JP2008246372A - Waste water treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waste water treatment method by which suspended solids and dissoluble COD (chemical oxygen demand) contained in waste water discharged from public waste water sludge treatment facilities such as a sewage treatment plant and a night soil treatment plant and industrial waste water discharged from general plants such printing plants, chemical plants, semiconductor plants, food plants and paper-pulp plants can be efficiently removed. <P>SOLUTION: The waste water treatment method is provided for adding the particulates of a cationic or nonionic polymer swelling in water and not substantially dissolved in water to water water, and after flocculation reaction, performing solid-liquid separation, wherein the liquid containing the polymer particulates is treated by a homogenizer for ≥30 s, and is added to the waste water. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a wastewater treatment method. More specifically, the present invention relates to wastewater discharged from public wastewater sludge treatment facilities such as sewage treatment plants and human waste treatment plants, and general factories such as printing factories, chemical factories, semiconductor factories, food factories, and paper and pulp factories. The present invention relates to a wastewater treatment method that can efficiently remove suspended substances and soluble COD components contained in factory wastewater discharged from the factory.

  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, regarding river discharge and discharge into closed water areas, movements in the national and local governments have become active, such as reviewing the regulatory values for water quality management items. Substances subject to water quality regulations include, in addition to toxic and harmful substances, phosphorus, nitrogen and BOD components that cause eutrophication in lakes and marine areas. COD, which is an indicator of chemical pollution, It is an important regulatory management item.

  Conventionally, biological treatment such as an activated sludge method, coagulation sedimentation treatment, and pressurized flotation treatment are generally used as a technique for treating a soluble COD component contained in factory effluent. However, in the case of biological treatment, since a large area is required for the treatment apparatus, the treatment is often performed by coagulation sedimentation or pressurized flotation. The coagulation-precipitation treatment and the pressure levitation treatment are methods that mainly remove negative suspended substances and anionic soluble COD components by charge neutralization of inorganic coagulants. It is difficult to remove a nonionic-based soluble COD component such as a nonionic surfactant, which is a problem in many industrial wastewaters such as factories, food factories, and paper / pulp factories.

  As a technique for removing soluble COD components from water, including nonionic properties that are difficult to treat, the following methods have been generally employed. However, each method still has problems to be solved.

(1) Physicochemical methods such as activated carbon treatment, ultraviolet irradiation, ozone treatment, Fenton treatment combining ferrous sulfate and hydrogen peroxide (Non-patent Document 1). These physicochemical methods cannot be said to be widespread due to increased drug costs and electricity costs. In particular, when suspended substances coexist, the influence is great, and the activated carbon adsorption tower is blocked, the ultraviolet irradiation efficiency is lowered, and ozone and chemicals are easily consumed.

(2) A method in which an organic substance contained in a liquid to be treated is irradiated with ultraviolet rays to decompose it into an organic acid, and then passed through an ion exchange resin column (Patent Document 1). When the wastewater contains suspended substances, the efficiency of ultraviolet irradiation decreases and the ion exchange resin column is easily clogged. Therefore, pretreatment facilities such as filtration and sedimentation separation are separately required, and there is a problem in terms of capital investment.

(3) A method of performing a film treatment (Patent Document 2). If the drainage contains suspended matter, it will easily clog the membrane device. Pretreatment facilities such as filtration and sedimentation separation are necessary, and there are also problems in terms of capital investment.

(4) A method of stably and efficiently performing a wastewater treatment for coagulating sedimentation after adding a weighting agent such as a hydrophilic clay mineral that enhances cohesiveness and easily generates flocs to the wastewater (Patent Document 3) ). Although the clay mineral has the advantage that the chemical itself is low in price, the treatment efficiency is low, the amount of sludge increases, and the treatment cost increases.

(5) A method for treating starch-containing water, wherein cationic polymer fine particles that swell in water and do not substantially dissolve in water are added to water (Patent Document 4). Since the polymer fine particles are swollen in water, they are greatly influenced by water quality such as polymerization conditions and coexisting ions, and the particle diameter and surface area of the swollen fine particles are not constant, so that the aggregation effect is not stable.

