JP6374352B2 - Suspended matter polymer coagulation / sedimentation agent and suspended matter removal method - Google Patents

Description

  The present invention relates to a cationic or amphoteric polymer flocculant, and more specifically, for example, from wastewater containing coarse suspended substances such as metal powder and oil components having a particle size of 50 μm or more generated in an iron mill or the like. The present invention relates to a useful polymer flocculant that can remove suspended substances all at once in a state of containing coarse suspended substances.

  For example, waste water from a steel factory 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. The treatment of these wastewaters is performed by removing the above-mentioned coarse suspended solids in advance by a method such as sedimentation separation, and further treating the wastewater after the removal, whereby fine suspended solids having a particle size of less than 50 μm (hereinafter referred to as “wastewater”). , Also referred to as fine SS) to obtain treated water free of suspended matter.

  In the process of removing the fine SS described above, various flocculants are usually used, and the fine SS is coarsened by agglomeration to facilitate the removal process from the wastewater. Conventionally, various investigations have been made on the flocculant used at that time, and various kinds of flocculants are used in combination depending on the properties of the target wastewater. For example, if the target wastewater is oil-containing wastewater containing a large amount of suspended solids in industries such as steel, petrochemical, food processing, and automobile industry, polyaluminum chloride (PAC), sulfate band, iron salt, etc. The treatment is performed by appropriately adding a flocculant such as an inorganic flocculant, an organic cation flocculant, an organic flocculant such as an organic anionic flocculant, and the like. At that time, since various kinds of suspended solids are contained in the above-mentioned wastewater, a plurality of types of flocculants are selected from a large number of inorganic flocculants and organic flocculants (polymer flocculants). It is common practice to select and use these in combination to sequentially remove the suspended matter.

  More specifically, for example, in Patent Document 1, a specific cationic water solution obtained by polymerizing a monomer mixture containing at least 5 mol% of a specific cationic monomer in oil-containing wastewater. A method has been proposed in which an anionic water-soluble polymer is added and treated after the addition of a functional polymer (see Patent Document 1). Moreover, the proposal about using together an inorganic flocculant and a cationic dispersion type | mold (co) polymer is made (refer patent document 2), According to the said literature, by doing in this way, more It is said that the concentration of oil and suspended substances in oil-containing wastewater can be efficiently reduced, and the amount of inorganic flocculant used can be suppressed.

  Moreover, the cationic polymer as disclosed above has been attracting attention as a dehydrating agent for a long time, and is used as a dewatering agent for sludge (see Patent Documents 3 and 4). ).

JP 2004-255349 A JP 2008-006382 A Japanese Patent Publication No. 7-71678 Japanese Patent No. 2777732

  However, the development of polymer flocculants so far is aimed at more efficiently dewatering sludge and more efficiently removing fine SS in waste water after removing coarse SS. It was limited to what was. For example, if a polymer flocculant is used to remove suspended solids in wastewater from a steel mill or the like that contains coarse SS such as metal powder, coal / coke powder, or oil, the coarse SS should be It is necessary to perform the removal treatment, and the use of the polymer flocculant does not change at all in terms of removal of the fine SS. On the other hand, particularly in steelworks, the amount of wastewater to be treated is large and the types of wastewater are large, so the treatment equipment for removing suspended solids from wastewater is huge. If the equipment can be simplified and the amount of the flocculant used can be reduced, the economic effect is extremely large.

  There are various types of wastewater generated from steelworks. For example, a large amount of cooling water is required in the casting process and the hot rolling process, and the cooling water after use includes a large amount of suspended substances such as iron powder and oil. For this reason, the wastewater is reused (circulated) as cooling water. In this case, it is necessary to remove the suspended substances in the cooling wastewater to a level that can be used as cooling water. For example, in the wastewater generated in the hot rolling process, in addition to fine suspended matter (fine SS) having a particle size of less than 50 μm of the order of several μm to several tens of μm made of iron powder, oil, etc. In some cases, a coarse suspended substance (coarse SS) having a particle size of 50 μm or more, and in some cases, about 1000 μm is included. For this reason, as described above, when the suspended solids are removed from the cooling wastewater, the coarse SS is removed in advance by a method such as sedimentation separation, and even if a large particle is contained, the particle size is reduced. By making waste water in the state of fine SS less than 50 μm, and then removing it by adding a flocculant, it is possible to reduce the amount of flocculant to be used, and to improve the treatment efficiency by the flocculant . In addition, when removing suspended substances, it is usual to use a plurality of types of flocculants such as a combination of an inorganic flocculant and a polymer flocculant.

  In contrast to the above-described current state of the prior art, the present inventors coexisted (coexisted) coarse SS and fine SS with a reduced use amount without increasing the use amount of the conventional flocculant. These suspended solids can be easily removed from waste water in the same state by the same treatment, and if better treated water can be obtained, the treatment equipment can be greatly reduced. We came to realize that extremely economical processing would be possible. Further, if the aggregated and settled precipitate can be easily processed thereafter, the secondary treatment of the settled / precipitate is facilitated, which is further useful.

  Therefore, the object of the present invention is not to increase the amount of use, and does not necessarily require the use of an inorganic flocculant. From the wastewater in which coarse SS and fine SS coexist, these suspended substances are obtained. Provides a polymer flocculant that can be removed quickly and easily by the same treatment, and that the treated water has a clear property without turbidity, and facilitates the treatment of the coagulated sediment. There is to do.

（上記式中の、Ｒ₁、Ｒ₂は、それぞれ独立にＣＨ₃又はＣ₂Ｈ₅を表し、Ｒ₃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, this invention is used when removing these suspended solids from the wastewater in the state where coarse suspended solids and fine suspended solids coexist as the first invention by the same treatment. Cationic property derived from a raw material monomer 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. Alternatively, a value obtained by multiplying the weight average molecular weight (Mw) of the copolymer by the square of the cation colloid equivalent (CE) at pH 7 by 1 million, which is mainly composed of an amphoteric copolymer. A polymer flocculant characterized by having an N value of 5 to 60 when N is N.

