JP6738492B2 - Water treatment method and water treatment device - Google Patents

Description

The present invention relates to a water treatment method and a water treatment apparatus for reducing the COD of soluble COD-containing water containing soluble COD components discharged from factories such as chemical industry, paper/pulp, printing, machinery, foods, and pharmaceuticals. Regarding technology.

Waste water of various properties is discharged from chemical factories, paper/pulp factories, printing factories, machine manufacturing factories, food factories, pharmaceutical factories, etc. These wastewaters contain organic matter whose index is the chemical oxygen demand (COD), and if the COD component is discharged as it is, it may cause environmental pollution. Therefore, in the Water Pollution Control Law, a uniform drainage standard is set for the COD concentration of wastewater discharged from business sites with specific facilities to the sea area, lakes and marshes, and it is possible to reduce the COD concentration to below the drainage standard. It has been demanded.

In addition, in areas where the prevention of water pollution is insufficient with uniform drainage standards alone, prefectures have established additional drainage standards by ordinance. The COD additional drainage standard varies depending on the type of industry and region, but in some cases, a strict standard of 20 mg/L or less is set.

Therefore, biological treatment is mainly applied to reduce the COD of wastewater. However, some wastewater has a property that COD cannot be sufficiently reduced by biological treatment alone. In this case, the main cause is that the waste water is hardly biodegradable and contains a soluble COD component. Therefore, physicochemical treatments such as flocculation treatment, Fenton treatment, ozone treatment and activated carbon treatment are carried out in order to reduce the COD component which is hardly biodegradable and soluble.

The coagulation treatment is effective for removing the COD component derived from the suspended substance, but the reduction rate of the soluble COD component is low, and it is necessary to add a large amount of the coagulant to satisfy the regulation value. There is. As described above, the removal of the COD component which is hardly biodegradable and soluble has become a major issue.

In addition, COD may be reduced by adsorption of activated carbon in the latter stage of the coagulation treatment. The activated carbon treatment is also effective in reducing the soluble COD component, but when the reduction of the soluble COD component in the coagulation treatment is insufficient, it is necessary to frequently replace the activated carbon, which raises a running cost. ..

On the other hand, oxidation treatments such as Fenton treatment and ozone treatment are also effective in reducing soluble COD components. However, the Fenton treatment consumes a large amount of chemicals such as hydrogen peroxide, ferrous sulfate, and a pH adjuster, and generates a large amount of sludge, so it is hard to say that it is an economical wastewater treatment method in terms of running cost. Further, the ozone treatment has a problem in that the ozone generator is expensive and peripheral equipments such as an oxygen generator and a waste ozone decomposer are required, so that the initial cost is high.

In order to solve these problems, the coagulation treatment performance has been improved. For example, Patent Document 1 proposes a method of reducing the soluble COD component by adding organic fine particles having a cationic functional group capable of adsorbing the COD component in the coagulation sedimentation treatment. However, this method cannot be said to be an economical treatment method in that a large amount of sludge is generated, because the concentration of the organic fine particles added is as high as 500 to 3000 mg/L in terms of solid content and the organic fine particles directly become sludge. Furthermore, since the aliphatic hydrocarbon liquid and the surfactant are added to the chemicals in order to disperse the organic fine particles, there is a concern that these additives may remain in the liquid to be treated.

Further, in Patent Document 2, in the aggregating treatment, a cationic polymer electrolyte having a weight average molecular weight of 10,000 or more and 1,000,000 or less is added after the addition of an anionic polymer electrolyte having a weight average molecular weight of 1,000 or more. A method for removing the characteristic COD component has been proposed. However, the removal performance of COD components in wastewater other than the pulp and paper mill shown in the example of Patent Document 2 is unknown, and it cannot be said that the treated water COD of the wastewater can be reduced to a sufficiently low concentration. ..

Patent Document 3 proposes a coagulation treatment method in which an amphoteric organic coagulant having a copolymerization ratio of an anionic monomer to a cationic monomer in a range of 0.1 to 3 mass% is added. However, as shown in the examples of Patent Document 3, although it is effective in reducing the turbidity of the papermaking industry wastewater containing a suspended substance at a high concentration, the treatment performance of soluble COD components is not clear. Absent.

Patent Document 4 proposes a papermaking wastewater treatment method in which a coagulant is added to wastewater biologically treated in a fluidized bed biological reaction tank, and then a cationic polymer flocculant is added to perform coagulation treatment. However, in Patent Document 4, the soluble COD component of the biologically treated water used as the raw water for the coagulation treatment is unknown, and the treatment performance of the soluble COD component is not clear.

Although it is possible to reduce the COD of wastewater by the conventional technology, it cannot be said that the treatment performance of the hardly biodegradable soluble COD component is sufficient. Further, if the coagulation treatment using the organic fine particles described in Patent Document 1 or the known powdered activated carbon is performed, it is possible to reduce the hardly biodegradable soluble COD component, but these solid adsorbents Requires a large amount to be added, and there is a problem of increasing the amount of sludge generated. As described above, in the related art, there is a concern that wastewater treatment cost increases because the soluble COD component is reduced.

Japanese Patent No. 4923834 JP, 2009-154095, A Japanese Patent No. 5560626 JP, 2014-028365, A

An object of the present invention is to provide a water treatment method and a water treatment apparatus capable of reducing the amount of a hardly biodegradable soluble COD component while suppressing the amount of sludge generated in the coagulation treatment of COD-containing water containing a soluble COD component. To provide.

The present invention includes a coagulation treatment step of adding a COD reducing agent to COD-containing water containing a soluble COD component to perform coagulation treatment, and the COD reducing agent has a viscosity of a 50 wt% aqueous solution of 1,000 mPa· s or greater, and, seen containing a dimethylamine-epichlorohydrin-ammonia condensate is cationic colloidal equivalent value 6.0 meq / g or more (pH 6), in front of the aggregation treatment step, the water to be treated A water treatment method comprising a biological treatment step of biological treatment, wherein the COD-containing water is the biological treated water obtained in the biological treatment step .

In the water treatment method, the solubility CODMn of the COD-containing water is preferably 20 mg/L or more.

In the water processing method, in front of the biological treatment step, wherein the concentration step of concentrating the organic substance-containing water containing organic matter, in the biological treatment step, to a biological treatment concentrated water obtained in the concentration step Turkey And are preferred.

In the biological treatment step in the water treatment method, biological treatment is preferably performed by a membrane separation activated sludge method.

Further, the present invention comprises a coagulation treatment means for performing a coagulation treatment by adding a COD reducing agent to COD-containing water containing a soluble COD component, wherein the COD reducing agent has a viscosity of a 50% by weight aqueous solution of 1,000. and in mPa · s or more and the cationic colloidal equivalent value observed contains a dimethylamine epichlorohydrin-ammonia condensate is 6.0 meq / g or more (pH 6), in front of said aggregate processing unit, the processed A water treatment device comprising a biological treatment means for biologically treating water, wherein the COD-containing water is the biological treated water obtained by the biological treatment means .

