 0.75 mg / L (only in the case of the linear type). Then, the coagulation sedimentation treatment was performed. Specifically, the simulated wastewater in the vessel is turbulently stirred with a stirrer, a polymer flocculant is added to the wastewater in this state, and then left to stand, and the resulting supernatant water (treatment) Coarse SS in water) was measured. At this time, the conditions for stirring and standing were the same. Table 1 shows the results obtained. FIG. 1 is a graph showing the results when the concentration of the added polymer flocculant is 0.25 mg / L.

  As shown in Table 1 and FIG. 1, it was confirmed that the use of a cross-linked polymer flocculant can reduce the amount of the drug added compared to the case of using a linear polymer flocculant. . Furthermore, it can be seen from Table 1 that when any polymer flocculant is used, when it is added excessively, the properties of the resulting treated water tend to deteriorate.

(Study on addition amount of polymer flocculant 2-in case of actual waste water with coarse SS amount of 13-2000 mg / L)
Hot rolled wastewaters with different abundances of SS were prepared. For reference, the ratio of coarse SS to fine SS (coarse SS / fine SS) is shown in the table. For these wastewaters, the previously obtained linear polymer flocculant and cross-linked polymer flocculant are used, respectively, and the addition amount of the polymer flocculant is allowed to coexist with coarse SS and fine SS. In this case, the concentration of the polymer flocculant was adjusted to 0.5 mg / L, 0.75 mg / L, and 1 mg / L, respectively, and the aggregation and sedimentation treatment was performed. The specific processing method was the same as that performed in the previous study. Table 2 shows the results obtained. The target coarse SS in the treated water is 20 mg / L.

  As shown in Table 2, in addition to using a cross-linked polymer flocculant, the amount of addition can be reduced as compared with the case of using a linear polymer flocculant. It was found that if the coagulant concentration is 1 mg / L, a good coagulation sedimentation treatment can be performed even with wastewater having a coarse SS amount of 130 mg / L. On the other hand, when a conventional linear polymer flocculant is used, if the polymer flocculant concentration is 1 mg / L, a coarse SS amount of 250 mg / L or more is required. Also, it was confirmed that there is an advantage by using a cross-linked polymer flocculant.

(Examination of the difference in coagulation sedimentation when using cross-linked and linear polymer flocculants)
Using the simulated wastewater containing 2000 mg / L of the coarse SS prepared previously, the simulated wastewater in the vessel is turbulently stirred with a stirrer, and the polymer flocculant is added to the wastewater in this state by 0.00. 5 mg / L was added, and then allowed to stand, and SS (mg / L) in the obtained supernatant water (treated water) was measured. At that time, the turbulent flow state of the simulated wastewater when the polymer flocculant was added was changed by changing the stirring conditions by the stirrer. The results of this test are shown in Table 3.

  In the treatment method of the present invention, it is important that the water to be treated is in a turbulent state of a certain level or more. By adding a polymer flocculant to the waste water in such a state, The remarkable effect of the invention is obtained. On the other hand, as shown in Table 3, the case of using the cross-linked polymer flocculant is weaker in stirring force and the time of stirring than the case of using the linear polymer flocculant. It was found that the coagulation sedimentation reaction was completed. As a result, in the conventional method using a linear polymer flocculant in facilities with weak turbulent flow, there were cases where measures such as adding an agitator were necessary. It is expected that this will not be necessary. In addition, in the conventional method using a linear polymer flocculant, the addition position of the polymer was preferably added upstream of the equipment for precipitation. It is expected that the degree of turbulence is weaker than this, for example, it can be set in the vicinity of flowing into the facility for precipitation. For this reason, in the case of the treatment method of the present invention, the degree of freedom in selecting the position where the polymer flocculant is added is increased.

(Examination of the difference in properties of aggregated precipitates when cross-linked and linear polymer flocculants are used)
Based on tap water, the fine SS concentration is adjusted to 100 mg / L using kaolin having a median particle size distribution of 2 μm, and the coarse SS concentration is set using silica sand having an average particle size of about 150 μm. A simulated wastewater was prepared by adjusting to 2000 mg / L. Then, while this simulated wastewater was stirred to be in a turbulent state, the same cross-linked polymer flocculant and linear polymer flocculant as previously used were combined with the polymer flocculant in the wastewater. The agent was added to a concentration of 1.0 mg / L, and the following series of treatments were performed. That is, the mixture was stirred for 1 minute in the presence of the polymer flocculant, and then allowed to stand to obtain a precipitate, and SS (mg / L) in the supernatant water (treated water) was measured. Thereafter, in the same manner as previously performed, the mixture was stirred again for 15 minutes, and then left to stand to obtain a precipitate again, and SS (mg / L) in the supernatant water (treated water) was measured again. Table 4 shows the results obtained.

  As can be seen from the results shown in Table 4, the precipitate formed by agglomeration and sedimentation by the removal treatment method of the present invention is redispersed as compared with the case of using a linear polymer flocculant. A new fact was confirmed that it was a strong agglomerate that was again prevented from returning to suspended matter. This fact means that a very useful new effect can be obtained when an actual wastewater treatment is performed by using a cross-linked polymer flocculant as described below. In the present invention, coarse SS and fine SS agglomerated and sedimented together by a specific polymer flocculant are sent to a sludge storage tank by a submersible pump, or a bucket called a clamshell type. It is dredged by a crane with a sword and transported to a sludge storage tank. In the course of this operation, if the fine SS is peeled off from the coarse SS constituting the agglomeration / precipitate, the fine SS is contained in the supernatant water separated in the sludge storage tank and becomes turbid. Necessary. On the other hand, when the crosslinkable polymer flocculant specified in the present invention is used, the aggregate and precipitate of the coarse SS and the fine SS have a strong bonding force, and the fine SS is peeled off from the coarse SS. Is not separated from the coarse SS, so that it is not necessary to process the re-dispersed fine SS again.