(In the above formula, R ₁ and R ₂ each independently represent CH ₃ or C ₂ H ₅ , and R ₃ represents either H, CH ₃ or C ₂ H _5. X ⁻ represents an anion. Represents sex counter ion.)

  The above-described polymer flocculant of the present invention further has a weight average molecular weight of 2 million to 13 million and a cation colloid equivalent at pH 7 of 0.7 to 4.1 meq / g; Is 4 to 13 million and the cation colloid equivalent at pH 7 is 1.1 to 3.5 meq / g.

（上記式中の、Ｒ₁、Ｒ₂は、それぞれ独立にＣＨ₃又はＣ₂Ｈ₅を表し、Ｒ₃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 can be achieved more stably and effectively by the following present invention. That is, this invention is used when removing these suspended solids from the wastewater in the state where coarse suspended solids and fine suspended solids coexist as the second invention by the same treatment. Cationic property derived from a raw material monomer 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. Alternatively, a value obtained by multiplying the weight average molecular weight (Mw) of the copolymer by the square of the cation colloid equivalent (CE) at pH 7 by 1 million, which is mainly composed of an amphoteric copolymer. N is 5 to 60, and the value obtained by dividing the weight average molecular weight (Mw) of the copolymer by the cation colloid equivalent (CE) at pH 7 is 1 million. The divided value is L If, to provide a polymeric flocculant, wherein the L value is 1.5 or more.

(In the above formula, R ₁ and R ₂ each independently represent CH ₃ or C ₂ H ₅ , and R ₃ represents either H, CH ₃ or C ₂ H _5. X ⁻ represents an anion. Represents sex counter ion.)

  The polymer flocculant of the present invention described above preferably further has a weight average molecular weight of 5 million to 11 million and a cation colloid equivalent at pH 7 of 1.2 to 3.4 meq / g.

  Any of the polymer flocculants of the present invention described above preferably further has the following constitution. The coarse suspended substance has at least a particle diameter of 50 μm or more, and the fine suspended substance has a particle diameter of less than 50 μm; when the suspended substance is removed by the same treatment The amount added to the treated wastewater is 0.5 mg / L or more; the wastewater is produced in a steel factory, and the suspended substance in the wastewater contains metal powder and oil. .

  According to the present invention, these suspended substances are made the same from waste water in a state where coarse SS and fine SS coexist without increasing the amount of use, without using in combination with an inorganic flocculant. A polymer flocculant that can be easily agglomerated and easily removed by treatment, and that the treated water has a clear property that does not become turbid when visually observed, and that facilitates the treatment of agglomerated sediment. Can be provided. As a result, the use of the polymer flocculant of the present invention eliminates the need for a part of a huge processing facility for removing suspended substances contained in cooling wastewater or the like that has been conventionally required in steel mills. In addition, the amount of the flocculant used can be reduced, and the aggregated and settled precipitate can be handled easily and processed very easily, and the economic effects brought about by these are extremely large. It is extremely useful industrially.

It is a graph which shows the difference in the state of aggregation / sedimentation of a suspended substance when various polymer flocculants having different properties are used. It is a graph which shows that aggregation and sedimentation of a suspended substance are performed favorably when the polymer flocculant of the range prescribed | regulated by 1st invention of this invention is used. It is a graph which shows that aggregation and sedimentation of a suspended substance are performed favorably when the polymer flocculant of the range prescribed | regulated by 2nd invention of this invention is used.

  Hereinafter, the present invention will be described in more detail with reference to preferred embodiments. In order to solve the above-described problems in the prior art, the present inventors rapidly agglomerate and condense these SSs when simultaneously treating wastewater in a state where coarse SS and fine SS coexist. As a result of intensive investigations to find a polymer flocculant capable of rapidly aggregating sedimentation and clarifying treated water, the present invention has been achieved. The polymer flocculant provided by the present invention comprises a cationic or amphoteric copolymer derived from a raw material monomer having a specific structure, which will be described later, as a main component, and the weight average molecular weight of the copolymer. N value or N value and L value defined by (Mw) and its cation colloid equivalent (CE) at pH 7 must be within the following range.

In the first aspect of the present invention, N is a value obtained by further dividing the value obtained by multiplying the weight average molecular weight (Mw) of the copolymer by the square of the cation colloid equivalent (CE) at pH 7 by 1,000,000. In this case, the N value is 5 to 60. That is, according to the study by the present inventors, the remarkable effect of the present invention is that a specific copolymer in which the value of N = (Mw) × (CE) ² ÷ 1 million is in the range of 5-60. It can be obtained when a polymer flocculant containing as a main component is used.

  Further, according to the study by the present inventors, among the polymer flocculants within the above-mentioned N value range, according to the polymer flocculant satisfying the requirements defined in the second invention of the present invention, It has been found that the remarkable effects of the present invention can be obtained more effectively and stably. Specifically, the second invention of the present invention is a value obtained by dividing the weight average molecular weight (Mw) of the copolymer by the cation colloid equivalent (CE) at pH 7 in addition to satisfying the above N value. When the value obtained by further dividing the value by 1 million is L, the L value is 1.5 or more. That is, a more remarkable effect of the present invention can be obtained when the value of L = (Mw) / (CE) / million is 1.5 or more. As described above, the range of the polymer flocculant specified by the L value is included in the range of the polymer flocculant specified by the N value, but also satisfies the L value as described later. By using the polymer flocculant, the effects of the present invention can be realized more stably and reliably.

