JP7311951B2 - Water treatment method and water treatment equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a water treatment method and a water treatment apparatus for treating organic matter-containing water containing organic matter.

Chemical factories, paper and pulp factories, printing factories, machine manufacturing factories, food factories, pharmaceutical factories, and the like discharge wastewater of various properties. These wastewaters contain, for example, organic matter indexed by chemical oxygen demand (COD), and if organic matter is discharged into sea areas, lakes, etc. as it is, it may cause environmental pollution. For this reason, the Water Pollution Control Law stipulates uniform wastewater standards for the COD concentration of wastewater discharged into sea areas, lakes, and marshes from business establishments with specified facilities. It has been demanded.

In addition, in areas where uniform wastewater standards alone are not sufficient to prevent water pollution, prefectures have established additional wastewater standards through ordinances. Wastewater standards for added COD vary depending on the type of industry and region, but there are some examples that set a strict standard of 20 mg/L or less.

In order to reduce organic substances in wastewater, for example, Patent Document 1 proposes a method of aerobic microbial treatment of wastewater concentrated by reverse osmosis. However, although this method describes the aerobic microbial treatment of concentrated wastewater, the subsequent treatment is not explicitly described.

In Patent Document 2, the water to be treated is separated into permeated water and concentrated water by membrane separation treatment using a nanofiltration membrane and / or reverse osmosis membrane, the concentrated water is biologically treated, and after the biological treatment, gravity sedimentation is performed. , a sand filtration method, a membrane filtration method, and the like have been proposed. However, Patent Document 2 does not show any specific examples, nor does it clearly describe the treatment after the solid-liquid separation treatment.

Although it is possible to reduce the amount of organic matter in wastewater to some extent by the conventional techniques described in Patent Documents 1 and 2, etc., the performance of treating the organic matter is not sufficient.

JP-A-51-148968 JP 2009-072766 A

An object of the present invention is to provide a water treatment method and a water treatment apparatus capable of efficiently reducing organic matter in organic matter-containing water.

The present invention includes a concentration step of concentrating organic matter-containing water containing organic matter by a membrane separation treatment using a microfiltration membrane or an ultrafiltration membrane, and a biological treatment step of biologically treating the concentrated water obtained in the concentration step. , adding an inorganic coagulant, an organic coagulant (excluding dimethylamine/epichlorohydrin/ammonia condensate) and a polymer flocculant to the biologically treated water treated in the biological treatment step, and coagulating and sedimenting and a coagulation sedimentation step of obtaining treated water by treatment, wherein the concentration CODMn is 1000 mg/L or more, and the cation colloid equivalent value at pH 6 of the organic coagulant is 6.0 meq/g or more. There is a water treatment method.

In the water treatment method , the organic coagulant is preferably a polyamine polymer.

In the water treatment method, the polyamine-based polymer is a dimethylamine /epichlorohydrin/ethylenediamine condensate, polyethyleneimine, a diallyldimethylammonium halide polymer or a crosslinked polymer thereof, or a mixture of diallyldimethylammonium halide and diallylamine. At least one of a copolymer or a crosslinked product of the copolymer, and polyamidine is preferable.

Further, the present invention provides a concentrating means for concentrating organic matter-containing water containing organic matter by a membrane separation treatment using a microfiltration membrane or an ultrafiltration membrane, and a biological treatment for biologically treating the concentrated water obtained by the concentrating means. adding an inorganic coagulant, an organic coagulant (excluding dimethylamine/epichlorohydrin/ammonia condensate) and a polymer flocculant to the biologically treated water treated by the biological treatment means, coagulating sedimentation means for obtaining treated water by coagulating sedimentation treatment, wherein the concentration CODMn is 1000 mg/L or more, and the cation colloid equivalent value of the organic coagulant at pH 6 is 6.0 meq/ g or more, water treatment equipment.

In the water treatment device , the organic coagulant is preferably a polyamine polymer.

In the water treatment device, the polyamine-based polymer is a dimethylamine /epichlorohydrin/ethylenediamine condensate, polyethyleneimine, a diallyldimethylammonium halide polymer or a crosslinked polymer thereof, or a mixture of diallyldimethylammonium halide and diallylamine. At least one of a copolymer or a crosslinked product of the copolymer, and polyamidine is preferable.

INDUSTRIAL APPLICABILITY The present invention can provide a water treatment method and a water treatment apparatus capable of efficiently reducing organic matter in organic matter-containing water.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram which shows an example of the water treatment apparatus which concerns on embodiment of this invention.

An embodiment of the present invention will be described below. This embodiment is an example of implementing the present invention, and the present invention is not limited to this embodiment.

An outline of an example of a water treatment apparatus according to an embodiment of the present invention is shown in FIG. 1, and its configuration will be described. The water treatment apparatus 1 shown in FIG. 1 has a concentration apparatus 10 as concentration means, a biological treatment apparatus 12 as biological treatment means, and a first reaction tank 14, a second reaction tank 16 and a sedimentation tank 18 as coagulation sedimentation means. and a precipitation device. The water treatment apparatus 1 may include a water tank (not shown) for storing the water to be treated in the upstream stage of the concentrator 10 .

