JP2009125649A - Organic coagulant and decoloring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic coagulant which is capable of decreasing the amount of decoloring substances and suspended materials at drainage with a small amount to be used in the coagulation sedimentation treatment of drainage. <P>SOLUTION: In the organic coagulant used in coagulation sedimentation treatment of the drainage, it is characterized by being obtained by causing alkylene diamines represented by formula (1) to react with epihalohydrin and containing at least one of compounds of which the cation colloid equivalent value at pH7 is 1.0-15.0 meq/g and the weight average molecular weight Mw is 1,000-2,000,000 wherein R<SB>1</SB>, R<SB>2</SB>each denotes independently a 1-5C alkyl group, a 1-4C hydroxyalkyl group, R<SB>3</SB>, R<SB>4</SB>each denotes independently hydrogen atom, a 1-5C alkyl group and a 1-4C hydroxy alkyl group and R<SB>5</SB>denotes a 2-6C alkylene group. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an organic coagulant used in a coagulation sedimentation treatment of waste water and a method for decolorizing waste water using the organic coagulant.

  Wastewater discharged from factories handling dyes such as dyeing / printing factories and dye manufacturing factories is often colored with dyes. In addition, wastewater tends to be colored from these beverage components from beverage factories during the production of tea and coffee. There are no chromaticity items in the drainage standards, but there are organizations and companies that have established their own standards for the chromaticity of wastewater so that the colored wastewater is not released into rivers, lakes, and the sea. Conventionally, as one of the treatment methods for colored components and suspended substances in wastewater, inorganic flocculants such as polyaluminum chloride (PAC) and polymer flocculants are injected into wastewater (treated water) to form agglomerated flocs. In general, a coagulation sedimentation method in which the aggregation flocs are settled and separated is generally used.

  In such a coagulation precipitation method, in order to reduce the amount of inorganic coagulant used for removing colored components, for example, Patent Documents 1 and 2 include organic coagulants such as polyamine and polydiallyldimethylammonium chloride. It is described that it is used in combination with an inorganic coagulant. Patent Document 3 describes a method for treating purified water in which an organic coagulant such as polyamine or an inorganic coagulant and an organic coagulant are added to and mixed with wastewater, and then a polymer coagulant is added and mixed. .

Japanese Patent Publication No. 52-34854 Japanese Examined Patent Publication No. 7-41247 JP 2002-346572 A

  The coloring component that gives chromaticity is easy to color waste water even at a very small concentration. Depending on the quality of the drainage water, an extremely large amount of inorganic coagulant is required to reduce the amount of coloring components and suspended substances to a chromaticity that does not cause discomfort to humans. Even if the coagulant is used in combination with an inorganic coagulant, the amount of sludge generated is still large, and there remains a problem that an economic burden and an environmental load are applied.

  The present invention relates to an organic coagulant capable of reducing the amount of colored substances and suspended substances in wastewater (treated water) and a decolorization of wastewater using the organic coagulant in coagulation sedimentation treatment of wastewater. Is the method.

  The present invention is an organic coagulant used in the coagulation sedimentation treatment of waste water, obtained by reacting an alkylenediamine represented by the following general formula (1) and epihalohydrin, and having a cation colloid equivalent value of 1 at pH 7. An organic coagulant containing at least one compound having a weight average molecular weight Mw of 1,000 to 2,000,000 and a weight average molecular weight Mw of .0 to 15.0 meq / g.

（式中、Ｒ₁，Ｒ₂はそれぞれ独立して炭素数１〜５のアルキル基、炭素数１〜４のヒドロキシアルキル基を示し、Ｒ₃，Ｒ₄はそれぞれ独立して水素原子、炭素数１〜５のアルキル基、炭素数１〜４のヒドロキシアルキル基を示し、Ｒ₅は炭素数２〜６のアルキレン基を示す。）

(In the formula, R ₁ and R ₂ each independently represent an alkyl group having 1 to 5 carbon atoms and a hydroxyalkyl group having 1 to 4 carbon atoms, and R ₃ and R ₄ each independently represent a hydrogen atom and a carbon number. An alkyl group having 1 to 5 carbon atoms and a hydroxyalkyl group having 1 to 4 carbon atoms, and R ₅ represents an alkylene group having 2 to 6 carbon atoms.)

