Treatment agent for wastewater containing zinc and nickel and wastewater treatment method

Abstract

To provide a wastewater treatment agent and wastewater treatment method, capable of removing zinc and nickel from wastewater containing zinc and nickel.SOLUTION: Disclosed are: a wastewater treatment agent including an inorganic sulfide (A), a polydiallylamine (B) in which two or more repeating units represented by general formula (1) and / or (2) are repeated, and an organic amine compound (C) having at least three carboxyl groups and one hydroxy group, wherein based on 100 pts.mass of (A), (B) is included in an amount of 0.1-300 pts.mass, and (C) is included in an amount of 0.2-2.5 pts.mass; and a wastewater treatment method using the wastewater treatment agent.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a treatment agent and a wastewater treatment method that enable the removal of zinc and nickel from wastewater containing zinc and nickel. [Background technology]

[0002] There is concern that wastewater containing zinc and nickel discharged from plating factories and other plants may affect ecosystems due to their toxicity. For this reason, the wastewater must be sent to a wastewater treatment facility where the zinc and nickel are removed before it is discharged.

[0003] The discharge standards for zinc and nickel concentrations in wastewater are set for each metal by the Water Pollution Control Law. There is no uniform discharge standard for nickel, but local governments have set standards. For example, Kyoto Prefecture has set a standard of 2 mg / L, and Yokohama City has set an even stricter standard of 1 mg / L.

[0004] Meanwhile, a uniform discharge standard of 2 mg / L has been set for zinc. Previously, the zinc standard was set at 5 mg / L, which was strengthened to 2 mg / L in 2006. However, provisional discharge standards were set until Reiwa 3 for three industries (metal mining, sewerage, and electroplating) that discharge zinc and for which it is difficult to immediately achieve the uniform discharge standard. Two of the three industries (metal mining and sewerage) moved to the uniform discharge standard in Reiwa 3, but the remaining electroplating industry has a provisional standard of 4 mg / L until Reiwa 6, as it is difficult to achieve the uniform discharge standard. This shows that zinc wastewater treatment in the electroplating industry is extremely difficult.

[0005] One of the reasons why it is difficult to achieve the zinc wastewater standards is the presence in the wastewater of complexing agents that have the ability to form complexes with zinc (such as organic acids such as citric acid, gluconic acid, tartaric acid, lactic acid, nitrilotriacetic acid (NTA) or ethylenediaminetetraacetic acid (EDTA), amine compounds such as ethylenediamine or polyethyleneimine, cyanide, ammonia, or polyphosphoric acid) used in the zinc-nickel plating process.

[0006] In response to this, methods have been reported for removing zinc or nickel from wastewater containing zinc or nickel using chemicals, such as inorganic sulfides, such as sodium hydrogen sulfide, or organic chelates, such as dithiocarbamates (e.g., Patent Documents 1 to 4). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2018-69227 A [Patent Document 2] JP 2017-154130 A [Patent Document 3] JP 2022-94340 A [Patent Document 4] JP 2019-69434 A Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the case of inorganic sulfides, zinc may not be sufficiently removed from wastewater when the concentration of the complexing agent is high, and in the case of dithiocarbamates, zinc may not be sufficiently removed from wastewater containing both zinc and nickel.

[0009] As described above, it has been found that it is difficult to simultaneously remove zinc and nickel from wastewater containing a carboxylic acid compound (complexing agent), zinc, and nickel using conventionally known treatment agents, and there has been a demand for the development of a wastewater treatment agent capable of removing both zinc and nickel from such wastewater. [Means for solving the problem]

[0010] Means for Solving the Problems The present inventors have conducted intensive research to solve the above problems, and as a result have discovered the invention described below and completed the present invention.

[0011] That is, the present invention has the following gist.

[0012] [1] A wastewater treatment agent comprising: an inorganic sulfide (A); a polydiallylamine (B) having at least two repeating units represented by the following general formula (1) and / or (2); and an organic amine compound (C) having at least three carboxy groups and one hydroxy group, the wastewater treatment agent comprising 0.1 to 300 parts by mass of (B) and 0.2 to 2.5 parts by mass of (C) relative to 100 parts by mass of (A):

[0013] [ka]

[0014] (In the formula, R 1 , R 2 , and R 3 Each of X independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. - represents a fluoride ion, a chloride ion, a bromide ion, an iodide ion, or an ethyl sulfate anion. [2] The wastewater treatment agent according to [1], further comprising a compound (D) having a dithiocarbamic acid group, the content of the compound (D) being 1 to 200 parts by mass per 100 parts by mass of the compound (A).

[0015] [3] The wastewater treatment agent according to [1] or [2], wherein the inorganic sulfide (A) is sodium hydrogen sulfide, sodium sulfide, potassium sulfide, or calcium polysulfide.

[0016] [4] The wastewater treatment agent according to any one of [1] to [3], wherein the polydiallylamine (B) has an average molecular weight of 1,000 to 500,000.

[0017] [5] R 1 , R 2 , and R 3 are each independently a hydrogen atom, a methyl group, or an ethyl group.

[0018] [6] R 1 , and R 2 are both methyl groups or both ethyl groups, and R 3 The wastewater treatment agent according to any one of [1] to [5], wherein is a hydrogen atom.

[0019] [7] X - The wastewater treatment agent according to any one of [1] to [6], wherein is a chloride ion.

[0020] [8] The wastewater treatment agent according to any one of [1] to [7], wherein the organic amine compound (C) having at least three carboxy groups and one hydroxy group is hydroxyiminodisuccinic acid, hydroxyethylethylenediaminetriacetic acid, or diaminohydroxypropanetetraacetic acid.

[0021] [9] The wastewater treatment agent according to any one of [1] to [8], further comprising water, the content of the water being 100 to 5000 parts by mass per 100 parts by mass of the (A).

[0022]

[10] A wastewater treatment method comprising adding a wastewater treatment agent according to any one of [1] to [9] to wastewater containing a carboxylic acid compound, zinc, and nickel, stirring the mixture, then adding a polymer flocculant and stirring the mixture to form a slurry, and then separating a solid component from the slurry.

[0023]

[11] The wastewater treatment method according to

[10] , wherein the carboxylic acid compound is citric acid, tartaric acid, lactic acid, or ethylenediaminetetraacetic acid.

[0024]

[12] A wastewater treatment method comprising adding an inorganic sulfide (A), a polydiallylamine (B) having at least two or more repeating units represented by the following general formula (1) and / or (2), and an organic amine compound (C) having at least three carboxy groups and one hydroxy group to wastewater containing a carboxylic acid compound, zinc, and nickel, and stirring the mixture, then adding a polymer flocculant and stirring to form a slurry, and then separating a solid component from the slurry, wherein the amount of (B) added is 0.1 to 300 parts by mass per 100 parts by mass of (A), and the amount of (C) added is 0.2 to 2.5 parts by mass per 100 parts by mass of (A).

[0025] [ka]

[0026] (In the formula, R 1 , R 2 , and R 3 Each of X independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. - represents a fluoride ion, a chloride ion, a bromide ion, an iodide ion, or an ethyl sulfate anion.

[13] The wastewater treatment method according to

[12] , further comprising adding a compound (D) having a dithiocarbamic acid group in addition to the compounds (A), (B), and (C).

[0027]

[14] The wastewater treatment method according to

[12] or

[13] , wherein the amount of the inorganic sulfide (A) added is 0.1 to 20 mol per 1 mol of zinc in the wastewater. Effect of the Invention

[0028] The wastewater treatment agent of the present invention exerts a remarkable effect of being able to simultaneously remove zinc and nickel to a high degree from wastewater containing a carboxylic acid compound, zinc, and nickel. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] The present invention will be described in detail below.

[0030] One aspect of the present invention relates to a wastewater treatment agent comprising an inorganic sulfide (A), a polydiallylamine (B) having at least two repeating units represented by the following general formula (1) and / or (2), and an organic amine compound (C) having at least three carboxy groups and one hydroxy group, the wastewater treatment agent comprising 0.1 to 300 parts by mass of (B) and 0.2 to 2.5 parts by mass of (C) per 100 parts by mass of (A):

[0031] [ka]

[0032] (In the formula, R 1 , R 2 , and R 3 Each of X independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. - represents a fluoride ion, a chloride ion, a bromide ion, an iodide ion, or an ethyl sulfate anion. The inorganic sulfide (A) is not particularly limited, but examples thereof include sodium sulfide, sodium hydrogen sulfide, potassium sulfide, potassium hydrogen sulfide, potassium polysulfide, calcium sulfide, calcium hydrogen sulfide, calcium polysulfide (lime sulfur mixture), magnesium hydrogen sulfide, and ammonium sulfide.

[0033] Among these, sodium hydrogen sulfide, sodium sulfide, potassium sulfide, or calcium polysulfide is preferred, and sodium hydrogen sulfide is more preferred, because they are excellent in simultaneous removal of zinc and nickel.

[0034] In the general formulas (1) and (2), R 1 , R 2 , and R 3 each independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.

[0035] The alkyl group having 1 to 10 carbon atoms can be rephrased as a linear, branched, or cyclic alkyl group having 1 to 10 carbon atoms, and is not particularly limited, but examples thereof include a methyl group, an ethyl group, a linear alkyl group having 3 to 10 carbon atoms, a branched alkyl group having 3 to 10 carbon atoms, and a cyclic alkyl group having 3 to 10 carbon atoms.

[0036] The linear alkyl group having 3 to 10 carbon atoms, the branched alkyl group having 3 to 10 carbon atoms, or the cyclic alkyl group having 3 to 10 carbon atoms is not particularly limited, and examples thereof include a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a sec-butyl group, a pentyl group, an isopentyl group, a 1-methylbutyl group, a 1-ethylpropyl group, a 1,1-dimethylpropyl group, a 2,2-dimethylpropyl group, a hexyl group, a 1-methylpentyl group, a 2-methylpentyl group, a 3-methylpentyl group, a 4-methylpentyl group, a 1,1-dimethyl-butyl group, a 1,2-dimethyl-butyl group, a 1,3-dimethyl-butyl group, a 2,2-dimethyl-butyl group, a 2,3-dimethyl-butyl group, a 1,1-dimethyl-2-methyl-propyl group, a 1-dimethyl-2,2-dimethyl-propyl group, a cyclohexyl group, a heptyl group, an octyl group, a nonyl group, and a decyl group.