Nobuyuki Yamamoto, Accelerated Oxidation Process, Chemical Industry, Vol. 30, No. 9, 335-338 (2002) JP 2000-317445 A JP 2001-276825 A JP 2003-245504 A Japanese Patent Publication No. 7-83869

  The present invention is discharged from public wastewater sludge treatment facilities such as sewage treatment plants and human waste treatment plants, and from general factories such as printing factories, chemical factories, semiconductor factories, food factories, and paper and pulp factories. The object of the present invention is to provide a wastewater treatment method capable of efficiently removing suspended substances and soluble COD components contained in factory wastewater.

As a result of intensive research to solve the above-mentioned problems, the present inventors have added cationic or nonionic polymer fine particles that swell in water and do not substantially dissolve in water to the wastewater, agglomeration treatment, solid liquid In the wastewater treatment method to be separated, the liquid containing the polymer fine particles is treated with a homogenizer for 30 seconds or more and added to the wastewater, whereby the floc diameter obtained by the coagulation treatment is increased, and the turbidity of the supernatant is increased. It has been found that COD _Mn decreases, and the present invention has been completed based on this finding.

That is, the present invention
(1) In a wastewater treatment method in which cationic or nonionic polymer fine particles that swell in water and do not substantially dissolve in water are added to wastewater, and after agglomeration reaction, solid-liquid separation is performed. A wastewater treatment method characterized in that the treatment is performed for 30 seconds or more and added to wastewater;
(2) The wastewater treatment method according to (1), wherein the polymer fine particles that swell in water and do not substantially dissolve in water are cationic polymer fine particles, and
(3) The wastewater treatment method according to (2), wherein the cationic polymer fine particle is a polymer comprising a bifunctional monomer as a cross-linking agent and one or more monomers including a quaternary ammonium salt monomer.
Is to provide.

  By the wastewater treatment method of the present invention, wastewater discharged from public wastewater sludge treatment facilities such as sewage treatment plants and human waste treatment plants, and discharged from chemical factories, printing factories, semiconductor factories, food factories, paper and pulp factories, etc. If the factory wastewater is treated, suspended substances and soluble COD components contained in the wastewater can be stably and efficiently removed. In addition, by applying the method of the present invention to wastewater treatment using inorganic flocculants, the amount of inorganic flocculants used is reduced, the amount of sludge that is industrial waste is reduced, and disposal costs are reduced and the global environment is protected. It can contribute greatly.

  In the wastewater treatment method of the present invention, in the wastewater treatment method in which cationic or nonionic polymer fine particles that swell in water and do not substantially dissolve in water are added to the wastewater, agglomeration treatment is performed, and solid-liquid separation is performed. The liquid containing is treated with a homogenizer for 30 seconds or more and added to the waste water. The method of the present invention includes wastewater discharged from public wastewater sludge treatment facilities such as sewage treatment plants and human waste treatment plants, and factory wastewater discharged from chemical factories, printing factories, semiconductor factories, food factories, paper and pulp factories, etc. For example, suspended substances and soluble COD components contained in waste water can be stably and efficiently removed.

  Examples of the cationic polymer that is substantially insoluble in water used in the method of the present invention include a copolymer of a cationic monomer such as amine or quaternary ammonium salt and a polyfunctional monomer, N-vinylformamide, acrylonitrile, and many. Examples thereof include a polymer having an amidine structure by hydrolysis and a cyclization reaction of a copolymer of a functional monomer, and chitosan. Among these, a copolymer of a cationic monomer such as a primary amine, secondary amine, tertiary amine, a salt thereof, or a quaternary ammonium salt and a polyfunctional monomer can be preferably used. Examples of the cationic monomer include dimethylaminoethyl (meth) acrylate acid salt or quaternary ammonium salt, dimethylaminopropyl (meth) acrylamide acid salt or quaternary ammonium salt, diallyldimethylammonium chloride, and the like. Can do. Examples of the polyfunctional monomer used for making the polymer into fine particles that are substantially insoluble in water include divinyl monomers such as methylenebisacrylamide.

  In the method of the present invention, a copolymer with a copolymerizable monomer can also be used as the cationic polymer fine particles. Examples of the copolymerizable monomer include anionic monomers such as (meth) acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, and alkali metal salts thereof, (meth) acrylamide, N-isopropylacrylamide, and dimethylacrylamide. And nonionic monomers such as acrylonitrile, styrene, methyl (meth) acrylate, and ethyl (meth) acrylate.