In the organic coagulant, it is preferable that R ₁ and R ₂ are each independently an alkyl group having 1 to 5 carbon atoms, and R ₃ and R ₄ are hydrogen atoms.

In the organic coagulant, it is preferable that R ₁ and R ₂ are a methyl group or an ethyl group, and R ₅ is an ethylene group or a propylene group.

  The present invention is also a decolorization method for performing decolorization treatment of waste water, wherein 0.1 to 2,000 (mg / L) of the organic coagulant is added to the waste water, and further inorganic coagulation is performed as necessary. This is a decolorization method in which 10 to 5,000 (mg / L) of an agent is added and the pH is adjusted to 3 to 12, and then a polymer flocculant is added and processed.

  In the present invention, by using an organic coagulant containing at least one kind of the compound represented by the above general formula (1), in the coagulation sedimentation treatment of the wastewater, the colored substance or suspension in the wastewater can be used with a small amount. The amount of substance can be reduced.

  Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

<Organic coagulant>
As a result of intensive studies, the inventors of the present invention obtained by reacting an alkylenediamine represented by the following general formula (1) with epihalohydrin and having a cation colloid equivalent value at pH 7 of 1.0 to 15.0 meq / g. And using an organic coagulant containing at least one compound having a weight average molecular weight Mw of 1,000 to 2,000,000, or using the organic coagulant in combination with an inorganic coagulant. It has been found that the amount of colored substances and suspended substances in the waste water can be reduced with a smaller amount of use than conventional organic coagulants if the coagulation sedimentation treatment is performed.

（式中、Ｒ₁，Ｒ₂はそれぞれ独立して炭素数１〜５のアルキル基、炭素数１〜４のヒドロキシアルキル基を示し、Ｒ₃，Ｒ₄はそれぞれ独立して水素原子、炭素数１〜５のアルキル基、炭素数１〜４のヒドロキシアルキル基を示し、Ｒ₅は炭素数２〜６のアルキレン基を示す。）

(In the formula, R ₁ and R ₂ each independently represent an alkyl group having 1 to 5 carbon atoms and a hydroxyalkyl group having 1 to 4 carbon atoms, and R ₃ and R ₄ each independently represent a hydrogen atom and a carbon number. An alkyl group having 1 to 5 carbon atoms and a hydroxyalkyl group having 1 to 4 carbon atoms, and R ₅ represents an alkylene group having 2 to 6 carbon atoms.)

  Examples of the alkyl group having 1 to 5 carbon atoms include linear and branched alkyl groups having 1 to 5 carbon atoms, such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, t -Butyl group, sec-butyl group, n-pentyl group, etc. are mentioned. Of these, a methyl group or an ethyl group is preferable.

  Examples of the hydroxyalkyl group having 1 to 4 carbon atoms include a hydroxymethyl group, a hydroxyethyl group, a 2-hydroxypropyl group, a 3-hydroxypropyl group, a 2-hydroxybutyl group, a 3-hydroxybutyl group, and a 4-hydroxybutyl group. Groups and the like.

  Examples of the alkylene group having 2 to 6 carbon atoms include an ethylene group, a propylene group, a butylene group, a pentylene group, and a hexylene group.

  The weight average molecular weight Mw of the compound obtained by reacting the alkylene diamines with epihalohydrin is in the range of 1,000 to 2,000,000, preferably in the range of 2,000 to 500,000, A range of 000 to 300,000 is more preferable. When the weight average molecular weight Mw is less than 1,000, the effect is inferior, and when it exceeds 2,000,000, the viscosity becomes extremely high and handling becomes difficult.

  The cation colloid equivalent value at pH 7 of the compound obtained by reacting the alkylenediamine with epihalohydrin is in the range of 1.0 to 15.0 meq / g, but in the range of 4.0 to 12.0 meq / g. The range of 6.0-10.0 meq / g is more preferable. The cation colloid equivalent value is an index representing the number of cations in the compound. If the cation colloid equivalent value is less than 1.0 meq / g, the effect of reducing chromaticity in the coagulation precipitation treatment is reduced, and 15.0 meq / g is reduced. If it exceeds, floc formation worsens. The organic coagulant according to the present embodiment is considered to have a high coagulability because it has a higher cation colloid equivalent value than polyamine, polydiallyldimethylammonium chloride and the like conventionally used as organic coagulants.