In the water treatment device, the solubility CODMn of the COD-containing water is preferably 20 mg/L or more.

In the water treatment apparatus, in front of the biological treatment unit comprises a concentration means for concentrating the organic substance-containing water containing organic matter, the biological treatment means, the concentrated water obtained by the concentrating means intended to biological treatment It is preferable to have.

In the water treatment device, the biological treatment means preferably performs biological treatment by a membrane separation activated sludge method.

According to the present invention, in the coagulation treatment of COD-containing water containing a soluble COD component, a water treatment method and a water treatment apparatus capable of reducing the hardly biodegradable soluble COD component while suppressing the amount of sludge generated. Can be provided.

It is a schematic structure figure showing an example of the water treatment equipment concerning the embodiment of the present invention. It is a schematic block diagram which shows the other example of the water treatment apparatus which concerns on embodiment of this invention.

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

An outline of an example of the water treatment device according to the embodiment of the present invention is shown in FIG. 1, and its configuration will be described. The water treatment device 1 shown in FIG. 1 includes a flocculation device 10 and a settling tank 12. The aggregating apparatus 10 includes a first reaction tank 14, a second reaction tank 16, and an aggregating tank 18. The first reaction tank 14 includes a COD reducing agent addition line 20, the second reaction tank 16 includes an inorganic coagulant addition line 22 and a pH adjusting agent addition line 24, and the coagulation tank 18 includes a polymer coagulant addition line. 26 is provided. The first reaction tank 14, the second reaction tank 16, and the coagulation tank 18 are provided with a stirrer 28 having a stirring blade, a stirrer 30, and a stirrer 32, respectively, as stirring means.

In the water treatment device 1 shown in FIG. 1, a treated water inflow line 34 is connected to the water inlet of the first reaction tank 14. A COD reducing agent addition line 20 is connected to the chemical inlet of the first reaction tank 14. The water outlet of the reaction tank 14 is connected to one end of a water discharge line 36, and the water inlet of the second reaction tank 16 is connected to the other end of the water discharge line 36.

An inorganic coagulant addition line 22 and a pH adjusting agent addition line 24 are connected to the chemical inlet of the second reaction tank 16. Further, one end of a water discharge line 38 is connected to the water outlet of the second reaction tank 16, and the other end of the water discharge line 38 is connected to the water inlet of the coagulation tank 18.

A polymer coagulant addition line 26 is connected to the medicine inlet of the coagulation tank 18. Further, one end of a water discharge line 40 is connected to the water outlet of the aggregation tank 18, and the other end of the water discharge line 40 is connected to the water inlet of the settling tank 12.

A treated water discharge line 42 is connected to the treated water outlet of the settling tank 12, and a sludge discharge line 44 is connected to the sludge discharge port of the settling tank 12.

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

The COD-containing water that is the water to be treated and that contains the soluble COD component is supplied to the first reaction tank 14 through the water-to-be-treated inflow line 34, and the COD reducing agent is supplied from the COD reducing agent addition line 20 It is supplied to one reaction tank 14 (COD reducing agent supply step). The water to be treated and the COD reducing agent in the first reaction tank 14 are stirred by the stirrer 28, and the soluble COD component is insolubilized (insolubilization step).

Here, the COD reducing agent is a polyamine polymer having a viscosity of 500 mPa·s or more in a 50 wt% aqueous solution and a cationic colloid equivalent value of 6.0 meq/g or more (pH 6), a viscosity of a 40 wt% aqueous solution. Is 1,500 mPa·s or more, and the cationic colloid equivalent value is 6.0 meq/g or more (pH 6), and the viscosity of the 40 wt% aqueous solution is 5,000 mPa·s or more, and And at least one of polydiallyldimethylammonium chloride having a cationic colloid equivalent value of 6.0 meq/g or more (pH 6).

Soluble COD components, as well as negatively charged, -OH in the molecule, _-COOH, since having -NH 2, hydrophilic functional groups -NH- etc., in a state dispersed and dissolved in water However, since the COD reducing agent is a compound having a positive charge in the molecular structure and having a high cation density, the negative charge of the soluble COD component is neutralized by adding the COD reducing agent to the COD-containing water. It is considered that the property tends to cause aggregation. Further, among the above COD reducing agents, the polyamine-based polymer having a secondary amine —NH—, —OH, or the like in the molecule forms a hydrogen bond with the hydrophilic functional group of the soluble COD component to dissolve. It is presumed that the soluble COD component is easily insolubilized.

The insolubilized COD-containing water containing the insolubilized COD component is supplied from the first reaction tank 14 to the second reaction tank 16 through the water discharge line 36, and the inorganic coagulant is added from the inorganic coagulant addition line 22 to pH. The adjusting agent is supplied from the pH adjusting agent adding line 24 to the second reaction tank 16 (inorganic coagulant adding step). The insolubilized COD-containing water, the inorganic coagulant and the pH adjuster in the second reaction tank 16 are stirred by the stirrer 30. The inorganic coagulant adjusted to a predetermined pH becomes a metal hydroxide, and fine flocs are formed together with the insolubilized COD component (floc forming step).

The fine floc-containing water containing fine flocs is supplied from the second reaction tank 16 to the coagulation tank 18 through the water discharge line 38, and the polymer coagulant is supplied from the polymer coagulant addition line 26 to the coagulation tank 18. (Polymer flocculant addition step). The fine floc-containing water and the polymer flocculant in the flocculation tank 18 are agitated by the agitator 32. The polymer flocculant associates the fine flocs with each other to grow the flocs (floc growth step).

The floc-containing water containing flocs is supplied from the flocculation tank 18 to the settling tank 12 through the water discharge line 40. In the settling tank 12, solid-liquid separation is performed into the treated water and flocs by natural sedimentation or the like (solid-liquid separation step). Then, the treated water with reduced soluble COD components is discharged from the treated water discharge line 42, and the flocs are discharged from the sludge discharge line 44 as sludge.

In the water treatment method and the water treatment apparatus according to the present embodiment, by using the COD reducing agent, the amount of chemicals used in the coagulation treatment of the hardly biodegradable soluble COD component is suppressed, and sludge generation in the coagulation treatment occurs. The refractory biodegradable soluble COD component can be reduced while suppressing the amount. Further, the amount of chemicals consumed and the amount of sludge generated are small, which is an economical method in terms of initial cost and running cost. Further, it is excellent in floc formation in flocculation treatment, floc sedimentation property and appearance of treated water.

The outline of another example of the water treatment device according to the embodiment of the present invention is shown in FIG. 2, and the configuration thereof will be described. The water treatment device 3 shown in FIG. 2 has a concentrating device 50 as a concentrating means, a biological treating device 52 as a biological treating means, and a flocculation having a first reaction tank 54, a second reaction tank 56 and a precipitation tank 58 as a flocculating treatment means. And a processing device. The water treatment device 3 may include a to-be-treated water tank (not shown) for storing the to-be-treated water in the preceding stage of the concentrating device 50.

