JP2009154095A - Water treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water treatment method which can efficiently remove a soluble COD component such as a nonionic soluble COD component even without performing activated carbon treatment causing the problem of a clogging trouble or the like, water passing to an ion exchange resin column, membrane treatment or the like. <P>SOLUTION: Regarding the water treatment method, an anionic polymer electrolyte with the weight average molecular weight of ≥1,000 is added to the water to be treated, thereafter, a cationic polymer electrolyte with the weight average molecular weight of 10,000 to 1,000,000 is added thereto, and stirring is performed, or, the cationic polymer electrolyte is added simultaneously with the anionic polymer electrolyte, and stirring is performed, and thereafter, an inorganic flocculant and an organic flocculant are successively added. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for treating water such as wastewater. More specifically, the present invention relates to industrial wastewater discharged from printing factories, semiconductor factories, food factories, paper / pulp factories, chemical factories, etc., treatment from human waste treatment plants, and sewage treatment plants. The present invention relates to a water treatment method capable of efficiently removing soluble COD components contained in water or purified water or water.

  From the viewpoint of protecting the global environment and ensuring human health, regulations relating to wastewater treatment are becoming stricter on a global scale year by year. In particular, with regard to discharge into rivers and closed water areas, movements in the national and local governments have become active, such as reviewing regulatory values for water quality management items. Substances subject to water quality regulations include not only toxic and harmful substances, but also phosphorus, nitrogen, BOD, COD (chemical oxygen demand) and other chemical substances that cause eutrophication in lakes and marine areas. COD as an index of pollution is a particularly important regulatory management item.

  Conventionally, biological treatment such as an activated sludge method, coagulation sedimentation treatment, and pressurized flotation treatment are generally used as treatment of soluble COD components contained in factory wastewater and the like. However, in the case of biological treatment, there is a problem that a large area is required for the treatment apparatus, and therefore, there are many cases where treatment is performed by coagulation sedimentation treatment or pressure flotation treatment. And the coagulation sedimentation treatment and the pressure flotation treatment are methods for removing suspended substances and anionic soluble COD components that are mainly negatively charged due to the charge neutralization action of the inorganic flocculant. It is basically difficult to remove nonionic soluble COD components such as nonionic surfactants which are problematic in many industrial wastewaters such as semiconductor factories, food factories, paper / pulp factories, chemical factories, and the like.

  Physiological chemistry such as activated carbon treatment, ultraviolet irradiation, ozone treatment, Fenton treatment combining ferrous sulfate and hydrogen peroxide can be used to remove soluble COD components from water, including this nonionic soluble COD component. Method (see Non-Patent Document 1), a method of passing a liquid to be treated through an ion exchange resin column, a method of performing a membrane treatment (see Patent Document 1 and Patent Document 2), and itself easily increases flocs by increasing cohesion A method of stably and efficiently performing wastewater treatment by adding a weighting agent such as a hydrophilic clay mineral to the wastewater and then coagulating and precipitating is disclosed (see Patent Document 3).

  However, physicochemical methods such as activated carbon treatment, ultraviolet irradiation, ozone treatment, and Fenton treatment combining ferrous sulfate and hydrogen peroxide can block activated carbon adsorption towers, reduce ultraviolet irradiation efficiency, and consume ozone and chemicals. There is a problem that it is easy to invite. There is also a problem that drug costs and electricity costs increase. In the method of passing the liquid to be treated through the ion exchange resin column or the method of membrane treatment, if suspended substances are included, clogging easily occurs, so additional pretreatment equipment such as filtration and sedimentation separation is required. There is a problem of becoming. Furthermore, the method of coagulating and precipitating after adding a weighting agent such as a hydrophilic clay mineral has the problem that the treatment efficiency is low, although the clay mineral has the advantage that the chemical itself is inexpensive. Moreover, the problem that the amount of sludge will increase also arises.

JP 2000-317445 A JP 2001-276825 A JP 2003-245504 A Nobuyuki Yamamoto, Accelerated Oxidation, Chemical Industry, Vol. 30, No. 9, 335-338 (2002)

  In view of the above-described circumstances, the present invention eliminates soluble COD components such as nonionic soluble COD components without performing activated carbon treatment that causes problems such as clogging troubles, water passing through ion exchange resin columns, membrane treatment, and the like. It aims at providing the water treatment method which can be removed efficiently.