  The cationic polymer flocculant made of a copolymer derived from a specific raw material monomer used in the present invention is agglomerated organic sludge as described in Patent Document 3 and Patent Document 4 mentioned above. It has been developed as a sludge dewatering agent that has a remarkable effect and is used as a sludge dewatering agent. Furthermore, in Japanese Patent No. 3352835, itaconic acid is an essential component in the specific raw material monomer used in the present invention for the purpose of improving the disadvantages of the cationic polymer flocculant used for the dewatering of the sludge. The amphoteric polymer flocculant made of a copolymer derived from raw material monomers mixed as described above is described. However, in this case as well, the sludge is used as a dehydrating agent. Of course, the objective of the present invention is “simultaneous treatment of SS from wastewater in the state where coarse SS and fine SS coexist”. Is not done at all.

  The inventors of the present invention have used spent cooling water (cooling wastewater) in a state where a large SS and a fine SS coexist and are discharged in large quantities from a casting process and a hot rolling process of an iron factory. In order to find a flocculant capable of coagulating and precipitating SS at the same time, intensive studies were conducted. As a result, in the polymer flocculant developed as a dewatering agent for sludge as described above, surprisingly, just adding to the wastewater in a state where coarse SS and fine SS coexist and float, More preferably, although the coarse SS and the fine SS coexist (coexist), and the flow rate is 0.5 m / second or more, it is added to the turbulent waste water, so that the addition amount is small. In addition, these SSs quickly aggregate and agglomerate strongly, so that they settle quickly, and the supernatant is visually recognized as suspended matter when compared with treated water treated by the conventional method. I found out that it was much clearer than ever. Furthermore, the sediment / precipitate formed by adding the polymer flocculant and aggregating and condensing coarse SS and fine SS is not in the sludge state obtained by the conventional coagulation treatment. It was found that the product was agglomerated firmly enough to be gripped and moved using a mechanical device, and the subsequent processing became extremely easy. This is because in the conventional treatment, after adding the flocculant, it was necessary to precipitate the agglomerate in the precipitation tank. However, if the polymer flocculant of the present invention is used, such a precipitation treatment can be performed. It means that it becomes unnecessary. For this reason, by utilizing the polymer flocculant of the present invention, it is possible to treat the fine SS at the same time using the conventional equipment for removing the coarse SS in advance. It is possible to realize a very large effect on the facility that the sedimentation tank which is essential in the facility can be eliminated.

（上記式中の、Ｒ₁、Ｒ₂は、それぞれ独立にＣＨ₃又はＣ₂Ｈ₅を表し、Ｒ₃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 polymer flocculant of the present invention that can achieve various remarkable effects that could not be realized by the above-described prior art is any of the monomers represented by the following general formula (1) and the following general formula (2). The main component is a cationic or amphoteric copolymer derived from a raw material monomer containing 5 mol% or more with one or both as essential components, and the copolymer has a weight average molecular weight (Mw), It is required that the N value, or the N value and the L value, defined by the cation colloid equivalent (CE) at pH 7, be within a specific range defined by the present invention.

(In the above formula, R ₁ and R ₂ each independently represent CH ₃ or C ₂ H ₅ , and R ₃ represents either H, CH ₃ or C ₂ H _5. X ⁻ represents an anion. Represents sex counter ion.)

  The cationic or amphoteric copolymer constituting the present invention can be derived from a raw material monomer containing 5 mol% or more of the monomer represented by the above formula (1) and / or (2). It is obtained by designing the monomer composition so as to satisfy the requirements of the N value or the N value and the L value specified in the above. As a specific synthesis method, for the cationic copolymer, the synthesis method described in Patent Document 4 mentioned above can be used. In addition, as described in, for example, Japanese Patent No. 3352835, the amphoteric copolymer is a cationic monomer represented by the above formula (1) and / or (2), and itaconic acid as another monomer. It can be obtained by the same method by appropriately mixing an anionic monomer such as acrylic acid or the like to obtain a raw material monomer.

  Typical examples of the monomer represented by the formula (1) include acryloyloxyethyltrimethylammonium chloride, dimethylaminoethyl acrylate hydrochloride, 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 inventors of the present invention aim to use these suspended substances from waste water in a state where coarse SS and fine SS coexist without increasing the use amount of the flocculant when used. In the process of developing a flocculant that can be removed quickly and easily by the same treatment, detailed investigations were made on the polymer flocculant obtained from the raw material monomer as described above. In this case, a cationic or amphoteric copolymer that can be derived from a raw material monomer (hereinafter also referred to as a specific raw material monomer) containing 5 mol% or more of the monomer represented by the above formula (1) and / or (2). It has been found that there is a flocculant that can achieve the object of the present invention. The inventors of the present invention, when the weight average molecular weight of the copolymer is 2 million to 13 million and the cation colloid equivalent at pH 7 is 0.4 meq / g or more, The knowledge that the intended cohesion was obtained was obtained.

  As mentioned earlier, the technical common sense is that "there is no way to remove these suspended solids from wastewater in the presence of coarse SS and fine SS in the same process." Therefore, the present inventors have recognized that the technical value of the above knowledge is extremely large. Therefore, the present inventors have found a polymer flocculant exhibiting more stable and high aggregability, and conducted further detailed studies on the polymer flocculant to be used in order to further increase the industrial value. As a result, among the copolymers derived from the raw material monomers, those satisfying the N value defined in the first invention of the present invention are effective, and among them, the second invention of the present invention is effective. The present invention has been achieved by finding that those satisfying the specified L value are effective for obtaining a more reliable and more reliable effect.