In the water treatment apparatus 1 shown in FIG. 1, the water to be treated pipe 20 is connected to the inlet of the concentrator 10 . The outlet of the concentrator 10 and the inlet of the biological treatment device 12 are connected by a concentrated water pipe 22 . The outlet of the biological treatment device 12 and the inlet of the first reaction tank 14 are connected by a biologically treated water pipe 24 . The outlet of the first reaction tank 14 and the inlet of the second reaction tank 16 are connected by a first reaction water pipe 26 . The outlet of the second reaction tank 16 and the inlet of the sedimentation tank 18 are connected by a second reaction water pipe 28 . A treated water pipe 30 is connected to the treated water outlet of the sedimentation tank 18, and a sludge discharge pipe 32 is connected to the lower sludge outlet. An inorganic coagulant addition pipe 34, an organic coagulant addition pipe 36, and a pH adjuster addition pipe 38 are connected to the first reaction tank 14, and a stirring device 42 having stirring blades or the like may be installed. A polymer flocculant addition pipe 40 may be connected to the second reaction tank 16, and a stirring device 44 having stirring blades or the like may be installed.

An example of the water treatment method and the operation of the water treatment apparatus 1 according to this embodiment will be described.

The organic matter-containing water, which is the water to be treated, is stored in the water tank to be treated as necessary, and then supplied to the concentrator 10 through the water to be treated pipe 20 . Organic matter-containing water is concentrated in the concentration device 10 (concentration step). The concentrated water obtained in the concentration step is supplied to the biological treatment device 12 through the concentrated water pipe 22 . In the biological treatment device 12, the concentrated water is biologically treated (biological treatment process).

Next, a coagulant is added to the biologically treated water treated in the biological treatment process, and treated water is obtained by coagulation-sedimentation treatment (coagulation-sedimentation process). Specifically, for example, the coagulating sedimentation step is as follows.

The biologically treated water treated in the biological treatment process is supplied from the biological treatment device 12 to the first reaction tank 14 through the biologically treated water pipe 24 . In the first reaction tank 14, an inorganic coagulant is added through an inorganic coagulant addition pipe 34 (inorganic coagulant addition step), and an organic coagulant is added through an organic coagulant addition pipe 36 (organic coagulant addition step). The biologically treated water, the inorganic coagulant and the organic coagulant in the first reaction tank 14 are stirred by the stirring device 42 to insolubilize the organic matter (insolubilization step). If necessary, a pH adjuster may be added to the first reaction tank 14 through the pH adjuster addition pipe 38 to adjust the pH (pH adjustment step). The inorganic flocculant adjusted to a predetermined pH becomes, for example, a metal hydroxide, and fine flocs are formed together with the insolubilized organic matter (floc forming step).

The first reaction water containing fine flocs (fine floc-containing water) is supplied from the first reaction tank 14 to the second reaction tank 16 through the first reaction water pipe 26 . In the second reaction tank 16, a polymer flocculant is added through a polymer flocculant addition pipe 40 (polymer flocculant addition step). The water containing fine flocs and the polymer coagulant in the second reaction tank 16 are stirred by the stirring device 44 . The polymer flocculant causes the fine flocs to associate with each other to grow the flocs (floc growth step).

The second reaction water containing flocs (floc-containing water) is supplied from the second reaction tank 16 to the sedimentation tank 18 through the second reaction water pipe 28 . In the sedimentation tank 18, solid-liquid separation into treated water and flocs is performed by natural sedimentation or the like (solid-liquid separation step). The treated water in which the organic matter has been reduced is discharged through the treated water pipe 30, and the floc is discharged as sludge through the sludge discharge pipe 32.

The present inventors have obtained concentrated water by concentrating organic matter-containing water, subjecting the concentrated water to biological treatment, and then treating the concentrated water by coagulation sedimentation treatment to remove organic matter such as COD components, pigments, turbidity, etc. It was found that in organic matter-containing water containing, it shows good flocculation treatment performance and can efficiently reduce organic matter and the like.

By performing the biological treatment after the concentration treatment, the decomposition products are different from when the biological treatment is performed without the concentration treatment. Cheap. This is because biologically treated water, which has been subjected to biological treatment after concentration treatment, contains more negatively charged chemical substances, so inorganic coagulants, organic coagulants, polymer coagulants, etc. It is presumed that the charge is neutralized by the aggregating agent to form a shape that facilitates agglomeration.

Various methods may be used for concentration in the concentration step, and for example, evaporation treatment, membrane filtration treatment, or the like may be used for concentration.

Evaporation treatment includes methods such as natural evaporation, heat evaporation, spray evaporation, and vacuum evaporation.

The membrane used for membrane filtration is not particularly limited, but may be a microfiltration membrane (MF membrane), an ultrafiltration membrane (UF membrane), a nanofiltration membrane (NF membrane), a reverse osmosis membrane (RO membrane), or the like. mentioned. A microfiltration membrane (MF membrane), an ultrafiltration membrane (UF membrane), and a nanofiltration membrane (NF membrane) are preferable from the viewpoint that concentration can be effectively performed. An extrafiltration membrane (UF membrane) is more preferred, and an ultrafiltration membrane (UF membrane) is even more preferred. If it is a reverse osmosis membrane (RO membrane) with a small separation particle size, the membrane is easily clogged, and if it is a microfiltration membrane (MF membrane), the separation particle size is large and it is more difficult to concentrate than other membranes. may not be effectively reduced.