  As a result of intensive studies to achieve the above object, the present inventor added a cationic polymer electrolyte having a weight average molecular weight of 10,000 or more and 1,000,000 or less after adding an anionic polymer electrolyte having a weight average molecular weight of 1,000 or more. Or by adding the cationic polymer electrolyte simultaneously with the anionic polymer electrolyte and stirring, and then adding the inorganic flocculant and the organic polymer flocculant in order. The present invention has been completed.

  That is, in the water treatment method of the present invention, an anionic polymer electrolyte having a weight average molecular weight of 1000 or more is added to water to be treated, and then a cationic polymer electrolyte having a weight average molecular weight of 10,000 to 1,000,000 is added. The cationic polymer electrolyte is added and stirred simultaneously with the anionic polymer electrolyte, and then an inorganic flocculant and an organic polymer flocculant are added in order.

  Moreover, when the said to-be-processed water contains a nonionic soluble COD component, the effect of this invention can be exhibited notably especially.

  After adding an anionic polymer electrolyte having a weight average molecular weight of 1000 or more to the water to be treated, a cationic polymer electrolyte having a weight average molecular weight of 10,000 to 1,000,000 is added and stirred, or the anionic Activated carbon treatment and ion exchange resin that causes problems such as clogging troubles by adding the cationic polymer electrolyte simultaneously with the polymer electrolyte and stirring, and then sequentially adding the inorganic flocculant and the organic polymer flocculant There is an effect that soluble COD components such as nonionic soluble COD components can be efficiently removed from water to be treated such as factory effluent without water passing through the column or membrane treatment.

  Hereinafter, the present invention will be described in detail based on embodiments.

  In the water treatment method of the present invention, after adding an anionic polymer electrolyte having a weight average molecular weight of 1000 or more, a cationic polymer electrolyte having a weight average molecular weight of 10,000 to 1,000,000 is added and stirred, or The cationic polymer electrolyte is added simultaneously with the anionic polymer electrolyte and stirred, and then an inorganic flocculant and an organic polymer flocculant are sequentially added.

  Examples of treated water include industrial wastewater discharged from printing factories, semiconductor factories, food factories, paper / pulp factories, chemical factories, treated water from human waste treatment plants, sewage treatment plants, or purified water and water for use. . Such treated water usually has anionic, cationic or nonionic solubility such as saccharides and proteins derived from natural sources, surfactants, derived from industrial raw materials and chemicals, derived from foods, and their degradation products. Contains a COD component. According to the water treatment method of the present invention, the soluble COD component contained in the water to be treated, particularly the nonionic soluble COD component that has been difficult to remove, can be efficiently removed.

  In the present invention, first, an anionic polymer electrolyte having a weight average molecular weight of 1000 or more is added to such water to be treated, and then a cationic polymer electrolyte having a weight average molecular weight of 10,000 to 1,000,000 is added. Stirring is performed, or a cationic polymer electrolyte having a weight average molecular weight of 10,000 to 1,000,000 is added and stirred simultaneously with the anionic polymer electrolyte having a weight average molecular weight of 1,000 or more. When the latter anionic polymer electrolyte having a weight average molecular weight of 1000 or more and a cationic polymer electrolyte having a weight average molecular weight of 10,000 to 1,000,000 are simultaneously added to the water to be treated, the weight average molecular weight is 1,000 or more. The anionic polymer electrolyte and the cationic polymer electrolyte having a weight average molecular weight of 10,000 to 1,000,000 may be separately added to the water to be treated, and the anionic polymer electrolyte having a weight average molecular weight of 1,000 or more. A solution in which a molecular electrolyte and a cationic polymer electrolyte having a weight average molecular weight of 10,000 to 1,000,000 are dissolved may be prepared, and the solution may be added to water to be treated.

  Thus, after adding an anionic polymer electrolyte having a weight average molecular weight of 1000 or more to the water to be treated, a cationic polymer electrolyte having a weight average molecular weight of 10,000 to 1,000,000 is added and stirred, or A polyion complex that is a reaction product between polymers by adding and stirring the cationic polymer electrolyte simultaneously with the anionic polymer electrolyte and reacting the anionic polymer electrolyte with the cationic polymer electrolyte Precipitates. As a result of this precipitation, suspended substances, organic substances, and COD components contained in the water to be treated also precipitate at the same time, so that the amount of soluble COD components such as nonionic COD components dissolved in the liquid to be treated can be reduced. The agglomeration reaction by adding the inorganic flocculant and the organic polymer flocculant can be performed efficiently. Therefore, soluble COD components and suspended substances can be easily removed from the system.