  That is, in the first invention of the present invention, the weight average molecular weight (Mw) of the cationic or amphoteric copolymer that can be derived from the above-mentioned specific raw material monomer and the square of the cation colloid equivalent (CE) at pH 7 are calculated. It is defined that the N value is 5 to 60, where N is a value obtained by dividing the multiplied value by 1 million. In addition, in the second invention of the present invention, in addition to satisfying the above N value, the weight average molecular weight (Mw) of a cationic or amphoteric copolymer that can be derived from the above-mentioned specific raw material monomer is adjusted to a pH of 7 When the value obtained by dividing the value by the cation colloid equivalent (CE) is further divided by 1,000,000, L is defined as 1.5 or more. The cation colloid equivalent used in the above rule is a value (meq / g) obtained by measuring the cation colloid equivalent per gram of the active ingredient in the polymer flocculant by the colloid titration method (method of titration with a polyvinyl potassium sulfate solution). is there. The weight average molecular weight is a value measured by a GPC (gel permeation chromatography) method in terms of polystyrene.

  The inventors of the present invention are concerned with a polymer flocculant mainly composed of a cationic or amphoteric copolymer derived from the above-mentioned specific raw material monomer. From the viewpoint of “removing these suspended solids from wastewater in the same state by the same treatment”, a detailed study was conducted. As a result, the present inventors first found out that the polymer flocculant from which the above effects are obtained more significantly has the following tendency in the characteristics of the copolymer as the main component. That is, (1) when the cation colloid equivalent is small, a copolymer having a large molecular weight tends to have a greater effect as described above, and (2) when the cation colloid equivalent is large, a copolymer having a small molecular weight is It was found that the above-mentioned effects tend to be greater.

  As a result of further studies based on the above findings, the present inventors have found that the effects of the present invention can be stably obtained when the N value of the copolymer is 5 to 60. As a result of further detailed investigation, it was found that the remarkable effects of the present invention can be obtained more stably when the L value of the copolymer is 1.5 or more. Specifically, copolymers having different weight-average molecular weight (Mw) derived from the specific raw material monomer and cation colloid equivalents (CE) at pH 7 are prepared, and using these, coarse SS and The difference in the effect was observed by vigorously adding to the waste water where fine SS coexists. As described above, the effect of the present invention is that “the coarse SS and the fine SS are quickly aggregated by the same treatment and can be easily removed, and the treated water is clarified without turbidity. It is easy to verify because it can be confirmed visually. Moreover, since the addition conditions can be achieved by high-speed stirring under the same conditions, verification is easy also in this respect.

  FIG. 1 shows various co-polymers having different N values as defined in the first invention of the present invention, which are determined from the weight average molecular weight derived from the specific raw material monomer used in the study and the cation colloid equivalent at pH 7. The difference between the coagulation / sedimentation effects obtained when the coalesces are respectively added to wastewater as polymer coagulants is evaluated and shown in four stages A to D. In AD, the effects of the present invention are recognized, but a significant effect is recognized in the order of A> B> C> D. Although D was not without the effect of coagulation / sedimentation, D was evaluated as inappropriate in view of implementation.

  From these results, the present inventors conducted further studies on the range of the polymer flocculant that can provide the remarkable effects of the present invention, and as a result, the N value of the copolymer defined in the first invention of the present invention. It was concluded that those having a value of 5 to 60 can realize a more remarkable effect. In FIG. 2, the range where the N value is 5 to 60 is indicated by a broken line. Furthermore, according to the study by the present inventors, among those within this range, the weight average molecular weight is 2 million to 13 million and the cation colloid equivalent at pH 7 is 0.7 to 4.1 meq / g. When the weight average molecular weight is 4 million to 13 million and the cation colloid equivalent at pH 7 is 1.1 to 3.5 meq / g, a remarkable effect is obtained. Speaking of the N value, a polymer flocculant having a weight average molecular weight and a colloidal equivalent of about 15 to 55 is more preferable.

  From the above, it was found that if the weight average molecular weight of the copolymer used is too small, it is difficult to obtain a sufficient SS removal effect. On the other hand, if the weight average molecular weight is too large, the viscosity increases and it becomes difficult to use. The cation colloid equivalent defined in the present invention indicates the cation density in the polymer flocculant, that is, the amount of the functional group exhibiting cationic property. As described above, according to the study by the present inventors, for the purpose of the present invention, there is an optimum range of the cation colloid equivalent in consideration of the weight average molecular weight, which is specified in the first invention of the present invention. It has been found that the remarkable effect of the present invention can be surely obtained by using a copolymer satisfying the above characteristics as a polymer flocculant. Details of the above test will be described later.

  As described above, among the copolymers derived from the above-mentioned specific raw material monomers, those satisfying the N value defined in the first invention of the present invention are for achieving the object of the present invention. It was found to be effective as a polymer flocculant. However, as shown in FIG. 2, among those satisfying the N value, it is recognized that there is a difference in the degree of coagulation / precipitation effect, and the coexistence of the coarse SS and the fine SS in the waste water to be treated. Since the state is also various, the present inventors conducted a more detailed study on the polymer flocculant to be used in order to obtain a higher flocculation / precipitation effect more stably in practical use. I realized that it was necessary to make it easier. As a result, among those satisfying the N value, a value obtained by dividing the weight average molecular weight (Mw) of the copolymer defined by the second invention of the present invention by the cation colloid equivalent (CE) at pH 7 is further obtained. When the value divided by 1 million is L, the L value is 1.5 or more, more preferably, the L value is 2.0 or more becomes a more effective flocculant. I found it.