In the water treatment device 3 shown in FIG. 2, the treated water inflow line 60 is connected to the inlet of the concentrating device 50. The outlet of the concentrating device 50 and the inlet of the biological treatment device 52 are connected by a concentrated water line 62. The outlet of the biological treatment device 52 and the inlet of the first reaction tank 54 are connected by a biological treated water line 64. The outlet of the first reaction tank 54 and the inlet of the second reaction tank 56 are connected by a water discharge line 66. The outlet of the second reaction tank 56 and the inlet of the precipitation tank 58 are connected by a water discharge line 68. A treated water discharge line 70 is connected to the treated water outlet of the settling tank 58, and a sludge discharge line 72 is connected to the lower sludge outlet. An inorganic coagulant addition line 74, a COD reducing agent addition line 76, a pH adjusting agent addition line 78 are connected to the first reaction tank 54, and a stirrer 82 having a stirring blade or the like may be installed. A polymer coagulant addition line 80 may be connected to the second reaction tank 56, and a stirrer 84 having a stirring blade or the like may be installed.

An example of the operation of the water treatment method and the water treatment apparatus 3 according to this embodiment will be described.

The organic substance-containing water, which is the water to be treated and which contains the organic matter, is stored in the treated water tank as necessary and then supplied to the concentrator 50 through the treated water inflow line 60. In the concentration device 50, the organic substance-containing water is concentrated (concentration step). The concentrated water obtained in the concentration step is supplied to the biological treatment device 52 through the concentrated water line 62. In the biological treatment device 52, the concentrated water is biologically treated (biological treatment step).

Next, a flocculant is added to the biological treated water treated in the biological treatment step, and treated water is obtained by the coagulation treatment (aggregation treatment step). The aggregation treatment step is specifically as follows, for example.

The biologically treated water treated in the biological treatment step is supplied from the biologically treated device 52 to the first reaction tank 54 through the biologically treated water line 64. In the first reaction tank 54, the inorganic coagulant is added through the inorganic coagulant addition line 74 (inorganic coagulant addition step) and the COD reducing agent is added through the COD reducing agent addition line 76 (COD reducing agent addition step). The biologically treated water, the inorganic coagulant, and the COD reducing agent in the first reaction tank 54 are stirred by the stirrer 82 to insolubilize the organic matter (insolubilization step). If necessary, a pH adjusting agent may be added to the first reaction tank 54 through the pH adjusting agent adding line 78 to adjust the pH (pH adjusting step). The inorganic coagulant adjusted to a predetermined pH becomes, for example, a metal hydroxide, and fine flocs are formed together with the insolubilized organic matter (floc formation step).

Here, the COD reducing agent is a polyamine polymer having a viscosity of 500 mPa·s or more in a 50 wt% aqueous solution and a cationic colloid equivalent value of 6.0 meq/g or more (pH 6), a viscosity of a 40 wt% aqueous solution. Is 1,500 mPa·s or more, and the cationic colloid equivalent value is 6.0 meq/g or more (pH 6), and the viscosity of the 40 wt% aqueous solution is 5,000 mPa·s or more, and And at least one of polydiallyldimethylammonium chloride having a cationic colloid equivalent value of 6.0 meq/g or more (pH 6).

The first reaction water containing fine flocs (fine floc-containing water) is supplied from the first reaction tank 54 to the second reaction tank 56 through the water discharge line 66. In the second reaction tank 56, the polymer coagulant is added through the polymer coagulant addition line 80 (polymer coagulant addition step). The fine floc-containing water and the polymer flocculant in the second reaction tank 56 are agitated by the agitator 84. The polymer flocculant associates the fine flocs with each other to grow the flocs (floc growth step).

The second reaction water containing flocs (flock-containing water) is supplied from the second reaction tank 56 to the settling tank 58 through the water discharge line 68. In the settling tank 58, the treated water and flocs are solid-liquid separated by natural sedimentation or the like (solid-liquid separation step). Then, the treated water with reduced organic matter is discharged through the treated water discharge line 70, and the flocs are discharged as sludge through the sludge discharge line 72.

The present inventors obtain concentrated water by concentrating organic matter-containing water, biologically treat the concentrated water, and then perform coagulation treatment to remove organic matter such as COD components and pigments, and turbidity. It has been found that the contained organic matter-containing water exhibits good coagulation treatment performance and can effectively reduce organic matter and the like.

By performing the biological treatment after the concentration treatment, the decomposition products are different from those when the biological treatment is performed without the concentration treatment. Cheap. This is because the biologically treated water that has been subjected to the biological treatment after the concentration treatment has more negatively charged chemical substances, so that the inorganic flocculant, the COD reducing agent, or the polymer flocculant is used. It is presumed that the shape is easily neutralized by the aggregating agent and easily aggregates.

Various methods may be used for the concentration in the concentration step, and for example, the concentration may be performed using an evaporation process, a membrane filtration process, or the like.

Examples of the evaporation treatment include natural evaporation, heating evaporation, spray evaporation, vacuum evaporation and the like.

The membrane used for the membrane filtration treatment is not particularly limited, but a microfiltration membrane (MF membrane), an ultrafiltration membrane (UF membrane), a nanofiltration membrane (NF membrane), a reverse osmosis membrane (RO membrane), etc. may be used. Can be mentioned. Microfiltration membrane (MF membrane), ultrafiltration membrane (UF membrane), and nanofiltration membrane (NF membrane) are preferable from the viewpoints of effective concentration, and microfiltration membrane (MF membrane), ultrafiltration membrane An ultrafiltration membrane (UF membrane) is more preferable, and an ultrafiltration membrane (UF membrane) is even more preferable. A reverse osmosis membrane (RO membrane) with a small separation particle size is likely to clog the membrane, and a microfiltration membrane (MF membrane) has a large separation particle size and is less likely to be concentrated than other membranes, resulting in organic matter after aggregation. 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, but for example, an organic membrane such as polyvinylidene fluoride (PVDF), polyvinyl chloride (PVC), polyether sulfone (PES), cellulose acetate (CA), or an inorganic material such as ceramics. Examples include membranes.

The shape of the filtration membrane is not particularly limited, but may be, for example, a hollow fiber membrane, a tubular membrane, a flat membrane, a spiral, or the like. The water flow system of the filtration membrane is not particularly limited, 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 treatment for biologically oxidizing or reducing organic matter in concentrated water by microorganisms such as aerobic microorganisms and anaerobic microorganisms. For example, standard activated sludge method, biofilm method, membrane separation activated sludge method (MBR) , Fixed bed method, fluidized bed method and the like.