  Nonionic polymers that are substantially insoluble in water used in the method of the present invention include, for example, (meth) acrylamide, N-isopropylacrylamide, dimethylacrylamide, acrylonitrile, styrene, methyl (meth) acrylate, ethyl (meth) acrylate, heavy Examples thereof include polymers such as (meth) acrylates, allyl ethers and vinyl ethers having a polyoxyethylene unit having a degree of coalescence of about 2 to 20. As with the cationic polymer fine particles, it is preferable to copolymerize a divinyl monomer such as methylenebisacrylamide as a cross-linking agent in order to obtain fine particles that are substantially insoluble in water.

  Examples of the liquid containing cationic or nonionic polymer fine particles that swell in water and do not substantially dissolve in water include a reversed-phase emulsion liquid and a suspension-like dispersion liquid. As a reverse phase (W / O) emulsion polymer liquid, for example, a cationic polymer having a crosslinked structure, water, a hydrocarbon liquid, and a surfactant in a weight ratio of 20 to 40:20 to 40:20 to 40: 2 to 20 And a liquid in which the total amount of the cationic polymer having a crosslinked structure and water is 40 to 60% by weight based on the total weight. The amount of the polyfunctional monomer such as methylene bisacrylamide to be copolymerized as an emulsion as the cross-linking agent is preferably 0.0001 to 0.1 mol% with respect to the total monomer, and this amount determines the degree of swelling of the polymer fine particles. That is, the particle diameter in water can be adjusted.

  Examples of the hydrocarbon liquid used for the reversed phase emulsion liquid include isoparaffins such as isohexane, aliphatic hydrocarbon liquids such as n-hexane, kerosene, and mineral oil. Examples of the surfactant include polyoxyethylene ethers of higher aliphatic (C10-20) alcohols having an HLB of 7 to 10, polyoxyethylene esters of higher fatty acids (C10 to 22), and the like. Examples of the polyoxyethylene ether of higher alcohol include polyoxyethylene (3 to 10 mol) ethers such as lauryl alcohol, cetyl alcohol, stearyl alcohol, and oleyl alcohol. Examples of higher fatty acid polyoxyethylene esters include polyoxyethylene (3 to 10 mol) esters such as lauric acid, palmitic acid, stearic acid, and oleic acid.

  In the method of the present invention, the particle diameter of the unswelled fine particles in the reversed-phase emulsion liquid or the suspension-like dispersion liquid is preferably 100 μm or less, more preferably 0.1 to 10 μm. In the method of the present invention, when water-insoluble polymer fine particles that swell in water are added to waste water, a stirring treatment is performed to swell the fine particles in order to increase the surface area of the fine particles. The average particle diameter of the swollen fine particles is preferably 10 to 200 μm, and more preferably 10 to 50 μm. The particle diameter of the fine particles can be measured using a commercially available particle size distribution meter.

  In the method of the present invention, a liquid containing polymer fine particles is treated with a homogenizer for 30 seconds or more. Examples of the homogenizer include a high-speed homogenizer, an ultrasonic homogenizer, a high-pressure homogenizer, and the like. Preferably, it is a throwing type or a line mixer type. The liquid to be treated with the homogenizer may be a stock solution of a polymer product liquid, or an aqueous dispersion diluted with water to a polymer fine particle concentration of 0.1 to 10% by weight. The processing time by the homogenizer is 30 seconds or more, and more preferably 30 seconds to 15 minutes. If the processing time is less than 30 seconds, the processing effect may not be obtained. If the processing time exceeds 15 minutes, work efficiency may be reduced. When a high-speed homogenizer is used, the rotation speed of the homogenizer is usually preferably 3,000 rpm or more, more preferably 4,000 rpm or more, and further preferably 5,000 rpm or more. If the rotational speed of the homogenizer is less than 3,000 rpm, the shearing force applied to the liquid containing the polymer fine particles is insufficient, and the stirring effect may not be obtained.