The microfiltration membrane has a pore size of 0.1 μm or more and 10 μm or less, and the ultrafiltration membrane has a nominal pore size of 0.001 μm or more and less than 0.1 μm. In terms of molecular weight cutoff, the molecular weight cutoff of the ultrafiltration membrane is 1,000 or more and less than 1,000,000.

The material of the filtration membrane is not particularly limited. membranes and the like.

The shape of the filtration membrane is not particularly limited, but may be, for example, hollow fiber membranes, tubular membranes, flat membranes, spiral membranes, or the like. There are no particular restrictions on the water flow system of the filtration membrane, but any water flow system such as an internal pressure system or an external pressure system can be applied, and any filtration method such as cross-flow filtration or dead-end filtration can be applied.

In the biological treatment process, aerobic biological treatment or anaerobic biological treatment is performed. For example, it is a process of biologically oxidizing or reducing organic matter in concentrated water by microorganisms such as aerobic microorganisms and anaerobic microorganisms, such as standard activated sludge method, biofilm method, membrane separation activated sludge method (MBR) , a fixed bed method, a fluidized bed method, and the like.

At least one of an inorganic coagulant, an organic coagulant, and a polymer coagulant is used as the coagulant used in the coagulation-sedimentation step. Although a combination of an inorganic coagulant, an organic coagulant, and a polymer coagulant is used in the water treatment device 1 shown in FIG. 1, it is not limited to this. In the coagulation-sedimentation process, a combination of an inorganic coagulant and an organic coagulant, a combination of an inorganic coagulant and a polymer coagulant, or a combination of an inorganic coagulant and an organic coagulant is used because the effect of reducing organic matter is high. A flocculant is preferably used in combination with a polymer flocculant, and more preferably a flocculant is used in combination with an inorganic flocculant, an organic flocculant and a polymer flocculant.

Examples of inorganic flocculants used in the coagulation-sedimentation step include iron-based inorganic flocculants such as ferric chloride and polyferric sulfate, aluminum-based inorganic flocculants such as aluminum sulfate and polyaluminum chloride (PAC), and the like. mentioned.

The amount of the inorganic flocculant added is not particularly limited. Depending on the concentration of suspended solids, organic matter, etc. in the biologically treated water to be treated, it is preferably in the range of, for example, 10 to 50,000 mg/L.

Examples of pH adjusters include acids such as hydrochloric acid and sulfuric acid, and alkalis such as sodium hydroxide.

The pH in the coagulation-sedimentation step may be adjusted, for example, within the range of 4-11.

The stirring speed after adding the inorganic coagulant may be, for example, rapid stirring at 100 to 300 rpm.

Examples of the organic coagulant used in the coagulation-sedimentation step include polyamine-based polymers, polyacrylic acid-based polymers, etc. Polyamine-based polymers are preferred because they are highly effective in reducing organic matter and the like.

A polyamine-based polymer is a polymer formed from a monomer having at least one of primary amine, secondary amine, tertiary amine and quaternary ammonium. Chlorohydrin/ammonia condensate, dimethylamine/epichlorohydrin/ethylenediamine condensate, polyethyleneimine, diallyldimethylammonium halide polymer or crosslinked polymer thereof, copolymer of diallyldimethylammonium halide and diallylamine or its Crosslinked copolymers, polyamidines, and the like can be mentioned.

A polyacrylic acid-based polymer is a polymer formed from at least one of acrylic acid and acrylic acid ester, and includes polyacrylic acid, polyacrylic acid ester, and the like.

The weight average molecular weight of the polyamine-based polymer and polyacrylic acid-based polymer is, for example, in the range of 10,000 to 50,000,000, preferably in the range of 20,000 to 9,000,000.

The dimethylamine/epichlorohydrin/ammonia condensate has the following formula (1)
and a structure represented by the following formula (2)
is a polymer containing a structure represented by In the polymer, the ratio of the structure represented by formula (2) to the structure represented by formula (1) is the molar ratio (structure represented by formula (2): structure represented by formula (1)). and, for example, 0.01:9.99 to 7:3.

The viscosity of a 50% by weight aqueous solution of dimethylamine/epichlorohydrin/ammonia condensate is, for example, 500 mPa s or more, preferably 800 mPa s or more, and more preferably 1,000 mPa s or more. preferable. Although the upper limit of the viscosity of the 50% by weight aqueous solution is not particularly limited, it is preferably 4,000 mPa·s or less, more preferably 2,000 mPa·s or less. The cationic colloid equivalent value of the dimethylamine/epichlorohydrin/ammonia condensate is, for example, 6.0 meq/g or more (pH 6), preferably 6.5 meq/g or more (pH 6).

The dimethylamine/epichlorohydrin/ethylenediamine condensate has the structure represented by the above formula (1) and the following formula (3)
is a polymer containing a structure represented by In the polymer, the ratio of the structure represented by formula (3) to the structure represented by formula (1) is the molar ratio (structure represented by formula (3): structure represented by formula (1)). and, for example, 0.01:9.99 to 7:3.