As a polyamine-based polymer having a viscosity of 500 mPa·s or more of a 50 wt% aqueous solution, which is a COD reducing agent, and a cationic colloid equivalent value of 6.0 meq/g or more (pH 6), dimethylamine/epichlorohydride is used. Examples thereof include phosphorus/ammonia condensate, dimethylamine/epichlorohydrin/ethylenediamine condensate, and the like. The viscosity of a 50% by weight aqueous solution of a dimethylamine/epichlorohydrin/ammonia condensate may be 500 mPa·s or more and is not particularly limited, but is preferably 800 mPa·s or more, and 1,000 mPa·s or more. It is more preferable if The upper limit of the viscosity of the 50 wt% aqueous solution is not particularly limited, but it is preferably 4,000 mPa·s or less, and more preferably 2,000 mPa·s or less. The cationic colloid equivalent value may be 6.0 meq/g or more (pH 6) and is not particularly limited, but it is preferably 6.5 meq/g or more (pH 6).

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

The viscosity of a 40% by weight aqueous solution of polyethyleneimine, which is a COD reducing agent, may be 1,500 mPa·s or more and is not particularly limited, but it is more preferably 2,000 mPa·s or more. The upper limit of the viscosity of the 40 wt% aqueous solution is not particularly limited, but it is preferably 4,000 mPa·s or less. The cationic colloid equivalent value may be 6.0 meq/g or more (pH 6) and is not particularly limited, but it is preferably 6.5 meq/g or more (pH 6).

The viscosity of a 40% by weight aqueous solution of polydiallyldimethylammonium chloride, which is a COD reducing agent, may be 5,000 mPa·s or more and is not particularly limited, but it is more preferably 8,000 mPa·s or more. The upper limit of the viscosity of the 40 wt% aqueous solution is not particularly limited, but it is preferably 15,000 mPa·s or less. The cationic colloid equivalent value may be 6.0 meq/g or more (pH 6) and is not particularly limited, but it is preferably 6.2 meq/g or more (pH 6).

Of these, dimethylamine-epichlorohydrin-ammonia condensate or dimethylamine-condensate having a viscosity of a 50% by weight aqueous solution and a cationic colloid equivalent value within the above ranges from the viewpoint of high effect of reducing soluble COD components. Polyethyleneimine having an epichlorohydrin-ethylenediamine condensate and a 40 wt% aqueous solution having a viscosity and a cationic colloid equivalent value within the above ranges is preferable, and a 50 wt% aqueous solution having a viscosity and a cationic colloid equivalent value within the above range are preferred. Epichlorohydrin-ammonia condensate or dimethylamine-epichlorohydrin-ethylenediamine condensate is more preferable.

Here, the viscosity of the 40 wt% aqueous solution or the 50 wt% aqueous solution is an index representing the molecular weight of the compound, and the larger the value, the higher the molecular weight of the compound. The viscosity of the 40 wt% aqueous solution or the 50 wt% aqueous solution is measured by a viscometer such as a Brookfield type rotational viscometer.

The cationic colloid equivalent value is an index showing the strength of the positive charge in the compound, and the larger the value, the stronger the positive charge of the compound. The cationic colloid equivalent value is determined by the colloid titration method. Specifically, the aqueous solution in which the drug is dispersed is titrated with a polyvinyl potassium sulfate solution. The solution pH at the time of titration is 4 to 10.

で表される構造、および、下記式（２）

で表される構造を含むポリマーである。上記ポリマーでは、式（２）で表される構造と式（１）で表される構造の割合が、モル比（式（２）で表される構造：式（１）で表される構造）で例えば０．０１：９．９９〜７：３であればよい。Dimethylamine-epichlorohydrin-ammonia condensate has the following formula (1)

And a structure represented by the following formula (2)

It is a polymer containing a structure represented by. In the above polymer, the ratio of the structure represented by the formula (2) to the structure represented by the formula (1) is in a molar ratio (structure represented by the formula (2):structure represented by the formula (1)). Then, it may be, for example, 0.01:9.99 to 7:3.

で表される構造を含むポリマーである。上記ポリマーでは、式（３）で表される構造と式（１）で表される構造の割合が、モル比（式（３）で表される構造：式（１）で表される構造）で例えば０．０１：９．９９〜７：３であればよい。The dimethylamine/epichlorohydrin/ethylenediamine condensate has a structure represented by the formula (1) and the following formula (3)

It is a polymer containing a structure represented by. In the above polymer, the ratio of the structure represented by the formula (3) and the structure represented by the formula (1) is in a molar ratio (structure represented by the formula (3):structure represented by the formula (1)). Then, it may be, for example, 0.01:9.99 to 7:3.

で表される構造を含むポリマーである。Polyethyleneimine has the following formula (4)

It is a polymer containing a structure represented by.

で表される構造を含むポリマーである。Polydiallyl dimethyl ammonium chloride has the following formula (5)

It is a polymer containing a structure represented by.

In the water treatment method and the water treatment apparatus according to the present embodiment, the addition amount of the COD reducing agent is a weight ratio of the addition amount of the COD reducing agent to the addition amount of the inorganic coagulating agent (addition amount of COD reducing agent/inorganic coagulating agent). The amount added) is preferably 0.1 or less, and more preferably 0.002 or more and 0.07 or less. If this weight ratio exceeds 0.1, the amount of the COD reducing agent added becomes excessive, and the treated water quality may deteriorate compared to the optimum conditions. If it is less than 0.002, the COD component reducing effect is exhibited. May not be. The addition amount of the COD reducing agent may be set to an optimum addition amount by a jar test or the like.

The soluble COD-containing water containing the soluble COD component to be treated may be water of any origin and is not particularly limited, but for example, a chemical factory, a paper/pulp factory, a printing factory, a machine manufacturing factory, a food factory, Examples include drainage from pharmaceutical factories and the like, and examples thereof include saccharide-containing drainage, humic acid-containing drainage, and cloth processing drainage discharged from the above-mentioned various plants. The organic matter-containing water containing organic matter may be water of any origin as long as it is water containing organic matter such as chromaticity components such as pigments and soluble COD components, and is not particularly limited. Examples of the wastewater include pulp mills, printing mills, machine manufacturing mills, food mills, pharmaceutical mills, and the like, and examples thereof include saccharide-containing wastewater, humic acid-containing wastewater, cloth-processing wastewater, and the like discharged from the above-mentioned various plants. The soluble COD-containing water to be treated is a biological treatment such as activated sludge treated water obtained by treating the various wastewaters by the activated sludge method, and membrane separated activated sludge treated water obtained by treating the various wastewaters by the membrane separation activated sludge method. It may be water, and is particularly preferably applied to the membrane-separated activated sludge treated water of the above-mentioned various effluents from the viewpoint that the effect of reducing the soluble COD component by the COD reducing agent is high.

The solubility CODMn of the COD-containing water may be 20 mg/L or more, preferably 60 mg/L or more, and more preferably 90 mg/L or more. When the solubility CODMn of the COD-containing water is less than 20 mg/L, the effect of reducing the soluble COD component by the COD reducing agent may be reduced. Here, the solubility of COD-containing water COD refers to the COD of the filtrate after filtering the COD-containing water with a filter paper (No. 5C).