  In the method of the present invention, there is no particular limitation on the method of adding the liquid containing polymer fine particles treated with the homogenizer to the waste water, and the polymer product stock solution can be added as it is, or it can be diluted and added. . It is better to dilute and add the polymer stock solution because it has better dispersibility of fine particles in wastewater, works efficiently, has better effect, and has better handleability. Is preferred. The dilution of the polymer product stock solution can be performed either before or after the treatment with the homogenizer. The diluted liquid preferably has a polymer fine particle concentration of 0.1 to 10% by weight.

  Examples of wastewater to be treated by the method of the present invention include, for example, industrial wastewater discharged from printing factories, semiconductor factories, food factories, paper / pulp factories, chemical factories, treatment from human waste treatment plants, and sewage treatment plants. Water, purified water and irrigation water can be mentioned. By applying the method of the present invention, the soluble COD component contained therein can be removed particularly efficiently. Soluble COD components range from natural sources such as saccharides and proteins, surfactants and industrial materials and chemicals, foods, and their degradation products, but the method of the present invention is particularly limited. It can be effectively processed for any of them. There is no limitation on the ionicity of the soluble COD component such as anionic property, cationic property, and nonionic property, and any of these can be effectively treated.

  In the wastewater treatment method of the present invention, there are no particular limitations on the methods of the agglomeration treatment and the solid-liquid separation treatment, and examples thereof include an agglomeration precipitation treatment and a pressurized flotation treatment. After adding an inorganic flocculant to the wastewater to be treated, adjust the pH using sodium hydroxide, calcium hydroxide, sulfuric acid, etc., and finally flocculate the suspension using an organic polymer flocculant. be able to. Moreover, an organic coagulant can also be used together as needed. For the addition of the liquid containing polymer fine particles stirred by a homogenizer, any of before the addition of the inorganic flocculant, before the pH adjustment after the addition of the inorganic flocculant, and after the pH adjustment after the addition of the inorganic flocculant should be arbitrarily selected. Can do.

  There is no restriction | limiting in particular in the inorganic flocculent used for this invention method, For example, a sulfuric acid band, polyaluminum chloride, ferric chloride, ferrous sulfate etc. can be mentioned. There is no restriction | limiting in particular in the addition amount of an inorganic flocculant, Although it can select suitably according to the property of the waste_water | drain to process, It is preferable that it is generally 500-5,000 mg / L as solid content. The organic coagulant used in the method of the present invention is not particularly limited, and examples thereof include polyethyleneimine, ethylenediamine-epichlorohydrin polymer, polyalkylene polyamine, diallyldimethylammonium chloride and quaternary ammonium salt of dimethylaminoethyl (meth) acrylate. And a cationic organic polymer such as a polymer. There is no restriction | limiting in particular in the addition amount of an organic coagulant, Although it can select suitably according to the property of the waste_water | drain to process, It is preferable that it is 1-100 mg / L in general as solid content.

  The organic polymer flocculant used in the method of the present invention is not particularly limited, and examples thereof include poly (meth) acrylic acid, a copolymer of (meth) acrylic acid and (meth) acrylamide, and an anionic polymer such as an alkali metal salt thereof. Molecular flocculants, nonionic polymer flocculants such as poly (meth) acrylamide, dimethylaminoethyl (meth) acrylate or quaternary ammonium salts thereof, dimethylaminopropyl (meth) acrylamide or quaternary ammonium salts thereof, etc. Examples thereof include cationic polymer flocculants such as homopolymers composed of cationic monomers, or copolymers of nonionic monomers copolymerizable with these cationic monomers. There is no restriction | limiting in particular in the addition amount of an organic polymer flocculant, Although it can select suitably according to the property of the waste water made into a process target, It is preferable that it is 1-20 mg / L in general as solid content.

In the wastewater treatment method of the present invention, other chemicals such as bactericides, deodorants, antifoaming agents, and anticorrosives can be used in combination as necessary. In the method of the present invention, other treatment methods such as ultraviolet irradiation treatment, ozone treatment, membrane treatment and biological treatment can be used in combination as necessary. The effect of the method of the present invention can be confirmed by measuring turbidity, COD _Mn , COD _{Cr and the} like for treated water.