  By using an organic coagulant containing at least one compound obtained by reacting the alkylene diamines and epihalohydrin according to the present embodiment, coloring in waste water with a small amount of use in coagulation sedimentation treatment of waste water. The amount of substances and suspended substances can be reduced. As a result, the amount of generated sludge can be reduced.

<Method for decolorizing drainage>
Next, a method for decolorizing wastewater using an organic coagulant according to an embodiment of the present invention will be described.

  First, the organic coagulant is added to and mixed with waste water (treated water), and further, an inorganic coagulant is added and mixed as necessary, and a pH adjuster is added to adjust the pH.

  The amount of the organic coagulant added is not particularly limited as long as it is determined according to the properties of the wastewater to be treated. For example, it is in the range of 0.1 mg / L to 2000 mg / L, and used in combination with the inorganic coagulant. Is, for example, in the range of 0.1 mg / L to 300 mg / L.

  As the inorganic coagulant, an inorganic coagulant such as iron or aluminum generally used as a coagulant can be used. Specific examples include a sulfuric acid band, polyaluminum chloride (PAC), aluminum chloride, polyferric sulfate (polyiron), ferric chloride, and a mixture thereof.

  The amount of the inorganic coagulant added is not particularly limited as long as it is determined according to the properties of the wastewater to be treated, but is, for example, in the range of 10 mg / L to 5000 mg / L.

  The organic coagulant and the inorganic coagulant may be used either alone or in the form of a mixture. However, the organic coagulant, the inorganic coagulant, and a mixture thereof are previously diluted with a solvent such as water. Alternatively, it may be used in the state of a suspension or the like. When the organic coagulant and the inorganic coagulant are used in combination, the order of adding the organic coagulant and the inorganic coagulant to the wastewater is not particularly limited.

  The pH of the wastewater may be adjusted to pH 3-12. When an inorganic coagulant such as a sulfuric acid band or polyaluminum chloride (PAC) is used, a pH range of 5 to 9 is preferable, and a pH range of 6 to 8 is more preferable. When an iron-based one such as ferric chloride is used as the inorganic coagulant, a pH range of 4 to 11 is preferable, and a pH range of 5 to 10 is more preferable.

  As the pH adjuster, an acid such as hydrochloric acid or sulfuric acid, or an alkali such as sodium hydroxide or calcium hydroxide is used.

  After adding and mixing the organic coagulant to the waste water (treated water), adding and mixing the inorganic coagulant as necessary, and adjusting the pH by adding the pH adjuster, Add molecular flocculant.

  Examples of the polymer flocculant used include known anionic, nonionic, and cationic polymer flocculants.

  Examples of the anionic polymer flocculant include polyacrylamide partial hydrolysates, copolymers of anionic monomers, and copolymers of anionic monomers and nonionic monomers such as acrylamide.

  As anionic monomers, acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, vinyl sulfonic acid, allyl sulfonic acid, methacryl sulfonic acid, styrene sulfonic acid, 2-allylamidoethanesulfonic acid, 2-acrylamide-2 -Methylpropanesulfonic acid, 2-methacrylamideamidoethanesulfonic acid, 2-methacrylamide-2-methylpropanesulfonic acid, 2-acryloyloxyethanesulfonic acid, 3-acryloyloxypropanesulfonic acid, 4-acryloyloxybutanesulfonic acid, Examples include 2-methacryloyloxyethanesulfonic acid, 3-methacryloyloxypropanesulfonic acid, 4-methacryloyloxybutanesulfonic acid, and metal salts or ammonium salts of these alkali metals and alkaline earth metals. It is. These anionic monomers may be used alone or in combination of two or more.

  Nonionic monomers include acrylamide, methacrylamide, methacrylonitrile, vinyl acetate and the like. These nonionic monomers may be used alone or in combination of two or more.

  Preferable copolymers are acrylamide, acrylate copolymer, and acrylamide-2-acrylamido-2-methylpropanesulfonic acid copolymer.

  The nonionic polymer flocculant is a polymer or copolymer of the above-mentioned nonionic monomer, preferably polyacrylamide.

  The cationic polymer flocculant has a cationic monomer as an essential component, and is a copolymer of a cationic monomer or a copolymer of a cationic monomer and the nonionic monomer.

  Examples of the cationic monomer include dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, or a neutralized salt or quaternary salt thereof. A cationic polymer flocculant containing an amidine unit in the molecule can also be used.