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

The chromaticity of the COD-containing water is, for example, in the range of 5 to 2,000 degrees.

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

The SS concentration of the COD-containing water is, for example, less than 300 mg/L. If the SS concentration of the COD-containing water exceeds 300 mg/L, the effect of reducing the soluble COD component by the COD reducing agent may be reduced.

Examples of the inorganic aggregating agent include iron-based inorganic aggregating agents such as ferric chloride and polyferric sulfate, and aluminum-based inorganic aggregating agents such as aluminum sulfate and polyaluminum chloride (PAC).

The addition amount of the inorganic coagulant is not particularly limited. Although it varies depending on the concentration of the suspended COD-containing water to be treated, the chromaticity and COD, the range of 50 to 5,000 mg/L is preferable.

The pH adjusting agent is an acid such as hydrochloric acid or sulfuric acid, or an alkali such as sodium hydroxide.

The pH may be adjusted within the range of 4 to 11, for example.

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

In the present embodiment, in order to perform better aggregation treatment, it is preferable to add a polymer flocculant to grow the floc diameter. From the viewpoint of performing a good coagulation treatment, it is preferable to add the polymer coagulant after the coagulation reaction with the COD reducing agent and the inorganic coagulant is completed. Specifically, the polymer flocculant may be added in the coagulation tank 18 in the latter stage of the second reaction tank 16 or in the second reaction tank 56 in the latter stage of the first reaction tank 54.

The polymer flocculant is not particularly limited, such as nonionic polymer flocculant, anionic polymer flocculant or cationic polymer flocculant, and examples thereof include polyacrylamide, sodium polyacrylate, and acrylamide propane. Examples thereof include sodium sulfonate, chitosan, dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate and polyamidine. The polymer flocculants may be used alone 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, and preferably in the range of 1,000,000 to 50,000,000.

The amount of the polymer flocculant added is not particularly limited, but is preferably in the range of 0.5 to 10 mg/L, for example.

After the addition of the polymer flocculant, it is preferable that the stirring speed is made gentle (for example, 20 to 50 rpm) to grow the floc diameter.

The liquid temperature in the aggregation 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.

The solid-liquid separation of the treated water and flocs after the coagulation treatment is not limited to the settling tank. The solid-liquid separation method is not particularly limited, and examples thereof include precipitation treatment, filtration treatment, and membrane separation treatment. The precipitation treatment is not particularly limited and may be, for example, a forced precipitation treatment using a centrifuge or the like, in addition to the natural precipitation treatment using a sedimentation tank. Further, the filtration treatment is not particularly limited, and examples thereof include a gravity type, a pressure type, a siphon type, an upflow type, a filter medium circulation type, a continuous filtration type, and an anthracite, sand, silica, gravel, activated carbon. It can be filtered using a filter material such as plastic. The membrane separation treatment is also not particularly limited, and for example, a microfiltration membrane, an ultrafiltration membrane or the like can be used for membrane separation.

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

The solubility CODMn of the treated water can be, for example, 20 mg/L or less by the water treatment method and the water treatment apparatus according to the present embodiment, and the chromaticity of the treated water can be, for example, 10 degrees or less. be able to.

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

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.

As the soluble COD-containing water to be treated in Examples and Comparative Examples, activated sludge treated water of sugar-containing wastewater, membrane separation activated sludge treated water of chemical factory wastewater, humic acid-containing wastewater and activated sludge treated water of cloth processing wastewater, The biofilm-treated water of the wastewater of the dairy manufacturing factory was used.

<Example 1-1>
250 mL of activated sludge treated water (solubility CODMn 94 mg/L, SS 20 mg/L or less) of sugar-containing wastewater was put in a glass beaker, and the viscosity of a 50 wt% aqueous solution as a COD reducing agent was 1,170 mPa·s (25° C.). 20 mg/L of dimethylamine-epichlorohydrin-ammonia condensate (hereinafter referred to as COD reducing agent A1) having a cationic colloid equivalent value of 6.7 meq/g (pH 6) as a solid content was added. And stirred for 10 minutes at a rotation speed of 150 rpm. The COD reducing agent A1 is a polymer containing the structures shown in the above formulas (1) and (2), and has a weight average molecular weight of about 100,000. Next, 400 mg/L of polyaluminum chloride (PAC) was added, caustic soda was added to adjust the pH to 7.0, and the mixture was stirred at a rotation speed of 150 rpm for 5 minutes. Thereafter, 2 mg/L of a polymer flocculant (anion colloid equivalent value: 50 meq/g, viscosity of 0.1 wt% aqueous solution: 50 mPa·s (25° C.)), which is an acrylamide/acrylic acid copolymer, was added. After stirring for 1 minute at a rotation speed of 150 rpm, the mixture was stirred at 40 rpm for 5 minutes to grow the floc diameter. The treated water after completion of stirring was filtered through a quantitative filter paper (No. 5A, manufactured by ADVANTEC), and CODMn of the filtrate was measured. CODMn was measured according to “Factory oxygen test method (JIS K 0102) “oxygen consumption by potassium permanganate at 100° C.”.

The viscosity of a 40% by weight aqueous solution or a 50% by weight aqueous solution of the COD reducing agent was measured using a Brookfield type rotational viscometer (DV-1 manufactured by Eiko Seiki Co., Ltd.).

The cationic colloid equivalent value of the COD reducing agent was determined by the following method by the colloid titration method. The solution pH at the time of titration was 6.0.

<Colloidal titration method>
1. Method of Analyzing Cation Colloid Equivalent Value (1) The evaporation residue (wt%) of the 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 the pH to 6.0 with hydrochloric acid or aqueous sodium hydroxide and stir for about 1 minute.
(4) Add 2-3 drops of toluidine blue indicator and stir.
(5) Titrate with N/400 polyvinyl potassium sulfate reagent (N/400 PVSK). The titration rate is about 2 mL/min. The end point is the point at which the test water is held for 10 seconds or longer after it changes from blue to magenta.
(6) Colloid equivalent value (meq/g [pure content])=PVSK titer (mL)×PVSK factor/2/0.4
2. Analytical Method of Anion Colloid Equivalent Value (1) The evaporation residue (wt %) of the sample is measured in advance.
(2) "Pure water: 95 mL" and "N/200-methyl glycol chitosan (MGK) aqueous solution: 5.0 mL" were added to a beaker, and then "0.1 N NaOH: 0.5 mL" was added and stirred for 1 minute. To do.
(3) To (2), 5.0 mL of a sample diluted to 1,000 mg/L as a solid content is added and stirred 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 rate is about 2 mL/min. The end point is the point at which the test water is maintained for 10 seconds or more after it changes from blue to magenta.
(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 content])=(blank titration amount (mL)-sample titration amount (mL))×PVSK factor/2/evaporation residue (%)×100

< Reference example 1-2>
The COD reducing agent A1 is a polyethyleneimine having a viscosity of 2,500 mPa·s (25° C.) in a 40% by weight aqueous solution and a cationic colloid equivalent value of 6.6 meq/g (pH 6) (hereinafter referred to as COD reducing agent. The same treatment as in Example 1-1 was carried out except that the CODMn of the treated water was measured. The COD reducing agent B is a polymer having a structure represented by the above formula (4) and has a weight average molecular weight of about 200,000.