[0037] R 1 , R 2 , and R 3 Regarding the groups, it is preferable that each of them independently be a hydrogen atom, a methyl group, or an ethyl group, in terms of being excellent in simultaneous removal of zinc and nickel.

[0038] R 1 , and R 2 Regarding the groups, it is more preferable that both groups are methyl groups or ethyl groups, since these groups are excellent in simultaneous removal of zinc and nickel.

[0039] R 3 With regard to , it is more preferable that it is a hydrogen atom, since this is excellent in the simultaneous removal of zinc and nickel.

[0040] In the general formula (1), X - represents a fluoride ion, a chloride ion, a bromide ion, an iodide ion, or an ethyl sulfate anion. - Regarding the ion, chloride ions are preferred because they are excellent in the simultaneous removal of zinc and nickel.

[0041] The polydiallylamine (B) characterized by having at least two or more repeating units represented by the above general formula (1) and / or (2) is not particularly limited, and examples thereof include poly(diallylamine), poly(methyldiallylamine), poly(ethyldiallylamine), poly(diallyldimethylammonium chloride), poly(diallylmethylethylammonium chloride), poly(diallyldiethylammonium chloride), poly(diallyldimethylammonium bromide), poly(diallyldiethylammonium bromide), poly(diallyldimethylammonium iodide), poly(diallyldiethylammonium iodide), or poly(diallyldiethylammonium ethylsulfate), poly(propyldiallylamine), poly(iso-propyldiallylamine), poly(butyldiallylamine), poly(iso-butyldiallylamine), poly(t poly(ert-butyldiallylamine), poly(sec-butyldiallylamine), poly(pentyldiallylamine), poly(isopentyldiallylamine), poly(1-methylbutyldiallylamine), poly(1,1-dimethylpropyldiallylamine), poly(2,2-dimethylpropyldiallylamine), poly(hexyldiallylamine), poly(1-methylpentyldiallylamine), poly(2-methylpentyldiallylamine), poly(3-methylpentyldiallylamine), poly(4-methylpentyldiallylamine), poly(1,1-dimethyl-butyldiallylamine), poly(1,2-dimethyl-butyldiallylamine), poly(1,3-dimethyl-butyldiallylamine), poly(2,2-dimethyl-butyldiallylamine), poly(2,3-dimethyl-butyldiallylamine), poly(1,1-dimethyl-2-methyl-propyldiallylamine), poly(1-dimethyl-2,2-dimethyl-propyl diallylamine), poly(cyclohexyl diallylamine), poly(heptyl diallylamine), poly(octyl diallylamine), poly(nonyl diallylamine), poly(decyl diallylamine), poly(dipropyl diallyl ammonium chloride), poly(bis(iso-propyl) diallyl ammonium chloride), poly(dibutyl diallyl ammonium chloride), poly(bis(iso-butyl) diallyl ammonium chloride), poly(bis(tert-butyl) diallyl ammonium chloride), poly(bis(sec-butyl) diallyl ammonium chloride), poly(dipentyl diallyl ammonium chloride), poly(bis(isopentyl) diallyl ammonium chloride), poly(bis(1-methylbutyl) diallyl ammonium chloride), poly(bis(1,1-dimethylpropyl) diallyl ammonium chloride), poly(bis(2,2-dimethylpropyl) diallyl ammonium chloride), poly(bis(1,2-dimethyl-butyl)diallyl ammonium chloride), poly(bis(1,3-dimethyl-butyl)diallyl ammonium chloride), poly(bis(2,2-dimethyl-butyl)diallyl ammonium chloride), poly(bis(2,3-dimethyl-butyl)diallyl ammonium chloride), poly(bis(1,1-dimethyl-2-methyl-propyl)diallyl ammonium chloride), poly(bis(1-dimethyl-2,2-dimethyl-propyl) diallyl ammonium chloride), poly(dicyclohexyl diallyl ammonium chloride), poly(diheptyl diallyl ammonium chloride), poly(dioctyl diallyl ammonium chloride), poly(dinonyl diallyl ammonium chloride), poly(didecyl diallyl ammonium chloride), allylamine diallylamine copolymer, allylamine diallyl dimethyl ammonium chloride copolymer, diallylamine hydrochloride sulfur dioxide copolymer, diallyl methylethyl ammonium sulfate sulfur dioxide copolymer, methyl diallylamine sulfur dioxide copolymer, diallyl dimethyl ammonium chloride sulfur dioxide copolymer, diallylamine hydrochloride acrylamide copolymer, diallyl dimethyl ammonium chloride acrylamide copolymer, methyl diallylamine diallyl dimethyl ammonium chloride copolymer, epichlorohydrin addition type tertiary amine hydrochloride quaternary ammonium salt copolymer, diallylamine hydrochloride maleic acid copolymer, methyl diallylamine Examples of the copolymers include diallylamine maleic acid copolymer, diallylmethylethylammonium ethylsulfate maleic acid copolymer, and diallylmethylethylammonium chloride maleic acid copolymer. Specific products include, for example, Unisense FPA100L, PAS-21CL, PAS-21, PAS-M-1L, PAS-M-1, PAS-22SA-40, PAS-M-1A, PAS-H-1L, PAS-H-1LL, PAS-H-5L, PAS-H-10L, PAS-24, and PAS-92. , PAS-2401, PAS-92A, PAS-2201, PAS-2201CL, PAS-2201A, PAS-A-1, PAS-A-5, PAS-2141CL, PAS-J-81L, PAS-J-81, PAS-J-81LL, PAS-J-4 1, PAS-J-41H, PAS-2223, PAS-880, PAS-410C, PAS-411C, PAS-410L, PAS-410SA, PAS-2251, PAS-84, PAS-2451, or PAS-2351. ,

[0042] The polydiallylamine (B) has an average molecular weight of preferably 1,000 to 500,000, and more preferably 5,000 to 200,000, in view of its excellent ability to simultaneously remove zinc and nickel.

[0043] In the wastewater treatment agent of the present invention, the content of the polydiallylamine (B) is 0.1 to 300 parts by mass relative to 100 parts by mass of the inorganic sulfide (A). In terms of excellent simultaneous removal of zinc and nickel, the content is preferably 0.5 to 200 parts by mass, and more preferably 1 to 100 parts by mass.

[0044] The organic amine compound (C) having at least three carboxy groups and one hydroxy group is not particularly limited, and examples thereof include hydroxyiminodisuccinic acid (HIDS), 1,3-diamino-2-hydroxypropane-N,N,N',N'-tetraacetic acid (DPTA), N-(2-hydroxyethyl)ethylenediaminetriacetic acid (HEDTA), and alkali metal salts thereof (e.g., hydroxyiminodisuccinic acid tetrasodium salt, 1,3-diamino-2-hydroxypropane-N,N,N',N'-tetraacetic acid tetrasodium salt, and N-(2-hydroxyethyl)ethylenediaminetriacetic acid trisodium salt, etc.).

[0045] The alkali metal in the alkali metal salt is not particularly limited, but examples thereof include lithium, sodium, and potassium.

[0046] As the organic amine compound (C), from the viewpoint of being excellent in simultaneous removal of zinc and nickel, hydroxyiminodisuccinic acid (HIDS), tetrasodium hydroxyiminodisuccinic acid, diaminohydroxypropane tetraacetic acid, tetrasodium diaminohydroxypropane tetraacetate, hydroxyethylethylenediaminetriacetic acid, or trisodium hydroxyethylethylenediaminetriacetate is preferred, and tetrasodium hydroxyiminodisuccinic acid, diaminohydroxypropane tetraacetic acid, or hydroxyethylethylenediaminetriacetic acid is more preferred.

[0047] In the wastewater treatment agent of the present invention, the content of the organic amine compound (C) having at least three carboxy groups and one hydroxy group is 0.2 to 2.5 parts by mass relative to 100 parts by mass of the inorganic sulfide (A), and is preferably 0.5 to 1.5 parts by mass in terms of excellent simultaneous removal of zinc and nickel.

[0048] The wastewater treatment agent of the present invention may further contain a compound (D) having a dithiocarbamic acid group. The content of the compound (D) is preferably 1 to 200 parts by mass, and more preferably 5 to 100 parts by mass, per 100 parts by mass of the inorganic sulfide (A).

[0049] The compound (D) having a dithiocarbamic acid group is not particularly limited as long as it is a compound having a dithiocarbamyl group in the molecule.

[0050] An example of the compound (D) having a dithiocarbamic acid group is a compound obtained by reacting an amine compound having at least one amino group selected from the group consisting of a primary amino group and a secondary amino group, carbon disulfide, and an alkali metal hydroxide.