  FIG. 3 shows a case where various copolymers derived from the specific raw material monomers used in the study and having different L values are added as polymer flocculants to waste water in which coarse SS and fine SS coexist. The obtained SS concentration in treated water is shown. The results shown in FIG. 3 also show the difference in the coagulation / sedimentation effect caused by the difference in the coarse particle concentration in the wastewater, but clearly the copolymer having an L value of 1.5 or more, By using it as a polymer flocculant, the SS of treated water was 20 mg / L or less, which was confirmed to be “A” as a relative evaluation standard of the previous aggregation / sedimentation effect. From the result of FIG. 3, the more preferable L value is 2 or more, and from the result of Table 4 described later to about 6.7. If such a polymer flocculant is used, the treated water is extremely clear. I found out that

  According to the study by the present inventors, the polymer flocculant of the present invention mainly composed of the above-described copolymer is discharged in a large amount from, for example, a hot rolling process in an iron mill, iron powder, etc. In used cooling water (waste water) in which oils such as metal and rolling oil are suspended, coarse SS and fine SS coexist and float, 0.5 mg / L or more with respect to the waste water, For example, by adding a very small amount of about 1 to 4 mg / L, suspended substances in the wastewater quickly aggregate and settle, and the supernatant becomes extremely clear (transparent) with no visible turbidity. . Although details will be described later, when the polymer flocculant of the present invention is used in a treatment performed after removing coarse SS from wastewater in advance as in the prior art, the above-described remarkable effect is obtained. Although there was a tendency for the fine SS to coagulate and settle, the supernatant was turbid with the naked eye and apparently not sufficient. This is because the remarkable aggregation, coagulation, and sedimentation effect brought about by the polymer flocculant of the present invention is caused by the coexistence of a fine suspended substance and a coarse suspended substance having a particle size of 50 μm or more. It is demonstrated for the first time when it is present, and it is important to treat waste water in a state where coarse SS and fine SS coexist and float together.

  This is also clearly shown in the results of FIG. As shown in FIG. 3, the polymer flocculant of the present invention is capable of coagulating / coagulating even when the amount of coarse SS coexisting with fine SS in wastewater is as low as about 500 to 1000 mg / L. Although a sedimentation effect was observed, in this case, it was necessary to increase the amount of the polymer flocculant added in order to obtain a more sufficient effect. On the other hand, in order to stably obtain a higher agglomeration / sedimentation effect with a smaller amount of addition using the polymer flocculant of the present invention, the abundance of coarse SS exceeds 1000 mg / L, 3000 to 5000 mg. It was found that the wastewater coexisting with about / L is preferable. Therefore, when processing wastewater with a small amount of coarse SS, the wastewater containing a large amount of coarse SS is mixed and treated, or in some cases, coarse particles such as sand are added to the wastewater. It is also effective. According to the study by the present inventors, the effect of “removing these SSs in the same treatment from the water in which coarse SS and fine SS coexist” obtained by the polymer flocculant of the present invention is processed. Even if the abundance of coarse SS in water is about 250 to 80000 mg / L, SS is more rapidly aggregated and settled when the amount is about 2000 to 20000 mg / L, and the supernatant is very clear (transparent) The agglomerated / sedimented precipitate is excellent in dewaterability with good water separation. Further, according to the study by the present inventors, the ratio of the coarse SS concentration to the fine SS concentration (rough / fine) is 2 as the mass ratio as the abundance of the coarse SS and fine SS in the waste water to be treated. When it is 0.0 or more, a remarkable effect can be obtained more stably with a small amount of the flocculant.

  Further, according to the study by the present inventors, the polymer flocculant of the present invention is, for example, a “scale for settling and removing coarse SS in wastewater discharged in large quantities from a hot rolling process in a steel mill. It may be added to a water tank called a “pit”, and a certain effect can be obtained. More preferably, for example, the used cooling water (waste water) used in the hot rolling process is added to the “scale pit”. It has been found that a higher effect can be surely obtained by adding it to a groove or a liquid channel in which wastewater until now is flowing violently. In particular, it was confirmed that it is preferable to add the “scale pit” further upstream. These facts indicate that the polymer flocculant of the present invention is added to a place where the waste water is flowing vigorously, and the polymer flocculant is reacted with coarse SS and fine SS in a vigorously mixed state. It shows that the coagulation, coagulation, and sedimentation effects are more prominently exhibited. For this reason, when there is no groove or liquid channel in which the wastewater is flowing violently, the polymer flocculant of the present invention can be configured to add the polymer flocculant while the wastewater is rapidly stirred. It is extremely effective as a method for obtaining a higher coagulation / coagulation / sedimentation effect. More specifically, according to the study by the present inventors, the coarse SS and the fine SS coexist, the flow velocity is 0.5 m / second or more, and the above-described high water is in the turbulent water. It was confirmed that a more remarkable effect can be obtained by generating a state in which the molecular flocculant coexists.

  For these reasons, the inventors of the present invention show that the polymer flocculant of the present invention has a particularly high agglomeration effect and a stronger agglomeration effect on the coarse SS. It is considered that the excellent coagulation sedimentation effect of the present invention was obtained as a result of the coexisting fine SS being incorporated into the coarse aggregate formed by the polymer flocculant of the present invention. In particular, when the wastewater is flowing in a groove or a liquid channel, it is inferred that the fine SS is actively moving in the wastewater, so that it is more easily taken in by coarse aggregates. For this reason, the aggregated sediment / precipitate obtained by adding the polymer flocculant of the present invention is completely different from the conventional sludge obtained by adding the flocculant and allowing it to settle in the sedimentation tank. It becomes coarse, can be grabbed, and has a good water separation. As a result, the agglomerated sediment / precipitate obtained when treated with the polymer flocculant of the present invention is very easy to process thereafter, and the cost for the secondary treatment is greatly increased. Reduced.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.
[Aggregation test example-1 (confirmation of effect due to coexistence of coarse SS)]
<Waste water>
By sampling the cooling wastewater discharged from the hot rolling process of the steel factory, three types of wastewater having different particle diameter ranges of coarse SS contained in the wastewater were prepared. Specifically, the range of the maximum particle size of the coarse SS was less than 50 μm, 50 μm or more and less than 200 μm, 200 μm or more and less than 1,000 μm. In addition, when the range of the maximum particle size of coarse SS prepared for comparison is less than 50 μm, the maximum particle size is 50 μm as a suspended substance by precipitating and separating waste water in advance to remove coarse SS. The waste water contains only fine SS less than. It should be noted that the range of the maximum particle size of coarse SS is 50 μm or more and less than 200 μm, or that of 200 μm or more and less than 1,000 μm, naturally, fine SS whose particle size is less than 50 μm. Is included.