The viscosity of a 50% by weight aqueous solution of the dimethylamine/epichlorohydrin/ethylenediamine condensate is, for example, 500 mPa·s or more, preferably 800 mPa·s or more. Although the upper limit of the viscosity of the 50% by weight aqueous solution is not particularly limited, it is preferably 4,000 mPa·s or less, more preferably 2,000 mPa·s or less. The cationic colloid equivalent value of the dimethylamine/epichlorohydrin/ethylenediamine condensate is, for example, 6.0 meq/g or more (pH 6), preferably 6.5 meq/g or more (pH 6).

で表される構造を含むポリマである。 Polyethyleneimine is represented by the following formula (4)

is a polymer containing a structure represented by

The viscosity of a 40% by weight aqueous solution of polyethyleneimine is, for example, 1,500 mPa·s or more, preferably 2,000 mPa·s or more. Although the upper limit of the viscosity of the 40% by weight aqueous solution is not particularly limited, it is preferably 4,000 mPa·s or less. The cationic colloid equivalent value of polyethyleneimine is, for example, 6.0 meq/g or more (pH 6), preferably 6.5 meq/g or more (pH 6).

（式中、Ｘは、アニオンであり、例えば、塩化物イオン、臭化物イオン、ヨウ化物イオン等が挙げられ、塩化物イオンが好ましい。）
で表されるポリマである。 The diallyldimethylammonium halide polymer has the following formula (5)

(In the formula, X is an anion such as chloride ion, bromide ion, iodide ion, etc., and chloride ion is preferred.)
is a polymer represented by

The viscosity of a 40% by weight aqueous solution of the diallyldimethylammonium halide polymer is, for example, 5,000 mPa·s or more, preferably 8,000 mPa·s or more. Although the upper limit of the viscosity of the 40% by weight aqueous solution is not particularly limited, it is preferably 15,000 mPa·s or less. The cationic colloid equivalent value of the diallyldimethylammonium halide polymer is, for example, 6.0 meq/g or more (pH 6), preferably 6.2 meq/g or more (pH 6).

（式中、Ｒ^１，Ｒ^２は、独立して炭素数１～１０のアルキル基であり、Ｒ^３は、－Ｒ^４ＣＨ（ＯＨ）Ｒ^５Ｙ、または－Ｒ^６ＣＨ（Ｒ^７）Ｃ（Ｏ）ＮＨＣＨ_２ＮＨＣ（Ｏ）ＣＨ（Ｒ^８）Ｒ^９であり、Ｙは、Ｃｌ、Ｂｒ、Ｉ、ＯＨ、ＯＲ^１０、ＮＨ_３、Ｐ（ＣＨ_３）_３、ＳＣＨ_３、またはＣＮであり、Ｒ^４，Ｒ^５，Ｒ^６は、独立して炭素数１～１０のアルキレン基であり、Ｒ^７，Ｒ^８，Ｒ^９，Ｒ^１０は、独立して炭素数１～１０のアルキル基であり、ｎ，ｍは、モル比であり、Ｘは、アニオンであり、Ｍは、酸である。） A copolymer of diallyldimethylammonium halide and diallylamine is a polymer represented by the following structural formula (6).

(Wherein, R ¹ and R ² are independently alkyl groups having 1 to 10 carbon atoms, and R ³ is —R ⁴ CH(OH)R ⁵ Y or —R ⁶ CH(R ⁷ )C (O) _NHCH2NHC (O)CH( ^R8 ) ^R9 and Y is Cl, Br, I, OH, ^OR10 , _NH3 , P( _CH3 ) ₃ , _SCH3 , or CN , R ⁴ , R ⁵ and R ⁶ are independently alkylene groups having 1 to 10 carbon atoms, and R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are independently alkyl groups having 1 to 10 carbon atoms. where n, m are molar ratios, X is an anion, and M is an acid.)

Examples of R ¹ and R ² include methyl group, ethyl group, n-propyl, isopropyl group, n-butyl group, sec-butyl group, t-butyl group and the like, preferably methyl group. R ³ includes -CH ₂ CH(OH)CH ₂ Cl, -CH ₂ CH(CH ₃ )C(=O)NHCH ₂ NHC(=O)CH(CH ₃ )CH ₃ and the like, and -CH ₂ CH(OH)CH ₂ Cl is preferred. n and m are molar ratios, preferably m:n=0.01:9.99 to 9:1. X is an anion such as chloride ion, bromide ion, iodide ion and the like, preferably chloride ion. M _is an acid such as HCl, _H2SO4 , _HNO3 , _{H3PO4 ,} etc., with HCl being preferred.

The weight average molecular weight of the copolymer of diallyldimethylammonium halide and diallylamine is, for example, in the range of 10,000 to 50,000,000, preferably in the range of 20,000 to 8,500,000. If the weight-average molecular weight of this copolymer is less than 10,000, it may disperse without coagulation sedimentation, and if it exceeds 50,000,000, it takes time to dissolve in water or does not dissolve Sometimes.

（式中、Ｘは、アニオンであり、例えば、塩化物イオン、臭化物イオン、ヨウ化物イオン等が挙げられ、塩化物イオンが好ましい。）
で表されるポリマである。 Polyamidine is represented by the following formula (7)

(In the formula, X is an anion such as chloride ion, bromide ion, iodide ion, etc., and chloride ion is preferred.)
is a polymer represented by

The viscosity of the 0.5% by weight polyamidine salt is, for example, 1 mPa s or more, preferably 8 mPa s or more, and the cationic colloid equivalent value is, for example, 6.0 meq/g or more (pH 6). .