[0051] Specific examples of the amine compound having at least one amino group selected from the group consisting of a primary amino group and a secondary amino group include dimethylamine, diethylamine, dipropylamine, dibutylamine, diisobutylamine, di-sec-butylamine, di-tert-butylamine, dipentylamine, di(isopentyl)amine, di(1-methylbutyl)amine, di(1-ethylpropyl)amine, di(1,1-dimethylpropyl)amine, di(2,2-dimethylpropyl)amine, dihexylamine, and the like. di(1-methylpentyl)amine, di(2-methylpentyl)amine, di(3-methylpentyl)amine, di(4-methylpentyl)amine, di(1,1-dimethyl-butyl)amine, di(1,2-dimethyl-butyl)amine, di(1,3-dimethyl-butyl)amine, di(2,2-dimethyl-butyl)amine, di(2,3-dimethyl-butyl)amine, di(1,1-dimethyl-2-methyl-propyl)amine, di(1,1-dimethyl-2,2-dimethyl-propyl)amine, diheptylamine, ethylamine, dioctylamine, dinonylamine, didecylamine, butylmethylamine, N-methylhexylamine, N-ethylisoamylamine, N-methylethylamine, N-methylisopropylamine, N-ethylbutylamine, N,N'-di-tert-butylethylenediamine, 3,3'-iminobis(propylamine), N,N'-bis(3-aminopropyl)-1,3-propanediamine, N,N'-bis(3-aminopropyl)tetramethylenediamine, N-ethylphenyl Amines, aziridine, azetidine, pyrrolidine, piperidine, 2-methylpiperidine, 3-methylpiperidine, 4-methylpiperidine, 2,4-dimethylpiperidine, 2,6-dimethylpiperidine, 3,5-dimethylpiperidine, 3-piperidinemethanol, 4-piperidinemethanol, 2-piperidineethanol, 4-piperidineethanol, 4-hydroxypiperidine, 2-(aminomethyl)piperidine, 4-(aminomethyl)piperidine, 4-(dimethylamino)piperidine, 2,2,6,6-Tetramethylpiperidine, 4-piperidinopiperidine, dibenzylamine, hexamethyleneimine, heptamethyleneimine, 3-aminopyrrolidine, pyrrole, piperazine, N-methylpiperazine, N-ethylpiperazine, N-isobutylpiperazine, N-isobutylpiperazine, 1-cyclopentylpiperazine, 1-(2-pyridyl)piperazine, 1-(4-pyridyl)piperazine, 1-(2-pyrimidyl)piperazine, 2-methylpiperazine, cis- Examples of the polyamine include 2,6-dimethylpiperazine, 2,5-dimethylpiperazine, 2-aminomethylpiperazine, homopiperazine, N-methylhomopiperazine, N-ethylcyclohexylamine, diethylenetriamine, N-(2-aminoethyl)piperazine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, heptaethyleneoctamine, polyethyleneimine, and a condensate of polyethyleneimine, sodium hydroxide, and benzyl chloride.

[0052] As the compound (D) having a dithiocarbamic acid group, from the viewpoint of being excellent in simultaneous removal of zinc and nickel, preferred are compounds obtained by reacting dimethylamine, diethylamine, piperazine, tetraethylenepentamine, pyrrolidine, or piperidine with carbon disulfide and an alkali metal hydroxide or an alkaline earth metal hydroxide, and more preferred are compounds obtained by reacting piperazine with carbon disulfide and an alkali metal hydroxide.

[0053] The alkali metal hydroxide is not particularly limited, but may be, for example, lithium hydroxide, sodium hydroxide, or potassium hydroxide. The alkaline earth metal hydroxide is not particularly limited, but may be, for example, magnesium hydroxide or calcium hydroxide.

[0054] As the compound (D) having a dithiocarbamic acid group, a compound obtained by reacting with an alkali metal hydroxide is preferred, and a compound obtained by reacting with sodium hydroxide or potassium hydroxide is more preferred, in that the solubility of the dithiocarbamic acid salt is excellent.

[0055] Examples of the compound (D) having a dithiocarbamic acid group include lithium dimethyldithiocarbamate, sodium dimethyldithiocarbamate, potassium dimethyldithiocarbamate, lithium diethylaminodithiocarbamate, sodium diethylaminodithiocarbamate, potassium diethylaminodithiocarbamate, piperazine-1,4-bis(lithium dithiocarboxylate), piperazine-1,4-bis(sodium dithiocarboxylate), and piperazine-1,4-bis(potassium dithiocarboxylate).

[0056] The compound (D) having a dithiocarbamic acid group is preferably one or more selected from the group consisting of sodium dimethyldithiocarbamate, potassium dimethyldithiocarbamate, piperazine-1,4-bis(sodium dithiocarboxylate), and piperazine-1,4-bis(potassium dithiocarboxylate), because they are excellent in simultaneous removal of zinc and nickel.

[0057] The wastewater treatment agent of the present invention may further contain water. When water is contained, the content of water is preferably 50 to 95 mass%, and more preferably 60 to 90 mass%, based on 100 mass% of the wastewater treatment agent including water.

[0058] The content of the water is preferably 100 to 5,000 parts by mass, and more preferably 200 to 4,000 parts by mass, relative to 100 parts by mass of the inorganic sulfide (A).

[0059] The wastewater treatment agent of the present invention may contain components not described above.

[0060] Another embodiment of the present invention is a wastewater treatment method (wastewater treatment method A), which is characterized by adding the wastewater treatment agent of the present invention to wastewater containing a carboxylic acid compound, zinc, and nickel, stirring the mixture, then adding a polymer flocculant and stirring the mixture to form a slurry, and then separating a solid component from the slurry.

[0061] The wastewater containing the carboxylic acid compound, zinc, and nickel (hereinafter referred to as "the wastewater") will be described.

[0062] An example of this type of wastewater is that discharged from a plating wastewater treatment facility for printed circuit boards, etc.

[0063] The wastewater may contain, but is not limited to, metals other than zinc and nickel, such as cadmium, chromium, copper, iron, mercury, lead, palladium, gold, silver, platinum, cobalt, indium, molybdenum, antimony, tin, titanium, zirconium, manganese, and tungsten.

[0064] These metals are contained in the wastewater in various forms, such as metal ions, metal complexes, or metal salts, but the forms change easily depending on various factors, such as pH, temperature, metal concentration, type of carboxylic acid compound, or concentration of carboxylic acid compound, etc. For this reason, it is not realistic to specifically and precisely determine all forms of all metals.

[0065] The wastewater treatment agent of the present invention can be applied to such wastewater containing metals other than zinc and nickel, and can effectively reduce the concentrations of zinc and nickel in the wastewater.

[0066] The carboxylic acid compound is not particularly limited, and examples thereof include formic acid, acetic acid, lactic acid, tartaric acid, citric acid, succinic acid, oxalic acid, ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid, acrylic acid, gluconic acid, malonic acid, glutaric acid, adipic acid, malic acid, glycolic acid, ascorbic acid, hydroxybutyric acid, glucoheptonic acid, citramalic acid, erythorbic acid, glutamic acid, dicarboxymethylglutamic acid, ornithine, cysteine, glycine, N,N-bis(2-hydroxyethyl)glycine, and (S,S)-ethylenediaminesuccinic acid. In particular, examples of carboxylic acid compounds that form strong complexes with zinc or nickel include lactic acid, tartaric acid, citric acid, and EDTA, and the treatment of wastewater containing these carboxylic acid compounds is preferred.

[0067] The zinc concentration in the wastewater is not particularly limited, but from the viewpoint of excellent simultaneous removal of zinc and nickel, it is preferably 2 to 1,000 mg / L, more preferably 10 to 700 mg / L, and even more preferably 20 to 500 mg / L.

[0068] In addition, the nickel concentration in the wastewater is not particularly limited, but from the viewpoint of excellent simultaneous removal of zinc and nickel, it is preferably 2 to 1,000 mg / L, more preferably 10 to 700 mg / L, and even more preferably 20 to 500 mg / L.

[0069] Regarding the ratio of the zinc and nickel contents in the wastewater, it is preferable that the nickel content be 0.1 mole or more per mole of zinc (9 parts by mass or more of nickel per 100 parts by mass of zinc) and 10 moles or less, in terms of excellent simultaneous removal of zinc and nickel.

[0070] In the present wastewater, the concentration of the carboxylic acid compound is not particularly limited, but is preferably 1 to 500 mg / L, and more preferably 5 to 200 mg / L, from the viewpoint of excellent simultaneous removal of zinc and nickel.

[0071] In the present wastewater, the ratio of the carboxylic acid compound to zinc ions (moles of carboxylic acid compound ÷ moles of zinc ions (mol / mol)) is not particularly limited, but is preferably 0.1 to 2 (mol / mol), and more preferably 0.2 to 1 (mol / mol), in terms of excellent simultaneous removal of zinc and nickel.

[0072] When the wastewater treatment agent is added to the main wastewater, the pH of the main wastewater is preferably 6 to 14, and more preferably 8 to 11, before and after the addition of the wastewater treatment agent, etc., from the viewpoints of being able to suppress the generation of hydrogen sulfide gas accompanying the decomposition of inorganic sulfides and of being excellent in the simultaneous removal of zinc and nickel.

[0073] If the pH of the wastewater is outside the above-mentioned preferred range, it is preferable to adjust the pH to within the above-mentioned preferred range using an acid or a base.

[0074] The acid used in this case is not particularly limited, but examples thereof include hydrochloric acid, ammonium chloride, sulfuric acid, ammonium bisulfate, nitric acid, phosphoric acid, boric acid, polyphosphoric acid, iron chloride, and iron sulfate.

[0075] The base used in this case is not particularly limited, but examples thereof include caustic soda, caustic potassium, sodium bicarbonate, potassium bicarbonate, calcium carbonate, quicklime, and hydrated lime.

[0076] The amount of the wastewater treatment agent added to the main wastewater is preferably 10 to 5,000 mg, more preferably 50 to 3,000 mg, and even more preferably 100 to 2,000 mg per 1 L of the main wastewater, in terms of excellent simultaneous removal of zinc and nickel.

[0077] With regard to the amount of the wastewater treatment agent to be added, in view of its excellent ability to simultaneously remove zinc and nickel, it is preferable to adjust the amount of inorganic sulfide in the wastewater treatment agent to 0.1 to 20 moles per mole of zinc ion contained in the main wastewater, more preferably to adjust the amount to 0.5 to 15 moles, and even more preferably to adjust the amount to 1 to 10 moles.

[0078] It is preferable to stir the main wastewater after adding the wastewater treatment agent to the main wastewater, and the stirring time is usually preferably within a range of several minutes to 2 hours.