<Polymer flocculant>
First, the difference in the effect due to the particle size of the coarse SS coexisting (coexisting) with the fine SS in the waste water and the effect due to the addition amount of the polymer flocculant specified in the present invention used in the test are described below. Verification was performed using Agent A. That is, as flocculant A, acrylamide / [2- (acryloyloxy) derived from raw material monomers each containing 20 mol% each of two types of monomers represented by general formulas (1) and (2) as essential components A cationic compound mainly composed of ethyl] benzyldimethylammonium chloride / [2- (acryloyloxy) ethyl] trimethylammonium chloride copolymer (molar ratio = 60/20/20) was used. Its weight average molecular weight is 3 million, and the cation colloid equivalent at pH 7 is 2.0 meq / g. Therefore, the N value of this copolymer is 12 (L value = 1.5).

<Aggregation test method>
Agglomeration tests were carried out by changing the amount of the above-mentioned flocculant A added to 2 mg / L and 4 mg / L, respectively, in the three types of wastewater having different particle sizes of the suspended substances prepared previously. Specifically, a polymer flocculant is added to a container containing waste water, stirred at a high speed for a certain period of time, and then allowed to stand to perform a coagulation sedimentation treatment. The supernatant water is treated water, and the supernatant water (treatment The SS concentration of water) was measured and evaluated. For comparison, the SS concentration of the supernatant water (treated water) was measured in the same manner except that the polymer flocculant was not added to each waste water. The obtained results are shown in Table 1.

<Test results>
As shown in Table 1, when the polymer flocculant of the present invention (flocculant A) is added compared to the case where no flocculant is added to each wastewater, the concentration of treated water SS can be reduced in any case, It confirmed that the effect as an agent was shown. Furthermore, from the results of Table 1, in particular, when the flocculant A was added to waste water containing coarse particles having a particle diameter of 50 μm or more as suspended substances, the concentration of the treated water SS was increased. The reduction effect was remarkable, and in this case, it was confirmed that the target treated water SS <10 mg / L could be easily achieved. Furthermore, the treated water obtained in this case was clear with no turbidity observed visually. In this test, waste water having a coarse SS content of about 3000 mg / L was used.

[Aggregation Test Example-2 (Examples 1-4, Comparative Examples 1-4)]
<Aggregation test method>
The wastewater whose maximum particle diameter range of coarse SS used in the previous test is 50 μm or more and less than 200 μm is used, and the addition amount of the polymer flocculant is 2 mg / L and the treatment conditions are constant. The aggregation tests of Examples 1 to 4 and Comparative Examples 1 and 2 were performed using the polymer flocculants derived by designing the monomer composition so that the N values defined in the present invention were different. Specifically, two types of monomers represented by the general formulas (1) and (2) defined in the present invention are essential components, and acrylamide / [ The test was conducted using each polymer flocculant mainly composed of 2- (acryloyloxy) ethyl] benzyldimethylammonium chloride / [2- (acryloyloxy) ethyl] trimethylammonium chloride copolymer. The amphoteric polymer flocculant shown in Table 2 uses a raw material monomer obtained by appropriately mixing itaconic acid with the two types of monomers represented by the general formulas (1) and (2) defined in the present invention. Was synthesized. For comparison, the results of Comparative Examples 3 and 4 in which similar tests were performed using nonionic and anionic polyacrylamide polymer flocculants are also shown. In this test, waste water having a coarse SS content of about 3000 mg / L was used.

<Test results>
Table 2 shows the properties of the polymer flocculants used in Examples and Comparative Examples, and the supernatant water is treated water, and the SS concentration of this supernatant water (treated water) is measured to evaluate the removability, and these are summarized. Showed. The N value in Table 2 is N = weight average molecular weight (Mw) × (cation colloid equivalent (CE)) ² ÷ 1 million, and the L value is L = weight average molecular weight (Mw) ÷ cation colloid equivalent. (CE) ÷ 1 million.

  As shown in Table 2, it was confirmed that in the example using the polymer flocculant having the property defined by the present invention, the final target water treated with SS <10 mg / L can be easily achieved. . And the obtained treated water was a clear thing which cannot recognize turbidity visually. The turbidity of the treated water of Comparative Examples 3 and 4 when a conventional acrylamide-based flocculant was used was remarkable, and further treatment was necessary. On the other hand, although it is a cationic copolymer derived from a raw material monomer containing 5 mol% or more with the monomers represented by the general formulas (1) and (2) as essential components, it is specified in the present invention. Although the polymer flocculants of Comparative Examples 1 and 2 that did not satisfy the N value showed a flocculant effect as compared with conventional acrylamide flocculants, the obtained treated water was clearly turbid.

  In addition, when the flocculation treatment is performed using a conventional acrylamide-based flocculating agent and when the flocculation treatment is performed using a polymer flocculant satisfying the requirements defined in the present invention, the properties of the aggregated sediment / precipitate are Obviously it was different. Specifically, when the flocculation treatment is performed using a conventional acrylamide-based flocculating agent, the fluffy sludge is difficult to filter. On the other hand, the aggregated and sedimented precipitate obtained when treated with the polymer flocculant of the present invention was firmly agglomerated, well separated from water, and could be picked and moved. . Furthermore, it was confirmed that when the treatment was performed using the polymer flocculant of the present invention, the aggregation and sedimentation thereof occurred very rapidly.