Here, the viscosity of an aqueous solution of an organic coagulant or the like is an index representing the molecular weight of a compound, and the higher the value, the higher the molecular weight of the compound. The viscosity of the aqueous solution of the organic coagulant is measured by a viscometer such as a Brookfield rotational viscometer.

The cation colloid equivalent value is an index representing the strength of the positive charge in the compound, and the larger the value, the stronger the positively charged compound. Cation colloid equivalent values are determined by colloid titration. Specifically, an aqueous solution in which the drug is dispersed is titrated with a potassium polyvinyl sulfate solution. The pH of the solution during titration should be 4-10.

The diallyldimethylammonium halide polymer and the copolymer of diallyldimethylammonium halide and diallylamine may be crosslinked bodies obtained by crosslinking polyfunctional crosslinkable monomers.

For example, a crosslinked diallyldimethylammonium halide polymer can be obtained by subjecting a diallyldimethylammonium halide monomer before polymerization to crosslinking polymerization of a polyfunctional crosslinkable monomer.

For example, during addition polymerization, a copolymer of crosslinked diallyldimethylammonium halide and diallylamine is obtained by heat-polymerizing a polyfunctional crosslinkable monomer at R ³ shown in the above structural formula (6). Obtainable.

The polyfunctional crosslinkable monomer used for crosslinking is not particularly limited, and examples include α,ω-dibromoalkane, di(chloromethyl)benzene, 1,3,5-tri(chloromethyl)benzene, chloride cyanur, 1,3-dichloro-2-propanol, 1,3-dibromo-2-propanol, formaldehyde, glyoxal, alkanedials, diformylbenzene, epichlorohydrin, epibromohydrin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerin-di- or triglycidyl ether, 1,1,1-trimethylolpropane-di- or triglycidyl ether, pentaerythritol-di-, tri- or tetra- glycidyl ether, sorbitol-di-, tri- or tetraglycidyl ether, bis(glycidyl)alkylamine, bis(chloroformyloxy)alkane, bis(chloroformyloxy)cyclohexane, bis(chloroformyloxy)benzene, 2,2'-bis (4-chloroformyloxyphenyl)propane, alkanediimidic acid lower alkyl ester, diamidinoalkane, tolylene diisocyanate, divinyl sulfone, bisphenol A diglycidyl ether, bisphenol S diglycidyl ether, bisphenol F diglycidyl ether, alkane-α, ω-dicarboxylic acid, pyromellitic anhydride, benzophenone-3,3′,4,4′-tetracarboxylic dianhydride, alkane-α,ω-dicarboxylic acid chloride, benzenedicarboxylic acid chloride, benzene-1,3, 5-tricarboxylic acid chloride, benzenedisulfonic acid chloride, benzene-1,3,5-trisulfonic acid chloride, cyclohexanedicarboxylic acid chloride, biphenyl-4,4'-dicarboxylic acid chloride, 2,2-bis(4-chlorocarbonyl Phenyl)propane, diphenyl ether-4,4'-dicarboxylic acid chloride, piperazine-1,4-dicarboxylic acid chloride, ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, dimethacryl tetraethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, polyethylene glycol di(meth)acrylate, N-vinyl(meth)acrylamide, N-methylallylacrylamide, glycidyl acrylate, polyethylene glycol diglycidyl ether, acrolein , Glyoxal, Vinyltrimethoxysilane, Ethylene glycol di(meth)acrylate, Diethylene glycol di(meth)acrylate, Polyethylene glycol di(meth)acrylate, Polyethylene glycol diacrylate, Propylene glycol di(meth)acrylate, Dipropylene glycol di(meth)acrylate ) acrylate, polypropylene glycol di(meth)acrylate, N,N'-methylenebis(meth)acrylamide, glycerin tri(meth)acrylate, diallyl phthalate, diallyl maleate, diallylamine, ethylene glycol diallyl ether, triallylamine, triallyl trimelli Tate, triallyl isocyanurate, triallyl phosphate, divinylbenzene, ethylene glycol diglycidyl ether, di- or polyglycidyl ether of aliphatic polyhydric alcohol, N-methylolacrylamide, glycidyl methacrylate and the like. As the polyfunctional crosslinkable monomer, one type may be used alone, or two or more types may be used in combination. Among these, epichlorohydrin, 1,3-dichloro-2-propanol, N,N-methylenebis(meth)acrylamide, and polyethylene glycol diacrylate are preferred.

The amount of the organic coagulant added is preferably 0.1 or less as a weight ratio of the amount of the organic coagulant added to the amount of the inorganic coagulant added (amount of organic coagulant added/amount of inorganic coagulant added). , 0.002 or more and 0.07 or less. If this weight ratio exceeds 0.1, the amount of the organic coagulant added becomes excessive, and the treated water quality may deteriorate compared to the optimum conditions. may become. The amount of the organic coagulant to be added is preferably determined by a jar test or the like.

In the coagulation-sedimentation step, it is preferable to add a polymer coagulant to increase the floc diameter in order to perform a better coagulation treatment. In order to perform a good flocculation treatment, it is preferable to add the polymer flocculant after the flocculation reaction by the organic flocculating agent and the inorganic flocculating agent is almost completed. Specifically, the polymer flocculant may be added in the second reaction tank 16 after the first reaction tank 14 .