  When a cationic polymer electrolyte having a weight average molecular weight of 10,000 to 1,000,000 is added to the water to be treated prior to the anionic polymer electrolyte having a weight average molecular weight of 1,000 or more, the cationic polymer electrolyte is First, it reacts with the suspended solids contained in the water to be treated, and even if an anionic polymer flocculant is added thereafter, it becomes difficult to produce a reaction product between the cationic polymer electrolyte and the anionic polymer electrolyte. Therefore, the removal effect of the soluble COD component of the present invention cannot be obtained.

  Even if an anionic polymer electrolyte having a weight average molecular weight of less than 1000 or a cationic polymer electrolyte having a weight average molecular weight of more than 1,000,000 is used, the effect of removing the soluble COD component of the present invention cannot be obtained.

  The anionic polymer electrolyte having a weight average molecular weight of 1000 or more added to the water to be treated can be copolymerized with a polymer or copolymer obtained by polymerizing a monomer having an anionic functional group, or a monomer having an anionic functional group. Examples thereof include a copolymer with a nonionic monomer. The monomer having an anionic functional group is not particularly limited, and examples thereof include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, maleic acid, and itaconic acid, vinyl sulfonic acid, allyl sulfonic acid, and 2-acrylamido-2-methylpropane. Examples thereof include sulfonic acid group-containing monomers such as sulfonic acid. Nonionic monomers include, but are not limited to, acrylamide, methacrylamide, acrylonitrile, methyl (meth) acrylate, ethyl (meth) acrylate, styrene, and the like.

  Further, as described above, the weight average molecular weight of the anionic polymer electrolyte added to the water to be treated may be 1000 or more, but preferably 1 million or less. In an anionic polymer electrolyte having a weight average molecular weight of less than 1000, a solid polyion complex is not generated, and the polymer itself becomes a COD component. On the other hand, if the weight average molecular weight is larger than 1,000,000, the polyion complex may be in the form of gel or rubber, which may hinder the aggregation treatment. In order to disperse uniformly in the water to be treated, the weight average molecular weight of the anionic polymer electrolyte is preferably 2000 to 500,000, more preferably 100,000 or less. The weight average molecular weight of the anionic polymer electrolyte can be measured by a gel permeation chromatography method (hereinafter referred to as GPC method).

  Moreover, the addition amount of the anionic polymer electrolyte having a weight average molecular weight of 1000 or more is 1 mg / L or more with respect to the water to be treated. This is because if it is less than 1 mg / L, the removal effect of the soluble COD component of the present invention is not significant.

  The cationic polymer electrolyte having a weight average molecular weight of 10,000 to 1,000,000 added to the water to be treated includes a polymer or copolymer obtained by polymerizing a monomer having a cationic functional group, a monomer having a cationic functional group, Examples thereof include a copolymer with a copolymerizable nonionic monomer. Examples of the monomer having a cationic functional group include dimethylaminoethyl (meth) acrylate and a quaternized product thereof, dimethylaminopropyl (meth) acrylamide and a quaternized product thereof, diallyldimethylammonium chloride, and allylamine. Nonionic monomers include, but are not limited to, acrylamide, methacrylamide, acrylonitrile, methyl (meth) acrylate, ethyl (meth) acrylate, styrene, and the like. The cationic polyelectrolyte may be a polymer cationized by a polymer reaction, for example, polyamine-N-vinylformamide or polyamine-N-vinylacetamide by hydrolysis, polyvinylamine, N-vinylformamide and acrylonitrile. And amidine-based polymers obtained by modification of the copolymer. Furthermore, the cationic polymer electrolyte may be polyethyleneimine, ethylenediamine epichlorohydrin polycondensate, polyalkylene polyamine, or dimethylamine-epichlorohydrin condensate.

  Further, as described above, the cationic polymer electrolyte added to the water to be treated has a weight average molecular weight of 10,000 to 1,000,000. This is because the anionic polymer electrolyte and the cationic polymer electrolyte to be added first or at the same time are not a rubber-like lump precipitate but a uniform precipitate in the water to be treated. The weight average molecular weight of the cationic polymer electrolyte can be measured by a light scattering method. Moreover, you may measure the weight average molecular weight of a cationic polymer electrolyte by the method calculated | required from intrinsic viscosity. For example, when the weight average molecular weight of 10,000 or more and 1,000,000 or less of the cationic polymer electrolyte added to the water to be treated in the present invention is converted into an intrinsic viscosity at 30 ° C. in 1N-NaCl, it is 0.00 at 1 dL / g or less. It is 03 dL / g or more.