  Examples of the polymer flocculant include so-called amphoteric polymer flocculants obtained by copolymerizing a cationic monomer unit, an anionic monomer unit, and a nonionic monomer unit.

  The polymer flocculant may be any of anionic, nonionic, and cationic, but anionic or nonionic polymer flocculants are preferred from the standpoint of floc sedimentation.

  The polymer flocculants can be used alone or in combination of two or more. The amount of the polymer flocculant added is not particularly limited as long as it is determined according to the properties of the wastewater to be treated, but is, for example, in the range of 0.5 to 10 mg / L.

  In the present embodiment, the wastewater to be treated is not particularly limited as long as it is a wastewater containing coloring components and suspended substances. For example, colored wastewater discharged from a dyeing / printing factory, dye manufacturing factory, etc., colored wastewater containing tea, coffee, etc. discharged from a beverage factory etc. and wastewater containing suspended substances. The decoloring method according to the present embodiment is used for decoloring treatment for these colored wastewater and the like. Since the decolorization method according to the present embodiment uses the principle that an organic coagulant having a cationic group and a colored component having an anionic functional group or the like specifically react, the treatment target is limited to the colored component. It is not something. Specifically, it can also be applied to removal of substances such as anionic surfactants and organic compounds having a carboxylic acid group or a sulfonic acid group contained in waste water.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely in detail, the present invention is not limited to the following examples.

(Examples 1-8)
Using Congo Red 50 mg / L simulated waste water (color 807 degrees, turbidity 0.0 degrees) as the water to be treated, a coagulation precipitation test was conducted by the jar tester method shown below. After adding and mixing the organic coagulant and inorganic coagulant shown in Table 1 to the water to be treated at predetermined effective concentrations and addition concentrations, the pH was adjusted to the predetermined pH. Furthermore, polymer flocculants of the type shown in Table 1 were added and mixed at a predetermined addition concentration. As the organic coagulant, an organic coagulant (organic coagulant A) containing a compound (weight average molecular weight Mw = 208,000) obtained by reacting an alkylenediamine and epihalohydrin is used, and as the inorganic coagulant, PAC is used. (Examples 1 to 3, 6 to 8), iron chloride (Example 4), and sulfuric acid band (Example 5) were used. As the polymer flocculant, the following anionic polymer flocculants (a) to (c) were used. In the test, a solution dissolved in pure water was used so that the organic coagulant was 2% (w / v) and the polymer flocculant was 0.1% (w / v). The inorganic coagulant was used in the form of an aqueous solution. Table 1 shows the results of the coagulation sedimentation test using a jar tester (the floc diameter in the treatment liquid and the chromaticity of the treatment liquid (supernatant water)). The treatment pH was adjusted to 7 ± 0.1.

<Measurement method of weight average molecular weight Mw>
The weight average molecular weight Mw of the organic coagulant was measured by determining the weight average from the molecular weight distribution obtained by HPLC analysis.
(HPLC conditions)
Column: manufactured by Tosoh Corporation, TSKgel GMPW × 2 (7.5 mm LD. × 30 cmL × 2)
Eluent: 0.5M CH ₃ COOH + 0.2M NaNO ₃
Flow rate: 1.0 mL / min
Sample injection volume: 100 μL
Column temperature: 40 ° C
Detector: manufactured by Tosoh Corporation, HLC-8120GPC (with built-in RI)
Detection condition: RI (polarity (+), response (1.0 sec))
Sample preparation: measurement sample diluted with eluent Sample concentration: 1.0 g / L (solid content 0.1%)
Molecular weight marker: Standard PEO, PEG (0.5 g / L)

<Polymer flocculant>
(A) Acrylic acid / acrylamide copolymer (anion colloid equivalent value -2.9 meq / g, salt viscosity 150 mPa · s)
(B) Acrylic acid / acrylamide copolymer (anion colloid equivalent value -4.9 meq / g, salt viscosity 250 mPa · s)
(C) Acrylic acid / acrylamide copolymer (anion colloid equivalent value -1.0 meq / g salt viscosity 150 mPa · s)

<Jar tester method>
(1) Dispense simulated waste water into a 500 mL beaker.
(2) Add a predetermined amount of organic coagulant and stir at 150 rpm for 60 seconds.
(3) A predetermined amount of an inorganic coagulant is added and stirred at 150 rpm for 60 seconds.
(4) Sodium hydroxide (prepared to 5%) Adjust to a predetermined pH and stir at 150 rpm for 5 minutes.
(5) A predetermined amount of the polymer flocculant is added and stirred at 150 rpm for 60 seconds, and slowly stirred at 40 rpm for 60 seconds.
(6) After standing for 5 minutes, the floc diameter, chromaticity and turbidity of the supernatant are measured.