Examples of polymer flocculants include nonionic polymer flocculants, anionic polymer flocculants, cationic polymer flocculants, and the like, but are not particularly limited. Acrylate copolymer, sodium acrylamidopropanesulfonate, chitosan, dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate and polyamidine. The polymer flocculants may be used singly or in combination of two or more.

The weight average molecular weight of the polymer flocculant is, for example, in the range of 500,000 to 1,000,000,000, preferably in the range of 1,000,000 to 50,000,000.

The amount of polymer flocculant to be added is not particularly limited, but is preferably in the range of 0.1 to 100 mg/L, for example.

After adding the polymer flocculant, it is preferable to moderate the stirring speed (for example, 20 to 50 rpm) to grow the floc diameter.

The liquid temperature in the flocculation treatment (insolubilization step, floc formation step, floc growth step) is not particularly limited, and is, for example, in the range of 15 to 35°C.

Solid-liquid separation between treated water and floc after coagulation treatment is not limited to the sedimentation tank. The solid-liquid separation method is not particularly limited, and examples thereof include precipitation treatment, filtration treatment, membrane separation treatment, and the like. The sedimentation treatment is not particularly limited. For example, in addition to natural sedimentation treatment using a sedimentation tank, forced sedimentation treatment using a centrifugal separator or the like may be used. In addition, the filtration treatment is not particularly limited. , and a filter medium such as plastic. Membrane separation treatment is also not particularly limited, and for example, membrane separation can be performed using a microfiltration membrane, an ultrafiltration membrane, or the like.

The organic substance-containing water to be treated may be water of any origin as long as it contains organic substances such as chromaticity components such as pigments and COD components, and is not particularly limited. Examples include wastewater from pulp factories, printing factories, machine manufacturing factories, food factories, pharmaceutical factories, etc. Examples include sugar-containing wastewater, humic acid-containing wastewater, cloth processing wastewater, etc., discharged from the above-mentioned various factories.

The solubility CODMn of the organic matter-containing water is, for example, 8 mg/L or more, preferably 50 mg/L or more, and more preferably 100 mg/L or more. If the soluble CODMn of the organic matter-containing water is less than 8 mg/L, the effect of reducing the soluble COD components by the organic coagulant may be reduced. Here, the soluble COD of the organic matter-containing water refers to the COD of the filtrate after filtering the organic matter-containing water with filter paper (No. 5C).

The chromaticity of the organic matter-containing water is, for example, 5 degrees or more, preferably 10 degrees or more, and more preferably 100 degrees or more.

The solubility CODMn of concentrated water obtained by concentrating organic matter-containing water is, for example, 300 mg/L or more, preferably 500 mg/L or more, and more preferably 1000 mg/L or more. If the soluble CODMn of the concentrated water is less than 8 mg/L, the effect of reducing the soluble COD components by the organic coagulant may be reduced. Here, the soluble COD of the organic matter-containing water refers to the COD of the filtrate after filtering the organic matter-containing water with filter paper (No. 5C).

By the water treatment method and the water treatment apparatus according to the present embodiment, for example, the water to be treated is concentrated to reduce the soluble CODMn of the biologically treated water by 30% or more, preferably 60% or more. It is possible to reduce the chromaticity of biologically treated water by 35% or more, preferably 80% or more.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.

The CODMn was measured according to the "oxygen consumption by potassium permanganate at 100°C" of the factory wastewater test method (JIS K 0102).

The viscosities of 35% by weight aqueous solution, 40% by weight aqueous solution and 50% by weight aqueous solution of the organic coagulant were measured using a Brookfield type rotational viscometer (manufactured by Eko Seiki Co., Ltd., DV-1).

The cationic colloid equivalent value of the organic coagulant was obtained by the colloid titration method as follows. The solution pH during titration was set to 6.0.

<Colloidal titration method>
1. Analysis method of cationic colloid equivalent value (1) Evaporation residue (% by weight) of a sample is measured in advance.
(2) Take 100 mL of a sample diluted with pure water to a solid content of 20 mg/L in a beaker.
(3) Adjust pH to 6.0 with hydrochloric acid or sodium hydroxide aqueous solution and stir for about 1 minute.
(4) Add 2-3 drops of toluidine blue indicator and stir.
(5) Titrate with N/400 polyvinyl potassium sulfate reagent (N/400 PVSK). The titration speed is about 2 mL/min. The end point is the point at which the color of the sampled water changes from blue to reddish purple and is maintained for 10 seconds or longer.
(6) Colloid equivalent value (meq/g [pure]) = PVSK titer (mL) x PVSK factor/2/0.4
2. Analysis method of anion colloid equivalent value (1) Evaporation residue (% by weight) of a sample is measured in advance.
(2) Add "pure water: 95 mL" and "N/200-methyl glycol chitosan (MGK) aqueous solution: 5.0 mL" to a beaker, then add "0.1N NaOH: 0.5 mL" and stir for 1 minute. do.
(3) Add 5.0 mL of the sample diluted to 1,000 mg/L as solid content to (2) and stir for 5 minutes.
(4) Add 2-3 drops of toluidine blue indicator and stir.
(5) Titrate with N/400 polyvinyl potassium sulfate reagent (N/400 PVSK). The titration speed is about 2 mL/min. The end point is the point at which the color of the sampled water changes from blue to reddish purple and is maintained for 10 seconds or longer.
(6) A blank test (pure water: 100 mL) is performed in the same manner as the above operation.
(7) Colloid equivalent value (meq/g [pure]) = (blank titer (mL) - sample titer (mL)) x PVSK factor/2/evaporation residue (%) x 100