  Moreover, the addition amount of the cationic polymer electrolyte having a weight average molecular weight of 10,000 to 1,000,000 is 1 mg / L or more with respect to the water to be treated. This is because the effect of the present invention is not remarkable if it is less than 1 mg / L.

  The ratio of the addition amount of the anionic polymer electrolyte having a weight average molecular weight of 1,000 or more and the cationic polymer electrolyte having a weight average molecular weight of 10,000 to 1,000,000 is anionic polymer electrolyte: cationic polymer electrolyte = 70: 30. It is preferably ˜30: 70 (mass ratio). If it is outside this range, either the anionic polymer electrolyte or the cationic polymer electrolyte remains in the water to be treated, so that an electrically uniform reaction product cannot be formed, and the soluble COD component of the present invention is removed. This is because the effect is not noticeable.

  In addition, there is no particular limitation on the form of adding the anionic polymer electrolyte or the cationic polymer electrolyte to the water to be treated, an operation method of an aqueous solution of the anionic polymer electrolyte or the cationic polymer electrolyte in a normal water treatment, For example, a certain amount may be added according to the amount of treated water using a liquid feed pump.

  Thus, after adding an anionic polymer electrolyte having a weight average molecular weight of 1,000 or more to the water to be treated, a cationic polymer electrolyte having a weight average molecular weight of 10,000 to 1,000,000 is added and stirred, or The cationic polymer electrolyte is added at the same time as the anionic polymer electrolyte and stirred, then an inorganic flocculant is added, and then an organic polymer flocculant is added, so that a nonionic soluble COD component, etc. The soluble COD component can be easily removed from the water to be treated.

  There is no limitation in particular in the inorganic flocculant added to to-be-processed water, For example, a sulfuric acid band, polyaluminum chloride, ferric chloride, ferrous sulfate etc. are mentioned. Further, the amount of the inorganic flocculant added is not particularly limited and may be adjusted according to the properties of the water to be treated.

  The organic polymer flocculant is not particularly limited, and organic polymer flocculants usually used in water treatment can be used. For example, poly (meth) acrylic acid, copolymers of (meth) acrylic acid and (meth) acrylamide, and anionic organic polymer flocculants such as alkali metal salts thereof, nonions such as poly (meth) acrylamide Organic polymer flocculants, homopolymers composed of cationic monomers such as dimethylaminoethyl (meth) acrylate or quaternary ammonium salts thereof, dimethylaminopropyl (meth) acrylamide or quaternary ammonium salts thereof, and their cationic properties Examples thereof include cationic organic polymer flocculants such as a copolymer of a nonionic monomer copolymerizable with a monomer. The amount of the organic polymer flocculant added is not particularly limited, and may be adjusted according to the properties of the water to be treated.

  An organic coagulant can also be used in combination. The organic coagulant is not particularly limited, and examples thereof include cationic organic polymers that are usually used in water treatment, such as polyethyleneimine, diallyldimethylammonium chloride, ethylenediamine epichlorohydrin polycondensate, and polyalkylene polyamine. Moreover, there is no limitation in particular also in the addition amount of an organic coagulant | flocculant, What is necessary is just to adjust according to the property of to-be-processed water, but it is 1-100 mg / L in solid content with respect to to-be-processed water. The addition timing of the organic coagulant is not particularly limited.

  Although there is no restriction | limiting in particular in the pH at the time of the aggregation process by addition of an inorganic flocculant or an organic polymer flocculant, The neutral range which is easy to perform an aggregation process, and the range of normal pH 5-9 are preferable. For example, after adding an inorganic flocculant and an organic flocculant to be added as necessary, the pH may be adjusted to 5 to 9 before adding the organic polymer flocculant. The method for adjusting the pH is not particularly limited. For example, an acidic substance such as sulfuric acid, hydrochloric acid, or nitric acid, or an alkaline substance such as sodium hydroxide may be added.

After adding an inorganic flocculant, add an organic polymer flocculant and react by stirring to agglomerate soluble COD components such as suspended matter and nonionic soluble COD components. By separating and removing the agglomerated floc that has been separated by gravity sedimentation, pressurized flotation, filtration, etc., the soluble COD component can be removed from the water to be treated. The effect of removing the soluble COD component can be confirmed by measuring the COD _Mn and COD _Cr by filtering the treated water obtained by treating with the water treatment method of the present invention as necessary.

  Moreover, you may add a disinfectant, a deodorant, an antifoamer, an anticorrosive, etc. as needed. Furthermore, if necessary, ultraviolet irradiation, ozone treatment, membrane treatment, biological treatment, etc. may be used in combination.