[0079] The wastewater treatment method A of the present invention is characterized in that after the wastewater treatment agent is added to the main wastewater, a polymer flocculant is further added, and by adding the polymer flocculant, a slurry that is easy to filter can be formed. The slurry contains the zinc, the nickel, the inorganic sulfide (A), the polydiallylamine (B), the organic amine compound (C), the compound having a dithiocarbamic acid group (D), and a solid precipitated by reaction with the polymer flocculant.

[0080] By carrying out the above wastewater treatment method A, zinc and nickel dissolved in the wastewater are insolubilized, making it possible to remove zinc and nickel from the wastewater.

[0081] The polymer flocculant is not particularly limited, but may be, for example, an acrylic acid polymer, an acrylamide polymer, or a dimethylaminoethyl methacrylate polymer. Among these, an acrylic acid polymer is preferred because it is excellent in simultaneous removal of zinc and nickel. It is preferred to use commercially available products of these polymer flocculants as they are.

[0082] The amount of the polymer flocculant to be added is not particularly limited, but from the viewpoint of being excellent in simultaneous removal of zinc and nickel, it is preferably 0.1 to 10 parts by mass, and more preferably 0.1 to 5 parts by mass, based on 100 parts by mass of zinc contained in the main wastewater.

[0083] It is preferable to stir the wastewater after the addition of the polymer flocculant, and the stirring time is usually selected from the range of several minutes to 2 hours.

[0084] By adding the polymer flocculant, a slurry that is easy to filter can be obtained. In addition, by further adding a flocculant other than the polymer flocculant, the slurry can be made even easier to filter.

[0085] The flocculant is not particularly limited, and examples thereof include iron compounds such as ferric chloride or ferrous sulfate, and aluminum compounds such as aluminum sulfate or polyaluminum chloride, etc. However, the use of such inorganic flocculants increases the amount of heavy metal-containing sludge, which increases the transportation costs when transporting the sludge to a landfill site, so it is preferable to use as little as possible.

[0086] The method for separating the solid components from the slurry is not particularly limited, but examples thereof include filtration, centrifugation, or a method in which the solid components are allowed to settle and then separated from the supernatant (sedimentation separation).

[0087] The wastewater treatment method A of the present invention may be carried out under any of cooling conditions, room temperature conditions, ambient temperature conditions, and heated conditions, and the temperature of the wastewater, the temperature of the wastewater during the process of adding the wastewater treatment agent, and the temperature of the wastewater during the process of adding an additional amount of polymer flocculant are each independently preferably in the range of -10°C to 80°C, and more preferably in the range of 4°C to 40°C.

[0088] The wastewater treatment method A of the present invention may be carried out in a continuous manner or a single-phase (batchwise) manner.

[0089] As another embodiment of the present invention, there is mentioned a wastewater treatment method (wastewater treatment method B), which is characterized by adding the inorganic sulfide (A), the polydiallylamine (B), and the organic amine compound (C) to the main wastewater and stirring the mixture, then adding a polymer flocculant and stirring the mixture to form a slurry, and then separating a solid component from the slurry.

[0090] In the wastewater treatment method B, in addition to the above-mentioned (A), (B), and (C), a compound (D) having a dithiocarbamic acid group may be further added.

[0091] The wastewater, inorganic sulfide (A), polydiallylamine (B), organic amine compound (C), compound having a dithiocarbamic acid group (D), polymer flocculant, or flocculant used in the wastewater treatment method B are as described above.

[0092] The addition method, stirring method, separation method, treatment conditions, etc. in the wastewater treatment method B are also as described above (similar to the wastewater treatment method A).

[0093] In the wastewater treatment method B, the amount of the inorganic sulfide (A) added is preferably 0.1 to 20 mol, more preferably 0.5 to 15 mol, and still more preferably 1 to 10 mol, per mol of zinc ions contained in the wastewater, from the viewpoint of being excellent in simultaneous removal of zinc and nickel.

[0094] In the wastewater treatment method B, the amount of the polydiallylamine (B) added is preferably 0.1 to 300 parts by mass, more preferably 0.5 to 200 parts by mass, and still more preferably 1 to 100 parts by mass, relative to 100 parts by mass of the inorganic sulfide (A) added, in that the polydiallylamine (B) is excellent in simultaneous removal of zinc and nickel.

[0095] In the wastewater treatment method B, the amount of the organic amine compound (C) added is preferably 0.2 to 2.5 parts by mass, and more preferably 0.5 to 1.5 parts by mass, relative to 100 parts by mass of the inorganic sulfide (A) added, in that the organic amine compound (C) is excellent in simultaneous removal of zinc and nickel.

[0096] In the wastewater treatment method B, when the compound (D) having a dithiocarbamic acid group is used, the amount of the compound (D) added is preferably 1 to 200 parts by mass, and more preferably 5 to 100 parts by mass, per 100 parts by mass of the inorganic sulfide (A) added, in terms of excellent simultaneous removal of zinc and nickel.

[0097] In the wastewater treatment method B, examples of the method of adding the inorganic sulfide (A), the polydiallylamine (B), and the organic amine compound (C) to the main wastewater include a method of separately adding each solid substance to the main wastewater, a method of adding a solid material obtained by mixing the inorganic sulfide (A), the polydiallylamine (B), and the organic amine compound (C) to the main wastewater, a method of separately adding each aqueous solution to the main wastewater, and a method of adding an aqueous solution in which the three types of the inorganic sulfide (A), the polydiallylamine (B), and the organic amine compound (C) are dissolved to the main wastewater. From the viewpoint of excellent operability, however, the method of adding an aqueous solution in which the three types of the inorganic sulfide (A), the polydiallylamine (B), and the organic amine compound (C) are dissolved to the main wastewater is preferred.

[0098] In addition, in the case where the compound (D) having a dithiocarbamic acid group is used, examples of the method of adding the inorganic sulfide (A), the polydiallylamine (B), the organic amine compound (C), and the compound (D) having a dithiocarbamic acid group to wastewater (main wastewater) containing carboxylic acid, zinc, and nickel in the wastewater treatment method B include a method of separately adding each solid substance to the main wastewater, a method of adding the inorganic sulfide (A), the polydiallylamine (B), the organic amine compound (C), and the compound (D) having a dithiocarbamic acid group to the main wastewater, and a method of adding the inorganic sulfide (A), the polydiallylamine (B), the organic amine compound (C), and the compound (D) having a dithiocarbamic acid group to the main wastewater. a method of adding a solid mixture of the inorganic sulfide (A), the polydiallylamine (B), the organic amine compound (C), and the compound having a dithiocarbamic acid group (D) to the main wastewater, respectively; and a method of adding an aqueous solution of the inorganic sulfide (A), the polydiallylamine (B), the organic amine compound (C), and the compound having a dithiocarbamic acid group (D) to the main wastewater, respectively, from the viewpoint of ease of operation, the method of adding an aqueous solution of the inorganic sulfide (A), the polydiallylamine (B), the organic amine compound (C), and the compound having a dithiocarbamic acid group (D) to the main wastewater is preferred.

[0099] In the wastewater treatment method B, the method for separating the solid components from the slurry is not particularly limited, and examples thereof include filtration, centrifugation, or a method in which the solid components are allowed to settle and then separated from the supernatant liquid (sedimentation separation). EXAMPLES

[0100] The present invention will be described in detail below, but the present invention should not be construed as being limited to these examples.

[0101] (Analysis method) The heavy metal ion concentrations in the aqueous solutions were measured using an ICP emission spectrometer (ICPE-9800, manufactured by Shimadzu Corporation).

[0102] [Inorganic sulfide (A)] The following inorganic sulfides were used:

[0103] Sodium hydrogen sulfide (manufactured by Fujifilm Wako Pure Chemical Industries, hereafter referred to as NaSH) Potassium sulfide (FUJIFILM Wako Pure Chemical Industries, Ltd., hereafter referred to as K2S) Calcium polysulfide (Sakura Kako Co., Ltd., lime sulfur mixture, hereafter referred to as Ca polysulfide) [Polydiallylamine (B)] The following was used as polydiallylamine (B) (hereinafter abbreviated as PDAA).

[0104] Diallylamine polymer (average molecular weight 5,000) (manufactured by Nittobo Medical Co., Ltd., PAS-21) (hereinafter abbreviated as PDAA-1).

[0105] Diallyldimethylammonium chloride polymer (average molecular weight 8,500) (manufactured by Nittobo Medical Co., Ltd., PAS-H-1L) (hereinafter abbreviated as PDAA-2).

[0106] Diallyldimethylammonium chloride polymer (average molecular weight 30,000) (manufactured by Nittobo Medical Co., Ltd., PAS-H-5L) (hereinafter abbreviated as PDAA-3).

[0107] Diallyldimethylammonium chloride polymer (average molecular weight 200,000) (manufactured by Nittobo Medical Co., Ltd., PAS-H-10L) (hereinafter abbreviated as PDAA-4).

[0108] Diallyl methylethyl ammonium ethyl sulfate polymer (average molecular weight 37,000) (manufactured by Nittobo Medical Co., Ltd., PAS-24) (hereinafter abbreviated as PDAA-5).

[0109] Methyldiallylamine hydrochloride polymer (average molecular weight 5,000) (manufactured by Nittobo Medical Co., Ltd., PAS-M-1L) (hereinafter abbreviated as PDAA-6).

[0110] Methyldiallylamine hydrochloride polymer (average molecular weight 20,000) (manufactured by Nittobo Medical Co., Ltd., PAS-M-1) (hereinafter abbreviated as PDAA-7).

[0111] Methyldiallylamine acetate polymer (average molecular weight 20,000) (manufactured by Nittobo Medical Co., Ltd., PAS-M-1A) (hereinafter abbreviated as PDAA-8).

[0112] Methyldiallylamine amidosulfate polymer (average molecular weight 15,000) (manufactured by Nittobo Medical Co., Ltd., PAS-22SA-40) (hereinafter abbreviated as PDAA-9).

[0113] Methyldiallylamine diallyldimethylammonium chloride polymer (average molecular weight 13,000) (manufactured by Nittobo Medical Co., Ltd., PAS-2223) (hereinafter abbreviated as PDAA-10).