<Comparative Example 1-1>
Dimethylamine-epichlorohydrin-ammonia condensation of COD reducing agent A1 in which 50% by weight aqueous solution has a viscosity of 70 mPa·s (25°C) and a cationic colloid equivalent value of 6.8 meq/g (pH 6) The same treatment as in Example 1-1 was carried out except that the product was changed to a product (hereinafter referred to as COD reducing agent A1′), and CODMn of the filtrate of the treated water was measured. The COD reducing agent A1′ is a polymer containing the structures represented by the above formulas (1) and (2), and has a weight average molecular weight of about 10,000.

<Comparative Example 1-2>
400 mg/L of PAC was added to the saccharide-containing wastewater without adding a COD reducing agent, caustic soda was added to adjust the pH to 7.0, and the mixture was stirred at a rotation speed of 150 rpm for 5 minutes. After that, the same treatment as in Example 1-1 was performed, and CODMn of the filtrate of the treated water was measured.

Table 1 shows the measurement results of CODMn of Examples and Comparative Examples. In addition, the floc formation, floc sedimentation property, and appearance of supernatant water (treated water) in the treatments of Examples and Comparative Examples were visually evaluated according to the following criteria. The evaluation criteria are the same for all the following examples and comparative examples.

(Flock formation)
Good: A flock of approximately 2 mm or more is formed.
Slightly defective: Flock of about 1 mm is formed.
Bad: Flock is hardly formed.

(Floc sedimentation)
Good: Most of the flocs settle within 3 minutes after completion of stirring.
Somewhat bad: Most of the flocs settle within 10 minutes after the completion of stirring.
Poor: Flock remains in the supernatant water even 10 minutes after the completion of stirring.

(Appearance of clear water)
Good: The supernatant water after standing for 30 minutes was clear and had almost no turbidity or chromaticity.
Somewhat poor: Some turbidity and chromaticity remain in the supernatant water after standing for 30 minutes.
Poor: Turbidity and chromaticity remain in the supernatant water after standing for 30 minutes.

As shown in Table 1, the CODMn of Example 1-1 in which the COD reducing agent A1 was added, the reference example 1-2 in which the COD reducing agent B was added, and the CODMn of Comparative example 1-1 in which the COD reducing agent A1′ was added are compared. Then, the COD was most favorably reduced in Example 1-1. Further, as compared with Comparative Example 1-2 in which the COD reducing agent was not added, Example 1-1 and Reference Example 1-2 were better.

Thus, it is clear that the COD reducing agent A1 and the COD reducing agent B have a COD reducing effect. Further, the COD reducing agent A1', which is a dimethylamine/epichlorohydrin/ammonia condensate, like the COD reducing agent A1, had a lower COD reducing effect than the examples. It is considered that the COD reducing agent A1' has a low viscosity.

< Reference example 2-1>
250 mL of activated sludge treated water (soluble CODMn 58 mg/L, SS 20 mg/L or less) of sugar-containing wastewater was put in a glass beaker, and a viscosity of a 50% by weight aqueous solution as a COD reducing agent was 920 mPa·s (25° C.), Moreover, 10 mg/L of a dimethylamine/epichlorohydrin/ethylenediamine condensate having a cationic colloid equivalent value of 6.5 meq/g (pH 6) (hereinafter referred to as COD reducing agent C1) was added as a solid content, It was stirred for 10 minutes at a rotation speed of 150 rpm. The COD reducing agent C1 is a polymer containing the structures represented by the above formulas (1) and (3) and has a weight average molecular weight of about 80,000. Next, 200 mg/L of PAC was added, caustic soda was added to adjust the pH to 7.0, and the mixture was stirred at a rotation speed of 150 rpm for 5 minutes. Then, 1 mg/L of a polymer flocculant (anion colloid equivalent value: 50 meq/g, viscosity of 0.1 wt% aqueous solution: 50 mPa·s (25° C.)), which is an acrylamide/acrylic acid copolymer, was added. After stirring for 1 minute at a rotation speed of 150 rpm, the mixture was stirred at 40 rpm for 5 minutes to grow the floc diameter. After the stirring, the treated water was treated with a quantitative filter paper No. It filtered with 5 A and measured CODMn of the filtrate.

< Reference Example 2-2>
The COD reducing agent C1 is a dimethylamine epichlorohydrin having a viscosity of a 50 wt% aqueous solution of 2,870 mPa·s (25° C.) and a cationic colloid equivalent value of 6.5 meq/g (pH 6). The same treatment as in Reference Example 2-1 was performed except that the ethylene diamine condensate (hereinafter referred to as COD reducing agent C2) was used, and the CODMn of the filtrate of the treated water was measured. The COD reducing agent C2 is a polymer containing the structures represented by the above formulas (1) and (3) and has a weight average molecular weight of about 250,000.

< Reference example 2-3>
Dimethylamine-epichlorohydrin-ethylenediamine condensation of COD reducing agent C1 in which the viscosity of a 50% by weight aqueous solution is 510 mPa·s (25°C) and the cationic colloid equivalent value is 6.5 meq/g (pH 6). The same treatment as in Reference Example 2-1 was performed, except that the product (hereinafter, referred to as COD reducing agent C3) was changed, and the CODMn of the filtrate of the treated water was measured. The COD reducing agent C3 is a polymer containing the structures represented by the above formulas (1) and (3), and has a weight average molecular weight of about 40,000.

<Comparative example 2>
200 mg/L of PAC was added to the wastewater without adding a COD reducing agent, caustic soda was added to adjust the pH to 7.0, and the mixture was stirred at a rotation speed of 150 rpm for 5 minutes. After that, the same treatment as in Reference Example 2-1 was performed, and CODMn of the filtrate of the treated water was measured.

Table 2 shows the measurement results of CODMn of the reference example and the comparative example, the evaluation results of floc formation, floc sedimentation property, and appearance of supernatant water.

As shown in Table 2, the reference example 2-1 containing the COD reducing agent C1 is compared with the reference example 2-2 containing the COD reducing agent C2 and the reference example 2-3 containing the COD reducing agent C3. Then, COD was satisfactorily reduced in Reference Example 2-1. Further, when compared with Comparative Example 2 in which the COD reducing agent was not added, Reference Examples 2-1, 2-2 and 2-3 were better.

As described above, it is clear that the COD reducing agent C1, the COD reducing agent C2, and the COD reducing agent C3 have a COD reducing effect. Further, from the comparison between Reference Example 2-1 and Reference Example 2-2 and Reference Example 2-3, the drug component even dimethylamine epichlorohydrin-ethylene diamine condensate, the viscosity of the 50 wt% aqueous solution It can be seen that there is a difference in the COD reduction effect depending on the difference. Among the dimethylamine/epichlorohydrin/ethylenediamine condensates, the agent having a high COD reducing effect is the COD reducing agent C1 having a property that the viscosity of a 50% by weight aqueous solution is in the range of 800 to 2,000 mPa·s. ..