[Aggregation test example-3 (relation between N value and aggregation / sedimentation effect)]
<Aggregation test method>
Based on the above results, the number of types of polymer flocculants derived by designing the monomer composition so that the N values defined in the present invention are different from each other is increased, and the same as that performed in the flocculence test example-2. A test was conducted to confirm the difference in aggregation and sedimentation. Specifically, waste water whose maximum particle diameter range of coarse SS used in the previous test is 50 μm or more and less than 200 μm is used, and the amount of polymer flocculant added is 2 mg / L. The test was conducted using each polymer flocculant having different N values defined in the present invention under constant conditions, and evaluation was performed in the same manner as in the coagulation test example-2. In this test, waste water having a coarse SS content of about 3000 mg / L was used.

<Test results>
The results are shown in FIGS. 1 and 2, and the difference in the aggregation / sedimentation effect when treated using the weight average molecular weight and colloid equivalent of the polymer flocculant used in four stages of A to D. It was evaluated with. In all of AD, a coagulation / sedimentation effect was observed, but when evaluated relatively, remarkable effects were observed in the order of A>B>C> D. Although D was not without the effect of coagulation / sedimentation, D was evaluated as inappropriate in view of implementation. As a result, the value obtained by dividing the value obtained by multiplying the weight average molecular weight of the copolymer and the square of the cation colloid equivalent at pH 7 by 1 million as indicated by the broken line in FIG. In such a case, it was confirmed that a good coagulation / sedimentation effect can be realized by using a copolymer having a requirement that the N value is 5 to 60 as a coagulant. Furthermore, from FIG. 2, the weight average molecular weight is 2 million to 13 million and the cation colloid equivalent at pH 7 is 0.7 to 4.1 meq / g, and the weight average molecular weight is 4 million to 1300. It was found that when the cation colloid equivalent at pH 7 is 1.1 to 3.5 meq / g, the intended effect of the present invention is more remarkable. 1 and 2 also include the results of the aggregation test example-2.

[Aggregation Test Example-4 (Examples 5 to 8, Comparative Examples 5 to 7) (Comparison with the case of using a conventional aggregating agent)]
As a suspended substance, waste water containing coarse SS having a particle size of 50 μm or more and less than 200 μm and fine SS is prepared, and the conventional flocculants shown in Table 3 and the polymer flocculant of the present invention are prepared. The aggregating treatment was carried out in the same manner as in agglutination test example-1 for each. At that time, PAC (polyaluminum chloride) was used in Comparative Example 5, and in Comparative Example 6, PAC and an anionic polymer flocculant were used in combination. In Comparative Example 7, only this anionic polymer flocculant was used. In Examples 5 to 8, the polymer flocculant (flocculant A) used in the flocculence test example-1 was used, and the addition amount was changed from 0.5 to 4.0 mg / L. The agglutination test was performed in the same manner as in 1. Then, using the supernatant water as treated water, the SS concentration of the supernatant water (treated water) was measured to evaluate the removability. The measurement results are summarized in Table 3. In this test, waste water having a coarse SS content of about 3000 mg / L was used.

  As shown in Table 3, the present invention was compared with the concentration of treated water SS obtained by the treatment using the conventional flocculants of the comparative examples used for the flocculation treatment of suspended substances in wastewater. The treated water SS concentration obtained by the treatment using the polymer flocculant of Example 1 was clearly low. Moreover, the treated water of the Example obtained in that case was the clear water which cannot recognize turbidity visually. Furthermore, from the results of Examples 5 to 8 in which the addition amount was changed, the addition amount of the flocculant is sufficient to be about 0.5 to 4.0 mg / L in the wastewater, and it is more stable and sufficient in consideration of economy. In order to perform a proper process, it was confirmed that it may be 1.0-2.0 mg / L, for example. Therefore, when the polymer flocculant of the present invention is used, the amount of addition to the wastewater is small, and the conventional flocculant can be used alone or once without adopting a method of using the inorganic flocculant together. It was confirmed that excellent coagulation, coagulation, and sedimentation effects that could not be obtained by the coagulation treatment were obtained.

[Coagulation test example-5 (L value, abundance of coarse SS in wastewater, comparison of effects)]
In each of Test Examples 1-4 described above, the amount of coarse SS was about 3000 mg / L, and a certain amount of wastewater was used. However, since there is also low or high amount of coarse SS, The point was examined. At the same time, studies were also made on reducing the amount of the flocculant added. Specifically, waste water containing a coarse SS having a particle diameter of 50 μm or more and less than 200 μm and a fine SS was prepared as a suspended substance. At that time, the abundance of the coarse SS was 500 mg / L. , 1000 mg / L, 5000 mg / L, and three different types of wastewater were prepared. In addition, the fine SS density | concentration of the wastewater before a process was made constant at about 105 mg / L. Moreover, as a flocculant, the weight average molecular weight derived from the raw material monomer which contains 5 mol% or more as both essential components of the above-mentioned monomer represented by general formula (1) and general formula (2) is about 4 million- L value is 0.9, 1.1, 1.6, 1.9, 2.6, 3. 8 million and the cation colloid equivalent at pH 7 is 1.5 to 4.8 meq / g. The main component was 7 kinds of cationic copolymers different from 5 and 5.3.