Claims (7)

The agglomeration / sedimentation agent for the suspended solids is added to the water such as waste water or water intake in which coarse suspended solids and fine suspended solids coexist, and these suspended solids are subjected to the same treatment. A method for removing suspended matter in water that is coagulated and settled and removed together,
The coarse suspended substance has at least a particle size of 50 μm or more, and contains at least one of metal powder, coal powder, or coke powder having a particle size of 50 μm or more, and the fine suspended substance includes: Disturbance in which the coarse suspended substance and the fine suspended substance coexist in a state where the particle size is less than 50 μm and at least the abundance of the coarse suspended substance is 130 mg / L or more. When the coagulation / sedimentation agent of the suspended substance coexists in the flowing water, and the suspended substance is coagulated and settled by the same treatment,
As a coagulation / sedimentation agent for the suspended matter
0.5 to 300 ppm by mass with respect to the total amount of raw material monomers containing 5 mol% or more with either one or both of the monomers represented by the following general formula (1) and the following general formula (2) as essential components A cationic or amphoteric crosslinked water-soluble polymer having a crosslinked structure obtained by polymerization in the presence of a crosslinking monomer is used, and the crosslinked water-soluble polymer has a degree of crosslinking of pure water. The aqueous solution viscosity when added to the inside and diluted to 200 times with pure water is added to the 4% saline solution, and the salt when the aqueous solution is diluted 80 times with 4% saline solution. A method for removing suspended substances in water, characterized in that when expressed by a value obtained by measuring the viscosity of an aqueous solution divided by the viscosity of an aqueous solution, the value is 5 or more and 200 or less.

(In the above formulas (1) and (2), R ₁ represents H or CH ₃ , R ₂ or R ₃ each independently represents CH ₃ or C ₂ H ₅ , and R ₄ represents H, CH ₃ Or C ₂ H ₅ , X ⁻ represents an anionic counter ion.)   The method for removing suspended substances in water according to claim 1, wherein the crosslinkable monomer is 0.5 to 50 ppm by mass with respect to the total amount of raw material monomers.   The abundance of the coarse suspended substance is 130 mg / L or more, and the ratio of the coarse suspended substance concentration to the fine suspended substance concentration (rough / fine) is 3 or more by mass ratio. The method for removing suspended substances in water according to claim 1 or 2. The water is wastewater generated in a steelworks;
The position at which the suspending material coagulation / sedimentation agent is added to the wastewater is located near the entrance of the water treatment facility from the point where the wastewater where the coarse suspended material and the fine suspended material coexist is generated. The suspended matter in water according to any one of claims 1 to 3 , wherein the wastewater at any point is in a turbulent state at a flow velocity of 0.5 m / sec or more. Removal processing method. When the water is water having an abundance of the coarse suspended substance in water of less than 130 mg / L and hardly containing the coarse suspended substance in water, it functions as the coarse suspended substance in advance. Silica sand is added so that the amount of the coarse suspended substance is 130 mg / L or more, and the water is a state in which the coarse suspended substance and the fine suspended substance coexist. Item 4. The method for removing suspended substances in water according to any one of Items 1 to 3 . A coarse suspended substance containing at least one of metal powder, coal powder or coke powder having a particle diameter of 50 μm or more, or silica sand functioning as the added coarse suspended substance, and a fine particle diameter less than 50 μm Suspended material coagulation / sedimentation agent is added to water such as turbulent waste water and water intake that coexist with various suspended materials, and these suspended materials are coagulated and settled by the same treatment and removed together. A suspension substance agglomeration / sedimentation agent for use in a method for removing suspended matter in water,
0.5 to 300 ppm by mass with respect to the total amount of raw material monomers containing 5 mol% or more with either one or both of the monomers represented by the following general formula (1) and the following general formula (2) as essential components A cationic or amphoteric crosslinked water-soluble polymer having a crosslinked structure obtained by polymerization in the presence of a crosslinking monomer, and the degree of crosslinking of the crosslinked water-soluble polymer in pure water Addition and viscosity of aqueous solution when diluted to 200 times with pure water is added to 4% saline and then diluted to 80 times with 4% saline to obtain aqueous solution viscosity of salt solution A suspended substance aggregating / sedimenting agent for suspended substance removal treatment, wherein the value is 5 or more and 200 or less when expressed by a value obtained by measuring the viscosity of an aqueous solution divided by 1.

(In the above formulas (1) and (2), R ₁ represents H or CH ₃ , R ₂ or R ₃ each independently represents CH ₃ or C ₂ H ₅ , and R ₄ represents H, CH ₃ Or C ₂ H ₅ , X ⁻ represents an anionic counter ion.) The flocculating substance coagulation / sedimentation agent for suspended substance removal treatment according to claim 6 , wherein the crosslinkable monomer is 0.5 to 50 ppm by mass with respect to the total amount of raw material monomers.

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