  The floc diameter of the supernatant was measured visually. For measurement of chromaticity and turbidity, “Water Analyzer 2000N” manufactured by Nippon Denshoku Industries Co., Ltd., whose chromaticity is a transmitted light measurement method and whose turbidity is an integrating sphere photoelectric photometry method, was used. . The chromaticity is based on JIS standard JIS K0101: 10.1 “Chromaticity by platinum / cobalt (colorimetric method)” or JIS K0102: 11 “chromaticity”, and the turbidity is JIS standard JIS K0101: 9.4 “integrating sphere”. Measured based on turbidity.

  Further, the cation colloid equivalent value of the organic coagulant used in Example 1 (measured value at pH 7, g of denominator is converted to pure content) was 8.6 meq / g. The cation colloid equivalent value of the organic coagulant was determined by the following method by colloid titration.

<Colloidal titration method>
1. Method for Analyzing Cation Colloid Equivalent Value (1) Measure the evaporation residue (%) of the sample in advance.
(2) Take 100 mL of a sample diluted to 50 mg / L with pure water in a beaker.
(3) Adjust the pH to 7 with hydrochloric acid or aqueous sodium hydroxide and stir for about 1 minute.
(4) Add 2-3 drops of toluidine blue indicator and stir.
(5) Titrate with potassium N / 400 potassium sulfate reagent (N / 400 PVSK). The titration rate is about 2 mL / min. The end point is the point at which the sample is held for 10 seconds or more after the sample color changes from blue to magenta.
(6) Colloid equivalent value (meq / g [pure content]) = PVSK titration (mL) × PVSK factor / 2 / evaporation residue (%) × 100
2. Analysis method of anion colloid equivalent value (1) The evaporation residue (%) of the sample is measured in advance.
(2) Add “pure water: 95 mL” and “N / 200-methylglycol chitosan (MGK) aqueous solution: 5.0 mL” to the beaker, then add “0.1 N NaOH: 0.5 mL” and stir for 1 minute. To do.
(3) Add 5.0 mL of the sample diluted to 1,000 mg / L to (2) and stir for 5 minutes.
(4) Add 2-3 drops of toluidine blue indicator and stir.
(5) Titrate with potassium N / 400 potassium sulfate reagent (N / 400 PVSK). The titration rate is about 2 mL / min. The end point is the point at which the sample is held for 10 seconds or more after the sample color changes from blue to magenta.
(6) A blank test (pure water: 100 mL) is performed in the same manner as described above.
(7) Colloid equivalent value (meq / g [pure content]) = (blank titration (mL) −sample titration (mL)) × PVSK factor / 2 / evaporation residue (%) × 100

(Examples 9 and 10)
Example 1 except that an organic coagulant (organic coagulant A ′) containing a compound (weight average molecular weight Mw = 6,700) obtained by reacting an alkylenediamine and epihalohydrin was used as the organic coagulant. , 2 were each subjected to coagulation sedimentation treatment. The results are shown in Table 1. Further, the cation colloid equivalent value of the organic coagulant A ′ used in Examples 9 and 10 was measured and found to be 8.1 meq / g.

(Comparative Examples 1-3)
A coagulation-precipitation treatment was performed in the same manner as in Example 1 except that an inorganic coagulant was used as shown in Table 1 without using an organic coagulant. The results are shown in Table 1.

(Comparative Examples 4 to 8)
Except having used the organic coagulant (organic coagulant B) containing a dimethylamine epichlorohydrin condensate (weight average molecular weight Mw = 40,000) as an organic coagulant, it carried out similarly to Examples 1-5. Each was subjected to a coagulation sedimentation treatment. The results are shown in Table 1. Moreover, it was 6.7 meq / g when the cation colloid equivalent value of the organic coagulant B used in Comparative Examples 4-8 was measured.