< Reference example 1>
Solubility CODMn is 264 mg / L, TOC 190 mg / L chemical factory wastewater, using a polyvinylidene fluoride (PVDF) ultrafiltration membrane (UF membrane) with a filtration membrane pore size of 0.1 μm, solubility CODMn is 10 times and the concentrated water was biologically treated by the activated sludge method. After that, measure 1 L of the biologically treated water, add 800 mg/L of polyaluminum chloride (PAC) as an inorganic coagulant, add sodium hydroxide or hydrochloric acid as a pH adjuster so that the pH becomes 7, and rapidly at 150 rpm for 10 minutes. Agitation was performed. Next, as a polymer flocculant, an acrylamide/acrylate copolymer (hereinafter referred to as polymer flocculant a) (anion colloid equivalent value: 50 meq/g, viscosity of 0.1% by weight aqueous solution: 50 mPa s (25° C.)) was added at 1 mg/L and slowly stirred at 40 rpm for 5 minutes. After stirring, the treated water was filtered through a quantitative filter paper (manufactured by ADBANTEC, No. 5A), and the CODMn (mg/L) and chromaticity of the filtrate were measured. In addition, the CODMn of the concentrated water after the concentration treatment, the CODMn of the biologically treated water after the biological treatment, and the chromaticity of the biologically treated water were also measured. Chromaticity is measured using a chromaticity meter (manufactured by Nippon Denshoku Industries Co., Ltd., Water Analyzer 2000N) based on the factory wastewater test method (JIS K 0101) "Method by stimulation value Y and chromaticity coordinates x, y". bottom. Table 1 shows the results.

<Example 2>
Before the polymer flocculant of Reference Example 1 was added, a 40% by weight aqueous solution of the organic coagulant had a viscosity of 11,000 mPa·s (25° C.) and a cationic colloid equivalent value of 6.2 meq/g (pH 6). The same treatment as in Reference Example 1 was performed except that 20 mg / L of polydiallyldimethylammonium chloride (hereinafter referred to as organic coagulant A) was added, and concentrated water, biologically treated water, and filtrate of treated water of CODMn was measured. Organic coagulant A is a polymer (X is a chloride ion) containing the structure shown in formula (5) above, and has a weight average molecular weight of about 600,000. Table 1 shows the results.

< Reference example 3>
As an organic coagulant, dimethylamine/epichlorohydrin/ammonia having a viscosity of 1,170 mPa·s (25° C.) in a 50 wt % aqueous solution and a cationic colloid equivalent value of 6.7 meq/g (pH 6) Except for changing to a condensate (hereinafter referred to as organic coagulant B), the same treatment as in Example 2 was performed, and the CODMn of the concentrated water, the biologically treated water, and the filtrate of the treated water was measured. Organic coagulant B is a polymer having a structure represented by formula (1) and formula (2) above, and has a weight average molecular weight of about 100,000. Table 1 shows the results.

<Example 4>
As an organic coagulant, a dimethylamine/epichlorohydrin/ethylenediamine condensate having a viscosity of 920 mPa·s (25° C.) in a 50% by weight aqueous solution and a cationic colloid equivalent value of 6.5 meq/g (pH 6). (Hereinafter referred to as organic coagulant C.) The same treatment as in Example 2 was performed, and the CODMn of the concentrated water, the biologically treated water, and the filtrate of the treated water was measured. Organic coagulant C is a polymer having the structure shown in formula (1) and formula (3) above, and has a weight average molecular weight of about 80,000. Table 1 shows the results.

<Example 5>
As an organic coagulant, a copolymer of diallyldimethylammonium halide and diallylamine having a viscosity of 200 mPa·s (25° C.) in a 35% by weight aqueous solution and a cationic colloid equivalent value of 6.0 meq/g (pH 6) (Diallyl (3-chloro-2-hydroxypropyl)amine hydrochloride-diallyldimethylammonium copolymer, CAS number: 75665-34-8) (hereinafter referred to as organic coagulant D), and the chromaticity was measured. The same treatment as in Example 2 was carried out, except that it was not used, and the CODMn of the concentrated water, the biologically treated water, and the filtrate of the treated water was measured. The organic coagulant D is a polymer having a structure represented by formula (6) above and having a weight average molecular weight of about 40,000. Table 1 shows the results.

<Example 6>
As an organic coagulant, polyethyleneimine (hereinafter referred to as organic coagulant E ) and that the chromaticity was not measured, the same treatment as in Example 2 was performed, and the CODMn of the concentrated water, the biologically treated water, and the filtrate of the treated water was measured. The organic coagulant E is a polymer having the structure shown in formula (4) above and has a weight average molecular weight of about 200,000. Table 1 shows the results.