[0114] The structures of PDAA-1 to PDAA-10 are shown in Table 1.

[0115] [Table 1]

[0116] In the comparative examples, the following substances were used as similar substances to the above (B).

[0117] Polyethyleneimine (average molecular weight 1800) (manufactured by Nippon Shokubai Co., Ltd., hereinafter abbreviated as PEI(1800)).

[0118] Polyethyleneimine (average molecular weight 750,000) (manufactured by BASF, hereafter abbreviated as PEI (750,000)).

[0119] Di-n-alkyldimethylammonium chloride (mixture) (manufactured by Tokyo Chemical Industry Co., Ltd., hereinafter abbreviated as DADMe).

[0120] Copolymer of acrylamide · acrylonitrile · N(2)-vinylacrylamidine-hydrogen chloride (1 / 1) · N-vinylacrylamide · vinylamine-hydrogen chloride (1 / 1) · N-vinylformamide (molecular weight 3,000,000) (manufactured by Mitsubishi Chemical Corporation, Diaflock KP7000, hereafter abbreviated as AVVV).

[0121] [Organic amine compound (C) having at least three carboxy groups and one hydroxy group] The following organic amine compounds (C) having at least three carboxy groups and one hydroxy group (hereafter abbreviated as HACA) were used. In addition, the following examples of similar substances to (C) that do not fall under the above category are also shown below.

[0122] Tetrasodium hydroxyiminodisuccinate (manufactured by Nagase ChemteX Corporation, hereinafter abbreviated as HIDS4Na).

[0123] Diaminohydroxypropanetetraacetic acid (Tokyo Chemical Industry Co., Ltd., hereafter abbreviated as DPTA) Hydroxyethylethylenediaminetriacetate trisodium (Tokyo Chemical Industry Co., Ltd., hereinafter abbreviated as HEDTA).

[0124] In the comparative examples, the following substances were used as similar substances to the above (C).

[0125] Ethylenediamine-N,N,N',N'-tetraacetic acid tetrasodium salt (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., hereafter abbreviated as EDTA4Na).

[0126] Tetrasodium glutamic acid diacetate (Tokyo Chemical Industry Co., Ltd., hereafter abbreviated as GLDA4Na) Nitrilotriacetic acid (Tokyo Chemical Industry Co., Ltd., hereafter abbreviated as NTA) Disodium hydroxyethyliminodiacetate (Tokyo Chemical Industry Co., Ltd., hereafter abbreviated as HIDA2Na) Dihydroxyethylglycine (Tokyo Chemical Industry Co., Ltd., hereafter abbreviated as DHEG) The structures of the above compounds are shown in Table 2.

[0127] [Table 2]

[0128] [Compound (D) having a dithiocarbamic acid group] As the compound (D) having a dithiocarbamic acid group, the following was used.

[0129] Piperazine dithiocarbamic acid potassium salt (hereinafter referred to as PIP-DTC) Tetraethylenepentamine dithiocarbamic acid sodium salt (hereinafter referred to as TEPA-DTC) Sodium dimethyldithiocarbamate dihydrate (DMe-DTC) Diethyldithiocarbamic acid sodium salt (hereinafter referred to as DEt-DTC) Ammonium pyrrolidine dithiocarbamate (hereinafter referred to as APDC) Piperidinedithiocarbamic acid piperidine salt (hereinafter referred to as PPDC) PIP-DTC was prepared according to the following method.

[0130] After mixing 112 g of piperazine (manufactured by Tosoh Corporation) and 386 g of pure water, 306 g of 48% by weight potassium hydroxide (manufactured by Kishida Chemical Co., Ltd.) and 196 g of carbon disulfide (manufactured by Kishida Chemical Co., Ltd.) were alternately dropped in four portions at 25° C. under stirring in a nitrogen stream. After stirring for one hour, an aqueous solution containing 40% by mass of PIP-DTC was obtained.

[0131] [ka]

[0132] TEPA-DTC was prepared according to the following method.

[0133] After mixing 159 g of tetraethylenepentamine (manufactured by Tosoh Corporation) and 331 g of pure water, 281 g of 48% by weight sodium hydroxide (manufactured by Kishida Chemical Co., Ltd.) and 230 g of carbon disulfide (manufactured by Kishida Chemical Co., Ltd.) were alternately dropped in four portions at 25° C. under stirring in a nitrogen stream. After stirring for one hour, an aqueous solution containing 40% by mass of TEPA-DTC was obtained.

[0134] [ka]

[0135] 25.0 g of sodium dimethyldithiocarbamate dihydrate (Tokyo Chemical Industry Co., Ltd.) and 25.0 g of pure water were mixed and then stirred at 25° C. for 10 minutes to obtain an aqueous solution containing 40 mass % DMe-DTC.

[0136] [ka]

[0137] 26.3 g of sodium N,N-diethyldithiocarbamate trihydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 23.7 g of pure water were mixed and then stirred at 25° C. for 10 minutes to obtain an aqueous solution containing 40 mass % DEt-DTC.

[0138] [ka]

[0139] 20.0 g of ammonium 1-pyrrolidinecarbodithioate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 30.0 g of pure water were mixed and then stirred at 25° C. for 10 minutes to obtain an aqueous solution containing 40% by mass of APDC.

[0140] [ka]

[0141] 20.0 g of piperidinium pentamethylene dithiocarbamate (Tokyo Chemical Industry Co., Ltd.) and 30.0 g of water were mixed and then stirred at 25° C. for 10 minutes to obtain a solution containing 40% by mass of PPDC.

[0142] [ka]

[0143] [Polymer flocculant] OA-23 (Organo Corporation, weak anionic polymer) was used as the polymer flocculant.

[0144] Example 1 300 mL of an aqueous solution (wastewater composition) containing 50 mg / L zinc ions, 50 mg / L nickel ions, and 80 mg / L citric acid (corresponding to the carboxylic acid compound of this wastewater) was added to a 500 mL beaker placed in a jar tester. Next, while stirring at 150 rpm, a 10% aqueous sodium hydroxide solution was added to adjust the pH of the wastewater composition to 9. In the wastewater composition, the molar ratio of the carboxylic acid compound to the zinc ion (moles of the carboxylic acid compound ÷ moles of the zinc ion) was 0.54 (mol / mol).

[0145] Next, 18 mg of NaSH (addition amount 60 mg / L (wastewater composition)) was added as the inorganic sulfide (A), 11 mg of PDAA-1 (addition amount 36 mg / L (wastewater composition)) was added as the polydiallylamine (B), and 0.18 mg of HIDS4Na (addition amount 0.6 mg / L (wastewater composition)) was added as the organic amine compound (C) to the wastewater composition, and the mixture was stirred at 150 rpm for 5 minutes.

[0146] Next, 0.6 mg (addition amount 2 mg / L (wastewater composition)) of OA-23 was added as a polymer flocculant, and the mixture was stirred at 50 rpm for 5 minutes.

[0147] After stopping the stirring and leaving it to stand for 5 minutes, the resulting slurry was separated into a solid component and a supernatant component, and the wastewater treatment method of the present invention was carried out. The concentrations of zinc and nickel remaining in the supernatant component were measured. The results are shown in Table 3.

[0148] Examples 2 to 17, Comparative Examples 1 to 29 The same operations as in Example 1 were carried out (the wastewater treatment method of the present invention was carried out) except that the type and amount of inorganic sulfide (A), the type and amount of polydiallylamine (B), and the type and amount of organic amine compound (C) having at least three carboxy groups and one hydroxy group were changed to those shown in Examples 2 to 17 and Comparative Examples 1 to 27 in Table 3. The results are shown in Tables 3 and 4.

[0149] In Comparative Examples 10 to 17, no inorganic sulfide (A) was used. Instead, 24 mg of a compound (D) having a dithiocarbamic acid group shown in Table 4 was used as a solid content (amount added: 60 mg / L (wastewater composition)) (150 mg / L (wastewater composition) as an aqueous solution containing 40 mass% of a compound (D) having a dithiocarbamic acid group).

[0150] [Table 3]

[0151] [Table 4]

[0152] Examples 1 to 17 are examples in which the wastewater treatment method of the present invention was carried out, and show that zinc and nickel can be treated simultaneously regardless of the types of inorganic sulfide (A), polydiallylamine (B), and organic amine compound (C).

[0153] Comparative Examples 1 to 3 are examples lacking the polydiallylamine (B) and the organic amine compound (C), but were unable to reduce zinc and nickel.

[0154] Comparative Examples 4 to 6 are examples lacking the inorganic sulfide (A) and the organic amine compound (C), and the zinc and nickel treatment performance was insufficient.

[0155] Comparative Examples 7 to 9 are examples lacking the inorganic sulfide (A) and the polydiallylamine (B), but were unable to reduce zinc and nickel.

[0156] Comparative Examples 10 to 17 are examples in which the inorganic sulfide (A) was omitted and instead, a compound (D) having a dithiocarbamic acid group was used for treatment, but zinc and nickel could not be reduced.

[0157] Comparative Examples 18 to 21 are examples that lacked the polydiallylamine (B) of the present invention and used a polyamine that does not correspond to the polydiallylamine (B), and the zinc and nickel treatment performance was insufficient.

[0158] Comparative Examples 22 to 26 are examples that did not contain the organic amine compound (C) of the present invention and used aminocarboxylic acids that do not fall under the organic amine compound (C), and the treatment performance for zinc and nickel was insufficient.

[0159] Comparative Example 27 is an example lacking the organic amine compound (C), and the treatment performance for zinc and nickel was insufficient.

[0160] Comparative Example 28 is an example in which polydiallylamine (B) was not contained and an aminocarboxylic acid not corresponding to the organic amine compound (C) was used, but zinc and nickel could not be reduced.

[0161] Comparative Example 29 is an example in which an inorganic sulfide (A) was not contained and an aminocarboxylic acid not corresponding to the organic amine compound (C) was used, and the treatment performance for zinc and nickel was insufficient.