<Example 3-1>
250 mL of membrane separation activated sludge treated water (solubility CODMn 110 mg/L, SS less than 5 mg/L) of chemical factory wastewater is put in a glass beaker, COD reducing agent A1 is added as solid content of 20 mg/L, and rotation is performed at 150 rpm. Stir at speed for 10 minutes. Next, 1000 mg/L of PAC was added, caustic soda was added to adjust the pH to 7.0, and the mixture was stirred at a rotation speed of 150 rpm for 5 minutes. After that, 2 mg/L of a polymer flocculant (anion colloid equivalent value: 50 meq/g, viscosity of 0.1 wt% aqueous solution: 50 mPa·s), which is an acrylamide/acrylic acid-based copolymer, was added, and rotation was performed at 150 rpm. After stirring at speed for 1 minute, stirring was performed at 40 rpm for 5 minutes to grow the floc diameter. After the stirring, the treated water was treated with a quantitative filter paper No. It filtered with 5 A and measured CODMn of the filtrate.

< Reference Example 3-2>
The COD reducing agent A1 is a polydiallyldimethylammonium chloride having a viscosity of 11,000 mPa·s (25° C.) in a 40% by weight aqueous solution and a cationic colloid equivalent value of 6.2 meq/g (pH 6) (hereinafter, The same treatment as in Example 3-1 was carried out except that the COD reducing agent D was changed to), and the CODMn of the filtrate of the treated water was measured. The COD reducing agent D is a polymer having a structure represented by the above formula (5) and has a weight average molecular weight of about 600,000.

<Comparative example 3>
1000 mg/L of PAC was added to the wastewater without adding the COD reducing agent, caustic soda was added to adjust the pH to 7.0, and the mixture was stirred at a rotation speed of 150 rpm for 5 minutes. After that, the same treatment as in Example 3-1 was performed, and CODMn of the filtrate of the treated water was measured.

Table 3 shows the measurement results of CODMn in Examples and Comparative Examples, the evaluation results of floc formation, floc sedimentation property, and appearance of supernatant water.

As shown in Table 3, comparing Example 3-1 in which the COD reducing agent A1 is added with Reference Example 3-2 in which the COD reducing agent D is added, Example 3-1 shows better COD. Has been reduced. Further, as compared with Comparative Example 3 in which the COD reducing agent was not added, Example 3-1 and Reference Example 3-2 were better.

Since the wastewater used in this test is the membrane permeated water of the membrane separation activated sludge, the wastewater contains almost no SS and the COD component is almost soluble. As can be seen from the measurement result of CODMn in Comparative Example 3, the wastewater has a property that COD can hardly be reduced only by the inorganic coagulant. On the other hand, since CODMn is reduced in Example 3-1 and Reference Example 3-2, COD reducing agent A1 and COD reducing agent D are effective in reducing soluble COD components that are difficult to remove. it is obvious. Further, the COD reducing agent A1 which was a dimethylamine/epichlorohydrin/ammonia condensate was more effective than the COD reducing agent D which was a polydiallyldimethylammonium chloride.

<Example 4-1>
Put 250 mL of humic acid-containing wastewater (solubility CODMn 100 mg/L, SS 5 mg/L or less, chromaticity 1,900 degrees) in a glass beaker, add COD reducing agent A1 as solid content of 20 mg/L, and rotate at 150 rpm. Stir at speed for 10 minutes. Next, 600 mg/L of 35% ferric chloride solution was added, caustic soda was added to adjust the pH to 4.0, and the mixture was stirred at a rotation speed of 150 rpm for 5 minutes. After that, 3 mg/L of a polymer flocculant (anion colloid equivalent value: 50 meq/g, viscosity of 0.1% by weight aqueous solution: 50 mPa·s), which is an acrylamide/acrylic acid-based copolymer, was added and rotated at 150 rpm. After stirring at speed for 1 minute, stirring was performed at 40 rpm for 5 minutes to grow the floc diameter. After the stirring, the treated water was treated with a quantitative filter paper No. After filtering with 5 A, CODMn and chromaticity of the filtrate were measured. The chromaticity was measured using a chromaticity meter (Nippon Denshoku Co., Ltd., Water Analyzer 2000N).

< Reference Example 4-2>
The same treatment as in Example 4-1 was performed except that the COD reducing agent A1 was changed to the COD reducing agent D, and CODMn of the filtrate of the treated water was measured.

<Comparative example 4>
Without adding a COD reducing agent to the waste water, 600 mg/L of 35% ferric chloride solution was added, caustic soda was added to adjust the pH to 4.0, and the mixture was stirred at a rotation speed of 150 rpm for 5 minutes. After that, the same treatment as in Example 4-1 was performed, and the CODMn and chromaticity of the filtrate of the treated water were measured.

Table 4 shows the results of measurement of CODMn and chromaticity, the floc formation, floc sedimentation property, and appearance of supernatant water in Examples and Comparative Examples.

As shown in Table 4, comparing Example 4-1 in which the COD reducing agent A1 was added with Reference Example 4-2 in which the COD reducing agent D was added, Example 4-1 showed better COD. Has been reduced. Further, when comparing the CODMn and the chromaticity of Example 4-1 in which the COD reducing agent A1 was added and Comparative Example 4 in which the COD reducing agent was not added, Example 4-1 was better.

The wastewater used in this test contained a COD component derived from chromaticity. The COD reducing agent A1 is also effective in treating wastewater having such properties, and not only the effect of reducing COD components but also the effect of reducing chromaticity can be expected.

<Example 5-1>
250 mL of treated sludge treated water (solubility CODMn 54 mg/L, SS 5 mg/L or less) of cloth processing wastewater was put into a glass beaker, COD reducing agent A1 was added as solid content of 1 mg/L, and rotation speed was 150 rpm. Stir for minutes. Next, a 40 wt% ferric chloride solution was added at 420 mg/L, caustic soda was added to adjust the pH to 5.0, and the mixture was stirred at a rotation speed of 150 rpm for 5 minutes. After that, 1 mg/L of a polymer flocculant (anion colloid equivalent value: 50 meq/g, viscosity of 0.1 wt% aqueous solution: 50 mPa·s), which is an acrylamide/acrylic acid-based copolymer, was added and rotated at 150 rpm. After stirring at speed for 1 minute, stirring was performed at 40 rpm for 5 minutes to grow the floc diameter. After the stirring, the treated water was treated with a quantitative filter paper No. It filtered with 5 A and measured CODMn of the filtrate. Also, the amount of sludge generated was measured.