  In the wastewater treatment method of the present invention, the wastewater treatment effect is improved by treating with a homogenizer before adding a liquid containing cationic or nonionic polymer fine particles to the wastewater, but this makes the particle diameter more uniform. The functional group comes to work efficiently, the surface of the polymer fine particle is subjected to shearing force, part of the polymer molecular chain is loosened and the functional group is easily exposed, and the surface is covered with a surfactant or paraffin. This is thought to be due to the activated surface of the fine polymer particles. By adding ionic polymer fine particles to the wastewater to be treated to adsorb the soluble COD component, suspended substances in the wastewater to be treated can be separated and removed simultaneously by the coagulation treatment. According to the method of the present invention, there is no blockage trouble that often occurs in the activated carbon tower for removing soluble COD, and wastewater treatment can be performed efficiently. For anionic soluble COD components, the ionic bonding action of the cationic functional group of the polymer fine particles, and for nonionic soluble COD components, hydrogen bonding by the nonionic functional group, hydrophobicity The binding action can effectively reduce turbidity and remove soluble COD components.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
Polymerization example 1
A four-necked separable flask equipped with a stirrer, a Dimroth condenser, a nitrogen inlet tube and a thermometer was charged with 165 g of kerosene mixed with 48 g of higher alcohol polyoxyethylene ether of HLB 9.5 and stirred vigorously in a nitrogen atmosphere. While stirring, a mixture of 190 g of a 65% by weight aqueous solution of methyl chloride quaternized with dimethylaminoethyl acrylate, 0.01 g of methylenebisacrylamide and 85 g of water was slowly added. The inside of the flask was kept at 50 ° C., and 0.65 g of a 10 wt% acetone solution of azobisisobutyronitrile was added as an initiator, and polymerization was carried out while stirring at 50 ° C. for 8 hours in a nitrogen atmosphere. . The reaction product was an insoluble polymer fine-particle gel that did not dissolve as a water-soluble polymer when placed in water.
The obtained polymer fine particles had an average particle size of 0.7 μm and a concentration of 30% by weight.

Example 1
The wastewater from the pulp and paper mill was treated. COD _Mn measured according to JIS K 0102 17. of this waste water was 480 mgO / L, and the scattered light turbidity measured using a formazine standard solution was 86 NTU according to JIS K 0101 9.3.
The liquid containing the cationic polymer fine particles obtained in Polymerization Example 1 was stirred for 30 seconds at a rotational speed of 5,000 rpm using a high-speed homogenizer [Microtec Nithion, Hiscotron (trade name), NS-60 type]. did.
Four 500 mL beakers containing 500 mL of waste water are attached to a jar tester, and after adding 400 mg / L of liquid sulfuric acid band [Al ₂ O ₃ 8% by weight] to each beaker and stirring at 150 rpm for 3 minutes, the above cationic polymer The stirring-treated liquid containing fine particles was added so that the concentration of the polymer fine particles was 2 mg / L and stirred for 3 minutes. Subsequently, 10% by weight aqueous sodium hydroxide solution was added dropwise to adjust the pH to be in the range of 6.8 to 7.2, followed by polymer flocculant [20 mol% hydrolyzed polyacrylamide, 1 mol / L. After adding 2 mg / L of intrinsic viscosity 21.5 dl / g measured at 30 ° C. using a sodium chloride aqueous solution as a solvent, the mixture was stirred at 150 rpm for 1 minute, and further stirred at 50 rpm for 3 minutes.
The particle size of the generated floc was visually observed, the turbidity of the supernatant was measured using a formazine standard solution according to JIS K 0101 9.3, and COD _Mn was measured according to JIS K 0102 17. The floc particle diameter was 7 mm, the turbidity was 14 NTU, and COD _Mn was 198 mgO / L.
The same operation was repeated with the addition amount of the cationic polymer fine particles added being 5 mg / L, 10 mg / L or 50 mg / L. When the polymer fine particle addition amount was 5 mg / L, the floc particle diameter was 7 mm, the turbidity was 12 NTU, and COD _Mn was 180 mgO / L. When the polymer fine particle addition amount was 10 mg / L, the floc particle diameter was 8 mm, the turbidity was 9 NTU, and COD _Mn was 165 mgO / L. When the polymer fine particle addition amount was 50 mg / L, the floc particle diameter was 8 mm, the turbidity was 8 NTU, and COD _Mn was 155 mgO / L.