[0162] Example 18 In a 200 mL beaker, 40.0 g of 15 mass% PDAA-1 aqueous solution as polydiallylamine (B), 0.2 g of 50 mass% HIDS4Na aqueous solution as organic amine compound (C), and 32.6 g of water were added and stirred, and then 5.0 g of 20 mass% sodium hydroxide aqueous solution was added. Next, 22.2 g of 45 mass% NaSH aqueous solution as inorganic sulfide (A) was added, and the mixture was stirred for 30 minutes to obtain 100 g of wastewater treatment agent A corresponding to the wastewater treatment agent of the present invention.

[0163] The composition of the wastewater treatment agent A is NaSH (corresponding to inorganic sulfide (A)) / PDAA-1 (corresponding to polydiallylamine (B)) / HIDS4Na (corresponding to organic amine compound (C)) / sodium hydroxide / water = 9.99 / 6 / 0.1 / 1 / 82.91 (all by mass).

[0164] 300 mL of an aqueous solution (wastewater composition) containing 50 mg / L zinc ions, 50 mg / L nickel ions, and 80 mg / L citric acid was added to a 500 mL beaker placed in a jar tester. Next, the pH of the wastewater composition was adjusted to 9 with a 10% aqueous sodium hydroxide solution while stirring at 150 rpm.

[0165] Next, 180 mg of the wastewater treatment agent A was added (so that the input amount was 600 mg / L (wastewater composition)) and stirred at 150 rpm for 5 minutes. Next, 0.6 mg of OA-23 was added as a polymer flocculant (so that the input amount was 2 mg / L (wastewater composition)) and stirred at 50 rpm for 5 minutes. After stopping the stirring and leaving it to stand for 5 minutes, the resulting slurry was separated into a solid component and a supernatant component, thereby carrying out the wastewater treatment method of the present invention. The concentrations of zinc and nickel remaining in the supernatant component were measured. The results are shown in Table 6.

[0166] Examples 19 to 23, 26 to 30, and 33 The same procedure as in Example 18 was carried out, except that PDAA-1 and HIDS4Na were changed to those shown in Table 4, to obtain 100 g of wastewater treatment agents B to F, I to M, and P. The compositions of the wastewater treatment agents B to F, I to M, and P are shown in Table 4. The evaluation results of the wastewater treatment agents are shown in Table 6.

[0167] Example 24 In a 200mL beaker, 20.0g of 15% by mass PDAA-3 aqueous solution, 0.2g of 50% by mass HIDS4Na aqueous solution, and 52.6g of water were added, stirred, and then 5.0g of 20% by mass sodium hydroxide aqueous solution was added. Next, 22.2g of 45% by mass NaSH aqueous solution was added, and stirred for 30 minutes to obtain 100g of wastewater treatment agent G, which corresponds to the wastewater treatment agent of the present invention. The composition of the wastewater treatment agent G is shown in Table 4.

[0168] 300 mL of an aqueous solution (wastewater composition) containing 50 mg / L zinc ions, 50 mg / L nickel ions, and 80 mg / L citric acid was added to a 500 mL beaker placed in a jar tester. Next, the pH of the wastewater composition was adjusted to 9 with a 10% aqueous sodium hydroxide solution while stirring at 150 rpm.

[0169] 90 mg of the wastewater treatment agent G was added (so that the input amount was 300 mg / L (wastewater composition)) and stirred at 150 rpm for 5 minutes. Then, 0.6 mg of OA-23 was added as a polymer flocculant (so that the input amount was 2 mg / L (wastewater composition)) and stirred at 50 rpm for 5 minutes. After stopping the stirring and leaving it to stand for 5 minutes, the resulting slurry was separated into a solid component and a supernatant component, thereby carrying out the wastewater treatment method of the present invention. The concentrations of zinc and nickel remaining in the supernatant component were measured. The results are shown in Table 6.

[0170] Example 25 The same procedure as in Example 24 was carried out, except that HIDS4Na was changed to HEDTA, to obtain 100 g of wastewater treatment agent H. The composition of wastewater treatment agent H is shown in Table 4. The evaluation results of the wastewater treatment agent are shown in Table 6.

[0171] Example 31 In a 200mL beaker, 8.0g of 15% by mass PDAA-9 aqueous solution, 0.04g of 50% by mass HEDTA aqueous solution, and 82.5g of water were added, stirred, and then 5.0g of 20% by mass NaSH aqueous solution was added. Next, 4.4g of 45% by mass sodium hydrogen sulfide aqueous solution was added, and stirred for 30 minutes to obtain 100g of wastewater treatment agent N, which corresponds to the wastewater treatment agent of the present invention. The composition of the wastewater treatment agent N is shown in Table 4.

[0172] 300 mL of an aqueous solution (wastewater composition) containing 50 mg / L zinc ions, 50 mg / L nickel ions, and 80 mg / L citric acid was added to a 500 mL beaker placed in a jar tester. Next, the pH of the wastewater composition was adjusted to 9 with a 10% aqueous sodium hydroxide solution while stirring at 150 rpm.

[0173] 900 mg of the wastewater treatment agent N was added (so that the input amount was 3,000 mg / L (wastewater composition)) and stirred at 150 rpm for 5 minutes. Next, 0.6 mg of OA-23 was added as a polymer flocculant (so that the input amount was 2 mg / L (wastewater composition)) and stirred at 50 rpm for 5 minutes. After stopping the stirring and leaving it to stand for 5 minutes, the resulting slurry was separated into a solid component and a supernatant component, thereby carrying out the wastewater treatment method of the present invention. The concentrations of zinc and nickel remaining in the supernatant component were measured. The results are shown in Table 6.

[0174] Example 32 In a 300mL beaker, 140g of 15% by mass PDAA-10 aqueous solution and 0.7g of 50% by mass HIDS4Na aqueous solution were added, stirred, and then 5.0g of 20% by mass sodium hydroxide aqueous solution was added. Next, 77.8g of 45% by mass NaSH aqueous solution was added, stirred for 30 minutes, and then 123.5g of water was distilled off to obtain 100g of wastewater treatment agent O, which corresponds to the wastewater treatment agent of the present invention. The composition of the wastewater treatment agent O is shown in Table 4.

[0175] 300 mL of an aqueous solution (wastewater composition) containing 50 mg / L zinc ions, 50 mg / L nickel ions, and 80 mg / L citric acid was added to a 500 mL beaker placed in a jar tester. Next, the pH of the wastewater composition was adjusted to 9 with a 10% aqueous sodium hydroxide solution while stirring at 150 rpm.

[0176] The wastewater treatment agent O was added in an amount of 51.3 mg (to give a dosage of 171 mg / L (wastewater composition)) and stirred at 150 rpm for 5 minutes. Then, OA-23 was added as a polymer flocculant in an amount of 0.6 mg (to give a dosage of 2 mg / L (wastewater composition)) and stirred at 50 rpm for 5 minutes. After stopping the stirring and leaving it to stand for 5 minutes, the resulting slurry was separated into a solid component and a supernatant component, thereby carrying out the wastewater treatment method of the present invention. The concentrations of zinc and nickel remaining in the supernatant component were measured. The results are shown in Table 6.

[0177] Example 33 In a 200mL beaker, 40.0g of 15% by mass PDAA-2 aqueous solution, 0.2g of 50% by mass HIDS4Na aqueous solution, 32.6g of water, and 5.0g of 20% by mass sodium hydroxide aqueous solution were added. Then, 22.2g of 45% by mass K2S aqueous solution was added, and the mixture was stirred for 30 minutes to obtain 100g of wastewater treatment agent P, which corresponds to the wastewater treatment agent of the present invention. The composition of the wastewater treatment agent P is shown in Table 4.

[0178] 300 mL of an aqueous solution (wastewater composition) containing 50 mg / L zinc ions, 50 mg / L nickel ions, and 80 mg / L citric acid was added to a 500 mL beaker placed in a jar tester. Next, the pH of the wastewater composition was adjusted to 9 with a 10% aqueous sodium hydroxide solution while stirring at 150 rpm.

[0179] Next, 180 mg of the wastewater treatment agent P was added (so that the input amount was 600 mg / L (wastewater composition)) and stirred at 150 rpm for 5 minutes. Next, 0.6 mg of OA-23 (so that the input amount was 2 mg / L (wastewater composition)) was added as a polymer flocculant and stirred at 50 rpm for 5 minutes. After stopping the stirring and leaving it to stand for 5 minutes, the resulting slurry was separated into a solid component and a supernatant component, thereby carrying out the wastewater treatment method of the present invention. The concentrations of zinc and nickel remaining in the supernatant component were measured. The results are shown in Table 6.

[0180] Example 34 In a 200mL beaker, 20.0g of 15% by mass PDAA-3 aqueous solution, 0.2g of 50% by mass HEDTA aqueous solution, 52.6g of water were added, and after stirring, 5.0g of 20% by mass sodium hydroxide aqueous solution was added. Next, 22.2g of 45% by mass Ca polysulfide aqueous solution was added, and then stirred for 30 minutes to obtain 100g of wastewater treatment agent Q, which corresponds to the wastewater treatment agent of the present invention. The composition of the wastewater treatment agent Q is shown in Table 4.

[0181] 300 mL of an aqueous solution (wastewater composition) containing 50 mg / L zinc ions, 50 mg / L nickel ions, and 80 mg / L citric acid was added to a 500 mL beaker placed in a jar tester. Next, the pH of the wastewater composition was adjusted to 9 with a 10% aqueous sodium hydroxide solution while stirring at 150 rpm.

[0182] Next, 180 mg of the wastewater treatment agent Q was added (so that the input amount was 600 mg / L (wastewater composition)) and stirred at 150 rpm for 5 minutes. Next, 0.6 mg of OA-23 was added as a polymer flocculant (so that the input amount was 2 mg / L (wastewater composition)) and stirred at 50 rpm for 5 minutes. After stopping the stirring and leaving it to stand for 5 minutes, the resulting slurry was separated into a solid component and a supernatant component, thereby carrying out the wastewater treatment method of the present invention. The concentrations of zinc and nickel remaining in the supernatant component were measured. The results are shown in Table 6.