  First, the amount of each flocculant added was reduced to 1.0 mg / L, and the above-mentioned three types of wastewaters with different abundances of coarse SS were subjected to a flocculation treatment. As a result, regardless of the abundance of coarse SS, as shown in FIG. 3, when the L value is 1.3 or more, preferably 1.8 or more, a high agglomeration / coagulation / sedimentation effect is recognized. It was. Moreover, from the result shown in FIG. 3, the amount of coarse SS coexisting with fine SS is about 5000 mg / L, and the amount of waste water having a large amount is higher than that of 500 to 1000 mg / L.・ It was found that condensation / sedimentation effects were obtained. It was also confirmed that when the amount of coarse SS coexisting with the fine SS is small, the effect can be improved by increasing the amount of the flocculant added.

[Aggregation Test Example-6 (Examples 9 to 15, Comparative Examples 8 to 10) (Study on Raw Material Monomer, Ionicity, N Value, L Value, etc.)]
From the results shown in FIG. 3, the abundance of coarse SS having a particle diameter of 50 μm or more and less than 200 μm is set to 5000 mg / L, while the concentration of fine SS having a particle diameter of less than 50 μm is 50 mg / L. Further tests were conducted using L wastewater, with the addition amount of each polymer flocculant being 2 mg / L and the treatment conditions being constant. The results are summarized in Table 4.

  As shown in Table 4, when the N value of the polymer flocculant used was in the range of 5 to 60, all of the polymer flocculants had good flocculation / coagulation / sedimentation effects. Furthermore, as a result of examining the L value of the polymer flocculant used, even when the N value is in the range of 5 to 60, if the L value is smaller than 1.5, the aggregation / sedimentation effect is inferior. confirmed. Although the reason why the L value is 1.5 or more, preferably 2.5 or more and exhibits the effect of good aggregation, coagulation, and sedimentation is unknown, the value obtained by dividing the weight average molecular weight by the cation colloid equivalent is the polymer flocculant The polymer flocculant having a higher degree of polymerization is considered to be more effective in agglomerating coarse particles and fine suspended particles in the waste water.

  As examples of use of the present invention, by using the polymer flocculant of the present invention, for example, direct cooling wastewater of steel in a continuous casting process of a steelworks, direct cooling wastewater of steel in a rolling process of a steelworks, Dust collection wastewater in the blast furnace, converter, and electric furnace process of the ironworks, rainwater wastewater generated from the outdoor raw material storage yard of the steelworks, cooling wastewater generated when obtaining granulated slag from the blast furnace pit of the steelworks, or above From a large amount of wastewater in a state where coarse SS and fine SS coexist, such as water intake in water treatment, coarse SS and fine SS can be coagulated and settled very quickly by the same treatment, which was not possible with the conventional technology. Since it can be removed, its industrial value is extremely high. In addition, by using the polymer flocculant of the present invention, the supernatant water in the case where the coarse SS and the fine SS are coagulated and settled by the same treatment clearly shows that the residual suspended matter is reduced visually. It is clear without turbidity, and can be reused as cooling water or introduced into a water purification plant. From this point, the economic effect is extremely large. Furthermore, the precipitate formed by the coagulation / aggregation of the polymer flocculant of the present invention, coarse SS and fine SS is easy to handle, can be crushed with a crumb heavy machine, and is firmly coagulated. The treatment of the precipitate can be greatly simplified, and the economic effect obtained in this respect is extremely great. The polymer flocculant of the present invention can be applied to any wastewater in which coarse SS and fine SS coexist, but in a steelworks where the amount of wastewater to be treated is extremely large. When applied to wastewater containing various suspended solids such as metal powder, granulated slag, pebbles, sand, mud, insoluble organic matter, coal powder, coke powder, and oil, and water intake treatment When applied, a particularly great effect can be expected. Furthermore, even for water containing almost no coarse SS in water, sand or the like is added in advance to make the coarse SS and fine SS coexist, and this is treated using the polymer flocculant of the present invention. Thus, the same effect can be expected when such water is treated.

Claims (4)

A coarse suspended substance having a particle size of 50 μm or more, including at least one of metal powder, coal powder or coke powder having a particle size of 50 μm or more and a fine suspended substance having a particle size of less than 50 μm coexist. The suspension is used when coagulating and sedimenting these suspended solids together by the same treatment from the waste water by containing it in the turbulent waste water having a flow rate of 0.5 m / sec or more. A polymer flocculating / sedimenting agent for turbid materials,
Mainly a cationic or amphoteric copolymer derived from a raw material monomer 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 When the value obtained by multiplying the weight average molecular weight (Mw) of the copolymer by the square of the cation colloid equivalent (CE) at pH 7 and dividing by 1 million is N, When the value is 5 to 60 and the value obtained by dividing the weight average molecular weight (Mw) of the copolymer by the cation colloid equivalent (CE) at pH 7 is further divided by 1 million, and L In addition, a polymer coagulation / sedimentation agent for suspended solids, which has an L value of 1.5 or more.

(In the above formula, R ₁ and R ₂ each independently represent CH ₃ or C ₂ H ₅ , and R ₃ represents either H, CH ₃ or C ₂ H _5. X ⁻ represents an anion. Represents sex counter ion.) Furthermore, the weight average molecular weight of from 5 to 11 million, and a polymer aggregation and precipitation agents suspended matter according to claim 1 cationic colloidal equivalent of 1.2~3.4meq / g at pH 7. A coarse suspended substance having a particle size of 50 μm or more, including at least one of metal powder, coal powder or coke powder having a particle size of 50 μm or more and a fine suspended substance having a particle size of less than 50 μm coexist. The polymer flocculent / sedimentation agent of the suspended substance according to claim 1 or 2 is added to the treated wastewater in a turbulent wastewater at a flow rate of 0.5 m / sec or more. A method for removing suspended solids from wastewater, wherein the suspended solids are coagulated and settled together by the same treatment. The method for removing suspended matter in wastewater according to claim 3 , wherein the wastewater is produced in a steel factory, and the suspended substance in the wastewater contains metal powder and oil.

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