(Comparative Examples 9-13)
A coagulation precipitation treatment was carried out in the same manner as in Examples 1 to 5, except that an organic coagulant (organic coagulant C) containing polydimethyldiallylammonium salt (weight average molecular weight Mw = 300,000) was used as the organic coagulant. Went. The results are shown in Table 1. Moreover, it was 6.0 meq / g when the cation colloid equivalent value of the organic coagulant C used by Comparative Examples 9-13 was measured.

  By comparing Examples 1 and 9 with Comparative Examples 4 and 9, it can be seen that the organic coagulants A and A 'of Examples 1 and 9 have the most chromaticity reducing effect. Further, by comparing Examples 1 and 9, Comparative Examples 5 and 6, and Comparative Examples 10 and 11, for example, when the target chromaticity of treated water is set to 5 degrees or less, the organic coagulant B of Comparative Example, In C, when the amount of the organic coagulant is 1.0 (mg / L), the amount of the coagulant inorganic coagulant cannot be achieved when the amount is 250 (mg / L), and 500 (mg / L) is required. When the organic coagulants A and A ′ of 1 and Example 9 were used, the same organic coagulant amount 1.0 (mg / L), the combined inorganic coagulant amount 250 (mg / L) and the chromaticity 5 It can be seen that the following can be achieved. It can also be seen that the higher the cation colloid equivalent value of the organic coagulant used, the higher the chromaticity reduction effect.

(Examples 11-13, Comparative Examples 14-20)
As water to be treated, commercially available green tea pure water 4 times diluted water (pH 7, chromaticity 225 degrees, turbidity 1.7 degrees, pH 6, chromaticity 184 degrees, turbidity 1.7 degrees) Using the organic coagulant, the inorganic coagulant, and the polymer coagulant as shown in Table 2, the coagulation precipitation test by the above jar tester method was performed. The results are shown in Table 2. The treatment pH was adjusted to 7 ± 0.1 for Examples 11 and 12 and Comparative Examples 14 to 17, and 6 ± 0.1 for Example 13 and Comparative Examples 18 to 20.

  Thus, it can be seen that the organic coagulants A and A ′ of Examples 11 to 13 have the most chromaticity reduction effect and turbidity reduction effect. Further, it can be seen that the treatment pH of 6 has a chromaticity reducing effect and a turbidity reducing effect, rather than 7.

(Example 14, Comparative Examples 21-23)
Using treated wastewater (colored wastewater analysis value is Table 3) and using organic coagulant, inorganic coagulant and polymer flocculant as shown in Table 4, coagulation by the above jar tester method The results of the precipitation test are shown in Table 4. The treatment pH was all adjusted to 7 ± 0.1.

  Thus, it turns out that the organic coagulant A of Example 14 has the most chromaticity reduction effect and turbidity reduction effect.

Claims (4)

An organic coagulant used in the coagulation sedimentation treatment of waste water,
It is obtained by reacting an alkylenediamine represented by the following general formula (1) with epihalohydrin, has a cation colloid equivalent value at pH 7 of 1.0 to 15.0 meq / g, and has a weight average molecular weight Mw of 1, An organic coagulant characterized by containing at least one compound selected from 000 to 2,000,000.

(In the formula, R ₁ and R ₂ each independently represent an alkyl group having 1 to 5 carbon atoms and a hydroxyalkyl group having 1 to 4 carbon atoms, and R ₃ and R ₄ each independently represent a hydrogen atom and a carbon number. An alkyl group having 1 to 5 carbon atoms and a hydroxyalkyl group having 1 to 4 carbon atoms, and R ₅ represents an alkylene group having 2 to 6 carbon atoms.) The organic coagulant according to claim 1,
The organic coagulant characterized in that R ₁ and R ₂ are each independently an alkyl group having 1 to 5 carbon atoms, and R ₃ and R ₄ are hydrogen atoms. The organic coagulant according to claim 2,
R ₁ and R ₂ are a methyl group or an ethyl group, and R ₅ is an ethylene group or a propylene group. A decolorizing method for decolorizing wastewater,
The organic coagulant according to any one of claims 1 to 3 is added to the waste water in an amount of 0.1 to 2,000 (mg / L), and the inorganic coagulant is added in an amount of 10 to 5, if necessary. 000 (mg / L) is added, the pH is adjusted to 3 to 12, and then a polymer flocculant is added for treatment.