Example 2
The same operation as in Example 1 was carried out except that the stirring conditions using the homogenizer of the liquid containing the cationic polymer fine particles obtained in Polymerization Example 1 were set at 5,000 rpm and the stirring time was 5 minutes.
When the polymer fine particle addition amount is 2 mg / L, the floc particle diameter is 7 mm, the turbidity is 16 NTU, and COD _Mn is 190 mg O / L. When the polymer fine particle addition amount is 5 mg / L, the flock particle diameter is 7 mm and the turbidity is 11 NTU. COD _Mn is 186 mgO / L, when the polymer fine particle addition amount is 10 mg / L, the floc particle diameter is 7 mm, the turbidity is 8 NTU, COD _Mn is 172 mgO / L, and when the polymer fine particle addition amount is 50 mg / L, The floc particle diameter was 8 mm, the turbidity was 7 NTU, and COD _Mn was 162 mgO / L.
Example 3
The same operation as in Example 1 was performed except that the stirring conditions using the homogenizer of the liquid containing the cationic polymer fine particles obtained in Polymerization Example 1 were set at 10,000 rpm and the stirring time was 5 minutes.
When the polymer fine particle addition amount is 2 mg / L, the floc particle diameter is 7 mm, the turbidity is 17 NTU, and COD _Mn is 189 mg O / L. When the polymer fine particle addition amount is 5 mg / L, the flock particle diameter is 7 mm and the turbidity is 9 NTU. COD _Mn is 186 mgO / L, when the polymer fine particle addition amount is 10 mg / L, the floc particle diameter is 7 mm, the turbidity is 9 NTU, COD _Mn is 170 mgO / L, and when the polymer fine particle addition amount is 50 mg / L, The floc particle diameter was 8 mm, the turbidity was 7 NTU, and COD _Mn was 159 mgO / L.
The results of Examples 1 to 3 are shown in Table 1.

Comparative Example 1
The same operation as in Example 1 was performed except that the liquid containing cationic polymer fine particles was not added to the waste water.
The floc particle diameter was 6 mm, the turbidity was 22 NTU, and COD _Mn was 210 mgO / L.
Comparative Example 2
The same operation as in Example 1 was performed except that the stirring conditions using the homogenizer of the liquid containing the cationic polymer fine particles obtained in Polymerization Example 1 were set to 5,000 rpm and the stirring time was 15 seconds.
When the polymer fine particle addition amount is 2 mg / L, the floc particle diameter is 6 mm, the turbidity is 18 NTU, and COD _Mn is 198 mg O / L. When the polymer fine particle addition amount is 5 mg / L, the flock particle diameter is 7 mm and the turbidity is 15 NTU. COD _Mn is 190 mg O / L, when the polymer fine particle addition amount is 10 mg / L, the floc particle diameter is 7 mm, the turbidity is 15 NTU, COD _Mn is 189 mg O / L, and when the polymer fine particle addition amount is 50 mg / L, The floc particle diameter was 8 mm, the turbidity was 14 NTU, and COD _Mn was 185 mgO / L.
Comparative Example 3
The same operation as in Example 1 was performed except that the stirring conditions using the homogenizer of the liquid containing the cationic polymer fine particles obtained in Polymerization Example 1 were set at 10,000 rpm and the stirring time was 15 seconds.
When the polymer fine particle addition amount is 2 mg / L, the floc particle diameter is 6 mm, the turbidity is 19 NTU, and COD _Mn is 195 mg O / L. When the polymer fine particle addition amount is 5 mg / L, the flock particle diameter is 7 mm and the turbidity is 16 NTU. , COD _Mn is 182 mgO / L, when the polymer fine particle addition amount is 10 mg / L, the floc particle diameter is 8 mm, the turbidity is 14 NTU, COD _Mn is 182 mgO / L, and when the polymer fine particle addition amount is 50 mg / L, The floc particle diameter was 8 mm, the turbidity was 14 NTU, and COD _Mn was 181 mgO / L.