[0183] [Table 5]

[0184] [Table 6]

[0185] In Examples 18 to 34, the wastewater treatment method of the present invention was carried out by adding an aqueous solution (corresponding to the wastewater treatment agent of the present invention) in which the inorganic sulfide (A), polydiallylamine (B), and organic amine compound (C) were mixed in advance in the same amounts as in Examples 1 to 17 to the wastewater composition. The same treatment results as in Examples 1 to 17 were obtained.

[0186] Examples 35 to 41, Comparative Examples 30 to 33 The same operations as in Example 1 were carried out (the wastewater treatment method of the present invention was carried out) except that the amount of NaSH added, the type and amount of polydiallylamine (B), and the amount of HIDS4Na added in Example 1 were changed to those shown in Examples 35 to 41 and Comparative Examples 30 to 33 in Table 7. The results are shown in Table 7.

[0187] [Table 7]

[0188] Examples 35 to 41 are examples in which the ratio of the amount of the organic amine compound (C) added to the inorganic sulfide (A) was kept constant, while the ratio of the amount of the polydiallylamine (B) added to the inorganic sulfide (A) was varied within the range of the present invention, and the nickel and zinc concentrations were reduced within the range of the present invention.

[0189] Comparative Examples 30 to 33 are examples where treatment was carried out outside the range of the present invention. Under conditions outside the range of the present invention, zinc could not be treated to the effluent standard value of 2 mg / L or less, and zinc treatment was insufficient.

[0190] Examples 42 to 45, Comparative Examples 34 to 36 The same operations as in Example 1 were carried out (the wastewater treatment method of the present invention was carried out) except that the amount of NaSH added, the type and amount of polydiallylamine (B), and the type and amount of organic amine compound (C) added in Example 1 were changed to those shown in Examples 42 to 45 and Comparative Examples 34 to 36 in Table 8. The results are shown in Table 8.

[0191] [Table 8]

[0192] Examples 42 to 45 are examples in which the ratio of the amount of polydiallylamine (B) added to the inorganic sulfide (A) was kept constant, while the ratio of the amount of organic amine compound (C) added to the inorganic sulfide (A) was varied within the range of the present invention, and the nickel and zinc concentrations were reduced within the range of the present invention.

[0193] Comparative Examples 34 to 37 are examples in which treatment was carried out outside the range of the present invention. Under conditions where the ratio was outside the range of the present invention, zinc could not be treated to the effluent standard value of 2 mg / L or less, and zinc treatment was insufficient.

[0194] Example 46 300 mL of an aqueous solution (wastewater composition) containing 50 mg / L zinc ions, 50 mg / L nickel ions, and 100 mg / L tartaric acid (corresponding to the carboxylic acid compound of this wastewater) was added to a 500 mL beaker placed in a jar tester. Next, while stirring at 150 rpm, a 10% aqueous sodium hydroxide solution was added to adjust the wastewater composition to pH 9 (pH after addition of alkali). In the wastewater composition, the molar ratio of the carboxylic acid compound to the zinc ion (moles of the carboxylic acid compound ÷ moles of the zinc ion) was 0.87 (mol / mol).

[0195] Next, 18 mg of NaSH (addition amount 60 mg / L (wastewater composition)) was added as the inorganic sulfide (A), 11 mg of PDAA-1 (addition amount 36 mg / L (wastewater composition)) was added as the polydiallylamine (B), and 0.18 mg of HIDS4Na (addition amount 0.6 mg / L (wastewater composition)) was added as the organic amine compound (C) to the wastewater composition, and the mixture was stirred at 150 rpm for 5 minutes.

[0196] Next, 0.6 mg (addition amount 2 mg / L (wastewater composition)) of OA-23 was added as a polymer flocculant, and the mixture was stirred at 50 rpm for 5 minutes.

[0197] After stopping the stirring and leaving it to stand for 5 minutes, the resulting slurry was separated into a solid component and a supernatant component, and the wastewater treatment method of the present invention was carried out. The concentrations of zinc and nickel remaining in the supernatant component were measured. The results are shown in Table 9.

[0198] Example 47 The same procedure as in Example 46 was carried out and evaluation was performed, except that lactic acid (concentration 100 mg / L) was used instead of tartaric acid (concentration 100 mg / L) in Example 46. The results are shown in Table 9. The molar ratio of the carboxylic acid compound to zinc ions (moles of the carboxylic acid compound ÷ moles of zinc ions) was 1.45 (mol / mol).

[0199] Example 48 300 mL of an aqueous solution (wastewater composition) containing 20 mg / L zinc ions, 20 mg / L nickel ions, and 10 mg / L citric acid (corresponding to the carboxylic acid compound of this wastewater) was added to a 500 mL beaker placed in a jar tester. Next, while stirring at 150 rpm, a 10% aqueous calcium hydroxide solution was added to adjust the pH of the wastewater composition to 10 (pH after addition of alkali). In the wastewater composition, the molar ratio of the carboxylic acid compound to the zinc ion (moles of the carboxylic acid compound ÷ moles of the zinc ion) was 0.17 (mol / mol).

[0200] Next, 18 mg of NaSH (addition amount 60 mg / L (wastewater composition)) was added as the inorganic sulfide (A) to the wastewater composition, 11 mg of PDAA-3 (addition amount 36 mg / L (wastewater composition)) was added as the polydiallylamine (B), and 0.18 mg of DPTA (addition amount 0.6 mg / L (wastewater composition)) was added as the organic amine compound (C), and the mixture was stirred at 150 rpm for 5 minutes.

[0201] Next, 0.6 mg (addition amount 2 mg / L (wastewater composition)) of OA-23 was added as a polymer flocculant, and the mixture was stirred at 50 rpm for 5 minutes.

[0202] After stopping the stirring and leaving it to stand for 5 minutes, the resulting slurry was separated into a solid component and a supernatant component, and the wastewater treatment method of the present invention was carried out. The concentrations of zinc and nickel remaining in the supernatant component were measured. The results are shown in Table 9.

[0203] Example 49 The same procedure as in Example 48 was carried out and evaluation was performed, except that the pH after the addition of the 10% calcium hydroxide aqueous solution in Example 48 was changed from pH 10 to pH 11. The results are shown in Table 9.

[0204] Example 50 300 mL of an aqueous solution (wastewater composition) containing 500 mg / L zinc ions, 500 mg / L nickel ions, and 200 mg / L lactic acid (corresponding to the carboxylic acid compound of this wastewater) was added to a 500 mL beaker placed in a jar tester. Next, while stirring at 150 rpm, a 10% aqueous sodium hydroxide solution was added to adjust the pH of the wastewater composition to 10. In the wastewater composition, the molar ratio of the carboxylic acid compound to the zinc ion (moles of the carboxylic acid compound ÷ moles of the zinc ion) was 0.29 (mol / mol).

[0205] Next, 18 mg of NaSH (addition amount 60 mg / L (wastewater composition)) was added as the inorganic sulfide (A), 11 mg of PDAA-5 (addition amount 36 mg / L (wastewater composition)) was added as the polydiallylamine (B), and 0.18 mg of HEDTA (addition amount 0.6 mg / L (wastewater composition)) was added as the organic amine compound (C) to the wastewater composition, and the mixture was stirred at 150 rpm for 5 minutes.

[0206] Next, 0.6 mg (addition amount 2 mg / L (wastewater composition)) of OA-23 was added as a polymer flocculant, and the mixture was stirred at 50 rpm for 5 minutes.

[0207] After stopping the stirring and leaving it to stand for 5 minutes, the resulting slurry was separated into a solid component and a supernatant component, and the wastewater treatment method of the present invention was carried out. The concentrations of zinc and nickel remaining in the supernatant component were measured. The results are shown in Table 9.

[0208] Example 51 The same procedure as in Example 50 was carried out and evaluation was performed, except that the pH after the addition of the 10% sodium hydroxide aqueous solution in Example 50 was changed from pH 10 to pH 11. The results are shown in Table 9.

[0209] Example 52 300 mL of an aqueous solution (wastewater composition) containing 500 mg / L zinc ions, 500 mg / L nickel ions, and 20 mg / L ethylenediaminetetraacetic acid (corresponding to the carboxylic acid compound of this wastewater) was added to a 500 mL beaker placed in a jar tester. Next, while stirring at 150 rpm, a 10% aqueous calcium hydroxide solution was added to adjust the pH of the wastewater composition to 10. In the wastewater composition, the molar ratio of the carboxylic acid compound to the zinc ion (moles of the carboxylic acid compound ÷ moles of the zinc ion) was 0.29 (mol / mol).

[0210] Next, 18 mg of NaSH (addition amount 60 mg / L (wastewater composition)) was added as the inorganic sulfide (A), 11 mg of PDAA-5 (addition amount 36 mg / L (wastewater composition)) was added as the polydiallylamine (B), and 0.18 mg of HIDS4Na (addition amount 0.6 mg / L (wastewater composition)) was added as the organic amine compound (C) to the wastewater composition, and the mixture was stirred at 150 rpm for 5 minutes.

[0211] Next, 0.6 mg (addition amount 2 mg / L (wastewater composition)) of OA-23 was added as a polymer flocculant, and the mixture was stirred at 50 rpm for 5 minutes.

[0212] After stopping the stirring and leaving it to stand for 5 minutes, the resulting slurry was separated into a solid component and a supernatant component, and the wastewater treatment method of the present invention was carried out. The concentrations of zinc and nickel remaining in the supernatant component were measured. The results are shown in Table 9.

[0213] Example 53 The same procedure as in Example 52 was carried out and evaluation was performed, except that the pH after the addition of the 10% calcium hydroxide aqueous solution in Example 52 was changed from pH 10 to pH 11. The results are shown in Table 9.