<Example 5-2>
2 mg/L of COD reducing agent A1 was added to the waste water as a solid content, and the mixture was stirred at a rotation speed of 150 rpm for 10 minutes. Next, 390 mg/L of 40 wt% ferric chloride solution was added, and caustic soda was added to adjust the pH to 5.0. After that, the same treatment as in Example 5-1 was performed, and CODMn of the filtrate of the treated water and the amount of generated sludge were measured.

<Comparative Example 5>
Without adding a COD reducing agent to the above waste water, 500 mg/L of a 40 wt% ferric chloride solution was added, caustic soda was added to adjust the pH to 5.0, and the mixture was stirred at a rotation speed of 150 rpm for 5 minutes. .. After that, the same treatment as in Example 5-1 was performed, and CODMn of the filtrate of the treated water and the amount of generated sludge were measured.

Table 5 shows the results of measuring CODMn, the amount of sludge, the floc formation, the floc sedimentation property, and the appearance of the supernatant water in Examples and Comparative Examples.

As shown in Table 5, comparing Examples 5-1 and 5-2 to which the COD reducing agent A1 was added and CODMn of Comparative Example 5 to which the COD reducing agent was not added, Examples 5-1 and 5- 2 is better. Moreover, the sludge amount of Examples 5-1 and 5-2 was reduced as compared with Comparative Example 5.

As described above, in Examples 5-1 and 5-2, although the amount of ferric chloride added was smaller than that in Comparative Example 5, the COD was better reduced than in Comparative Example 5. As the amount of ferric chloride added is reduced, the consumption of caustic soda and the amount of sludge generated are also reduced, so that it is possible to keep wastewater treatment costs low. Therefore, it can be said that wastewater treatment using the COD reducing agent A1 can contribute to improvement of treated water quality and reduction of wastewater treatment cost.

<Example 6-1>
250 mL of biofilm-treated water (solubility CODMn 27 mg/L, SS 268 mg/L) of effluent from a dairy manufacturing plant was placed in a glass beaker, and COD reducing agent A1 was added at 8 mg/L as a solid content at a rotation speed of 150 rpm. Stir for 10 minutes. Next, 250 wt/L of a 35 wt% ferric chloride solution was added, caustic soda was added to adjust the pH to 4.0, and the mixture was stirred at a rotation speed of 150 rpm for 5 minutes. After that, 1 mg/L of a polymer flocculant (anion colloid equivalent value: 50 meq/g, viscosity of 0.1% by weight aqueous solution: 50 mPa·s), which is an acrylamide/acrylic acid-based copolymer, was added and rotated at 150 rpm. After stirring at speed for 1 minute, stirring was performed at 40 rpm for 5 minutes to grow the floc diameter. After the stirring, the treated water was treated with a quantitative filter paper No. It filtered with 5 A and measured CODMn of the filtrate.

< Reference Example 6-2>
The same treatment as in Example 6-1 was carried out except that the COD reducing agent A1 was changed to the COD reducing agent D, and CODMn of the filtrate of the treated water was measured.

<Comparative example 6>
Without adding a COD reducing agent to the above waste water, 250 mg/L of 35 wt% ferric chloride solution was added, caustic soda was added to adjust pH to 4.0, and the mixture was stirred at a rotation speed of 150 rpm for 5 minutes. .. After that, the same treatment as in Example 6-1 was performed, and CODMn of the filtrate of the treated water was measured.

Table 6 shows the results of measurement of CODMn in Examples and Comparative Examples, evaluation of floc formation, floc sedimentation, and appearance of supernatant water.

As shown in Table 6, when comparing Example 6-1 to which the COD reducing agent A1 was added and Reference Example 6-2 to which the COD reducing agent D was added, Example 6-1 showed better COD. Has been reduced. Further, when comparing Example 6-1 in which the COD reducing agent A1 is added and CODMn of Comparative Example 6 in which the COD reducing agent is not added, Example 6-1 is better.

Thus, it can be said that the COD reducing agent A1 is also effective in reducing the COD component of low-concentration wastewater such as the soluble CODMn 27 mg/L.

As described above, in the coagulation treatment of the COD-containing water containing the soluble COD component, it was possible to reduce the hardly biodegradable soluble COD component while suppressing the amount of sludge generated.

1,3 Water treatment device, 10 Coagulation device, 12,58 Precipitation tank, 14,54 First reaction tank, 16,56 Second reaction tank, 18 Coagulation tank, 20,76 COD reducing agent addition line, 22,74 Inorganic Flocculant addition line, 24,78 pH adjuster addition line, 26,80 Polymer flocculant addition line, 28,30,32,82,84 Stirrer, 34,60 Treated water inflow line, 36,38,40 , 66,68 water discharge line, 42,70 treated water discharge line, 44,72 sludge discharge line, 50 concentrator, 52 biological treatment device, 62 concentrated water line, 64 biological treated water line.

Claims (8)

A coagulation treatment step of adding a COD reducing agent to COD-containing water containing a soluble COD component to perform coagulation treatment,
The COD reduction agent is a viscosity of 5 0 wt% aqueous solution 1,000 mPa · s or more and the cationic colloidal equivalent value 6.0 meq / g or more (pH 6) Phosphorus dimethylamine epichlorohydrin-a the ammonia condensate seen including,
In the previous stage of the coagulation treatment step, a biological treatment step of biologically treating the water to be treated is included,
The water treatment method , wherein the COD-containing water is biologically treated water obtained in the biological treatment step . The water treatment method according to claim 1, wherein
The solubility CODMn of the COD-containing water is 20 mg/L or more, The water treatment method. The water treatment method according to claim 1 or 2 , wherein
Before the biological treatment step,
Including a concentration step of concentrating organic matter-containing water containing organic matter,
In the biological treatment step, the water treatment method comprising a benzalkonium be biologically treated a concentrate obtained in the concentration step. The water treatment method according to any one of claims 1 to 3 ,
In the biological treatment step, a biological treatment is carried out by a membrane separation activated sludge method. A COD-containing water containing a soluble COD component is added with a COD reducing agent to provide a coagulation treatment means,
The COD reduction agent is a viscosity of 5 0 wt% aqueous solution 1,000 mPa · s or more and the cationic colloidal equivalent value 6.0 meq / g or more (pH 6) Phosphorus dimethylamine epichlorohydrin-a the ammonia condensate seen including,
The biological treatment means for biologically treating the water to be treated is provided in the preceding stage of the aggregation treatment means,
The COD-containing water is biologically treated water obtained by the biological treatment means . The water treatment device according to claim 5 ,
The solubility CODMn of the COD-containing water is 20 mg/L or more. The water treatment device according to claim 5 or 6 , wherein
In front of the biological treatment means,
Equipped with a concentration means for concentrating organic matter-containing water containing organic matter,
The biological treatment means, the water treatment apparatus, characterized in that the concentrate obtained by the concentration means is to biological treatment. The water treatment device according to any one of claims 5 to 7 ,
The water treatment device, wherein the biological treatment means performs biological treatment by a membrane separation activated sludge method.

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