<Example 7>
As an organic coagulant, polyamidine having a viscosity of 0.2% by weight salt of 35 mPa·s or more and a cationic colloid equivalent value of 6.0 meq/g or more (pH 6) (hereinafter referred to as organic coagulant F). ) and the chromaticity was not measured, the same treatment as in Example 2 was performed, and the CODMn of the concentrated water, the biologically treated water, and the filtrate of the treated water was measured. The organic coagulant F is a polymer having a structure represented by formula (7) above and having a weight average molecular weight of about 1,000,000. Table 1 shows the results.

<Comparative Example 1>
Except that no coagulant (inorganic coagulant, organic coagulant, polymer coagulant) was added and the chromaticity was not measured, the same treatment as in Example 2 was performed, and concentrated water and biological treatment were performed. The CODMn of water and filtrate of treated water was measured. Table 1 shows the results.

<Comparative Example 2>
The same treatment as in Reference Example 1 was performed except that the biological treatment was performed without concentrating the wastewater and the chromaticity was not measured, and the CODMn of the biologically treated water and the filtrate of the treated water was measured. . Table 1 shows the results.

<Comparative Example 3>
The same treatment as in Reference Example 3 was performed except that the biological treatment was performed without concentrating the wastewater and the chromaticity was not measured, and the CODMn of the biologically treated water and the filtrate of the treated water was measured. . Table 1 shows the results.

By performing the biological treatment after the concentration treatment and then performing the coagulation-sedimentation treatment, it was possible to efficiently reduce the amount of organic substances in the organic matter-containing water, compared to the case where the treatment was performed without performing the concentration treatment. In particular, the performance of reducing organic substances in treated water obtained by flocculation treatment using an organic flocculating agent in combination with an inorganic flocculant or a polymer flocculant was high.

When the CODMn reduction rate ({1-[CODMn concentration after coagulation sedimentation (mg/L)/CODMn concentration after biological treatment (mg/L)]}×100) is calculated, it is 52% in Comparative Example 2. Reference Since Example 1 is 63%, Comparative Example 2 has a lower organic matter reduction performance than Reference Example 1, and because no concentration treatment is performed, the treatment reaction tank becomes large, and the equipment cost increases. The CODMn reduction rate in Comparative Example 3 was 58 % , Reference Example 1 was 63%, and Reference Example 3 was 70%. As in , since no concentration treatment is performed, the size of the treatment reaction tank is increased and the facility cost is increased.

As described above, the organic matter in the organic matter-containing water could be efficiently reduced by the method of the example.

1 water treatment device 10 concentrator 12 biological treatment device 14 first reaction tank 16 second reaction tank 18 sedimentation tank 20 water to be treated pipe 22 concentrated water pipe 24 biologically treated water pipe 26 first reaction water pipe, 28 second reaction water pipe, 30 treated water pipe, 32 sludge discharge pipe, 34 inorganic coagulant addition pipe, 36 organic coagulant addition pipe, 38 pH adjuster addition pipe, 40 polymer coagulant addition pipe, 42, 44 Agitator.

Claims (6)

A concentration step of concentrating organic matter-containing water containing organic matter by a membrane separation treatment using a microfiltration membrane or an ultrafiltration membrane;
A biological treatment step of biologically treating the concentrated water obtained in the concentration step;
An inorganic coagulant, an organic coagulant (excluding dimethylamine/epichlorohydrin/ammonia condensate) and a polymer coagulant are added to the biologically treated water treated in the biological treatment process, and coagulation sedimentation treatment is performed. A coagulation sedimentation step of obtaining treated water by
including
The soluble CODMn of the concentrated water is 1000 mg/L or more,
A water treatment method, wherein the cationic colloid equivalent at pH 6 of the organic coagulant is 6.0 meq/g or more. The water treatment method according to claim 1,
A water treatment method, wherein the organic coagulant is a polyamine polymer. The water treatment method according to claim 2,
The polyamine-based polymer is a dimethylamine/epichlorohydrin/ethylenediamine condensate, polyethyleneimine, a diallyldimethylammonium halide polymer or a crosslinked polymer thereof, a copolymer of diallyldimethylammonium halide and diallylamine or a copolymer thereof. A water treatment method characterized by using at least one of a combined crosslinked product and a polyamidine. Concentrating means for concentrating organic matter-containing water containing organic matter by membrane separation treatment using a microfiltration membrane or an ultrafiltration membrane;
a biological treatment means for biologically treating the concentrated water obtained by the concentration means;
An inorganic coagulant, an organic coagulant (excluding dimethylamine/epichlorohydrin/ammonia condensate) and a polymer coagulant are added to the biologically treated water treated by the biological treatment means, and coagulation sedimentation is performed. A coagulating sedimentation means for obtaining treated water by
has
The soluble CODMn of the concentrated water is 1000 mg/L or more,
A water treatment apparatus, wherein the cationic colloid equivalent value at pH 6 of the organic coagulant is 6.0 meq/g or more. The water treatment device according to claim 4,
A water treatment device, wherein the organic coagulant is a polyamine polymer. The water treatment device according to claim 5,
The polyamine-based polymer is a dimethylamine/epichlorohydrin/ethylenediamine condensate, polyethyleneimine, a diallyldimethylammonium halide polymer or a crosslinked polymer thereof, a copolymer of diallyldimethylammonium halide and diallylamine or a copolymer thereof. A water treatment device comprising at least one of a combined crosslinked product and a polyamidine.

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