[0214] [Table 9]

[0215] Examples 46 and 47 are examples in which wastewater containing zinc and nickel contained various carboxylic acids, and the nickel and zinc concentrations were reduced regardless of the type of carboxylic acid.

[0216] Examples 48 to 53 are examples in which wastewater containing zinc and nickel was treated using various carboxylic acids at a pH of 10 or 11 after addition of alkali, and the zinc concentration was reduced regardless of the pH. Example 54 300 mL of an aqueous solution (wastewater composition) containing 50 mg / L zinc ions, 50 mg / L nickel ions, and 80 mg / L citric acid was added to a 500 mL beaker placed in a jar tester. Next, while stirring at 150 rpm, a 10% aqueous sodium hydroxide solution was added to adjust the pH of the wastewater composition to 9. In the wastewater composition, the molar ratio of the carboxylic acid compound to the zinc ions (moles of the carboxylic acid compound ÷ moles of the zinc ions) was 0.54 (mol / mol).

[0217] Next, 18 mg of sodium hydrogen sulfide was added to the wastewater composition (so that the amount was 60 mg / L (wastewater composition)), and 11 mg of PDAA-1 was added (so that the amount was 36 mg / L (wastewater composition)), 0.18 mg of HIDS4Na was added (so that the amount was 0.6 mg / L (wastewater composition)), and 4.5 mg of PIP-DTC as a solid content (so that the amount was 15 mg / L (wastewater composition)) (11.25 mg of an aqueous solution containing 40% by mass of PIP-DTC (so that the amount was 37.5 mg / L (wastewater composition))) was added, and the mixture was stirred at 150 rpm for 5 minutes. Next, 0.6 mg of OA-23 was added as a polymer flocculant (so that the amount was 2 mg / L (wastewater composition)), and the mixture was stirred at 50 rpm for 5 minutes. After stopping the stirring and leaving it for 5 minutes, the supernatant was separated, and the zinc and nickel concentrations remaining in the wastewater composition were measured. The results are shown in Table 10. Examples 55 to 59 In Example 54, the type and amount of inorganic sulfide (A), the type and amount of polydiallylamine (B), the type and amount of organic amine compound (C) having at least three carboxy groups and one hydroxy group, and the type and amount of compound (D) having a dithiocarbamic acid group were changed to those shown in Examples 55 to 59 in Table 10, but the same operation as in Example 54 was performed (the wastewater treatment method of the present invention was performed). The results are shown in Table 10.

[0218] [Table 10]

[0219] Examples 54 to 59 are examples in which a compound (D) having a dithiocarbamic acid group was further used for treatment, and the zinc and nickel concentrations could be further reduced.

[0220] Example 60 In a 200 mL beaker, 40.0 g of 15% by mass PDAA-1 aqueous solution, 0.2 g of 50% by mass HIDS4Na aqueous solution, 6.3 g of an aqueous solution containing 40% by mass PIP-DTC, and 26.3 g of water were added, stirred, and then 5.0 g of 20% by mass sodium hydroxide aqueous solution was added. Next, 22.2 g of 45% by mass NaSH aqueous solution was added, and stirred for 30 minutes to obtain 100 g of wastewater treatment agent R, which corresponds to the wastewater treatment agent of the present invention.

[0221] The composition of the wastewater treatment agent R is sodium hydrogen sulfide (corresponding to inorganic sulfide (A)) / PDAA-1 (corresponding to polydiallylamine (B)) / HIDS4Na (corresponding to organic amine compound (C)) / PIP-DTC (corresponding to compound having dithiocarbamic acid group (D)) / sodium hydroxide / water = 10 / 6 / 0.1 / 2.5 / 1 / 83 (all by mass %). The composition of the wastewater treatment agent R is shown in Table 11.

[0222] 300 mL of an aqueous solution (wastewater composition) containing 50 mg / L zinc ions, 50 mg / L nickel ions, and 80 mg / L citric acid was added to a 500 mL beaker placed in a jar tester. Next, the pH of the wastewater composition was adjusted to 9 with a 10% aqueous sodium hydroxide solution while stirring at 150 rpm.

[0223] 180 mg of the wastewater treatment agent R (addition amount 600 mg / L (wastewater composition)) was added and stirred at 150 rpm for 5 minutes. Next, 0.6 mg of OA-23 (addition amount 2 mg / L (wastewater composition)) was added as a polymer flocculant and stirred at 50 rpm for 5 minutes. After stopping the stirring and leaving it to stand for 5 minutes, the resulting slurry was separated into a solid component and a supernatant component, thereby carrying out the wastewater treatment method of the present invention. The concentrations of zinc and nickel remaining in the supernatant component were measured. The evaluation results of the wastewater treatment agent are shown in Table 12. Examples 61 to 65 In Example 60, the type and amount of inorganic sulfide (A), the type and amount of polydiallylamine (B), the type and amount of organic amine compound (C) having at least three carboxy groups and one hydroxy group, and the type and amount of compound (D) having a dithiocarbamic acid group were changed to those shown in Examples 61 to 65 in Table 11, but the same operation as in Example 60 was performed to obtain 100 g of wastewater treatment agents S to W. The compositions of the wastewater treatment agents S to W are shown in Table 11. The evaluation results of the wastewater treatment agents are shown in Table 12.

[0224] [Table 11]

[0225] [Table 12]

[0226] In Examples 60 to 65, the wastewater treatment method of the present invention was carried out by adding an aqueous solution (corresponding to the wastewater treatment agent of the present invention) in which the inorganic sulfide (A), the polydiallylamine (B), the organic amine compound (C), and the compound having a dithiocarbamic acid group (D) were mixed in advance in the same amounts as in Examples 54 to 59 to the wastewater composition. The same treatment results as in Examples 54 to 59 were obtained.

[0227] Examples 66 to 68 In Example 54, the type and amount of inorganic sulfide (A), the type and amount of polydiallylamine (B), the type and amount of organic amine compound (C) having at least three carboxy groups and one hydroxy group, and the type and amount of compound (D) having a dithiocarbamic acid group were changed to those shown in Examples 66 to 68 in Table 13, but the same operation as in Example 54 was performed (the wastewater treatment method of the present invention was performed). The results are shown in Table 13.

[0228] [Table 13] [Industrial Applicability]

[0229] The wastewater treatment agent and wastewater treatment method of the present invention can be used as a method for treating wastewater containing zinc and nickel discharged from plating factories and the like.

Claims

1. A wastewater treatment agent comprising: an inorganic sulfide (A); a polydiallylamine (B) having at least two repeating units represented by the following general formula (1) and / or (2); and an organic amine compound (C) having at least three carboxy groups and one hydroxy group, the wastewater treatment agent comprising 0.1 to 300 parts by mass of (B) and 0.2 to 2.5 parts by mass of (C) per 100 parts by mass of (A): 【Chemistry 1】 (In the formula, R １ , R ２ , and R ３ Each of X independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. － represents a fluoride ion, a chloride ion, a bromide ion, an iodide ion, or an ethyl sulfate anion.

2. The wastewater treatment agent according to claim 1, further comprising a compound (D) having a dithiocarbamic acid group, and the content of the compound (D) is 1 to 200 parts by mass per 100 parts by mass of the compound (A).

3. The wastewater treatment agent according to claim 1, wherein the inorganic sulfide (A) is sodium hydrogen sulfide, sodium sulfide, potassium sulfide, or calcium polysulfide.

4. The wastewater treatment agent according to claim 1, wherein the average molecular weight of the polydiallylamine (B) is 1,000 to 500,000.

5. R １ , R ２ , and R ３ The wastewater treatment agent according to claim 1 , wherein each of the is independently a hydrogen atom, a methyl group, or an ethyl group.

6. R １ , and R ２ are both methyl groups or both ethyl groups, R ３ The wastewater treatment agent according to claim 1 , wherein is a hydrogen atom.

7. X － The wastewater treatment agent according to claim 1, wherein is a chloride ion.

8. 2. The wastewater treatment agent according to claim 1, wherein the organic amine compound (C) having at least three carboxy groups and one hydroxy group is hydroxyiminodisuccinic acid, hydroxyethylethylenediaminetriacetic acid, or diaminohydroxypropanetetraacetic acid.

9. The wastewater treatment agent according to claim 1, further comprising water, the content of the water being 100 to 5000 parts by mass per 100 parts by mass of the (A).

10. A wastewater treatment method, comprising adding the wastewater treatment agent according to any one of claims 1 to 9 to wastewater containing a carboxylic acid compound, zinc, and nickel, stirring the mixture, then adding a polymer flocculant and stirring the mixture to form a slurry, and then separating a solid component from the slurry.

11. The wastewater treatment method according to claim 10, wherein the carboxylic acid compound is citric acid, tartaric acid, lactic acid, or ethylenediaminetetraacetic acid.

12. A wastewater treatment method comprising adding an inorganic sulfide (A), a polydiallylamine (B) having at least two or more repeating units represented by the following general formula (1) and / or (2), and an organic amine compound (C) having at least three carboxy groups and one hydroxy group to wastewater containing a carboxylic acid compound, zinc, and nickel, stirring the mixture, then adding a polymer flocculant and stirring to form a slurry, and then separating a solid component from the slurry, wherein the amount of (B) added is 0.1 to 300 parts by mass per 100 parts by mass of (A), and the amount of (C) added is 0.2 to 2.5 parts by mass per 100 parts by mass of (A). 【Chemistry 2】 (In the formula, R １ , R ２ , and R ３ Each of X independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. － represents a fluoride ion, a chloride ion, a bromide ion, an iodide ion, or an ethyl sulfate anion.

13. The wastewater treatment method according to claim 12, further comprising the step of adding a compound (D) having a dithiocarbamic acid group in addition to the components (A), (B), and (C).

14. The wastewater treatment method according to claim 12 or 13, wherein the amount of the inorganic sulfide (A) added is 0.1 to 20 mol per 1 mol of zinc in the wastewater.

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