  EXAMPLES Hereinafter, although this invention is explained in full detail based on an Example and a comparative example, this invention is not limited at all by this Example.

Example 1
Prepare a 500 mL beaker containing 500 mL of total wastewater discharged from the pulp and paper mill (containing nonionic soluble COD components, SS (turbidity) concentration 3250 mg / L, raw water COD _Mn = 415 mg / L), and jar tester Installed. And after adding the anionic polymer electrolyte A1-1 shown in following Table 1 to the beaker with the addition rate 2 mg / L with respect to waste_water | drain, it stirred at 150 rpm for 120 second. Subsequently, the cationic polymer electrolyte C1-1 shown in Table 1 below was added at a rate of 2 mg / L with respect to the waste water, and then stirred at 150 rpm for 120 seconds. Next, an inorganic flocculant (18 wt% sulfuric acid band with Al ₂ O ₃ ) was added to the beaker at 250 mg / L with respect to the waste water, stirred at 150 rpm for 60 seconds, and adjusted to pH 6.5 with 5% NaOH. Adjust and stir at 150 rpm for 60 seconds. Subsequently, an organic polymer flocculant (a copolymer of sodium acrylate: acrylamide = 20: 80 (mol%), 1N-NaCl, intrinsic viscosity dL / g = 22 measured at 30 ° C.) was discharged into the beaker with respect to the wastewater. 2 mg / L was added, and the mixture was first stirred at 150 rpm for 60 seconds and then at 50 rpm for 180 seconds to aggregate SS (turbidity). After the stirring was stopped, the turbidity (NTU) of the supernatant of each beaker was measured. The filtrate was filtered with 5A filter paper (manufactured by Advantech Co., Ltd., retained particle diameter 7 μm), and COD _Mn of the filtrate was measured. The measurement results are shown in Table 2.

(Example 2)
The same operation as in Example 1 was performed except that the anionic polymer electrolyte and the cationic polymer electrolyte were separately added to the waste water simultaneously. The results are shown in Table 2.

(Examples 3 to 5)
The same operation as in Example 1 was performed except that the types of anionic polymer electrolyte and cationic polymer electrolyte were as shown in Table 2 below. The results are shown in Table 2.

(Example 6)
The same operation as in Example 2 was performed except that the types and addition rates of the anionic polymer electrolyte and the cationic polymer electrolyte were as shown in Table 2 below. The results are shown in Table 2.

(Comparative Example 1)
The same operation as that after the addition of the inorganic flocculant in Example 1 was performed without adding the anionic polymer electrolyte and the cationic polymer electrolyte. The results are shown in Table 2.

(Comparative Example 2)
The same operation as in Example 1 was performed except that the cationic polymer electrolyte was added before the anionic polymer electrolyte. The results are shown in Table 2.

(Comparative Examples 3-6)
The same operation as in Example 1 was performed except that the types of anionic polymer electrolyte and cationic polymer electrolyte were as shown in Table 2 below. The results are shown in Table 2.

(Comparative Examples 7 and 8)
The kind and addition amount of the anionic polymer electrolyte and the cationic polymer electrolyte are as shown in Table 2, and the same as in Example 1 except that the anionic polymer electrolyte and the cationic polymer electrolyte were separately added to the waste water simultaneously. Was performed. The results are shown in Table 2.

As shown in Table 2, in Examples 1 to 6 treated with the water treatment method of the present invention, good results were obtained for both the treated water turbidity and COD _Mn, and the turbidity and COD _Mn components were removed. Was confirmed. On the other hand, outside the scope of the present invention, specifically, Comparative Example 1 in which the anionic polymer electrolyte and the cationic polymer electrolyte were not added, the cationic polymer electrolyte was added before the anionic polymer electrolyte. Comparative Example 2, Comparative Example 3, Comparative Example 4 and Comparative Example 8 to which an anionic polymer electrolyte having a weight average molecular weight of less than 1000 was added, Comparative Example 5 to which a cationic polymer electrolyte having a weight average molecular weight of more than 1,000,000 was added In -7, turbidity and COD _Mn component could not be removed.

Claims (2)

  After adding an anionic polymer electrolyte having a weight average molecular weight of 1000 or more to the water to be treated, a cationic polymer electrolyte having a weight average molecular weight of 10,000 to 1,000,000 is added and stirred, or the anionic A water treatment method comprising adding the cationic polymer electrolyte together with the polymer electrolyte and stirring the mixture, and then sequentially adding an inorganic flocculant and an organic polymer flocculant.   The water treatment method according to claim 1, wherein the water to be treated contains a nonionic soluble COD component.