Comparative Example 4
Instead of the stirring treatment liquid of the liquid containing the cationic polymer fine particles obtained in Polymerization Example 1, a homopolymer of methyl chloride quaternized product of dimethylaminoethyl acrylate, which is a normal cationic water-soluble polymer, was used. The same operation as in Example 1 was performed.
When the polymer addition amount is 2 mg / L, the floc particle diameter is 6 mm, the turbidity is 22 NTU, and COD _Mn is 210 mgO / L. When the polymer addition amount is 5 mg / L, the flock particle diameter is 6 mm, the turbidity is 20 NTU, COD _Mn is 210 mgO / L. When the amount of polymer added is 10 mg / L, the floc particle diameter is 7 mm, the turbidity is 19 NTU, COD _Mn is 200 mgO / L, and when the amount of polymer added is 50 mg / L, the floc particle diameter is 7 mm, turbidity was 18 NTU, and COD _Mn was 198 mgO / L.
Comparative Example 5
Instead of the stirring treatment liquid containing the cationic polymer fine particles obtained in Polymerization Example 1, powdered activated carbon [Kurita Industry Co., Ltd., Cricol (registered trademark) WD-514, density 0.35 kg / L] was used. The same operation as in Example 1 was performed except for the above.
When the amount of activated carbon added is 2 mg / L, the floc particle diameter is 6 mm, the turbidity is 21 NTU, and COD _Mn is 210 mgO / L. When the amount of activated carbon is 5 mg / L, the floc particle diameter is 6 mm, the turbidity is 21 NTU, COD _Mn is 206 mgO / L, when activated carbon addition amount is 10 mg / L, floc particle diameter is 7 mm, turbidity is 18 NTU, COD _Mn is 202 mgO / L, and when activated carbon addition amount is 50 mg / L, floc particle diameter is 7 mm, turbidity was 18 NTU, and COD _Mn was 199 mgO / L.
The results of Comparative Examples 1 to 5 are shown in Table 2.

As can be seen in Tables 1 and 2, a liquid containing water-insoluble cationic polymer fine particles as a waste water treatment agent is stirred for 30 seconds or 5 minutes at a rotational speed of 5,000 rpm or 10,000 rpm using a homogenizer. In Examples 1 to 3 using the obtained liquid, the turbidity and COD _{Mn of the} supernatant water are effectively reduced as compared with Comparative Example 1 in which the wastewater treatment agent other than the sulfuric acid band and the polymer flocculant is not used. . On the other hand, even if the liquid containing the same water-insoluble cationic polymer fine particles is stirred at a rotational speed of 5,000 rpm or 10,000 rpm using a homogenizer, the stirring time is 15 seconds. 3 and Comparative Example 4 using a normal cationic water-soluble polymer as a wastewater treatment agent and Comparative Example 5 using powdered activated carbon have little effect of lowering the turbidity and COD _Mn of the supernatant water. From this result, it is clear that the polymer fine particles were activated by the stirring treatment of the liquid containing the water-insoluble cationic polymer fine particles, and the wastewater treatment effect was improved.

  By the wastewater treatment method of the present invention, wastewater discharged from public wastewater sludge treatment facilities such as sewage treatment plants and human waste treatment plants, and discharged from chemical factories, printing factories, semiconductor factories, food factories, paper and pulp factories, etc. If the factory wastewater is treated, suspended substances and soluble COD components contained in the wastewater can be stably and efficiently removed. In addition, by applying the method of the present invention to wastewater treatment using inorganic flocculants, the amount of inorganic flocculants used is reduced, the amount of sludge that is industrial waste is reduced, and disposal costs are reduced and the global environment is protected. It can contribute greatly.

Claims (3)

  In a wastewater treatment method in which cationic or nonionic polymer fine particles that swell in water and do not substantially dissolve in water are added to wastewater, and after agglomeration reaction, the liquid containing the polymer fine particles is treated with a homogenizer. A wastewater treatment method characterized by being added to wastewater after being performed for at least 2 seconds.   The wastewater treatment method according to claim 1, wherein the polymer fine particles which swell in water and do not substantially dissolve in water are cationic polymer fine particles.   The wastewater treatment method according to claim 2, wherein the cationic polymer fine particles are a polymer composed of one or more monomers including a quaternary ammonium salt monomer using a bifunctional monomer as a crosslinking agent.